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1
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
2
© 2009 Jennifer Nicole Apell
3
To Dr. Treavor H. Boyer
4
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.
5
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
7
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
9
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
12
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.
13
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.
14
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
15
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
16
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.
17
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
18
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.
19
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
Figure 3
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38
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39
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40
and sequeOC, and (cEX-Cl resin
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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)
(b)
(c)
Figure 3
Figure 3
0%
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20%
30%
40%
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43
MIEX-Na re
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me = x-axis on Time = 30
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44
resin utiliza
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io
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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.
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