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COMBINED ION EXCHANGE FOR THE SIMULTANEOUS REMOVAL OF DISSOLVED ORGANIC MATTER AND HARDNESS

By

JENNIFER NICOLE APELL

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING

UNIVERSITY OF FLORIDA

2009

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© 2009 Jennifer Nicole Apell

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To Dr. Treavor H. Boyer

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ACKNOWLEDGMENTS

I would like to thank Orica Watercare for providing the MIEX-Cl and MIEX-Na

resins and Neil Doty at the Cedar Key Water & Sewer District for assistance with

collecting raw water samples.

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TABLE OF CONTENTS Page

ACKNOWLEDGMENTS .................................................................................................. 4 

LIST OF TABLES ............................................................................................................ 7 

LIST OF FIGURES .......................................................................................................... 9 

ABSTRACT ................................................................................................................... 12 

CHAPTER

1 OVERVIEW AND OBJECTIVES ............................................................................. 13 

2 MATERIALS AND METHODS ................................................................................ 17 

Materials ................................................................................................................. 17 Preliminary Experimental Work ............................................................................... 18 Jar Test Procedure ................................................................................................. 18 Shaker Table Procedure ......................................................................................... 20 Regeneration of Ion Exchange Resin ..................................................................... 20 Analytical Methods .................................................................................................. 22 

3 RESULTS AND DISCUSSION ............................................................................... 24 

Cedar Key Water .................................................................................................... 24 Preliminary Experimental Work ............................................................................... 24 Magnetically-Enhanced Cation Exchange Treatment ............................................. 25 Combined Cation and Anion Exchange Treatment ................................................. 28 Simultaneous Versus Sequential Combined Ion Exchange Treatment ................... 29 Influence of Regeneration Parameters on Removal Efficiency ............................... 32 Applications of Combined Ion Exchange Treatment ............................................... 35 

4 CONCLUSIONS ..................................................................................................... 45 

Conclusions ............................................................................................................ 45 Recommendations for Further Research ................................................................ 45 

APPENDIX

A PRELIMINARY EXPERIMENTAL WORK RESULTS ............................................. 47 

B HARDNESS RESULTS FOR EXPERIMENTAL WORK ......................................... 51 

C DOC and TN RESULTS FOR EXPERIMENTAL WORK ........................................ 54 

D UV254 and SUVA RESULTS FOR EXPERIMENTAL WORK .................................. 58 

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E CHLORIDE and SULFATE RESULTS FOR EXPERIMENTAL WORK................... 61 

F EEMs for selected experimental work ..................................................................... 65 

LIST OF REFERENCES ............................................................................................... 69 

BIOGRAPHICAL SKETCH ............................................................................................ 73 

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LIST OF TABLES

Table Page 3-1 Characteristic of Cedar Key raw water used in ion exchange experiments. ....... 36 

3-2 Preliminary jar test results for fresh MIEX-Na resin. ........................................... 37 

3-3 Comparison of finished water quality for combined ion exchange and municipal drinking water ..................................................................................... 37 

3-4 Comparison of regeneration solutions prepared from DI water and tap water. ... 37 

A-1 Hardness results for preliminary experimental work. .......................................... 47 

A-2 Dissolved organic carbon and total nitrogen results for preliminary experimental work. ............................................................................................. 48 

A-3 UV254 and SUVA results for preliminary experimental work. ............................... 49 

A-4 Chloride and sulfate results for preliminary experimental work........................... 50 

B-1 Hardness removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na. ................................................................................................... 51 

B-2 Hardness removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl. . 51 

B-3 Hardness removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl. ........................................................................... 52 

B-4 Hardness removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl............................................................................... 52 

B-5 Hardness removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl with the reuse of a tap water regeneration solution (1 L singlet jar tests). ............................................................................. 53 

B-6 Hardness removal over time for 16 mL/L MIEX-Na. ........................................... 53 

C-1 Organics removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na. ................................................................................................... 54 

C-2 Organics removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl. . 55 

C-3 Organics removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl. ........................................................................... 56 

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C-4 Organics removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl............................................................................... 57 

D-1 UV254 removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na. ............................................................................................................ 58 

D-2 UV254 removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl. . 58 

D-3 UV254 removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl. ........................................................................... 59 

D-4 UV254 removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl............................................................................... 59

D-5 UV removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl with the reuse of a tap water regeneration solution (1 L singlet jar tests). .............................................................................................. 60 

E-1 Chloride addition and sulfate removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na. .................................................................... 61 

E-2 Chloride addition and sulfate removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl. ......................................................................................... 62 

E-3 Chloride addition and sulfate removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl. ........................................... 63 

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LIST OF FIGURES

Figure Page 2-1 Dosing flowchart for simultaneous and sequenced jar tests procedures. ........... 20 

3-1 Preliminary results for MIEX-Cl resin compared with MIEX-Cl regenerated before first use. ................................................................................................... 38 

3-2 Comparison of sulfate and DOC removal by MIEX-Cl resin with and without prior regeneration. .............................................................................................. 38 

3-3 Impact of brine and acid/base regeneration procedures on hardness removal by magnetic cation exchange using 16 mL/L MIEX-Na resin. ............................ 39 

3-4 Comparison of DOM and hardness removal by cation, anion, and combined ion exchange treatment using 2 mL/L MIEX-Cl and 16 mL/L MIEX-Na resins after three regeneration cycles. .......................................................................... 39 

3-5 Comparison of simultaneous and sequential ion exchange treatment on removal of (a) hardness, (b) DOC, and (c) UV254. All jar tests used 16 mL/L MIEX-Na resin and 2 mL/L MIEX-Cl resin. ......................................................... 40

3-6 Fluorescence EEMs for (a) Cedar Key water (5.4 mg C/L, 277 mg/L as CaCO3), (b) MIEX-Cl treatment (1.3 mg C/L, 273 mg/L as CaCO3), and (c) MIEX-Na treatment (4.7 mg C/L, 120 mg/L as CaCO3). ..................................... 42 

3-7 Effect of the ratio of NaCl to MIEX-Na resin on regeneration efficiency and hardness removal. .............................................................................................. 43 

3-8 Effect of varying reaction time and regeneration time on regeneration efficiency and hardness removal by MIEX-Na resin. .......................................... 43 

3-9 Regeneration efficiency and resin utilization based on the equivalence ratio used during regeneration. ................................................................................... 44 

3-10 Theoretical reduction in fouling caused by dissolved organic matter and calcium sulfate precipitation................................................................................ 44 

F-1 EEMs for (left) raw water and (right) 2 mL/L unregenerated MIEX-Cl treated water. .................................................................................................................. 65 

F-2 EEMs for (left) raw water, (center) 16 mL/L MIEX-Na treated water, and (right) 8 mL/L Amberlite-Na treated water. ......................................................... 65 

F-3 EEMs for (left) raw water and simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L unregenerated MIEX-Cl. ............................................................ 66 

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F-4 EEMs for (top left) raw water for (top right) simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L unregenerated MIEX-Cl and the (bottom left) raw water for (bottom right) 16 mL/L MIEX-Na and 2 mL/L MIEX-Cl that had been through four regeneration cycles. ....................................................................... 67 

F-5 EEMs for (left) raw water, (center) 16 mL/L MIEX-Na treated water, and (right) 2 mL/L MIEX-Cl treated water with resin that had been through two regeneration cycles. ........................................................................................... 68 

F-6 EEMs for (left) raw water (right) for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L MIEX-Cl that had been through two regeneration cycles. ................................................................................................................ 68 

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LIST OF ABBREVIATIONS DOC Dissolved organic carbon; experimentally defined as the carbon

concentration that can pass through a 0.45 μm nylon filter

DOM Dissolved organic matter

L Liter

M Molar

meq Milliequivalent

MIEX Magnetically-enhanced ion exchange resin manufactured by Orica Watercare

MIEX-Cl Anion MIEX resin loaded with chloride as the mobile counter ion

MIEX-Na Cation MIEX resin loaded with sodium as the mobile counter ion

min Minute

mL Milliliter

NOM Natural organic matter

Regen. Regenerated / Regeneration

rpm Rotations per minute

SUVA / SUVA254 Specific ultraviolet absorbance at 254 nm; defined as UV254 divided by the dissolved organic carbon concentration

TN Total nitrogen

UV254 Ultraviolet absorbance at 254 nm

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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 Engineering

COMBINED ION EXCHANGE FOR THE SIMULTANEOUS REMOVAL OF DISSOLVED ORGANIC MATTER AND HARDNESS

By

Jennifer Nicole Apell

December 2009

Chair: Treavor H. Boyer Major: Environmental Engineering Sciences

Dissolved organic matter (DOM) and hardness cations are two common

constituents of natural waters that substantially impact water treatment processes.

Anion exchange treatment, and in particular magnetic ion exchange (MIEX), has been

shown to effectively remove DOM from natural waters. An important advantage of the

MIEX process is that it is used as a slurry in a completely mixed flow reactor at the

beginning of the treatment train. Hardness ions can be removed with cation exchange

resins, although typically using a fixed bed reactor at the end of a treatment train. In this

research, the feasibility of combining anion and cation exchange treatment in a single

completely mixed reactor for treatment of raw water was investigated. The sequence of

anion and cation exchange treatment, the number of regeneration cycles, and the

chemistry of the regeneration solution were systematically explored. Simultaneous

removal of DOM (>70% dissolved organic carbon) and hardness (>50% total hardness)

was achieved by combined ion exchange treatment. This treatment would prove useful

for raw waters that are a mixture of groundwater and surface water and as a pre-

treatment for membrane systems as both DOM and calcium are major foulants.

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CHAPTER 1 OVERVIEW AND OBJECTIVES

Dissolved organic matter (DOM) and hardness cations (i.e., calcium and

magnesium) are common constituents of natural water that have a substantial impact

on physical-chemical unit processes and finished water quality. DOM is undesirable

because it imparts taste, odor, and color to water (Cohn et al., 1999); increases

chemical requirements for oxidation, coagulation, and disinfection (Kitis et al., 2007);

and is a precursor to disinfection byproducts (DBPs) (Johnson and Singer, 2004).

