United States ,
Environmental Protection
Agency
Office of Research and \
Development j
Washington, DC 20460'
EPA/600/R-00/063
June 2000
http://www.epa.gov
Arsenic Removal from
Drinking Water by
Coagulation/Filtration and
Lime Softening Plants
0
As (III)
As(V)
fe-
fc
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EPA/600/R-00/063
June 2000
Arsenic Removal from Drinking Water
by Coagulation/Filtration
and Lime Softening Plants
by
Keith A. Fields
Abraham Chen
Lili Wang
Battelle
Columbus, OH 43201-2693
Contract No. 68-C7-0008
Work Assignment 2-09
for
Work Assignment Manager
Thomas J. Sorg
Water Supply and Water Resources Division
National Risk Management Research Laboratory
Cincinnati, OH 45268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
o
Printed on Recycled Paper
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Disclaimer
The information in this document has been funded by the United States Environ-
mental Protection Agency (EPA) under Work Assignment (WA) 2-09 of Contract No.
68-C7-0008 to Battelle. It has been subjected to the Agency's peer and administra-
tive reviews and has been approved for publication as an EPA document. Mention of
trade names or commercial products does not constitute an endorsement or recom-
mendation for use.
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Foreword
The United States Environmental Protection Agency is charged by Congress with
protecting the Nation's land, air, and water resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement action leading to
a compatible balance between human activities and the ability of natural systems to
support and nurture life. To meet this mandate, EPA's research program is providing
data and technical support for solving environmental problems today and building a
science knowledge base necessary to manage our ecological resources wisely, under-
stand how pollutants affect our health, and prevent or reduce environmental risks in
the future.
The National Risk Management Research Laboratory is the Agency's center for inves-
tigation of technological and management approaches for reducing risks from threats
to human health and the environment. The focus of the Laboratory's research pro-
gram is on methods for prevention and control of pollution to air, land, water, and sub-
surface resources: protection of water quality in public water systems; remediation of
contaminated sites and ground water; and prevention and control of indoor air. The
goal of this research effort is to evaluate the performance on a full-scale level of five
processes, including coagulation/filtration, lime softening, iron oxidation/filtration, ion
exchange, and activated alumina, to consistently remove arsenic over a sustained
period of time (1 year).
This publication has been produced as part of the Laboratory's strategic long-term
research plan. It is published and made available by EPA's Office of Research and
Development to assist the user community and to link researchers with their clients.
E. Timothy Oppelt, Director
National Risk Management Research Laboratory
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Abstract
This report documents treatment plant information as well as results of sampling and
analysis at two coagulation/filtration plants (referred to in this document as Plants A
and B) and one lime softening plant (referred to as Plant C). The objective of sam-
pling and analysis was to evaluate the effectiveness of the water treatment plants to
consistently remove arsenic (As) from source water. Additionally, data were collected
in this study to evaluate the characteristics of the residuals produced by the treatment
processes.
The study was divided into three phases: source water sampling, preliminary sam-
pling, and long-term evaluation. The first phase, source water sampling, was con-
ducted to evaluate source water characteristics at each plant. The second phase,
preliminary sampling, consisted of a four-week sampling period to refine procedures
prior to implementing the long-term evaluation phase. The third phase, long-term
evaluation, consisted of weekly sample collection and analysis for approximately
1 year. Sludge samples also were collected at each facility during a single sampling
event from settling lagoons/ponds during a two-month period. Samples of recycle
supernatant water (Plant A) and supernatant discharge water (Plants B and C) were
collected monthly beginning in November 1998 and continuing until June 1999.
Long-term evaluation of Plants A and B demonstrated that conventional coagula-
tion/filtration can consistently achieve low levels of arsenic in the treated water (i.e.,
less than 5 ug/L). The total arsenic concentrations at Plant A were reduced by an
average of 52%, which represents a decrease of average arsenic concentrations
from 7.5 ug/L in the source water to 3.5 ug/L in the finished water. Average total arse-
nic removal efficiency at Plant B was 79%, with an average source water concentra-
tion of 19.1 ug/L and an average finished water concentration of 4.0 ug/L. Adsorption
and coprecipitation of As(V) with iron and aluminum floes are believed to have been
the primary arsenic removal mechanisms at these plants.
The lime softening facility, Plant C, was not able to consistently reduce arsenic to low
levels in treated water. The average total arsenic concentration in Plant C source
water was 32.0 ug/L, and the lime softening plant reduced the average total arsenic
concentration to 16.6 ug/L in the finished water, which equals a 45% removal effi-
ciency. As(lll) was the primary species of soluble arsenic in the raw water and was
almost completely oxidized to As(V) as a result of two chlorination steps that occurred
prior to softening and prior to filtration. The primary mechanism of arsenic removal
was likely adsorption and coprecipitation of As(V) with iron that was present in the
source water. Plant C operated at a pH of 9.6, a level at which arsenic removal by
coprecipitation with calcium carbonate is reported to be less than 10% (Sorg and
Logsdon, 1978; McNeill and Edwards, 1997b).
None of the sludge samples collected at Plants A, B, and C qualified as a hazardous
waste based on Toxicity Characteristic Leaching Procedure (TCLP) testing for metals.
Therefore, nonhazardous waste landfills should be able to accept the sludge gener-
ated by these treatment processes.
IV
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Contents
Foreword iii
Abstract iv
Appendices vi
Figures vii
Tables viii
Acronyms and Abbreviations x
1.0 Introduction 1
1.1 Background 1
1.1.1 General Chemistry of Arsenic 1
1.1.2 Determination of Arsenic Species '. 3
1.1.3 Treatment Technologies for Arsenic Removal 3
1.1.3.1 Coagulation/Filtration : 3
1.1.3.2 Lime Softening 4
1.1.4 Data Gaps 5
1.2 Objectives 5
1.3 Report Organization 5
2.0 Conclusions 6
3.0 Materials and Methods 7
3.1 General Project Approach 7
3.2 Preparation of Sampling Kits and Sample Coolers 8
3.2.1 Preparation of Arsenic Speciation Kits 8
3.2.2 Preparation of Recycle Backwash Water/Supernatant
Discharge Sampling Kits 9
3.2.3 Preparation of Sample Coolers 9
3.3 Sampling Procedures 10
3.3.1 General Approach and Sampling Schedules 10
3.3.2 Arsenic Field Speciation Procedure 10
3.3.3 Recycle Supernatant Water/Supernatant Discharge Sampling
Procedure 13
3.3.4 Sampling Procedure for Other Water Quality Parameters 13
3.4 Analytical Procedures 13
4.0 Results and Discussion 17
4.1 Plant Selection 17
4.2 Plant A 17
4.2.1 Plant A Description 18
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4.2.2 Initial Source Water Sampling 18
4.2.3 Preliminary Sampling 19
4.2.4 Long-Term Sampling 22
4.2.4.1 Arsenic 22
4.2.4.2 Other Water Quality Parameters 24
4.2.4.3 Recycle Supernatant Water 26
4.2.4.4 Sludge 27
4.3 Plant B 28
4.3.1 Plant B Description 29
4.3.2 Initial Source Water Sampling 29
4.3.3 Preliminary Sampling 30
4.3.4 Long-Term Sampling 33
4.3.4.1 Arsenic 33
4.3.4.2 Other Water Quality Parameters 35
4.3.4.3 Supernatant Discharge Water 38
4.3.4.4 Sludge 38
4.4 Plant C 39
4.4.1 Plant C Description 39
4.4.2 Initial Source Water Sampling 40
4.4.3 Preliminary Sampling 41
4.4.4 Long-Term Sampling 44
4.4.4.1 Arsenic 44
4.4.4.2 Other Water Quality Parameters 46
4.4.4.3 Supernatant Discharge Water 49
4.4.4.4 Sludge 49
5.0 Quality Assurance/Quality Control 51
5.1 Quality Assurance Objectives 51
5.2 Overall Assessment of Data Quality 51
5.2.1 Total Arsenic, Aluminum, Iron, and Manganese 51
5.2.2 Water Quality Parameters 52
5.2.3 TCLP Metals in Sludge 52
6.0 References 53
Appendices
Appendix A. Complete Analytical Results from Long-Term Sampling at
Plant A 55
Appendix B. Complete Analytical Results from Long-Term Sampling at
Plant B 69
Appendix C. Complete Analytical Results from Long-Term Sampling at
Plant C , 83
VI
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Figures
Page
Figure 1 -1. Solubility Diagrams for As(III) and As(V) 2
Figure 3-1. Example of Sample Bottle Label 10
Figure 3-2. Photographs of a Typical Sample Cooler (with Three Sample
Compartments) and a Color-Coded Instruction Sheet 11
Figure 3-3. Instruction Sheet for Arsenic Field Speciation 14
Figure 3-4. Instruction Sheet for Recycle Supernatant Water/Supernatant
Discharge Sampling 15
Figure 4-1. Schematic Diagram of Plant A Treatment Process 18
Figure 4-2. Process Flow Diagram and Sampling Locations at Plant A 20
Figure 4-3. Total Arsenic Analytical Results During Long-Term Sampling at
Plant A 24
Figure 4-4. Arsenic Form and Species Analytical Results During Long-Term
Sampling at Plant A 25
Figure 4-5. Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at
Plant A ! 27
Figure 4-6. Schematic Diagram, Plant B 29
Figure 4-7. Process Flow Diagrams and Sampling Locations at Plant B 31
Figure 4-8. Total Arsenic Analytical Results During Long-Term Sampling at
PlantB 35
Figure 4-9. Arsenic Form and Species Analytical Results During Long-Term
Sampling at Plant B '. 36
Figure 4-10. Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at
PlantB 38
Figure 4-11. Schematic Diagram, Plant C 40
Figure 4-12. Process Flow Diagram and Sampling Locations at Plant C 42
Figure 4-13. Total Arsenic Analytical Results during Long-Term Sampling at
Plant C 46
Figure 4-14. Arsenic Form and Species Analytical Results During Long-Term
Sampling at Plant C 47
Figure 4-15. Inlet Turbidity, pH, Hardness, and Alkalinity Analytical Results at
Plant C 49
VII
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Tables
Page
Table 3-1. Sample Containers and Preservation Methods 9
Table 3-2. Summary of Sampling Activities at Plants A, B, and C 12
Table 3-3. Summary of Sampling Schedule for Plants A and B 12
Table 3-4. Summary of Sampling Schedule for Plant C 13
Table 3-5. Summary of Analytical Methods for Arsenic Treatment Study 16
Table 4-1. Initial List of Treatment Facilities Identified for the Study 17
Table 4-2. Source Water Analytical Results at Plant A (February 3,1998) 19
Table 4-3. Analytical Results from Preliminary Sampling at Plant A
(April 9,1998 through April 30,1998) 21
Table 4-4. Summary of Arsenic Analytical Results at Plant A (June 1998-
June1999) 23
Table 4-5. Summary of Water Quality Parameter Analytical Results at Plant A
(June 1998-June 1999) 26
Table 4-6. Summary of Analytical Results from Recycle Backwash Water
Samples at Plant A (November 11, 1998-June 16, 1999). 27
Table 4-7. Previous Analytical Results of Sludge Sampling at Plant A (1996-
1997) 28
Table 4-8. Analytical Results of Sludge Sampling at Plant A
(December 2,1998) 28
Table 4-9. Source Water Analytical Results at Plant B (February 5,1998) 30
Table 4-10. Analytical Results from Preliminary Sampling at Plant B (April 23,
1998 through May 14,1998) 32
Table 4-11. Summary of Arsenic Analytical Results at Plant B (June 1998-
June1999) 34
Table 4-12. Summary of Water Quality Parameter Analytical Results at Plant B
(June 1998-June 1999) 37
Table 4-13. Summary of Analytical Results from Supernatant Discharge Water
Samples at Plant B (November 12,1998-June 17, 1999) 39
Table 4-14. Analytical Results of Sludge Sampling at Plant B
(December 15, 1998) 39
Table 4-15. Arsenic Concentrations in Ground Water Wells at Plant C (1992) 40
Table 4-16. Source Water Sampling Analytical Results at Plant C
(February 27,1998) 41
Table 4-17. Analytical Results from Preliminary Sampling at Plant C (April 27,
1998 through May 18, 1998) 43
Table 4-18. Summary of Arsenic Analytical Results at Plant C (June 1998-
June 1999) 45
VIII
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Table 4-19. Summary of Water Quality Parameter Analytical Results at Plant C
(June 1998-June 1999) 48
Table 4-20. Summary of Analytical Results from Supernatant Discharge Water
Samples at Plant C (November 9,1998-June 14, 1999) 50
Table 4-21. Analytical Results of Sludge Sampling at Plant C
(November 16,1998) .; 50
IX
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Acronyms and Abbreviations
AF after-filtration sampling location
AWWA American Water Works Association
Dl distilled
EDR electrodialysis reversal
EPA United States Environmental Protection Agency
GFAAS graphite-furnace atomic-absorption spectrophotometer
Gl gastrointestinal
gpm gallons per minute
HOPE high-density polyethylene
ICP-MS inductively coupled plasma-mass spectrometry
ID identification
IN inlet sampling location
MCL maximum contaminant level
MDL method detection limit
mgd million gallons per day
MS matrix spike
MSD matrix spike duplicate
ND not detected
MOM natural organic matter
NTU nephelometric turbidity units
PAC powdered activated carbon
PAX-18 liquid polyaluminum chloride
PF before filtration (prefiltration) sampling location
POC point of contact
QA quality assurance
QAPP Quality Assurance Project Plan
QA/QC Quality Assurance/Quality Control
RPD relative percent difference
SDWA Safe Drinking Water Act
STLC soluble threshold limit concentration
TCLP Toxicity Characteristic Leaching Procedure
TDS total dissolved solids
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TOC
TSS
WA
WAM
%R
total organic carbon
total suspended solids
work assignment
work assignment manager
percent recovery
XI
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Acknowledgments
Sincere appreciation is extended to the three water treatment facilities that partici-
pated in this study. The staff from each facility contributed greatly to this project by
collecting samples every week for more than 12 months. The success of this study
depended on the personnel of these plants, and all performed exceptionally well.
Their work on this project was uncompensated, making their superb efforts even
more remarkable. Personnel from all plants are thanked for their hard work and
dedication throughout the duration of this project.
XII
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. Introduction
This project consisted, in part, of a field study to collect
samples from various locations throughout the treatment
processes at two coagulation/filtration plants and one
lime softening plant. These samples were analyzed and
used to evaluate the effectiveness of conventional coag-
ulation/filtration and lime softening processes to consist-
ently reduce arsenic (As) in source water to low levels.
This project also includes the collection of process resid-
ual samples that were used to determine the quantity
and chemical characteristics of the residuals produced
by these treatment processes. This report describes the
design and operation of the three treatment plants and
presents the results of the analyses of the water samples
collected from the plants during one year of operation.
1.1 Background
The Safe Drinking Water Act (SDWA) of 1994 mandates
that the United States Environmental Protection Agency
(EPA) identify and regulate drinking water contaminants
that may have an adverse human health effect and that
are known or anticipated to occur in public water supply
systems. Arsenic is a naturally occurring contaminant
that has known adverse human health effects. Excessive
amounts of arsenic can cause acute gastrointestinal (Gl)
and cardiac damage. Chronic doses can cause vascular
disorders such as blackfoot disease (Chen, S.L., et al.,
1994), and epidemiological studies have linked arsenic
to skin and lung cancer (Tate and Arnold, 1990). In
1975, under the SDWA, EPA established a maximum
contaminant level (MCL) for arsenic at 0.05 mg/L. Since
that time, revision of the MCL has been considered a
number of times, but no change has been made. The
SDWA was amended in 1996 and these amendments
required that the EPA develop an arsenic research strat-
egy and publish a proposal to revise the arsenic MCL by
January 2000.
A draft arsenic research plan was prepared by the EPA
in December 1996 and was finalized in February 1998
based upon a technical review by the EPA's Board of
Scientific Counselors (EPA, 1998). The plan identifies
the research needed by the EPA to support a proposed
revision of the arsenic MCL. The plan also identifies a
number of treatment methods available for arsenic re-
moval and recognizes the need to determine the capabil-
ity of these technologies to reduce arsenic to a level
significantly lower than the current MCL. This study was
conducted as part of the EPA's arsenic research strat-
egy to determine the ability of conventional water treat-
ment processes to consistently remove arsenic from
drinking water.
1.1.1 General Chemistry of Arsenic
Arsenic is a common, naturally occurring drinking water
contaminant that originates from arsenic-containing rocks
and soil and is transported to natural waters through ero-
sion and dissolution. Arsenic occurs in natural waters in
both organic and inorganic forms. However, inorganic
arsenic is predominant in natural waters and is the most
likely form of arsenic to exist at concentrations that cause
regulatory concern (Edwards et al., 1998).
The valence and species of inorganic arsenic are de-
pendent on the oxidation-reduction conditions and the
pH of the water. As a general rule of thumb, the reduced,
trivalent form [As(lll)] normally is found in ground water
(assuming anaerobic conditions) and the oxidized, pen-
tavalent form [As(V)] in surface water (assuming aerobic
conditions), although this does not always hold true for
ground water, where both forms have been found to-
gether in the same water source. Arsenate exists in four
forms in aqueous solution based on pH: H3AsO4,
H2AsO4~, HAsO42~, and AsO,,3". Similarly, arsenite exists
in five forms: H4AsO3+, H3AsO3, H2AsO3~, HAsO32~, and
AsOg3". As shown in Figure 1-1, which contains solubility
diagrams for As(lll) and As(V), ionic forms of arsenate
dominate at pH >3, while arsenite is neutral at pH <9
and ionic at pH >9. Conventional treatment technologies
used for arsenic removal, such as coagulation/filtration
and lime softening, rely on adsorption and coprecipita-
tion of arsenic to metal hydroxides. Therefore, the va-
lence and species of soluble arsenic are very significant
in evaluating arsenic removal.
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.1
.032
a.
.01
.0032
.001
-H2AsO3+
Conditions
As(III) .Ippm
10
12
14
pH
S
n.
/ HyAsQ.- \ /" HAsO42- \ /AsO43-
i * * \ / * \ / *
X
/ I
x
Conditions '
As(V) .Ippm /
/
.0032
.001
\ i
\ i
\ i
\ i
\ i
i__i
\ 5
10
12
14
pH
Figure 1-1. Solubility Diagrams for As(lll) and As(V)
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Although soluble arsenic species typically make up the
majority of the total arsenic concentration in natural
waters, some research indicates that particulate arsenic
can exist at significant concentrations. Studies by Chen
et al. (1994) and Hemond (1995) measured particulate
arsenic at levels of 17 and 50% of the total arsenic con-
centration, respectively, in the subject source waters.
Therefore, determination of the particulate arsenic con-
centration is important because it can provide insight into
the arsenic removal mechanisms that occur during treat-
ment.
1.1.2 Determination of Arsenic Species
Although total arsenic can be effectively preserved in
field samples, presently no method exists to consistently
preserve inorganic arsenic species in field samples. Pre-
servation of total arsenic is accomplished by acidifying
the sample to pH < 2 in the field. However, a high level
of ambiguity exists when acids such as nitric acid (HNO3)
or hydrochloric acid (HCI) are used to preserve inorganic
species of arsenic. Interconversion of As(lll) and As(V)
in samples preserved with 0.05 N HCI have been re-
ported to occur within one day (Andreae, 1977). Another
laboratory study conducted by Eaton et al. (1997) exam-
ined preservation of arsenic using humic acid, ascorbic
acid, and HCI; the study concluded that no effective
methods exist for preserving As(lll) and As(V) in water
samples. Some researchers have used freezing of sam-
ples as a means of preserving the inorganic species of
arsenic. However, freezing is neither a cost-effective nor
a practical method for field sampling.
In response to the lack of techniques available for ade-
quately preserving arsenic species, field speciation pro-
tocols have been developed by Ficklin (1982), Clifford et
al. (1983), and Edwards et al. (1998). In each of these
studies, an anion exchange resin column is used for field
speciation of arsenic. Ficklin (1982) used a strong anion
exchange resin (Dowex 1 x 8, 100-200 mesh, acetate
form) in a 10 cm x 7 mm glass column to sieparate
As(lll) from As(V) in water samples that had been filtered
through a 0.45-um membrane filter and acidified with 1 %
HCI. The resin was supplied in chloride form and was
converted to the acetate form. However, in the protocol
by Clifford et al. (1983), a chloride-form strong base anion
resin (ASB-2, 30-60 mesh) was used to separate As(lll)
from As(V). In this method, the sample was not filtered
or preserved with acid. Both Ficklin and Clifford used a
graphite-furnace atomic-absorption spectrophotometer
(GFAAS) to determine the arsenic concentration.
More recently, Edwards et al. (1998) made the following
modifications to Ficklin's method: (1) substituted 50- to
100-mesh resin for the 100- to 200-mesh resin to allow
faster sample flow; (2) used 12-cm x 15-mm polypro-
pylene columns to improve safety and speed of sample
treatment; (3) Used 0.05% H2SO4 instead of 1% HCI to
acidify samples prior to resin treatment. Edwards et
al.'s use of H2SO4 helped to prevent potential problems
associated with overacidification of the sample, and also
helped to prevent CP from interfering with the inductively
coupled plasma/mass spectrometry (ICP-MS) analysis.
The reported recoveries of As(lll) and As(V) ranged from
80 to 120% by Ficklin (1982), 95 to 117% by Clifford et
al. (1983), and 100 to 105% by Edwards et al. (1998).
For this study, the decision was made to utilize a field
speciation technique similar to that used by Edwards et
al. (1998).
1.1.3 Treatment Technologies for
Arsenic Removal
Several common treatment technologies are used for re-
moval of inorganic contaminants, including arsenic, from
drinking water supplies. Large-scale treatment facilities
often use conventional coagulation with alum or iron
salts followed by sedimentation and filtration to remove
arsenic. Lime' softening is another common, conven-
tional treatmeht process that can potentially remove
arsenic from source waters. Smaller-scale systems and
point-of-entry systems often use anion exchange resins
or activated alumina. Other arsenic removal technologies
include manganese greensand, reverse osmosis, electro-
dialysis reversal (EDR), nanofiltration, and adsorption on
activated carbon. This report focuses on the two conven-
tional treatment processes commonly used for arsenic
removal at large-scale operations: coagulation/filtration
and lime softening. Two additional reports will be devel-
oped that focus on (1) iron removal plants and (2) anion
exchange and activated alumina plants.
1.1.3.1 Coagulation/Filtration
Conventional coagulation/filtration is a common water
treatment methodology used to remove suspended and
dissolved solids from source water. The coagulation pro-
cess promotes aggregation of the suspended solids to
form floes, which then can be removed through sedimen-
tation and/or filtration. Coagulation is typically described
as a process consisting of three steps: coagulant forma-
tion, particle destabilization, and interparticle collisions.
The first two steps, coagulant formation and particle de-
stabilization, occur during rapid mixing, and the third
step occurs during flocculation. Alum and iron (III) salts,
such as ferric chloride, are the most common coagulants
used for drinking water treatment (Amirtharajah and
O'Melia, 1990).
Coagulation using alum and iron (III) salts can be used
to remove dissolved inorganic drinking water contami-
nants, such as arsenic. Removal mechanisms for dis-
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solved inorganics consist of two primary mechanisms:
adsorption and occlusion (Benefield and Morgan, 1990).
During the adsorption process, the dissolved contami-
nant attaches to the surface of a particle or precipitate.
Occlusion occurs when the dissolved contaminant is
adsorbed to a particle and then entrapped as the particle
continues to agglomerate. Several factors affect the co-
agulation process, including coagulant dosage, pH, tur-
bidity, natural organic mater (NOM), anions and cations
in solution, zeta potential, and temperature (Amirtharajah
and Q'Melia, 1990).
Numerous bench- and pilot-scale studies and some
short-term full-scale evaluations have been performed to
evaluate arsenic removal using conventional coagula-
tion/filtration using alum and iron (III) salts. Most of these
studies have focused on removal of As(V) rather than
As(lll) because better As(V) removal can be achieved
under comparable conditions, and As(lll) can easily be
converted to As(V) using a strong oxidant such as chlo-
rine (Hering et al., 1996; Sorg, 1993). Ferric and alum
coagulation are equally effective on a molar basis
(Edwards, 1994). However, on a weight basis (e.g., mg/L
of ferric chloride vs. mg/L of alum), coagulation with iron
(III) salts achieves better removal than coagulation with
aluminum salts (Sorg and Logsdon, 1978; Sorg, 1993;
Chen, B.C., et al., 1994; Scott et al., 1995). These results
are observed primarily because iron hydroxide is less
soluble than aluminum hydroxide over a wider pH range
(Benefield and Morgan, 1990). McNeil! and Edwards
(1997a) observed that aluminum floes with sorbed arse-
nic could pass through filters and that arsenic removal
increased when capture of aluminum floes increased.
Other research indicates that As(V) removal is not pH
dependent between pH 5.5 to 8.5 when iron coagulants
are used, although As(V) removal efficiency decreases
above pH 7 using alum (Sorg, 1993).
Previous studies also indicate that arsenic removal is
directly correlated with coagulant dosage (i.e., more co-
agulant increases arsenic removal) (Sorg and Logsdon,
1978; Sorg, 1993; Hering et al., 1996; Gulledge and
O'Conner, 1973). Also, arsenic removal efficiency ap-
pears to be independent of initial arsenic concentration
at levels of interest to drinking water treatment (Hering et
al., 1996; Chen, R.C., et al., 1994; Edwards, 1994). Al-
though no correlation between turbidity removal and arse-
nic removal has been established, turbidity removal is a
prerequisite for arsenic removal (Chen, B.C., et al.,
1994).
1.1.3.2 Lime Softening
Lime softening commonly is used to reduce hardness in
source waters. Hardness is due primarily to the pres-
ence of calcium and magnesium ions. The lime provides
hydroxide ions that increase pH, which results in calcium
and magnesium removal due to the formation of CaCO3
and Mg(OH)2 precipitates. Also, lime softening has been
used for removal of heavy metals, radionuclides, dis-
solved organics, and viruses (Benefield and Morgan,
1990) through adsorption and occlusion with calcium
carbonate and magnesium hydroxide. The typical lime
softening treatment process train includes rapid mixing
of the lime, flocculation of solids, and sedimentation.
