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LEACHING OF LEAD FROM ELECTRONICS WASTE
USING SIMULATED MUNICIPAL SOLID WASTE LANDFILLS
By
ERIK E. K. SPALVINS
A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
2006
Copyright 2006
by
Erik E. K. Spalvins
To children with lead poisoning.
iv
ACKNOWLEDGMENTS
This study was made possible by the cooperation and support of many people.
Many thanks go to the Florida Center for Solid and Hazardous Waste Management, the
Polk County Solid Waste Division, and the Polk County Board of County Commissioners
for funding this work. I would especially like to thank John Schert, Ana Wood, and
Brooks Stayer for their support. I also thank to all the people at the Polk County Solid
Waste Division. They provided cheerful assistance and great solutions to many
problems.
I thank my supervisory committee chair (Dr. Timothy Townsend) for providing this
and many other opportunities to be involved with fascinating projects and to work with
wonderful people. I offer sincere thanks to my committee members (Dr. Michael
Annable and Dr. Jean-Claude Bonzongo) for their support.
Other organizations and people who provided support include Bernadette
Thavarajah from Publix Supermarkets, local managers at the Auburndale Publix and
Thornhill Publix, Recycle America, Gainesville Waste Management, Alachua County
Solid Waste Division, Sumter County Solid Waste Division, Jim Chapin from Applied
Recycling Technologies, Allan Roe from Roe Enterprises, Packer Industries, Bill Boone,
Greta Hilde, and the University of Florida Physical Plant.
The interest, enthusiasm, and sweat of fellow graduate students was invaluable. I
would especially like to thank Dr. Brajesh Dubey, Tobin McKnight, Matt Farfour, Sylvie
Martin, Judd Larsen, Dr. Jenna Jambeck, Jae Hac Ko, Dr. Qiyong Xu, Dr. Hwidong Kim,
v
Kim Cochran, Aaron Jordan, Murat Semiz, Dr. Pradeep Jain, Sreeram Jonalagaada, and
last, but not least, Dr. Thabet Tolaymat. Many other students also greatly contributed to
this project, but they are too numerous to list.
My personal thanks go to my advisor for the friendship, fun, and personal growth I
experience during the last 3 years. This project would not have happened without the
love and support of my parents and family. Finally, thanks go to my friends who
provided companionship along the way.
vi
TABLE OF CONTENTS
page
ACKNOWLEDGMENTS ................................................................................................. iv
LIST OF TABLES........................................................................................................... viii
LIST OF FIGURES .............................................................................................................x
ABSTRACT...................................................................................................................... xii
CHAPTER
1 INTRODUCTION .........................................................................................................1
1.1 Problem Statement..................................................................................................1 1.2 Objectives ...............................................................................................................2 1.3 Research Approach.................................................................................................3
2 LITERATURE REVIEW ..............................................................................................4
2.1 Electronics Waste ...................................................................................................4 2.2 Regulatory Issues....................................................................................................5 2.3 Hazardous Waste Characterization of E-waste.......................................................8 2.4 Simulated Landfill Studies ...................................................................................10 2.5 Waste Decomposition in Landfills .......................................................................11 2.6 Leaching Behavior................................................................................................14
3 MATERIALS AND METHODS ................................................................................17
3.1 Lysimeter Construction and Installation...............................................................17 3.1.1 Lysimeter Construction ..............................................................................17 3.1.2 Lysimeter Installation.................................................................................18
3.2 Waste Preparation and Lysimeter Loading...........................................................19 3.2.1 Excavated Waste Preparation .....................................................................19 3.2.2 Synthetic Waste Preparation.......................................................................19 3.2.3 Waste Mixing .............................................................................................23 3.2.4 Electronics Waste Preparation....................................................................23 3.2.5 Lysimeter Loading......................................................................................24 3.2.6 Placement of E-waste .................................................................................25 3.2.7 Water Distribution System .........................................................................26
vii
3.3 Lysimeter Operation .............................................................................................27 3.3.1 Water Addition ...........................................................................................27 3.3.2 Leachate Collection ....................................................................................28 3.3.3 Gas Sampling..............................................................................................30 3.3.4 Settlement Measurement ............................................................................30 3.3.5 Temperature Measurement .........................................................................30
3.4 Laboratory Methods..............................................................................................31 3.4.1 Leachate Analysis.......................................................................................31 3.4.2 Solid Digestion of Synthetic Wastes ..........................................................33 3.4.3 Data Analysis..............................................................................................33
4 RESULTS....................................................................................................................34
4.1 Lysimeter Leachate Data ......................................................................................34 4.1.1 Lysimeter Leachate Data Compared to Typical Landfill Conditions ........34 4.1.2 Lysimeter Lead Concentrations..................................................................43 4.1.3 Statistical Analysis .....................................................................................50
4.2 Sources of Lead in Lysimeters .............................................................................52
5 DISCUSSION..............................................................................................................56
6 SUMMARY AND CONCLUSIONS..........................................................................65
APPENDIX
A PROJECT PHOTOGRAPHS ......................................................................................68
B ADDITIONAL LEACHATE GRAPHS......................................................................78
C ADDITIONAL DATA ................................................................................................82
LIST OF REFERENCES.................................................................................................103
BIOGRAPHICAL SKETCH ...........................................................................................108
viii
LIST OF TABLES
Table page 3-1 Lysimeter name, contents, mass of synthetic waste, E-waste and water on field
weight basis, and lysimeter density..........................................................................20
3-2 Materials used for simulated waste ..........................................................................22
3-3 Type and source of electronics waste used in this study..........................................24
3-4 Leachate analysis and methods ................................................................................32
4-1 Lysimeter leachate pH and COD compared to literature values ..............................37
4-2 Lysimeter leachate lead parameters .........................................................................47
4.3 Statistical analysis ....................................................................................................51
4-4 Sources of lead in synthetic waste ..........................................................................53
4-5 Estimated mass of lead in E-waste lysimeters .........................................................55
C-1 Detailed composition of E-waste components .........................................................82
C-2 Leachate lead concentrations ...................................................................................83
C-3 Leachate lead descriptive statistics ..........................................................................83
C-4 Leachate pH..............................................................................................................84
C-5 Leachate total volatile fatty acids.............................................................................86
C-6 Leachate biochemical oxygen demand ....................................................................86
C-7 Leachate chemical oxygen demand..........................................................................87
C-8 Leachate total organic carbon ..................................................................................88
C-9 Leachate oxidation reduction potential ....................................................................89
C-10 Leachate conductivity ..............................................................................................90
ix
C-11 Leachate total dissolved solids.................................................................................91
C-12 Leachate alkalinity ...................................................................................................92
C-13 Leachate chloride .....................................................................................................93
C-13 Leachate sulfides ......................................................................................................93
C-14 Volume of leachate collected ...................................................................................94
C-15 Volume of water added ............................................................................................96
C-16 Water balance...........................................................................................................98
C-17 Methane gas composition in lysimeter...................................................................100
C-18 T-test comparing control 1 and control 2 ...............................................................101
C-19 Single factor analysis of variance for E-waste lysimeters......................................101
C-20 Two-factor analysis of variation for control 1, control 2, E-waste 1, and E-waste 2 ................................................................................................................102
x
LIST OF FIGURES
Figure page 2-1 Typical landfill gas and leachate composition in MSW landfills ............................13
3-1 Construction detail of top and bottom of lysimeter..................................................18
3-2 Waste composition from literature used to create synthetic waste ..........................21
3-3 Placement of E-waste in Lysimeters ........................................................................27
3-4 Cumulative volume of water added to lysimeters. ...................................................29
4-1 Leachate pH versus time ..........................................................................................40
4-2 Lysimeter leachate NPOC versus time.....................................................................41
4-3 Leachate COD (linear scale) versus time .................................................................41
4-4 Leachate COD (log-scale) versus time.....................................................................42
4-5 Lysimeter leachate Eh versus time...........................................................................42
4-6 Lysimeter methane concentrations versus time........................................................43
4-7 Leachate lead concentration vs.time. .......................................................................48
4-8 Leachate lead concentration vs.liquid to solid ratio. ................................................49
4-9 Box plot of leachate lead concentrations by lysimeter.............................................49
4-10 Cumulative lead leached vs. liquid to solid ratio. ....................................................50
5-1 Lead concentrations from historic landfill leachate and lysimeter studies compared to the current study ..................................................................................60
A-1 Lysimeter during construction .................................................................................68
A-2 Detail of welding triplanar geonet............................................................................69
A-3 Outside view of geonet covering hole......................................................................69
xi
A-4 Elbow used to connect lysimeter to leachate collection pipe...................................70
A-5 Bucket auger.............................................................................................................70
A-6 Lowering lysimeter into landfill...............................................................................71
A-7 Backfilling around lysimeter with sand ...................................................................71
A-8 Water distribution system irrigation tubing .............................................................72
A-9 Adding water to lysimeter ........................................................................................72
A-10 Material used for simulated waste............................................................................73
A-11 Mixing simulated waste ...........................................................................................73
A-12 Adding water to simulated waste .............................................................................74
A-13 Disassembled CRT monitor .....................................................................................74
A-14 Central processing unit in lysimeter.........................................................................75
A-15 Monitor in lysimeter.................................................................................................75
A-16 Smoke detectors in lysimeter ...................................................................................76
A-17 Cell phones and rechargeable batteries in lysimeter ................................................76
A-18 Waste compactor ......................................................................................................77
A-19 Silicone caulk used to seal lysimeter........................................................................77
B-1 Lysimeter water balance...........................................................................................78
B-2 Liquid to solid ratio ..................................................................................................78
B-3 Total volatile fatty acids vs. time .............................................................................79
B-4 Biochemical oxygen demand vs. time......................................................................79
B-4 Conductivity vs. time ...............................................................................................80
B-5 Total dissolved solids vs. time .................................................................................80
B-6 Alkalinity vs. time ....................................................................................................81
B-7 Settlement vs. time ...................................................................................................81
xii
Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science
LEACHING OF LEAD FROM ELECTRONICS WASTE USING SIMULATED MUNICIPAL SOLID WASTE LANDFILLS
By
Erik E. K. Spalvins
May 2006
Chair: Timothy G. Townsend Major Department: Environmental Engineering Sciences
Electronics waste (E-waste) consists of discarded electronic equipment, generally
considered any device containing a circuit board. Some types of E-waste are considered
hazardous waste in the United States. In many places, landfill disposal of E-waste is
restricted because of concerns that toxic compounds, especially lead, could leach from
the waste and result in risk to human health and the environment. This study uses
simulated landfills or lysimeters to examine how lead leaches as a result of adding
E-waste to lysimeters filled with simulated municipal solid waste (MSW). Two
lysimeters were built with only simulated waste (control lysimeters), three with simulated
waste plus about 6% E-waste (E-waste lysimeters), and one filled with waste excavated
from a landfill (excavated waste). The lysimeters were placed in holes excavated in an
operating MSW landfill in Florida. Water was added regularly and leachate was
collected for approximately 1 year.
xiii
Leachate from the control and E-waste lysimeters was typical of acid-phase
leachate throughout the study. The excavated waste lysimeter was in the acid phase
briefly and was fully methanogenic after 150 days. The highest concentrations of lead
occurred in the excavated waste lysimeter during the acid phase and decreased to below
detection limit in the methanogenic phase. Concentrations of lead from the control and
E-waste lysimeters were statistically different at the α = 0.05 level of significance. The
total mass of lead leached from the E-waste lysimeters was on average 22% greater than
from the control lysimeters. However, the increase in the mass of lead leached from the
E-waste lysimeters was less than 0.018% of the total lead that was added as part of the
E-waste.
A major implication of this study is that the regulatory scheme for managing
E-waste may be overprotective for lead leaching from E-waste. As a result, policymakers
may be misallocating limited public health and environmental-protection resources.
Ultimately, better risk assessments will lead to more effective and efficient spending of
resources to reduce the potential for lead exposure. Future research should focus on the
remaining uncertainties in groundwater modeling and understanding the chemistry and
long-term consequences of E-waste disposal in landfills.
1
CHAPTER 1 INTRODUCTION
1.1 Problem Statement
Electronics waste (E-waste) refers to discarded electronic equipment, including cell
phones, batteries, computers, monitors, and televisions. In general, E-waste is any item
that contains a circuit board. Recently, the disposal of E-waste has become a significant
concern because it can contain materials that are toxic to humans and the environment.
For instance, lead is used as solder on circuit boards and as radiation-shielding in cathode
ray tubes (CRTs) in TVs and monitors.
The main health concern with disposing of E-waste in landfills is that toxic heavy
metals, especially lead, could dissolve or leach into the liquid passing through the landfill
and contaminate groundwater. Health concerns are not the only motivation for limiting
E-waste disposal. Facility operators are also concerned that elevated metal
concentrations in leachate could increase leachate treatment costs in the near term and
prolong post-closure care in the long-term. Another concern is the potential impact on
landfill reuse options involving landfill mining. Because of these concerns, some states
and many local communities have banned E-waste disposal at municipal solid waste
(MSW) landfills (Commission of European Communities (CEC), 2000; Global Futures
Foundation (GFF), 2001).
However, the potential for lead exposure from E-waste disposal in landfills is a
subject of much debate. Some maintain that landfills accepting E-waste will undoubtedly
cause groundwater contamination (Scanlon, 2001). Others argue that landfills are
2
capable of safely isolating the heavy metals in E-waste from human contact (SWANA,
2004). Unfortunately, the true environmental impact of different disposal and recycling
options is uncertain.
The challenge for regulators on the federal and state level is to decide in the face of
this uncertainty what regulatory remedy is appropriate for E-waste. Current national
hazardous waste regulations require special management of E-waste due to the leaching
of lead. However, the effectiveness of the regulatory test to simulate real-world
conditions has been questioned. Also, regulatory limits in the United States may not
deliver the originally intended level of protectiveness. To address these issues, this study
uses simulated landfills to examine the leaching of lead from E-waste under MSW
landfill conditions. The results are compared to regulatory tests and historical data from
landfill and simulated landfill studies. This information can be used by policymakers
when developing risk and exposure-based priorities to protect human health and the
environment from lead exposure from the disposal of E-waste.
1.2 Objectives
The objective of this study is to assess the leaching behavior of lead from E-waste.
Currently, the ability to predict the leaching behavior of wastes in landfills is limited.
Simulated landfills (lysimeters) were used to leach E-waste under the conditions that
occur in actual landfills. The lysimeter results are compared to historic landfill and
lysimeter studies to understand the broader environmental and policy implications.
Specific objectives of this study:
• Compare the mass of lead leached from lysimeters that contain no E-waste to lysimeters containing a relatively high content of E-waste.
• Compare results to lead data from historic lysimeter studies and historic landfill data, as well as to regulatory levels.
3
• Discuss regulatory approach and regulatory levels.
• Discuss impact of study on the development of future regulations.
1.3 Research Approach
In this study, the leaching behavior of lead was simulated using lysimeters filled
with different waste mixtures. Because temperature control was a problem in previous
studies (Pohland, 1975; Jambeck, 2004), the lysimeters were buried inside an MSW
landfill. Two control lysimeters contained only a simulated waste mixture. Three
experimental lysimeters contained the simulated waste and about 25 kilograms
(56 pounds) of E-waste (~6% of the field weight of the synthetic waste). One lysimeter
was filled with waste excavated from the landfill in which the lysimeters were buried. A
digital answering machine was noticed in the excavated waste, but the mass was not
quantified. Water was added to the lysimeters regularly. The lysimeters were compared
in terms of water quality and lead concentrations. The total mass of lead leached from
each lysimeter was calculated from the lead concentrations and the volume of leachate
collected. Potential sources of lead in the lysimeter were determined by analyzing the
synthetic waste components.
This thesis is organized into five chapters. Chapter 2 is a literature review giving a
brief description of E-waste, hazardous waste regulations, leaching behavior, and
leaching tests. Chapter 3 presents the methods and materials. Chapter 4 contains the
results. Chapter 5 discusses the results and presents implications of this work and
potential future research questions. A summary is presented in Chapter 6. Appendices
are attached containing additional data and documentation.
4
CHAPTER 2 LITERATURE REVIEW
2.1 Electronics Waste
E-waste is a priority for solid waste policymakers because it is a significant and
increasing portion of the waste stream, and it contains toxic chemicals (CEC, 2000).
Estimates for the amount of E-waste in the waste stream are as high as 5% by weight
(GFF, 2001). But recent waste composition studies in the United States found that
E-waste comprises approximately 1.5% of the waste discarded (R.W. Beck Inc.; 2000,
Franklin Associates, 2003). E-waste as a percent of total discards in the United States
increased from 1.2% in 2000 to 1.5% in 2003 (Franklin Associates, 2003). In Europe, the
quantity of E-waste is predicted to increase from 3 to 5% annually (CEC, 2000). Toxic
chemicals in E-waste can include lead, cadmium, chromium, mercury, and also organic
compounds, such as brominated flame retardants. Lead is the chemical of most concern
due to its toxicity and widespread use in E-waste.
The amount of lead in E-waste varies. The main use of lead in E-waste is in
cathode ray tube (CRT) glass and solder. Cathode ray tubes contain approximately 1.6 to
3.2 kilograms of lead (Jang & Townsend, 2003). One report says the average computer
with a monitor contains 6.3% lead by weight, with most of the lead being from the CRT
(Pedersen et al., 1996). A recent California study showed that the total lead content from
a variety of E-wastes ranged from 0.5% for cell phones and central processing units
(CPUs) to 0.005% for microwave ovens (CDTSC, 2004a; CDTSC, 2004b).
5
Absent regulatory intervention, the ultimate fate of “discarded” E-waste would be
burial in a municipal solid waste (MSW) landfill or in an MSW waste-to-energy ash
landfill. Regulations in the United States assume that the main exposure pathway for
contaminants placed in landfills is through the consumption of contaminated groundwater
(45 FR 33110). But how dangerous is E-waste in landfills? What is the potential risk to
human health from burying E-waste in landfills? These are the central questions for
policymakers who must decide how to manage E-waste while protecting people and the
environment. However, the environmental impact of disposing E-waste in landfills is a
subject of debate. Better information will enable policies to provide the intended level of
protection without wasting limited public health or environmental protection resources.
As a result of these concerns, new regulations have been and continue to be
developed to reduce the amount of toxic chemicals used in E-waste, encourage the
recycling of E-waste, and restrict the disposal of E-waste in landfills and incinerators.