Hardness cations are primarily an economic concern for domestic water users. In

addition, many industrial processes require hardness-free water to prevent scaling. Of

increasing importance is the fact that both DOM and calcium have been shown to cause

reversible and irreversible fouling of membranes (Kimura et al., 2004; Saravia et al.,

2006; Fabris et al., 2007; Gray et al., 2007).

Coagulation is a common unit process used to remove DOM (Dempsey et al.,

1984), while lime softening is commonly used for removal of hardness (Mercer et al.,

2005). Coagulation and lime softening, however, have limitations. For example,

coagulation is limited to removal of ultraviolet-absorbing DOM (Archer and Singer,

2006), while lime softening is limited by the solubility of calcite and removal of carbonate

hardness (Stumm and Morgan, 1996). Therefore, alternative treatment processes for

removal of DOM and hardness are sought that could provide benefits over traditional

treatment. Ideally, a combined anion and cation exchange process is envisioned that

would remove both DOM and hardness, and thereby replace coagulation and lime

softening with a single unit process. The basis for combined ion exchange treatment for

removal of DOM and hardness is discussed below.

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Anion exchange, and in particular magnetic ion exchange (MIEX), is an alternative

to coagulation for DOM removal (Singer and Bilyk, 2002; Boyer and Singer, 2005; Jarvis

et al., 2008). MIEX resin is designed to be used as a slurry in a completely mixed flow

reactor or fluidized bed reactor (Boyer and Singer, 2006; Singer et al. 2009). As a result,

MIEX resin is used as a pre-treatment process to treat unfiltered water at the beginning

of a treatment train. MIEX resin has been previously shown to be very effective for

removal of DOM (Humbert et al., 2005; Kitis et al., 2007; Mergen et al., 2008; Zhang et

al., 2008). The substantial reduction in DOM by MIEX pre-treatment results in

decreased chemical requirements and reduced formation of DBPs (Johnson and

Singer, 2004; Kitis et al., 2007). In addition, research has shown that anion exchange

and MIEX pre-treatment have the potential to reduce membrane fouling by DOM when

resin carryover is controlled (Fabris et al., 2007; Zhang et al., 2008).

Cation exchange is an alternative to lime softening for hardness removal, and has

been extensively used for point-of-use water softening. In municipal water treatment

plants, cation exchange resin is traditionally used in a fixed bed reactor at the end of a

treatment train. Orica Watercare, the manufacturer of MIEX resin, recently developed a

weak-acid, magnetic cation exchange resin specifically designed for removal of

hardness. This resin is designed to be used in a suspended manner as a pre-treatment

process for hardness removal, similar to traditional MIEX resin for DOM removal.

Although cation exchange treatment is less common than softening in municipal water

treatment plants, recent research has shown that cation exchange is beneficial as a pre-

treatment for membrane systems (Cornelissen et al., 2009; Heijman et al., 2009).

Cation exchange is used to remove calcium and other divalent cations to prevent

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precipitation of sparingly soluble minerals, such as calcium sulfate and calcium

carbonate, and to minimize enhanced fouling by DOM on membrane surfaces (Li and

Elimelech, 2004). For example, Cornelissen et al. (2009) showed a 10% decrease in

irreversible fouling on an ultrafiltration membrane when raw water was treated with

cation exchange resin in a fluidized bed. Heijman et al. (2009) were able to achieve a

97% recovery in a nanofiltration system with the use of a cation exchange fluidized bed

that removed 99% of divalent cations. Thus, combined anion and cation exchange is

expected to substantially decrease membrane fouling by simultaneously removing DOM

and divalent cations.

Although previous researchers have investigated anion exchange for removal of

DOM and cation exchange for removal of hardness, none of the previous work

combined both anion and cation exchange into a single unit process for simultaneous

removal of DOM and hardness. It is also not known how the interactions between DOM

and hardness cations would affect the anion and cation exchange reactions. The

potential benefits of combined ion exchange for removal of DOM and hardness are

elimination of sludge from coagulation and lime softening, ability to use a single

completely mixed flow reactor or fluidized bed reactor at the head of the treatment train,

and removal of both organic and inorganic membrane foulants.

The overall goal of this work is to evaluate the removal of DOM and hardness by

combined anion and cation exchange treatment. The specific objectives of this work

are: (1) to evaluate the effectiveness of a magnetically-enhanced cation exchange resin;

(2) to compare removal efficiencies for anion, cation, and combined ion exchange

treatment; (3) to evaluate the effect that simultaneous versus sequential combined ion

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exchange treatment has on removal efficiencies; (4) to determine the influence of

regeneration parameters on removal efficiencies; and (5) to discuss additional

applications of combined ion exchange treatment.

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CHAPTER 2 MATERIALS AND METHODS

Materials

All experiments were conducted using groundwater from Cedar Key, FL collected

from Well 4 of the Cedar Key Water & Sewer District. Groundwater was collected in

November 2008 and January, February, and April 2009.

Magnetically enhanced anion and cation exchange resins, manufactured by Orica

Watercare, were evaluated in this work. In previous literature, the magnetic anion

exchange resin is referred to as MIEX resin. In this work, the magnetic anion exchange

resin will be referred to as MIEX-Cl (i.e., chloride is the mobile counter anion) and the

magnetic cation exchange resin will be referred to as MIEX-Na (i.e., sodium is the

mobile counter cation). Both resins have a polyacrylic backbone, macroporous

structure, and contain magnetic iron oxide. In addition, the MIEX-Cl and MIEX-Na resins

are designed to be used in a suspended manner in a completely mixed flow reactor, as

discussed previously. The MIEX-Cl resin is a strong-base anion exchange resin with

quaternary amine functional groups, and has a volumetric anion exchange capacity of

0.52 milliequivalents (meq) per mL resin (Boyer and Singer, 2008). Additional

discussion of anion exchange resin properties is provided elsewhere (Boyer and Singer,

2008). The MIEX-Na resin is a weak-acid cation exchange resin with carboxylic acid

functional groups. Weak-acid cation exchange resins are typically used in the hydrogen-

form at acidic pH values (Clifford, 1999). At neutral to basic pH values, weak-acid resins

function much like strong-acid resins, and are typically used in the sodium form (Clifford,

1999). The MIEX-Na resin was assumed to have a cation exchange capacity of 0.52

meq/mL because it was functionalized from the same starting material as the MIEX-Cl

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resin. All ion exchange resins were dosed volumetrically by measuring the volume of

wet settled resin using a graduated cylinder.

ACS grade chemicals were used for all experimental procedures and analytical

methods. Standard chemicals used for total organic carbon and total nitrogen analyses

were provided by the manufacturer. Deionized (DI) water was used to prepare all

chemical reagents and standards. Glassware was cleaned by rinsing with DI water and,

if necessary, a 6% nitric acid solution.

Preliminary Experimental Work

Preliminary experiments were conducted to determine the MIEX dose that could

remove 50% total hardness and 50% dissolved organic carbon (DOC) from Cedar Key

raw water. MIEX-Cl was used as delivered and MIEX-Na was regenerated to convert all

mobile ions to sodium. The regeneration procedure is described in the Regeneration of

Ion Exchange Resin section below. After MIEX-Cl resin was regenerated, a substantial

increase in DOC and UV254 removal was seen. MIEX-Cl was then regenerated in the

same manner as MIEX-Na before all further tests.

Jar Test Procedure

A Phipps & Bird PB-700 jar tester with 2 L square jars was used to conduct batch

tests with ion exchange resin. Two liters of Cedar Key raw water was added to each jar.

The ion exchange resin was measured and added to the jars. The resin was mixed for

20 min at 100 rpm and allowed to settle for 30 min. A sample was taken from each jar

from a spigot in the jar. All ion exchange experiments were conducted using duplicate

doses of ion exchange resin, and all results are shown as average values with error

bars corresponding to one standard deviation for duplicate resin doses, except where

noted otherwise.

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Individual anion and cation exchange jar tests were conducted as described in the

previous paragraph. In addition, three types of combined ion exchange experiments

were performed: (1) simultaneous anion and cation exchange, (2) sequential anion

exchange followed by cation exchange (Sequence 1), and (3) sequential cation

exchange followed by anion exchange (Sequence 2). For all combined ion exchange

experiments, anion and cation exchange resins were measured separately in graduated

cylinders and then added to a single jar at the appropriate time during the experiment.

Initial jar tests were conducted with fresh ion exchange resin, which is defined in the

Regeneration of Ion Exchange section below. After the initial jar test, the resin from the

duplicate jars was combined for regeneration, which is also described in the same

section. The combined resin was split into duplicate doses with the assumption that the

anion and cation exchange resins were evenly distributed. Subsequent jar tests were

conducted with regenerated resin, and the tests are referred to as the number of times

the resin was regenerated (e.g., regen. 1×). Sequences 1 and 2 followed the general

procedure described above, with the following additional steps. Three jars were used for

the first stage of treatment with either anion or cation exchange resin. After the first

treatment stage, at least four liters of treated water was decanted from the three jars,

and two liters each of treated water was transferred to two clean jars. The

complementary ion exchange resin was added to the new jars for the second stage of

treatment. A sample from each jar was taken after the second treatment stage.

Raw and treated water samples were measured for pH, total hardness, alkalinity,

ultraviolet (UV) absorbance, dissolved organic carbon (DOC), total nitrogen (TN),

fluorescence intensity, chloride, sulfate, and nitrate.

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21

resin, based on an ion exchange capacity of 0.52 meq/mL. For example, 2 mL/L of

MIEX-Cl resin has a capacity of 1.04 meq/L, and a 10 times sodium chloride solution

has a concentration of 10.4 meq/L as chloride (or 10.4 mM as chloride). Although MIEX-

Cl is shipped in the chloride form, preliminary jar tests showed an increase in DOC

removal with regeneration, suggesting that the anion exchange sites on the virgin resin

were not fully saturated with chloride. MIEX-Na is shipped as a mixture of sodium and

hydrogen mobile ions, so it was regenerated to convert all mobile ions to sodium.