These three processes are often combined into a single
unit referred to as a solids-contact softener (Benefield
and Morgan, 1990). Filtration usually follows these three
processes. Lime and lime-soda typically are used for
softening, and selection is dependent on the type of
hardness. Lime alone is used for source waters that
contain little or ho noncarbonate hardness, while high
noncarbonate hardness may require both lime and lime
soda. Caustic soda is sometimes used instead of lime
and lime-soda to decrease sludge production (increases
dissolved solids, but produces less sludge).
Only a few studies have been conducted to evaluate
arsenic removal during lime softening. Bench-scale and
pilot-scale studies by Sorg and Logsdon (1978) indicate
that arsenic removal during lime softening is pH
dependent. Bemoval of As(lll) and As(V) are low at pH
less than 10; however, As(V) removal approaches 100%
and As(lll) removal approaches 75% at pH greater than
10.5. As part of a survey of full-scale water treatment
plants by McNeill and Edwards (1995), lime softening
plants were able to achieve up to 90% arsenate removal
if pH was high enough to precipitate magnesium hydrox-
ide (i.e., near pH 11). When only CaCO3 precipitated,
As(V) removal was between 0 and 10%; however, when
CaCO3 and Mg(OH)2 were precipitated, As(V) removals
were between 60 and 95% (McNeill and Edwards,
1995). Coprecipitation of As(V) with Mg(OH)2 appears to
be the primary arsenic removal mechanism for As(V)
during lime softening.
McNeill and Edwards published results from bench-scale
experiments designed to evaluate the basic mechanisms
of arsenic removal during lime softening (McNeill and
Edwards, 1997b). Consistent with previous findings,
greater than 90% arsenate removal was observed at
above pH 11 where Mg(OH)2 was precipitated (McNeill
and Edwards, 1997b). Also, it was determined that trace
amounts of orthophosphate and the presence of carbon-
ate could limit arsenate removal by Mg(OH)2. If man-
ganese was present in the source water, some As(V) re-
moval could be achieved through sorption with Mn(OH)2,
although Mn3(AsO4)2 precipitate formation was not deter-
mined to be a major mechanism (McNeill and Edwards,
1997b). Other findings from the same study indicated
that arsenate removal percentages were relatively con-
stant for arsenic concentrations between 5 to 75 ug/L.
Also, addition of iron before softening could increase
-------
arsenic removal; however, competition between arsenic
and carbonate for sorption sites on the iron hydroxide
reduced the removal efficiency to levels below those
normally achieved with a conventional coagulation/filtra-
tion process using iron (111) salts (McNeill and Edwards,
1997b).
1.1.4 Data Gaps
The removal of arsenic from drinking water by conven-
tional coagulation/filtration has been extensively studied
at the laboratory and pilot-scale level. To a lesser de-
gree, arsenic removal by lime softening has been stud-
ied at the laboratory and pilot-scale level. Although some
short-term full-scale evaluations have been performed
for both treatment processes, little data exist on the
capability of these processes in full-scale applications to
reduce arsenic on a sustained basis. Thus, a need exists
to determine the effectiveness of coagulation/filtration
and lime softening to produce drinking water low in arse-
nic on a long-term basis, under varying operational and
seasonal conditions.
Another data gap that exists concerning conventional
drinking water treatment processes is the production and
disposal of residuals. Currently, little or no data exist on
the amounts and the chemical composition of residuals
generated by the arsenic removal processes and the
methods that are environmentally acceptable for their
disposal. Therefore, information needs to be collected on
the quality and the chemical characteristics of the wastes
produced by the coagulation/filtration and lime softening
plants.
1.2 Objectives
One objective of this project was to evaluate the effec-
tiveness of conventional coagulation/filtration and lime
softening to consistently reduce arsenic concentrations in
source water to low levels. This report presents the re-
sults of weekly monitoring for approximately one year at
two coagulation/filtration plants and one lime softening
plant.
Another objective of this study was to examine the resid-
uals produced during treatment at conventional coagula-
tion/filtration and lime softening plants. Information was
collected on the quality and chemical characteristics of
the wastes produced by these drinking water treatment
processes.
1.3 Report Organization
Section 1.0 provides background information for the field
study and project objectives. Section 2.0 of this report pre-
sents the conclusions from the study of the two conven-
tional coagulation/filtration plants and the lime softening
plant. Section 3.0 describes the materials and methods
used to conduct this study. Section 4.0 discusses the
results of the study and Section 5.0 provides specific
information on quality assurance/quality control (QA/QC)
procedures. Section 6.0 is a list of references cited in the
text. Appendices A, B, and C present the complete set of
analytical data collected at Plants A and B (the two coagu-
lation/filtration plants), and C (the lime softening plant),
respectively, during long-term sampling.
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2. Conclusions
The U.S. EPA currently is in the process of revising the
arsenic MCL, and it is anticipated that the revised stand-
ard will be significantly lower than the existing MCL of
0.05 mg/L Therefore, there is a need to determine the
ability of existing treatment processes to consistently re-
move arsenic to low levels. The primary objectives of
this project were to document arsenic removal at two
conventional coagulation/filtration plants and one lime
softening plant, and to characterize the residuals (sludge
and supernatant water) at these treatment plants.
The study was divided into three major phases: source
water sampling (February 1998), preliminary sampling
(April and May 1998), and long-term evaluation (June
1998 through June 1999). For the first phase, Battelle
staff traveled to each facility to conduct source water
sampling, which provided information on source water
characteristics. The second phase, preliminary sampling,
consisted of a 4-week sampling period to refine the sam-
pling approach before implementing the long-term evalu-
ation phase. Battelle staff again traveled to each facility
to coordinate the first sampling event and train plant per-
sonnel in sampling procedures for subsequent events.
The third phase, long-term evaluation, consisted of weekly
sample collection and analysis at each of the water treat-
ment plants, sludge sampling (November and December
1998), and recycle supernatant water (Plant A) and super-
natant discharge (Plants B and C) sampling (November
1998 through June 1999). During the long-term evalu-
ation phase, plant personnel conducted sampling and
Battelle staff coordinated sampling logistics.
The primary focus of this study was the long-term per-
formance of two coagulation/filtration plants and one
lime softening plant. The two coagulation/filtration plants
demonstrated the ability to consistently achieve low
levels of arsenic in the treated water (i.e., less than
5 ug/L). Adsorption and coprecipitation of As(V) with
metal hydroxides, such as iron hydroxide and alum hy-
droxide, are believed to be the primary arsenic removal
mechanisms in coagulation/filtration plants. As(lll) re-
moval during coagulation/filtration was not observed
during this study because both plants had surface water
source where the soluble arsenic was primarily arsenate.
Interestingly, Plant B conducted a 6-week test wherein
the coagulant was changed from alum to liquid poiy-
aluminum chloride (i.e., PAX-18). During this test, arse-
nic removal was negatively impacted. Average removal
efficiency using alum was 84% compared to 43% using
PAX-18. The difference in removal efficiencies may be
the result of the difference in pH achieved with each
coagulant.
The lime softening plant (Plant C) evaluated for this
project was not able to consistently reduce arsenic to
low levels in the treated water. The plant did not operate
at a significantly high pH to precipitate magnesium hy-
droxide, and the arsenic removal by coprecipitation with
calcium carbonate is low (<10%) (Sorg and Logsdon,
1978; McNeill and Edwards, 1997b). However, arsenic
removal efficiency at Plant C was approximately 45%. It
is believed that the primary mechanism of arsenic re-
moval is coprecipitation of As(V) with iron that is present
in the source water. Prior research indicates that arsenic
removal by iron oxides during lime softening can be
hindered by competition for sorption sites with carbonate
(McNeill and Edwards, 1997b). Also, little research ex-
ists on the coprecipitation of arsenic and iron hydroxide
at pH values greater than 8.
The secondary focus of this study was on residual pro-
duction and the chemical characteristics of the residuals.
None of the sludge sampled during this study qualified
as a hazardous waste based on the Toxicity Charac-
teristic Leaching Procedure (TCLP) tests for metals.
Therefore, the sludge generated by these treatment pro-
cesses should be accepted by nonhazardous waste
landfills. However, stricter requirements in California re-
garding hazardous waste classification were not met by
Plant A based on total arsenic concentrations. Super-
natant water from sludge lagoons was either discharged
to surface water bodies under state permits (Plants B
and C) or recycled back to the inlet (Plant A). The recy-
cle supernatant did not appear to contain high concen-
trations of arsenic. The ecological risks associated with
discharging these waters were not assessed.
-------
3. Materials and Methods
This section discusses the materials and methods used
for performing the source water, preliminary, and long-
term sampling and data collection at two coagulation/fil-
tration plants and one lime softening plant. Section 3.1
describes the general project approach. Section 3.2
describes the preparation of arsenic speciation kits and
sample coolers. Section 3.3 provides detailed sampling
procedures. Section 3.4 discusses pertinent analytical
procedures.
3.1 General Project Approach
Several consecutive tasks were performed to accomplish
the project objectives described in Section 1.2. These
tasks involved the following activities:
Select treatment plants and conduct an initial site
visit to collect source water samples at each
selected plant
Prepare a preliminary sampling and data
collection plan for each plant
Finalize the sampling and data collection plan
after completion of four weekly preliminary
sampling events at each plant
Implement the final sampling and data collection
plan with weekly sampling events at each plant for
one full year.
For initial plant selection, a list of potential treatment
plant candidates was compiled. Plant operators or other
key personnel were contacted via telephone to obtain/
confirm information and solicit interest in participating in
the project. Each facility was evaluated, in order of
importance, on source water arsenic concentrations,
source water type, available manpower to conduct the
year-long study, availability of historical arsenic data,
and plant size. Batteile recommended the selection of
two coagulation/filtration plants (designated as Plants A
and B) and one lime softening plant (designated as
Plant C) for initial site visits and source water sampling.
These recommendations were later approved by the
EPA Work Assignment Manager (WAM). The informa-
tion collected during the site visits, including the concen-
tration and speciation of arsenic in each source water,
was tabulated!and used as the basis for the final plant
selection.
Following the final plant selection (Plants A, B, and C
again were selected), a preliminary sampling and data
collection plan was prepared for each plant to document
the plant's operation and performance for arsenic re-
moval and the critical parameters that would impact the
removal. Each preliminary plan also described the data
collection effort to characterize the residuals produced
by the treatment process. The approved preliminary
plans were implemented at Plants A, B, and C during a
4-week trial period. A Batteile staff member revisited the
plants during the first week of the trial period to observe
plant operations, perform sampling, conduct training of
plant support personnel, and establish/coordinate all re-
quired logistics (such as receiving/shipping of sample
coolers, chain-of-custody coordination, communication
methods, and emergency/contingency plans). The re-
maining three sampling events during the preliminary
sampling were performed by a designated point of con-
tact (POC) or an alternate at each plant. The experience
gained during'the trial period was used to finalize the
long-term sampling and data collection plans.
All water and residual samples were collected and
analyzed in accordance with the Category III Quality
Assurance Project Plan (QAPP) prepared by Batteile
(1998) for this project. Water samples were collected
weekly at Plants A, B, and C at three locations: (1) the
inlet to the treatment plants (IN); (2) before the filtration
process (PF); and (3) after the filtration process/at the
plant outlet (AF). During the preliminary and long-term
sampling phases, field arsenic speciation was conducted
once every four weeks. Starting from November 1998,
samples of recycle supernatant water (from the settling
pond at Plant A) or supernatant discharge water (from
lagoons at Plants B and C) were collected once every
four weeks from each plant. Three sludge samples also
-------
were collected from either the settling pond or lagoons
during one sampling event at each of the three plants.
All sample containers and arsenic speciation kits were
prepared by Battelle and sent in coolers on a weekly
basis to each plant via Federal Express. The coolers
were returned to Battelle immediately after the sample
collection had been completed. Analyses of arsenic, alu-
minum, iron, and manganese in water were conducted
by Battelle's ICP-MS laboratory. Wilson Environmental
Laboratories in Westerville, OH, was subcontracted to
perform all other chemical analyses. Battelle coordinated
all sampling logistics.
3.2 Preparation of Sampling Kits and
Sample Coolers
All arsenic speciation kits, recycle supernatant water/
supernatant discharge sampling kits, and sample coolers
were prepared at Battelle. The following sections de-
scribe the relevant preparation procedures.
3.2.1 Preparation of Arsenic
Speciation Kits
The arsenic field speciation method used an anion
exchange resin column to separate the soluble arsenic
species, As(V) and As(lll). A 250-mL bottle (identified as
bottle A) was used to contain an unfiltered sample,
which was analyzed to determine the total arsenic con-
centration (both soluble and particulate). The soluble
portion of the sample was obtained by passing the unfil-
tered sample through a 0.45-um screw-on disc filter to
remove any particulate arsenic and collect the filtrate in
a 125-mL bottle (identified as bottle B). Bottle B con-
tained 0.05% (volume/volume) ultra-pure sulfuric acid to
acidify the sample to about pH 2. At this pH, As(lll) was
completely protonated as H3AsO3, and As(V) was pres-
ent in both ionic (i.e., H2AsO4") and protonated forms
(i.e., H3AsO4) (see Figure 1-1). A portion of the acidified
sample in bottle B was run through the resin column.
The resin retains the As(V) and allowed As(lll) (i.e.,
HjAsO,,) to pass through the column. (Note that the resin
will retain only H,AsO4" and that H3AsO4, when passing
though the column, will be ionized to H2AsO4" due to
elevated pH values in the column caused by the buffer
capacity of acetate exchanged from the resin.) The elute
of the column was collected in another 125-mL bottle
(identified as bottle C). Samples in bottles A, B, and C
were analyzed for total arsenic using ICP-MS. As(lll)
concentration was the total arsenic concentration of the
resin-treated sample in bottle C. As(V) concentration
was calculated by subtracting As(lll) from the total solu-
ble arsenic concentration of the sample in bottle B.
Arsenic speciation kits were prepared in batch at Battelle
based on a method modified from Edwards et al. (1998).
Each arsenic speciation kit contained the following:
Two anion exchange resin columns
Primary and duplicate A, B, and C bottles
One 400-mL disposable beaker
Two 60-mL disposable syringes
Several 0.45-um syringe-adapted disc filters.
Each speciation kit was packed in a plastic zip-lock bag
along with latex gloves and a step-by-step speciation
sampling instruction sheet. All chemicals used for pre-
paring the kits were of analytical grade or higher. The
arsenic speciation kits were prepared according to the
following procedures:
Resin Preparation,. Before packing into columns,
the anion exchange resin (Dowex 1-X8, 50-100
mesh) was converted from the chloride form (as
supplied by Supelco) to the acetate form accord-
ing to the method used by Edwards et al. (1998).
First, 1 kg of the resin was placed in a 3-L beaker.
One liter of 1N sodium hydroxide (NaOH) then
was added to the resin, stirred for an hour using
an overhead stirrer, and drained. This NaOH rinse
was repeated sequentially three times. The
NaOH-treated resin was then rinsed with two 1 -L
batches of reagent grade water, followed by three
acetic acid rinses. Each acetic acid rinse
consisted of adding 1 L of 1N reagent grade
acetic acid to the resin, stirring for 5 minutes, and
draining the spent acid. The acetic acid-treated
resin was subsequently rinsed with 3-L batches of
reagent-grade water. The resin slurry was stored
in a 2-L bottle and kept moist until use.
Anion Exchange Column Preparation. The
resin columns used were 12 cm x 15 mm in size
and made of polypropylene (Bio-Rad Labora-
tories, CA). Each column was slurry packed with
about 20 g (drained weight) of the prepared resin,
yielding a resin depth of approximately 10.5 cm.
The column was sealed with two plastic caps (one
each on top and bottom) to prevent contamination
and retain moisture prior to use.
Sample Bottles. VWRbrand TraceClean high-
density polyethylene (HOPE) sample bottles (250
and 125 mL) were used to prepare bottles A, B,
and C. Bottles A and C were spiked with 500 and
250 uL of concentrated ultra-pure nitric acid
(HNO3), respectively; and bottle B was spiked with
1.25 mL of 5% (volume/volume) ultra-pure sulfuric
acid (H2SO4). H2SO4 was used to acidify the
sample in bottle B because chloride (Cl~) in HCI
could interfere with the ICP-MS arsenic detection
-------
and HNO3 (an oxidizing agent) could damage the
resin or form nitric acid-arsenic redox couples
(Edwards et al., 1998).
Beaker, Syringes, and Filters. One 400-mL
disposable plastic beaker was used to collect a
water sample. Samples were filtered using 60-mL
disposable plastic syringes with 0.45-um screw-on
disc filters. All disposable beakers, syringes, and
filters were rinsed with distilled (Dl) water and air-
dried before being packed into the sampling kits.
3.2.2 Preparation of Recycle Backwash
Water/Supernatant Discharge
Sampling Kits
The recycle backwash water/supernatant discharge sam-
ples were collected for pH, hardness (Plant C only), total
and soluble As, Al, Fe, and Mn measurements. Each
sampling kit contained the following items:
Primary and duplicate A and B bottles (both
preserved with HNO3) to contain unfiltered and
filtered samples for total and soluble As, Al, Fe,
and Mn analyses
One 400-mL disposable beaker
Two 60-mL disposable syringes
Several 0.45-um screw-on disc filters
Bottles provided by Wilson Environmental
Laboratories used for pH and hardness (Plant C
only) analyses.
The sampling kit was prepared in a similar way as the
arsenic speciation kit except that bottle B was preserved
with HNO3 instead of H2SO4. The sampling kit was
packed in a plastic zip-lock bag along with latex gloves
and a step-by-step sampling instruction sheet.
3.2.3 Preparation of Sample Coolers
Sample containers for analysis of all water quality param-
eters except for total As, Al, Fe, and Mn were provided
by Wilson Environmental Laboratories. These containers
were new, rinsed with Dl water, allowed to air dry, and
contained appropriate preservatives before being deliv-
ered to Battelle. These bottles were labeled with the let-
ter D, E, F, or G, designating the specific analysis to be
performed. Table 3-1 lists the sample container size and
type (for water and sludge samples), sample preserva-
tion used, analysis to be performed, and holding time. All
sample containers were labeled prior to shipment.
Table 3-1. Sample Containers and Preservation Methods
Container Size
Container Type
Preservation Method
Analyte
Hold Time
Arsenic Speciation Samples
250 mL (A) certified clean HOPE bottles
125mL(B) certified clean HOPE bottles
125mL(C) certified clean HOPE bottles
4ฐC, HNO3 for pH <2
4ฐC, 0.05 % H2SO4
4ฐC, HNO3 for pH <2
Recycle Backwash Water/Supernatant Discharge Samples
250 mL (D) plastic
250 mL (A)
250 mL (B)
certified clean HOPE bottles
certified clean HOPE bottles
Water Quality Parameter Samples
250 mL (D) plastic
250 mL (D)
plastic
4ฐC
4ฐC, HNO3forpH<2
4ฐC, HNO3forpH<2
4ฐC
4ฐC
Total As, Al, Fe, Mn 6 months
Dissolved As, Al, Fe, Mn 6 months
Dissolved As, Al, Fe, Mn 6 months
pH immediate
TSS 7 days
Total As, Al, Fe, Mn 6 months
Dissolved As, Al, Fe, Mn 6 months
Alkalinity 14 days
pH immediate
Turbidity 48 hours
Sulfate 28 days
Fluoride 28 days
250 mL (E)
250 mL (F)
500 mL (G)
Sludge Samples
8oz(SL1)
4 oz (SL2)
4 oz (SL2)
TOC = total organic carbon.
TSS = total suspended solids.
plastic
plastic
glass
glass jar
glass jar
glass jar
4ฐC, HNO3 for pH<2
4ฐC, H2 SO4 for pH <2
4ฐC, H2SO4 for pH<2
4ฐC
4ฐC
4ฐC
Hardness
NCV/NCV
; TOC
Total As, Al, Fe, Mn
Water content, pH,
: TCLP metals
Water content, pH,
TCLP metals
6 months
28 days
14 days
6 months
14 days
14 days
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Figure 3-1 presents an example sample bottle label. The
sample identification (ID) consisted of five parts, includ-
ing a two-letter code for a water treatment plant, the
sampling date (mm/dd/yy), a two-letter code for a spe-
cific sampling location (e.g., IN for inlet water, PF for
before the filtration process, and AF for after the filtration
process or at the plant outlet), a one-letter code desig-
nating the analyses to be performed (see Table 3-1),
and a code indicating whether the sample is a primary
sample or a field duplicate sample. A field duplicate was
identified by adding a "dup" to the label and a primary
sample used no additional coding.
AC-02/15/98-PF-B-DUP
Date: 02/15/98 Time: 11am
Collector's Name: Sample Collector
Location: Any City WTP
Sample ID: AC-02/15/98-PF-B-DUP
Send to: Battelle
Analysis Required: Total As, Al, Fe, and Mn
Preservative: 0.05% sulfuric acid
Figure 3-1. Example of Sample Bottle Label
After the sample bottles were labeled, they were placed
In coolers subdivided into three compartments, each cor-
responding to a specific sampling location at each plant.
Color coding was used to identify sampling locations and
all associated sample bottles. For example, red, blue,
and yellow were used to designate sample locations for
raw water at the plant inlet, before the filtration process,
and after the filtration process (or at the plant outlet),
respectively. Other sampling and shipping-related mater-
ials, including latex gloves, chain-of-custody forms, pre-
paid Federal Express air bills, sampling instructions, ice
packs, and bubble wrap, also were packed into coolers.
Arsenic speciation kits or recycle supernatant water/dis-
charge sampling kits were included in the cooler when the
arsenic speciation or recycle supernatant water/discharge
samples were collected. After preparation, sample coolers
were sent to all plants every Thursday via Federal Ex-
press for the following week's sampling activity. Figure 3-2
shows photographs of a sample cooler with three sam-
ple compartments and a color-coded instruction sheet
placed under the lid of the cooler.
3.3 Sampling Procedures
3.3.1 General Approach and Sampling
Schedules
One or two Battelle staff members traveled to each plant
to collect source water samples, meet plant operators,
solicit interest in participating in this year-long sampling
program, and obtain plant design and operating informa-
tion and historical water quality data. After the plant
selection, one Battelle staff member returned to each
plant to collect samples at selected sampling locations
and train the plant operator or a designated POC to per-
form sampling and field arsenic speciation. The remain-
ing three preliminary sampling events and long-term
sampling events then were conducted by the trained
plant personnel. Residuals sampling, including a single
sludge sampling event and the monthly collection of re-
cycle supernatant water or supernatant samples from
either a settling pond or lagoon also were collected by the
designated plant employees with detailed instructions
provided by Battelle over the telephone. Table 3-2 sum-
marizes the sampling activities at Plants A, B, and C.
During the preliminary and long-term sampling, the sam-
ple collection was conducted on a 4-week cycle, with
each week having unique sampling requirements. Ta-
bles 3-3 (Plants A and B) and 3-4 (Plant C) summarize
the schedules for the initial source water, the prelimi-
nary, the long-term, and the sludge sampling.
After receipt of the weekly sample coolers, plant person-
nel began sampling activities at the selected locations on
the scheduled dates. Upon completion, all sample bot-
tles were sealed with tape and placed in the same cool-
ers for return shipment to Battelle by Federal Express.
Upon receipt of the samples, the designated Battelle
sample custodian immediately examined and compared
the conditions of all sample bottles with those indicated
in the chain-of-custody forms. Samples then were dis-
tributed to Battelle's ICP-MS laboratory and Wilson Envi-
ronmental Laboratories for chemical analyses.
Throughout the duration of the study, Battelle staff main-
tained frequent telephone contact with each plant to
ensure that all sampling activities were carried out as
planned. For example, after scheduled arrival of sample
coolers, one Battelle staff member would call to confirm
the receipt of the coolers, answer any questions, discuss
irregular plant operations and unusual observations, and
propose/suggest corrective actions. When available, re-
sults of the chemical analyses also were discussed over
the telephone and data sheets were sent quarterly to the
plants for review. Further, plant operational and water
quality data (such as plant flowrate, chlorine addition
rate, ferric chloride or alum dosage [Plants A and B],
lime dosage [Plant C], pH, hardness [Plant C], and tur-
bidity) were sent along with sample coolers or trans-
mitted via facsimile to Battelle for information/evaluation.
3.3.2 Arsenic Field Speciation Procedure
The procedures for performing field arsenic speciation
are shown in Figure 3-3 and are described as follows
("steps" refer to Figure 3-3):
10
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Figure 3-2. Photographs of a Typical Sample Cooler (with Three Sample Compartments) and a Color-
Coded Instruction Sheet
Bottle A: A 400-mL disposable plastic beaker was
rinsed thoroughly with the water to be sampled.
The beaker then was used to collect a water
sample and to fill bottle A with an aliquot of that
sample (step 3). If necessary, additional sample
water was added to the beaker after bottle A was
filled to complete arsenic speciation sampling.
Bottle B: A 60-mL disposable plastic syringe was
rinsed thoroughly with the water in the plastic
beaker by completely filling and emptying the
syringe (step 4). After attaching a 0.45-um disc
filter and wasting about 10 drops of the filtrate, the
syringe was used to filter the water sample from
the beaker and fill bottle B. Bottle B then was
tightly capped and vigorously shaken for about
15 seconds to allow thorough mixing of the filtered
water and sulfuric acid (step 5).
11
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Table 3-2. Summary of Sampling Activities at Plants A, B, and C
Sampling Activities
Initial source water sampling
Preliminary sampling
Long-term sampling
Sludga sampling
Recycle water sampling
Sampling
Frequency
Once
Weekly
Weekly ""
Once
Weekly
Plant A
02/03/98
04/09/98 through 04/30/98
06/24/98 through 06/16/99
12/02/98
1 1/1 1/98 through 06/1 6/99
PlantB
02/05/98
04/23/98 through 05/14/98
06/25/98 through 06/17/99
12/15/98
1 1/12/98 through 06/17/99
Plant C
02/27/98
04/27/98 through 05/18/98
06/22/98 through 06/14/99
11/16/98
1 1/09/98 through 06/14/99
(a) Exceptforthe weeks of 11/23/98,12/21/98, and 12/28/98.