Many regulators and landfill operators have applied the precautionary principle and
restricted E-waste disposal. For instance, a number of states, such as Massachusetts in
2000, California in 2002, and Maine at the beginning of 2006, have banned CRTs from
landfill disposal. Minnesota will ban CRTs from landfills as of July 1, 2006 (MOEA,
2005). California has gone further. Universal waste (including all electronics, mercury
lamps, all batteries, and greeting cards that play music) may not be disposed of in
landfills (CDTSC, 2006). On a local level, individual landfill operators have chosen to
either ban E-waste or have established programs to divert E-waste from landfill disposal.
2.2 Regulatory Issues
In the United States, the Resource Conservation and Recovery Act (RCRA)
regulates solid and hazardous waste and assigns the EPA the responsibility of setting
6
specific regulations. Subtitle D of RCRA deals with solid waste and regulates MSW,
non-hazardous industrial waste, and special wastes. Subtitle C of RCRA defines
hazardous wastes as a subset of solid waste, and it regulates the production, handling, and
disposal of hazardous wastes (EPA, 2003). The EPA has established two different ways
of identifying hazardous wastes: listing specific wastes as hazardous and identifying the
characteristics that would make a waste hazardous. Listed hazardous wastes are
identified specifically by law, whereas characteristic hazardous wastes are classified as
having one of four characteristics: toxicity, ignitability, reactivity, or corrosivity.
The EPA first established standardized test methods for each characteristic in 1980
(45 FR 33084). Test results were compared to regulatory levels designed to “provide a
high degree of certainty that wastes exceeding those regulatory levels would pose hazards
to human health and the environment if improperly managed” (61 FR 11799). The 1980
regulations established the characteristic of Extraction Procedure (EP) toxicity to identify
wastes that are hazardous based on the potential for toxic compounds to leach into
groundwater “under the conditions of improper management” (45 FR 33110). The EP
was a batch leaching test intended to “simulate the leaching action that occurs in
landfills” by subjecting a sample of waste to an acidic solution for 24 hours under
constant agitation (45 FR 33127). The 14 contaminants for which wastes could be
considered an EP toxicity characteristic waste included: arsenic, barium, cadmium,
chromium, lead, mercury, selenium, silver, four insecticides, and two herbicides. The EP
regulatory levels were based on the National Interim Primary Drinking Water Standards,
multiplied by a dilution and attenuation factor (DAF) of 100. The EPA originally
7
proposed a DAF of 10, but instead chose 100 because the groundwater models available
in 1980 were not adequate to justify the more restrictive DAF of 10 (45 FR 33111).
The Hazardous and Solid Waste Amendments of 1984 directed the EPA to revise
the EP toxicity characteristic and add more toxicants to the list of toxicity. As a result,
the characteristic of EP toxicity was replaced with the Toxicity Characteristic (TC) in
1990. Toxicity characteristic wastes are identified using a procedure called the Toxicity
Characteristic Leaching Procedure (TCLP), which replaced the EP. The TCLP was
developed to use a more aggressive leaching solution, better simulate the leaching of
organic compounds, and refine technical aspects of the EP (55 FR 11801).
The TCLP is described in SW 846 method 1311. One hundred grams of the waste
is size-reduced and placed in an acetic acid leaching solution for 18 hours and agitated.
The resulting leachate is filtered and analyzed for the TC compounds, and the
concentration of each is compared to the TC limit. If the concentration of a contaminant
in the TCLP leachate exceeds the TC limit, the waste becomes a toxicity characteristic
hazardous waste.
In the 1990, toxicity characteristic (TC) limits were established for 25 new organic
compounds, and the EP limits for the 14 existing compounds were retained. As with the
EP limits, the TC limits are intended to prevent groundwater near a landfill from being
contaminated above risk-based toxicity levels. The EPA back-calculated TC limits for
the 25 new compounds by multiplying risk-based exposure limits by dilution and
attenuation factors (DAF). The DAFs for the organic compounds were determined using
a groundwater transport model, the EPA’s Composite Model for Landfills (EPACML)
(55 FR 11816). The DAFs calculated by the EPACML were all within an order of
8
magnitude of 100. For simplicity, the EPA applied a DAF of 100 for the organic TC
compounds.
The TC limit for lead, 5.0 mg Pb/L, was calculated in 1980 by multiplying the
existing drinking water standard of 50 µg/L by a generic DAF of 100. Because the
EPACML could not model inorganic compounds, the EPA chose to retain the existing EP
limits for the inorganic compounds. In both the 1980 and 1990 rulemakings, the EPA
stated that the DAFs for inorganic compounds could be revised if improvements in
groundwater models in the future allowed for the accurate determination of new DAFs
(45 FR 33111, 55 FR 11813).
2.3 Hazardous Waste Characterization of E-waste
The fundamental assumption of waste characterization is that the potential for
contaminants to be released into the environment can be predicted from an understanding
of the chemical and physical processes surrounding the waste. One of the criticisms of
the Toxicity Characteristic is that the TCLP and the accompanying TC limit do not
realistically simulate the leaching and transport of metals.
Many E-wastes have been subjected to the TCLP and exceeded the TC limit for
lead, potentially classifying those E-wastes as a hazardous waste. Musson et al. (2000)
conducted the TCLP on CRT glass and found that the weighted average TCLP lead
concentration was 18.5 mg Pb/L, compared to the TC limit of 5.0 mg Pb/L. Ching and
His (2002) also found TCLP concentrations from CRT glass to be above the TC limit for
lead. While such studies are useful to identify potential wastes of concern, the TC status
of an electronic device is not determined by the leaching results of the individual
components.
9
Because of the difficulty of size-reducing a computer or monitor, a large scale
TCLP was developed (Vann, 2003; Vann et al., 2005). In the large-scale TCLP, an entire
electronic device could be leached in a rotating drum, avoiding the difficulty of size-
reduction and obtaining a homogenous sample from E-waste. The volume of extraction
fluid was adjusted to maintain the same amount of liquid to waste ratio as the TCLP. The
normal TCLP was also conducted by size-reducing all components of a computer central
processing unit (CPU) and mixing them to make a composite CPU mixture. The lead
concentration was higher in the large-scale TCLP than the normal TCLP (Vann et al.,
2005). It was also noted that the normal TCLP was more reducing than the large scale
TCLP. Since lead is more soluble under oxidizing conditions, Vann et al. (2005)
concluded that the redox chemistry was responsible for the difference in lead leaching.
The size reduction in the normal TCLP increased the availability of iron and zinc to
change the redox conditions (Vann et al., 2005).
An in-depth study of the potential of E-waste to meet the definition of a TC waste
was completed by Townsend et al. (2004) entitled, “RCRA Toxicity Characterization of
Computer CPUs and Other Discarded Electronic Devices.” The study examined the
leaching of 12 types of E-waste using the TCLP, a modified large-scale TCLP (as
described in Vann et al., 2005), and a modified small-scale TCLP in which 100 g of
E-waste was disassembled but not size-reduced. In total, 228 E-wastes were tested using
the TCLP or a modified TCLP, and 156 of them exceeded the TC limit for lead
(Townsend et al., 2004).
The classification of E-waste as a TC hazardous waste has raised many questions
about the appropriateness of the TC regulations. Concerns have been raised about the
10
ability of the TCLP to simulate leaching under landfill conditions (Van der Sloot, 1996).
Some of the concerns are centered on the type of leaching fluid used for the TCLP.
Batch leaching tests conducted using actual landfill leachate extracted approximately two
orders of magnitude less lead from E-waste than the TCLP (Jang & Townsend, 2003).
The decreased leaching of lead was attributed to the lower pH and higher concentration
of organic acid in the TCLP leaching fluid than in the landfill leachates used. Another
concern is that the TCLP does not consider the role of biological activity in the landfill.
Despite these uncertainties, the TCLP concentration it is often assumed to represent the
concentration at the bottom of the landfill. A number of risk and life-cycle assessments
have used TCLP results for E-waste to calculate environmental impacts without much
comment (Socolof, et al., 2001).
2.4 Simulated Landfill Studies
Techniques other than batch leaching studies are available for the prediction of
leaching behavior. One of the most widely used techniques is building a simulated
landfill, or lysimeter, containing the material of interest, then infiltrating liquid and
analyzing the resulting leachate. Lysimeters can vary in scale from benchtop studies 10
milliliters in volume to field-scale studies several hectares in area and several meters
deep. While lysimeter tests might be inappropriate as regulatory tests because of the
difficulty and length of the experiments, they are useful for understanding the processes
occurring in landfills and for verification of contaminant transport models and leaching
tests.
The history of simulated landfills for studying MSW landfills is full of diverse
experiments. Pohland (1975) explored the use of leachate recirculation to speed up MSW
decomposition with four 1 meter diameter, 4.5 meter tall simulated landfills. Kemper et
11
al. (1984) constructed 2.1 meter wide, 3.4 meter long, and 3.7 meter deep simulated
landfills to compare the effect of shredding and/or baling waste before landfilling on
leachate production and quality. Ehrig (1988) discussed temperature-controlled 120 liter
lab-scale lysimeter tests and buried 5 meter diameter, 6 meter high lysimeters for
determining water and element balances of landfills. More recently, lysimeter studies
have been used to evaluate the impact of specific wastes on landfill leachate quality.
Jambeck (2004) evaluated the effect of disposing of chromated copper arsenate pressure-
treated wood in lysimeters simulating wood monofills, construction and demolition
landfills, and MSW landfills.
Lysimeter tests are not without shortcomings. They are generally not appropriate
as regulatory tests for screening wastes because the amount of time required for
completing the test. One problem encountered by Pohland (1975) and Jambeck (2004)
was temperature control. Both studies placed the lysimeters outside, and as a result, the
temperatures inside the lysimeters were largely dictated by ambient temperatures.
Landfills are typically large enough to self-insulate, allowing internal temperatures to be
elevated by the metabolism of microorganisms. Other difficulties with lysimeter studies
include preparing wastes, reaching waste densities typical of landfills, and simulating the
hydraulic properties of landfills.
2.5 Waste Decomposition in Landfills
One advantage lysimeter studies have over batch leaching tests is the ability to
integrate the biological and chemical interactions, which occur in the landfill, into the
leaching study (Van der Sloot & Dijkstra, 2004). The decomposition of MSW in landfills
has been described widely in the literature as occurring in a number of phases (Pohland &
Kim, 1999; Tchobanoglous et al., 1993; Tolaymat et al. 2004; Youcai et al., 2002;
12
Christensen et al., 2001). The first phase is initial adjustment, in which aerobic
decomposition occurs until the supply of oxygen is consumed. The second phase is
called the transition phase. Oxygen is depleted and nitrate and sulfate are used as final
electron acceptors and are reduced. The pH begins to decrease as the amount of organic
acids and carbon dioxide increases.
The third phase, the acid phase, is characterized by conversion of organic matter to
organic acids, the production of CO2 and H2 gas, and the decrease of pH to 5 or lower.
Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) in the leachate
increase due to the dissolved organic matter and organic acids present. The leaching of
heavy metals is expected to be greatest in the acid phase due to the low pH and the
increased amount of dissolved organic matter.
During the fourth phase, methane fermentation, or the methanogenic phase, organic
acids, H2 gas, and other compounds are converted into CH4 and CO2 by strict anaerobic
microorganisms called methanogens. This process, called methanogenesis, often occurs
in close relationship with other types of microorganisms. The consumption of organic
acids decreases COD and BOD, and causes the pH to increase to a neutral range, from
6.8 to 8. Conditions in the waste become more reducing as methanogenesis occurs at
highly reducing conditions. The methane composition of the gas increases. The fifth
phase is maturation which begins once the decomposition is nearly complete. The
consumption of oxygen decreases in the waste, and oxygen may begin to infiltrate the
waste.
Typical gas and leachate composition during the different stages of decomposition
are shown in Figure 2-1. The time scale in Figure 2-1 represents leachate recirculation in
13
a lysimeter study. Actual lengths of phases vary. For instance, Pohland and Kim, (1999)
discuss lysimeters which were in the acid phase for 800 days before leachate
neutralization and reseeding of microorganisms helped transition the lysimeters into
methanogenic conditions. The exact distinction between phases is difficult, especially in
landfills because they are large and heterogeneous systems. Further complicating clear
distinctions between phases is the sequential placement of wastes in landfills. In
lysimeter studies, this distinction may be easier to see, but it becomes less clear as the
lysimeter gets larger.
Figure 2-1. Typical landfill gas and leachate composition in MSW landfills (Pohland, F.
and Kim, J., 1999, “In situ Anaerobic Treatment of Landfills for Optimum Stabilization and Biogas Production.” Water Science and Technology, 40(8), pp 203-210, Figure 1, page 204)
The reported pH ranges for the acid and methanogenic phases vary somewhat, but
generally waste is considered to be in the acidic phase when the pH ranges from 4.5 to
6.5 and in the methanogenic phase from 6.5 to 8.5. This range is based on the optimum
pH range for methanogenic bacteria. Ehrig (1988) identified the average acidic pH as
6.1, ranging from 4.5 to 7.5 and the average methanogenic pH as 8, ranging from 7.5 to 9.
14
Chemical oxygen demand ranges for the acidic phase have been reported from 6,000 to
60,000 mg/L, averaging 22,000 mg/L, and from 500 to 4,500 mg/L for the methanogenic
phase, averaging 13,000 mg/L (Ehrig, 1988). In a recent study of 41 landfill leachates in
Florida (Townsend et al., 2003), only three landfills were found with a pH less than 6.5.
2.6 Leaching Behavior
The leaching of lead from landfills requires the solubilization into the liquid phase
and migration through the waste. A systematic approach to leaching processes is
presented in Van der Sloot (1996) and Van der Sloot and Dijkstra (2004). While their
work specifically addresses inert wastes, the processes apply to MSW landfills. Once
lead becomes mobile, it must be able to migrate through the landfill to get out and cause
environmental harm. Finally, the migration of heavy metals from landfills and through
groundwater is discussed.
Van der Sloot (1996) described the release of contaminants from waste in terms of
the chemical and physical factors contributing to leaching behavior. The chemical
factors of the leaching environment include pH, redox conditions, organic matter, ionic
strength, and chemical composition of the water. Important chemical characteristics of
the waste include the chemical form of the contaminant and the total mass of contaminant
present. Temperature and time can also be a factor. Finally, biological activity is very
important for leaching behavior in MSW landfills because it controls important
parameters, such as pH, redox conditions, dissolved organic matter, and generation of
CO2.
The pH of the system is crucial as the solubility of many compounds, especially
metals, is pH-dependant, as are sorption processes. As discussed earlier, pH changes in
landfills as waste decomposes. The acidic phase of a MSW landfill leachate may be as
15
brief as one year so the majority of leaching will occur under neutral pH conditions.
Oxidation and reduction conditions can influence speciation and solubility for some
contaminants. Dissolved organic matter forms complexes with metals, increasing
solubility. Metal speciation studies have shown that substantial fractions of “dissolved”
(passing a 0.45 µm pore-size filter) heavy metals in leachate-contaminated groundwater
are actually bound to colloidal solids (Christensen et al., 2001). As ionic strength
increases, the leachability of contaminants generally increases. Also, chemicals in the
water, such as chloride ions, can form complexes with some contaminants. Finally, time
can be a factor for reactions involving mineral transformations or biological activity
dependant on nutrient availability or microbial growth rates.
The chemical form of a contaminant (i.e., mineral or organic, oxidized or reduced)
can influence the leaching behavior as well. Van der Sloot & Dijkstra (2004) pointed out
that heavy metals complexed with humic substances, such as in wood, can be much more
soluble than non-complexed forms. The total mass of contaminant in a waste influences
leaching concentrations for highly soluble compounds, but may not have much influence
if the leaching is dominated by the leachate chemistry.
The physical factors influencing the release of contaminants as described by Van
der Sloot & Dijkstra (2004), mostly relate to monolithic or granular wastes, but some are
relevant. Particle size is important for wastes in MSW landfills as smaller particles
expose more surface area to decomposition and leaching. Hydraulic conductivity and
porosity of MSW is important for the transport of leachate, dispersion of moisture,
contact time, and mobility of nutrients for microorganisms. Channeling or short-
circuiting of leachate can reduce the contact time of the leachate with the waste.
16
Once mobilized into leachate, metals can be attenuated within the landfill. The
processes should be similar to those occurring in leachate plumes. In landfill leachate
plumes, sorption, precipitation, and dilution play the largest roles in the attenuation of
lead, with complexation acting to increase solubility and mobility (Christensen et al.,
2001).
17
CHAPTER 3 MATERIALS AND METHODS
This study consists of the construction, installation, and operation of a lysimeter
study, the analysis of the resulting leachate, and the analysis of the waste used to fill the
lysimeters. The lysimeters were filled with a simulated waste mixture and E-waste. In
order to accommodate the E-waste without drastic size reduction, the lysimeters were
designed with a 0.57 meter (22 inch) inside diameter. This dimension allowed for
thorough contact between the E-waste and the leachate. The next consideration was the
material to be used for the lysimeters. High Density Polyethylene (HDPE) pipes were
chosen because of the inert nature of HDPE compared to metal or polyvinyl chloride
pipe, the durability and resistance to breakage, and the widespread use of HDPE in
landfill liner systems and leachate collection systems. To maintain the appropriate
temperature for anaerobic microorganisms, the lysimeters were buried in an MSW
landfill. Photographs of the lysimeter construction and installation are included in
Appendix A.
3.1 Lysimeter Construction and Installation
3.1.1 Lysimeter Construction
Each simulated landfill or “lysimeter” consists of two HDPE pipes, both 4.9 meters
tall. The larger pipe is 61 centimeters outside diameter and 57 centimeters inside
diameter (22 inches), standard dimension ratio (SDR) 32.5. The smaller pipe is 8.9
centimeters in outside diameter and 7.8 centimeters inside diameter (3.1 inches), SDR 17
(see Figure 3-1). The larger pipe contains waste through which water is percolated, and
18
the smaller pipe provides pump access to the resulting leachate via a connection at the
bottom of the lysimeter. An HDPE plate is butt-welded to the bottom of the larger pipe,
and an elbow joins the smaller pipe to the larger. At the top of the lysimeter, another
HDPE plate forms the removable lid of the larger pipe and a threaded plug seals the
smaller pipe. A drawing of the lysimeter design is shown in Figure 3-1. A local
manufacturer (Lane Piping and Equipment Company, Lakeland Florida) fabricated the
lysimeters. Detailed information and photographs of the lysimeter construction are
included in Appendix A.