The resins were regenerated after each jar test as follows. Excess water was

decanted from the jars and the resin was rinsed once with DI water. All regeneration

solutions had a sodium chloride concentration of ~2 M, unless noted otherwise. The

baseline regeneration procedure used a brine solution that contained 25 times more

sodium chloride (on a meq/L basis) than was theoretically available on the resin. This

was achieved by adjusting the ratio of the volume of regeneration solution to the volume

of MIEX resin. The regeneration solution and resin were mixed on a stir plate for 30 min

and allowed to settle for 10 min before decanting the brine. The container was filled with

DI water, mixed for 10 min, settled for 10 min, decanted, and repeated for a second

time. The cation and anion exchange resins were combined for the simultaneous ion

exchange tests, so the amount of sodium chloride used for regeneration was dependent

on the amount of cation exchange resin present. Consequently, the brine solution was 8

times stronger for the anion exchange resin than it was for the cation exchange resin

because of the dosages of resin. For Sequences 1 and 2, the cation and anion

exchange resins were regenerated separately, and therefore, the ratio of sodium

chloride to resin, on a meq/L basis, was constant at 25 for both resins.

22

The MIEX-Na resin was also regenerated using a series of acid and base

solutions as follows. The resin was stirred in DI water while hydrochloric acid was added

until pH 3 was reached. This step converts the resin to the hydrogen form. Sodium

hydroxide was then added until pH 11 to convert the resin to the sodium form. The

same rinsing procedure was followed.

Analytical Methods

Samples requiring filtration were filtered through 0.45 µm nylon membrane filters

(Millipore). All filters were pre-rinsed with 500 mL of DI water followed by 15 mL of

sample. Filtered water was used for all analyses except pH, alkalinity, and total

hardness. An Accumet AP71 pH meter with a pH/ATC probe was used to measure pH.

The pH meter was calibrated before each use with pH 4, 7, and 10 buffer solutions.

Alkalinity and total hardness were determined following Standard Method 2320 and

2340, respectively (American Public Health Association, (1998)).

UV absorbance at 254 nm (UV254) was measured on a Hitachi U-2900

spectrophotometer using a 1 cm quartz cell. Fluorescence excitation-emission matrix

(EEM) spectra were collected on a Hitachi F-2500 fluorescence spectrophotometer

using a 1 cm quartz cell. Samples were scanned at 5 nm increments over an excitation

(EX) wavelength = 200–500 nm and at 5 nm increments over an emission (EM)

wavelength = 200–600 nm. The raw EEMs were processed in MATLAB following

published procedures (Cory and McKnight, (2005)). A DI water EEM, which was

analyzed daily, was subtracted from the sample EEM; the area under the Raman water

peak (EX = 350 nm) was calculated for DI water; intensity values of the sample EEM

were normalized by Raman water area; and EEMs were plotted in MATLAB using the

contour function with 20 contour lines.

23

DOC and TN were measured on a Shimadzu TOC-VCPH total organic carbon

analyzer equipped with a TNM-1 total nitrogen measuring unit and an ASI-V

autosampler. All DOC and TN samples were measured twice with average values

reported. The relative difference between DOC and TN duplicate measurements was

<10% and <15%, respectively. The relative difference was calculated by subtracting the

two values and dividing by the average. Standard checks were within 10% of the known

value.

Chloride, nitrate, and sulfate were measured on a Dionex ICS-3000 ion

chromatograph equipped with IonPac AG22 guard column and AS22 analytical column.

All inorganic anions were measured in duplicate with average values reported. The

relative difference between duplicate measurements was <5%. Standard checks were

within 10% of the known value. The aqueous concentration of metal cations was

determined by acidifying samples to pH <2 with concentrated nitric acid (Trace Metal

Grade, Fisher Scientific) and measuring on an ICP-AES (Thermo Jarrell Ash) as

described in the US EPA Method 6010B.

24

CHAPTER 3 RESULTS AND DISCUSSION

Cedar Key Water

The average composition of Cedar Key groundwater is shown in Table 3-1. The

minimum and maximum parameter values show that the water quality was relatively

constant over the study timeframe, as would be expected for a groundwater. The

relatively high concentrations of DOC and hardness in Cedar Key groundwater are

common for a groundwater that has been infiltrated by a surface water. Furthermore,

this is a water source that requires substantial treatment to prevent the problems

associated with elevated concentrations of DOM and hardness, such as DBP formation

and membrane fouling. The average specific UV254 absorbance (SUVA254) of Cedar Key

raw water was 3.1 L/mgC·m, which together with the low sulfate concentration indicates

that MIEX-Cl treatment will be effective for DOM removal (Boyer and Singer, 2006).

Greater than 90% of the hardness was as calcium. This is important because calcium

and DOM form strong inner-sphere complexes, while magnesium and DOM do not

interact (Kalinichev and Kirkpatrick, 2007).

Preliminary Experimental Work

Three preliminary doses of 0.5, 1, and 2 mL of virgin MIEX-Cl resin per L of Cedar

Key raw water were tested in the preliminary work. The dose of 2 mL/L was found to

remove about 53% of DOC and 60% of UV254 and was therefore chosen for all further

research. The DOC, UV254, TN, and SUVA254 results from the three preliminary doses

can be found in Figure 3-1. Also located in that figure for comparison is the results from

a 2 mL/L MIEX-Cl dose that had been regenerated beforehand to become fresh resin. It

can be seen that UV254 and DOC removal steadily increase as the resin dose increases

25

and that there is a small decline in SUVA. The raw water SUVA for the preliminary tests

was 3.4 L/mgC·m, which means that the dose of 2 mL/L caused a decrease of 0.5 to

reach the SUVA of 2.9 L/mgC·m. The raw water SUVA for the 2 mL/L regenerated

MIEX-Cl resin dose was 3.0 L/mgC·m and decreased to 1.5 L/mgC·m, a difference of

1.5. This difference is caused by a greater removal of UV254 compounds than overall

DOC.

Figure 3-2 shows the difference that regeneration causes in sulfate and DOC

removal for the 2 mL/L MIEX-Cl dose. Only a 4% increase in sulfate removal is seen

while there is a 22% increase in DOC removal. This is significant because sulfate is the

major competitor of organic matter for ion exchange sites on MIEX-Cl resin.

All supplementary data for preliminary work can be found in Appendix A.

Magnetically-Enhanced Cation Exchange Treatment

Preliminary jar tests were conducted using the magnetic cation exchange resin

(i.e., MIEX-Na) to evaluate the relationship between hardness removal and resin dose.

The treatment goal was to achieve at least 50% hardness removal. The change in water

chemistry following magnetic cation exchange treatment is shown in Table 3-2. The

results are from jar tests using fresh MIEX-Na resin that was regenerated with sodium

chloride. A linear regression line was fit to the resin dose and hardness removal data

(R2 = 0.997), and showed that 3.6% hardness removal is achieved per mL/L of MIEX-

Na resin. Furthermore, MIEX-Na resin removed 0.40 meq of hardness per meq of resin

at 16 mL/L, which means that the resin was 40% saturated with calcium. Complete

removal of hardness from Cedar Key water at 16 mL/L MIEX-Na resin is equal to 66%

of the cation exchange sites occupied with calcium. Thus, the resin has sufficient cation

exchange capacity to remove all hardness at 16 mL/L MIEX-Na resin. The previous

26

calculations used a MIEX-Na resin capacity of 0.52 meq/mL, and assumed that 20 min

was sufficient time for ion exchange. The resin capacity is a reasonable assumption

based on previous work using MIEX-Cl (Boyer and Singer, 2008). The mixing time is

also reasonable for an inorganic cation exchange reaction (Kunin and Barry, 1949).

Weak-acid cation exchange resin in the sodium-form has been previously reported to

have a high affinity for calcium (Kunin and Barry, 1949), so the excess cation exchange

capacity remaining after treatment suggests that MIEX-Na resin was incompletely

converted to the sodium form. Moreover, weak-acid resin in the hydrogen-form has a

very low affinity for sodium and calcium (Kunin and Barry, 1949). Therefore, incomplete

conversion of magnetic cation exchange resin to the sodium-form is a likely explanation

for the hardness removal results.

Table 3-2 shows that MIEX-Na resin also removed UV-absorbing substances and

DOC. This is surprising because DOM is rich in carboxylic acid functional groups, which

give DOM a net negative charge over the pH range of natural waters (Ritchie and

Perdue, 2003) and allow DOM to take part in anion exchange reactions (Boyer et al.,

2008). The increase in chloride suggests the possibility of anion exchange between

DOM and resin-phase chloride. Because MIEX-Na resin is synthesized from the same

starting material as MIEX-Cl resin it is possible that there are residual anion exchange

functional groups on the cation exchange resin. However, the sulfate results do not

support the anion exchange hypothesis and suggest that the chloride release is an

artifact of regenerating the resin in sodium chloride solution. Alternative explanations for

DOM removal by cation exchange resin include adsorption of DOM to the resin matrix

and cation exchange uptake of DOM-Ca+ complexes. Boyer and Singer (2008)

27

previously showed no removal of DOC by a weak-acid, magnetic cation exchange resin,

so adsorption is unlikely. The fraction of DOM that is complexed with calcium (i.e.,

[DOM-Ca+]/[DOM]) can be estimated using the work of Lin et al. (2005), where DOM-

Ca+ is formed by binding of calcium and carboxylic acid groups of DOM (Kalinichev and

Kirkpatrick, 2007). Assuming that the total hardness (274.5 mg/L as CaCO3) is as

calcium (2.745×10-3 M Ca2+) and using the stability constant for Suwannee River fulvic

acid (Ks = 50 M-1), [DOM-Ca+]/[DOM] = Ks[Ca2+] = 0.14. The previous calculation

supports the idea that a fraction of DOM is removable by cation exchange resin. Cation

exchange uptake of DOM-Ca+ is further supported by results for Amberlite 200 cation

exchange resin shown in Table 3-2. Amberlite 200 shows substantial removal of

hardness and no removal of UV254, DOC, chloride, or sulfate. The polystyrene matrix of

Amberlite 200C allows transport of calcium but hinders the transport of DOM and DOM-

Ca+ (Boyer and Singer, 2008). Thus, cation exchange uptake of DOM-Ca+ is a

reasonable explanation for DOM removal by MIEX-Na resin.

All subsequent cation exchange jar tests were conducted using 16 mL/L MIEX-Na

resin, because this resin dose achieved greater than 50% hardness removal.

