_ „ United States
i Environmental Protection
* Agency
Office of Research and
Development
Washington, DC 20460
EPA/600/R-01/021
March 2001
http://www.epa.gov
Laboratory Study on the
Oxidation of Arsenic III to
Arsenic V
• \x
As (III)
As(V)
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EPA/600/R-01/021
March 2001
Laboratory Study on the Oxidation
of Arsenic III to Arsenic V
by
Ganesh Ghurye
Dennis Clifford
University of Houston
Houston, TX 77204-4791
EPA Contract 8C-R311-NAEX
Project Officer
Thomas Sorg
Water Supply and Water Resources Division
National Risk Management Research Laboratory
Cincinnati, OH 46268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
Printed on Recycled Paper
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Disclaimer
The information in this document has been funded by the United States Environmental
Protection Agency (EPA) under Contract No. 8C-R311-NAEX to the Department of
Civil and Environmental Engineering at the University of Houston. It has been subjected
to the Agency's peer and administrative reviews and has been approved for publication as
an EPA document. Mention of trade names or commercial products does not constitute
an endorsement or recommendation for use.
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Foreword
The United States Environmental Protections Agency (EPA) is charged by Congress with
protecting the Nation's land, air, and water resources. Under a mandate of national
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pollutants affect our health, and prevent or reduce environmental risks in the future.
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for investigation of technological and management approaches for preventing and
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focus of the Laboratory's research program is on methods and their cost-effectiveness for
prevention and control of pollution to air, land, water, and subsurface resources;
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advancing scientific and engineering information to support regulatory and policy
decisions; and providing the technical support and information transfer to ensure
implementation of environmental regulations and strategies at the national, state, and
community levels.
This publication has been produced as part of the Laboratory's strategic long-term
research plan. It is published and made available by the 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
in
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Abstract
A one-year laboratory study was performed to determine the ability of seven oxidants to
oxidize As(III) to As(V). These included chlorine, permanganate, ozone, chlorine
dioxide, monochloramine, a solid-phase oxidizing media, and 254 nm ultraviolet light.
Chlorine and permanganate rapidly oxidized As(III) to As(V) in the pH range of 6.3 to
8.3. Dissolved manganese, dissolved iron, sulfide and TOC slowed the rate of oxidation
slightly, but essentially complete oxidation was obtained in less than one minute with
chlorine and permanganate under all conditions studied.
In the absence of interfering reductants, ozone rapidly oxidized As(III). Although,
dissolved manganese and dissolved iron had no significant effect on As(III) oxidation,
the presence of sulfide considerably slowed the oxidation reaction. The presence of TOC
had a quenching effect on As(III) oxidation by ozone, producing incomplete oxidation at
the higher TOC concentration studied.
Only limited As(III) oxidation was obtained using chlorine dioxide, which was probably
due to the presence of chlorine (as a by-product) in the chlorine dioxide stock solutions.
The reason for the ineffectiveness of chlorine dioxide was not studied.
Preformed monochloramine was ineffective for As(III) oxidation, whereas limited
oxidation was obtained when monochloramine was formed in-situ. This showed that the
injected chlorine probably reacted with As(III) before being quenched by ammonia to
form monochloramine.
Filox, a manganese dioxide-based media, was effective for As(III) oxidation. When
dissolved oxygen (DO) was not limiting, complete oxidation was observed under all
conditions studied. However, when DO was reduced, incomplete oxidation was obtained
in the presence of interfering reductants. The adverse effect of interfering reductants was
completely eliminated by either (a) supplying enough DO or (b) increasing the contact
time. In addition to oxidizing As(III), the Filox media also removed some arsenic by
adsorption, which diminished greatly as the media came into equilibrium with the
As(HI)-spiked synthetic water.