Figure 3-1. Construction detail of top and bottom of lysimeter
3.1.2 Lysimeter Installation
Twelve lysimeters were installed in February 2004 as part of a Florida Center for
Solid and Hazardous Waste Management (FCSHWM) project, which investigated the
effect of certain potentially hazardous wastes on leachate quality. The lysimeters were
installed at the Polk County North Central Landfill (NCLF) near Winter Haven, Florida.
The Class I landfill accepts residential, commercial, and industrial waste in a county of
Ball valves
Ball valve 4.9 meters (16 feet)
0.6 meters (2 feet)
8.9 cm (3.5 inches)
Male NPT plug Lid
19
approximately 500,000 people. To maintain actual landfill temperatures, a contractor
buried the lysimeters inside the landfill using a 0.9 meter (3 foot) diameter bucket auger
to excavate 4.6 meter (15 foot) deep holes. Prior to burial, Omega type T (EXPP-T-20)
thermocouple wires were attached to the bottom of each lysimeter. Two of the lysimeters
were also fitted with thermocouples every 0.8 meters (2.7 feet) starting from the bottom.
The empty lysimeters were lowered into the hole using a winch on the bucket auger drill
rig, and the space around the lysimeters was backfilled with sand. Once the lysimeters
were in place, PVC ball valves (Asahi ¼” NPT labcocks) were installed per Figure 3-1.
3.2 Waste Preparation and Lysimeter Loading
Six of the twelve lysimeters were used for this study. One was filled with waste
excavated by the bucket auger. This lysimeter is referred to as the “excavated waste”
lysimeter. Two lysimeters, “control lysimeters,” contained only a synthetic waste
mixture. Three lysimeters, “E-waste lysimeters,” contained the synthetic waste mixture
and approximately 6% electronics waste by field weight (Table 3-1).
3.2.1 Excavated Waste Preparation
The excavated waste was selected from the material removed by the bucket auger.
The drilling contractor placed the excavated waste in a roll-off container. The
researchers selected waste that appeared to be dry and poorly degraded, and stored the
waste in 110 liter (30 gallon) plastic trash cans.
3.2.2 Synthetic Waste Preparation
The composition of the waste mixture was based on MSW composition data from
the literature and a waste composition study conducted at the Polk County North Central
Landfill (Franklin Assoc., 2003, FDEP, 2000). Figure 3-2 shows the composition used to
calculate the recipe for the synthetic waste.
20
Table 3-1. Lysimeter name, contents, mass of synthetic waste, E-waste and water on field weight basis, and lysimeter density
Lysimeter Contents Mass of Contents
Lysimeter Density
Excavated Waste
Waste excavated from the Polk County North Central Landfill
863 kg 750 kg/m3
Control 1 Synthetic waste 380 kg 520 kg/m3
Water 188 kg
Control 2 Synthetic waste 398 kg 540 kg/m3 Water 189 kg
E-waste 1 Synthetic waste 389 kg 538 kg/m3 E-waste 25.3 kg Water 190 kg
E-waste 2 Synthetic waste 385 kg 548 kg/m3 E-waste 25.5 kg Water 190 kg
E-waste 3 Synthetic waste 387 kg 552 kg/m3 E-waste 25.4 kg Water 190 kg
The materials, percent composition, source, and preparation of the waste mixture
are presented in Table 3-2. The waste composition from the literature is presented on a
field-weight basis. The ingredients on hand were generally drier than wastes in waste
composition studies, so the values were adjusted. The synthetic waste mixture
percentages were used for mixing the appropriate proportion of the specific ingredients
used in this study.
A fixed hammermill grinder (Packer 2000) with an 8 centimeter (3 inch) grate was
used to grind the mixed paper and cardboard (see Figure A-1). A manufacturer of plastic
lumber provided chipped acrylonitrile-butadiene-styrene (ABS) and HDPE plastic.
21
Figure 3-2. Waste composition from literature used to create synthetic waste (wet weight basis).
Food waste was simulated by Publix Grocery store vegetable waste (consisting of
49.5% (by field weight) melon, 16.8% pineapple, 16.8% corn, and 16.8% miscellaneous
vegetables), Special Kitty cat food (21% protein minimum analysis), and fish house
scraps from a local commercial fish house. The Polk County Materials Recovery
Facility, located at the Polk County North Central Landfill (NCLF) provided bales of old
corrugated cardboard (OCC), mixed paper, glass bottles, and aluminum and metal cans.
Aluminum and metal cans were flattened with a rubber-tired front-end-loader. Polk
County NCLF provided ground yard waste that appeared to have been ground in a tub
grinder with 5 to 8 centimeter (2 to 3.5 inch) diameter screen. The ground yard waste
had been stockpiled for several months, but not composted in an active manner. The
ground yard waste was being offered to residents to use as mulch.
Mixed paper 29.4%
Food waste 19.0%
Cardboard 18.4%
Plastic 16.0%
Wood 3.7%
Steel cans 4.2% Glass 4.2%
Aluminum 1.1%
Yard waste 4.0%
22
The Alachua County transfer station provided ground wood pallets that also
appeared to have been ground in a tub grinder with 5 to 8 centimeter (2 to 3.5 inch)
diameter screen. The ground wood pallets had been stockpiled for approximately one
month and very little if any decomposition had occurred. Ground wood pallets were
further processed by removing fines passing through a 2.5 centimeter (1 inch) trommel
screen provided by Sumter County Solid Waste Division.
Table 3-2. Materials used for simulated waste, source, preparation and percent composition, field weight basis
Material Composition from literature
Synthetic waste composition for mixing
Source Preparation
Mixed paper
29.4% 26.1% MRF, newsprint, magazines, phone books
Packer 2000 grinder
Food waste
19.0% 23.6% 11.5% grocery store vegetable waste 9.2% Cat food 2.9% Fish from local commercial fish house
None
Cardboard 18.4% 16.4% MRF, OCC Packer 2000 grinder
Plastic 16.0% 16.2% Local recycler, chipped hard plastics
None
Glass 4.2% 4.7% MRF, bottles Broken by front-end-loader
Steel can 4.2% 4.4% MRF Flattened by front-end loader
Yard waste
4.0% 3.3% Polk County NCLF None
Wood 3.7% 4.3% Alachua County transfer station, ground pallets
Retained by (larger than) 2.5 cm trommel screen
Al can 1.1% 1.1% MRF Flattened by front-end loader
MRF: Polk County Materials Recovery Facility OCC: Old corrugated cardboard NCLF: North Central Landfill
23
3.2.3 Waste Mixing
The primary concern with mixing the simulated waste was achieving a
homogenous mixture in loads that could be moved and poured into the lysimeters by two
people. Plastic wheeled 340 liter (90 gallon) trash carts were used to contain one load of
approximately 45 kilograms (100 pounds). The materials were mixed by weight using an
Adam Equipment Model CPW-100 or Pelouze Model 4030 scale. Rather than trying to
mix all the ingredients at once, the cat food and vegetable waste were mixed in a trash
bag, the mixed paper and cardboard were mixed into two trash bags, and the plastic,
glass, steel, wood, yard waste, and aluminum were mixed in recycling bins (see photos in
Appendix A). Each of these containers was mixed separately. Then the three containers
were gradually combined into one trash cart. As each cart was loaded, approximately 19
liters of water were added to each load. The water made it easier to compress the dry
paper and cardboard. In total, approximately 190 kg of water was added to
approximately 389 kg of simulated waste (see Table 3-1), resulting in a moisture content
of at least 33%, neglecting the moisture in the food waste.
3.2.4 Electronics Waste Preparation
Four sets of identical model electronic devices were gathered for this study, one set
for each E-waste lysimeter and one set for lab tests. The University of Florida Physical
Plant provided computers, keyboards, mouse devices, and smoke detectors. Polk County
NCLF provided monitors. A Tampa electronics recycler supplied four sets of cell phones
and seven sets of cell phone batteries. Smoke detectors were included with the hope that
the leachate could be analyzed for Americium, but the analytical capability was not
available. Cell phones were included because they are a growing portion of E-waste.
24
Cell phone batteries were included to evaluate the leaching behavior of cadmium. The
type, source, quantity, preparation, and mass of the E-waste used are summarized in
Table 3-3, and the detailed composition of the individual pieces of E-waste is in
Appendix C. The criteria for size-reducing the E-waste were chosen as six inches for
large pieces of plastic, circuit board, and metal so that good contact with the waste would
be achieved without dramatically increasing the surface area. Photographs of the E-waste
preparation are in Appendix A.
Table 3-3 Type and source of electronics waste used in this study. The number of devices included in each lysimeter and the mass in the lysimeters is shown as a range where necessary.
Type Source Preparation # per set Mass in lysimeters
Central Processing Unit (CPU)
UF Physical Plant Disassembled, Cut into 6 inch squares
1 9.2-9.4 kg
Keyboard UF Physical Plant Disassembled, Cut in half
1 1.1 kg
Mouse UF Physical Plant Disassembled 1 0.1 kg Cathode Ray Tube (CRT) Monitor
Polk County North Central Landfill
Disassembled, CRT broken by sledgehammer Plastic cut into 6 inch squares
1 12.6-12.7 kg
Cell Phones
Tampa Electronics Recycler
Disassembled 4 0.47-0.48 kg
Cell Phone Batteries
Tampa Electronics Recycler
Disassembled, Cut into half using bolt cutters
7 1.06-1.07 kg
Smoke Detectors
UF Physical Plant Disassembled 3 0.60 kg
3.2.5 Lysimeter Loading
Rinsed river rock, 5 to 8 centimeters (2 to 3 inches) in diameter, was placed at the
bottom of all lysimeters, except for the E-waste 3 lysimeter as drainage media and to
provide leachate storage. On top of the river rock, rinsed pea gravel, 0.6 to 2.5
25
centimeters (1 to 0.25 inches) in diameter, was placed to help keep the waste from falling
into the river rock. Ten centimeters (4 inches) of river rock was placed in the bottom of
each lysimeter, followed by 10 centimeters (4 inches) of pea gravel. In the E-waste 3
lysimeter, 10 centimeters (4 inches) of stacked triplanar geonet was used for leachate
storage, covered with three layers of geofabric overlain by a 10 centimeter (4 inch) sand
drainage layer. The sand drainage layer was intended to simulate the leachate collection
system in the bottom of a modern MSW landfill.
Once the synthetic waste was mixed and the drainage material was in place, waste
was added. The excavated waste lysimeter was filled in 20 loads. The control and
E-waste lysimeters were filled with 10 loads. The excavated waste was much denser that
the synthetic waste and compacted more easily. After each load, the waste was
compacted by repeatedly dropping a compaction device of approximately 35 kilograms
(80 pounds). The compaction device was a bucket of rocks attached to a wooden plate,
designed to distribute the impact evenly (see Appendix A). The thickness of each
compacted lift was measured to achieve a consistent density of approximately 524
kilograms/cubic meter (880 pounds/cubic yard) for the control lysimeters. A slightly
higher density was achieved in the E-waste lysimeters from the addition of the E-waste.
Photographs of the loading process and the compaction device are included in Appendix
A.
3.2.6 Placement of E-waste
In the experimental lysimeters, E-waste devices were placed in the middle of the
lift starting in the third lift. A schematic of the placement of the E-waste is shown in
Figure 3-3. One-third to one-half of the load of synthetic waste was added to the
lysimeter, and then the E-waste was added. The E-waste was arranged evenly across the
26
lysimeter using a long PVC pipe. Using the PVC pipe, the E-waste was mixed and
tamped into the synthetic waste to ensure good contact. Photographs of the E-waste in
the lysimeters are in Appendix A. The rest of the load of synthetic waste was added on
top of the E-waste and the lift was then compacted. The order of E-waste placement,
from the third lift to the top of the lysimeter, was: smoke detectors, CPU, CRT monitor,
keyboard and mouse, and cell phones and Ni-Cd batteries. The top three lifts of waste
contained no E-waste.
3.2.7 Water Distribution System
The water distribution system was designed to minimize short-circuiting of the
leachate. Irrigation tubing was arranged in a spiral to apply water over the entire surface
of the waste, except the outermost 5 to 8 centimeters (2 or 3 inches) (see Appendix A).
The tubing was connected to the inside of one of the ball valves in the lid of the lysimeter
with approximately 6 feet (1.8 meters) of excess tubing inside the lysimeter to
compensate for settlement. To supply water, 1 centimeter (3/8 inch) vinyl tubing was run
from the bottom of a 110 liter (30 gallon) trash can to the outside of the ball valve to
allow water to drain gradually. Water addition took from 30 minutes to 2 hours,
depending on the lysimeter and the amount of water used. The lids of the lysimeters
were sealed using 100% silicone caulk. A thick bead of caulk was applied around the top
of the lysimeter (see Appendix A) then the lid was gently put in place, forming the caulk
into a gasket-like position between the pipe and the lid. The quality of the seal was
determined by gas sampling. If oxygen was detected at significant levels (over a few
percent) higher than the previous measurement, the lid was removed and sealed again.
27
Figure 3-3. Placement of E-waste in Lysimeters. E-waste was placed approximately in
the middle of the lifts indicated above with no E-waste in the bottom two or top three lifts.
3.3 Lysimeter Operation
3.3.1 Water Addition
Water was added to the lysimeters on a regular schedule, generally every one or
two weeks. The water source was the municipal supply in Polk County and was allowed
to dechlorinate by sitting outside for at least a week in the trash cans with the lids on.
The amount of water added was determined gravimetrically.
River Rock
Smoke Detectors
CPU
Monitor
Keyboard and Mouse
Cell Phones and Ni-Cd Batteries
Waste Lift
Waste Lift
Waste Lift
Waste Lift
4.9 meters(16 feet)
0.6 meters(2 feet)
28
A number of factors, including travel schedules, the amount of leachate produced,
and the volume of sample needed, determined the volume of water added to each
lysimeter. Water was added from July 12, 2004 to July 7, 2005. In that period, 684 to
971 liters of water were added on 25 to 30 occasions, depending on the lysimeter. The
cumulative volume of water added to each lysimeter is presented in Figure 3-4. Similar
volumes of water were added to all lysimeters up to approximately Day 200, at which
time approximately 400 liters of water had been added. From Day 200, the rate of adding
water was increased. After the rate increase, the amount of leachate produced required a
reduction in water addition to some of the lysimeters. Specifically, flooding during a
storm added extra water to E-waste 2, leading to extra leachate. Also, the sand layer in
the bottom of E-waste 3 caused the leachate to drain into the collection pipe more slowly.
As a result of suspected waterlogging in E-waste 3, water was added more slowly after
Day 227. The excavated waste lysimeter also drained more slowly, and as a result, it
received the least amount of water.
3.3.2 Leachate Collection
Leachate was collected 51 times for all lysimeters except E-waste 3 (52 times) and
excavated waste (41 times) from July 12, 2004 to July 7, 2005. Approximately 800 liters
of leachate were collected from all lysimeters, except E-waste 3 (602 liters) and
excavated waste (473 liters). The procedure for leachate collection was to measure the
depth of the leachate using a Heron Little Dipper, then pump leachate into a bucket using
a 12-Volt DC pump (Whale Water Systems, GP8815 or GP9216). The bucket was
weighed full then empty to measure the leachate removed. Any samples for lab analysis
were collected directly from the pump tubing.
29
Days Since Water Addition0 50 100 150 200 250 300 350 400
Wat
er A
dded
(L)
0
200
400
600
800
1000
1200
Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 3-4. Cumulative volume of water added to lysimeters.
Field parameters were measured either in the bucket or in the sample bottles using
an Accumet AP62 pH meter with automatic temperature correction, a Hanna Instruments
HI 9033 multi-range conductivity meter, and an Accumet AP62 pH/mV meter with an
oxidation reduction potential (ORP) electrode. All meters and probes were calibrated in
the field prior to use. The ORP probe was calibrated using Thermo Orion ORP standard.
The leachate temperature was measured throughout the experiment, but different
instruments were used. Also, the method of measuring the temperature changed.
Initially, the leachate temperature was measured in the bucket. When ambient
temperatures were cool, the leachate cooled quickly, skewing the measurement. Finally,
the temperature probe was inserted into the vinyl tubing as the leachate was pumped out.
This technique resulted in measured leachate temperatures that were usually within 0.1°
30
C of the thermocouple measurement. As a result, only the thermocouple data are
presented.
3.3.3 Gas Sampling
Gas was sampled using the valves in the lysimeter lid and in the leachate collection
pipe. Gas analysis for methane, oxygen, and carbon dioxide was conducted in the field
using a GEM 2000 gas meter. Field calibration was performed as needed. Methane gas
composition was used to indicate methanogenic activity and the prevalence of
methanogenic conditions. The gas composition was also used to check for leaks of
atmospheric gases into the lysimeters. Gas was sampled on thirteen occasions during the
experiment.
3.3.4 Settlement Measurement
Settlement was measured by inserting a steel rod through one of the ball valves in
the lid of the lysimeter, noting the depth and measuring the length of the rod with a
measuring tape. The settlement is calculated from the initial depth of the waste,
measured on June 28, 2004. Settlement was measured six times during the experiment.
3.3.5 Temperature Measurement
Temperature readings were taken by thermocouples throughout the experiment.
After initial measurements, the temperature was found to be stable and in the expected
range so thermocouple readings were taken infrequently. The leachate temperature
correlated well with the thermocouple readings when the thermometer for leachate was
working properly.
31
3.4 Laboratory Methods
3.4.1 Leachate Analysis
Leachate samples were taken to the lab in coolers packed with ice at the landfill
with the exception of metals samples, which were kept at ambient temperature until
filtration due to the occasional formation of precipitate when put on ice. Preservation and
filtration were conducted at the lab. Leachate samples were analyzed for general water
quality parameters: alkalinity, total dissolved solids (TDS), non-purgeable organic carbon
(NPOC), chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD),
ammonia, sulfides, chloride ion, volatile fatty acids (VFAs), and 24 elements including 6
of the 8 RCRA metals (arsenic, barium, cadmium, chromium, lead, and silver, excluding
selenium and mercury). Elemental analysis was conducted according to EPA Method
6010B using inductively coupled plasma-atomic emission spectrometry (ICP-AES)
(Thermo Electron Corporation, Trace Analyzer). Quality assurance and quality control
was conducted according to EPA Methods 6010B and 3010A, including matrix spikes
and digestion blanks. The detection limit for lead was 0.004 mg Pb/L. A summary of the
leachate analysis is included in Table 3-4.