The impact of the regeneration procedure on the efficiency of hardness removal by

MIEX-Na resin was also investigated. The MIEX-Na resin was regenerated using a

brine solution and an acid/base solution. Figure 3-3 shows the effect of the regeneration

procedure on hardness removal. Regeneration of MIEX-Na resin with brine solution

results in a measureable advantage in hardness removal as compared with acid/base

regeneration for the fresh resin test conditions. During the acid/base procedure, the

milliequivalents of sodium added to solution was equal to 1 times the resin capacity,

28

while the brine regeneration was conducted with 25 times more sodium than resin. The

subsequent regeneration test results show that the regeneration procedure had a

dramatic impact on hardness removal. For example, hardness removal by resin

regenerated with brine decreased from 66% for the fresh resin to 52% for the

regenerated resins (i.e., regen. 1× and 2×). In contrast, hardness removal by resin

regenerated with acid/base solution decreased from 51% for the fresh resin to <10% for

the regenerated resins (regen. 1× and 2×). The difference in hardness removal due to

the brine and acid/base regeneration procedures is a result of the affinity of the

carboxylic acid functional groups for hydrogen, sodium, and calcium (Kunin and Barry

(1949)). Thus, the acid/base regeneration procedure was found to be ineffective at

regenerating the resin. All subsequent regenerations were conducted using the brine

regeneration procedure.

Combined Cation and Anion Exchange Treatment

MIEX-Na and MIEX-Cl resins were used separately and combined to treat Cedar

Key water, and removal of DOC, UV254, and hardness was measured as shown in

Figure 3-4. The doses of 2 mL/L of MIEX-Cl resin and 16 mL/L MIEX-Na resin were

used for all jar tests. All results are for ion exchange resin that has gone through three

regeneration cycles, which will be discussed in more detail in following sections. As

seen previously, MIEX-Na resin removed 54% of hardness and removed 19% and 21%

of DOC and UV254, respectively. MIEX-Cl resin removed a substantial amount of DOM

(76% DOC and 89% UV254) and a small fraction of hardness. When MIEX-Na and

MIEX-Cl resins were combined, hardness removal was approximately equal to cation

exchange treatment alone, while DOC and UV254 removal was approximately equal to

anion exchange treatment alone. Thus, removal of hardness and DOM was not

29

cumulative for combined anion and cation exchange treatment. Hardness removal is

explained by DOM-Ca+ representing a small fraction of total calcium, while DOM

removal is explained by DOM-Ca+ retaining deprotonated carboxylic acid groups in the

presence of calcium (Bose and Reckhow (1997)). It is important to emphasize that

combined anion and cation exchange treatment is an effective strategy whereby a

single unit process can remove 71% DOC and 58% hardness, as can be seen in Figure

3-4.

The Cedar Key Water & Sewer District uses the following treatment train:

permanganate oxidation at the well head; MIEX-Cl to remove DOM; lime softening to

remove hardness; sand filtration; and chlorine disinfection. Table 3-3 shows a

comparison of water quality data from laboratory-scale, combined ion exchange

treatment and full-scale treatment. The combined ion exchange process produces water

that has a finished water quality near drinking water standards.

Simultaneous Versus Sequential Combined Ion Exchange Treatment

Sequential cation and anion exchange treatment was tested and compared with

simultaneous ion exchange treatment, which was the focus of the previous section. The

basis for sequential ion exchange was to maximize the removal of hardness and DOM

as would be achieved by the summation of hardness and DOM removal by individual

cation and anion exchange in Figure 3-4. Figures 3-5(a–c) show the removal of

hardness, DOC, and UV254 as a function of the ion exchange treatment scenario and

number of regeneration cycles. For fresh resin, removal of DOC and UV254 was

consistently greater for sequential ion exchange (both Sequences 1 and 2) as

compared with simultaneous ion exchange, but hardness removal was greater for

simultaneous treatment. Furthermore, there was little difference in hardness and DOM

30

removal for Sequences 1 and 2. These results support the assertion that separate

cation and anion exchange treatment, using fresh resin, achieves cumulative removal of

hardness and DOM as would be expected from the results in Figure 3-4. However, the

results show there is only a slight cumulative effect otherwise nearly 100% DOC

removal would have been seen by the third regeneration cycle.

Evaluating the performance of ion exchange resin over multiple regeneration

cycles is an important contribution of this work, because previous studies have focused

on testing fresh resin or simulating continuous operation (Mergen et al., (2008) and

references therein). This is the first study to comprehensively investigate the

regeneration of MIEX resin on a batch treatment basis. The importance of the

regeneration process is illustrated in comparing the removal of hardness and DOM as a

function of the number of regeneration cycles. For example, removal of hardness, DOC,

and UV254 all individually approached similar values for the three ion exchange

treatment scenarios after three regeneration cycles. A different conclusion would have

been reached if only fresh resin was evaluated.

Although the effect of the ion exchange treatment scenario was moderated by

multiple regeneration cycles, the behavior of hardness and DOM differed over the

course of the regeneration process. For example, over the course of three regeneration

cycles total hardness removal decreased by 9% for Sequences 1 and 2, whereas

hardness removal, after an initial drop in removal, increased over the course of the

three regeneration cycles for simultaneous treatment. It is not clear why the multiple

regeneration cycles affected hardness removal by Sequences 1 and 2. In contrast to

hardness removal, DOC and UV254 removal tended to increase for the three ion

31

exchange treatment scenarios over the course of three regeneration cycles.

Furthermore, UV254 removal increased by a greater extent than DOC removal as

indicated by SUVA254. For fresh resin, SUVA254 values for Simultaneous, Sequence 1,

and Sequence 2 treated samples were 2.3, 2.1, and 2.1 L/mgC·m, respectively.

Following three regeneration cycles, SUVA254 values for Simultaneous, Sequence 1,

and Sequence 2 treated samples were 1.7, 1.8, and 1.6 L/mgC·m, respectively.

Increased DOM removal upon regeneration was unexpected, because the fresh resin

was regenerated before it was used to ensure that it had full anion exchange capacity.

Thus, it is not clear why removal of hardness and DOM follow different trends with

respect to the ion exchange treatment scenario and number of regeneration cycles.

Sulfate and TN were also analyzed to study simultaneous versus sequential ion

exchange treatment. Sulfate removal averaged 82% for Simultaneous, Sequence 1, and

Sequence 2 for fresh resin and regenerated resin. Similarly, TN removal was

independent of the ion exchange treatment scenario and regeneration cycle, and

removal averaged 30%. The TN removed is believed to be part of the DOM that was

removed, because nitrate was < 0.01 mg N/L in the raw water. Greater removal of DOC

relative to TN has been reported previously for MIEX-Cl resin (Boyer et al., 2008). The

overall order of treatment efficiency for combined ion exchange treatment, considering

both simultaneous and sequential treatment for fresh and regenerated resin, was UV254

~ sulfate > DOC > hardness > TN.

Fluorescence EEMs were analyzed to help understand the differences in hardness

and DOM removal by anion and cation exchange. Figure 3-6 shows fluorescence EEMs

for Cedar Key raw water, anion exchange treated water, and cation exchange treated

32

water, and the corresponding DOC and hardness concentrations. The EEM for Cedar

Key water had three peaks: Peak 1 at EM = 440 nm and EX = 265 nm, Peak 2 at EM =

300 nm and EX = 275 nm, and Peak 3 at EM = 300 nm and EX = 230 nm. Peak 1 is

attributed to terrestrially derived DOM, while Peaks 2 and 3 are likely attributed to

microbially derived DOM (Coble, 1996; Chen et al., 2003). Although it is not known to

what extent DOM-Ca+ complexes are contributing to the fluorescence EEM spectra,

previous researchers have shown that DOM-metal complexes affect fluorescence

intensity (Ohno et al., 2008; Yamashita and Jaffe, 2008). Raw water collected from

Cedar Key consistently showed these three peaks as can be seen in Appendix F. Anion

exchange treatment substantially decreased all fluorescence peaks, with a

corresponding decrease in DOC of 5.4 to 1.3 mg C/ L. In contrast, cation exchange

treatment only decreased fluorescence Peaks 2 and 3, with corresponding decrease in

DOC of 5.4 to 4.7 mg C/L. Thus, the cation exchange resin appears to selectively

remove microbially derived DOM fluorophores, which may also correspond to DOM that

preferentially binds calcium.

Influence of Regeneration Parameters on Removal Efficiency

It was shown that regeneration with brine was more effective than regeneration

with an acid/base solution. As a result, the impact of the meq NaCl/meq MIEX resin

ratio, regeneration time, and regeneration solution chemistry were investigated to learn

more about the brine regeneration process. Hardness removal as a function of sodium

chloride concentration in the regeneration solution is shown in Figure 3-7, where 25

meq NaCl/meq MIEX-Na resin is the baseline regeneration concentration. The data

correspond to treatment with 16 mL/L MIEX-Na resin after one regeneration cycle.

There is a clear trend of increasing hardness removal with increasing concentration of

33

sodium chloride in the regeneration solution. At a regeneration level of 50 meq

NaCl/meq MIEX-Na resin, hardness removal approached 70%, and the theoretical

saturation of the resin with calcium and magnesium was 44% (compared to 36% for

baseline regeneration). This suggests that more resin capacity would be available if the

resin was regenerated in a brine solution with a regeneration ratio greater than 50 meq

NaCl/meq MIEX Na resin.

In Figure 3-8, the reaction time and regeneration time are varied to measure the

effects on hardness removal. The reaction time is defined as the length of time fresh

resin is mixed in raw water, while the regeneration time is the length of time exhausted

resin is mixed in concentrated sodium chloride solution. The results show that the

exchange of hardness ions with sodium ions can take place within five minutes in the

raw water and the regeneration solution. Although these results show that the cation

exchange process is relatively quick, longer reaction times are needed to transfer DOM

to/from the anion exchange resin in a combined ion exchange treatment process (Boyer

and Singer, 2005).

All regeneration experiments, up to this point, were conducted using regeneration

solution prepared with DI water that contained negligible amounts of hardness and

alkalinity. At a full-scale water treatment plant, however, chemical reagents are

prepared with finished drinking water that may contain measurable inorganic chemicals.

Thus, a set of regeneration experiments were conducted to compare hardness removal

using regeneration solutions prepared from DI water and tap water. The tap water was

from Gainesville, FL and had a hardness of 146 mg/L as CaCO3 and an alkalinity of 42

mg/L as CaCO3. The combined ion exchange resins were regenerated using a tap

34

water regeneration solution following the baseline procedure. Table 3-4 shows that

hardness removal by 16 mL/L of fresh MIEX-Na resin was approximately equal for DI

water and tap water regeneration solutions. This means that hardness cations present

in the tap water had little to no effect on the regeneration process. In addition, removal

of UV254-absorbing substances was consistent regardless of the use of DI or tap water

to prepare the regeneration solution.