Table 3-3. Summary of Sampling Schedule for Plants A and B
Water Sampling
Analyte
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Al (total)
Fe (total)
Mn (total)
Al (dissolved)
Fe (dissolved)
Mn (dissolved)
Alkalinity
Sulfata
NO,-NO, (N)
TOG
Turbidity
PH
Hardness
Ca Hardness
Mg Hardness
TCLP Metals
Percent Moisture
PH
As (total)
Fe (total)
Initial Source
Water Sampling
(Once)
W>
W">
W>
W"
W">
W
W"
W"
W"
wซ
W"
W1"
W"1
W"
W"
W1"
W"
Preliminary Sampling Cycle
Week 1 Week 2
W1"
W"
W1
W"
Wc>
W"
W"
W1"
W
W
W
W
W
W
W
W
W
W
W"
ww
Ww
w">
W"
W"
Week 3 Week 4
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
Week
W1"
W1"
W1"
W"1
W11"
W"
w"ป
W"
W1'1
W">
ww
W
W
W
W
W
W
Long-Term
Sampling Cycle
1 Week 2 Week 3 Week 4
W
W
W
W
W"
W'ซ
W"
W"
W"
W"
W, R<"
R""
R">
W, R">
W, R">
W, R1"
W, R"1
W, Rw
W, R("
W
W
W
W
W
W, R1"
W
W
W
W
W
W
W
W
W
W
Sludge
Sampling
(Once)
S
S
S
S
S
(a) s Duplicate samples collected and analyzed.
W s Water samples collected from the inlet, prefiltration, and after filtration locations.
R = Recycle supernatant water sample collected at Plant A; Supernatant discharge water sample collected at Plant B.
S s Sludge sample; three sludge samples were collected at each of Plants A and B.
Empty cells indicate no samples taken.
Bottle C: The protective caps on the top and
bottom of a resin column were removed and
approximately 40 ml_ of the water in bottle B was
wasted through the column. This initial 40 ml_ was
used to displace the water in the resin column and
to ensure attainability of a representative sample
from the column. The resin column then was posi-
tioned over bottle C, and the water from bottle B
was passed through the column until approxi-
mately 20 mL of the resin-treated sample had
been collected in bottle C (step 6).
The procedure as described under the above
three bullets was repeated to obtain duplicate
bottles A, B, and C.
Upon completion, the individual performing the
speciation signed on a chain-of-custody form
(step 7). All sample bottles (for arsenic speciation
and other water quality parameters), along with
the signed chain-of-custody form, were placed in
the original cooler with ice packs and shipped via
Federal Express to Battelle (step 8).
12
_
-------
Table 3-4. Summary of Sampling Schedule for Plant C
Analyte
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Al (total)
Fe (total)
Mn (total)
Al (dissolved)
Fe (dissolved)
Mn (dissolved)
Alkalinity
Sulfate
NO3-NO2 (N)
TOC
Turbidity
pH
Hardness
Ca Hardness
Mg Hardness
TCLP Metals
Percent Moisture
pH
As (total)
Fe (total)
Initial Source
Water Sampling
(Once)
W*
W"ป
W"
W""
W"
W""
W"*
W'ซ
W""
W"
W""
W""
W"
W"
W"
W'*
W""
Preliminary Sampling Cycle
Week
W"
W(ซ>
W"
W""
W"1
W"
w">
W""
W
W
W
W
W
W
W
W
1 Week 2
W
W
W
W
w(!"
W""
W""
W1"1
W""
W"11
W"'1
W1"1
Week3 ' Week 4
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
'
Week
W<"
W"ป
w!"
W!a)
W1"1
W!"
w"ป
W1*
w1"
w1"
W!"
W
W
W
W
W
W
W
w
Long-Term
Sampling Cycle
1 Week 2 Weeks Week 4
W
W
W
W
W""
W*1
w">
W""
W"
w"1
w""
w1"
W, Rw
R""
R"1
W, Rw
W, Rw
W, Rw
W, Rw
W, R1"
W, R"1
W
W
W
W
W, R""
W, R""
W, R("
W, R""
W
W
W
W
W
W
W
W
W
W
W
W
Sludge
Sampling
(Once)
S
S
S
S
S
(a) = Duplicate samples collected and analyzed.
W = Water samples collected from the inlet, prefiltration, and after filtration locations.
R = Supernatant discharge water sample.
S = Sludge samples; three collected at Plant C.
Empty cells indicate no samples taken.
3.3.3 Recycle Supernatant
Water/Supernatant Discharge
Sampling Procedure
Figure 3-4 shows an instruction sheet for performing re-
cycle backwash water and supernatant discharge sam-
pling. Because both total and dissolved As, Al, Fe, and
Mn were analyzed, the procedure for recycle superna-
tant water/supernatant discharge sampling was similar to
that for arsenic speciation, except that the steps for col-
lecting samples in bottle C were omitted.
3.3.4 Sampling Procedure for Other
Water Quality Parameters
All other water quality parameters identified in Tables 3-3
and 3-4, were analyzed using samples either in bottles A,
B, and C or in bottles provided by Wilson Environmental
Laboratories (i.e., bottles D, E, F, and G). All bottles D,
E, F, and G were filled directly from sample taps and
preserved according to the respective analytical methods.
These sample bottles along with bottles A, B, and C
were placed in the original coolers with ice packs and
shipped via Federal Express to Battelle.
3.4 Analytical Procedures
The analytical procedures used for this project were
described in Section 4.0 of the QAPP prepared by
Battelle (1998). Table 3-5 presents a summary of all
analytical methods used. All of the methods used are
standard EPA methods. Analyses of As, Al, Fe, and Mn
in water samples were accomplished by ICP-MS using
EPA Method 200.8. ICP-MS was chosen as the method
for As, Al, Fe, and Mn analyses because it had a low
method detection limit (MDL) and was a relatively low-
cost method (about $35/sample). ICP-MS analyses were
conducted on a Perkin Elmer Sciex Model 6000 equipped
with a crossflow pneumatic nebulizer and an automatic
sampler. Yttrium (889Y) was added to all samples as an
internal standard to correct for instrument drift. Because
arsenic is monoisotopic, all measurements were made at
a mass/ charge ratio of 75. To eliminate an appreciable
13
-------
Step 1:
Go to sampling point
(Inlet, Prefiltratfon, or Outlet)
Important Note;
DO NOT RINSE ANY BOTTLES!!
THEY CONTAIN PRESERVATIVES!!
Step3;
Collect water sample
Preservative
a) Avoid agitation
b) Fill bottle A
Step 4:
Prepare the syringe
Fill and empty syringe to rinse
StepS;
Collect filtered sample
Preservative
(H2S04)
B
a) Refill syringe
b) Attach filter to syringe
and waste 10 drops
c) Fill bottle B
d) Cap tightly; shake (about 15 seconds)
Step 6:
Collect resin-treated sample
H;
A
a) Fill resin column from bottle B;
drain column to rinse; repeat
(waste approx. 40 mL)
Preservative
/
b) Drain column into bottle C;
repeat (collect approx. 20 mL)
Step 7:
Fill in all blanks on chain-of-custody form
Step 8:
Pack and ship samples
EPA14.CDR
a) Tighten caps of all bottles b) Tape cooler before shipping
Figure 3-3. Instruction Sheet for Arsenic Field Speciation
14
-------
Sfep 1:
Go to recycle backwash water
or supernatant discharge
sampling point
Sfep 2;
Put on gloves
I m portant Note:
DO NOT RINSE ANY BOTTLES!!
THEY CONTAIN PRESERVATIVES!!
Step 3;
Collect water sample
Preservative
(HN03)
a) Avoid agitation
b) Fill bottle A
Sfep 4:
Prepare the syringe
Fill and empty syringe to rinse
Step 5;
Collect filtered sample
a) Refill syringe
b) Attach filter to syringe
and waste 10 drops
inn*
/Preservative
I/ (HN03)
c) Fill bottle B
Sfep 6:
Fill in all blanks on chain-of-custody form
Sfep 7;
Pack and ship samples
B
a) Tighten caps of b) Tape cooler before shipping
all bottles
Figure 3-4. Instruction Sheet for Recycle Supernatant Water/Supernatant Discharge Sampling
15
-------
Table 3-5. Summary of Analytical Methods for Arsenic Treatment Study
Sample Matrix
Aqueous (Including samples collected at the
plant inlet, before the filtration process, after the
filtration process, and supernatant water from
sludge settling ponds/lagoons that was recycled
or discharged)
Sludge
Analyte
As (total)
Total Al
Total Fe
Total Mn
Alkalinity
PH
Turbidity
Hardness
so,2-
TOC
N03-/N02-
Water content
PH
TCLP metals
Total As
Total Fe
Method
EPA 200.8
EPA 200.8
EPA 200.8
EPA 200.8
EPA 310.1
EPA 150.1
EPA 180.1
EPA 215.1/242.1
EPA 375.4
EPA 415.1
EPA 353.2
ASTMD2216
SW-846 9045
SW-8461311
SW-846 305 1,6020
SW-846 305 1,6020
Analytical Laboratory
Battelle ICP/MS
Battelle ICP/MS
Battelle ICP/MS
Battelle ICP/MS
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
Wilson Environmental
interference from a chloride molecular species (40Ar35CI),
all ion current data at m/e 75 were corrected using
chloride measurements in all samples, and the MDL was
0.1 pg/L As. All the unfiltered water samples (i.e., in bot-
tle A) were digested using EPA Method 200.8 prior to
analysis. Filtered water samples (i.e., in bottles B and C)
were analyzed directly without digestion. Wilson Environ-
mental Laboratories in Westerville, OH, was subcon-
tracted to perform all other chemical analyses. QA/QC of
all methods followed the guidelines provided in the QAPP
(Battelle, 1998) and the data quality in terms of preci-
sion, accuracy, MDL, and completeness is discussed in
Section 5.0 of this report.
16
-------
4. Results and Discussion
This section presents the results of the treatment plant
selection process, which resulted in the selection of two
coagulation/filtration plants, referred to as Plants A and
B, and one lime softening plant, referred to as Plant C. In
addition, results from water and residuals sampling and
analysis at Plants A, B, and C are summarized and dis-
cussed. Complete analytical results from long-term water
sampling at Plants A, B, and C are presented in Appen-
dices A, B, and C, respectively.
4.1 Plant Selection
The plant selection process consisted of identifying po-
tential treatment facilities, contacting these facilities via
telephone, and conducting initial site visits during which
source water samples were collected and analyzed. Ini-
tially, a list was prepared consisting of six potential coag-
ulation/filtration treatment facilities and two lime soften-
ing facilities. These potential candidate facilities were
contacted to discuss the study and determine details of
plant operation. Each facility was evaluated and as-
signed an overall plant rating based, in order of impor-
tance, on source water arsenic concentrations, source
water type, available manpower to conduct the year-long
study, availability of historical arsenic data, and plant
size. Selection was based primarily on source water ar-
senic concentrations, and preference was given to facili-
ties with arsenic concentrations greater than 20 ug/L.
Another major consideration was the availability of man-
power, because the year-long study would require signi-
ficant resources. Also, it was desirable to have historical
arsenic analytical data, fairly large facilities (i.e., >20,000
people served), and to have a mix of plants using ground
water and/or surface water sources.
From the eight initial plants, three plants (two coagula-
tion/filtration and one lime softening) were selected for
site visits and source water sampling (Plants A, B, and C
in Table 4-1). The same plants that were selected for the
initial site visits also were selected for the subsequent
phases of the study. Results from source water sampling
at each of the three facilities are presented in the sec-
tions that follow.
4.2 Plant A
Water and residual samples were collected and analyzed
at Plant A, a-coagulation/filtration plant, during three
phases of the ptudy. The first phase consisted of source
water sampling used to help determine if the plant should
be considered:for additional phases. Source water sam-
pling at Plant A was performed in February 1998. Fol-
lowing source .water sampling, the second phase of the
study was initiated. This second phase consisted of
weekly water sampling for a 4-week period in April 1998
and was designed to determine if the sampling locations
and proposed, water quality analyses were appropriate
for the third phase, long-term evaluation. The third phase
was initiated in June 1998 and continued through June
1999. This long-term evaluation consisted of weekly sam-
pling and analysis of process water at three locations
throughout the treatment process. Also, arsenic speci-
ation sampling was conducted every fourth week. The
third phase of the study also included residual sample
Table 4-1. Initial List of Treatment Facilities Identified for the Study
Source Water Arsenic
Concentration, July 1994
Plant ID Process (ug/L)
A C/F
B C/F
C LS
NS
NS
33.2
Source Water Arsenic
Concentration, March 1995 Population
(ug/L) Served
66.9
33.2
52.5
2,500,000
65,000
: 35,000
Historical Data
Yes
Yes
Yes
Source
Water Type
SW
SW
GW
C/F = coagulation/filtration.
LS = lime softening.
GW = ground water.
SW = surface water.
NS = not sampled.
17
-------
collection and analysis. Recycle supernatant water sam-
ples from the settling pond were collected monthly begin-
ning in November 1998, and three sludge samples were
collected during a single sampling event from a de-
watered sludge pond.
4.2.1 Plant A Description
Plant A began operation in December 1986 and can
treat up to 600 million gallons of water per day (mgd).
However, based on discussions with plant personnel, the
average plant flowrate is approximately 420 mgd. This
plant uses ozonation, coupled with coagulation/filtration
for water treatment. Figure 4-1 is a schematic diagram of
the treatment process at Plant A.
During treatment, the influent water is split into four treat-
ment trains immediately prior to ozonation and the trains
are recombined prior to distribution. At the design flow-
rate, the treatment process takes approximately 40 min-
utes. Typically, it takes approximately 1 hour for raw
water to be processed. The treatment process consists
of the following major elements:
Screening. The raw water is passed through a
screen with a 2-inch mesh to remove debris.
Ozonation. Ceramic diffusers are used to feed
1.5 mg/L of ozone at the influent of the unit. There
Is approximately a 5-minute contact time. Ozona-
tion is used for disinfection and microflocculation
to improve filtration and control taste and odor.
The plant produces approximately 13,000 Ib/day
of ozone with six generators.
Rapid Mixing. 1 to 2 mg/L of ferric chloride and
1 to 5 mg/L of cationic polymer are mixed with the
water.
Flocculation. Flocculation occurs in three basins
placed in series with approximately 8.5 minutes of
contact time.
Filtration. Filtration is accomplished with a high-
rate filter (13.5 gpm/ft2). The filter media is anthra-
cite coal (1.5 mm effective size) and a thin layer of
pea gravel. Typically, backwashing occurs every 6
to 40 hours (average 20 hours) and the backwash
water is sent to settling ponds. Supernatant water
is fed into the water treatment plant influent. Back-
washing accounts for approximately 2% of plant
flow.
Chlorination. Chlorine is added during the treat-
ment process for disinfection. The treatment plant
chlorinates in order to maintain approximately
2 mg/L of residual chlorine.
4.2.2 Initial Source Water Sampling
Source water for Plant A is supplied primarily via an
aqueduct system that carries ground water and surface
water runoff from the Sierra Nevada Mountains. This
water is collected and stored in a series of eight reser-
voirs. The aqueduct is enclosed for 200 miles between
the last of the eight reservoirs and the water treatment
plant. Due in part to the high arsenic concentrations in
the source water, a water treatment facility was con-
structed in 1995 at the inlet of the last reservoir. This
plant doses 3 to 7 mg/L of ferric chloride and a cationic
Screening Ozonation
Raw
Water
Rapid Rapid
Mixing Mixing
Basin 1 Basin 2
D
Flocculation
Filtration
D
Cationic n_
PolymerLb-J
Recycle Backwash Water
Finished
Water
> Sludge to Hazardous Waste Facility
Figure 4-1. Schematic Diagram of Plant A Treatment Process
18
-------
polymer into the reservoir, which is used as a large
settling basin. The reservoir is relatively effective at re-
moving arsenic. The long-term average arsenic concen-
tration in the source water prior to entering the reservoir
is approximately 25 ug/L and the reservoir effluent has
an average arsenic concentration of 8 to 10ug!/L The
reservoir treatment plant is not considered part of Plant A
and is not included in the sampling phases of this study.
An initial site visit to Plant A was conducted February 3,
1998, during which time source water samples were col-
lected. The total arsenic concentration during the initial
sampling event was 10.4 ug/L. Particulate arsenic ac-
counted for 2.4 ug/L of the total arsenic concentration,
and soluble arsenic, primarily arsenate, accounted for
the remaining 8.0 ug/L of the total arsenic. The particu-
late arsenic is probably attached to the iron, which was
detected at a concentration of 170 ug/L. The As(V) con-
centration was 7.9 ug/L and the As(lll) concentration
was 0.1 ug/L, which is consistent with what would be
expected for a surface water source. Table 4-2 presents
the analytical results from the source water sampling.
Although the total arsenic in the source water at this plant
was below the desired concentration of 20 ug/L, it was
selected for incorporation into the preliminary sampling
and long-term evaluation phases. Selection of Plant A was
based on the very large size and the availability of re-
sources at the facility to conduct the long-term sampling.
4.2.3 Preliminary Sampling
During the preliminary sampling phase of this; study,
water samples were collected at three locations within
the treatment iplant: IN, PF, and AF. The IN samples
were collected from a tap located after initial screening
and after the supernatant from the sludge settling lagoons
had been recycled. The PF and AF samples were col-
lected from sample taps located on treatment train two of
the four parallel trains at Plant A. The PF sampling tap
was located after flocculation and just prior to filtration.
The AF sampling tap was located after filtration and prior
to final chlorine addition and distribution. Figure 4-2 is a
process flowchart for Plant A that shows sampling loca-
tions within thp treatment process and the associated
sample analyses performed at each location.
Alkalinity, turbidity, pH, total aluminum, total iron, total
manganese, TOC, and total arsenic analyses were per-
formed on samples collected each of the four weeks at
each of the three sampling locations. Arsenic speciation
was conducted once during the preliminary study on
samples collected from each sampling location. Soluble,
and particulate were determined as part of the arsenic
speciation, as; well as the species (arsenite and arse-
nate) making up the soluble fraction of the total arsenic.
Table 4-3 presents the results of the 4-week preliminary
sampling period.
Results from the preliminary sampling events indicated
that inlet total, arsenic concentrations ranged from ap-
proximately 12 to 17 ug/L. As found during the initial
source water sampling, the total arsenic in the source
water was primarily As(V) and contained only minor con-
centrations of ,As(lll) and particulate arsenic. As would
be expected, the species of arsenic did not vary during
the treatment process. The average total arsenic remov-
al by Plant A was approximately 48% during preliminary
Table 4-2. Source Water Analytical Results at Plant A (February 3, 1998)
Parameter
Alkalinity
Sulfate
Turbidity
pH
Hardness
Ca Hardness
Mg Hardness
Total Al
Total Fe
Total Mn
NO3-NO2 (N)
TOC
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Unit
mg/L"'
mg/L
NTU
mg/L""
mg/L"1
mg/L""
ug/L
ug/L
ug/L
mg/Llb)
mg/L
ug/L
ug/L
pg/L
ug/L
ug/L
Primary
Sample
98
44
0.67
8.1
104
74
29
<400
160
<20
0.12
1
11.1
7.3
3.8
ND
7.3
Duplicate
Sample
95
44:
0.68
8.1
93.5
65 ^
29
<400i
180;
<20:
0.13
2:
9.6
8.6
1.0
0.2
8.4
Average
Concentration
97
44
0.68
8.1
98.8
70
29
<400
170
<20
0.13
1.5
10.4
8.0
2.4
0.1
7.9
(a) As CaCO3.
(b) Combined NO3-N and NOa-N.
ND = not detected.
NTU = nephelometric turbidity units.
19
-------
WASTE LANDFILL
X">i As (total), water content,
(SSJ- ^- PH, TCLP metals
hi TT7TTT TIMf" TWMT4C! li
W olil 1JL1JNVJ JrAjINlJb t'
MONTHLY
As (dissolved and total),^. ( 4 J
PH \_y
As (total), As (III), As (V) ^
Treatment Train
Cationic Polymer fe
FeCl fc
iCV-lj f
DA- PI
As (total), As (HI), As(V) ^.
Backwash Water
Asftotan.AsfIin.AsW <*.
INFLUENT
^f
RECYCLE
' BACKWASH WATER
T
SCREENING
1
A
.._ _.^
1 2 3
1^ 1' ^
4
' ^r
OZONATION
'(f ^r i
' V
RAPID MIXING
BASIN #1
1
RAPID MIXING
BASIN #2
W ^ hw
r W W
V 1' 1
^
P
' T
FLOCCULATION
>h
IT \
v if *
Plant A
Coagulation/Filtration
Design Flow: 600 mgd
WEEKLY
As (total), Alkalinity, pH,
.--^. TOC, Turbidity, Total Al,
Total Fe, Total Mn
LEGEND
0 Water Sampling
Location
ฎ Sludge Sampling
Location
DA- Cl Disinfectant Addition
2 Pmnt
FILTRATION Unit Process
Chemical Added to
FeC13 Unit Process
As (total), Alkalinity, pH,
s k .w TOC, Turbidity, Total Al,
^ ^ ^ Total Fe, Total Mn
r ir
FILTRATION
u
As (total), Alkalinity, pH,
__w. TOC, Turbidity, Total Al,
NOTE:
Four treatment trains operate in
parallel at this plant These trains
split immediately before ozonation
and rccombine prior to distribution.
Sample locations 2 and 3 are located in
Treatment Train 2.
DA: C12
k-
i
ฑ_+
^
^
^
r ^
1
r
DISTRIBUTION
SYSTEM
Total Fe, Total Mn
Figure 4-2. Process Flow Diagram and Sampling Locations at Plant A
20
-------
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LL
Q.
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LL
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en
TJ-
*~
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CO T-
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t
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c^ "o> "CT
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s
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co O ซ- ซ
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As (particulate)
<
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n
-------
sampling, reducing the finished water total arsenic con-
centration to 6.1 to 9.5 ug/L. Plant A does not have a
sedimentation step following flocculation; therefore, the
majority of the arsenic removal occurred during filtration.
The As(V) attaches to iron floes and is then removed
during filtration, which is why the PF sampling location
consistently has higher total arsenic concentrations.
McNeill and Edwards (1997a) developed the following
simplified model for predicting arsenic removal at iron
and alum coagulation facilities based on raw water Fe
and Al concentrations:
Arsenic Sorbed(%)=100x
where K = 78 mM"
Kx[Fe + AI]mM
(l + Kx[Fe + AI]mM)
(1)
This model was based on data collected at over 14 full-
scale facilities, and was able to accurately predict arse-
nic removal within ฑ13% (90th percentile confidence
interval). Applying this model to the preliminary results
from Plant A, the predicted removal ranged between 51
and 62% compared to actual removals ranging from 43
to 52%. During the first sampling event, the actual and
predicted arsenic removal percentages were very close
(51% predicted and 52% actual). However, a 19% differ-
ence in arsenic removal was observed during the last
sampling event in which the calculated removal was 62%
and the actual removal was 43%. Estimated arsenic
removal percentages for the other two sampling events
were within ฑ13% of the actual removal observed. There-
fore, the simplified model appeared to approximate the
arsenic removal at Plant A fairly well.
Other water quality parameters were analyzed to support
understanding of the mechanisms of arsenic removal.
TOO and pH concentrations were relatively constant
throughout the treatment process during the preliminary
sampling phase. Also, the pH was approximately 8.0 and
in the range where no effect on arsenic removal efficien-
cy using iron (III) salts has been observed in previous
studies (Sorg and Logsdon, 1978; Sorg, 1993; Hering et
al., 1996).
A slight decrease in alkalinity was observed after the
addition of the ferric chloride coagulant (i.e., at the PF
sampling location). This decrease in alkalinity is a result
of a chemical reaction with ferric chloride:
2FeCI3 + 3Ca(HCO3)2 -> 2Fe(OH)3i
3CaCI2 + 6CO2
(2)
Total aluminum concentrations were below detection
limits at all three locations during each sampling event
and were not considered to play a role in arsenic re-
moval; however, the detection limits were relatively high
(400 |jg/L). Total manganese concentrations ranged from
<20 to 70 ug/L in the inlet and <20 to 50 ug/L in the
outlet. The total iron concentrations averaged 293 ug/L
at the inlet, 980 ug/L at the prefiltration sampling loca-
tion, and 63 ug/L at the after-filtration sampling location.
The increase at the prefiltration location is due to the
addition of FeCI3 as a coagulant. The iron then is re-
moved in the filters. It appears that the primary arsenic
removal mechanism at Plant A is adsorption and copre-
cipitation of As(V) with the iron floes.
Based on the results of the preliminary sampling effort,
only minor changes were made to the approach for the
long-term evaluation. Sampling locations and primary
analytes remained unchanged. However, aluminum, iron,
and manganese analysis was modified to achieve lower
detection limits by using ICP-MS. Also, it was deter-
mined that part of the sample in bottle B from the arsenic
speciation kits would be used to determine dissolved
aluminum, iron, and manganese concentrations.
4.2.4 Long-Term Sampling
Long-term sampling and analysis consisted of 49 weeks
of sampling with 12 arsenic speciation sampling events.
During the long-term sampling phase of this study, water
samples were collected at the same three locations that
were used during the preliminary sampling phase: IN,
PF, and AF. Alkalinity, turbidity, pH, total aluminum, total
iron, total manganese, TOG, and total arsenic analysis
was performed on samples collected each week. Arsenic
speciation sampling was conducted 12 times during the
long-term sampling phase on samples collected from
each sampling location. Dissolved aluminum, iron, and
manganese concentrations at each sampling location
were determined monthly using a sample from bottle B
of the arsenic speciation kits. Additionally, residual sam-
pling was performed during this phase and consisted of
collection and analysis of recycle supernatant water and
sludge from the settling pond. The following subsections
summarize the analytical results for arsenic, other water
quality parameters, and residuals. Figure 4-2 is a pro-
cess flow diagram for Plant A that indicates sampling
locations during the long-term evaluation and the analy-
ses performed on samples from each location.
4.2.4.1 Arsenic
Table 4-4 provides a summary of the arsenic analytical
results collected at the three treatment process locations
at Plant A. Total arsenic concentrations at the inlet
ranged from 2.6 ug/L to 12.1 ug/L with an average con-
centration of 7.5 ug/L. These concentrations are slightly
lower than what was observed during the initial source
water and preliminary sampling phases of this study.