Metals samples, which were collected in 1-liter acid-rinsed plastic bottles, were
pressure filtered through a 7.0-µm glass fiber TCLP filter, then preserved with nitric acid
to a pH less than 2. Liquid metals samples were digested using EPA Method 3010A,
with the following modifications: 50 mL of the leachate were used due to the high
organic content of the samples. The final volume of the digestion was also 50 mL, and
ribbed watch glasses were used throughout the procedure. Alkalinity samples were
collected in plastic bottles and refrigerated. For anion and TDS analysis, aliquots from
the alkalinity bottles were diluted with 4 parts deionized water to 1 part leachate and
32
vacuum-filtered through 0.45-µm cellulose nitrate filters. The COD samples, collected in
acid-rinsed amber glass bottles, were preserved with concentrated sulfuric acid to a pH
less than 2. Aliquots for NPOC, ammonia, and VFAs were taken from the COD sample
bottle. The BOD samples were collected in plastic bottles. Sulfides samples were
collected in EPA vials. All bottles were filled with as little air space as possible. Quality
assurance and quality control measures included the routine use of blanks, duplicates, and
spikes.
Table 3-4. Leachate analysis and methods Field Data Method Sampling Date Gregorian Calendar Leachate Height Heron Instruments Little Dipper Leachate Volume Gravimetric
Adam Equipment CPW 100 Volume of Water Added Gravimetric
Adam Equipment CPW 100 pH Accumet AP62 Oxidation-Reduction Potential (ORP) Accumet AP62 Conductivity Hanna Instruments HI 9033 Lab data Leachate lead Digestion: EPA SW 846 3010B
Analysis: ICP-AES EPA SW 846 6010B
Total Dissolved Solids (TDS) Standard methods 2540C Alkalinity Standard methods 2320C Biochemical Oxygen Demand (BOD) EPA 405.1 Chemical Oxygen Demand (COD) Hach DR/4000, Hach method 2720 Non-Purgeable Organic Carbon (NPOC)
Rosemont TOC Analyzer
Ammonia Ammonia Probe Sulfides Hach DR/4000 Chloride ion Dionex DX500 IC
US EPA-SW 846 Method 9056 VFAs (Acetic, Propionic, Isobutyric, Butyric, Isovaleric, Valeric, Isocaproic, Hexanoic, Heptanoic)
Liquid to Solid Ratio (L:S) Calculated
33
3.4.2 Solid Digestion of Synthetic Wastes
Solid samples of the components of the synthetic waste were digested using EPA
SW 846 Method 3050B. Samples were digested in six replicates. Aluminum and steel
cans were cut into strips weighing approximately 1 gram using a metal shear. The strips
were cut thinly enough so that the samples included all portions of the cans: the sides,
seams, and top or bottom. Mulch and ground wood pallets were ground to less than 3
millimeters using a Fritsch Pulverisette® 19 cutting mill, and 1 gram samples were taken
from the sawdust. Mixed paper, cat food, cardboard, and plastic did not require
processing to obtain a 1 gram sample. The other sources of food waste, such as
vegetables and fish-processing waste, were not digested because of the heterogeneous
nature of the material. Where necessary, the digestate was diluted after digestion to bring
the concentrations of the elements into the working range of the ICP-AES.
3.4.3 Data Analysis
Data were maintained using Excel and SigmaPlot. Statistical analysis of these data
is focused on finding correlations between leaching parameters and determining if the
leaching of lead is greater in the E-waste lysimeters than in the control lysimeters. Also,
the total mass of lead leached from each lysimeter is of major interest. The total mass of
lead leached was calculated by multiplying the concentration of lead by the volume of
leachate produced since the previous lead sample for each lead sample, then summing the
values. The weighted average lead concentration was calculated by dividing the total
mass of lead leached by the total volume of leachate produced. The concentration of lead
in the leachate was compared between lysimeters using tests of means, student’s t-test
and analysis of variance (ANOVA). Excel was used for student’s t-test and ANOVA.
Limitations of comparing the means of these data are discussed in Chapter 4.
34
CHAPTER 4 RESULTS
Before the lead data can be discussed, the leachate quality and physical parameters
of the lysimeters should be considered. The intent of the study was to expose E-waste to
simulated MSW landfill conditions. To assess how well the MSW landfill conditions
were achieved, a number of parameters are discussed below. The lysimeter containing
excavated waste also provides insight into how actual landfilled MSW behaved in this
lysimeter experiment.
4.1 Lysimeter Leachate Data
4.1.1 Lysimeter Leachate Data Compared to Typical Landfill Conditions
The manner in which landfill conditions change as waste decomposes was
discussed in Chapter 2 and summarized in Figure 2-1. For this study, the most important
phases of waste decomposition were the acid phase and the methanogenic phase. The
parameters that can be used to characterize these phases are the leachate pH, dissolved
organic matter, and redox potential, along with the percent of methane gas present.
Methane and pH were measured directly. Dissolved organic matter was quantified using
chemical oxygen demand (COD), biochemical oxygen demand (BOD), non-purgeable
organic carbon (NPOC), and volatile fatty acids (VFAs). The discussion here focuses on
COD and NPOC; BOD and VFA data are presented in Appendix B and Appendix C.
The leachate pH is a very important indicator of the phase of decomposition and
the type of microbial activity present. In landfills, pH is controlled by the carbonate
buffering system interacting with minerals, organic compounds, and dissolved gases
35
(Vesilind et al. 2002). As discussed in Chapter 2, during the acid phase, organic acids,
H2 gas, and CO2 gas contribute to the decrease in pH. As the waste transitions to the
methanogenic phase and organic acids and H2 gas are consumed, the pH increases to the
neutral range (Tchobanoglous et al., 1993).
The trend of leachate pH is presented in Figure 4-1. The pH of the control and
E-waste leachates remained in the acidic range for the entire experiment, and all
stabilized around a pH of 5. The pH of the excavated waste leachate was 5.12 initially
and increased quickly. The excavated waste leachate stayed above 6.5 after Day 143,
reaching a maximum of 8.11 and stabilizing around 7.2. In terms of the amount of
leachate produced, the acidic phase for the excavated waste was brief. Only 39.9 liters of
leachate were collected by Day 143, the first day the excavated waste leachate pH stayed
over 6.5.
The excavated waste experienced a shorter acid phase than the control and E-waste
lysimeters. This could be because it had been buried in the landfill for approximately
three years and readily decomposable compounds should have been consumed. Factors
that may have influenced the decomposition of the excavated waste include: the particle
size of the waste was reduced by the excavation, trash bags were broken, and in the
lysimeter, the waste was less compacted and much moister than in the landfill.
The leachate NPOC and COD are indicators of the organic matter in the leachate.
The NPOC is a more direct measure of organic matter since COD measures compounds –
both organic and inorganic – that can be oxidized using a chemical oxidizing agent.
However, for the purpose of comparing the lysimeters to landfill leachates, COD is a
better choice as COD is more widely cited than NPOC in previous landfill leachate
36
studies. At the high levels of organic materials in the leachates, the method for analysis
for both COD and NPOC are more robust than the methods used for BOD and VFAs.
The data for BOD and VFAs are included in Appendix C.
Leachate COD and NPOC follow a similar trend. The leachate COD values began
in the acidic range, increased, and then decreased gradually. Leachate NPOC is shown in
Figure 4-2 and COD is shown in Figures 4-3 and 4-4. Only the leachate from the
excavated waste lysimeter reached the range of COD typical of the methanogenic phase.
The excavated waste lysimeter COD started around 20,000 mg/L and increased to a
maximum of 85,000 mg/L. Then, coinciding with the increase in pH, the COD decreased
and stabilized around 1,300 mg/L (better seen in Figure 4-4 where COD is expressed on a
log scale). The maximum COD values for the control and E-waste lysimeters were
higher than the excavated waste, ranging from 95,000 to 110,000 mg/L. The COD for
the control and E-waste lysimeters decreased and stabilized around 10,000 to 15,000
mg/L. The COD levels in the lysimeter leachates were within the ranges described by
Kjeldsen et al. (2002) (140 mg/L to 152,000 mg/L), but very high compared to acidic
phase landfill leachates described by Ehrig (1988).
Compared to the typical landfill conditions described in Chapter 2 and Figure 2-1,
the leachates did not exhibit earlier phases of decomposition. The pH values are very
low, and the COD values are elevated even at the beginning of leachate collection. One
possible explanation is that these phases occurred, but no leachate was produced. The
delay between water addition and leachate collection was about 45 days for the control
and E-waste lysimeters, and 83 days for the excavated waste lysimeter. During that time,
decomposition would occur in the lysimeters, especially the control and E-waste
37
lysimeters which received water as they were filled, at least 33% on a wet weight basis.
While the moisture content of the excavated waste was not determined, it appeared dry
but was not dusty.
The means of the lysimeter leachate pH and COD values are presented Table 4-1
and compared to MSW landfill leachate ranges from Ehrig (1988). The means for the
control and E-waste lysimeter leachates fell within the ranges reported for the acid phase.
The excavated waste leachate data are divided into samples with a pH less than 6.5 and a
pH greater than 6.5. Excavated waste methanogenic leachate (pH greater than 6.5) had a
mean COD somewhat higher that the range given by Ehrig (1988). But as seen in Figure
4-4, the COD dropped within the range around Day 250.
Table 4-1. Lysimeter leachate pH and COD compared to literature values for acidic and methanogenic conditions from Ehrig (1988)
Parameter pH COD (mg/L) Landfills phase-specific Acidic1 Methanogenic1 Acidic 1 Methanogenic1
4.5-7.5 7.5-8.5 6,000-60,000 500-4,500 Lysimeter Lysimeter leachate mean values Control 1 5.17 39,000 Control 2 5.11 45,000 E-waste 1 5.19 41,000 E-waste 2 5.14 41,000 E-waste 3 5.25 50,000 Excavated waste–pH < 6.5 5.91 59,000 Excavated waste–pH > 6.5 7.37 8,500 1 (Ehrig, 1988)
Oxidation Reduction Potential (Eh) is difficult to interpret as the response of Eh
probes is sensitive to a number of factors, including changes in the leachate composition
over time. However, some broad observations can be made based on the Eh data. The
Eh should be lower – more reducing – in the methanogenic phase than in the acidic
phase. The Eh for the lysimeter leachate is shown in Figure 4-5. The Eh data prior Day
120 was unreliable because the probe was not calibrated properly. For the excavated
38
waste lysimeter, the Eh at Day 120 was much lower than the other lysimeters and
increased slowly. In the control and E-waste lysimeters, the Eh fluctuated lower around
Day 300. This could mean a gradual change from the acidic phase to the methanogenic
phase.
While the leachate parameters give an idea of the conditions at the bottom of the
lysimeter, the lysimeters did not become methanogenic all at once. Waste is a
heterogeneous substrate, and different phases of decomposition developed in the same
lysimeter. In addition to the typical microbial heterogeneity, methanogenic conditions
became more prevalent at the top of the lysimeter. The addition of water to the lysimeter
flushed organic acids from the waste and increased the pH, providing better conditions
for methanogens. As methanogens became more prevalent, the leachate passing to the
underlying waste became more neutral in pH, spreading the methanogenic conditions
downward. However, if the bottom of the lysimeter remained acidic, the leachate would
be typical of the acid phase.
A way to assess the prevalence of methanogenic conditions is to measure the
percent methane in the lysimeter gas. Methane measurements started Day 127 (see
Figure 4-6). On Day 127, the excavated waste lysimeter methane composition was over
55%, which was maintained for the rest of the experiment, indicating good methanogenic
conditions even though the leachate pH was 6.24 and the COD was 85,000 mg/L. The
control and E-waste lysimeter methane compositions were between 10% and 25%
methane on Day 127. By Day 350, the control and E-waste lysimeter methane
concentrations approached 50% even though the pH and COD values did not change.
From an operational standpoint, the gas composition was used to confirm the air-
39
tightness of the lids. For instance, the decrease in methane concentration in E-waste 2
around Day 230 was remedied by resealing the lysimeter lid.
Methane concentration increased before the leachate parameters changed from
acidic to methanogenic, and it is considered an early indicator of the transition between
phases. Also, the methane composition reflected the order in which the lysimeters were
filled; the lysimeters with more methane were filled first. The lysimeters that were filled
last, E-waste 2 and E-waste 3, were consistently the lowest in methane concentration and
had the highest maximum COD values.
In conclusion, the lysimeter parameters were generally typical of values from
landfills. The excavated waste lysimeter proceeded through phases typical of the acid
and methanogenic phase. The control and E-waste lysimeters remained in the acid phase
for the duration of this study. In fact, the leachate pH and COD values for the control and
E-waste lysimeters were near the extremes of reported landfill values. The lysimeter
leachates should have better simulated acid-phase leachate than the TCLP. The pH of the
TCLP extraction fluid used for E-waste was 4.93 +/- 0.05 and the acetate concentration
was 5,990 mg/L (Jang & Townsend, 2003). In the leachates from the control and
E-waste lysimeters, the average pH ranged from 5.11 to 5.25, and the acetic acid
concentrations ranged from 1,800 to 17,000 mg/L and averaged 7,700 to 12,000 mg/L.
Compared to typical acid-phase landfill conditions or the TCLP, the lysimeter leachate
may have been a more aggressive leaching fluid.
The acid phase lasted longer than anticipated. There are probably several reasons
for this extended acid phase. The simulated waste was intended to simulate the waste
stream entering landfills rather than waste streams successfully used for anaerobic
40
conditions. Also, the mixture did not consider the potential impact of soil as a relatively
inert component of MSW landfills. These factors resulted in a mixture of waste that was
higher in decomposable material than may have been optimal for the quick transition to
the methanogenic phase. From an operational standpoint, the lysimeters were intended to
be sealed air-tight and operated anaerobically. This is not typical of landfill conditions.
Waste normally is exposed to oxygen before it becomes anaerobic. This allows the most
putrescible wastes to decompose at least somewhat aerobically, reducing the potential for
acid production in the future. In some lysimeter studies, the top of the lysimeter is open
to the atmosphere, or air is forced through the lysimeter to shorten the acid phase.
Overall, the effect of the extended acid phase should increase the leachability of lead
relative to typical landfills or the excavated waste lysimeter.
Days Since Water Addition
0 50 100 150 200 250 300 350 400
pH
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Methanogenic
Acidic
Figure 4-1. Leachate pH versus time. Ranges for the acidic and methanogenic phases
reported in landfills are indicated by arrows.
41
Days Since Water Addition
0 50 100 150 200 250 300 350 400
NPO
C (m
g/L)
0
5000
10000
15000
20000
25000
30000
35000
40000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 4-2. Lysimeter leachate NPOC versus time.
Days Since Water Addition
0 50 100 150 200 250 300 350 400
CO
D (m
g/L)
0
20000
40000
60000
80000
100000
120000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Methanogenic
Acidic
Figure 4-3. Leachate COD (linear scale) versus time. Ranges for the acidic and
methanogenic phases reported by Erhig (1988) in landfills are indicated by dashed lines.
42
Days Since Water Addition
0 50 100 150 200 250 300 350 400
CO
D (m
g/L)
100
1000
10000
100000
1000000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Methanogenic
Acidic
Figure 4-4. Leachate COD (log-scale) versus time. Ranges for the acidic and
methanogenic phases reported by Erhig (1988) in landfills are indicated by dashed lines.
Days Since Water Addition
0 50 100 150 200 250 300 350 400 450
Eh (m
V)
-200
-100
0
100
200
300Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 4-5. Lysimeter leachate Eh versus time.
43
Days Since Water Addition
0 50 100 150 200 250 300 350 400
CH
4 %
0
10
20
30
40
50
60
70Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 4-6. Lysimeter methane concentrations versus time.
4.1.2 Lysimeter Lead Concentrations
The most straightforward approach to examine the leaching of lead is to compare
the leachate lead concentration versus time between the different lysimeters. This
approach is somewhat limited, as it neglects any differences in the volume of leachate
collected. Another approach is to compare the concentration data in relation to the
amount of leachate eluted per mass of waste in the lysimeter, or the liquid-to-solid ratio
(L/S ratio). This allows the data to be normalized for both the volume of leachate and the
mass of waste. The most useful comparison is the total mass of lead leached from each
lysimeter. This combines the concentration and leachate volume data and can be
presented as a function of time or L/S ratio.
The mass of lead leached from the lysimeters is just one component of the study.
One of the reasons for using a simulated waste mixture was to ascertain the sources of
44
lead in the leachate. To help determine potential sources of lead, each component of the
simulated waste was digested and analyzed for metals. Also, the total mass of lead in the
E-waste was estimated using literature values.
The concentration of lead in the lysimeter leachates is presented in Figure 4-7. The
highest concentrations were found in the excavated waste leachate, which reached the
maximum on Day 106 at 0.16 mg Pb/L. The control and E-waste lysimeters were all
below 0.07 mg Pb/L. The excavated waste lysimeter exceeded all other concentrations
for five weeks, and then dropped below the other lysimeters by Day 150. As the
lysimeter became methanogenic, the COD decreased to 25,500 mg/L, and the leachate
pH increased to 7.82. The lead concentration in the excavated waste leachate follows the
trend of the leachate COD more closely than the pH trend.
It was surprising that the highest concentrations of lead were in the excavated waste
leachate. One possible explanation is that the excavated waste contained more lead.
Regardless of the amount of lead in the excavated waste, another possibility is that the
form of lead in the excavated waste was more readily leached than the lead in the other
lysimeters. The chemical or physical changes in the excavated waste from the excavation
process could have made the lead more mobile. The waste in the landfill was likely
under reducing, anaerobic conditions, then excavated and stored aerobically, and finally
placed in the lysimeter. Dissolved lead species formed in the landfill could have
precipitated or adsorbed to the excavated waste. The lead precipitates could be more
mobile than the original lead because of the nature of the compound, the amount of
surface area per mass, or the ability for small particulates and colloids to move with the
leachate. Adsorbed lead could be more mobile as a result of the drying of the waste.