The impact of reusing the regeneration solution was also investigated. Hardness

removal decreased by an average of 14% after each regeneration cycle with “used”

regeneration solution for both DI water and tap water, as shown in Table 3-4. Before the

last regeneration, ~2,563 mg/L (48.4 meq/L) of sodium carbonate was added to the tap

water regeneration solution. This amount corresponded to the theoretical

milliequivalents of hardness cations added to the “used” regeneration solution during

the previous regeneration cycles, based on calculations. A precipitate was immediately

formed by addition of sodium carbonate to the used regeneration solution. The

precipitate was not characterized, but it was likely a calcium carbonate mineral. The

regeneration solution was then filtered through a 1.6 µm GF/A filter (Whatman) to

remove the precipitate. The resin was regenerated using the sodium carbonate treated

solution and tested in a jar test. The hardness removal increased by 13% from the

previous jar test. This suggests that the regeneration solution can be more effectively

reused if calcium is precipitated out of solution, especially if a sodium salt of carbonate

is used. Furthermore, calcium sulfate may precipitate during regeneration of combined

ion exchange resin, which would benefit both anion and cation exchange regeneration.

Thus, the regeneration efficiency of combined ion exchange resin can be increased by

35

the addition of sodium or the removal of calcium from the regeneration solution;

however, increasing resin contact time with the regeneration solution or raw water has

no effect.

An experiment to determine the regeneration efficiency and resin utilization over a

range of meq NaCl to meq MIEX-Na resin equivalence ratios was conducted. Figure 3-9

shows that regeneration efficiency increases as the equivalence ratio decreases

meaning that a higher percentage of the sodium is transferred to the resin at lower

equivalence ratios. However, the amount of calcium removed from the resin increases

as the equivalence ratio increases up to an equivalence ratio of 100. Therefore, the

desired balanced between sodium chloride usage and resin regeneration efficiency

must be chosen by the water treatment plant.

Applications of Combined Ion Exchange Treatment

Previous researchers have separately investigated anion and cation exchange

treatment and shown these processes to be a possible pre-treatment for membrane

systems to reduce fouling (Fabris et al., 2007; Heijman et al., 2009). However, the

impact of combined anion and cation exchange treatment on the reduction of

membrane fouling has not been previously demonstrated. Figure 3-10 shows the

theoretical reduction in membrane fouling as a result of prevention of calcium sulfate

precipitation and removal of DOM, both of which are major foulants of membrane

systems (Shih et al., 2005; Lin et al., 2006; Jarusutthirak et al., 2007). Although chloride

and sodium are added to the ion exchange treated water, Jarusutthirak et al. (2007)

showed that these monovalent ions cause less flux decline than the divalent ions of

sulfate, carbonate, and calcium. The membrane fouling potentials were calculated as:

inorganic fouling potential = {[Ca2+][SO42-]}/{[Ca2+]0[SO4

2-]0} and organic fouling potential

36

= [DOC]/[DOC]0, where the subscript 0 indicates initial concentration. The ion exchange

treatment scenarios are as follows: Cation = 16 mL/L MIEX-Na resin, Anion = 2 mL/L

MIEX-Cl resin, and Cation + Anion = 16 mL/L MIEX-Na and 2 mL/L MIEX-Cl resins.

Although individual cation and anion exchange treatment can reduce the fouling

potential, the largest reduction in fouling is achieved with combined ion exchange

treatment. It is expected that combined ion exchange treatment will be effective for

reducing membrane fouling potential for a wide range of DOM, sulfate, and calcium

concentrations.

Table 3-1. Characteristic of Cedar Key raw water used in ion exchange experiments Parameter Average Minimum Maximum pH 7.58 7.09 8.06 UV254 (cm-1) 0.171 0.168 0.186 DOC (mg C/L) 5.6 5.0 6.1 TN (mg N/L) 0.32 0.25 0.38 Cl- (mg/L) 11.8 10.5 14.3 SO4

2- (mg/L) 20.9 16.9 31.5 Hardness (mg/L CaCO3) 274.5 264.5 287.5 Alkalinity (mg/L CaCO3) 244a - - Calcium (mg/L) 103a - - aBased on one measurement from January 2009 water; other cations (mg/L): Na+ = 5.49, K+ = 0.38, Mg2+ = 4.18, Sr2+ = 0.87.

37

Table 3-2. Preliminary jar test results for fresh MIEX-Na resin MIEX-Na (mL/L) Hardness UV254 DOC Chloride Sulfate 2b 7.7 1.6 3.3 -0.4 0.1 4b 12.3 3.2 4.4 -2.6 -2.6 16c 57.4 ± 0 16.0 ± 0 6.7 ± 3.5 -8.7 ± 5.0 3.8 ± 0.1 Amberlite 200Cc,d 76.5 ± 0 -1.1 ± 0.8 -2.3 ± 1.2 -1.0 ± 0.1 -1.2 ± 0.3 a All results are percent removal. b Single resin dose. c Duplicate resin dose; average value ± one standard deviation reported. d Jar test experiment with resin dose of 8 mL/L. Table 3-3. Comparison of finished water quality for combined ion exchange and

municipal drinking water Parameter Combined ion exchangea Municipal drinking waterb

pH 7.70 8.08 DOC (mg C/L) 1.70 1.1 Hardness (mg/L as CaCO3) 111.6 172.8 Chloride (mg/L) 48.8 59.7 Sulfate (mg/L) 3.1 1.1 a Cation + Anion in Figure 2. b Cedar Key Water & Sewer District; August 2009. Table 3-4. Comparison of regeneration solutions prepared from DI water and tap water Hardness removal Regeneration solution DI water Tap watera

Fresh regeneration solution 58% 62% Reused regeneration solution (1×) 44% 45% Reused regeneration solution (2×) - 33% Na2CO3 added to reused solution - 46% a Experiments with tap water were 1 L, single jar tests.

Figure 3

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Figure 33-5. Continuued.

41

42

Figure 3-6. Fluorescence EEMs for (a) Cedar Key water (5.4 mg C/L, 277 mg/L as CaCO3), (b) MIEX-Cl treatment (1.3 mg C/L, 273 mg/L as CaCO3), and (c) MIEX-Na treatment (4.7 mg C/L, 120 mg/L as CaCO3).

(a)

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45

CHAPTER 4 CONCLUSIONS

Conclusions

The overall goal of this work was to evaluate combined anion and cation exchange

treatment for removal of DOM and hardness. The major conclusions of this work are

summarized as follows:

• Anion and cation exchange resins can be used in a single completely mixed reactor to remove DOM (>70% DOC) and hardness (>50% hardness) simultaneously. This allows for the most efficient use of the brine regeneration solution.

• Although sequential treatment showed slightly better removal for fresh resin, the differences between sequential and simultaneous treatment were dampened by the third regeneration cycle.

• The behavior of the MIEX-Cl and MIEX-Na resin changed with regeneration prior to first use and over the regeneration cycles.

• Increasing the ratio of meq Na+/meq MIEX-Na resin from 10 to 50 resulted in increased hardness removal. However, increasing the ratio of meq Cl-/meq MIEX-Cl resin from 25 to 200 did not improve DOC or UV254 removal.

• A higher percentage of sodium in the regeneration solution is transferred to the MIEX-Na resin as the meq Na+/meq MIEX-Na ratio decreases; however, the meq of calcium removed decreases as the meq Na+/meq MIEX-Na ratio decreases.

• The regeneration solution can be used repeatedly, especially if hardness cations are precipitated out of solution. Precipitation may also be used to precipitate anions such as sulfate. An economic analysis should be conducted to determine if precipitation of inorganic compounds or the use of a new NaCl solution is more feasible.

• Tap water, which contained measureable hardness and alkalinity, provided the same regeneration efficiency as hardness-free, DI water.

Recommendations for Further Research

• The results from MIEX-Na tests showed variability in hardness removal under the same test conditions. This suggests that the batches of MIEX-Na resin can have varying resin capacities. The capacity of each batch should be determined in order

46

to obtain normalized results and to test the assumption that the average capacity is 0.52 meq/mL resin.

• Combined MIEX resin should be regenerated at varying meq NaCl/meq MIEX-Na ratio based on molarity instead of volume of a 2 M solution. This would determine if the molarity of the solution affects the regeneration process.

• The treatment process presented here should be tried with more traditional ion exchange resins such as the Amberlite series.

47

APPENDIX A PRELIMINARY EXPERIMENTAL WORK RESULTS

Table A-1. Hardness results for preliminary experimental work

Hardness Experiment Conc. C/Co % Rem. St. Dev. St. Dev./Co

0.5 mL/L M-Cl 266.7 1.000 0.0% 1 mL/L M-Cl 266.7 1.000 0.0% 2 mL/L M-Cl 262.5 0.984 1.6% Raw 266.7 0.5 mL/L M-Na 1 mL/L M-Na 2 mL/L M-Na 250 0.923 7.7% 4 mL/L M-Na 237.5 0.877 12.3% Raw 270.8 16 mL/L M-Na 120.8 0.426 57.4% 0.000 0.000 8 mL/L AL-Na 66.7 0.235 76.5% 0.000 0.000 Raw 283.3 16 mL/L M-Na (Acid/Base) 141.7 0.531 46.9% 0.000 0.000 Control 267.7 1.004 -0.4% 0.035 0.006 Simultaneous 112.5 0.422 57.8% 0.000 0.000 Raw 266.7 Sequence 1 108.3 0.377 62.3% 0.141 0.020 Sequence 2 114.6 0.399 60.1% 0.071 0.010 Raw 287.5

48

Table A-2. Dissolved organic carbon and total nitrogen results for preliminary experimental work

Dissolved Organic Carbon Total Nitrogen

Experiment Conc.

(mg/L C) C/Co % Rem. St. Dev. St. Dev./Co Conc.

(mg/L C) C/Co % Rem. St. Dev. St.