UV light alone (254 nm) was not very effective for As(III) oxidation. Significant
oxidation was observed only at very low flow rates representing 0.6 - 2.5% of the rated
capacities of the two UV sterilizer units tested. However, as reported in a patented
process, complete oxidation by UV light was observed when the challenge water was
spiked with 1.0 mg/L sulfite.
iv
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Contents
Foreword iii
Abstract iv
Figures viii
Tables ix
Abbreviations and Acronyms x
Acknowledgments xi
1. Introduction 1
1.1 Background 1
1.1.1 Previous Studies 1
1.2 Oxidants Evaluated 2
1.3 Oxidant Stoichiometry 2
1.3.1 Chlorine 2
1.3.2 Permanganate 3
1.3.3 Ozone 4
1.3.4 Chlorine Dioxide 4
1.3.5 Monochloramine 5
1.4 Research Objectives 5
2. Materials and Methods 6
2.1 Synthetic Test Water Composition 6
2,2 Interfering Reductants 6
2.3 SpeciationMethod..... 6
2.4 Chemical Oxidation Experiments 7
2.4.1 Reactor Design 7
2.4.2 Testing Reactor Set-up 11
2.4.2.1 Arsenic(V) Retention. 11
2.4.2.2 Arsenic(III) Passage 11
2.4.2.3 System Dead Volume 11
2.4.2.4 Oxidant Mixing Efficiency 11
2.4.3 Oxidation Conditions 12
2.4.3.1 pH of Operation 12
2.4.3.2 High- and Low-DO Experiments 12
2.4.3.3 Oxidation Experiments with TOC 13
2.4.3.4 Low Temperature (5 °C) Oxidation Experiments 13
2.5 Solid-Phase Media (Filox) Experiments 13
2.5.1 Pretreatment of Filox Media 13
2.5.2 Preparation of Low- andHigh-DO Synthetic Water 14
2.5.3 Procedure for Variable-EBCT and Variable pH Experiments 14
2.5.4 Procedure to Stabilize Arsenic Removal by Filox Media 14
2.5.5 Procedure for Low-DO Filox Experiments 15
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2.6 UV Oxidation Experiments 15
2.6.1 Unit 1: 0.5 gpmUV Sterilizer Unit 15
2.6.2 Unit 2: 1.0 gpmUV Sterilizer Unit 16
2.7 QA/QC •. 16
2.7.1 Arsenic Standards 16
2.7.2 Routine Arsenic Analysis 17
2.7.3 Arsenic Calibration Curve 17
2.8 Analytical Methods 18
3. Results and Discussion 19
3.1 Reactor Set-up Test-Results 19
3.1.1 Arsenic(V) Retention 19
3.1.2 Arsenic(III) Recovery 20
3.1.3 Dead Volume in Oxidation Reactor Set-up 21
3.1.4 Mixing Efficiency in Oxidation Reactor 22
3.2 Chlorine Test Results 23
3.2.1 Effect of pH on Chlorine 23
3.2.2 Effect of Dissolved Manganese and Iron on Chlorine 25
3.2.3 Effect of Sulfide on Chlorine 25
3.2.4 Effect of TOC and Temperature on Chlorine 25
3.3 Permanganate Test Results 25
3.3.1 Effect of pH on Permanganate 26
3.3.2 Effect of Dissolved Manganese and Iron on Permanganate 27
3.3.3 Effect of Sulfide on Permanganate 27
3.3.4 Effect of TOC and Temperature on Permanganate 28
3.4 Ozone Test Results 28
3.4.1 Effect of pH on Ozone 29
3.4.2 Effect of Dissolved Manganese and Iron on Ozone 30
3.4.3 Effect of Sulfide on Ozone 30
3.4.4 Effect of TOC and Temperature on Ozone 30
3.5 Chlorine Dioxide Test Results 31
3.5.1 Effect of pH on Chlorine Dioxide 31
3.5.2 Verifying Chlorine Dioxide Stock Concentration 33
3.5.3 Fe(H) Oxidation with Chlorine Dioxide 34
3.5.4 Increasing Stoichiometric Dose of Chlorine Dioxide 34
3.5.5 Effect of Dissolved Manganese and Iron on Chlorine Dioxide 34
3.5.6 Effect of Sulfide, TOC and Temperature on Chlorine Dioxide 34
3.6 Monochloramine Test Results 35
3.6.1 Effect of pH on Monochloramine 35
3.7 Solid-Phase Oxidizing Media (Filox) 36
3.7.1 Filox: Effect of EBCT with High-DO 36
3.7.2 Filox: Effect of pH with High-DO 39
3.7.3 Filox: Effect of DO in Absence of Interfering Reductants 40
3.7.4 Filox: Effect of Interfering Reductants 40
3.7.4.1 Low-DO Synthetic Water at l.SminEBCT 40