45
Finally, the excavation and handling of the waste could have physically exposed new
material or otherwise made lead leach more easily.
Another way of looking at the concentration data is in relation to the liquid-to-solid
ratio (L/S ratio). The L/S ratio is calculated by dividing the mass of leachate collected by
the mass of material in the lysimeter. The value used for mass of material includes the
synthetic waste, E-waste, and water added during mixing. Enough water was added to
bring the lysimeters to at least 33% moisture. The dry weight of all the synthetic waste
components was not known so the L/S ratio on a dry weight basis was not calculated.
Because the amount of waste used in each lysimeter is similar, the trends will appear the
same whether the L/S ratio is on a dry or wet basis or if the data are plotted against
leachate volume. Figure 4-8 shows the leachate lead concentration as a function of the
L/S ratio. The effect of flooding in E-waste 2 can be seen because the initial sample was
collected at an L/S ratio of 0.18. The trend for E-waste 2 is shifted rightward on the L/S
ratio axis, but otherwise appears to follow the other trends. The initial high lead
concentrations in the excavated waste leachate clearly occur at very low L/S ratios,
briefly in terms of the amount of leachate produced. Only 39.9 liters eluted before the
lead concentration in the excavated waste leachate dropped below the others. This is one
reason why simply comparing the lysimeters using averaged concentration data would be
inappropriate.
The lead concentration data are presented as a box-and-whisker plot in Figure 4-9.
The dashed line in the box and whisker plot indicates the mean, and the solid line the
median, the edges of the box are the 25% and 75% percentiles, the whiskers the 10% and
90% percentiles, and the dots are the outliers. The 0.015 mg Pb/L drinking water action
46
limit is plotted as a dotted line. Since the excavated waste lysimeter leachate changed
from the acidic to the methanogenic phase, those data are divided into two boxes, one for
leachates with a pH higher than 7 and one for leachates with a pH lower than 7.
The difference between the two groups of excavated waste data is clear. The acidic
phase excavated waste leachate had a mean concentration of 0.11 mg Pb/L. The
methanogenic phase excavated waste leachate had the lowest mean, 0.0084 mg Pb/L,
below the drinking water action level. As noted earlier, the value of this comparison is
limited. What is significant is how much lower the lead concentrations are in the
methanogenic phase leachate compared to the acidic phase leachate in the excavated
waste lysimeter and the control and E-waste lysimeters. A similar decrease in lead
concentrations can be expected when the other lysimeters enter the methanogenic phase.
The overall effect of adding E-waste is unclear based on the lead concentration
data. To see the total amount of lead leached from the lysimeters, the cumulative mass of
lead leached is calculated and plotted against the L/S ratio in Figure 4-10. E-waste
lysimeters leached a greater mass of lead than any of the other lysimeters. E-waste 1,
E-waste 2, and E-waste 3 leached 24.4 mg, 23.9 mg, and 24.6 mg, respectively. Control
1 and control 2 both leached 19.9 mg (see Table 4-2). The cumulative lead leached for
E-waste 2 appears to be shifted rightward due to flooding that occurred in August 2004.
Control 1 leached 15.9 mg of lead. The excavated waste lysimeter, which had the highest
lead concentrations, leached the least mass of lead at 6.95 mg.
The mass of cumulative lead leached increases at about the same rate for the
control and E-waste lysimeters until the L/S ratio reaches 0.4. Operational changes in the
amount of water which was added resulted in a slower water addition rate being used for
47
E-waste 3 after L/S ratio of 0.4. A slower water addition rate reduces the velocity of
water through the lysimeter and could lead to longer contact times with the waste. The
role of contact time with respect to leachate parameters is unclear, but may directly or
indirectly affect the leaching of lead, as the control and E-waste lysimeters with the
higher L/S ratio leached a lower cumulative mass of lead.
Table 4-2. Lysimeter leachate lead parameters Excavated
waste Control 1
Control 2
E waste 1
E waste 2
E waste 3
Total mass of lead leached as of 8/3/05 (mg) 6.95 19.9 19.9 24.4 23.9 24.6 Weighted Average (mg/L) 0.0147 0.0246 0.0240 0.0295 0.0301 0.0405 Mean (mg/L) 0.0415 0.0277 0.0283 0.0369 0.0355 0.0407 Standard Error 0.0117 0.00289 0.00276 0.00279 0.00323 0.0027 Median (mg/L) 0.0124 0.0339 0.037 0.0406 0.0367 0.0417 Standard Deviation 0.0547 0.0145 0.0138 0.0137 0.0158 0.0132 Sample Variance 0.00299 0.000209 0.000191 0.000187 0.00025 0.000175Kurtosis -0.1138 -0.7427 -1.51 -0.9915 -1.216 -0.7179
Skewness 1.243 -0.3439 -0.3872 -0.4804 -0.07259 0.1311
Range (mg/L) 0.157 0.0515 0.0425 0.0422 0.0514 0.0496 Minimum (mg/L) 0.002 0.002 0.002 0.0133 0.00664 0.0163 Maximum (mg/L) 0.159 0.0535 0.0445 0.0555 0.058 0.0659 Count 22 25 25 24 24 24 Confidence Level (95.0%) (mg/L) 0.0243 0.00597 0.0057 0.00577 0.00667 0.00559
The weighted average leachate lead concentration can be calculated by dividing the
total mass of lead leached by the total volume of leachate collected. Table 4-2 presents
this and other summary data. The mean lead concentrations are higher than the weighted
averages. The weighted average lead concentrations for the control and E-waste
leachates are above the drinking water action limit of 0.015 mg Pb/L, but much lower
than the TC limit of 5.0 mg Pb/L. The excavated waste lysimeter had the lowest
48
weighted average lead concentration, 0.0147 mg Pb/L, just at the drinking water action
limit.
The total mass of lead leached from E-waste lysimeters was 20% to 24% greater
than the mass leached from the controls. The weighted average lead concentration is
greater for the E-waste lysimeters than the control lysimeters. It was hypothesized that
the leaching of lead would be much greater in the E-waste lysimeters than the controls.
The acid-phase leaching conditions in the lysimeters were more aggressive in terms of
pH and organic compounds than most landfills. The fact that the acid phase was
extended for longer than planned raises more questions about the similar levels of
leaching in the control and E-waste lysimeters. A number of factors that may explain this
are considered in chapter 5.
Days Since Water Addition
0 50 100 150 200 250 300 350 400 450
Leac
hate
Lea
d C
once
ntra
tion
(mg/
L)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 4-7. Leachate lead concentration vs. time.
49
Liquid to Solid Ratio
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Leac
hate
Lea
d C
once
ntra
tion
(mg/
L)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 4-8. Leachate lead concentration vs. liquid to solid ratio.
Leac
hate
Lea
d C
once
ntra
tion
(mg/
L)
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
Drinking Water Action Limit
Excavated WastepH < 7
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3Excavated WastepH > 7
Figure 4-9. Box plot of leachate lead concentrations by lysimeter for entire experiment.
Excavated waste leachates with pH less than 7, solid, pH greater than 7, patterned. Dashed line is mean, center line is the median, the box is 25% and 75% and the whiskers are the 10% and 90%. Dots are outliers.
50
Liquid to Solid Ratio
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Cum
ulat
ive
Lead
Lea
ched
(mg)
0
5
10
15
20
25
30
Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure 4-10. Cumulative lead leached vs. liquid to solid ratio.
4.1.3 Statistical Analysis
To compare the means of the lead concentrations in the lysimeters the t-test and
analysis of variance (ANOVA) were used. The statistical analysis is summarized in
Table 4.3; more details are included in Appendix C. All analysis was conducted at α =
0.05 level of significance. First, the two control lysimeters were statistically similar
(P=0.875) according to the t-test. The three E-waste lysimeters were compared to one
another using single factor ANOVA. The three E-waste lysimeters were statistically
similar to one another as well (P=0.435). Finally, two-factor ANOVA with replication
was used to compare the concentrations of the two controls and E-waste 1 and E-waste 2.
E-waste 3 was excluded from the two-factor ANOVA because it differed so much from
the other lysimeters in terms of the amount of leachate collected. The variation of means
due to addition of E-waste was statistically different (P=0.011). The variation of means
between the replicates of the same treatment was not statistically different (P=0.89).
51
Tests to compare the means of leachate lead concentrations, such as the t-test and
ANOVA are robust, but have limitations for these type of data. The main limitation is
the assumption that the sample data are representative of a normally distributed
population. These data are changing over time and do not come from a normally
distributed population. Unfortunately, the weighted average lead concentrations cannot
be compared in a statistically meaningful way because of the small number of replicates.
Heterogeneity of regression analysis is a way to address the type of data produced in this
experiment. In this analysis, regression lines are fit to the data, then the regression lines
are compared for similarities. This analysis is being explored for the future peer-
reviewed publication of this study.
Table 4.3. Statistical analysis Null hypothesis: means are equal
Control 1 Control 2
E-waste 1 E-waste 2 E-waste 3
t-Test: Two-Sample Assuming Equal Variances
single factor ANOVA
tstat -0.158 F = 0.842 tcritical 2.01 Fcritical = 3.13 P = 0.875 P = 0.435 Null hypothesis is: Retained Retained two-factor ANOVA with replicates Null hypothesis: means are equal Control 1
Control 2 E-waste 1 E-waste 2
Source of variation F P-value Fcritical Null hypothesis is:
Between replicates 0.019171 0.89018 3.94 Retained Presence of E-waste 6.755119 0.010888 3.94 Rejected Interaction 0.127718 0.721628 3.94 Retained
52
4.2 Sources of Lead in Lysimeters
One important issue related to the similarity of lead leaching from the control and
E-waste lysimeters is the level of lead in the simulated waste. The chief advantage of
preparing a simulated MSW mixture is the ability to characterize the material in terms of
the lead present. The materials used to make the synthetic waste were analyzed for total
metals content in sets of at least six replicates. The concentration of lead in the synthetic
waste components is presented in Table 4-4. The major source of lead in the simulated
waste appears to be steel cans, old corrugated cardboard (OCC), plastic, and mixed paper.
Approximately 1,400 mg of lead were present in each lysimeter from the simulated
waste. Steel cans contribute 1,000 mg of lead, 190 mg are from OCC, 70 mg are from
plastic and 68 mg are from mixed paper. The mass of lead found in the synthetic waste
components was lower than found by Heck et al. (1994) in similar waste categories
collected at a Florida waste-to-energy facility.
The hypothesis is that the main source of lead in the control lysimeters and perhaps
also the E-waste lysimeters is from organically bound lead from the mixed paper and
OCC fractions. Metals bound to organic material such as wood can have increased
leachability (Van der Sloot & Dijkstra, 2004). It is suspected that the lead associated
with the mixed paper and OCC is bound with the organic substrate, and this lead is
significantly more soluble than the mineral forms of lead present in the metal cans or in
E-waste. Physical leaching mechanisms may also play a role since the leachate would
contact only the surface of the metal cans, but could saturate the mixed paper and OCC,
making more surface area available for leaching. Also, because the cardboard is
biodegradable, lead bound in the fibers would be liberated as it decomposes. Lead in the
53
cardboard may more readily bind with dissolved organics if the organics are produced by
the decomposition of cardboard.
Table 4-4. Sources of lead in synthetic waste Total extractable lead (mg/kg), standard deviation of six replicates, mass of material per lysimeter (mg), and contribution to lead in lysimeter (mg)
Material mg lead / kg of material
Standard deviation
Mass of material per lysimeter (kg)
mg lead in lysimeter from material
Mixed paper 0.67 0.349 101.1 68 Cat food 0.39 0.498 35.6 14 Fish waste and vegetable waste
NA NA 54.7 NA
Cardboard 2.9 1.249 63.3 180 Plastic 1.1 2.213 62.6 69 Glass NA NA 18.1 NA Steel can 59. 7.402 17.0 1000 Yard waste 1.1 0.307 12.7 14 Wood 0.73 0.257 16.5 12 Al can 4.5 4.779 4.3 19 Sum NA NA 385.9 1,376 Mass of material (kg) per lysimeter x mg lead / kg of material = mg lead per lysimeter
Another consideration is that if the inorganic lead in the cans is responsible for the
lead in the controls, then the inorganic lead in the E-waste would likely also leach under
those conditions. The source of the lead in the control lysimeters therefore could be the
organic fraction of the waste stream. Another possibility is that the lead leaching out of
the lysimeters originated from the simulated waste at the bottom of the lysimeter. The
mobility of lead appears to be limited and sources at the bottom of the lysimeter could be
responsible for much of the lead in the leachate. Ultimately, it is not possible to
positively determine the source of the lead from this study. One method that could be
used to determine the source of the lead is isotopic analysis of the lead in the leachate and
in the sources.
54
The addition of E-waste increased the mass of lead leached from the lysimeters.
But how significant was the increase? One way to consider the significance of the
increase in lead leached is to estimate the mass of lead in the E-waste. For the estimate
of mass of lead in the E-waste, only the CPU, monitor, and keyboard were considered as
they comprise 95% of the mass of E-waste in a lysimeter (Table 4-5). The mass of
printed wire boards in the CPU, monitor, and keyboard is multiplied by literature values
for the concentration of lead in printed wire boards (CDTSC, 2004b). The mass of lead
in cell phones was estimated by multiplying the mass of the cell phones by literature
values for lead content of cell phones, 0.43% lead (CDTSC, 2004a). The estimated mass
of lead from printed wire boards in the CPU, monitor, keyboard, and cell phones is
24,190 milligrams of lead per E-waste lysimeter. Lead in the monitor CRT is
incorporated in the CRT glass and much of it is not available for leaching. The total mass
of lead in the CRT is in the kilogram range, several orders of magnitude greater than the
other sources, so it is not added to the other totals. The CRT by itself may contain from
1.6 to 3.2 kilograms of lead (Jang & Townsend, 2003).
The mass of lead from the E-waste, 24,190 mg of lead, compares to a total of 1,384
mg of lead in the control lysimeters. The cumulative mass of lead leached can be
compared to the total mass of lead in the lysimeters to give an approximation of how
available the lead is for leaching as seen in Figure 4-11. The cumulate mass of lead
leached from the control lysimeters is approximately 70 times less than the mass of lead
in the simulated waste. The E-waste lysimeters leached on average 4.4 mg more lead
than the controls, this is more than four orders of magnitude less than the mass of lead
55
added to the E-waste lysimeters from circuit boards alone, neglecting the lead in the CRT
glass.
Table 4-5. Estimated mass of lead in E-waste lysimeters Average mass of E-waste components, estimated mg lead per kg of E-waste, and estimated mass of lead in each E-waste lysimeter from E-waste
E-waste component
Average mass of E-waste component in lysimeter (kg)
Estimated mg lead / kg of materiala
Estimated lead per E-waste lysimeter (mg)
Printed wire board-CPU 1.1 10,000 (1%) 11,000
Printed wire board-monitor 1.1 10,000 (1%) 11,000
Printed wire board-keyboard .019 10,000 (1%) 190
Cell phones 0.475 4,300 (0.43%) 2,000Sum 2.694 24,190 Cathode ray tube-Monitor 7.0 NA 1.6 - 3.2 (kg) b
a CDTSC 2004b
b Range of amount of lead per CRT, Jang & Townsend 2003
Liquid to Solid Ratio
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Cum
ulat
ive
Lead
Lea
ched
(mg)
0.1
1
10
100
1000
10000
100000
Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Total lead in control lysimeter
Total lead in E-waste
Figure 4-11. Cumulative lead leached from lysimeter compared to total mass of lead in simulated waste and E-waste.
56
CHAPTER 5 DISCUSSION
The goal of this study was to assess the leaching of lead from E-waste in simulated
landfills. This test was designed to be a conservative assessment (ie., designed to
overestimate the leaching of lead). The E-waste lysimeters contained 6% E-waste by
weight. E-waste currently makes up 1.5% of waste that is disposed of (landfilled or
incinerated) in the United States. The estimated mass of lead in the E-waste lysimeters
from circuit boards alone was 17 times the mass of lead from the simulated waste in the
lysimeters. In addition, the E-waste lysimeters provided an aggressive leaching
environment. For the control and E-waste lysimeters, the average leachate pH was 5.11,
5.17, 5.19, 5.14, and 5.25, and the chemical oxygen demand (COD) was very high
compared to typical acidic phase landfill leachate. Acetic acid concentrations for the
control and E-waste lysimeters averaged 7,700 mg/L, 10,000 mg/L, 8,500 mg/L, 9,400
mg/L, and 12,000 mg/L, much higher than in the TCLP extraction fluid.
More lead leached from the E-waste lysimeters, both in terms of lead concentration
and total mass of lead. The weighted average lead concentrations in the E-waste
lysimeter leachates were, on average 13 µg Pb/L higher than the control lysimeter
leachates, 37.7 µg Pb/L compared to 24.3 µg Pb/L. The concentrations of lead from the
control and E-waste lysimeters were statistically different at the α = 0.05 level of
significance according to ANOVA analysis. The average total mass of lead leached from
the E-waste lysimeters was 24.3 mg, 4.4 mg higher than the average mass leached from
the controls at 19.9 mg. The increase in the mass of lead leached from the E-waste
57
lysimeters was less than 0.018% of the total mass of lead in the E-waste lysimeters. The
highest concentrations of lead occurred in the excavated waste lysimeter during the acid
phase and decreased to below detection limit in the methanogenic phase.
Two reasons that more of the lead from the E-waste did not leach from the
lysimeters are; the lead did not leach from the E-waste at all, or the lead leached from the
E-waste but was not mobile in the lysimeters. Previous research has compared the
leaching of E-waste in TCLP fluid and in MSW leachate (Jang and Townsend, 2003).
The MSW leachate leached about two orders of magnitude less lead from CRT glass and
circuit boards than the TCLP fluid. In that instance, the difference in leaching was
attributed to the MSW leachate being less aggressive than the TCLP fluid. The average
MSW leachate pH was 7.60, and the acetate concentration in the samples that were
measured (about half the MSW leachates) ranged from 13 to 580 mg/L. In this case, the
lysimeter leachate is a much more aggressive leaching solution than the MSW leachates
used by Jang and Townsend (2003). The other possibility is that the lead entered the
leachate, but it was not mobile through the waste. Precipitation and sorption reactions are
two processes that could account for the removal of lead from the leachate and depend on
lead speciation.