Dev./Co 0.5 mL/L M-Cl 4.48 0.835 16.5% 0.069 0.013 0.259 0.879 12.1% 0.000 0.000 1 mL/L M-Cl 3.86 0.719 28.1% 0.153 0.028 0.233 0.791 20.9% 0.000 0.000 2 mL/L M-Cl 2.52 0.469 53.1% 0.144 0.027 0.208 0.707 29.3% 0.020 0.044 Raw 5.37 0.294 0.5 mL/L M-Na 5.69 0.962 3.8% 0.311 1.087 -8.7% 1 mL/L M-Na 5.59 0.945 5.5% 0.301 1.052 -5.2% Raw 5.92 0.286 2 mL/L M-Na 5.63 0.935 6.5% 0.415 0.069 0.300 1.012 -1.2% 0.010 0.033 4 mL/L M-Na 5.45 0.906 9.4% 0.560 0.093 0.305 1.013 -1.3% 0.004 0.012 Raw 6.02 0.144 0.304 0.025 16 mL/L M-Na 5.40 0.933 6.7% 0.201 0.035 0.328 0.992 0.8% 0.015 0.045 8 mL/L Amberlite-Na 5.92 1.023 -2.3% 0.067 0.012 0.216 0.653 34.7% 0.004 0.013 Raw 5.79 0.330 16 mL/L M-Na (Acid/Base) 5.37 0.920 8.0% 0.153 0.026 0.362 0.997 0.3% 0.045 0.125 Control 5.94 1.018 -1.8% 0.109 0.019 0.367 1.011 -1.1% 0.032 0.089 Simultaneous 2.30 0.395 60.5% 0.303 0.052 0.341 0.939 6.1% 0.086 0.238 Raw 5.83 0.363 Sequence 1 2.02 0.362 63.8% 0.107 0.019 0.235 0.782 21.8% 0.017 0.058 Sequence 1 Midpoint (M-Cl) 2.21 0.395 60.5% 0.241 0.803 19.7% Sequence 2 2.11 0.378 62.2% 0.126 0.023 0.233 0.775 22.5% 0.013 0.044 Sequence 2 Midpoint (M-Na) 4.83 0.865 13.5% 0.322 1.073 -7.3% Raw 5.58 0.300

49

Table A-3. UV254 and SUVA results for preliminary experimental work UV254

Experiment Conc. C/Co % Rem. St. Dev. St. Dev./Co SUVA 0.5 mL/L M-Cl 0.144 0.776 22.4% 0.004 0.019 3.2 1 mL/L M-Cl 0.118 0.638 36.2% 0.004 0.023 3.1 2 mL/L M-Cl 0.074 0.397 60.3% 0.002 0.011 2.9 Raw 0.185 3.4 0.5 mL/L M-Na 0.181 1.040 -4.0% 1 mL/L M-Na 0.176 1.011 -1.1% 2 mL/L M-Na 0.178 0.989 1.1% 0.01 0.041 3.2 4 mL/L M-Na 0.176 0.978 2.2% 0.01 0.082 3.2 Raw 0.180 0.01 3.0 16 mL/L M-Na 0.147 0.840 16.0% 0.000 0.000 2.7 8 mL/L AL-Na 0.177 1.011 -1.1% 0.001 0.008 3.0 Raw 0.175 3.0 16 mL/L M-Na (Acid/Base) 0.145 0.843 15.7% 0.000 0.000 2.7 Control 0.174 1.009 -0.9% 0.001 0.004 2.9 Simultaneous 0.051 0.297 70.3% 0.007 0.041 2.2 Raw 0.172 2.9 Sequence 1 0.044 0.259 74.1% 0.001 0.014 2.2 Sequence 1 Midpoint (M-Cl) 0.051 0.304 69.6% 2.3 Sequence 2 0.144 0.256 74.4% 0.001 0.028 2.0 Sequence 2 Midpoint (M-Na) 0.139 0.827 17.3% 2.9 Raw 0.168 3.0

50

Table A-4. Chloride and sulfate results for preliminary experimental work Chloride Sulfate

Experiment Conc. (mg/L) C/Co % Rem. St. Dev. St. Dev./Co

Conc. (mg/L) C/Co % Rem. St. Dev. St. Dev./Co

0.5 mL/L M-Cl 19.99 1.49 -49.3% 0.321 0.024 16.76 1.25 -25.2% 0.395 0.000 1 mL/L M-Cl 24.50 1.83 -83.0% 0.728 0.054 9.67 0.72 27.7% 0.607 0.000 2 mL/L M-Cl 36.99 2.76 -176.3% 1.103 0.082 4.38 0.33 67.3% 0.125 0.000 Raw 13.39 22.89 0.5 mL/L M-Na 10.84 0.84 16.0% 14.43 0.65 35.2% 1 mL/L M-Na 11.66 0.90 9.6% 17.79 0.80 20.1% Raw 12.90 22.28 2 mL/L M-Na 13.22 0.97 2.8% 1.592 0.117 24.27 0.94 5.5% 6.815 0.265 4 mL/L M-Na 13.28 0.98 2.3% 1.943 0.143 23.99 0.93 6.6% 8.296 0.323 Raw 13.59 0.979 25.69 4.834 16 mL/L M-Na 14.85 1.09 -8.7% 0.687 0.050 26.37 0.96 3.8% 0.022 0.001 8 mL/L Amberlite-Na 13.84 1.01 -1.4% 0.020 0.001 27.71 1.01 -1.3% 0.071 0.003 Raw 13.66 27.39 16 mL/L M-Na (Acid/Base) 13.06 1.00 0.4% 0.193 21.237 21.24 0.97 3.5% 0.035 0.002 Simultaneous 38.53 2.94 -193.9% 0.701 0.053 6.59 0.30 70.1% 0.507 0.023 Control 13.17 1.00 -0.4% 0.018 0.001 22.02 1.00 -0.1% 0.068 0.003 Raw 13.11 22.00 Sequence 1 40.69 2.85 -184.8% 0.019 0.001 9.48 0.30 69.9% 0.058 0.002 Sequence 1 Midpoint (M-Cl) 40.97 2.87 -186.7% 10.14 Sequence 2 41.90 2.93 -193.2% 0.083 0.006 9.91 0.31 68.5% 0.030 0.001 Sequence 2 Midpoint (M-Na) 14.47 1.01 -1.3% 30.00 0.95 Raw 14.29 31.48

51

APPENDIX B HARDNESS RESULTS FOR EXPERIMENTAL WORK

Table B-1. Hardness removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na

Hardness

Experiment Conc.

(mg/L CaCO3) C/Co % Rem. St.

Dev. St.

Dev./Co Brine 95.8 0.34 66.2% 0.000 0.000 Acid/Base 136.5 0.48 51.8% 0.035 0.005 Raw 283.3 Brine Regen. 1x 126.0 0.47 52.7% 0.035 0.006 Acid/Base Regen. 1x 241.7 0.91 9.4% 0.000 0.000 Raw 266.7 Brine Regen. 2x 131.3 0.48 52.3% 0.071 0.011 Acid/Base Regen. 2x 255.2 0.93 7.2% 0.035 0.005 Raw 275.0

Table B-2. Hardness removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl

Hardness

Experiment Conc.

(mg/L CaCO3) C/Co % Rem. St. Dev. St. Dev./CoSimultaneous (Unregen. M-Cl) 116.7 0.41 58.8% 0.000 0.000 Raw 283.3 Simultaneous Regen 1x (Eq. Ratio = 10)

179.2 0.64 35.8% 0.000 0.000

Raw 279.2 Simultaneous Regen. 2x (Eq. Ratio = 25)

135.4 0.49 51.5% 0.071 0.011

Raw 279.2 Simultaneous Regen. 3x (Eq. Ratio = 25)

133.3 0.48 51.5% 0.000 0.000

Raw 275.0 Simultaneous Regen. 4x (Eq. Ratio = 25)

131.3 0.49 50.8% 0.071 0.011

Raw 266.7 2 mL/L M-Cl Regenerated 264.5 1.00 0.0% 0.000 0.000 Raw 264.5

52

Table B-3. Hardness removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl

Hardness

Experiment Conc.

(mg/L CaCO3) C/Co % Rem. St. Dev. St. Dev./Co Sequence 1 90.9 0.34 66.2% 0.000 0.000 Sequence 2 97.1 0.36 63.8% 0.071 0.011 Raw 268.6 Sequence 1 Regen. 1x 109.5 0.41 59.2% 0.071 0.011 Sequence 2 Regen. 1x 111.6 0.42 58.5% 0.000 0.000 Raw 268.6 Sequence 1 Regen. 2x 118.8 0.43 57.1% 0.035 0.005 Sequence 1 Midpoint (M-Cl) 272.7 0.99 1.5% 0.000 0.000 Sequence 2 Regen. 2x 121.9 0.44 56.0% 0.071 0.011 Sequence 2 Midpoint (M-Na) 119.8 0.43 56.7% 0.000 0.000 Raw 276.9 Sequence 1 Regen. 3x 115.7 0.43 56.9% 0.000 0.000 Sequence 1 Midpoint (M-Cl) 260.3 0.97 3.1% 0.000 0.000 Sequence 2 Regen. 3x 121.9 0.45 54.6% 0.071 0.011 Sequence 2 Midpoint (M-Na) 124.0 0.46 53.8% 0.000 0.000 Raw 268.6

Table B-4. Hardness removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl

Hardness

Experiment Conc.

(mg/L CaCO3) C/Co % Rem. St. Dev. St.

Dev./Co Simultaneous 73.3 0.27 73.1% 0.050 0.008 Raw 272.7 Simultaneous Regen. 1x 118.8 0.45 55.4% 0.035 0.005 Simultaneous (Eq. Ratio = 50) 83.7 0.31 68.6% 0.106 0.016 Raw 266.5 Simultaneous Regen. 2x 117.8 0.44 56.0% 0.000 0.000 Simultaneous (Regen. Time =60 min.) 117.8 0.44 56.0% 0.071 0.011 Raw 267.6 Simultaneous Regen. 3x 111.6 0.42 58.1% 0.000 0.000 Simultaneous (Regen. Time = 5 min.) 111.6 0.42 58.1% 0.000 0.000 Raw 266.5 Simultaneous Regen. 4x (Reused Regen. Solution) 149.8 0.56 44.2% 0.106 0.016

Raw 268.6

53

Table B-5. Hardness removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl with the reuse of a tap water regeneration solution (1 L singlet jar tests)

Hardness

Experiment Conc.

