2107460 Introduction to Hazardous Waste

Treatment

Fate and Transport of Contaminants

Manaskorn Rachakornkij, Ph.D. NCE-EHWM

Department of Environmental Engineering Faculty of Engineering

CHULALONGKORN UNIVERSITY

2

3

Some fate and transport processes in

the subsurface and atmospheric

environment.

4

Some fate and transport

processes in the aquatic

environment.

5

Site Investigation

First step: site investigation

What chemicals are present?

How much of these chemicals were deposited at the site?

Where, on the site, are these chemicals located?

6

What Chemicals?

Historical records

What industrial activities occurred at the Site?

What chemicals were used at the Site?

Where were they used?

Were chemicals stored in tanks? Where? Are they still in the tanks?

7

Chemical Amounts?

Second step: How much of these chemicals were released?

Records?

Recollection of employees?

Similar industries?

8

Fates of Chemicals

Where do the chemicals go once they are released to the environment? Air

Soils

Groundwater

Surface water

Biota (plants or animals)

Sediments

9

To the Air

Liquid to gas phase (volatilization)

Chemicals that do not want to be in water (hydrophobic)

Chemicals that prefer to be in air (volatile organic chemicals - VOCs)

Chemicals that can move into air, but do so more slowly (semivolatile organic chemicals)

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To the Air

11

Particulates in Air

Very small fragments of material (particulates) can be released into the air

At these sites, particulates would have been discharged from the stacks

The heavy particulates will move down wind and settle on the soil

12

Wind Transport

Size of particulate matter

(microns)

13

Flowchart for fate and transport assessments of the atmosphere.

14

To the Soil

Sorbed chemicals can move into air or water.

Some chemicals do not want to go into water (hydrophobic).

Chemicals may attach (sorb) to soil particles.

Sorbed chemicals can slowly detach from soils and move into air or water.

15

Sources of fluids for the

generation of landfill leachate.

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Soil Particles

Water

Water Table

17

Groundwater Contaminants

Aqueous Groundwater

LNAPL (Light Nonaqueous-Phase Liquid)

DNAPL (Dense Nonaqueous-Phase Liquid)

18

Contamination from a Landfill

19

Contamination by TCE (trichloroethylene)

20

Lead in Soil

At many sites, lead is of concern.

Lead is an insoluble metal.

Lead tends to attach to soil particles

Lead can move if attached to very, very small particles called colloids.

21

Lead in Groundwater

Lead on surface

Size of particles exaggerated for illustration

Vertical Movement

Horizontal Movement

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Flowchart for fate and transport assessment for soils and groundwater

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To the Water

24

Water Soluble

Chemicals which move into water are referred to as being soluble - these chemicals prefer to be in water (hydrophilic).

Hydrophilic chemicals will tend to migrate far from where they are deposited.

25

Flowchart for fate and transport assessment in surface water and sediment.

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In Summary

Chemicals can be in air, soils or water.

Chemicals can move from from one medium to another.

Chemicals can be hydrophilic or hydrophobic, soluble or insoluble in water, volatile, semivolatile or nonvolatile.

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Subsurface Contaminant Transport

Process Type Process

Physical processes Advection, dispersion, diffusion, density stratification, NAPL flow, fractured media flow

Chemical processes Redox, ion exchange, complexation, precipitation, immiscible phase partitioning, sorption

Biological processes Aerobic/anaerobic degradation, cometabolism, biological uptake

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Types of Contaminant

Organic

Natural: Hydrocarbon

Synthetic : Pesticide

Inorganic

Heavy Metals: Cu(II), As(V), As(III), Cr(VI)

Chemistry: what you have learn for environmental chemistry class

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Organic Compounds

Usually containing C and H atoms

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Organic Compounds

Compound/

FamilyFormula

Specific

Gravity

Solubility

(mg/L)Kow

Vapor

Pressure

(mm Hg)

HenrysLaw

(unitless)

Fuels and derivatives

Benzene C6H6 0.879 1750 130 60 0.22

Toluene C6H5CH3 0.866 535 130 22 0.26

Ethylbenzene C8H10 0.867 152 1400 7 0.32

Phenol C6H6O 1.071 93,000 29 0.2 1.89 105

Ketones

Acetone CH3COCH3 0.791 inf 0.6 89 0.00104

Methyl ethyl ketone CH3COCH2CH3 0.805 2.68 105 1.8 77.5 0.00181

Halogenated aliphatics

Tetrachloroethene CCl2CCl2 1.631 150 390 14 1.21

Trichloroethene C2HCl3 1.466 1100 240 60 0.42

cis-1,2-Dichloroethene C2H2Cl2 1.27 3500 5 206 1.33

Vinyl chloride CH2CHCl 0.908 2670 24 266 3.58

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Physical and Chemical Properties

Water Solubility

Henrys Law Constant

Sorption and Partitioning

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Water Solubility

The ability of chemical to dissolve in to the water, usually the maximum reported