3.7.4.2 Low-DO Synthetic Water at 6.0 min EBCT 40
VI
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3.7.4.3 High-DO Synthetic Water at 1.5 minEBCT 40
3.7.5 Filox: Effect of Low Temperature in low-DO Synthetic Water 41
3.8 UV Oxidation Results 41
3.8.1 Unit 1—R-CanUltraviolet, 0.5 gpm 41
3.8.2 Unit 2—Atlantic Ultraviolet, 1.0 gpm ...42
4. Summary and Conclusions 43
5. References 45
6. Appendix A. Preconditioning and Regeneration of IX Filter 48
A.1 Manufacturer Recommended Preconditioning 48
A.2 IX Filter Regeneration—UH Method 48
Appendix B. Testing Oxidation Reactor Set-up 49
Appendix C. Variable-DO Experiments 50
C.I High-DO Chemical Oxidation Experiments 50
C.2 Low-DO Chemical Oxidation Experiments 51
Appendix D. Solid-Phase (Filox) Experiments 52
D.I Variable-EBCT and Variable-pH experiments 52
D.2 Low-DO Filox Experiments 52
Appendix E. Chlorine Oxidation Data 54
AppendixF. Permanganate Oxidation Data 57
Appendix G. Chlorine Dioxide Oxidation Data 60
Appendix H. Monochloramine Oxidation Data 63
Appendix! Ozone Oxidation Data 65
Appendix J. Filox Oxidation Data 68
Appendix K. UV Oxidation Data 70
Appendix L. Preparation of As(III) Stock Solution 72
Appendix M. QCData 73
Vll
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Figures
2-1 Schematic for Oxidation Reactor
2-2 Elevation View of Oxidation Reactor
2-3 Simplified Plan View of Oxidation Reactor
2-4 Schematic for Solid-Phase (Filox) Oxidizing Experiments
2-5 Schematic for UV-Oxidation Experiments
2-6 Typical Arsenic Calibration Curve
3-1 50 |ig/L-As(V) Retention by IX Filter
3-2 1000 ug/L-As(V) Retention by IX Filter
3-3 50 |ig/L-As(III) Recovery from IX Filter
3-4 1000 ug/L-As(III) Recovery from IX Filter
3-5 Estimation of Dead Volume in the Reactor-Set-up
3-6 Mixing Efficiency in Oxidation Reactor
3-7 Effect of pH on As(III) Oxidation with Free Chlorine
3-8 Effect of Sulfide on As(III) Oxidation with Free Chlorine
3-9 Effect of pH on As(IH) Oxidation with Permanganate
3-10 Effect of Sulfide on As(III) Oxidation with Permanganate
3-11 Effect of pH on As(III) Oxidation with Ozone
3-12 Effect of Sulfide on As(III) Oxidation with Ozone
3-13 Effect of TOC on As(III) Oxidation with Ozone
3-14 Arsenic(III) Oxidation with Chlorine Dioxide
3-15 Arsenic(III) Oxidation with Monochloramine
3-16 Effect of EBCT on Filox Media
3-17 Filox Media Equilibration
3-18 Effect of pH on As(III) Oxidation with Filox Media
Page
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9
10
14
15
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19
20
21
21
22
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24
25
27
28
29
30
31
33
35
38
39
40
Vlll
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Tables
2-1 Composition of Synthetic Test Water
2-2 Interfering Reductants
2-3 Previous EPA Standards
2-4 Analytical Methods
3-1 Free Chlorine Experiments
3-2 Permanganate Experiments
3-3 Ozone Experiments
3-4 Chlorine Dioxide Experiments
3-5 Chlorine Dioxide Assays
3-6 Monochloramine Experiments
3-7 Filox Experiments
3-8 UV Oxidation Experiments
E-l Residual As(III) Cone, vs Time for Chlorine Experiments
F-l Residual As(III) Cone, vs Time for Permanganate Experiments
G-l Residual As(III) Cone, vs Time for Chlorine Dioxide Experiments
H-l Residual As(III) Cone, vs Time for Monochloramine Experiments
1-1 Residual As(III) Cone, vs Time for Ozone Experiments
J-l Residual As(III) vs Effluent As Concentration for Filox Experiments
K-l Residual As(III) Cone, for UV Experiments
M-1 Results of QC Analysis
M-2 Results of WS Standards Analysis