22
-------
Table 4-4. Summary of Arsenic Analytical Results at Plant A (June 1998-June 1999)
Parameter
As (total)
As (total
soluble)
As
(particulate)
As(lll)
As(V)
Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
M9/L
Mg/L
M9/L
Pg/L
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
.pg/L
pg/L
pg/L
pg/L
Number of
Samples
49
49
48
VI
12!
12!
12!
12!
12!
12!
12!
12!
12!
12!
12!
Minimum
Concentration
2.6
2.0
0.8
5.1
2.7
2.0
<0.1
1.7
<0.1
0.3
<0.1
<0.1
4.8
2.2
1.6
Maximum
Concentration
12.1
23.4
6.0
10.9
6.0
! 4.8
1.9
7.8
0.5
2.0
2.1
1.9
10.2
5.4
: 4.3
Average
Concentration
7.5
8.7
3.5
7.7
4.3
3.5
0.5
4.3
0.2
0.7
0.6
0.6
6.9
3.6
3.0
Standard
Deviation
2.1
3.9
1.1
1.7
1.1
0.9
0.6
1.8
0.2
0.5
0.6
0.5
1.7
0.9
0.7
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
These results are due to a general trend of slightly high-
er arsenic concentrations that occur seasonally during
the months of February through July. Total arsenic con-
centrations at the PF sampling location ranged from 2.0
to 23.4 ug/L, with an average of 8.7 ug/L. Therefore, in
general, no reduction of arsenic was observed between
the inlet and prefiltration sampling locations. In fact, the
data indicated that a slight increase in total arsenic con-
centration occurred due to the formation of iron floes which
sorbed the arsenate. The floes accumulated just prior to
the filtration step where the PF samples were collected.
Samples collected at the after-filtration location con-
tained total arsenic concentrations ranging from 0.8 ug/L
to 6.0 ug/L with an average concentration of 3.5 ug/L.
The average removal percentage of total arsenic be-
tween the inlet and after-filtration sampling locations was
53%. The average arsenic removal predicted by the
McNeill and Edwards (1997a) sorption model was 43%,
which is within the 90th percentile confidence interval of
the model. However, individual sampling events showed
differences in actual and predicted arsenic removals as
high as 63% and the average difference was approxi-
mately 20%, which is outside of the 90th percentile confi-
dence interval for the model. The discrepancies between
the actual and predicted values may be due to tempera-
ture and competition for sorption sites by natural organic
matter (McNeill and Edwards, 1997a). Also, the low
arsenic concentration in the source water (average
7.5 ug/L) likely contributed to the discrepancy between
the predicted and actual removal efficiencies. However,
it appears that the difference is not a result of iron floe
passing through the filter because the particulate arsenic
and total iron concentrations at the outlet are very low.
Figure 4-3 is a graph showing the total arsenic concen-
tration recorded at each sampling location throughout
the study, as well as removal percentages calculated for
each sampling 'event.
Particulate arsenic concentrations averaged 0.5 ug/L at
the inlet, 4.3 ug/L at the prefiltration sampling location,
and 0.2 ug/L at the after-filtration sampling location. The
increase of particulate arsenic at the prefiltration sam-
pling location is due to sorption and coprecipitation of
arsenic on/with the iron floes formed. This observation is
supported by the decrease of particulate arsenic in the
after-filtration sampling location.
As(lll) and As(V) make up the soluble portion of the total
arsenic concentration. Throughout the duration of the
study and at each sampling location, As(V) made up the
majority of the soluble arsenic. As(lll) concentrations
averaged 0.7 ug/L at the inlet, 0.6 ug/L at the prefiltration
location, and 0.6 ug/L at the after-filtration location, indi-
cating that As(lll) was not removed by the treatment pro-
cess. Although the As(lll) concentrations were low, no
apparent conversion to As(V) was observed after ozona-
tion. Average As(V) concentrations were 6.9 ug/L at the
inlet, 3.6 ug/L at the prefiltration location, and 3.0 ug/L at
the after-filtration location. The As(V) concentration de-
creased at the prefiltration location due to coprecipita-
tion/adsorption of the arsenic with iron floes. This result
correlates with the increase in particulate arsenic at this
same location. The arsenic that was not removed with
the coagulant passes through the system. Figure 4-4
provides charts showing the fractions of the total arsenic
concentration made up by particulate arsenic, As(lll),
and As(V) throughout the long-term evaluation.
The Plant A water treatment system was able to con-
sistently remove arsenic to low levels (i.e., average
treated water total arsenic concentration is 3.5 ug/L).
23
-------
90%
-10%
6/4/98 7/24/98 9/12/98 11/1/98 12/21/98 2/9/99 3/31/99 5/20/99 7/9/99
Date
Figure 4-3. Total Arsenic Analytical Results During Long-Term Sampling at Plant A
The primary arsenic removal mechanism appears to be
coprecipitation/adsorption with iron floes followed by filtra-
tion. The simplified sorption model developed by McNeill
and Edwards (1997a) appears to approximate the arse-
nic removal process at Plant A reasonably well, although
discrepancies were noted.
4.2.4.2 Other Water Quality Parameters
In addition to arsenic analysis, other water quality param-
eters were analyzed to provide insight into the chemical
processes occurring at the treatment facility. Table 4-5
summarizes the analytical results for several water qual-
ity parameters obtained during the long-term sampling at
Plant A.
Alkalinity concentrations ranged from 45 mg/L to 112 mg/L
(as CaCO3) in the inlet with an average of 89 mg/L. The
analytical data indicated seasonal variations in alkalinity
concentrations, with a dip occurring during July and
August. This dip correlated with the snow melt in the
Sierra Nevada mountains, which resulted in a higher
percentage of the source water coming from lower-alka-
linity melted snow. However, these data did not appear
to correlate with arsenic analytical results or removal effi-
ciencies at Plant A. Figure 4-5 plots the inlet alkalinity,
turbidity, pH, and TOG concentrations throughout the
duration of the study.
During long-term sampling, turbidity concentrations aver-
aged 1.2 NTU at the inlet, 1.8 NTU at the prefiltration
location, and <0.1 NTU at the after-filtration location. As
seen in Figure 4-5, spikes in the inlet turbidity concentra-
tions were observed during the study and are most likely
due to precipitation events that increase suspended sol-
ids in the source water. The ferric chloride dosages are
adjusted to account for the varying turbidity concentra-
tions. The data show that Plant A effectively removes tur-
bidity from the source water, although no correlation was
observed regarding arsenic removal efficiency.
The average pH was 8.0 at the inlet, 7.9 just prior to
filtration, and 7.8 in the finished water. These pH values
are in the range (pH 5.5 to 8.5) where arsenic removal
efficiency by iron oxides is not affected (Sorg, 1993). On
March 24, 1999, a pH of 5.2 was reported; however, this
figure is considered to be an outlier because plant oper-
ational data did not indicate any change in pH. TOC con-
centrations also were relatively constant, with averages of
2.4 mg/L, 2.7 mg/L, and 2.4 mg/L, at the inlet, prefiltration,
and after-filtration sampling locations, respectively. TOC
does not appear to impact arsenic removal efficiency.
Total iron concentrations at the inlet sampling location
ranged from <30 to 767 ug/L and averaged 146 ug/L. At
the prefiltration sampling location, total iron concentrations
ranged from <30 to 2,646 ug/L and averaged 642 ug/L.
24
-------
Inlet
14
12 .
- 10
o 4.
2 -
14
Prefiltration
12 -
T 10 .
5 4
2 -
*
After Filtration
14
12
3- 10
T 8
_o
ซ
ฃ 6
O
o
I 4
2
0
-\>
Q
Figure 4-4. Arsenic Form and Species Analytical Results During Long-Term Sampling at Plant A
25
-------
Table 4-5. Summary of Water Quality Parameter Analytical Results at Plant A (June 1998-June 1999)
Parameter
Alkalinity
Turbidity
pH
TOC
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
;,'
Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiitration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
mg/L
mg/L
mg/L
NTU
NTU
NTU
mg/L
mg/L
mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
MQ/L
Mg/L
Mg/L
(jg/L
Mg/L
pg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Number of
Samples
48
48
48
48
48
48
48
48
48
47
48
48
49
49
49
49
49
49
49
49
49
12
12
12
12
12
12
12
12
12
Minimum
Concentration
45
43
42
0.3
0.4
<0.1
5.2
7.5
7.4
1.5
<1.0
1.5
<11
18.2
<11
<30
<30
<30
4.4
8.9
<0.5
<11
<11
<11
<30
<30
<30
1.1
1.4
<0.5
Maximum
Concentration
112
111
109
5.5
18.5
0.2
8.3
8.1
8.0
4.8
12.0
7.4
717
246
39
767
2,646
63.8
112
85.5
45.4
22.6
<11
18
45.7
<30
<30
10.8
69.7
5.8
Average
Concentration
89
88
87
1.2
1.8
<0.1
8.0
7.9
7.8
2.4
2.7
2.4
68
64
12
146
642
<30
20.9
27.1
4.7
<11
<11
<11
<30
<30
<30
3.1
8.7
2.3
Standard
Deviation
20.7
20.6
20.5
1.0
2.7
0.04
0.4
0.1
0.2
0.6
1.5
0.9
104.2
48.8
7.6
175.1
474.5
14'7
20.0
17.0
7.2
4.9
NA
3.7
8.9
NA
NA
2.6
19.2
2.3
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
The total iron concentration increased at the prefiltration
location due to the addition of FeCI3 as a coagulant. The
average total iron concentration at the after-filtration
sampling location was <30 ug/L. Also, average dissolved
iron cqncentrations were below the detection limit at the
inlet, prefiltration, and after-filtration sampling locations.
As stated previously, iron is the key factor in arsenic
removal at Plant A. It is believed that the majority of the
arsenic removal is through adsorption and coprecipita-
tion of As(V) with iron hydroxides.
Total aluminum concentrations averaged 68 ug/L at the
Inlet, 64 ug/L at the prefiitration location, and 12 pg/L at
the after-filtration location. The average dissolved alum-
inum concentration at all three locations was less than
the detection limit. It did not appear that coprecipitation
with aluminum, hydroxide was a significant factor in the
removal of arsenic at Plant A, because minor concentra-
tions were present and almost all of the aluminum was in
the paniculate form at the inlet.
Total manganese concentrations averaged 20.9 ug/L,
27.1 ug/L, and 4.7 ug/L, at the inlet, prefiltration, and after-
filtration sampling locations, respectively. Average dis-
solved manganese concentrations were 3.1 ug/L at the
inlet, 8.7 ug/L at the prefiltration location, and 2.3 ug/L at
the after-filtration location.
4.2.4.3 Recycle Supernatant Water
Approximately 2% of the total flow at Plant A is used for
backwashing filters. The filter backwash water then is
sent to a sludge settling pond and the supernatant is
recycled. The supernatant water is added continuously
to the source water and processed at the facility. Super-
natant samples were collected from a sample tap in the
piping that transports the water from the sludge settling
pond to the source water inlet. Results of supernatant
sampling are summarized in Table 4-6.
The soluble arsenic concentrations are approximately
equal to those measured in the source water; however,
the particulate arsenic is approximately 3.0 ug/L higher
on average. This result would be expected because the
backwash water contains some unsettled iron solids, which
most likely contain sorbed arsenic. The low dissolved iron
concentrations observed during the study support this
assumption. Based on these results, it does not appear
26
it t
-------
ฃ
1 3
- 100
80
I
60 c
0
- 40
. 20
-Turbidity (NTU)
-pH (units)
-TOG (mg/L)
-Alkalinity (mg/L as CaCO3)
6/4/98 7/24/98 9/12/98 11/1/98 12/21/98 2/9/99 3/31/99 5/20/99 7/9/99
Date
Figure 4-5. Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at Plant A
that the recycle backwash water would impact the treat-
ment process either positively or negatively.
4.2.4.4 Sludge
Sludge is generated at Plant A from backwashing the
anthracite coal/pea gravel filters. Typically, backwashing
occurs every 6 to 40 hours (average 20 hours) and the
backwash water is sent to settling ponds. Supernatant
water from the settling ponds is recycled into plant influent.
Approximately 2% of plant flow is used for backwashing.
Approximately once per year, or as required, the settling
ponds are drained and the sludge is removed. Approxi-
mately 18,000 tons of sludge are removed per year. The
sludge is considered California hazardous waste due to
elevated concentrations of arsenic and copper based on
exceedances of regulatory levels for the soluble thresh-
old limit concentration (STLC). Total arsenic and TCLP
results have not exceeded regulatory levels for classi-
fication as California hazardous waste. Table 4-7 con-
tains analytical results from sludge sampling conducted
during three sampling events at Plant A in October 1996,
March 1997, and May 1997.
During the long-term evaluation phase, sludge samples
were collected on December 2, 1998, from three locations
within a dewatered sludge pond. These sludge samples
were analyzed,for pH, percent moisture, total arsenic, and
total iron. Also, a TCLP test was performed on each
sample to determine the quantities of leachable arsenic,
Table 4-6. Summary of Analytical Results from Recycle Backwash Water Samples at Plant A
(November 11, 1998-June 16,1999)
Parameter
As (total)
As (soluble)
As (particulate)
PH
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Number of
Units Sample Events
pg/L
pg/L
M9/U
ug/L
M9/L
M9/L
P9/L
pg/L
pg/L
8
8
8
7
8
8
8
8
8
8
Minimum
Concentration
3.7
3.8
<0.1
7.6
<11
174
52.8
<11
<30
33.2
Maximum
Concentration :
19.7
10.9
11.7
7.9
113
1367
572
<11
127
235
Average
Concentration
10.2
7.1
3.2
7.8
47
535
169
<11
37.9
78.3
Standard
Deviation
5.1
2.6
4.1
0.1
44
420
174
NA
39.3
67.0
27
-------
Table 4-7. Previous Analytical Results of Sludge Sampling at Plant A (1996-1997)
Analyte
Description
October 1996 March 1997 May 1997
Total Arsenic
Arsenic-STLC
Arsenic-TCLP
Number of samples
Minimum concentration (mg/kg)
Maximum concentration (mg/kg)
80% UCL concentration (mg/kg)
Regulatory level (mg/kg)
Number of samples
Minimum concentration (mg/L)
Maximum concentration (mg/L)
80% UCL concentration (mg/L)
Regulatory level (mg/L)
Number of samples
Minimum concentration (mg/L)
Maximum concentration (mg/L)
80% UCL concentration (mg/L)
Regulatory level (mg/L)
10
110
740
418
500
10
4.1
37
22
5
10
<0.2
<0.2
NA
5
10
73
370
265
500
10
5
21
15
5
10
<0.2
0.3
NA
5
10
110
210
180
500
10
9.5
15
13
5
10
<0.2
0.3
NA
5
UCL = upper confidence level.
barium, cadmium, chromium, lead, mercury.selenium, and
silver. The sample collected from location 2 did not have
the same appearance as the samples from locations 1
and 3. It was reported to look more like soil than dried
sludge. This difference in appearance probably accounts
for the differences in measured arsenic and iron concen-
trations between the location 2 sample and the samples
from locations 1 and 3. Assuming that the samples col-
lected from locations 1 and 3 are more representative of
the sludge produced by Plant A, total arsenic concen-
trations were 806 and 880 mg/kg dry, respectively, and
total iron concentrations were 83,200 and 95,000 mg/kg
dry, respectively. These total arsenic concentrations ex-
ceed the regulatory levels for total arsenic in California,
which would classify this sludge as hazardous waste.
Arsenic was detected in one sample leachate at a con-
centration of 0.106 mg/L, which was well below the regu-
latory limit of 5 mg/L. Table 4-8 presents the results of
sludge analysis at each of the three sampling locations.
4.3 Plant B
Water and residual samples were collected and analyzed
at Plant B, a coagulation/filtration plant, during three
phases of the study: source water sampling, preliminary
sampling, and long-term evaluation. Source water sam-
pling at Plants was performed in February 1998. Pre-
liminary sampling consisted of weekly water sampling for
a 4-week period in April/May 1998 and was designed to
determine if the sampling locations and proposed water
quality analysis were appropriate for the third phase, long-
term evaluation. The third phase was initiated in June
1998 and continued through June 1999. Arsenic specia-
tion sampling was conducted every fourth week. The third
phase of this study also included residual sample collec-
tion and analysis. Supernatant water samples from the
settling tank were collected monthly beginning in Novem-
ber 1998, and three sludge samples were collected during
a single sampling event from a dewatered sludge lagoon.
Table 4-8. Analytical Results of Sludge Sampling at Plant A (December 2,1998)
Parameter
Unit
DL
Location 1
Location 2
Location 3
As-TCLP
Ba-TCLP
Cd-TCLP
Cr-TCLP
Pb-TCLP
Hg-TCLP
Se-TCLP
Ag-TCLP
TCLP extraction
PH
Percent moisture
Total As
Total Fe
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NA
%
mg/kg, dry
mg/kg, dry
0.05
1.0
0.020
0.030
0.50
0.0002
0.05
0.020
NA
0.1
2.0
1,370
0.106
1.1
<0.020
<0.030
<0.50
<0.0002
<0.050
<0.020
Complete
7.0
31.6
806
83,200
<0.05
1.1
<0.020
<0.030
<0.50
<6.0002
<0.050
<0.020
Complete
8.1
14.6
9.0""
17,600
<0.05
<1.0
<0.020
<0.030
<0.50
<0.0002
<0.050
<0.020
Complete
7.2
" 38.6
880
95,000
(a) Confirmed by sample re-analysis. The sample looked like soil instead of dry sludge.
DL = Detection limit.
28
-------
4.3.1 Plant B Description
Plant B is used to treat surface water for a population of
approximately 65,000. The plant processes 6 to 8 mgd
during the winter months and 30 to 35 mgd during the
summer. The design flowrate is 62.5 mgd. The plant uti-
lizes coagulation, sedimentation, and filtration for water
treatment. Figure 4-6 is a schematic diagram of the treat-
ment process used at Plant B.
The treatment process at Plant B consists of the follow-
ing major elements:
Screening. Screening is required to remove
debris from the raw water at the river intake.
Pre-Chlorination. Approximately 3 to 4 mg/L of
chlorine is added to the raw water for disinfection
and to provide residual chlorine for the distribution
system.
Rapid Mixing. Depending on influent turbidity,
25 to 30 mg/L of alum is added to the water. Also,
0.75 mg/L Cat Floc-TL polymer is used when
water temperature is less than 10ฐC, typically
October through April. Jar testing conducted by
the treatment plant was used to develop relation-
ships for estimating alum dosage based on
influent turbidity.
Flocculation. Flocculation of alum hydroxide and
various contaminants, including arsenic, occurs
during this treatment process. During late
summer, powdered activated carbon (PAC) may
be added for taste and odor control.
ซ Sedimentation. Sedimentation of floes occurs in
primary and secondary clarifiers.
Filtration. Additional solids removal is accom-
plished through filtration. Filtering is accomplished
with a dual media consisting of anthracite and
sand. Backwashing occurs approximately every
50 hours.
Clean/veil Storage. Ammonia is added prior to
clean/veil storage to form monochloramine. No
posttreatment chlorination is performed.
Backwash. Backwashing occurs approximately
every 50 hours. The sludge eventually is sent to a
landfill and the supernatant water from the sludge
lagoon is discharged to the Missouri River under a
state permit.
4.3.2 Initial Source Water Sampling
Plants influent water is supplied from the Missouri
River. Based on discussions with plant personnel, the
turbidity ranges from 2 to 3 NTU in the winter and be-
tween 10 and 100 NTU during the spring and summer
due to snow melt and rain. The primary source of arse-
nic in the source water is believed to come from the
Yellowstone Basin that drains into the Madison River,
the largest tributary of the Missouri River. Historically,
Raw Water-
from
River
Rapid Mixing Flocculation
Sedimentation
Filtration
AI2(S04)3|-L,
[Alum] Lb-1
PolymerPT_
Sanitary.^.
Sewer
uuy
1
I
Settling
Tank
Backwash W
ater
Cle
Stc
Supernatant Water
Discharged to the River
Sludge Lagoon
Explanation
PAC Powdered Activated Carbon
(Only used during summer for taste and odor control)
afHj ^
Finished
Water
> Sludge to Landfill
Figure 4-6. Schematic Diagram, Plant B
29
-------
arsenic concentrations in the source water have ranged
from 16 to 25 ug/L.
An initial site visit tp Plant B was conducted on February
5, 1998, during which time source water samples were
collected. During this sampling event, samples were col-
lected and analyzed for arsenic (total, particulate, soluble,
AsfJII], As[V]) and various other water quality parameters
that may affect arsenic removal. Table 4-9 presents the
analytical results from the source water sampling. The
total arsenic concentration in the source water averaged
21.2 ug/L. Particulate arsenic averaged 1.4 ug/L of the
total, and all of the soluble arsenic was As(V). The inlet
iron concentration averaged 2,790 ug/L, which was rela-
tively high and did not correlate well with the total iron
data collected during the preliminary sampling and long-
term evaluation phases. Aluminum concentrations were
less than the detection limit, and manganese concen-
trations were 30 ug/L.
Alkalinity concentrations averaged 122 mg/L (as CaCO3)
and total hardness concentrations averaged 281.5 mg/L
(as CaCOa). Therefore, the source water would be clas-
sified as hard. Based on discussions with plant person-
nel, turbidity concentrations are typically in the range of
2 to 3 NJU in the Winter, Consistent with this information,
turbidity concentrations were relatively low during the
source water sampling event conducted in February, aver-
aging 1.1 NTU. The pH averaged 8.2, which is relatively
high for effective arsenic removal using alum (Sorg and
Logsdon, 1978; Sorg, 1993).
4.3.3 Preliminary Sampling
Water samples collected during the preliminary sampling
phase of this study were taken at three locations within
the treatment plant: (1) the IN; (2) PF; and (3) AF. The
IN and PF sampling locations were open channels trans-
porting the raw and partially treated water to the various
treatment processes in the plant. Therefore, a scoop
was used to take grab samples at IN and PF sampling
locations. The IN sample was collected from a channel
immediately following initial screening. The PF sample
was collected from the channel located after rapid mix-
ing, flocculation and sedimentation. A sink facet located
in the plant was used as the AF sampling location and
represents the finished water entering the distribution
system. Figure 4-7 is a process flow diagram for Plant B
that shows sampling locations used during the prelimi-
nary sampling, as well as the analyses performed on
samples collected from each location.
Alkalinity, turbidity, pH, total aluminum, total iron, total
manganese, TOC, and total arsenic analysis was per-
formed on all water samples collected at Plant B. Arse-
nic speciation sampling was conducted at each sampling
location once during the preliminary study. Arsenic form
(soluble and particulate) and species (arsenate and
arsenite) were determined as part of the arsenic specia-
tion. Table 4-10 presents the results of the 4-week pre-
liminary sampling period.
Results from the preliminary sampling events indicated
that inlet total arsenic concentrations ranged from ap-
proximately 20.9 to 23.3 ug/L. The total arsenic in the
source water was primarily As(V) and contained only mi-
nor concentrations of As(lll) and particulate arsenic. As
would be expected, the species of arsenic did not vary
significantly during the treatment process. The average
total arsenic removal by Plant B was approximately 86%
during preliminary sampling. In general, the majority of the
arsenic removal occurred during sedimentation (average
Table 4-9. Source Water Analytical Results at Plant B (February 5,1998)
Parameter
Alkalinity
Sulfate
Turbidity
PH
Hardness
Ca Hardness
Mg Hardness
Total Al
Total Fe
Total Mn
NCy-NO2 (N)
TOC
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
(a) AsCaCO3.
Units
mg/L("
mg/L
NTU
mg/Lw
mg/L1"
mg/L"1
Mg/L
Mg/L
Mg/L
mg/L1"
mg/L
Mg/L
ug/L
M9/L
M9/L
Mg/L
Primary
Sample
122
38
1.08
8.2
286
147
138
<400
2,780
30
0.23
3
22.5
20.3
2.2
<0.1
20.3
Duplicate
Sample
122
37
1.11
8.2
277
140
138
<400
2,800
30
0.22
3
20.0
19.3
0.7
<0.1
19.3
Average
Concentration
122
37.5
1.095
8.2
281.5
143.5
138
<400
2,790
30
0.22
3
21.2
19.8
1.4
<0.1
19.8
(b) Combined NO3-N and NO2-N.
30
-------
MONTHLY
As (total), As (III), As (V)
As (total), Water Content,
pH, TCLP metals
As (dissolved and total), ^-
pH
SUPERNATANT WATER
DISCHARGED TO
MISSOURI RIVER
SETTLING
TANK
SETTLING
LAGOON
SLUDGE SENT TO
LANDFILL
As (total), As (III), As (V)
Backwash Water
As (total), As (III), As (V)
NH3
FLAPID MIXING
BASIN
FLOCCULATION
PRIMARY
CLARIFIER (5)
SECONDARY
CLARIFIER (2)
FILTRATION
DISTRIBUTION
SYSTEM
Plant B
Coagulation/Filtration
Design Flow: 62.5 mgd
WEEKLY
As (total), Alkalinity, pH,
TOC, Turbidity, Total Al,
Total Fe, Total Mn
A12(S04)3
Cat Floc-TL Polymer
LEGEND
o
A12(S04)3
Water Sampling
Location
Sludge Sampling
Location
Disinfectant Addition
Point
Unit Process
Chemical Added to
Unit Process
As (total), Alkalinity, pH,
TOC, Turbidity, Total Al,
Total Fe, Total Mn
As (total), Alkalinity, pH,
TOC, Turbidity, Total Al,
Total Fe, Total Mn
Figure 4-7. Process Flow Diagram and Sampling Locations at Plant B
31
-------
CO
2L c
^ o
> "ni
& IS
co
CM
Q.
D.
I-
0)
JQ
.OS
CO O)
CO
-------
75%). Additional arsenic removal occurred during filtra-
tion to achieve the 86% average removal, leaving only
2.4 to 4.2 ug/L in the finished water.
Very good correlation with the sorption model proposed
by McNeill and Edwards (1997a) was observed. Pre-
dicted arsenic removal ranged between 89 and 91%,
while actual removals ranged between 82 and 89%. The
largest deviation between the predicted and actual arse-
nic removal was 10%, which is within the 90th percentile
confidence interval of the model. Therefore, this simpli-
fied sorption model appeared to approximate the system
performance and was used in evaluating long-term data.