Function of Temperature, Pressure, and pH (especially inorganic chemical)

Terms Hydrophobic :

Water Hater

(non-polar molecule)

Hydrophilic :

Water Lover

(polar molecule)

+

+

-

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Inorganic Compounds Solubility

Hydrophilic Molecule

High solubility in water compared with organic molecule

Solubility greatly depending on pH

Can be calculated using the solubility products (Ks0 or Ksp) for each compound

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Mineral Solubility at pH =7

(mg/l)

Gibbsite Al2O3.2H2O 0.001

Quartz SiO2 12

Hydroxylapatite Ca5OH(PO4)3 30

Amorphous Silica SiO2+2H2O=Si(OH)4 120

Fluorite CaF2 17

Dolomite CaMg(CO3)2 480

Calcite CaCO3 500

Gypsum CaSO4.2H2O 2100

Sylvite KCl 264000

Epsomite MgSO4.7H2O 267000

Mirabillite Na2SO4.10H2O 280000

Halite NaCl 360000

Inorganic Compounds Solubility

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Solubilities of metal hydroxides as a

function of pH.

36 pH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Lo

g C

-14

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

H+

OH-

Al+3

Al(OH)4

-

AlOH+2

Al(OH)2

+

Al(OH)3

Al3(OH)

4

+5

Al13

O4(OH)

24

+7

AlTotal

Solubility Diagram for Al(OH)3(s)

37

Solubility Diagram for Cr(OH)3(s)

38 pH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Lo

g C

-14

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

H+OH

-

Fe+3

Fe(OH)4

-

FeOH+2

Fe(OH)2

+

Fe2(OH)

2

+4Fe

Total

Solubility Diagram for Fe(OH)3(s)

39 pH

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Lo

g C

-14

-13

-12

-11

-10

-9

-8

-7

-6

-5

-4

-3

-2

-1

0

H+

OH-

Zn+2

Zn(OH)4

-2

ZnOH+

Zn(OH)2 (aq)

Zn2(OH)

6

-2

ZnTotal

Zn(OH)3

-

Zn2(OH)

+3

Solubility Diagram for Zn(OH)2(s)

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Organic Compounds Solubility

Hydrophobic (non-polar) molecule

Usually low water solubility

Less pH dependent

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Henrys Law Constant

Transfer of contaminant from aqueous phase, directly to gas phase

Equilibrium partitioning similar to octanol-water partitioning

Partitioning equation known as Henrys Law

Hc is the relationship between partial pressure and aqueous concentration of component

Hc

Pc

[C]aq

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Henrys Law Constant

Chemicals that do not want to be in water (hydrophobic)

Chemicals that prefer to be in air (volatile organic compounds - VOCs)

Chemicals that can move into air, but do so more slowly (semi-volatile organic compounds - SVOCs)

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Sorption and Partitioning

Sorption association of dissolved or gaseous contaminant with a solid material

Adsorption surface process

Absorption internal process

Leads to retardation of the contaminant front (slower movement compared to tracer due to sorption)

Desorption reverse of either sorption process

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Soil Grain Sorption

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Linear Sorption Isotherm

Sorption linearly related to aqueous concentration. Partition coefficient is Kd or Kp

Kd is related to Kow

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Partitioning to Solid Phase

Octanol water partition

coefficient

Organic carbon partition

coefficient

Soil water partition

coefficient

water

octanol

C

CowK

aqueous

soil

C

CpK

aqueous

organic

C

CocK

ococp fKK

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Regression Equations for Sorption

Equation (a) No. (b) r2 (c)Chemical Class

RepresentedRef.

log koc = 0.55 log S + 3.64(S in mg/L)

106 0.71Wide variety, mostly

pesticides

Kenaga et al.,

(1978)

log koc = 0.54 log S + 0.44(S in mole fraction)

10 0.94

Mostly a romatic or

polynuclear aromatics;

two chlorinated

Karickhoff et al.,

(1979)

log koc = 0.557 log S + 4.277 (S in moles/L)

15 0.99Chlorinated

hydrocarbonsChiou et al., (1979)

log koc = 0.544 log kow + 1.377 45 0.74Wide variety, mostly

pesticidesKenaga et al, (1978)

log koc = 0.937 log kow 0.006 19 0.95Aromatics, polynuclear

aromatics, triazines and

dinitroaniline herbicides

Brown et al. (1981)

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Kp and foc

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Retarded v. Non-retarded Species

Sorption slows rate of advance of front

Sorbing fronts will eventually get there

Some compounds irreversibly sorb to soil

Relative

Concentration

(C/C )0

0

1

Retarded species

Nonretarded

species

x =v t._

b

ba

x

x =v t/(1+ k )ab

d

n

_.

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Chemical Analysis

Field

Rough situation of chemical contamination

Lab

More precise data and information

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Field Analytical Equipment

PID Analyzer Air sampling VOCs

Portable XRF

Metal Identification