The speciation of lead is a function of pH, redox conditions, ionic strength,
complexing compounds, and the stability of complexed compounds (EPA ORIA, 1999).
If the concentration of lead is higher than the solubility of a solid lead species,
precipitation will occur and the concentration of lead will be controlled by the solid lead
species (EPA ORIA, 1999). Under oxidizing conditions, the solids formed could be
PbSO4, Pb5(PO4)3OH, and PbCO3 (EPA ORIA, 1999). Under reducing conditions, lead
58
concentration may be controlled by galena, PbS. Where lead solubility is controlled by
galena, lead concentrations have been predicted to be less than 21 ng/L (EPA ORIA,
1999). If no lead solid minerals are present, sorption on mineral and organic solids will
control the dissolved concentration (EPA ORIA, 1999).
In the context of a batch leaching test, the liquid is always in contact with the
waste, and the only materials available for reaction are the waste and the liquid. In a
lysimeter or landfill, the waste and liquid are mixed with other materials, which provide
sites for sorption and compounds that will influence the speciation of lead. For instance,
CO2 from decomposition of organic matter makes the formation of PbCO3 more likely in
lysimeters than in the TCLP. Also, the materials in a lysimeter or landfill provide the
elements that influence the speciation of lead.
In this lysimeter test, it is likely that the majority of leached lead was precipitated.
The lead in the leachate is likely complexed to chelating agents or was bound to colloidal
matter. The mean lead concentrations were statistically different in the E-waste
lysimeters, but the increase was minor relative to the total mass of lead added to the
E-waste lysimeters. Much of the leachable lead was from the simulated waste, and the
concentration of lead was probably controlled by the chemistry of the system,
independent of the mass of lead in the lysimeters.
While the E-waste lysimeters leached more lead than the controls, was the increase
environmentally significant? To put the results in context, the second specific objective
is to compare the lysimeters to earlier lysimeters, historic landfill data, and regulatory
levels. The lysimeters are compared on the basis of the weighted average lead
concentration. Kemper et al. (1984) built five lysimeters, 2.1 meters wide, 3.4 meters
59
long, and 3.7 meters deep, to compare the effect of shredding and/or baling waste on
leachate production and quality. The lead leached per mass of waste in Kemper et al.
(1984) experiment was multiplied by the mass of waste in each lysimeter, and then
divided by the volume of leachate collected to reach the weighted average lead
concentration.
Landfill leachate data are adapted from Townsend et al. (2003) and include landfill
leachate data from Florida and other parts of the United States, from the EPA Leach 2000
database. Also, landfill leachate data are included from a survey of Florida landfills
conducted in 2003 (Townsend et al., 2003). From the Florida landfill leachate survey, 32
of the 41 leachate samples were selected to reflect landfills that received MSW. Landfill
leachate data from Ehrig (1988) consolidate several landfill leachate studies from the
1970s.
Figure 5-1 presents the lead concentration data in µg/L on a log scale for several
landfill leachate and lysimeter studies. Complete data sets, from the US Leach 2000
database and the 2003 Florida landfill leachate survey, are presented as box-and-whisker
plots where the dashed line indicates the mean and the solid line the median. The edges
of the box are the 25% and 75% percentiles, the whiskers are the 10% and 90%
percentiles, and the dots are outliers. Data from Ehrig (1988) are summarized by the
minimum, maximum, and mean. For lysimeter data from Kemper et al. (1984) and the
control and E-waste lysimeters for this study, the weighted average lead concentration is
presented. For the excavated waste lysimeter, the acidic phase and methanogenic
weighted average lead concentrations are presented separately. The TC limit for lead is a
60
dotted line at 5 mg Pb/L, and the drinking water action limit is a dot-dash line at 15 µg
Pb/L.
FL UFStudy2004
Pb C
once
ntra
tion,
ug/
L
1
10
100
1000
10000
Drinking Water LimitTC Limit
1970sLandfills
Ehrig1988
USLeach2000
FLLeach2000
1980sLysimeters
Kemper1984
ExcavatedWaste
Lysimeter
E-wasteLysimeter
ControlLysimeter
max
mean
min
Figure 5-1. Lead concentrations from historic landfill leachate and lysimeter studies
compared to the current study
The landfill studies show a clear trend of decreasing lead concentrations over time.
In fact, the average lead concentration reported by Townsend et al. (2003) was lower than
the minimum reported by Ehrig (1988). The lysimeter study showed a similar trend. The
weighted average lead concentrations from Kemper et al. (1984) were much higher than
the concentrations in the current study. The excavated waste lysimeter weighted average
lead concentration was an order of magnitude higher in the acidic phase than the
methanogenic phase. The control and E-waste lysimeters were in the acid phase the
entire study, and the weighted average lead concentrations were about two orders of
61
magnitude less than those in Kemper et al. (1984). This diagram illustrates that the
amount that E-waste increased the leaching of lead is insignificant compared to the
decrease in landfill leachate lead concentrations during the last 20 or 30 years. The TC
limit for lead was exceeded only by one data point in the Leach 2000 database. The
drinking water action limit for lead was exceeded by the weighted average control and
E-waste lysimeters as well as the acidic phase excavated waste leachate.
One possible reason less lead leached from these lysimeters than historical studies
is that the amount and forms of lead in waste and the environment have changed. The
total concentration of lead in the simulated waste was 3.5 mg Pb/kg waste. This is much
lower than found in the late 1970s and 1980s, when lead was found to range from 300 to
1,628 mg Pb/kg waste (Ehrig, 1988). The fraction of the lead that is inorganic versus part
of an organic compound could have a large impact on leachability and the historic
decrease in lead concentrations in leachate.
This study has implications for the disposal of E-waste and for the regulation of
hazardous waste in general. Based on these results, E-waste disposal in landfills may not
pose a great threat to groundwater. While a significant input of lead to landfills, E-waste
is not necessarily a significant contributor to lead leaching from landfills. Lead is
ubiquitous in the environment, and it is not possible to completely eliminate lead from
the waste stream. Because of this impossibility, it is necessary to determine the most
important pathways, that is, damaging pathways, of human exposure to lead and
distribute resources accordingly. The potential for humans to be exposed to lead from
E-waste disposed in landfills is limited, and other sources of lead exposure are likely
more dangerous. Other chemicals in landfill leachate are more likely to occur at levels
62
that are more dangerous and to be transported to points of exposure (Townsend et al.
2003; Christensen et al., 2001).
The regulatory implications are that revisions are needed for the intended level of
protection to be delivered. Currently, the EPA is conducting a multi-year review of the
TC regulations and many states are considering actions targeted at E-waste. The EPA
intended for the TC hazardous waste classification to identify “broad classes of wastes
which are clearly hazardous” (55 FR 11799). The EPA clarified this in 2001, stating, “In
identifying TC hazardous wastes as ‘‘clearly hazardous’’ the agency was identifying a
universe of wastes that the agency believed may pose high enough risk so as to always
require classification as hazardous” (66 FR 27282). This study shows that E-waste does
not meet the criteria of “clearly hazardous” in terms of the potential for lead to be leached
out of landfills under acid-phase conditions. Even under these very aggressive leaching
conditions, the concentrations of lead were elevated by a fraction of the total lead present
in the short term. Therefore, the regulation of E-waste as a TC hazardous waste requires
further study and may not be appropriate.
A common criticism of the TC hazardous waste regulations is that the TCLP does
not simulate the leaching conditions inside a landfill. A detailed discussion of the
potential shortcomings of the toxicity characteristic is presented in the “Hazardous Waste
Characteristics Scoping Study”, (USEPA OSW, 1996). The TCLP has been widely used
to predict landfill leachate concentrations despite EPA advice for it not to be used in that
manner. A question to consider is whether the TCLP needs be predictive of leachate
concentrations in order for the regulatory scheme to provide the intended level of
63
protection? The classification of TC hazardous waste relies on the interaction between
the TCLP and the TC limits.
The TC limits, as currently derived for metals are inadequately supported by
science. The TC limits were “back-calculated” by “multiplying chronic toxicity
reference levels by dilution/attenuation factors” (55 FR 11802). The dilution and
attenuation factor (DAF) for lead was set in 1980 at 100 (45 FR 33084). Originally, the
EPA proposed a DAF of 10 but instead chose a DAF of 100 because of a lack of
empirical data to support a DAF of 10 (55 FR 11800). This study indicates that the
attenuation occurring inside the landfill is significant. In the case of precipitation and
sorption reactions in reducing environments, the mechanisms controlling attenuation in
the aquifer should be similar. Calculating the actual dilution and attenuation that occurs
in aquifers, instead of assuming a DAF of 100, could result in a DAF several orders of
magnitude greater than 100. The EPA is open to this approach and has said that the DAF
of 100 could be adjusted “if future studies indicated that another DAF was more
appropriate” and expected to use newer fate and transport models to derive newer DAFs
for metals (55 FR 11813). The revision of the TCLP would cause more disruption that
the adjustment of the TC limits.
In conclusion, this study shows an instance where the TCLP is not predictive of
leachate concentrations or lead leachability. The current TC limit for lead is
overprotective and does not reflect current risk assessment and groundwater modeling
techniques. More research is needed to better understand the chemistry at work and to
provide a more realistic risk assessment for the landfill disposal of E-waste. The
determination of an updated DAF for lead is probably the first step in evaluating the
64
protectiveness of current regulations. Groundwater models should be updated and
verified using data from actual landfills. Additional information for modeling could be
obtained by additional research on the mobility of lead in waste and groundwater. Field
data from landfill leachates and groundwater monitoring wells is currently available.
Retardation factors for lead could be determined by leaching E-waste in acid-phase MSW
leachate, then passing the leachate through MSW lysimeters. To better understand the
sources of lead in leachate and to what extent E-waste is leaching lead, lead isotopes in
wastes and leachates could be characterized. The fate of lead in landfills can be
evaluated using sequential extraction techniques and speciation models. Using speciation
data, the future fate of lead in landfills could be modeled much more effectively. An
updated risk assessment for E-waste disposal in landfills would consider these advances
in the scientific understanding of lead leaching.
65
CHAPTER 6 SUMMARY AND CONCLUSIONS
Electronics waste (E-waste) consists of discarded electronic equipment, generally,
anything containing a circuit board or cathode ray tube. Some types of E-waste are
considered hazardous wastes in the United States. In many places, landfill disposal of
E-waste is restricted because of concerns that toxic compounds, especially lead, could
leach from the waste and result in risk to human health and the environment. The
regulatory test used to determine if a waste is hazardous because of the leaching of toxic
compounds is the Toxicity Characteristic Leaching Procedure (TCLP). The TCLP is
intended to simulate the leaching of a waste under acid-phase landfill conditions. One
criticism of the TCLP is that it is not predictive of the concentration of contaminants in
actual landfill leachate.
This study uses simulated landfills or lysimeters to determine how lead leaches as a
result of adding E-waste to lysimeters filled with simulated municipal solid waste
(MSW). Two lysimeters were built with only simulated waste (control lysimeters), three
with simulated waste plus about 6% E-waste (E-waste lysimeters), and one lysimeter was
filled with waste excavated from a landfill (excavated waste). The lysimeters were
placed in holes excavated in an operating MSW landfill in Florida. Water was added
regularly and the water percolating through the waste, called leachate, was collected for
about one year.
The leachate from the control and E-waste lysimeters were typical of acid-phase
leachate throughout the study. The excavated waste lysimeter was in the acid phase
66
briefly and was fully methanogenic after 150 days. The highest concentrations of lead
occurred in the excavated waste lysimeter during the acid phase and decreased to below
detection limit in the methanogenic phase. The concentrations of lead from the control
and E-waste lysimeters were statistically different at the α = 0.05 level of significance
according to ANOVA analysis. The total mass of lead leached from the E-waste
lysimeters was greater than from the control lysimeters. However, the increase in the
mass of lead leached from the E-waste lysimeters was less than 0.018% of the total mass
of lead in the E-waste lysimeters.
Specific findings of this research:
• The concentrations of lead from the control and E-waste lysimeters were statistically different. The total mass of lead leached from the E-waste lysimeters was on average 22% greater than from the control lysimeters. However, the increase in the mass of lead leached from the E-waste lysimeters was less than 0.018% of the total mass of lead in the E-waste lysimeters.
• The amount of lead leached from the E-waste lysimeters was much lower than previous lysimeter studies. Landfill leachate lead concentrations are decreasing over time as well. The amount that the lead concentration was increased by the E-waste was insignificant compared to the decline of lead concentrations in leachate from eliminating lead from the waste stream.
• The current regulatory approach for toxicity characteristic hazardous wastes has shortcomings. The TCLP was not predictive of leachate concentrations or the lead available for leaching. The TC limits are most likely overprotective for lead.
• Future regulations should consider the role of lead mobility and transport by deriving an updated dilution and attenuation factor for lead. The revision of the TCLP would cause more disruption that the adjustment of the TC limits. No quick batch leaching test will be predictive for all wastes.
Policy makers may be misallocating limited public health and environmental
protection resources if the TC hazardous waste regulations are not as protective as
intended. Ultimately, better risk assessments will lead to more effective and efficient
spending of resources to reduce the potential for lead exposure. Perhaps future research
67
should focus on the remaining uncertainties in groundwater modeling and understanding
the chemistry and long-term consequences of E-waste disposal in landfills.
68
APPENDIX A PROJECT PHOTOGRAPHS
To join the pipes, a 3.5 inch diameter hole was drilled about two inches from the
bottom of the larger pipe (Figure F1). To keep the material in the large pipe, a
rectangular piece of triplanar HPDE geonet was extrusion welded to cover the hole
(Figure F1). The leachate collection pipe was butt welded to a 3.5 inch diameter 90-
degree HDPE elbow. The elbow was then welded to the hole in the larger pipe. The
bottom of the larger pipe was then butt welded to a one-inch thick HDPE plate. The
leachate collection pipe was “tacked” to the side of the larger pipe every two or three feet
by extrusion welding a “bead” on either side of the two pipes for about six inches. The
top of the leachate collection pipe was threaded to accept a NPT male plug. The top of
the larger pipe was left unfinished and a lid was made from a disk of one-inch thick
HDPE, the same diameter as the outside of the lysimeter. The lid was then turned on a
lathe to cut a groove into the edge of the lid, forming a “lip” or plug which fit the inside
diameter of the lysimeter.
Figure A-1. Lysimeter during construction
69
Figure A-2. Detail of welding triplanar geonet
Figure A-3. Outside view of geonet covering hole
70
Figure A-4. Elbow used to connect lysimeter to leachate collection pipe.
Figure A-5 Bucket auger
71
Figure A-6. Lowering lysimeter into landfill
Figure A-7. Backfilling around lysimeter with sand
72
Figure A-8. Water distribution system irrigation tubing
Figure A-9. Adding water to lysimeter
73
Figure A-10. Material used for simulated waste
Figure A-11. Mixing simulated waste
74
Figure A-12. Adding water to simulated waste
Figure A-13. Disassembled CRT monitor
75
Figure A-14. Central processing unit in lysimeter
Figure A-15. Monitor in lysimeter
76
Figure A-16 Smoke detectors in lysimeter
Figure A-17. Cell phones and rechargeable batteries in lysimeter
77
Figure A-18.Waste compactor
Figure A-19. Silicone caulk used to seal lysimeter.