(mg/L CaCO3) C/Co % Rem. Tapwater Regen. 103.3 0.38 62.1% Tapwater Regen. 1x 148.8 0.55 45.5% Tapwater Regen. 2x 181.8 0.67 33.3% Tapwater Regen. 3x (added 2,563 mg/L Na2CO3) 146.7 0.54 46.2%

Raw 272.7 Regeneration Solution 785.1 Tapwater 148.8

Table B-6. Hardness removal over time for 16 mL/L MIEX-Na Hardness

Experiment Conc.

(mg/L CaCO3) C/Co % Rem. St. Dev. St. Dev./Co Mixing Time = 5 min. 110.4 0.40 60.4% 0.000 0.000 Mixing Time = 10 min. 109.4 0.39 60.8% 0.035 0.005 Mixing Time = 20 min. 104.2 0.37 62.7% 0.000 0.000 Mixing Time = 40 min. 108.3 0.39 61.2% 0.000 0.000 Raw 279.2

54

APPENDIX C DOC AND TN RESULTS FOR EXPERIMENTAL WORK

Table C-1. Organics removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na Dissolved Organic Carbon Total Nitrogen

Experiment Conc. C/Co % Rem. St. Dev. St. Dev./Co Conc. C/Co % Rem. St. Dev. St. Dev./Co Brine 4.92 0.92 8.5% 0.15 0.03 0.29 1.12 -12.0% 0.02 0.08 Acid/Base 4.94 0.92 8.2% 0.20 0.04 0.28 1.09 -9.0% 0.02 0.09 Raw 5.38 0.26 Brine Regen. 1x 4.77 0.88 12.2% 0.06 0.01 0.24 0.96 3.8% 0.01 0.02 Acid/Base Regen. 1x 5.00 0.92 7.9% 0.05 0.01 0.27 1.07 -6.7% 0.01 0.05 Raw 5.43 0.25 Brine Regen. 2x 4.64 0.84 16.1% 0.13 0.02 0.28 0.93 6.5% 0.01 0.04 Acid/Base Regen. 2x 4.87 0.88 11.8% 0.07 0.01 0.26 0.89 10.7% 0.01 0.02 Raw 5.53 0.29

55

Table C-2. Organics removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl Dissolved Organic Carbon Total Nitrogen

Experiment Conc. C/Co % Rem. St. Dev. St. Dev./Co Conc. C/Co % Rem. St. Dev. St. Dev./Co Simultaneous (Unregen. M-Cl) 2.65 0.49 51.1% 0.11 0.02 0.25 0.80 19.7% 0.02 0.07

Raw 5.41 0.31 Simultaneous Regen 1x (Eq. Ratio = 10)

3.49 0.59 40.6% 0.03 0.01 0.49 1.46 -45.5% 0.01 0.03

Raw 5.88 0.34 Simultaneous Regen. 2x (Eq. Ratio = 25)

1.57 0.27 73.4% 0.13 0.02 0.21 0.72 27.9% 0.02 0.06

Raw 5.92 0.30 Simultaneous Regen. 3x (Eq. Ratio = 25)

1.44 0.25 75.3% 0.05 0.01 0.20 0.62 37.9% 0.02 0.06

Raw 5.80 0.31 Simultaneous Regen. 4x (Eq. Ratio = 25)

1.59 0.27 72.8% 0.05 0.01 0.23 0.79 21.4% 0.01 0.04

Raw 5.85 0.29 2 mL/L M-Cl Regenerated 1.39 0.24 75.6% 0.13 0.02 0.19 0.70 30.2% 0.02 0.08

Raw 5.68 0.28

56

Table C-3. Organics removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl Dissolved Organic Carbon Total Nitrogen

Experiment Conc. C/Co % Rem. St. Dev. St. Dev./Co Conc. C/Co % Rem. St. Dev. St. Dev./CoSequence 1 1.87 0.35 65.0% 0.07 0.01 0.23 0.73 26.7% 0.01 0.02 Sequence 2 1.75 0.33 67.1% 0.14 0.03 0.23 0.71 28.8% 0.02 0.06 Raw 5.33 0.32 Sequence 1 Regen. 1x 1.69 0.30 70.0% 0.13 0.02 0.40 1.30 -29.7% 0.03 0.08 Sequence 2 Regen. 1x 1.43 0.26 74.5% 0.12 0.02 0.20 0.64 35.7% 0.02 0.05 Raw 5.61 0.31 Sequence 1 Regen. 2x 1.38 0.26 74.5% 0.06 0.01 0.24 0.79 21.0% 0.01 0.04 Sequence 1 Midpoint (M-Cl) 1.27 0.24 76.4% 0.00 0.00 0.22 0.71 28.5% 0.01 0.03 Sequence 2 Regen. 2x 1.63 0.30 69.8% 0.31 0.06 0.19 0.62 38.0% 0.01 0.03 Sequence 2 Midpoint (M-Na) 4.70 0.87 13.0% 0.00 0.00 0.35 1.15 -15.4% 0.01 0.02 Raw 5.40 0.30 Sequence 1 Regen. 3x 1.31 0.22 77.7% 0.13 0.02 0.19 0.67 33.0% 0.01 0.04 Sequence 1 Midpoint (M-Cl) 1.41 0.24 75.9% 0.20 0.03 0.19 0.67 33.0% 0.01 0.02 Sequence 2 Regen. 3x 1.32 0.23 77.4% 0.19 0.03 0.19 0.70 30.3% 0.01 0.02 Sequence 2 Midpoint (M-Na) 4.73 0.81 19.2% 0.00 0.00 0.35 1.27 -26.9% 0.00 0.00 Raw 5.85 0.28

57

Table C-4. Organics removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl Dissolved Organic Carbon Total Nitrogen

Experiment Conc. C/Co % Rem. St. Dev. St. Dev./Co Conc. C/Co % Rem. St. Dev. St. Dev./Co Simultaneous 2.42 0.43 57.1% 0.15 0.03 0.23 0.69 30.8% 0.03 0.08 Raw 5.65 0.34 Simultaneous Regen. 1x 2.03 0.35 64.6% 0.11 0.02 0.22 0.71 29.3% 0.03 0.09 Simultaneous (Eq. Ratio = 50) 1.80 0.31 68.6% 0.04 0.01 0.20 0.64 36.4% 0.01 0.03

Raw 5.73 0.32 Simultaneous Regen. 2x 1.90 0.34 65.8% 0.10 0.02 0.24 0.75 25.0% 0.01 0.04 Simultaneous (Regen. Time =60 min.) 1.66 0.30 70.2% 0.20 0.04 0.23 0.70 29.8% 0.02 0.05

Raw 5.57 0.32 Simultaneous Regen. 3x 1.70 0.29 70.7% 0.07 0.01 0.23 0.71 28.9% 0.02 0.07 Simultaneous (Regen. Time = 5 min.) 1.85 0.32 68.2% 0.22 0.04 0.22 0.65 34.5% 0.01 0.04

Raw 5.80 0.33 Simultaneous Regen. 4x (Reused Regen. Solution) 1.52 0.28 72.1% 0.13 0.02 0.23 0.77 23.0% 0.03 0.11

Raw 5.43 0.29

58

APPENDIX D UV254 AND SUVA RESULTS FOR EXPERIMENTAL WORK

Table D-1. UV254 removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na

UV254

Experiment Conc. (cm-1) C/Co%

Rem. St. Dev. St. Dev./Co SUVA Brine 0.149 0.87 12.6% 0.001 0.004 3.0 Acid/Base 0.147 0.86 13.5% 0.000 0.000 3.0 Raw 0.170 3.2 Brine Regen. 1x 0.137 0.80 20.2% 0.001 0.004 2.9 Acid/Base Regen. 1x 0.143 0.83 16.7% 0.001 0.004 2.8 Raw 0.171 3.1 Brine Regen. 2x 0.135 0.80 20.1% 0.000 0.000 2.9 Acid/Base Regen. 2x 0.143 0.85 15.4% 0.000 0.000 2.9 Raw 0.169 3.1

Table D-2. UV254 removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl

UV254 Experiment Conc. (cm-1) C/Co % Rem. St. Dev. St. Dev./Co SUVA

Simultaneous (Unregen. M-Cl) 0.070 0.412 58.8% 0.001 0.008 2.7

Raw 0.170 3.1 Simultaneous Regen 1x (Eq. Ratio = 10)

0.028 0.165 83.5% 0.000 0.000 0.8

Raw 0.170 2.9 Simultaneous Regen. 2x (Eq. Ratio = 25)

0.023 0.131 86.9% 0.001 0.004 1.4

Raw 0.172 2.9 Simultaneous Regen. 3x (Eq. Ratio = 25)

0.021 0.124 87.6% 0.000 0.000 1.5

Raw 0.170 2.9 Simultaneous Regen. 4x (Eq. Ratio = 25)

0.021 0.124 87.6% 0.001 0.008 1.3

Raw 0.170 2.9 2 mL/L M-Cl Regenerated 0.022 0.126 87.4% 0.001 0.004 1.5 Raw 0.170 3.0

59

Table D-3. UV254 removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl

UV254

Experiment Conc. (cm-1) C/Co

% Rem. St. Dev. St. Dev./Co SUVA

Sequence 1 0.038 0.22 77.9% 0.001 0.004 2.0 Sequence 2 0.033 0.19 80.6% 0.001 0.008 1.9 Raw 0.170 3.2 Sequence 1 Regen. 1x 0.030 0.18 82.4% 0.000 0.000 1.8 Sequence 2 Regen. 1x 0.023 0.13 86.8% 0.001 0.004 1.6 Raw 0.170 3.0 Sequence 1 Regen. 2x 0.025 0.14 85.6% 0.002 0.012 1.8 Sequence 1 Midpoint (M-Cl) 0.021 0.12 87.6% 0.000 0.000 1.6 Sequence 2 Regen. 2x 0.022 0.13 87.1% 0.001 0.008 1.4 Sequence 2 Midpoint (M-Na) 0.137 0.81 19.4% 0.000 0.000 2.9 Raw 0.170 3.1 Sequence 1 Regen. 3x 0.021 0.12 87.6% 0.000 0.000 1.6 Sequence 1 Midpoint (M-Cl) 0.019 0.11 88.8% 0.000 0.000 1.3 Sequence 2 Regen. 3x 0.019 0.11 88.8% 0.000 0.000 1.4 Sequence 2 Midpoint (M-Na) 0.133 0.79 21.3% 0.000 0.000 2.8 Raw 0.169 2.9

Table D-4. UV254 removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl

UV254

Experiment Conc. (cm-1) C/Co % Rem. St. Dev. St. Dev./Co SUVA

Simultaneous 0.056 0.33 67.2% 0.00 0.00 2.3 Raw 0.169 3.0 Simultaneous Regen. 1x 0.038 0.22 78.3% 0.00 0.01 1.9 Simultaneous (Eq. Ratio = 50) 0.038 0.22 78.0% 0.00 0.02 2.1 Raw 0.173 3.0 Simultaneous Regen. 2x 0.031 0.18 82.2% 0.00 0.00 1.6 Simultaneous ( Regen. Time =60 min.) 0.030 0.17 82.7% 0.00 0.01 1.8

Raw 0.171 3.1 Simultaneous Regen. 3x 0.029 0.17 83.0% 0.00 0.00 1.7 Simultaneous (Regen. Time = 5 min.) 0.030 0.17 82.7% 0.00 0.00 1.6

Raw 0.171 2.9 Simultaneous Regen. 4x (Reused Regen. Solution) 0.024 0.14 86.3% 0.00 0.00 1.6

Raw 0.172 3.2

60

Table D-5. UV removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl with the reuse of a tap water regeneration solution (1 L singlet jar tests)

Hardness Experiment Conc. (cm-1) C/Co % Rem.