Other water quality parameters were analyzed to support
understanding of the mechanisms of arsenic removal.
TOC concentrations were relatively constant (i.e., 3 mg/L)
throughout the treatment process, indicating no signifi-
cant TOC removal by the plant. Similar to Plant A, the
lack of TOC removal does not appear to impact arsenic
removal.
During alum coagulation, the alum reacts with natural
alkalinity to form aluminum hydroxide:
AI2(SO>14.3H20 + Ca(HCO3) -> 2AI(OH)3
+ 3CaSO4 + 14.3H2O +6CO2
(3)
Therefore, alkalinity concentrations and pH values de-
creased between the inlet and prefiltration sampling
locations. Average alkalinity concentrations decreased
from 132 to 111 mg/L (as CaCO3) and average pH val-
ues decreased from 8.6 to 7.5. The alkalinity and pH then
remained constant between the prefiltration and after-
filtration sampling locations. Turbidity concentrations aver-
aged 5.6 NTU during the preliminary sampling phase.
These turbidity values are almost 6 times higher than the
values observed during the preliminary sampling event;
however, this would be expected due to snow melt and
precipitation during the spring months.
Total aluminum concentrations ranged between <400
and 680 ug/L in the inlet and between 500 and 600 ug/L
in the prefiltration location. Total aluminum was less than
detection during all four sampling events at the after-
filtration sampling location. An increase in aluminum
concentration due to the addition of alum is not observed
at the prefiltration sampling location because it is located
after sedimentation. However, based on plant alum dos-
age data, the calculated aluminum concentration avail-
able for coagulation ranged between 2.5 and 4..1 mg/L.
Total manganese concentrations ranged from 40 to
90 ug/L in the inlet and <20 to 50 ug/L in the prefiltration
and after-filtration locations. The total iron concentrations
averaged 460 ug/L at the inlet, 44 ug/L at the prefiltration
sampling location, and <30 ug/L at the after-filtration
sampling location. The inlet iron concentrations were sig-
nificantly lower than the concentration obtained during
the source water sampling event and consistent with the
concentrations: observed during the long-term evalua-
tion phase. It appears that arsenic removal is primarily
achieved through adsorption and coprecipitation of As(V)
with the aluminum floes formed from the alum coagulant
and the iron in the source water.
Based on the results of the preliminary sampling effort,
only minor changes were made to the approach for the
long-term evaluation. As with Plant A, sampling locations
and primary analytes remained unchanged; however,
aluminum, iron, and manganese analyses were modified
to ICP-MS. Also, part of the sample in bottle B from the
arsenic speciaiion kits was used to determine dissolved
aluminum, iron, and manganese concentrations.
4.3.4 Long-Term Sampling
Long-term sampling and analysis consisted of 49 weeks
of water sampling at the same three locations used dur-
ing the preliminary sampling phase. All weekly samples
were analyzed for alkalinity, turbidity, pH, total alumi-
num, total iron, total manganese, TOC, and total arsenic.
Arsenic speciation sampling was conducted at each sam-
pling location ;12 times during the long-term sampling
phase on samples collected from each sampling location
and included determination of dissolved aluminum, iron,
and manganese concentrations. Supernatant discharge
water and sludge sampling and analysis also was per-
formed during this phase. The following subsections sum-
marize the arsenic, other water quality parameters, and
residuals analytical results.
4.3.4.1 Arsenic
Table 4-11 provides a summary of the arsenic analytical
results collected at the three sampling locations. Total
arsenic concentrations at the inlet ranged from 15 to
23.9 ug/L with, an average concentration of 19.1 ug/L.
These arsenic concentrations correspond well with the
historical data collected by the plant where total arsenic
concentrations have ranged from 16 to 25 ug/L. Total
arsenic concentrations at the prefiltration location ranged
from 3.0 to 15.5 ug/L with an average of 6.4 ug/L. There-
fore, an average arsenic removal rate of 66% occurred
prior to filtration in the sedimentation basins. Samples
collected after-filtration location contained total arsenic
concentrations ranging from 1.5 to 11.8 ug/L with an
average concentration of 4.0 ug/L. The average removal
percentage of'total arsenic (comparing raw water and
finished water concentrations) was 79%. These removal
percentages were calculated based on an average of all
total arsenic data collected during the long-term evalu-
ation, including the 6-week period when a polyaluminum
33
-------
': ":i;
Table 4-11.
IfUII, ' , '
Summary of Arsenic
, ,jj.j ni i "
^nj,,,,,
Parameter Sample Location
As (total)
As
(total soluble)
As
(particulate)
As(lll)
As{V)
..,i,,i
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
' Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Analytical
Units
pg/L
pg/L
P9/L
Pg/L
PS/L
Pg/L
pg/L
pg/L
pg/L
Pg/L
pg/L
pg/L
pg/t-
M9/L
P9/L
Results at Plant
,i
Number of
Samples
49
49
49
12
12
12
12
12
12
12
12
12
12
12
12
" ,
111 ' ':
"
,l! !' i ' II'!1
-il !'!'
B (June 1998-June 1999)
Minimum
Concentration
15
3.0
1.5
18.3
2.1
2.2
<0.1
0.6
<0.1
0.1
<0.1
<0.1
17.9
1.8
1.9
E(, ' ,'!] i
Maximum
Concentration
23.9
15.5
11.8
23.0
12.1
12.5
0.6
4.5
0.3
i ' !
1.2
1.2
0.8
21.8
11.8
12.1
Average
Concentration
19.1
6.4
4.0
20.3
4.3
4.6
0.2
2.6
<0.1
0.6
0.4
0.4
19.7
3.9
4.2
1 " '] *!:'" !;
Standard
Deviation
2.4
2.7
2.7
1.3 "
3.1
3.2
0.2
1.2
0.1
1 . , t si
0.3
0.3
0.2
1.2
3.2
3.3
pne-hajf of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculation.
chloride coagulant was used instead of alum. The re-
moval efficiencies observed during the long-term evalu-
ation correspond well with the removal percentages ob-
served during the preliminary sampling phase (75% and
86% arsenic removal achieved at the PF and AF sam-
pling locations, respectively). Figure 4-8 is a graph
showing the total arsenic concentration recorded at each
sampling location throughout the study.
iij ,., '(i(i ' I'jjjii;1,! . , , '. . " :
Particulate arsenic concentrations averaged 0.2 ug/L at
the inlet, 2.6 ug/L at the prefiltration sampling location,
and <0.1 ug/L at the after-filtration sampling location. The
increase of particulate arsenic at the prefiltration sam-
pling location was attributed to the sorption and copre-
clpitation of the arsenic and the aluminum floes. The de-
crease of particulate arsenic in the after-filtration sam-
pling location supports this observation. The low levels of
particuiate arsenic at the after-filtration location indicated
that the system effectively removes arsenic sorbed to
metal floes.
As(lll) and As(V) make up the soluble portion of the total
arsenic concentration. Throughout the duration of the
study and at each 'sampling location, As(V) made up the
majority of the soluble arsenic, averaging 97, 90, and
91% at the IN, PF, and AF sampling locations, respec-
tively. As(lll) concentrations averaged 0.6 ug/L at the
inlet, 0.4 ug/L at the prefiltration location, and 0.4 ug/L at
the after-filtration location. The treatment process re-
moved approximately 33% of the inlet As(lll). This re-
moval was probably due to conversion of As(lll) to As(V)
during chlorination, followed by sorption/occlusion with
alum floes, sedimentation, and filtration. Average As(V)
concentrations were 19.7 ug/L at the inlet, 3.9 ug/L at
the prefiltration location, and 4.2 ug/L at the after-filtration
location. The As(V) concentration decreased at the prefil-
tration location due to adsorption and coprecipitatiori of
the arsenic with the aluminum floes in the sedimentation
basins. This result correlated with the increase In par-
ticulate arsenic at this same location. Figure 4-9 shows
the fractions of the total arsenic concentration made up
of particulate arsenic, As(lll), and As(V).
As seen in Figure 4-9, a significant decrease in arsenic
removal efficiency was observed beginning October 29,
1998, and continuing through December 10, 1998. This
decrease in removal efficiency corresponded to an oper-
ational change at the plant. During this period, Plant B
was testing an alternative coagulant to alum called PAX-
18, which is a liquid polyaluminum chloride coagulant
that is supposed to reduce the amount of sludge pro-
duced. During the six sampling events that "occurred
while this alternative coagulant was used, total arsenic
concentrations averaged 18.8 ug/L at the inlet, 12.9 ug/L
at the prefiltration location, and 10.8 ug/L at the after-
filtration location. In cprnparison, results from total arse-
nic concentrations measured during the 43 sampling
events when alum was used as the coagulant averaged
19.1 ug/L at the inlet, 5.5 ug/L at the prefiltration loca-
tion, and 3.0 ug/L at the after-filtration location. These
results correspond to arsenic removal efficiency bf"43%"'
when the PAX-18 coagulant was being used and 84%
when the alum coagulant was used.
Removal efficiency using alum correlated very well to the
simple sorption model (McNeill and Edwards, 1997a). In
fact, the maximum deviation between the calculated and
actual removal was 12%, which is within the 90th per-
centile confidence interval of the model. Based on the
correlation, it is believed that arsenic removal is achieved
through adsorption on and coprecipitation with the alumi-
num floes. The iron concentrations in the source water,
34
-------
30
25
20
ง 15
c
o
o
o
10
100%
- 90%
- 80%
- 70%
- 20%
10%
o%
6/4/98 7/24/98 9/12/98 11/1/98 12/21/98 2/9/99 3/31/99 5/20/99 7/9/99
Date
Figure 4-8. Total Arsenic Analytical Results [During Long-Term Sampling at Plant B
which were figured into the sorption model, also may
contribute to arsenic removal because the paniculate
arsenic at the inlet is most likely attached to the iron.
Removal efficiency using the PAX-18 did not correlate
well to the sorption model. Actual arsenic removal was
28 to 42% less than removal predicted by the model.
Based on the arsenate results at the outlet, it appeared
that significantly less As(V) attached to the aluminum
floes produced by the PAX-18 than the alum. Research
indicates that arsenate removal efficiency decreases
above pH 7 using alum (Sorg and Logsdon, 1978; Sorg,
1993). During operation with PAX-18, the average pH of
the finished water increased from 7.4 to 7.8. This
increase may explain the difference in removal efficien-
cy. Additional research is needed to identify the mechan-
isms affecting removal of arsenic using polyaluminum
chloride. However, this study indicated that removal effi-
ciency using PAX-18 was significantly less than alum.
The Plant B water treatment system was able to con-
sistently remove arsenic to low levels when alum is used
as the coagulant (i.e., average treated water total arse-
nic concentration was 3.0 ug/L when alum was used as
the coagulant). The primary arsenic removal mechanism
was adsorption and coprecipitation with the alum coagu-
lant followed by sedimentation and filtration. Based on
the literature, increased arsenic removal could possibly
be achieved by lowering pH to 7 or below and by increas-
ing coagulant dosage.
4.3.4.2 Other Water Quality Parameters
Other water quality parameters also were analyzed to
provide information regarding the ability of the treatment
plant to remove arsenic. Table 4-12 summarizes the
analytical results for several water quality parameters
obtained during long-term sampling.
Alkalinity concentrations ranged from 119 to 146 mg/L
(as CaCO3) in the inlet with an average of 131 mg/L. Fig-
ure 4-10 shows that alkalinity in the source water fluc-
tuated slightly ^seasonally with the lowest concentrations
in the late summer and the highest concentrations in the
spring. Concentrations decreased between the inlet and
prefiltration sampling location and remained relatively
constant between the prefiltration and after-filtration loca-
tions. These data do not appear to correlate with arsenic
analytical results or removal efficiencies.
During long-term sampling, turbidity concentrations aver-
aged 3.4 NTU at the inlet, 0.8 NTU at the prefiltration
location, and <0.1 NTU at the after-filtration location. In-
let turbidity concentrations ranged from 11.8 to 1.0 NTU
and varied seasonally (see Figure 4-10). The highest tur-
bidities were observed in the late spring, corresponding
35
-------
Inlet
25
20 -
to
o 10
5 -
25
Prefiltration
^ ^ ^ ^ oS>* ^ J? & & & &
-------
Table 4-12. Summary of Water Quality Parameter Analytical Results at Plant B (June 1998-June 1999)
Parameter
Alkalinity
Turbidity
pH
TOG
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
mg/L
mg/L
mg/L
NTU
NTU
NTU
mg/L
mg/L
mg/L
pg/L
pg/t-
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
Number of
Samples
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
12
12
12
12
12
12
12
12
12
Minimum
Concentration
119
96
96
1
0.3
<0.1
7.9
7.2
7.2
2.8
2.3
1.7
43.4
67.6
28.1
32.2
<30
<30
11.0
0.6
<0.5
<11
41.7
25.7
<30
<30
<30
1.8
1.3
<0.5
Maximum
Concentration
146
132
126
11.8
1.2
0.3
8.6
: 8.1
8
9.8
8.6
8.7
501
809
98
507
75.6
57.4
39.0
18.2
5.8
'. <11
120
77
<30
<30
<30
7.5
9.7
<0.5
Average
Concentration
131
114
113
3.4
0.8
<0.1
8.4
7.5
7.4
3.7
3.1
3.1
173
493
56
164
<30
<30
19.6
9.3
0.7
<11
73
43
<30
<30
<30
4.0
5.5
<0.5
Standard
Deviation
7.8
10.2
9.4
2.3
0.2
0.04
0.1
0.2
0.2
1.0
0.9
0.9
129.7
145.3
18.2
129.3
14.1
6.4
7.1
3.7
0.8
NA
22.4
17.1
NA
NA
NA
1.9
2.7
NA
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
to snow melt and spring rains, while the lowest values
were observed in the winter. Coagulant dosages were
determined by the source water turbidity concentration
and ranged from 29.0 to 44.7 Ib/day (2.6 to 4,1 mg/L)
when alum was used and 14.0 to 16.7 Ib/day (1.3 to
1.5 mg/L) when PAX-18 was used. The data show that
Plant B effectively removed turbidity from the source
water; however, no correlation between turbidity removal
and arsenic removal was observed. Turbidity removal
was still very good (i.e., typically <0.1 NTU) when the
plant was using PAX-18, although PAX-18 was used
during the winter when turbidities were lowest.
The average pH was 8.4 at the inlet, 7.5 before filtration,
and 7.4 after filtration. As seen in Figure 4-10, inlet pH
was constant throughout the duration of the study. As
stated previously, the pH increase, noted at the before-
and after-filtration sampling locations, during usage of
the PAX-18 may have adversely affected the arsenic
removal efficiency. TOC concentrations were relatively
constant (see Figure 4-10), with averages of 3,7 mg/L,
3.1 mg/L, and 3.1 mg/L at the inlet, prefiltration, and
after-filtration sampling locations, respectively. A spike in
the TOC concentration was observed on May 20, 1999,
although the cause is not known. Eliminating this data
point would reduce the average TOC concentrations to
3.5, 3.0, and 3.0 mg/L at the IN, PF, and AF sampling
locations, respectively. The decrease in TOC between
the inlet and prefiltration sampling location is most likely
due to the coagulation process followed by sedimenta-
tion. The decrease corresponded to an average 14%
TOC removal.
Total aluminum concentrations averaged 173 ug/L at the
inlet, 493 ug/L before filtration, and 56 ug/L after filtration.
The average dissolved aluminum concentrations were
<11 ug/L at this inlet, 73 ug/L at the prefiltration location,
and 43 ug/L at the after-filtration location. The increase
in total and dissolved aluminum at the prefiltration sam-
pling location was due to the use of alum as the coag-
ulant. Based on plant data, alum dosages ranged from
29 to 44.7 Ib/day during the study, corresponding to alu-
minum concentrations ranging from 2,600 to 4,100 ug/L.
The PAX-18 dosages ranged from 14 to 16.7 mg/L,
corresponding to aluminum concentrations of 1,300 to
1,500 ug/L. These relatively high aluminum concentrations
37
-------
:.: I
14
80 ฃ
-Turbidity (NTU)
-pH (units)
-TOC (mg/L)
-Alkalinity (mg/L as CaCOS)
6/4/98
7/24/98
9/12/98
11/1/98
12/21/98
Date
2/9/99
3/31/99
7/9/99
Figure 4-10. Inlet Turbidity, pH, TOC, and Alkalinity Analytical Results at Plant B
were not observed at the prefiltration location because it
was located after trie sedimentation basin.
Total manganese concentrations averaged 19.6 ug/L,
9.3 ug/L, and 0.7 ug/L, at the inlet, prefiltration, and after-
filtration sampling locations, respectively. Average dis-
solved manganese concentrations were 4.0 ug/L at the
inlet, 5.5 ug/L at the prefiltration location, and <0.5 ug/L
at the after-filtration location. These relatively minor man-
ganese concentrations probably did not have a signifi-
cant impact on arsenic removal efficiency.
Total iron concentrations at the inlet sampling location
ranged from 32.2 ug/L to 507 ug/L and averaged 164 ug/L.
At the prefiltration sampling location, total iron concen-
trations ranged from <30 to 75.6 ug/L and averaged
<30 pg/L. The average total iron concentration at the
after-filtration sampling location was <30 ug/L. Also, aver-
age dissolved iron concentrations were below the detec-
tion limit at the inlet, prefHtration, and after-filtration sam-
pling locations. These data indicate that iron probably was
not a major factor in As(V) removal during treatment oper-
ations. However, arsenic may have been attached to the
Iron particles in the raw water, showing up as particulate
arsenic, which were subsequently removed.
4.3.4.3 Supernatant Discharge Water
The filter backwash water at Plant B is sent to a sludge
settling pond and the supernatant is discharged to the
adjacent river under a state permit. Supernatant dis-
charge water samples were collected from a manhole
located in the piping that transports the water from the
sludge settling lagoon to the river. Total arsenic con-
centrations ranged from 4.6 to 56.1 ug/L and averaged
14.0 ug/L, approximately half of which was soluble and
half particulate. Total aluminum concentrations ranged
from 359 to 7,500 ug/L and total iron concentrations
ranged from <30 to 191.5 ug/L. Results of supernatant
discharge sampling are summarized in Table 4-13.
4.3.4.4 Sludge
Sludge is generated at Plant B from sedimentation in
primary and secondary clarifiers and from backwashing
filters. For most of the year, wastewater and sludge from
the clarifiers is sent directly to a sludge lagoon. How-
ever, the wastewater and sludge are sent directly to the
sanitary sewer for 3 to 4 months in the winter due to
freezing conditions in the lagoon.
Backwashing occurs approximately every 50 hours. Back-
wash water is sent to a sludge settling tank. Sludge is
transferred from the settling tank and combined with the
wastewater and sludge from the clarifiers prior to dis-
charge into the sludge lagoon. Approximately once per
year, the sludge lagoon is dewatered using an underdrain
system and the dewatered sludge is sent to a landfill.
The volume of sludge sent to the landfill has not been
recorded, nor has metals analysis been performed.
38
-------
Table 4-13. Summary of Analytical Results from Supernatant Discharge Water Samples at Plant B
(November 12, 1998-June 17, 1999)
Parameter
As (total)
As (soluble)
As (particulate)
PH
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Number of
Units Sampling Events
M9/L
pg/L
ug/U
ug/L
Mg/L
Mg/L
pg/L
Mg/L
ug/L
8
8
8
8
8
8
8
8
8
8
Minimum
Concentration
4.6
2.5
0.2
7.5
359
<30
7.1
46.4
<30
<0.5
Maximum
Concentration
56.1
19.2
44.9
8.0 :
7,500
191.5
160.5
2,216.0
62.7
22.5
Average
Concentration
14.0
6.7
7.3
7.8
1,610
49.3
32.5
327.7
<30
4.0
Standard
Deviation
17.6
5.8
15.2
0.2
2,457
60.7
52.1
763.2
16.9
7.6
Sludge samples were collected on December 15, 1998
from three locations from within a dewatered sludge
lagoon. These sludge samples were analyzed for pH,
percent moisture, total arsenic, and total iron. Also, a
TCLP test was performed on each sample to determine
the quantity of leachable arsenic, barium, cadmium, chro-
mium, lead, mercury, selenium, and silver. Total arse-
nic concentrations ranged from 293 to 493 mg/kg dry,
and total iron concentrations ranged from 14,600 to
15,800 mg/kg dry. Arsenic was detected in leachate from
all three samples at concentrations as high as 0.160 mg/L;
however these concentrations were well below the regu-
latory limit of 5 mg/L. Table 4-14 presents the results of
sludge analysis at each of the three sampling locations.
4.4 Plant C
Water and residual samples were collected and analyzed
at Plant C, a lime softening plant, during three phases of
the study: initial source water sampling (February 1998),
preliminary sampling (April and May 1998) and long-term
evaluation (June 1998 to June 1999). Arsenic speciation
sampling was conducted during the initial source water
sampling, once during preliminary sampling, and every
fourth week during the long-term evaluation. The third
phase also included residual sample collection and analy-
sis. Supernatant discharge water samples were collected
monthly beginning in November 1998, and three sludge
samples were'collected during a single sampling event
from a dewatered sludge lagoon.
4.4.1 Plant C Description
Plant C serves a population of approximately 35,000
(more than 14,000 taps). The plant processes approxi-
mately 6.1 mgd and the design flowrate is 10 mgd. The
plant treats ground water using a lime softening process
followed by sand filtration. Figure 4-11 is a schematic
diagram of the,treatment process used at Plant C.
The treatment process at Plant C consists of the follow-
ing major elements:
Intake. Raw ground water from multiple wells (up
to 4) is combined in a common header.
Aeration. Aeration is used to oxidize iron.
Table 4-14. Analytical Results of Sludge Sampling at Plant B (December 15, 1998)
Parameter
Units
DL
Location 1
Location 2
Location 3
As-TCLP
Ba-TCLP
Cd-TCLP
Cr-TCLP
Pb-TCLP
Hg-TCLP
Se-TCLP
Ag-TCLP
TCLP extraction
pH
Percent moisture
As (total)
Fe (total)
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NA
%
mg/kg, dry
mg/kg, dry
0.05
1.0
0.020
0.030
0.20
0.0002
0.05
0.020
NA
0.1
61
379
0.058
1.3
<0.020
<0.030
<0.500
<0.0002
<0.050
<0.020
Complete
7.0
74.9
353
14,600
0.160
1.2
<0.020
<0.030
<0.500
<0.0002
<0.050
<0.020
; Complete
6.9
82.3
493
14,800
0.114
1.2
<0.020
<0.030
<0.500
<0.0002
<0.050
<0.020
Complete
6.9
78.2
293
15,800
39
-------
Clarification
Aeration (4 Units in Parallel)
Filtration
Raw Water
i :, from
Groundwater
"'. Wells
1 , h i
Supernatant Water-*.
Discharged to Creek
Under permit
Clarifier C'2Clb-
Sludge
Lagoon
Backwash Water
Sludge to Local Farm Fields
Figure 4-11. Schematic Diagram, Plant C
Clarification. Immediately after aeration, lime is
added to the water in the middle section of each
of four precipitators (solids-contact softeners) at a
rate of 245 mg/L (dry lime stored on site in silos).
In each of the precipitators, lime and water are
mixed using a paddle-wheel mixer. The retention
time In the precipitators is approximately 60 min-
utes. Sludge is collected from the bottom of the
precipitators, sent to a slurry tank, and then
placed in a sludge lagoon. Sludge from the lagoon
is used on local farm fields.
Chlorination. Chlorine is added into each clari-
fier collection trough at a rate of approximately
100 to 200 Ibs/day (correlating to approximately
15 mg/L).
Filtration. Filtering media consists of 10 inches
of graded gravel and 2 feet of sand. There are
15 separate filtering units that are backwashed
approximately every 80 hours. Backwashing
includes a surface scour.
iป Clearwell Storage. Treated water is chlorinated
prior to clean/veil storage. The final chlorine con-
ce^tration in finished water is approximately
6 mg/L (<0.5 mg/L free chlorine).
Backwash. Backwashing occurs every 80 hours
and the backwash water is combined with sludge
from the clarifiers, sent to a slurry tank, and then
on to a sludge lagoon. Sludge from the lagoon is
used on local farm fields. Approximately
200,000 gal/day of water goes to lagoons.
4.4.2 Initial Source Water Sampling
''if. , '" ! i, 'il!i.i,< i'l
!' <'!,!, '" 1|"1!1! '
The influent water is supplied from four deep (approx-
imately 300 ft) ground water wells. Typically, only three
wells are used due to problems with the fourth well re-
garding, among other things, high arsenic concentrations.
Based on plant records, the ground water hardness is
approximately 350 to 400 mg/L (as CaCO3) and iron con-
centrations are approximately 2 to 2.5 mg/L. Also, the
raw water contains 70 to 100 mg/L of CO2. Based on
samples collected and analyzed by the plant, arsenic
concentrations observed in the source water wells range
from <0.01 to 89 ug/L. Arsenic concentrations in samples
collected near Plant C on November 25, 1992, from each
of the ground water wells are presented in Table 4-15.
Table 4-15. Arsenic Concentrations in Ground Water
Wells at Plant C (1992)
Well
Number
6
7
8
9
Arsenic Concentration
(M9/L)
89
75
38
; <0.01
On February 27, 1998, an initial site visit to Plant C was
conducted and water samples were collected. The ground
water supplying Plant C is hard (averaging 336.5 mg/L as
CaCO3), with an average calcium hardness of 214.5 mg/L
as CaCO3 and an average magnesium hardness of
121.5 mg/L as CaCO3. Plant C also had relatively high
turbidity, averaging 20.5 NTU during the source water
sampling event. Consistent with plant records, the iron
concentration was relatively high, averaging 2,370 ug/L.
As would be expected for a ground water source, the
majority of the soluble arsenic existed as arsenite (83%
of the soluble arsenic). AsJV) was detected during the
source water sampling at an average concentration of
2.0 ug/L. Particulate arsenic was not detected in the
40
-------
source water samples. Table 4-16 presents the analytical
results from the source water sampling.
The average arsenic concentration detected during the
source water sampling event was 9.4 ug/L. This concen-
tration is lower than the minimum required for inclusion
into the preliminary and long-term phases of the study.
However, the historical data indicated that the source
water concentrations were much higher (see Table 4-15).