M-3 Recoveries of Spiked WS Standards
Page
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6
16
18
24
26
29
32
34
35
37
41
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58
61
64
66
69
71
74
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85
IX
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Abbreviations and Acronyms
AWWA American Water Works Association
DO Dissolved Oxygen, mg/L
DPD N,N-diethyl-p-phenylenediamine
EBCT Empty Bed Contact Time (media volume/flow rate), min
EPA US Environmental Protection Agency
FIAS Flow Injection Analysis Hydride Generation System
GFAAS Graphite Furnace Atomic Absorption Spectrophotometer
GPM Gallons/min
HOPE High Density Polyethylene
IR Interfering Reductant
MCL Maximum Contaminant Level
MDL Method Detection Limit
MPT Nominal Pipe Thread
NRMRL National Risk Management Research Laboratory
PAO Phenyl Arsenic Oxide
PRV Pressure Relief Valve
QA Quality Assurance
QAPP Quality Assurance Project Plan
QA/QC Quality Assurance/Quality Control
SDWA Safe Drinking Water Act
SM Standard Methods
SR Stoichiometric Ratio, ug oxidant/ug reductant
TOC Total Organic Carbon
UH University of Houston
UV Ultraviolet
WAL Work Assignment Leader
WAM Work Assignment Manager
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Acknowledgments
This research was funded by the US EPA under EPA Order Number 8C-R311-NAEX.
The authors are grateful for the technical and administrative support of Tom Sorg, US
EPA Research Engineer. Anthony Tripp, a doctoral candidate at the University of
Houston is gratefully acknowledged for serving as the QA/QC Officer and for his
considerable technical assistance throughout this study.
XI
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1. Introduction
1.1 Background
Arsenic (As) is a metalloid that is
naturally present in drinking water in a
variety of forms (organic and inorganic),
oxidation states, and valences (Ferguson
and Gavis, 1972). Inorganic arsenic
predominates in drinking water and is
present as arsenate (As(V)) and arsenite
(As(ni)). Under pH conditions of 6-9,
As(V) exists as an anion while As(DI) is
fully protonated and exists as an
uncharged molecule (Clifford and
Zhang, 1994).
While any future revisions in the arsenic
MCL will likely target total arsenic, the
speciation of arsenic (HI or V) is
significant because of differences in
arsenic removal efficiencies by various
treatment techniques. As(V) is generally
more efficiently removed than As(m),
which is poorly removed using treatment
processes such as ion exchange
(Clifford, 1999, Clifford et al., 1998a,
1997), iron coagulation followed by
microfiltration (Clifford et al., 1998b;
Ghurye et al., 1998; Hering et al., 1996a,
1996b), and activated alumina
adsorption (Clifford, 1990, 1986;
Clifford et al., 1998b; Hathaway and
Rubel, 1987). Hence, for drinking water
supplies containing significant
concentrations of As(DI), preoxidation
of As(ni) to As(V) is mandatory for
high arsenic removal.
1.1.1 Previous Studies
Frank and Clifford (1986) studied the
oxidation of As(ni) to As(V) using
chlorine, monochloramine and oxygen.
They determined that the oxidation of
As(IH) by chlorine was very rapid. A
1.0 mg/L free chlorine dose was able to
oxidize 100 |ig/L As(m) in less than 5
seconds. Monochloramine was able to
oxidize only a fraction of the initial
As(ni) present, possibly because
chlorine injected in the presence of an
excess of ammonia to form
monochloramine, was responsible for
As(HI) oxidation rather than
monochloramine. Oxygen was found to
be ineffective for As(HI) oxidation.