78
APPENDIX B ADDITIONAL LEACHATE GRAPHS
Days Since Water Addition
0 100 200 300 400 500
Wat
er A
dded
- Le
acha
te C
olle
cted
(L)
0
50
100
150
200
250
300
350Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-1. Lysimeter water balance
Days Since Water Addition
0 100 200 300 400 500
Liqu
id to
Sol
id R
atio
(L:S
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-2 Liquid to solid ratio
79
Days Since Water Addition
0 50 100 150 200 250 300 350 400 450
Tota
l VFA
s (m
g/L)
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-3. Total volatile fatty acids vs. time
Days Since Water Addition
0 50 100 150 200 250 300 350 400 450
BO
D (m
g/L)
0
50000
100000
150000
200000
250000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-4. Biochemical oxygen demand vs. time
80
Days Since Water Addition0 50 100 150 200 250 300 350 400 450
Con
duct
ivity
(mS/
cm)
0
10
20
30
40
50
Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-4. Conductivity vs. time
Days Since Water Addition0 50 100 150 200 250 300 350 400 450
TD
S (m
g/L
)
0
10000
20000
30000
40000
50000
60000
70000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-5. Total dissolved solids vs. time
81
Days Since Water Addition
0 50 100 150 200 250 300 350 400 450
Leac
hate
Alk
alin
ity (m
g C
aCO
3/L)
0
5000
10000
15000
20000
25000Excavated WasteMSW Control 1MSW Control 2 MSW E-waste 1MSW E-waste 2MSW E-waste 3
Figure B-6. Alkalinity vs. time
Days since Placement0 50 100 150 200 250 300 350 400 450
Inch
es o
f Set
tlem
ent
0
5
10
15
20
25
30
35
Figure B-7. Settlement vs. time
82
APPENDIX C ADDITIONAL DATA
Table C-1. Detailed composition of E-waste components Computer E-waste 1 E-waste 2 E-waste 3 Lab Total Mass (grams) scale 9424.7 g 9550.0 g 9247.0 g 9001.3 gTotal (sum) grams 9310.9 9399.6 9187.3 8907.6Plastic Case (g) 2051.3 2079.2 2105.1 2068.7Metal case (g) 3862 3827.8 3626.1 3649 Circuit Boards (g) 1189.9 1201.6 1158.2 872.8 Power Supply (g) 1186.1 1189.4 1176.4 1198.3Disk Drives (g) 796.6 878 887.8 886.3 Fan (g) 225 223.6 233.7 232.5 Keyboard # E-waste 1 E-waste 2 E-waste 3 Lab Total weight (grams) scale 1117.3 1172.4 1177 1166.1 PWB (g) 16.9 20.6 20.5 17 Wires (g) 69.8 77.4 76 67 Ferrous Metal (g) 293.6 383.7 383.5 337.9 Plastic (Inside) (g) 181.3 157.2 169.7 164.2 Screen (plastic) (g) 23.5 11.4 11.6 23 Plastic Cover (g) 533.6 525.4 526.4 566 Actual Total (sum) (g) 1118.7 1175.7 1187.7 1175.1 Mouse # E-waste 1 E-waste 2 E-waste 3 Lab grams 136.4 136.4 136.4 136.4
Monitor # E-waste 1 E-waste 2 E-waste 3Wires (g) 0.41 0.36 0.36 Ferrous metal (g) 0.95 0.95 0.95 Nonferrous metal (g) 0.05 0.05 0.05 Plastic (g) 3.14 3.14 3.09 CRT (g) 6.91 7.09 7.14 total (g) 5.72 5.76 5.79 Cell Phones E-waste 1 E-waste 2 E-waste 3 i390 135.1 136.2 136.3 i1000 plus 106.3 105.9 105.6 I 1000 plus 106.6 105.8 107.9 i500 126.7 128.6 125.4 Total (grams) 474.7 476.5 475.2
Sum of 7 Ni-Cd cell phone batteries (g) 1059.5 1067.9 1061.9 Sum of 3 smoke detectors (g) 0.59 0.59 0.59
83
Table C-2. Leachate lead concentrations Lead mg/L
Sampling date Excavated waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 49/16/2004 0.02434 0.03843 0.02365 0.01151 0.0162710/7/2004 0.06013 0.03447 0.03696 0.04016 0.01908 0.02199
10/19/2004 0.10992 0.03385 0.03961 0.04954 0.02972 0.0250210/26/2004 0.14004 0.03447 0.04368 0.0447 0.03402 0.03483
11/4/2004 0.13035 0.03436 0.03893 0.05442 0.03623 0.037111/9/2004 0.15883 0.01142 0.04402 0.05379 0.0392 0.03478
11/16/2004 0.13783 0.04036 0.04127 0.05337 0.04705 0.042412/2/2004 0.05093 0.04263 0.04051 0.05553 0.05652 0.0479412/9/2004 0.002 0.03521 0.04059 0.04632 0.058 0.04994
12/15/2004 0.01358 0.03718 0.03876 0.03786 0.05326 0.0430112/22/2004 0.01599 0.03603 0.03317 0.04134 0.05234 0.04792
1/11/2005 0.0209 0.05348 0.04445 0.04467 0.05402 0.063841/18/2005 0.01964 0.05006 0.0379 0.04095 0.05454 0.052742/1/2005 0.01052 0.03595 0.03863 0.04464 0.05578 0.05406
2/15/2005 0.0112 0.03794 0.01894 0.04481 0.03829 0.06593/10/2005 0.00666 0.02713 0.01522 0.03689 0.03761 0.04913/22/2005 0.00536 0.0335 0.01055 0.02544 0.03722 0.045754/5/2005 0.00447 0.0245 0.01479 0.01671 0.01831 0.05739
4/19/2005 0.002 0.01355 0.002 0.02957 0.00664 0.040955/3/2005 0.00713 0.00818 0.01403 0.01332 0.02187 0.02919
5/25/2005 0.002 0.002 0.01869 0.01423 0.01915 0.028666/8/2005 0.002 0.002 0.01596 0.02276 0.01874 0.029057/7/2005 0.002 0.0178 0.01782 0.01441 0.02593 0.02973
7/28/2005 0.01686 0.01552 8/3/2005 0.00612 0.00717 0.03745 0.02628 0.02831
Table C-3. Leachate lead descriptive statistics Lead Descriptive Statistics
Excavated waste
Control 1 Control 2 E-waste 1
E-waste 2
E-waste 4
Mean 0.0415 0.0277 0.0283 0.0369 0.0355 0.0407Standard Error 0.0117 0.00289 0.00276 0.00279 0.00323 0.0027Median 0.0124 0.0339 0.037 0.0406 0.0367 0.0417Standard Deviation 0.0547 0.0145 0.0138 0.0137 0.0158 0.0132Sample Variance 0.00299 0.000209 0.000191 0.000187 0.00025 0.000175Kurtosis -0.1138 -0.7427 -1.51 -0.9915 -1.216 -0.7179Skewness 1.243 -0.3439 -0.3872 -0.4804 -0.07259 0.1311Range 0.157 0.0515 0.0425 0.0422 0.0514 0.0496Minimum 0.002 0.002 0.002 0.0133 0.00664 0.0163Maximum 0.159 0.0535 0.0445 0.0555 0.058 0.0659Count 22 25 25 24 24 24Confidence Level(95.0%) 0.0243 0.00597 0.0057 0.00577 0.00667 0.00559
84
Table C-4. Leachate pH pH
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/17/04 5.59 8/20/04 5.28 8/24/04 5.77 4.95 4.99 4.98 5.54 8/31/04 5.82 4.96 5.01 5.63 5.8
9/9/04 6.07 5.03 5.02 5.65 5.95 9/16/04 6.14 4.97 4.98 5.59 5.95 9/23/04 6.14 6 10/1/04 5.12 6.21 5.07 4.98 5.51 6 10/7/04 5.43 5.98 5 5.07 5.22 5.64
10/26/04 6.06 5.92 4.97 4.94 4.91 5.09 11/4/04 6.57 5.92 5.15 5.19 5.1 5.3 11/9/04 6.41 5.76 5.11 5.08 4.98 5.14
11/16/04 6.24 5.53 5.15 5.13 5.04 5.19 11/23/04 6.21 5.23 5.03 5.09 5.03 5.13
12/2/04 6.79 5.25 5.14 5.15 5.07 5.14 12/9/04 7.82 5.28 5.19 5.27 5.19 5.17
12/15/04 8.04 5.24 5.22 5.23 5.15 5.2 12/22/04 8.11 5.15 5.17 5.15 5.17 12/30/04 7.98 5.18 5.21 5.23 5.13 5.2
1/6/05 7.67 5.18 5.18 5.18 5.11 5.21 1/11/05 7.64 5.15 5.18 5.16 5.12 5.12 1/18/05 7.67 5.17 5.19 5.21 1/25/05 7.55 5.12 5.13 5.19 5.13 5.15
2/1/05 7.47 5.03 5.17 5.16 5.15 5.11 2/8/05 7.4 5.02 5.13 5.16 5.15 5.15
2/15/05 7.53 5.02 5.08 5.16 5.14 5.11 2/24/05 7.4 5.07 5.13 5.19 5.17 5.11
3/4/05 7.51 5.04 5.09 5.21 5.14 5.12 3/10/05 7.48 5.06 5.11 5.22 5.18 5.16 3/18/05 7.34 5.01 5.09 5.17 5.14 5.13 3/22/05 7.36 4.95 5.01 5.06 5.06 5.06 3/29/05 7.34 4.96 5.07 5.14 5.13 5.11
4/5/05 7.33 4.86 4.98 5.07 5.04 5.1 4/12/05 7.25 4.94 5.15 5.26 5.14 5.14 4/19/05 7.26 4.92 5.17 5.24 5.13 5.16 4/26/05 7.18 4.85 5.09 5.15 5.04 5.08
5/3/05 7.16 4.92 5 5.15 5.08 5.08 5/11/05 7.24 4.92 5.14 5.22 5.19 5.16 5/16/05 7.15 4.94 5.18 5.21 5.15 5.13 5/20/05 7.28 4.99 5.13 5.23 5.14 5.16 5/25/05 7.22 4.9 5.08 5.16 5.12 5.15
6/2/05 4.94 5.14 5.17 5.08 5.11 6/8/05 7.22 4.92 5.15 5.26 5.12 5.26
6/14/05 7.22 4.96 5.16 5.26 5.15 5.27 6/22/05 5.17 5.18
7/7/05 7.26 5.16 5.21 5.24 5.17 5.23
85
Table C-4. continued pH
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
7/26/05 5.08 8/3/05 4.95 5.22 5.21 5.15 5.22
8/10/05 4.82 5.18 5.13 5.21 8/17/05 4.91 5.28 5.7 5.2 5.2 8/18/05 5.18 8/23/05 7.2 4.82 5.09 5.55 5.25 5.2
9/1/05 7.13 4.83 5.11 5.33 4.98 5.18 9/8/05 7.19 4.77 5.08 5.17 4.88 5.26
9/12/05 4.8 5.2 5.26 4.97 5.26 9/15/05 4.63 5.1 9/16/05 4.67 5.04 5.31 4.8 5.23 9/22/05 7.19 4.57 5.04 5.23 4.71 5.15 9/29/05 7.11 4.66 5.13 5.46 4.76 5.15
86
Table C-5. Leachate total volatile fatty acids Total VFAs
Sampling date Excavated Waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3 8/24/04 19900 25500 23100 17700 8/31/04 18200 29800 29600 17200 32400
9/9/04 22300 35100 31300 17800 321009/16/04 35400 34500 24300 462009/23/04 31400 4220010/1/04 30000 41500 32300 27300 4370010/7/04 26500 35600 38300 28200 29900 3920011/4/04 38800 32200 29600 27200 25000 37100
11/16/04 39900 32700 39100 33500 25800 2850012/2/04 35200 36200 29900 38300 3350012/9/04 10500 24200 32000 28300 30600 37000
12/15/04 680 31100 32100 27200 29800 379001/6/05 157 26900 39100 31500 37800 37300
1/18/05 143 28700 35400 24100 36500 345002/1/05 151 17300 26900 28700 31900 40600
3/10/05 272 13500 19700 21200 5350 208003/22/05 257 19400 15300 15000 8870 18000
4/5/05 0 13700 21500 24600 23000 364004/19/05 21.5 14100 15600 20900 11600 23200
5/3/05 116 6070 37000 12800 8970 11200 Table C-6. Leachate biochemical oxygen demand BOD
Sampling date Excavated Waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3 8/17/04 2300 8/24/04 17000 19000 14000 6800
9/9/04 >40800 >40800 >40800 30000 >40800 9/16/04 57000 170000 75000 54000 10/1/04 9600 69000 66000 87000 41000 72000
10/26/04 47000 50000 58000 75000 58000 6300012/9/04 20000 48000 63000 51000 69000 65000
1/6/05 1500 33000 37000 28000 39000 350002/1/05bdl 32000 40000 120000 140000 110000
3/10/05 330 11000 8000 9000 11000 170004/5/05 330 17000 21000 20000 17000 33000
4/19/05 240 140000 150000 190000 200000 2000005/3/05 75 2500 7000 3500 11000 6500
5/25/05 260 80000 92000 96000 99000 1000007/7/05 1800 77000 77000 46000 46000 47000
87
Table C-7. Leachate chemical oxygen demand COD
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/17/04 5200 8/24/04 96000 79000 79000 43000
9/9/04 64000 80000 84000 52000 56000 9/16/04 79000 83000 87000 54000 85000 9/23/04 77000 79000 10/1/04 25000 74000 86000 85000 61000 87000 10/7/04 37000 82000 98000 85000 69000
10/19/04 72000 87000 96000 88000 72000 96000 10/26/04 76000 82000 94000 87000 69000 62000
11/4/04 68000 81000 96000 79000 79000 97000 11/16/04 85000 71000 97000 74000 80000 70000
12/9/04 26000 75000 95000 95000 100000 110000 12/15/04 14000 80000 94000 91000 98000 110000
1/6/05 11000 70000 85000 82000 99000 110000 1/18/05 9000 45000 76000 65000 68000 61000
2/1/05 8400 51000 74000 62000 80000 92000 2/8/05 7000 54000 62000 52000 64000 77000
2/15/05 5100 56000 57000 55000 65000 74000 2/24/05 6700 49000 49000 55000 53000 57000 3/10/05 5800 36000 33000 43000 45000 58000 3/18/05 38000 45000 57000 3/22/05 4700 31000 30000 34000 42000 57000 3/29/05 4900 23000 30000 30000 38000 55000
4/5/05 3700 26000 26000 22000 28000 50000 4/12/05 3300 24000 20000 20000 26000 49000 4/19/05 2800 19000 17000 22000 22000 41000 4/26/05 2800 15000 16000 20000 19000 34000
5/3/05 2500 14000 17000 15000 19000 25000 5/11/05 2300 11000 14000 14000 17000 5/16/05 14000 14000 5/20/05 2200 11000 13000 12000 17000 20000 5/25/05 2000 10000 13000 14000 15000 18000
6/2/05 11000 12000 10000 16000 17000 6/8/05 2000 11000 12000 11000 14000 10000
6/14/05 11000 11000 9000 13000 11000 7/7/05 2200 12000 11000 9600 13000 14000 8/3/05 13000 11000 10000 13000 14000
8/10/05 12000 11000 9600 11000 13000 8/23/05 2100 11000 11000 8600 11000 11000
9/1/05 2000 11000 12000 11000 12000 13000 9/8/05 1900 12000 14000 12000 13000 11000
9/15/05 11000 14000 9/16/05 11000 14000 11000 12000 13000 9/22/05 1600 11000 15000 12000 12000 14000 9/29/05 1400 10000 15000 12000 11000 12000
88
Table C-8. Leachate total organic carbon TOC
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
9/9/04 27000 33000 32000 18000 27000 9/30/04 9200 28000 34000 31000 20000 29000 11/4/04 31000 24000 33000 33000 29000 31000 12/9/04 7400 24000 29000 28000 31000 36000
1/6/05 2800 22000 27000 25000 28000 31000 1/18/05 2700 21000 23000 22000 29000 32000
2/1/05 2400 15000 23000 18000 23000 26000 2/15/05 1700 17000 16000 17000 19000 20000 3/10/05 1600 12000 10000 15000 14000 18000 3/22/05 1500 10000 8900 11000 13000 20000
4/5/05 990 7600 14000 6600 7800 15000 4/19/05 710 5700 5100 5700 6500 12000
5/3/05 610 4100 5300 4400 5500 7700 5/11/05 600 3200 4100 4000 4900 7200 5/25/05 570 3000 3700 3600 4300 4800
6/2/05 3000 3700 3300 4300 4900 6/8/05 590 3100 3500 2900 3900 3000 7/7/05 560 3500 2900 2600 4000 4100
8/23/05 680 3600 3500 2600 3400 3300
89
Table C-9 Leachate oxidation reduction potential ORP
Excavated Waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/24/04 9/9/04
9/16/04 9/23/04 11/4/04 11/9/04
11/16/04 11/23/04
12/2/04 12/9/04 -152 116 95 98 67 130
12/15/04 -136 145 122 172 92 11312/30/04 -124 103 93 112 92 73
1/6/05 -127 82 92 77 79 631/11/05 -142 114 76 51 1101/18/05 -105 151 107 99 85 1061/25/05 -115 132 78 55 52
2/1/05 -89 149 78 138 88 792/8/05 -60 156 140 101 125 106
2/15/05 16 154 169 98 90 1242/24/05 -86 126 85 108 78
3/4/05 -81 165 129 88 157 1423/10/05 -82 184 151 137 196 1353/18/05 -66 158 159 49 60 743/22/05 -74 176 175 131 114 743/29/05 -19 182 150 139 145 66
4/5/05 -70 192 186 119 184 1144/12/05 -51 237 180 147 183 1224/19/05 -7 188 174 154 181 1084/26/05 -20 241 182 190 208 124
5/3/05 43 235 195 176 190 1475/11/05 -12 259 147 81 142 -85/16/05 -7 245 149 52 143 845/20/05 -20 184 167 141 131 455/25/05 -31 229 129 30 29 33
6/2/05 218 126 112 127 586/8/05 -15 215 121 -4 18 -1
6/14/05 -44 231 159 139 144 1166/22/05 139 139
7/7/05 2 160 124 18 28 1027/26/05 239
8/3/05 253 180 157 154 1408/17/05 248 8/23/05 231 166 32 166 136
9/8/05 9 236 141 151 172 162
90
Table C-10. Leachate conductivity Conductivity Sampling date Excavated
Waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/20/04 11.2 8/24/04 18.8 16.6 7.2 12.7 17.1 8/31/04 19.8 19 23 15.1 13.4
9/9/04 26 25.8 17.8 15.5 26.8 9/16/04 28 26.4 25.2 20.8 32.8 10/1/04 10.6 29.8 25.6 27.2 18.6 32.6 10/7/04 18.4 28 25.4 26 23 32
10/19/04 24.2 28.2 28 27 23.6 29 11/4/04 32.3 30.9 28.1 27.9 26.7 25.6 11/9/04 40 25.5 26.8 26.7 23.9 27
11/16/04 47.4 29.5 28.8 28.9 27.8 32 11/23/04 46 30.9 31.2 29.3 28 30.8
12/2/04 44 25.3 26.3 26.3 27.2 30.3 12/15/04 30.6 19.8 22.3 24.2 32.3 23.5 12/22/04 26.3 27.6 15.7 32.1 34.3 16.6 12/30/04 26.7 29.6 31.8 33.7 39.2
1/11/05 24.5 19.9 19.9 19.1 22.6 24.2 2/1/05 23.5 15.3 21.8 17.1 23.6 26.4 2/8/05 23.4 15.1 17 16.3 19.3 22.8
2/15/05 21.9 15.3 15.3 15.7 17.7 21.1 2/24/05 18.8 14.4 13.9 15.4 16.9 17.5
3/4/05 21.1 11.9 11.2 13.9 14.3 19.6 3/10/05 18.7 11.3 10.8 13.5 12.9 14.1 3/22/05 16.1 10 9.44 10.9 12.7 14.5
4/5/05 13.3 7.72 7.63 7.5 8.4 14.1 5/20/05 9.55 3.69 3.09 5.08 5.7 6.31 5/25/05 3.55 4.85 4.73 5.24 6.02
7/7/05 9.25 4.41 4.23 3.67 4.58 5.03 7/26/05 4.72
8/3/05 4.44 4.83 8/23/05 3.96 4.73 4.38 4.46 4.98
91