Tapwater Regen. 0.026 0.15 84.9% Tapwater Regen. 1x 0.025 0.15 85.5% Tapwater Regen. 2x 0.022 0.13 87.2% Tapwater Regen. 3x (added 2,563 mg/L Na2CO3) 0.023 0.13 86.6%

Raw 0.172 Regeneration Solution 2.689

61

APPENDIX E CHLORIDE AND SULFATE RESULTS FOR EXPERIMENTAL WORK

Table E-1. Chloride addition and sulfate removal comparison of brine and acid/base regeneration for 16 mL/L MIEX-Na Chloride Sulfate

Experiment Conc. (mg/L) C/Co

% Rem.

St. Dev. St. Dev./Co

Conc. (mg/L) C/Co

% Rem.

St. Dev. St. Dev./Co

Brine 17.19 1.39 -39.3% 0.16 0.01 25.66 0.98 2.2% 0.10 0.00 Acid/Base 12.52 1.01 -1.4% 0.15 0.01 26.42 1.01 -0.6% 0.31 0.01 Raw 12.34 26.25 Brine Regen. 1x 13.11 1.25 -24.8% 0.56 0.05 16.32 0.97 3.2% 0.14 0.01 Acid/Base Regen. 1x 10.85 1.03 -3.3% 0.00 0.00 17.12 1.02 -1.5% 0.03 0.00 Raw 10.50 16.86 Brine Regen. 2x 12.83 1.14 -13.6% 0.16 0.01 22.53 0.98 2.0% 0.04 0.00 Acid/Base Regen. 2x 11.69 1.04 -3.5% 0.02 0.00 23.58 1.03 -2.6% 0.02 0.00 Raw 11.29 22.99

62

Table E-2. Chloride addition and sulfate removal of simultaneous treatment using 16 mL/L MIEX-Na and (unregenerated) 2 mL/L MIEX-Cl and a dose of 2 mL/L regenerated MIEX-Cl Chloride Sulfate

Experiment Conc. (mg/L) C/Co % Rem.

St. Dev. St. Dev./Co

Conc. (mg/L) C/Co % Rem.

St. Dev. St. Dev./Co

Simultaneous (Unregen. M-Cl) 43.64 3.87 -286.7% 0.71 0.06 6.31 0.28 72.1% 0.29 0.01

Raw 11.28 22.61 Simultaneous Regen 1x (Eq. Ratio = 10)

37.71 3.35 -234.9% 0.20 0.02 4.82 0.21 78.8% 0.02 0.00

Raw 11.26 22.69 Simultaneous Regen. 2x (Eq. Ratio = 25)

43.83 3.86 -286.5% 1.94 0.17 4.32 0.19 81.0% 0.17 0.01

Raw 11.34 22.67 Simultaneous Regen. 3x (Eq. Ratio = 25)

44.61 4.10 -310.3% 0.43 0.04 3.22 0.17 83.2% 0.09 0.00

Raw 10.87 19.19 Simultaneous Regen. 4x (Eq. Ratio = 25)

40.24 3.73 -273.0% 0.11 0.01 2.83 0.16 84.3% 0.00 0.00

Raw 10.79 18.00 2 mL/L M-Cl Regenerated 41.70 3.68 -267.8% 0.34 0.03 2.72 0.15 84.8% 0.10 0.01

Raw 11.34 17.94

63

Table E-3. Chloride addition and sulfate removal for sequential treatments using 16 mL/L MIEX-Na and (regenerated) 2 mL/L MIEX-Cl

Chloride Sulfate

Experiment Conc. (mg/L) C/Co % Rem. St. Dev. St. Dev./Co

Conc. (mg/L) C/Co % Rem. St. Dev. St. Dev./Co

Sequence 1 41.35 3.61 -261.4% 0.45 0.04 2.86 0.16 83.7% 0.14 0.01 Sequence 2 43.13 3.77 -276.9% 0.36 0.03 3.02 0.17 82.7% 0.01 0.00 Raw 11.44 17.52 Sequence 1 Regen. 1x 45.25 3.86 -286.2% 0.03 0.00 3.07 0.17 82.9% 0.01 0.00 Sequence 2 Regen. 1x 45.23 3.86 -286.0% 0.02 0.00 3.03 0.17 83.1% 0.05 0.00 Raw 11.72 17.98 Sequence 1 Regen. 2x 46.37 3.90 -289.7% 0.23 0.02 2.92 0.16 83.9% 0.02 0.00 Sequence 1 Midpoint (M-Cl) 0.00 3.40 -240.4% 0.00 0.00 0.00 0.19 80.9% 0.00 0.00

Sequence 2 Regen. 2x 44.44 3.73 -273.5% 0.49 0.04 3.06 0.17 83.2% 0.04 0.00 Sequence 2 Midpoint (M-Na) 0.00 1.23 -22.6% 0.00 0.00 0.00 0.92 7.5% 0.00 0.00

Raw 11.90 18.16 Sequence 1 Regen. 3x 46.13 3.78 -277.6% 0.55 0.05 2.92 0.15 84.6% 0.03 0.00 Sequence 1 Midpoint (M-Cl) 36.29 3.25 -224.7% 0.00 0.00 3.14 0.18 82.1% 0.00 0.00

Sequence 2 Regen. 3x 50.62 4.14 -314.4% 0.41 0.03 3.46 0.18 81.8% 0.03 0.00 Sequence 2 Midpoint (M-Na) 19.68 1.76 -76.2% 0.00 0.00 16.29 0.93 7.4% 0.00 0.00

Raw 12.22 19.00

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Table E-4. Chloride addition and sulfate removal for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L (regenerated) MIEX-Cl

Chloride Sulfate

Experiment Conc. (mg/L) C/Co % Rem.

St. Dev. St. Dev./Co

Conc. (mg/L) C/Co % Rem.

St. Dev. St. Dev./Co

Simultaneous 43.07 3.85 285.4% 0.19 0.03 4.07 0.23 76.6% 0.00 0.00 Raw 11.17 17.53 Simultaneous Regen. 1x 46.94 4.15 314.8% 3.06 0.27 3.44 0.19 80.8% 0.18 0.01 Simultaneous (Eq. Ratio = 50) 55.82 4.93 393.3% 3.00 0.27 3.67 0.21 79.4% 0.07 0.00

Raw 11.32 17.85 Simultaneous Regen. 2x 47.57 4.24 324.0% 0.24 0.02 3.06 0.17 82.6% 0.02 0.00 Simultaneous (Regen. Time =60 min.) 48.44 4.32 331.8% 0.51 0.05 3.02 0.17 82.8% 0.04 0.00

Raw 11.22 17.57 Simultaneous Regen. 3x 48.79 4.33 333.3% 0.03 0.00 3.11 0.18 82.3% 0.00 0.00 Simultaneous (Regen. Time = 5 min.) 43.94 3.90 -290.2% 0.08 0.01 3.09 0.18 82.4% 0.04 0.00

Raw 11.26 17.60 Simultaneous Regen. 4x (Reused Regen. Solution) 45.20 3.99 299.3% 0.73 0.06 3.06 0.17 82.7% 0.06 0.00

Raw 11.32 17.70

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APPENDIX F EEMS FOR SELECTED EXPERIMENTAL WORK

Figure F-1. EEMs for (left) raw water and (right) 2 mL/L unregenerated MIEX-Cl treated water.

Figure F-2. EEMs for (left) raw water, (center) 16 mL/L MIEX-Na treated water, and (right) 8 mL/L Amberlite-Na treated water.

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Figure F-3. EEMs for (left) raw water and simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L unregenerated MIEX-Cl.

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Figure F-4. EEMs for (top left) raw water for (top right) simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L unregenerated MIEX-Cl and the (bottom left) raw water for (bottom right) 16 mL/L MIEX-Na and 2 mL/L MIEX-Cl that had been through four regeneration cycles.

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Figure F-5. EEMs for (left) raw water, (center) 16 mL/L MIEX-Na treated water, and (right) 2 mL/L MIEX-Cl treated water with resin that had been through two regeneration cycles.

Figure F-6. EEMs for (left) raw water (right) for simultaneous treatment using 16 mL/L MIEX-Na and 2 mL/L MIEX-Cl that had been through two regeneration cycles.

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BIOGRAPHICAL SKETCH

Jennifer Nicole Apell was born in1985 in Tampa, Florida. She lived in the Tampa

Bay area until her acceptance to the University of Florida and subsequent relocation to

Gainesville. She graduated with her B.S. in environmental engineering sciences in

December 2008. She earned the honors of summa cum laude with her honors thesis A

Critical Review of Low-Pressure Membrane Fouling by Natural Organic Matter. As a

participant of the 4/1 program, she immediately started work on a Master of Engineering

in environmental engineering. Her focus was on water and wastewater treatment which

was complimented by her thesis research on ion exchange for water treatment. She has

since accepted a position with the engineering consulting firm CDM, Inc. at its

headquarters in Cambridge, MA.