Amy et al. (2000) studied the use of
chlorine, ozone and permanganate for
As(ni) oxidation. This study used
excess (over As stoichiometry) ozone
and stoichiometric doses of chlorine and
permanganate. All three oxidants
proved effective although less than
100% As(IH) oxidation was obtained
with chlorine and permanganate. This
was probably the result of NOM (0.2 -
2.3 mg/L) presenting a competing
oxidant demand. Although higher doses
of chlorine and permanganate were not
tested, the authors concluded that the
provision of these oxidants in
stoichiometric excess would result in
complete conversion of As(m) to As(V).
Oxidation of As(IH) to As(V) by solid-
phase oxidants such as birnessite (8
MnOa) has also been reported by
Oscarson et al. (1983), Moore et al.
(1990), Driehaus (1995), and Scott and
Morgan (1995). These studies generally
concluded that birnessite directly
oxidized As(IH) to As(V) through a
surface mechanism and that the
adsorption of As(ni) to the oxide surface
was the rate-limiting step. Additionally,
Scott and Morgan (1995) concluded that
dissolved oxygen had no effect on the
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rate of the oxidation reaction. However,
they did not study the effect of
interfering reductants on As(m)
oxidation. As will be shown later in this
report, we observed no effect of DO on
As(III) oxidation in the absence of
interfering reductants. We did, however,
observe that the DO level had a
significant detrimental effect on As(ni)
oxidation in the presence of interfering
reductants.
As(ni) oxidation has also been studied
by other researchers using a variety of
techniques including electrochemical
oxidation (Catherine, 1967), oxidation
by electrogenerated iodine (Johnson and
Bruckenstein, 1968), oxidation by
peroxodisulfate (Gupta, et al., 1984 and
Nishida and Kimura, 1989), oxidation by
perchloric acid (Everett and Skoog,
1971), oxidation by chromic acid (Sen
Gupta and Chakladar, 1989), and
oxidation by hexacyanoferrate(m)
(Mohan et al., 1977). These methods
were considered unsuitable for As(ni)
oxidation in drinking water and hence,
were not investigated in this study.
1.2 Oxidants Evaluated
Oxidation experiments were performed
in the aqueous phase via the addition of
oxidants such as chlorine or ozone to a
solution containing As(IH) or by
contacting the As(nT)-containing
solution with a solid-phase oxidant. A
solid-phase oxidant is typically a media
that has the oxidant immobilized on its
surface and such media may be used in
packed columns through which the
As(IH)-containing solution is passed at a
specified flow rate or empty bed contact
time (EBCT). The use of UV radiation
to oxidize As(ni) to As(V) was also
studied at a wavelength of 254 nm, using
two commercially available UV
disinfection units.
1.3 Chemical Oxidant
Stoichiometry
Reaction stoichiometries of the various
chemical oxidants with As(in) and
potentially interfering reductants are
summarized below.
1.3.1 Chlorine
For AsdED:
H3AsO3 + NaOCl
Na+ + Cr + H+
H2AsO4" +
(1)
50
In reaction (1), one mole of As(m)
requires 1 mole of NaOCl, which is
equivalent to one mole of Cfe. A
|ig/L As(m) solution contains 0.667
As(EI)/L (AW of As = 74.92).
Therefore, the stoichiometric
requirement of chlorine is 0.667 uM/L
or 47.4 jag Cb/L, and the stoichiometric
ratio (SR) of chlorine needed to oxidize
As(m) is 0.95 jig Cla/ng As(DI).