Therefore, the plant was included in the preliminary and
long-term sampling phases of this study. It was; deter-
mined during the preliminary sampling phase of the study
that the sampling tap used during the initial source water
sampling was not located properly (this issue is dis-
cussed in detail in Section 4.4.3).
4,4.3 Preliminary Sampling
Water samples were collected at three locations (i.e., IN,
PF, and AF) during the preliminary sampling phase of
this study. Sampling taps were available at the IN and
AF sampling locations; however, a scoop was used to
collect samples at the PF location. The inlet sampling
location represents a combined sample from the four
ground water wells and was located in the manifold piping
where the water from the wells is combined. The PF sam-
ples were taken from the channel surrounding precipitator
(i.e., solids-contact softener) No. 3 that transports the
softened water to the filtration vessels. Therefore, PF
sampling location represents water that has been aerated
and processed through the solids-contact softener. The
AF sampling tap was located after the filtration units
and represents water that enters the distribution system.
Figure 4-12 is a process flow diagram for Plant C that
shows each of the sampling locations.
Consistent with Plants A and B, preliminary sampling at
Plant C consisted of weekly sample collection and analy-
sis of various parameters (alkalinity, turbidity, pH, hard-
ness, total iron, total manganese, and total arsenic
analysis). Arsenic speciation sampling, which included
determination of soluble and particulate arsenic, was con-
ducted once during the preliminary study on samples col-
lected from each sampling location. Table 4-17 presents
the results of the 4-week preliminary sampling period.
Results from the preliminary sampling events indicated
that inlet total arsenic concentrations varied widely, rang-
ing from approximately 2.4 to 83.4 ug/L. The influent
samples collected on April 27 and May 11, 1998, con-
tained relatively low concentrations of arsenic (i.e., 3.5
and 2.4 mg/L, respectively), when compared to concen-
trations in prefiltration and postfiltration samples. Re-
analysis of samples confirmed the concentrations of the
influent samples. Similarly, the inlet concentrations ob-
served during the source water sampling event were rela-
tively low. Subsequent discussion with plant personnel
determined that the cause of the problem was the sam-
ple tap location. The sampling location was situated in
the manifold piping downstream of wells 6 and 9 and
upstream of wells 7 and 8. Review of the well operation
log indicated that well 6 (producing the highest As con-
centration among the four wells) was not in operation
during sampling on April 27 and May 11, 1999; however,
well 6 was running on May 4 and May 18. As a result of
this finding, a new sampling location downstream of all
Table 4-16. Source Water Sampling Analytical Results at Plant C (February 27,1998)
Parameter Units Primaiy Sample Duplicate Sample Average Concentration
Alkalinity
Sulfate
Turbidity
PH
Hardness
Ca Hardness
Mg Hardness
Total Al
Total Fe
Total Mn
NO3-NO2 (N)
TOG
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
mg/L<"
mg/L
NTU
mg/L<*
mg/Lw
mg/L""
Mg/L
Mg/L
Mg/L
mg/L5"
mg/L
Mg/L
Mg/L
pg/L
Mg/L
Mg/L
400
7
20
7.2
341
217
124
<400
2,410
200
<0.02
3
9.4
12.0
ND
10.2
1.8
397
7
21
7.2
332
212
119
<400
2,330
210
<0.02
3 I
9.4
12.0
ND
9.7
2.3
398.5
7
20.5
7.2
336.5
214.5
121.5
<400
2,370
205
<0.02
3
9.4
12.0
ND
9.9
2.0
(a) As CaCO3.
(b) Combined NO3-N and NO2-N.
41
-------
MONTHLY
As (total), As (III), As (V)
SLUDGE USED ON LOCAL
FARM FIELDS
As (total), Water Content,
pH, TCLP metals
INFLUENT
SETTLING
LAGOON
AERATION
PRECIPITATORS
(4 Units in Parallel)
SUPERNATANT WATER
DISCHARGED TO BAYU TECHE
As (dissolved and total), pH
As (total), As (III), As (V)
Backwash Water
FILTRATION
As (total), As (III), As (V)
NOTE:
Prefiltration water samples were
collected from Precipitator 3.
DISTRIBUTION
SYSTEM
WEEKLY
As (total), Alkalinity, pH,
Hardness, Turbidity,
Total Fe, Total Mn
Plant C
Lime Softening
Design Flow: 10 mgd
As (total), Alkalinity, pH,
Hardness, Turbidity,
Total Fe, Total Mn
As (total), Alkalinity, pH,
Hardness, Turbidity,
Total Fe, Total Mn
LEGEND
T .
Lime
Sampling Location
Sludge Sampling
Location
Disinfectant Addition
Point
Unit Process
Chemical Added to
Unit Process
Figure 4-12. Process Flow Diagram and Sampling Locations at Plant C
42
-------
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43
-------
wells (i.e., wells 6, 7, 8, and 9) was used for the long-term
sampling phase of the study. This new sample tap was
located just prior to aeration, the first treatment process
implemented at Plant C.
The inappropriate sampling location used during the pre-
liminary sampling events complicates evaluation of
arsenic removal efficiency. However, some observations
regarding the arsenic can be made. For example, the
soluble arsenic in the raw water entering the treatment
plant was approximately 94% As(lll). This level would be
expected for a ground water source. It appeared that the
majority of the As(lll) was oxidized to As(V) prior to
filtration using two chlorine treatment steps. The average
As(V) concentration observed at the sampling location
situated after softening and chlorine addition made up
approximately 97% of the soluble arsenic. The soluble
arsenic in the finished water consisted of approximately
95% As(V). Particulate arsenic was not detected in any
of the samples collected during the preliminary sampling.
Total arsenic concentrations in the finished water ranged
between 18.8 ug/L and 41.6 ug/L and averaged 27.4 ug/L.
Although arsenic removal efficiency could not be deter-
mined because of the raw water sampling location, the
data indicate that Plant C was not able to reduce arsenic
concentrations to low levels. Prior research indicates
that As(V) removal approaches 100% and As(lll) remov-
al approaches 75% at pH 11 (Sorg and Logsdon, 1978);
however, arsenic removal efficiency decreases rapidly
below pH 11. McNeill and Edwards (1997b) showed that
the primary arsenic removal mechanism during lime soft-
ening Is adsorption and coprecipitation of As(lll) and As(V)
with magnesium hydroxide, which is precipitated near
pH 11. Therefore, it appeared that pH limited arsenic
removal at Plant C, where the average pH after lime
softening was 8.9. This conclusion was further supported
by the limited removal of magnesium hardness. The aver-
age magnesium hardness concentrations decreased from
113 mg/L in the raw water to only 107 mg/L in finished
water.
Total hardness concentrations averaged 304 mg/L,
164 mg/L, and 153 mg/L (as CaCO3) in the IN, PF, and
AF sampling locations, respectively. The plant did soften
the raw water significantly; however, Plant C removed
primarily calcium hardness, which was reduced an aver-
age of 76% during preliminary sampling. As stated in the
previous paragraph, magnesium hardness was not ef-
fectively removed by Plant C, averaging only 5% re-
moval. Alkalinity decreased after softening and then
remained constant between the softening and after filtra-
tion. This decrease was expected due to the chemical
reactions that occur during the lime softening process
(for carbonate hardness only):
(4)
CO2 + Ca(OH)2 = CaCO3i + H2O (4)
Ca(HCO3)2 + Ca(OH)2 = 2CaCO3l + 2H2O (5)
Mg(HCO3)2 + Ca(OH)2 = CaCO3i + MgCO3 + 2H2O (6)
MgCO3 + Ca(OH)2 = Mg(OH)2i + CaCO3i (7)
Similarly, pH increased between the inlet and prefiltra-
tion sampling locations due to the addition of lime; how-
ever, this pH is significantly less than the optimal pH for
arsenic removal (i.e., pH 11).
Total manganese concentrations ranged from 130 to
230 ug/L in the inlet, <20 to 50 ug/L before filtration, and
<20 to 40 ug/L after filtration. The total iron concen-
trations averaged 2,851 ug/L at the inlet, 543 ug/L at the
prefiltration sampling location, and 41 ug/L at the after-
filtration sampling location. The iron in the raw water is
most likely in the reduced state since the soluble arsenic
was primarily As(lll) in the raw water. As observed in
Plant A, arsenic removal by iron oxides can be signifi-
cant. Therefore, the concentration of iron in the raw water
was important and research indicates that this iron can
positively impact arsenic removal efficiency (McNeill and
Edwards, 1997b).
Similar to Plants A and B, the preliminary sampling effort
at Plant C resulted in only minor changes to the long-
term sampling approach. Dissolved aluminum, iron, and
manganese concentrations would be determined every
fourth week using leftover samples from the arsenic spe-
ciation kits. In addition, aluminum was added to the list
of analytes and the inlet sampling location was changed
to be downstream of all ground water well inflows.
4.4.4 Long-Term Sampling
Weekly long-term sampling and analysis was performed
for 49 weeks to determine concentrations of alkalinity,
turbidity, pH, hardness, total aluminum, total iron, total
manganese, and total arsenic. Long-term sampling also
included 12 arsenic speciation sampling events that were
used to determinate arsenic form and species as well as
dissolved metals (iron, manganese, and aluminum) at
each sampling location. The same three sampling loca-
tions that were used during the preliminary sampling phase
also were used during long-term sampling. Additionally,
residual sampling was performed during this phase and
consisted of collection and analysis of supernatant dis-
charge water and sludge. Figure 4-12 shows the sam-
pling locations during the long-term evaluation phase.
4.4.4.1 Arsenic
Table 4-18 provides a summary of the arsenic analytical
results collected at the three treatment process locations.
Total arsenic concentrations at the inlet ranged from 15.9
44
-------
Table 4-18. Summary of Arsenic Analytical Results at Plant C (June 1998-June 1999)
Parameter
As (total)
As (total soluble)
As (particulate)
As(lll)
As(V)
Sample Location
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
ug/L
ug/L
ug/L
ug/L
ug/L
pg/L
M9/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Number of
Samples
49
49
49
12
12
12
12
12
12
12
12
12
12
12
12
Minimum
Concentration
15.9
7.7
6.3
21.9
17.3
13.9
<0.1
<0.1
<0.1
22
<0.1
<0.1
<0.1
12.6
13.7
Maximum
Concentration
84.9
: 32.6
, 33.1
\ 40.8
: 31.0
, 22.5
7.3
4.0
1.1
37.2
17.8
1.5
10.2
29.9
22.1
Average
Concentration
32.0
23.2
16.6
33.8
24.2
17.1
1.2
1.0
0.3
30.0
1.9
0.4
3.9
22.3
16.7
Standard
Deviation
10.5
5.6
4.2
6.0
4.6
2.4
2.2
1.5
0.4
4.9
5.0
0.4
2.9
4.9
2.4
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
to 84.9 ug/L with an average concentration of 32.0 ug/L.
Total arsenic concentrations at the prefiltration location
(i.e., after softening and before filtration) ranged from
7.7 to 32.6 ug/L with an average of 23.2 ug/L. Samples
collected after filtration contained total arsenic concen-
trations ranging from 6.3 to 33.1 yg/L with an average
concentration of 16.6 ug/L. The total arsenic analytical
results were relatively constant, with the exception of a
peak in the raw water arsenic concentration that occurred
on April 26, 1999. The cause of this peak is not known;
however, it is likely due to the ground water wells; operat-
ing during this sampling event (i.e., wells 6 and 7, which
have much higher arsenic concentration, may have been
contributing more to the influent flow). The average re-
moval percentage of total arsenic between the inlet and
prefiltration sampling locations was 28%. The average
removal percentage of total arsenic between 'the inlet
and after-filtration sampling locations was 48%. Total
arsenic removal efficiency also was relatively constant
during the long-term evaluation with the exception of
March 22,1999, when arsenic removal was a minus 53%.
The explanation for this data point is not known but may
be a result of well operation schedule, resulting in lower
than normal inlet arsenic concentrations. Figure 4-13 is a
graph showing the total arsenic concentration recorded
at each sampling location throughout the study, as well as
removal percentages calculated for each sampling event.
Particulate arsenic concentrations averaged 1.2 ug/L at
the inlet, 1.0 ug/L at the prefiltration sampling location,
and 0.3 ug/L at the after-filtration sampling location. This
indicates that approximately 75% of the particulate arse-
nic is removed by the system, primarily during filtration.
As(lll) concentrations averaged 30.0 ug/L at the inlet,
1.9 ug/L at the prefiltration location, and 0.4 ug/L at the
after-filtration location. Substantial conversion of As(lll)
to As(V) occurred between the inlet and finished water
due to the two chlorination steps. As(V) concentrations
were 3.9 ug/L at the inlet, 22.3 ug/L at the prefiltration
location, and 16.7 ug/L at the after-filtration location. The
data were relatively consistent regarding As(lll) and As(V)
concentrations at each sampling location. One deviation
occurred on August 3, 1998, where the As(lll) concen-
tration after the precipitators and before the filters was
17.8 ug/L and the As(V) concentration was 12.6 ug/L
The cause of this deviation is not known.
These data showed that the inlet water at Plant C con-
tained primarily the reduced species of arsenic (i.e.,
Asflll]) with only minor concentrations of As(V) and par-
ticulate arsenic. The As(lll) was converted to As(V) dur-
ing the aeration and chlorination step prior to clarification
(softening) arid the chlorination step prior to filtration.
The arsenic in the finished water consists almost entirely
of As(V). Figure 4-14 shows the fractions of the total
arsenic concentration made up of particulate arsenic,
As(lll), and As(V).
Based on studies by Sorg and Logsdon (1978), arsenic
removals should be low at Plant C due to the relatively
low pH (average pH is 8.8 after lime softening) achieved
during the softening process. Documented arsenic re-
moval efficiencies when only calcium carbonate is pre-
cipitated are between 0 and 10% (McNeill and Edwards,
1995). However, the average arsenic removal at Plant C
was 48%. This removal most likely is associated with the
iron in the source water. Total iron concentrations in the
source water averaged 2,303 ug/L, practically all of
which was in reduced state. It is believed that adsorption
and coprecipitation with the iron is the primary factor in
arsenic removal at this plant. Based on the simple sorp-
tion model by McNeill and Edwards (1997a), estimated
45
-------
90
80
70
60
50
40 J
30
20.
10
100%
80%
. 60%
a
40% >
E
o
o:
20% |
0%
S
01
0.
-20%
-40%
-60%
6/4/98 7/24/98 9/12/98 11/1/98 12/21/98 2/9/99 3/31/99 5/20/99 7/9/99
Date
Figure 4-13. Total Arsenic Analytical Results During Long-Term Sampling at Plant C
arsenic removals should average approximately 75%
(approximately 30% higher than observed). However, in
another study by McNeill and Edwards (1997b), it was
reported that carbonate can interfere with arsenic re-
moval by iron hydroxide due to competition for sorption
sites. Additionally, the available research provides little
information on arsenic removal by coprecipitation with
Iron hydroxide at pH values greater than 8.5. Therefore,
arsenic removal through adsorption and coprecipitation
with iron hydroxide appeared to be limited by the lime
softening process.
The Plant C water treatment system was not able to
consistently remove arsenic to low levels (i.e., average
total arsenic concentration in treated water was 16.6 ug/L).
The literature indicates that removal efficiency would
Increase if the pH was increased. The primary arsenic
removal mechanism is coprecipitation with the iron in the
source water followed by sedimentation and filtration.
4.4.4.2 Other Water Quality Parameters
As with Plants A and B, sampling and analysis of other
water quality parameters were performed to provide
insight into the arsenic removal efficiency at the plant.
Table 4-19 summarizes the analytical results for several
water quality parameters obtained during long-term sam-
pling.
Inlet alkalinity concentrations were relatively constant,
ranging from 300 to 411 mg/L (as CaCO3) with an aver-
age of 399 mg/L (see Figure 4-15). The alkalinity con-
centration decreased between the inlet and prefiltration
sampling location and remained relatively constant be-
tween the prefiltration and after-filtration locations. This
reduction in alkalinity was associated with hardness
removal during the softening process.
During long-term sampling, turbidity concentrations
averaged 26.3 NTU at the inlet, 9.8 NTU at the prefiltra-
tion location, and 1.3 NTU at the after-filtration location.
The inlet turbidity concentrations were relatively high,
ranging from 16.1 to 33 NTU, and are plotted on Fig-
ure 4-15. The data show that Plant B achieves an aver-
age turbidity removal efficiency of approximately 95%.
The average pH was 7.2 at the inlet, 8.8 at the prefiltra-
tion sampling location, and 8.6 at the after-filtration loca-
tion. Inlet pH was relatively constant (see Figure 4-15).
The pH increased at the prefiltration location due to the
46
-------
45.0
Inlet
40.0 .
35.0 -
^ 30.0 -
.3
| 25'ฐ "
| 20.0 .
1 15.0 -
O
10.0 .
5.0 -
0.0
DAs(V)
BAs (III)
gAs (particulate)
"x
Prefiltration
45.0
40.0 -
35.0 -
1 30.0 -
o 25.0 -
&
| 20.0 ,
= 15.0 -
o
O
10.0 -
5.0 -
0.0
J
-
I
I
I
, 1
I
"
if:
1
i
^** nป 0 1 **? N^1 (V^1 (0?* k^ f^^ r \^
After Filtration
45.0
40.0 .
35.0 .
75, 30.0 -
? 25.0 -
a
ฃ 20.0 -
0)
= 15.0 .
o
O
10.0 -
5.0 .
0.0 -
m
, I
r-i
,
-
nAs(V)
As (III)
gAs (particulate)
Figure 4-14. Arsenic Form and Species Analytical Results During Long-Term Sampling at Plant C
47
-------
Table 4-19. Summary of Water Quality Parameter Analytical Results at Plant C (June 1998-June 1999)
Parameter
Alkalinity
Turbidity
pH
Total Hardness
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Sample Location
Inlet
Prefiltration
After filtration
Inlet
Preflitration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Inlet
Prefiltration
After filtration
Units
mg/L
mg/L
mg/L
NTU
NTU
NTU
mg/L
mg/L
mg/L
Pg/L
P9/L
pg/L
P9/L
Pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
pg/L
Number of
Samples
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
49
12
12
12
12
12
12
12
12
12
Minimum
Concentration
300
125
146
16.1
0.7
<0.1
7.1
7.9
7.8
267
85
110
<11
13.4
<11
92
81
<30
75.9
3.6
1.0
<11
<11
<11
1512
<30
<30
106
<0.5
0.7
Maximum
Concentration
411
382
321
33
25.5
25
7.4
10.1
9.3
353
304
290
63
87
99
3768
766
1110
204
48.9
54.7
<11
36
12
2966
<30
<30
189
7.8
4.6
Average
Concentration
399
214
198
26.3
9.8
1.3
7.2
8.8
8.6
318
179
163
12
43
20
2389
397
76
140
12.6
4.8
<11
18
<11
2303
<30
<30
146
2.6
1.9
Standard
Deviation
15.4
40.9
30.4
4.2
5.9
3.61
0.1
0.5
0.3
17.6
37.3
29.1
13.3
16.1
15.9
556.7
181.8
165.2
27.5
8.2
8.0
NA
10.6
2.0
363
NA
NA
28.7
2.1
1.2
One-half of the detection limit was used for nondetect samples for calculations.
Primary and duplicate samples were averaged for calculations.
lime softening process. A similar trend was observed
with total hardness concentrations; however, the hard-
ness concentrations were relatively high at the inlet
(average 318 mg/L as CaCO3) and decreased after the
lime softening process to an average concentration of
179 mg/L at the prefiltration location and 163 at the after-
filtration location. It is important to note that the hardness
reduction consisted primarily of calcium hardness re-
duction; magnesium hardness was relatively constant
throughout the treatment process. This result is not sur-
prising considering that optimal magnesium hydroxide
formation is achieved at pH 11. Precipitation of magne-
sium hydroxide is associated strongly with arsenic re-
moval, because the arsenate adsorbs and coprecipitates
with the Mg(OH)2 (McNeill and Edwards, 1997b).
Total aluminum concentrations averaged 12 ug/L at the
inlet, 43 ug/L at the prefiltration location, and 20 ug/L at
the after-filtration location. The slight increase in alumi-
num at the prefiltration sampling location is probably due
to trace amounts of aluminum in the lime. Manufacturers
data indicated the lime contains 0.45% AI2O3. The aver-
age dissolved aluminum concentrations were <11 ug/L at
the inlet, 18 ug/L at the prefiltration location, and <11 ug/L
at the after-filtration location. Because of the low concen-
trations, aluminum is not considered a significant factor
in arsenic removal.
Total manganese concentrations averaged 140 ug/L,
12.6 ug/L, and 4.8 ug/L, at the inlet, prefiltration, and after-
filtration sampling locations, respectively. Average dis-
solved manganese concentrations were 146 ug/L at the
inlet, 2.6 ug/L at the prefiltration location, and 1.9 ug/L at
the after-filtration location. However, due to the relatively
low concentrations of manganese compared to iron, it is
not believed that the manganese is a significant factor in
arsenic removal at Plant C.
Total iron concentrations at the inlet sampling location
ranged from 92 to 3,768 ug/L and averaged 2,389 ug/L.
At the prefiltration sampling location, total iron concentra-
tions ranged from 81 to 766 ug/L and averaged 397 ug/L.
The average total iron concentration at the after-filtration
sampling location was 76 pg/L. Also, average dissolved
48
-------
46 .
41
36
I31
H
26
16
11
450
400
350
2-
300 .ฃ
-I- 250 ป
C
o
i
200 ?
-. 150
.-100
_Turbidity (NTU)
_pH (units)
AHardness (mg/L as CaCO3)
_xAlkalinity (mg/L as CaCOS)
6/4/98 7/24/98 9/12/98 11/1/98 12/21/98 2/9/99 3/31/99 5/20/99 7/9/99
Date
Figure 4-15. Inlet Turbidity, pH, Hardness, and Alkalinity Analytical Results at Plant C
iron concentrations were 2,303 ug/L at the inlet and
<30 ug/L at both the prefiltration and after-filtration loca-
tions. The data indicated that the iron in the source water
was in the reduced state and was completely oxidized
during the aeration and chlorination steps. The average
concentration of total iron at the inlet was reduced 97%
by the treatment process. It is believed that the primary
arsenic removal mechanism was adsorption and copre-
cipitation of As(V) with the iron.
4.4.4.3 Supernatant Discharge Water
The filter backwash water at Plant C is sent to a slurry
tank and then to a sludge settling lagoon. The super-
natant of the sludge lagoon is discharged to an adjacent
creek under a state permit. The plant is required to moni-
tor the supernatant discharge for pH weekly and total
dissolved solids (TDS) monthly as part of its discharge per-
mit. Supernatant discharge water samples were collected
at the outfall of the sludge lagoon where it discharges to
the creek.
Results of supernatant discharge water sampiing are
summarized in Table 4-20. Total arsenic concentrations
averaged 20.8 ug/L, consisting of an average of 21.2 ug/L
of soluble arsenic and 0.7 ug/L of particulate arsenic.
The pH was elevated due to the lime softening process.
As would be expected based on the concentrations in
the source water, total iron concentrations in the super-
natant water were relatively high and total aluminum and
manganese concentrations were relatively low.
4.4.4.4 Sludge
Sludge is generated from the lime softening precipitators
and from backwashing the sand filters. Sludge is col-
lected from the bottom of the four precipitators and sent
to a slurry tank. Filter backwashing occurs approximately
every 80 hours and the backwash water is combined
with sludge from the precipitators in a slurry tank and
then sent to a sludge lagoon. Approximately 230,000
gal/day of water goes to the lagoon. Approximately once
every 2 years, or as required, the lagoon is dewatered
using an underdrain system and the sludge is removed
(approximately 14,500 yd3 of sludge was removed in the
spring of 1998). Sludge from the lagoon is used on local
farm fields.
Sludge samples were collected on November 16, 1998
from three locations from within a dewatered sludge
lagoon at Plant C. These sludge samples were analyzed
for pH, percent moisture, total arsenic, total aluminum,
49
-------
Table 4-20. Summary of Analytical Results from Supernatant Discharge Water Samples at Plant C
(November 9, 1998^June 14, 1999)
Parameter
As (total)
As (soluble)
As (participate)
PH
Total Al
Total Fe
Total Mn
Dissolved Al
Dissolved Fe
Dissolved Mn
Units
M9/L
M9/L
M9/L
M9/L
(jg/L
M9/L
M9/L
M9/L
ug/t-
Number of
Sample
Events
8
8
8
8
8
8
8
8
8
8
Minimum
Concentration
14.7
14.9
<0.1
9.0
35
223
7.2
<11
<30
1.3
Maximum
Concentration
27.2
27.2
4.3
9.7
98
1,545
35.2
24.3
44.3
25.5
Average
Concentration
20.8
21.2
0.7
9.3
60
716
19.3
<11
<30
7.4
Standard
Deviation
4.3
4.0
1.5
0.3
24
505
10.1
7.2
10.9
7.9
total iron, total manganese, and TCLP metals (arsenic,
barium, cadmium, chromium, lead, mercury, selenium,
and silver). Total arsenic concentrations ranged from
17.0 to 35.3 mg/kg dry, and total iron concentrations
ranged from 3,190 to 7,920 mg/kg dry. Arsenic was not
detected in leachate from any of the three samples; how-
ever, minor concentrations of barium, cadmium, chro-
mium, lead, and silver were detected. Consistent with
Plants A and B, none of the sludge analytical results
from Plant C indicate exceedances of regulatory levels.
Table 4-21 presents the results of sludge analysis at
each of the three sampling locations.
Table 4-21. Analytical Results of Sludge Sampling at Plant C (November 16,1998)
Parameter
Unit
DL
Location 1
Location 2
(a) Detection limit is in units of ug/L for digestate.