Table C-11. Leachate total dissolved solids TDS
Sampling date Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/24/04 50100 44500 50400 24200 9/9/04 52900 6590 64000 30800 43300
9/16/04 46400 57800 57400 28200 46000 9/23/04 48600 50000 10/1/04 14200 46100 62200 59600 32500 51000 10/7/04 22600 45600 59500 57800 38000 52800
10/19/04 51900 44800 61300 60600 48000 58700 10/26/04 64000 41900 57500 57200 51000 64500
11/4/04 59700 41700 57700 56200 52200 59600 11/16/04 57000 43800 56600 54900 53200 61700
12/2/04 32300 44900 47800 45700 52400 57700 12/15/04 13900 38800 41700 38900 50100 55100
1/6/05 12700 37100 38100 37200 48400 51400 1/18/05 15500 35100 32400 30400 43500 48800 1/25/05 11900 24600 32000 25500 33800 39300 2/15/05 10800 29400 21800 22300 24600 27400 3/10/05 14300 19100 13400 17600 17300 22700 3/22/05 8600 15400 11700 12400 15300 21300
4/5/05 6500 11700 9400 7800 9100 20600 4/19/05 5300 6900 7000 7400 7400 14500
5/3/05 4590 4770 5980 4970 5960 7600 5/25/05 4530 3620 4740 4520 5360 5180
6/8/05 3290 2860 3530 3250 3790 2630 7/7/05 4600 4130 4370 3340 4420 4090 8/3/05 4060 4760 3480 3650 3810
8/23/05 4500 4270 5500 4360 5920 4100 9/8/05 3370 4600 7030 5750 3270
9/22/05 3280 4020 7080 5920 4960 4450 9/29/05 2700 3560 7390 6080 4470 4320
92
Table C-12. Leachate alkalinity Alkalinity
Excavated Waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/17/04 1000 8/24/04 11900 5900 4700 2800 8/31/04 10900 5300 4400 6800 10300
9/9/04 16000 10100 9700 9600 169009/16/04 18400 10600 9500 10600 1990010/1/04 3900 17200 9900 9100 11000 1860010/7/04 8500 17700 11300 10700 10400 18200
10/19/04 12400 17000 10000 10100 9300 1500010/26/04 13700 16200 8700 9000 8300 13400
11/4/04 17500 14900 7000 8100 5700 1190011/16/04 11100 14200 7100 9300 8000 13000
12/2/04 16400 10000 8800 8700 8300 1250012/15/04 14000 9000 7500 6400 7200 11200
1/6/05 13500 8600 9200 7200 7300 106001/18/05 13300 9200 9000 7800 7300 10300
2/1/05 13000 9200 9300 8000 7000 102002/15/05 10100 6300 5300 5700 6400 75003/10/05 5500 3100 3300 3400 45003/22/05 5800 3100 3300 4000 5000 6500
4/5/05 4500 2000 2400 4400 2700 52004/19/05 7500 1850 2250 3800 2500 5100
5/3/05 4000 900 1600 1600 1800 21005/16/05 1750 1750 5/25/05 4100 800 1500 2200 2200 2500
93
Table C-13 Leachate chloride Cl- mg/L
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
9/7/2004 495 166 98 9039/16/2004 891 831 759 567 7279/30/2004 846 852 800 772 590 91110/7/2004 875 879 873 828 690 963
10/26/2004 2225 575 738 893 998 114411/6/2004 2200 642 716 687 914 1009
11/16/2004 2268 853 922 976 925 114412/2/2004 2192 800 858 870 983 1137
12/15/2004 1583 443 375 411 476 5231/5/2005 2200 800 526 683 870 934
1/18/2005 2274 576 557 755 9912/1/2005 1687 411 558 477 660 863
2/15/2005 1596 746 384 468 470 4513/10/2005 1580 503 271 350 357 3963/22/2005 1311 406 235 302 358 3724/5/2005 1775 939 554 500 515 932
4/20/2005 1517 649 359 422 448 6985/5/2005 967 281 483 331 397 491
5/25/2005 852 346 397 382 446 4916/8/2005 875 461 483 331 397 4917/7/2005 836 249 255 211 251 267
Table C-13. Leachate sulfides Sulfides
Excavated Waste Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
8/24/04 0.51 0.12 0.12 0.23 8/31/04 0.53 0.09 0.16 1.1 5.4 9/16/04 0.63 0.3 0.12 0.2 1.6 9/23/04 0.5 1.2 10/1/04 0.03 0.3 0.08 0.11 0.12 4.5 10/7/04 0.48 0.08 0.13 0.14 0.75
10/19/04 0.35 0.1 0.09 0.09 2.9 10/26/04 0.23 0.4 0.08 0.13 0.07 0.65 11/4/04 0.32 0.3 0.08 0.09 0.07 0.45
11/16/04 0.43 0.28 0.08 0.095 0.085 0.5 12/2/04 2.3 0.4 0.09 0.43 12/9/04 21 0.43 0.09 0.08 0.085
1/6/05 1.3 0.13 0.085 0.075 0.075 0.25 1/18/05 3.8 0.2 0.055 0.07 0.075 0.33
2/1/05 3.1 0.18 0.055 0.06 0.06 0.18 2/15/05 2 0.18 0.04 0.05 0.06 0.18 3/10/05 1.4 0.15 0.04 0.04 0.05 0.23 3/22/05 0.1 0.04 0.03 0.03 0.18
4/5/05 0.85 0.8 0.05 0.04 0.06 0.15
94
Table C-14. Volume of leachate collected Leachate Volume (L)
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
7/12/04 0 0 0 0 0 0 7/26/04 0 0 0 0 0 0
8/7/04 0 0 0 0 0 0 8/17/04 0 0 0 0 27.1 0 8/20/04 0 0 0 0 65.9 0 8/24/04 0 14.6 10.5 11.2 83.2 2.1 8/26/04 0 14.6 10.5 11.2 83.2 4.1 8/31/04 0 25.8 23.6 24.3 96.3 10
9/9/04 0 36 38.7 37.5 103 21.3 9/16/04 0 41.7 46.7 43.2 110 34.6 9/23/04 0 52.6 46.7 43.2 110 38 10/1/04 2.5 58.4 58.2 53.7 116 44 10/7/04 3.9 74.1 66.7 61.8 129 56.2
10/19/04 5.7 84.2 83.5 77.2 144 63.9 10/26/04 11.8 93.2 90.5 82.9 154 74.9
11/4/04 15.4 105 98 95.5 165 85.1 11/9/04 20.2 112 103 101 171 91.9
11/16/04 24.5 121 111 110 180 101 11/23/04 33.5 141 126 132 196 112
12/2/04 39.9 154 139 144 207 121 12/9/04 47.7 165 151 159 220 133
12/15/04 53.4 173 159 166 229 140 12/22/04 56.7 181 167 173 236 143 12/30/04 67.5 188 176 182 243 151
1/6/05 80.8 205 193 202 258 165 1/11/05 90.2 219 210 221 276 175 1/18/05 98.4 231 223 231 288 183 1/25/05 108 251 244 256 313 201
2/1/05 136 286 301 299 354 241 2/8/05 152 310 320 323 376 265
2/15/05 164 324 328 330 390 277 2/24/05 177 344 347 345 413 289
3/4/05 190 363 367 370 423 304 3/10/05 194 383 383 385 438 308 3/18/05 217 408 414 418 464 316 3/22/05 231 427 428 437 481 322 3/24/05 231 430 431 439 485 324 3/29/05 256 457 465 475 512 331
4/2/05 256 484 486 508 541 350 4/5/05 279 509 502 532 557 354 4/9/05 279 531 513 541 566 363
4/12/05 297 535 516 544 568 370 4/17/05 297 559 524 555 586 392 4/19/05 321 582 529 559 591 408 4/24/05 342 607 550 569 611 430 4/26/05 356 630 557 575 618 444
95
Table C-14. continued Leachate Volume (L)
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
5/1/05 373 650 583 605 640 467 5/3/05 387 667 602 618 654 484 5/8/05 395 672 624 641 654 491
5/11/05 404 678 636 653 663 497 5/16/05 415 683 644 660 668 504 5/20/05 423 706 664 676 686 528 5/25/05 432 718 691 706 699 543
6/2/05 432 740 724 727 727 566 6/8/05 447 755 742 753 744 582
6/14/05 455 766 765 777 756 587 6/22/05 455 766 794 807 756 587
7/7/05 473 789 813 822 779 602 7/13/05 473 789 813 822 779 602 7/26/05 473 789 826 822 779 602 7/28/05 473 805 826 822 779 602
8/3/05 473 810 832 827 796 608 8/10/05 473 810 832 827 797 613 8/17/05 473 815 837 831 797 613 8/18/05 473 815 837 831 797 613 8/23/05 489 822 845 836 801 617
9/1/05 526 838 860 850 812 620 9/8/05 547 846 872 862 818 622
9/12/05 547 852 877 867 823 623 9/15/05 547 874 888 867 823 623 9/16/05 547 875 901 886 840 631 9/22/05 577 898 922 914 861 662 9/29/05 601 898 922 947 901 692
96
Table C-15. Volume of water added Volume of Water Added (L)
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
7/12/04 23 36 36 37 36 36 7/26/04 59 72 72 73 72 72
8/7/04 95 108 108 109 108 108 8/17/04 132 144 146 147 145 146 8/20/04 132 144 146 147 145 146 8/24/04 132 144 146 147 145 146 8/26/04 167 163 163 165 145 164 8/31/04 167 163 163 165 145 164
9/9/04 167 163 163 165 145 164 9/16/04 167 163 163 165 145 164 9/23/04 181 185 184 183 166 182 10/1/04 196 208 203 199 190 206 10/7/04 196 208 203 199 190 206
10/19/04 216 229 216 219 211 223 10/26/04 216 229 216 219 211 223
11/4/04 236 248 233 236 227 237 11/9/04 236 248 233 236 227 237
11/16/04 260 277 258 267 251 257 11/23/04 260 277 258 267 251 257
12/2/04 280 299 282 291 275 280 12/9/04 280 299 282 291 275 280
12/15/04 280 299 282 291 275 280 12/22/04 298 320 303 311 295 299 12/30/04 319 342 325 337 315 316
1/6/05 319 359 347 356 337 329 1/11/05 319 359 347 356 337 329 1/18/05 341 388 377 389 374 353 1/25/05 403 454 445 456 440 420
2/1/05 403 454 445 456 440 420 2/8/05 403 454 445 456 440 420
2/15/05 403 487 479 491 473 451 2/24/05 403 507 500 511 473 451
3/4/05 420 535 522 528 499 451 3/10/05 463 572 556 567 537 451 3/18/05 463 572 556 567 537 451 3/22/05 463 572 556 567 537 451 3/24/05 528 638 617 630 537 484 3/29/05 541 678 651 672 577 519
4/2/05 541 678 651 672 577 519 4/5/05 541 678 651 672 577 519 4/9/05 541 678 651 672 577 519
4/12/05 589 736 673 697 610 577 4/17/05 589 736 673 697 610 577 4/19/05 614 785 704 726 638 614 4/24/05 614 785 704 726 638 614 4/26/05 624 821 751 770 675 656
97
Table C-15. continued Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
5/1/05 624 821 751 770 675 656 5/3/05 624 821 785 805 675 656 5/8/05 624 821 785 805 675 656
5/11/05 644 839 785 805 689 675 5/16/05 654 870 823 836 720 710 5/20/05 654 870 854 869 720 710 5/25/05 664 896 890 903 761 744
6/2/05 664 896 890 903 761 744 6/8/05 672 917 925 938 784 771
6/14/05 684 934 958 969 798 771 6/22/05 684 934 958 969 798 771
7/7/05 684 934 971 969 798 771 7/13/05 684 934 971 969 798 771 7/26/05 684 934 971 969 798 771 7/28/05 684 961 971 969 798 771
8/3/05 684 961 971 969 798 771 8/10/05 684 964 971 969 798 771 8/17/05 684 964 971 969 798 771 8/18/05 684 987 994 993 824 771 8/23/05 702 995 1002 1001 832 779
9/1/05 702 1007 1017 1016 847 794 9/8/05 737 1017 1027 1026 857 804
9/12/05 737 1057 1055 1060 889 834 9/15/05 737 1084 1081 1084 914 860 9/16/05 737 1084 1081 1084 914 860 9/22/05 772 1124 1123 1127 954 901 9/29/05 772 1124 1123 1127 954 901
98
Table C-16. Water balance Water balance (L)
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
7/12/04 23 36 36 37 36 36 7/26/04 59 72 72 73 72 72
8/7/04 95 108 108 109 108 108 8/17/04 132 144 146 147 118 146 8/20/04 132 144 146 147 79 146 8/24/04 132 130 135 135 62 144 8/26/04 167 148 152 154 62 160 8/31/04 167 137 139 140 49 154
9/9/04 167 127 124 127 42 143 9/16/04 167 121 116 122 35 130 9/23/04 181 133 138 140 56 144 10/1/04 194 150 145 145 75 162 10/7/04 192 134 137 137 62 150
10/19/04 211 145 133 141 67 160 10/26/04 205 136 126 136 57 149
11/4/04 220 143 135 140 62 152 11/9/04 216 136 130 135 56 145
11/16/04 236 155 147 156 71 156 11/23/04 227 136 132 134 56 146
12/2/04 241 145 143 147 68 159 12/9/04 233 134 131 132 55 147
12/15/04 227 126 122 125 46 140 12/22/04 241 139 135 139 59 156 12/30/04 251 154 149 156 72 164
1/6/05 238 154 154 154 79 163 1/11/05 228 141 137 135 61 154 1/18/05 243 157 154 158 86 170 1/25/05 295 204 201 200 127 219
2/1/05 267 169 144 157 86 179 2/8/05 251 145 125 132 63 155
2/15/05 239 164 152 161 83 174 2/24/05 226 163 153 166 60 163
3/4/05 231 172 155 158 76 147 3/10/05 269 189 173 182 99 144 3/18/05 246 164 142 149 73 136 3/22/05 233 144 128 130 55 130 3/24/05 297 207 186 191 52 160 3/29/05 285 221 186 197 64 188
4/2/05 285 194 165 164 35 169 4/5/05 263 169 149 141 20 165 4/9/05 263 147 138 131 11 156
4/12/05 292 201 157 153 42 207 4/17/05 292 177 149 141 24 185 4/19/05 293 202 176 166 47 205 4/24/05 272 178 154 156 27 184
99
Table C-16. continued Water balance (L)
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
4/26/05 268 191 195 195 57 212 5/1/05 251 171 168 165 34 189 5/3/05 238 153 182 186 21 172 5/8/05 229 148 161 164 21 165
5/11/05 239 161 149 152 26 178 5/16/05 239 187 179 176 52 206 5/20/05 230 164 190 193 35 182 5/25/05 232 178 198 197 61 201
6/2/05 232 155 165 176 34 178 6/8/05 225 162 183 186 40 189
6/14/05 230 168 193 192 42 184 6/22/05 230 168 164 162 42 184
7/7/05 211 145 158 147 19 169 7/13/05 211 145 158 147 19 169 7/26/05 211 145 145 147 19 169 7/28/05 211 156 145 147 19 169
8/3/05 211 151 139 142 2 163 8/10/05 211 154 139 142 1 158 8/17/05 211 149 134 138 1 158 8/18/05 211 172 157 162 27 158 8/23/05 213 173 157 165 31 162
9/1/05 176 169 157 166 36 174 9/8/05 190 171 155 165 40 182
9/12/05 190 206 178 193 65 211 9/15/05 190 210 194 217 90 238 9/16/05 190 209 181 198 74 230 9/22/05 195 226 201 213 93 239 9/29/05 171 226 201 180 53 209
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Table C-17. Methane gas composition in lysimeter CH4
Excavated Waste
Control 1 Control 2 E-waste 1 E-waste 2 E-waste 3
11/16/04 57.2% 22.7% 27.1% 27.4% 12.7% 14.3% 1/6/05 58.0% 22.5% 29.0%
1/11/05 55.9% 24.3% 30.0% 34.7% 16.0% 17.0% 2/24/05 30.9% 35.9% 37.3% 10.1% 25.5%
3/4/05 35.6% 40.0% 40.6% 0.3% 25.5% 3/10/05 56.3% 35.4% 38.6% 39.2% 0.5% 24.0%
4/5/05 56.5% 41.7% 40.9% 42.8% 25.7% 23.0% 4/12/05 55.2% 42.3% 41.9% 44.0% 23.4% 26.6% 4/19/05 57.2% 44.4% 42.4% 44.9% 22.7% 28.0% 4/26/05 56.1% 44.6% 43.4% 42.8% 23.5% 30.0%
5/3/05 46.0% 45.7% 47.0% 33.2% 5/11/05 55.6% 45.4% 45.0% 42.5% 52.6% 51.6% 6/22/05 56.1% 49.5% 47.1% 49.0% 40.9% 40.3%
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Table C-18. T-test comparing control 1 and control 2 t-Test: Two-Sample Assuming Equal Variances alpha 0.05
Control 1 Control 2 Mean 0.028189 0.028837Variance 0.000213 0.000192Observations 24 24Pooled Variance 0.000202 Hypothesized Mean Difference 0 df 46 t Stat -0.15785 P(T<=t) one-tail 0.437632 t Critical one-tail 1.678659 P(T<=t) two-tail 0.875264 t Critical two-tail 2.012894
Table C-19. Single factor analysis of variance for E-waste lysimeters Anova: Single Factor alpha 0.05 SUMMARY Groups Count Sum Average Variance E-waste 1 24 0.88653 0.036939 0.000187 E-waste 2 24 0.85131 0.035471 0.00025 E-waste 3 24 0.97587 0.040661 0.000175 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 0.000344 2 0.000172 0.84245 0.435035 3.129642Within Groups 0.01407 69 0.000204 Total 0.014414 71
102
Table C-20. Two-factor analysis of variation for control 1, control 2, E-waste 1, and E-waste 2
Anova: Two-Factor With Replication alpha 0.05 SUMMARY Control E-waste Total
1 Count 24 24 48 Sum 0.67653 0.88653 1.56306 Average 0.028189 0.036939 0.032564 Variance 0.000213 0.000187 0.000215
2 Count 24 24 48 Sum 0.69208 0.85131 1.54339 Average 0.028837 0.035471 0.032154 Variance 0.000192 0.00025 0.000227
Total Count 48 48 Sum 1.36861 1.73784 Average 0.028513 0.036205 Variance 0.000198 0.000214 ANOVA
Source of Variation SS df MS F P-value F crit
Sample 4.03E-06 1 4.03E-06 0.019171 0.89018 3.944535Columns 0.00142 1 0.00142 6.755119 0.010888 3.944535Interaction 2.68E-05 1 2.68E-05 0.127718 0.721628 3.944535Within 0.019341 92 0.00021 Total 0.020792 95
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BIOGRAPHICAL SKETCH
Erik Spalvins was born in Knoxville, Tennessee in 1975. After getting a Bachelor
of Science degree from the University of Tennessee, Knoxville, he accepted a job with
the University of Florida / Institute of Food and Agricultural Science (IFAS) Cooperative
Extension Service. He started graduate school in 2003 and is happy to have worked on
many interesting and challenging projects.