Location 3
As-TCLP
Ba-TCLP
Cd-TCLP
Cr-TCLP
Pb-TCLP
Hg-TCLP
Se-TCLP
Ag-TCLP
TCLP extraction
pH
Percent moisture
Total As
Total Al
Total Fe
Total Mn
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NA
%
P9/9- dry
M9/9, dry
Pg/9, dry
pg/g- dry
0.05
1.0
0.020
0.030
0.20
0.0002
0.05
0.020
NA
0.1
0.1 <"
11'"
30("
0.5">
<0.05
3.3
0.03
0.06
0.25
<0.0002
<0.05
0.04
Complete
9.7
51.7
17.0
1,370
3,190
230
<0.05
2.6
0.03
0.06
0.27
<0.0002
<0.05
0.03
Complete
10.3
51.2
35.3
841
7,920
261
<0.05
3.9
0.03
0.05
0.25
<0.0002
<0.05
0.03
Complete
9.5
51.4
28.2
919
6,510
281
50
-------
5. Quality Assurance/Quality Control
5.1 Quality Assurance Objectives
The precision, accuracy, MDL, and completeness for
each of the analytical measurements required for this
study have been established in the QAPP (Battelle,
1998) and are listed in Table 1 of the QA/QC Summary
Report, which is being prepared under separate cover.
These terms serve as indicators of data quality and were
calculated in accordance with the formulas provided in
the QAPP. The precision, accuracy, and MDL of each of
the measurements performed during the present study
are presented in the summary report. These quality
assurance (QA) data are organized according to the
date of sample receipt or sample analysis and are not
site-specific. Therefore, the QA/QC section of this report
shares the same QA data with other water treatment
plants that have been included in the study.
5.2 Overall Assessment of Data Quality
Quantitative QA objectives listed in the QA/QC Summary
Report include precision as relative percent difference
(RPD), accuracy as percent recovery (%R), MDL, and com-
pleteness. The precision, accuracy, and MDL or reporting
limit of each of the measurements performed during the
present study are presented. Total arsenic, aluminum,
iron, and manganese analyses on water samples were
conducted in Battelle's ICP-MS laboratory. The QA data
associated with these metal analyses also are present-
ed. Other water quality parameters, including alkalinity,
pH, turbidity, hardness, nitrate-nitrite, sulfate, fluoride,
TDS, and TSS, were analyzed by Wilson Environmental
Laboratories and their QA data were summarized. QA
data for TOC analysis performed by CT&E Environmen-
tal Laboratory are presented. The TCLP metal analysis
on sludge samples also was conducted by Wilson Envi-
ronmental Laboratories and its associated QA data
are summarized. Overall, the QA objectives of precision,
accuracy, MDL, and completeness were achieved by all
laboratories. Therefore, all the valid data were used to
evaluate the effectiveness of the treatment processes
and support conclusions.
5.2.1 Total Arsenic, Aluminum, Iron,
and Manganese
At the early phase of the study, total arsenic analysis
was performed by Battelle's ICP-MS laboratory, and total
aluminum, iron, and manganese were analyzed by Wilson
Environmental Laboratories. Starting from June 1998, all
four metals were analyzed by Battelle ICP-MS labora-
tory. Therefore', QA data for only the total arsenic analy-
sis before June 16, 1998, and QA data for all four metals
afterwards are presented.
The laboratory duplicate and matrix spike (MS) analyses
were performed every 10 samples instead of 20 samples
as required by the QAPP. All the samples were analyzed
for four metals although metals other than arsenic may
not be required for every sample. Therefore, Battelle's
ICP-MS laboratory performed more QA/QC analyses
than what were specified in the QAPP. This fact should
be considered when QC data are evaluated.
Greater than 99% of the precision results for all metals
met the QA objective of ฑ25% (with only two iron out-
liers: 27% on August 8, 1998, and 74% on December
22, 1998; three arsenic outliers: 27% on August 18,
1998, 182% on October 1, 1998, and 27% on July 30,
1999; and four aluminum outliers: 26% and 33% on
August 18, 1998, 48% on December 15, 1998, and 48%
on January 25, 1999). The majority of the accuracy data
associated with MS analysis on August 31, 1998,
exceeded the QA limits of 75 to 125%. It is suspected
that MS analyses were not performed correctly on that
day. After this problem had been identified, Battelle's
WAL, laboratory QA officer, and Battelle's task leaders
met to discuss the cause of the deviation. Corrective
actions were taken including reanalyzing samples and
adjusting the amount of spike added to samples (i.e., the
iron spike was increased from 50 to 100, 200, 225, or
even as high as 2,000 ug/L due to the fact that most of
samples contain much more than 50 ug/L of iron). As
indicated in the QA/QC Summary Report, the MS data
quality was significantly improved since November 3,
51
-------
1998. Excluding the data on August 31, 1998, only five
As data were outside the acceptable range for accuracy.
However, 15 Al, 2& Fe, and 14 Mn accuracy data did not
meet the QA objective. With exceptions of one 23% and
one 38% of accuracy, the Al accuracy data range from
65 to 125%. The Mn accuracy data range from 67 to
106%, with exception of one 37%. The Fe accuracy data
range from 55 to 142%, with exceptions of one 14%, one
23%, and one 38%.
All laboratory control samples showed %R within the
acceptable QA limit of 75 to 125% except for six outliers
for total Fe with %R ranging from 73 to 143%. Al was not
spiked to laboratory control samples until November 3,
1998, after corrective actions were taken. The MDL of
Fe is the same as target MDL; however, MDLs of other
three metals were far below the target levels as specified
in the QAPP.
5.2.2 Water Quality Parameters
Water quality parameters include alkalinity, pH, turbidity,
hardness (Ca and Mg), nitrate-nitrite, sulfate, fluoride,
TDS, TSS and TOG. As shown in Table 3 of the QA/QC
Summary Report, all the precision data were within the
acceptable QA limit of ฑ25% except for two Mn analysis
with a 29% RPD (April 10 and 17, 1998) and three
nitrate-nitrite analyses with 40% RPD (August 6, 1998,
January 13, 1999, and February 11, 1999). The high
RPDs of these analyses might have been caused by the
low measured concentrations in the samples that were
close to the detection limits for Mn and nitrate-nitrite. The
accuracy data indicate that only one Al (70% on March
2, 1998), two Mn (66% and 64% on May 12, 1998), and
one Mg (126% on August 7, 1998) %R slightly exceeded
the QA objectives of 75 to 125%. Although the matrix
spike duplicate (MSD) analysis was not required by the
QAPP, the accuracy and the precision data relating to
MSD also were presented. The MS/MSD analyses are not
applicable to pH and turbidity measurements, though.
The laboratory did not perform MS/MSD analyses on Ca
and Mg hardness analyses till October 15, 1998 upon
Battelle's request. All laboratory control samples showed
%R within the acceptable QA limit of 75 to 125%. Re-
porting limits were below the required levels for all the
analytes except for sulfate. The reporting limit of sulfate
was 5 mg/L, exceeding the required MDL of 3.66 mg/L.
All precision, accuracy, and %R values for the TOG analy-
sis were within acceptable QA limits with the exception
of one accuracy value that was slightly below the 75 to
125% range at 72% (February 21, 1999).
5.2.3 TCLP Metals in Sludge
The TCLP metals analyzed in the sludge samples
included As, Se, Hg, Ba, Cd, Cr, Pb, and Ag. The preci-
sion data were within QA limits of ฑ25%. The accuracy
of MSs and percent recovery of laboratory control sam-
ples were all within QA limits of 75 to 125%, except for
one slightly elevated RPD for TCLP Se MS/MSD at 26%
(November 17, 1998).
52
-------
6. References
Amirtharajah, A., and C.R. O'Melia. 1990. "Coagulation
Processes: Destabilization, Mixing, and Flocculation."
In American Water Works Association (Eds.), Water
Quality and Treatment: A Handbook of Community
Water Supplies. New York: McGraw-Hill.
Andreae, M. 1977. "Determination of Arsenic Species in
Natural Waters." Anal. Chem., 49: 820-823.
Battelle. 1998. Quality Assurance Project Plan for Evalu-
ation of Treatment Technology for the Removal of
Arsenic from Drinking Water. Prepared for EPA..
Benefield, L.D., and J.S. Morgan. 1990. "Chemical Pre-
cipitation." Water Quality and Treatment.
Chen, S.L, S.R. Dzeng, M. Yang, K. Chiu, G. Shleh, and
C.M. Wai. 1994. "Arsenic Species in Groundwaters of
the Blackfoot Disease Area, Taiwan." Environmental
Science and Technology. 877-881.
Chen, R.C., S. Liang, H.C. Wang, and M.D. Beuhler.
1994. "Enhanced Coagulation for Arsenic Removal."
J. AWWA (September): 79-90.
Clifford, D., L. Ceber, and S. Chow. 1983. "Arse-
nic(lll)/Arsenic(V) Separation by Chloride-Form Ion-
Exchange Resins." Proceedings of the XI AWWA
WQTC.
Eaton, A.D., H.C. Wang, and J. Northington. 1997.
"Analytical Chemistry of Arsenic in Drinking Water."
AWWARF Project 914.
Edwards, M. 1994. "Chemistry of Arsenic Removal
during Coagulation and Fe-Mn Oxidation." J. AWWA
(September): 64-78.
Edwards, M., S. Patel, L. McNeill, H. Chen, M. Frey,
A.D. Eaton, R.C. Antweiler, and H.E. Taylor. 1998.
"Considerations in As Analysis and Speciation."
J. AWWA (March): 103-113.
EPA, see U.S. Environmental Protection Agency.
Ficklin, W.H. 1982. "Separation of Arsenic (III) and Arse-
nic (V) in Groundwaters by Ion Exchange." Talanta,
30(5): 371-373.
Gulledge, J.H., and J.T. O'Conner. 1973. "Removal of
Arsenic (V) from Water by Adorption on Aluminum and
Ferric Hydroxides. J. AWWA (August): 548-552.
Hemond, H.F: 1995. "Movement and Distribution of
Arsenic in the Aberjona Watershed." Environmental
Health Perspectives.
Hering, J.G., P.Y. Chen, J.A. Wilkie, M. Elimelech, and
S. Lung. 1996. "Arsenic Removal by Ferric Chloride."
J. AWWA. (April): 155-167.
McNeill, L.S., and M. Edwards. 1995. "Soluble Arsenic
Removal at Water Treatment Plants." J. AWWA.
(April): 105-113.
McNeill, L.S. and M. Edwards. 1997a. "Predicting As
Removal During Metal Hydroxide Precipitation."
J. AWWA. (January): 75-86.
McNeill, L.S. and M. Edwards. 1997b. "Arsenic Removal
During Predipitative Softening." Journal of Environ-
mental Engineering (May): 453-460.
Scott, K.N., J.F. Green, H.D. Do, and S.J. McLean.
1995. "Arsenic Removal by Coagulation." J. AWWA
(April): 114-126.
Sorg, T.J. 1993. "Removal of Arsenic From Drinking
Water by Conventional Treatment Methods." Proceed-
ings of the 1993 AWWA WQTC.
Sorg, T.J., and G.S. Logsdon. 1978. "Treatment Tech-
nology to Meet the Interim Primary Drinking Water
Regulations for Inorganics: Part 2." J. AWWA (July).
53
-------
Tate, C.H., and K.F. Arnold. 1990. "Health and Aesthetic
Aspects of Water Quality." In American Water Works
Association (Eds.), Water Quality and Treatment: A
Handbook of Community Water Supplies. New York:
McGraw-Hill.
U.S. Environmental Protection Agency. 1998. Research
Plan for Arsenic in Drinking Water. EPA/600/4-98/042.
Office of Research and Development, Washington, DC.
February.
54
-------
APPENDIX A
Complete Analytical Results from Long-Term Sampling at Plant A
55
-------
CO
U3
3
CO
$
E
o,
o
cu
CC
S
;:'
;::;,l"
!2
:::""- '
; :: -i
' "l"""
,,,,, ,,,,,,,
i '
^
ฃi
eg
S
CO
o>
tฃ>
^^
As (particulate
O O
V V
o o
* co
0 0
1
V)
CM CM
CM CM
0 O
co co
CO CO
4
1
in o
CO ฃ.
CO T
in oo
t m
o in
OO T-
m m
^
^"
o>
s
CO
in
co
>"
V
CM
en
o
EM
in
CM
^
in
m
in
T
_]
Total Al
CO CO
V V
CO 5
co co
CO 1^-
* CO
o
CO
V
s
"3-
^
co
CO
v
V
1
s
V
in
^
^~
\('
1
Total Fe
in in
ฐ ฐ
en i-
i- CM
* 05
CM O
CM CM
in
o
V
CO
en
CO
in
"v
^
"-
in
^
in
o
en
CO
CO
CM
CO
ฐ5>
Total Mn
^ ^
V V
y~ y~
V V
- T-
V V
1
1 Dissolved Al
ง g
V V
co co
V V
g g
V V
1
Dissolved Fe
in in
o o
V V
O 0
co co
en in
*- '-
4
Dissolved Mn
c
o
2
ซ=
CD
*;
co
ii
s
Q.
(a) As CaCO3.
IN = inlet; PF =
56
-------
oo
CD
O5
CM
D)
CM
CM
<
c
CL
d)
15.
at
ฃ
CD
05
I
O
CO
CD
CC
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o
CO
o
co
CO
5ป
Si
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CO
i
CO
i
s
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S-
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o
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o
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c
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lalysis.
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fl
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N = inlet; PF = prefi
59
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u.
<
u.
n.
z
<
CL
z
<
0.
z
u.
<
u_
Q.
z
ฃ?
Sampling Loc
Parameter
in
o
|
in
o
II
8ง
II
in
o
1
fe
s
T
s
T
CO
o
1
ฃ?
[c
<
$
p
CD
CM
t
CM
CM
O
*
en
o
I
ฃ?
T3
I
o>
1^
0
CO
CO
o> o
h- 00
o o
CO CO
v- CM
co co
1^
K
CO
0)
r-:
CT)
t^
CO
Q.
o
CO
CM
CO
CO
c\i
in cj
CM CM
CO O>
CM CM
* co
CM CM
CM
in
CO
CO
CM
in
CM
o
c\i
t
g
a
CO
CO
(0
1^
co
t
st- in
o o
V V
4
As (particulate)
in m
o o
* *
0 0
t^ (^
o o
4
3
co co
* *
h- CM
in in
CO CM
o o
ll
s
3
V
CO
&
o
CO
V
"tf-
O5
in
in
CM
CO CO
CO CD
V
*
fe
00
O5
(M
1
Total Al
f
CM
in
in
en
o
CM
ง
CO
O5
*
o
o
o o
co co
V V
oo in
co in
CO CO
05 h~
c\i in
0
"3
Tf
s
05
05
in
i
0)
U-
|2
n1:;
CM
CO
O5
*
in
ฃ
CO
in
o
o
CM
0
ci
CO
in CD
in in
CO CO
ctS
CO 0
CO O
>- co
co
CD
O5
in
C5
T-
1
c.
I
'v 'v
V V
V ^v
1
Dissolved Al
in '
i
o o
co co
V V
^y
o o
w
1
Dissolved Fe
co co
in in
CO CO
o to
CM 1-
4
Dissolved Mn
c
o
nated.
: = after filtra
E <
f g
|1
m -
a) AsCaCO3.
b) Sample contains
N = inlet; PF = prefi
66
..: : :: 1 .:.. :.::.
-------
O5
C3)
co
CM
JO
Q.
cป
c
"o.
as
CO
O)
3
8
(Q
o
J2
(0
Y'- <
A'-;
'<$'
;;ง
1
Y
y/
'
"'/f'
'ง>
1
..'
*;
-
1?
fil
,-,
Q
1"
CO
/'U.
it''
*-/
*""
^JVH
ซ
* * "~"
--
".'?^
D_
\ vv
1'
'"'UL
a.
z
|
ป,:, . Sampling LOG
Parameter
O
T
ฃ
CM
88
O) O)
O 0
ฃS
o>
o
o
CM
8
8
1
1
ฐc
1
CD
U3
CO
-
ฐฐ
r-M-
CM CM
CM CM
O
V
CO
CM
i
t--.
cq
H
'5
'&
O
CO
0
CO
CM
CO
o o
CO CO
o o
CO CO
CM CM
CO CO
CO
CO
CM
CO
CO
o
CO
CM
CO
in
0
CM
CO
CO CO
CM CM
O CO
co co
co in
CM CM
CO
co
c\i
CO
CM
en
CM
t
o
R
5
ed
3
i-O
*
CT
r-
r
CCI CO
,,
T" O
m co
T T
CD in
CTl CO
m
CM
to
CO
CO
A
II
As (total)
co in
CM CM
m in
0 i-
cn CD
1
1 As (total soluble)
o o
V V
en co
m *
O 0
'S)
a.
As (particulate)
o o
to m
o o
co co
O 0
1
CO
CD in
CO CO
co i~-
>t in
CO CO
1
CO
"v
5?
C\l
cq
CO
r^
^
m
CO
in
CO
r T-
V V
CO CM
CM CM
as
CO
ง
8
1
i
o
3
CM"
g
o
CO
V
m
1
CM
K
W
co_co_
CM CM
CM
CO
CM
ง
8
1
o
LL
5
CM
CM
0)
CO
CO
CM
CO
s
CO CO
in in
o o
CNJ CO
CO CO
1^ T-
CM CM
CO
in
in
cq
ll
c
5
\-
T- r-
V V
V V
y -^
'a
Dissolved Al
o o
o o
co co
V V
o o
CO CO
V V
ll
Dissolved Fe
CO CO
o en
CO CM
CM *-
4
Dissolved Mn
8"
o
g
13
= after
S
iฑ
"S
Q.
67
-------
1 '!>
CO
CD
~3
2
I
JL
'" en
8
T-
8
O
Y
S
8
S
T
1
^
^
t
o o
V V
CD If)
0) 0)
$
t--
c\i
i
CD
V
CO
CO
CO
0
3
ฃ
?
t:
CO O)
r- h~
01 0>
l^ t^-
CM CVl
CO CO
!-:
CO
CM
CO
q
CO
o
CO
CO
CO
Q.
CJ -r-
CM CM
* U3
CM CM
o in
CM CO
CM
c\i
co
CM
o
CM
in
CM'
*
CM
1
.
CO
co
(0
CO
in
CO
CO
CM
co
o
ป*
1^
in in
CO CO
in en
O CO
* o
T- 0
T T
CM
*
I~-
(0
o
cri
i
t
^
,
co in
CO CO
CO CM
* *
* in
en en
i
total soluble)
3.
o o
V
CM h-
in M-
O CD
CM O
1J>
particulate)
CO
<
* *
O 0
^ CO
o o
co en
o o
ll
^
co co
o en
t co
CO CO
CO CO
i
>
3
CO
CO
1
CO
K
V
o
o
o
e
t-- in
05 1-
t- en
* CO
in -
CO
O3
CO
3
1
<
1
o
V
!
o
5i
?
o
l-~
CO
|
W
งCM
in
in
* r-
in in
CM CM
o
^
CM
CO
*
s
1
ฃ
5
CM
in
N-
c\i
in
CO
CO
en
CO
r--
8
h~
Si
CO rf
CO CO
r~ co
88
CO O
in co
co in
h-
co
in
in
o
0
1
C
e
T 1
V V
~v V
CO
^v
1
solved A!
-------
APPENDIX B
Complete Analytical Results from Long-Term Sampling at Plant B
69
-------
(O
in
ca
q>
m
*-*
co
s:
1
ฃ
O)
tn
1
rr
is
.2
m
CO
*cr
: ,
::"'
CO
j ..<>:
i'
oo
CO
i
Q-
Z
LL
U.
Q-
z
LU
U.
D.
Z
U-
u.
Q.
z
1
1 Sampling Loc
Parameter
CO
03
CO
03
S
V-
T
O
8
in
CM
S
ฐ
CO
CM
1
OO
o
T
o)
"co
i1 i "
v
CO
o
^
oo
i
oo
d
CM
i
CO
d
in
co
d
en
d
CO
^
1
|
i .
CO
CO
co
CO
CO
CO
CM
CO
CM
CO
CO
CO
CO
1-^
1^
CO
Q.
CM
co
CM
co
en
CO
5
CO
co'
en
CO
CO
CM
CO
CM
CM
CO
co
CM
CD
CM'
CM
co
t
o
ฃ
t^ CD
CM CM
CD *
l-~ I--
00 h~
o
CM
CO
co
0
in
CO
o
co
CO
CO
^
co
CO
CO
10
T-
i
i
en en
CM CM
CO CO
CM CM
* CO
en en
4
As (total soluble)
vv
O CO
CM T-
V- V
o o
V V
i
As (particulate)
co o
O T-
d
CM i-
i
5.
Iv
co en
CM T-
0 f~
CM T-
CM CM
CO CO
4
1
f~ CO
co in
CO CO
co en
CM CM
in tn
co co
CO CO
ง
in
S
in
i
1
i
5-
CO
8
1
4
i
"i ' !J!
q
O O
CO CO
V V
o o
co co
V V
5$
s
o
co
V
in
S
1
ซ
CO
o
9
ซ
m
4
Total Fe
'| V:
co in
o o
V
en en
00 00
t i-
i- CM
co co
in
CO
in
CM
in
en
CO
CO
co
in
d
CO
CO
CO
CO
co
4
Total Mn
1 -i
^f CD
OO CO
CO CO
h- CO
(^ CO
in in
in CM
4
Dissolved Al
o o
CO CO
V V
o o
co co
V V
o o
CO CO
V V
4
Dissolved Fe
in in
o o
V V
CO CO
in in
Is- CO
CM CM
4
Dissolved Mn
.'.i..
d
= after filtrati
'1
Q.
II
Ou_
oo.
3 if
w c
^ II
70
-------
03
C35
OS
CO
O)
CO
CM
00
a.
"5.
C3
CO
O)
jj
2
CO
ฃ1
CO
ฃ
-
r-g,
rง;
v^
l'
/*'
O>
f
"* l!~
&s
1
*"',/
,-"
CO,
1
-
1
a
g:
"a.
,
\
' a.
*
'
-',
a.
~
*
*
U.
n, .
ซ''
*
r
"^V
z
/ *ฑ
c.
f!
o o
So?
O CD
o en
t- O
CM CM
8
o
en
en
S3
o
ฃ
o
s
8
88
SS
sl
L
B
&
ฐฐ
10 co
co co
?
CM
co
co
i
00
C3
O
CO
T- 1
ฐฐ
o o
00 i-
co t^
ฃ
'o
1
CO CO
CO CO
10 to
CO 00
to
00
CO
s
CO
00
^
l^ h~
ป*
00 00
a.
00 h-
CM CM
00 CD
CM CM
to co
CO CO
f-
i
O
CO
CO
co
0
CO
en
CM
IO
CO
en o
CM CO
en oo
CM CM
CO CO
CO CO
_i
E
O
CM
CM
to
CO
*-
T- |-~
<) CO
N CM
to 10
CD T-
^- co
CO
00
00
to
CO
CO
o
co
CM
00
^
I
CO 1^
CO CO
oo oo
CM CM
O CD
00 00
T T-
1
As (total soluble)
co i-
v
en *
CM CM
vv
1
As (particulate)
CM CM
o o
CO CM
o o
**
O 0
1
=
co to
CO CO
CO IO
CM CM
CO CM
X CO
1
I
CO
T
CO
IO
ง
CM
0> i-
CO f-
co co
CM en
งT-
IO
^f en
i- O
CM
CO
CM
5
to
"
CO
O)
to
o
to
s
i
o
CO
V
'5
CM
o o
CO CO
V V
o o
CO CO
CM CM
*
;ซ
1
"
CM
co
co
CO
: en
. _i
1
00
o
N
IO
^
00
h- oo
o o
IO CO
* CM
* *
t CO
en
c>
co
co'
CO
CM
to
V
CM
CO
o
en
CO
1
c
CM 0
O5 O
"3- IO
CM T-
O> O
CO N-
V V
1
Dissolved Al
0 O
co co
V V
0 O
o o
VV
s
CD
U-
1
a
IO IO
O 0
V V
oo oo
00 00
r- co
CM CM
1
Dissolved Mn
S
71
-------
o
t^
CD
1
O
*-*
8
CO
P>
"5.
I
ฃ
GO
M
s>
CO
<
s
Q>
?
CO
0>
a
s
III
1
II1 II 1
CO
o>
, ฃ:,
-1
I
1
Q
ft
Q_
z
<
a.
z
u.
<
U-
Q-
z
ft
LL.
a.
z
|
w g
o
Sen
05
Y
0
Sen
en
T-
cn en
CM
o
0
CO
en
8
T-
1
1
ง
s
*
0
T
s
1
.2-
]c
"3
26
<
?o
V
to tn
o o
tf CO
* *
o
V
0
co
*
^
h-
o'
*
^
?'
en
C3
co
CO
3
S-
TO
e
H
CO CO
1^- C-
co co
r- r-
CO CO
co oo
CO
i~-
co
t~.
*
00
CO
l^
co
i^
>t
CO
in
l^
CO
t^
CO
CO
a.
in CM
CO CO
o en
CO CM
1- O
* *
CO
Oil
CO
f~
CO
o
CO
CM
co
I--
CO
en
CM
co'
r-
eo
1
g
CO
M-
co
CO
i- in
CO CO
in co
in ^i-
O CO
CO CO
c-
CO
en
in
en
r-.
CM
co
in
CO
in
T
1
I
co co
CO CO
CO f-
CM CM
co in
en en
1
1 As (total soluble)
T" T-
d d
V V
i^. en
CM -^
o o
V V
1
As (particulate)
T ,
??
?]
CO
<
CO
s
ง
CO
in
S
CO i-
Sa>
CO
CO O
CO ป
in in
co in
r- r-
C3
K
S
TT
oo
fr
oo
0
CM
CO
(0
ES
g
1
1 Total Al
s
?
CO
s
งs
V V
o o
co co
V V
CM *
Sfc
o
^
o
CO
V
CM
s
ซ
*
ง
s
CM
i
[Total Fe
in
?
*
I--
1^
*
in in
0 0
h- en
CM O
r- CO
co in
CO
d
eo
d
in
in
I^
d
o
*
00
1
c
H
en CM
SS
r^ -r-
CO 1^
t^ t-~
V V
i
Dissolved Al
o o
co co
V V
o o
CO CO
V V
o o
<3 V
1
Dissolved Fe
in in
o o
V V
oo h~
O) O5
oo r~-
* *
^
Dissolved Mn
5
= after filtrati
ft
cf
o
1
g
D.
II
Ou.
O Q-
co .-
O a!
<2 <=
< II
Ifz
72
-------
OO
O)
oo
J__
1
S
i_
CD
"E
0)
S.
CD
m
cป
c
"5.
co
CO
.2
D)
CO
o
CC
1
is,
CO
CO
-
/
8
f-<'
u.
Q.
-S"
*
'/li,
CL
z
' /~
g
I l
CD
.S >_
1
88
ฐฐ
ii
0
in
o
o
CM
o
CD
o>
o
ivl
O)
S!
T
8
o
CO
O)
05
1
.f
t
T T
V V
CO 00
T- CO
C\J CM
CM
i
1^
C>
*
*
3
t
ซ
H
* *
r- i--
* Tf
h- 1^.
* *
00 00
CO
h~
*
(^
CO
CO
co
i--:
co
(^
CO
00
CO
i^
co
h-^
CO
CO
o.
CM CM
co co
co co
* CO
00 0>
CO CO
CM
CO
CO
CO
en
co
co
0
CO
O)
co
t^
CO
CO
CO
en
CO
t
O
g
*
CO
in
l^.
CM
CO
CO ^'
CO Kl
CO CT.I
(-ป [v.
co o
CO 0-.I
o>
CO
0
in
in
CO
0
^
CO
in
CM
CO
"&
I
*
co co
CO CO
* co
co co
CM *
en en
1
As (total soluble)
o o
V V
* CO
* *
o o
V
i
As (particulate)
in 10
O O
in in
0 0
CO CO
O O
1
3
00 00
CM CM
en oo
CM CM
CO CO
CO CO
1
g
3
CO
s
8
CO
5
T-
o co
co i-~
in in
S fc
is
1^ CO
^f 00
00 CO
h-:
ฃ
1
0
fc
o
s
CO
ง
f~
s
4
1 Total Al
":
^
|
CM i
O O
co co
V VI
80
co
V V;
f- *]
in co
N l^1
j
<
00
S ;
o
CO
V
o ,
9 ,
CO
fc
4:
.
T ^~
OO OO
co co
i^
0
t^
o
o
*
T
in
CD
CD
d
o
i^
1
c
2
ฃ
CO CM
CO CD
^- CO
co co
SCO
CO
"v *v
i
Dissolved Al
9*9
o o
CO CO
V V
co co
V V
1
Dissolved Fe
in in
?
-------
CO
I
I
Q
i
cn
cu
DC
15
9
m
o>
a
a
CO
s.
1?
1
1
"
10/15/98 ,
S
1 Sampling D
Q.
z
u.
Q.
Z
*
u.
D-
z
il-
ia.
D.
Z
a;
o
1
[Sampling Loc
Parameter
CD O5
T- Y
O5 CO
* co
CM CM
CO
CO
Y
a
1
1
a
CO
o
o
i
1
.ฃ>
c
1
T T
vv
CO CO
o o
CM CM
?
CO
0
i
CO
o
T-
5
f.
o
oo
CM
ID
'u
&
3
O 0
00 CO
CM O
CO CO
CM CM
CO CO
N
00
^
00
TO
5
TO
CO
2
5
TO
CO
Q.
T- CM
TO TO
O O
TO TO
* in
TO TO
^
TO
TO
TO
TO
TO
0
TO
TO
00
CO
CO
CO
t
g
00
'-
in
in
CO
o
CM
00 CM
cn o
TO *
CM CM
T- T-
CO Iป-
cn cn
T- Y-
CO
cJ
0
in
05
cn
TO
in
CO
CO
1
I
cn
0 0
in in
05 05
* CM
cn cn
1
As (total soluble)
ฐฐ
co cn
CM CM
* in
o o
1
As (particulate)
TO TO
O O
TO TO
0 0
* *
O O
ll
5.
00 CO
O5 O5
CM CM
cn cn
o co
O5 CO
1
>
^
CO
CD
g
ง
CO
-------
CO
cn
CO
CD
"I
CD
O
CD
Q
o
OJ
0)
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I
m
cn
.
I
E
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D)
I
E
CO
CD
DC
1
ca
CO
co
''
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CO--
f
y.t
A
^00
/'^
"1
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2
in
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;
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r>
CO j
$3^
v-
~i
a
CO
c
I"'
tn
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,,
,.
0- ,
"-",
2
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d
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1
c
CM CM
co in
CM CM
tf ^_
S3
V ^
4
Dissolved Al
w
^
w
4
Dissolved Fe
in in
ฐฐ
in T-
* in
in *
4
Dissolved Mn
c
= after filtrati
cf
o
1
IB
a.
II
Ou.
OQ.
3f
I 'ill'''
i: iiiii f
82
-------
APPENDIX C
Complete Analytical Results from Long-Term Sampling at Plant C
83
-------
CO
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cn
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cn
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cn
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o
ง
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t
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CMO
co co
CO CO
t-- cn
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CO
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cn
c\i
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CO
CO
CO
co
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^
CO
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cn o
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CO <*
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CO
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r-
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V
o
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CO
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a
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in in
o o
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g
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i
s
s
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CO
fe
co
51
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II
1
f
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co co
in
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CO
0
en
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o
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CO
co co
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in ^~
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en
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cn
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CO
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in
CO
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cn cn
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o co
CO
CO
cn
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s
%
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in
co
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L
E
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CM r-~
^ in
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CM l-~
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8
CM
in
0?
CO
in
^
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CO
l-~
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f- O
co co
f~ cn
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CO CO
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1
Ca Hardness
CM T
T- T-
CM in
\i ^
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LO
LO
CM
i
^
ง
13
.*
Rfc
co <
T" T-
a> co
1
II
I! Mg Hardness
cn
^
CO
CM
f-
c3
en co
o o
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o t^
en co
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co co
CO f-
co co
CO
8
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S
CO
CO
CO
CO
en
in
S
fe
1
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<* r-
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CO t--
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As (total solubl
ฐ "v
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en co
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1
1
o co
CM CO
CM CO
^f cn
CM CM
in h-
o in
1
f
CO
1
CO
ง
JI
CO 0
CM :co
CM T-
o cn
CO 'CO
* CO
T-'CO
^
in
CO
o
CO
!JZ
en
CM
rf
CO
CO
CO
*
S
ฃ
o
V
eS
f2
co
CO CO
S co
M f-
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co en
cn o
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"
cn
CM
o
CO
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i
co
CO
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o
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CO
*
CO
o
1
c
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r- co
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^r*
of
CO
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in cv
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cn in
8 co
1
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T- O)
O O
V
O T-
i- O
V
o o
4
_
As (particulatt
o o
o o
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i- N
CJCJ
i
CO
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m c\
co in
CM CV
00 00
cn o
4
CO
CO
CO
CO
^
cn co
in 05
CO CM
o in
3 3
in h~
in cv
0
CO
CM
in
IS
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oo
co
S
j;
4
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o
co
V
cn
CD
CM
cn
oo
co in
in in
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5 ?
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05 o
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in
co
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S
*
in
Y-
a>
o
S
8
CM
4
ฃ
in
in
CO
o
CO !-
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T- 0
co in
I^ CO
T- T-
co
CM
m
'-
CM
OO
00
in
cn
CM
1
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V V
r^ r^
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CM CM
T- T-
V V
4
i
S
o o
co co
V V
o o
co co
V V
^ cn
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CM CM
1
Dissolved Fe
o cn
CM T-
o o
in in
LJ LU
1 t
4
c
1
o
CO
CO
b
ง
ฃ
<2
15
LL
cf
g
S!
Q.
(a) AsCaCO3.
IN = inlet; PF =
86
-------
CD
O)
O)
m
L_
0)
JD
^
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co
o
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1^j;Samp|ng_lBca
='Parameter'fv-i:
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CM
CO
CM
t^
CO
O5
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CM
CM
i
CM
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1
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Y 1
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0
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CO
o
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CD
CM
o
CO
CM
CM
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^
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CO
o
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co
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0
co
CM
CO
CO
co
CO
N
Q.
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T- T-
H
CO 1^
n co
%
CO
CO
CM
R
CM
co
s
T-
o
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1"
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Is
SJ
ss
T T
CO
CO
fฐ
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1
CO
0
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T
co
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o
h-
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T \
T T-
Sง
CMS!
T V
LO
O
'"
CM
cn
C3
<
i
i
ฃ
CM
CM
CD
4
As (total)
CO 05
CO CO
CO 00
ss
o N.
ฃQ LO
i
As (total soluble)
CM O
O O
CJ CM
O f-
4
As (particulate)
o o
f*~ ^
o o
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s ro
4
i!
CO CM
LO CO
CO CD
O 0
CM CM
i
I
N;
Q3
CO
CM
V
O5 O
"."
05,05
5 5
T- T-
V, V
cq
CO
S
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w
CM
o
s
'v
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CO
LO
8
5
CM *
z%
CO CM
CO CO
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CO
CO
o
CM
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S
CO
1
1
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CO
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CD
1
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v- CD
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1
S
f--
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CO
C3
05
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1
C
1
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T- T-
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^ ^
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T- 1-
V V
1
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o o
o o
V V
CO O
o r~-
CM"T-"
o>
n.
Dissolved Fe
CO CO
T f
O5 O5
0 O
CO t>-
4
Dissolved Mn
ง
1
Q.
> II
87
-------
1 1
!!!'', I 1 1
":':
1 V: . ! ' 1
? , I
i.'i
r" i '
;' { '
": i
i"; 1 !
'M ,
'M'iii i , -I
ii [ ;
: ! '
in
I
-' : , (D
,r |
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. ; ;::ฃ
6
,!!!!'!',"!"! *-*'
d>
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6>
ii 3
.'n ' i C
: '" : 1 i ง
ซ*
* i ' \ \ *ฃ
'i '"' 1 OT
. M CO
?s
CO
Y-
N;
SI
T-
co
o
0
a
8
T-
ง
1
Mg Hardness
CO
T
co
co
CM
CO
T-
co
co co
CM CM
T- >*
CM *-
CM CM
o to
as
co
CM
CM
p
CO
CO
CO
CM
1
1
I
CM O
in in
CO 0
>t CO
CM CM
^
coco
1
As (total soluble)
?
^
co'
CO
V
1- CM
in *
CM T-
0 CO
T- T
V V
0
*'
in
CO
CM
0
CO
co
CM
^
^
i
,
o
CO
V
o>
in
in
CM"
in o
CD O
cn <$
in T-
co co
00 I^.
CO CO
CM" CM
ซ
in
cn
CM
CO
CO
co"
CO
85
in
in
s
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1
CO
LL
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nun
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p
T
O5 h-
in in
in ^i-
co co
LO IS
cn
in
CO
s
CM
h-
CM
CO
!
4
Total Mn
' '!
T
T-
V
c
s
T
1~
V
1
T
CO
"v
4
1
5
:::
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o o
co m
v v
o o
co in
co ^
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4
1
5
"v: '' '"""''
t^ co
CO CO
T T-
22
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c
1
5
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C
o
13
=5
1
II
c"
o
1
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Q.
ป S3 n
O 'S LL.
O ฐ 0.
5-gz
88
-------
oo
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c
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8
//
T_
00
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s
*
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&?
CM
ro
^~
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|c
15
CO
o
CO
CM
in
CM
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^
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CM
CD
CO
T-
Si
O
V
in
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CM
i
5
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en
CO
CO
CO
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rx-
%;/
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CO
o
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i^
00
o
CO
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Q.
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CD
8
-
^.-
o
in
in
CO
CO
TO
S
CO
CM
CM
CO
CO
1
Total Hardness
|s_
oo
CO
en
ง!
o
_*
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^
CO
to
CO
CM
CM
^
in
CO
a>
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CM
E
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03
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CO
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^
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03
o;
03
CD r~
in in
* o
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* in
co co
i-
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CM
CO
CM
CO
en
co
0
CO
CM
in
t
I
CO
en co
ฃ ฃ
CO 01
in in
CM CM
88
7
1
As (total soluble
o o
V V
"v *v
??
~,
s, '
4
As (particulate)
CM CM
O O
CO CM
o o
r co
38
v/~
> s
i
ฅ
f- <*
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CO [-
in in
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O CO
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*
4
|
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CO CO
CO
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CO
fs^
co
^
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V
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1
in co
co in
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00
in
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Q
V
en
g
[*^
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co
8
en
in
o
CM
4
Total Fe
CO CD
co en
^ *
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in *
-
o
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0
in
CD
T
^
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CM
*
i
Total Mn
V V
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V V
V V
1
Dissolved Al
O O
CO CO
V V
m 8
V V
in co
CM CM
4
Dissolved Fe
en oo
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en en
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h- f~
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\
c.
1
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CO"
o.2
X oj
0,1
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o),-*-*
o> c
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ol
(a) AsCaCO3.
(b) No sampling
IN = inlet; PF = p
89
-------
;, :?!';" /'
> 'in.;
, : 'H; '
TI '. CM
i
&
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C
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t
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1
2
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s
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1
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LL
0.
z
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LL
Q-
2
LL
LL
Q-
2
LL
LL
D.
2
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[Sampling Loca
Parameter
CO
CO
T-
0
^*
SS
OJ CM
ฃ2 5"
Is* N-
T T-
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CO CO
1
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s
co
CO
CO *
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1
H
CO
CO
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t-.
CO CO
CO CO
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CO CM
f- r--
Q.
te
^
m
CO
CO l"~
CO CO
ee
O M'
1
Total Hardness
^
5
CM
P:
CM
CM
CD CD
CO CO
in in
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o in
o o
1
Ca Hardness
CO
CO
8
CM
Y-*
II
in i-
cd cd
CO CO
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CM i-
1 T-
05
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0
CO
in
CO
^j-
8
CO
^
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CM
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8
1
I
CO
i
As (total soluble)
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ll
=
i
CO
T~
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V
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^
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1
1 Total Al
V
1
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CO
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j
1
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1
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1 Dissolved Mn
|
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CO H
6 .1
2 'g
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0 PQ.
CD (o -
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CO 0 |c
15" 3*2
90
- -I- i :~
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O5
O5
m
CM
C3
I
co
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.
CO
CO
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s
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cn
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to
CM
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o cn
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in
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00
Si
o
CM
in
cn
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CO
1
Alkalinity
o
co
m
CM
cn cn
o o
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co co
CM CM
CM CM
CO
o
CO
ft
f-
d
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CM
1
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73
1
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CO
oo
00
00
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00
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CO
CM
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00
0
cn
^
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1
o
V"
8
co
as
V V
00 CO
D 00
CM T-
SCM
co
cn
m
o
cn
&
CO
o
CO
8
00
CO
1
I
X
3
ฃ
8
CM
fc
00
t
^ I-.
**
cn h-
co in
* h-
10 (-
t- en
CM i-
CM
CM
in
S
CM
CO
CM
CO
CO
CO
o
o
CM
1
g
Ca Hardm
o
CO
T~
T
00
T-
CM CO
ฃฃ
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1
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o
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in
o
en
^
1
8
s
as
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m
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CO
o
CO
CM
cn
en
CM
cn
in
in cn
co co
0 O
CM CM
m o
CO CO
CO CO
cn
CO
CO
&
5-
i
If
CO
CM in
in in
T- |-~
Si Si
c- o
cn o
CM CO
1
"CD"
S
"o
CO
i
CO
<
o o
V V
o o
V V
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1
I
..
As (partic
CO CM
o o
CO CO
o o
en T-
CO I--
CM CM
1
!
cn CM
* in
00 *
CM Si
cn h-
CM CM
i
!
CO
cn
a
T-
iV
^
co
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p
:^
CO T-
cn cn
co in
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in
^ ^
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o
,
CO
m
^
v
1
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S
CM
CM
co
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O
CO
in
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CM
9*9
11
cn o
in co
CM CJ
CO
CO
o
CM
CM
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1
t--
00
CM
T-
^.
CM
OO
*
CO
cn oo
CO CO
in CM
en o>
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II
CO
CO
co
CO
CO
in
^
1
c
v v
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CO CO
^ ^
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^
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o o
CO CO
V V
o o
co in
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i
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CO O
h- co
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f- O
CO OO
i, i ,
1
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u.
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I
CD
O.
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91
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o
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r i 1
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1
1
1
1
4
- ;
i" ;
1
ง
o
!
'i' 'if !iJ
." '
CO
''i''1 ; ii
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1 . ' ' 'ii
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cn
T
q
CO
V
CO
CO
-
CO CO
*- -^
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58
r~ in
o in
"3- CO
CO
8
ฃ
V
1
Total Al
"i" : '
i1 ,
q
CM
CO
c\j"
CO
5
ง
in
CO
00
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CM CM
in in
co co
S CM
cn co
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cn
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o>
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1
: "1 '
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o
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q
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co
CO
CO
o cn
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o in
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in ซ-
CO CO
cn
cn
CO
CO
CO
1
Total Mn
,' ill'1! !
T- T-
V V
CM i-
CO CO
V V
_I
i
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i f
;
o o
w
a in
CM" CM"
1
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LL
1
5
ASK
i
CM T-
co co
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m co
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c
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5
1 i ,,ซ ' ^^^;/l^^|l:ii5ll .''k:'i"T!
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8-
o ^
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Q.
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co
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n 5
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ง
U5
t
?
CO
CM
co
1
w
cu
i
10
to
CM
2
0
88
cn CM
? ?
O CM
T O
CM CM
cn
^
^*.
s
1
8
CM
5
CM
cn
in
s
g
I"
Ca Hardness
O
CM
in
8
\*
i in
> 0
j?
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o
CM
S
CO
CO
cn
CM
CO
CM
^
1"
ii
Mg Hardness
S3
t
CM
CO
^
^
CO
CM
co
8
CD O
T- C\
^ ^
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^ CO
cn in
CO *
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r-
co
in
co
cn
CM
i
I
^
^- ^*
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CO O)
00 CO
^N
S!w
4
CD
As (total solub
D O
O O
V V
CO CO
1- CM
1
,_,
As (particulate
in *
0 0
in in
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in in
CMS!
1
1
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V
CO
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5
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m [^
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co
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o
o
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1
in
CM
4
s.
I
^
co
f-
cn
|
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s
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CM
CO
CM CO
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^^
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5S
^
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CO
CO
4
Total Mn
CD CM
CM CM
cn cn
m m
co co
V V
1
Dissolved Al
o o
w *w
V V
* co
CO C\
in in
CM CM
4
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cn c
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co cn
i-~ f-
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4
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c
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B
fe
II
LL
|
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CD -
o ts
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u
93
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0.
z
u.
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u.
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a.
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a.
z
gl
1 Sampling \jxs
Parameter
1
CM
S
1
oo a
II
ss
T3
'B
cq
00
co
co'
CM
r^
CO CO
co co
CO CO
cri cn
CM CM
r^ h-
co
cn
in
CO
CO
c-
00
(^
co
CO
CM
r--:
i.
s
T
CO
in
o
CO
5 in
4 ^
10
ss
CO CM
a
1
SI
CM
3
5!
CM
in
CO
8
CO
V
Total Hardness
iv.
S
CM
d
r-~
fe
05 CM
S3
in CV
t^ CD
co co
f- CM
X> CC
CM
co
8
in
CM
^
f-
8
s
1
Ca Hardness
O
JE
00
* CO
8?8
C~ 00
sis
CO ,3.
c-.
i^
00
CO
T-
m
CM
en
Y
8
in
55>
Mg Hardness
C-;
CM
CO
CO
CM
CO
8
in
CM
f-
cS
CO
s
co cvi
00 CO
-* co
t- O
co co
i- CM
O Cn
* co
CM'
CN
EM
in
CO
CO
o>
a.
3
f- h-
CO CO
in in
O t-
co co
CO CM
??
1
As (total soluble)
ฐ^
en i-
ฐ<3
^^
i
As (particulate)
ii:1'
CO CO
0 O
* o
1^ 1^
co co
1
ฅ
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CO 03
CO
<
;!!: ''
o
CO
cn
S
CO
(N
o
CM
co
CO
CM
in
co cn
CM CO
Tf CO
CM 1^
in *
V 'v
cn
N
in
ง
^
1
1 Total Al
...
lit!
.: !
CO
in
in
5
s
CD
CM
CO
m
ง
i'
co"
88
V V
in in
t s-
CO CO
i- OO
in *i-
cJcJ
CO
CO
CO
g
PI
in
CM"
1
ฃ
I
'' 1 :
co
CO
CO
oi
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h-
CO
CM
K
r-~
i^
* >*
i- O
;=;:
II
CO
si
CM
CO
^
^)
a.
Total Mn
1 !:
V V
in T-
co *
CM CO
'v V
1
Dissolved Al
O O
co co
V V
o o
CO CO
V V
CM" CM"
i
Dissolved Fe
N i~-
0 0
CM CM
* *
CM i-
n in
1
Dissolved Mn
1 i
i
c.
o
1
S
H
1
II
U-
<
I
1
V, 11
Ou.
OD-
S%
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94
-------
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CM
O
E
ca
a_
ro
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CO
(73
E
TO
o
3
CO
CD
cr
15
o
03
5
O4
6
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A
n
&
/
X
,$,
O3 '
n
ป
,ง;
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V;IV''*
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t^=
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TS
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'% Sampling Da
,u/
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rgff
% "'^
>,/*"V
f ^
i-
^
;'
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;'?,'
<"Vฐ r*
*
: u. .
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ss' '
a
J
S.1
Q.^
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CM
r^
CO CO
CO CO
h- r^
CO CO
CM i-
K i--^
CM
0>
05
CO
CO
t^
CM
r-
1^
CO
o
05
CM
h-:
a.
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CO
1
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o
co
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co co
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00 O5
ss
CO
J
r-~
8
co
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co
fe
T
CM
CM
o
co
1
I
ฃ
O5
CO
*
l^~
CD
co
0
s
t ^
o P
CD *
35 ro
XI CO
T T-
05
5-
h-
O5
in
fe
fe
en
s
O5
o
in
O)
i
Ca Hardness
N
*
ca
co
ฃ
ง
* CO
T" T
o> f-
o o
ex> r-
I-- f
T" T
CO
O
ฃ
CO
T
o>
ง
3
m
1
II
II Mg Hardness
t co
* *
o en
* CO
o
CO
CO
&
05
s
1
I
3
co l^
r~ t^
* CM
N CM
CO CO
CO CO
CO CO
CM CO
co8
1
As (total soluble)
,_ T_
"??
CO CM
CM in
CM T-
O CO
CM m
en in
1
As (particulate)
h- CO
03 i-
O i-
in r-
ss
O) CO
88
*&
3
I-- in
in co
in i-
co co
CM CM
tซ- CO
* CO
^ ^
o o
V V
1
>
3
in
co
co
te
"v
1--
cd
CD
fci
i
't
^ ^v
in co
in o
CM CO
^ 'v
^v 'v
o
in
CM
in
CO
;s
1
:<
I
o
CO
V
i
^
in
CM"
*
ง
CO
CO
I--
8
CM"
o o
^^
CO 0
? 5-
in 'tf-
* 00
O5 CO
CM"CO"
O5 1-
co co
CM" CM"
o
V
1
CM"
1
ฃ
1
CO
co
co
t^
s
^~
*
(^
CO
CM
s
CM *
CM 1-
CO O5
05 ro
a> i-
co *
ss
CM
CO
CD
CO
in
CO
T-
1
c
1
V 'v
^v 'v
V V
^v ^v
1
Dissolved Al
88
V V
88
V V
T- h-
O> t-
co o
co in
* *
CM" CM"
ll
Dissolved Fe
en T-
o *-
.,_ T-
CM CM
2<2
co *
CO CO
1 T
"a
Dissolved Mn
after filtration
ii
!4
b~
g
?
f
~2
Q.
II
LL
O.
O
1
(D
CO
. II
Orr
o <
c3t;
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I ') !';!
C
T3
O
O
e
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Q.
TO
I
<ฃ.
t
- ' : ::-
1
I
1
- ' "
' :":"-.:
$
o
:::::
1
"
&
1 ! = ==J
Sampling Da
ife
u_
0.
Z
$
u_
a.
2
%
u.
Q-
tt
<
2
U.
<
u.
a.
2 ;
t
13
Sampling Loca
Parameter
*
03
CM
a
V-
*
CO 00
II
8S
T <ซ
CM
CD
t^
O>
CO
CM
"*
O)
03
00
Si
CO
o
*
1
ฃ?
'd
1
5
*
O
CO
o
s
T- O
ui in
CM O
?ฃ?'
ฐ. ฐ.
m co
CO
o
CM
CO
CO
CD
m
CD
CM
00
o
EM
3
ฃ
o
S
3
CD
CO
in
CO
CM
h-:
O CD
CD 03
CO CO
CD CO
CM CM
1^ (^
CD
CO
CD
N-
f-
CM
r-^
i^
03
CO
03
N:
Q.
UJ
O
Si
EM
co
r~- co
co co
3ง
T- V
[-~ in
o
co CD
in if>
* CM
STi-
CO
o r-
CM CO
CM >-
CO CO
to
CO
I
$
CM O
1^ CD
CD CO
CM CM
CM CM
T- CD
CO CO
CO CO
CO t^
S3
ll
As (total soluble)
T- CO
?ฐ
1^ 1^
CO CO
CM i-
0t
CM
S'
^v
00
CD
CM
CO
ง
CO
Sf
CO
T- T
^~ V
0 t^
CD N
*
^ CM
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V "v
o
CO
CO
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v
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a.
<
H
0
fe
1
i
CM"
s
CO
in
in
g
CM"
t^ CO
Sc^
sฃ
St-~
K CD
CM" CM"
CM *
O> f
CM" CM
o
co
V
1
ff
CO
CM"
_i
D)
i
Total Fe
co
o
S
ฃ
CD
f-
1^
ง
in in
CM CM
CO CM
SSi
fcS
T If
^p
h~
r~
cj
CO
f~
^
c
ฃ
T~ T
"v V
'v V
V V
T7 'v
^
Dissolved Al
i
o o
co co
V V
co co
V V
CM CO
CO CO
* h-
Sen
CO
CM" CM"
^
Dissolved Fe
r^ co
CM CM
CM CM
CD CO
|-~ CO
-> 1
CO CO
1
Dissolved Mn
ifter filtration
II
u.
<
c
g
^
1
0.
ll
LL.
0.
O
?
S
a) As CaCO3.
N = inlet; AR = afte
96
-------
-------
United States
Environmental Protection Agency
National Risk Management
Research Laboratory, G-72
Cincinnati, OH 45268
Please make all necessary changes on the below label,
detach or copy, and return to the address in the upper
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Penalty for Private Use
$300
EPA/600/R-00/063
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