SR = 0.95 ug CVug As(ffl)
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ForFedl):
2Fe(OH)3 (s) +Cr +5H+
SR = 0.64 jig Cl2/|ag Fe(E)
For Mn(IT):
(2)
MnO2 (s) +C1" +3IT
SR = 1.29 |ag Cl2/|ag Mn(E)
For Sulfide:
(3)
MS' + HOC1
+ CF + H20
(4)
SR = 2.21 jig Cl2/|ag S2'
pH Range = 5-9
Optimum pH = 9.0
(5)
SR = 8.86 |ag Cl2/|ag S2'
pH Range = 5-9
Optimum pH = 6.0
The chemistry of the oxidation of sulfide
is extremely complex. Reportedly, the
oxidation proceeds to form either
elemental sulfur, sulfate, or both (White,
1986). Equations (4) and (5) for the
oxidation of sulfur with chlorine were
obtained from White (1986). The
oxidant doses used in the presence of
sulfide were either three- or 10-times the
stoichiometric requirement based on
As(m) alone. Since the As(ni)
concentration in the presence of
interfering reductants such as sulfide
was always 50 |ag/L, the resultant
oxidant doses used were low in relation
to the sulfide concentrations of 1.0 and
2.0 mg/L, Oxidation reactions, similar
to equation (4) for chlorine dioxide,
permanganate, ozone, and
monochloramine were derived based on
oxidation of sulfide to elemental sulfur
only.
1.3.2 Permanganate
For AsdTf):
3H3 AsO3 + 2MnO4- -» 3H2AsO4" + (6)
SR = 1.06 |ag MnO47|ag As(HT)
ForFeOD:
3Fe2+ + Mn04- +7H2O -»
3Fe(OH)3 (s) + MnO2 (s) + 5H+
SR = 0.71 jag MnO47|ig Fe(II)
For Mn(TD:
3Mn2+ + 2MnO4- +2H2O -»•
5MnO2 (s) + 4H+
SR = 1.44 |ag MnO47|ag Mn(H)
For Sulfide:
3HS- + 2MnO4- + 51^^ 3S°i +
2MnO2(s) + 4H20
SR = 2.48 |ag MnO47ug S2'
(7)
(8)
(9)
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1.3.3 Ozone
For AsOID:
H3AsO3 + O3 -» H2As04" +
O2 + H"(@pH6.5)
H3As03 + 03 -> HAs042' +
O2 + 2H+(@pH8.5)
SR = 0.64 ug O3/ug As(m)
ForFeOD:
2Fe2+ + 03 (aq) + 5H2O ->
2Fe(OH)3 (s) + O2 (aq) + 4H+
SR = 0.43ugO3/ugFe(II)
ForMnOD:
Mn02(s)
SR = 0.88 jig O3/ug Mn(E)
For Sulfide:
HS" + O3 (aq) + H"
O2 (aq) + H2O
SR=1.50ug03/ugS2
(10)
(12)
(13)
(14)
1.3.4 Chlorine Dioxide
Oxidation by chlorine dioxide can occur
via a 1- or 5-electron transfer with the
conversion of C1O2 to C1O2" or Cl",
respectively. Knocke (1990) determined
that chlorine dioxide oxidized Mn(n) via
a 1-electron transfer whereas it oxidized
Fe(H) via a 5-electron transfer. When
calculating an appropriate chlorine
dioxide dose for As(m), a conservative
1-electron transfer was assumed.
However, theoretical stoichiometric
ratios for both 1-and 5-electron transfer
mechanisms are shown below.
•%
For As(m):
H2O-»-H2AsO4- +
2C1O2" + 3H+ (1-electron transfer) (15)
5H3As03 + 2C102 + H20 -»• 5H2AsO4"
+ 2C1" + 7H1" (5-electron transfer) (16)
SR=1.80 u
transfer
SR=0.36 u
transfer
For FeOD:
ClO2/|ig As(HI) for 1-electron
ClO^ug As(m) for 5-electron
+ C1O2 + 13H2O
5Fe(OH)3(s) + Cr
SR=0.24 ug
transfer
For Mndl):
(17)
Fe(E) for 5-electron
+ 2C1O2 + 2H2O -»
MnO2 (s) + 2C1O2- + 4H+
(18)
SR=2.45 ug CICVug Mn(E) for 1-electron
transfer
For Sulfide:
HS' + 2C1O2 -»• S°
1 electron transfer
2C102'
(19)
5HS' + 2C1O2 + 3ET -> 5S°i + (20)
2C1" + 4H2O (5 electron transfer)
2"
SR = 4.21 ug ClO^ug S" for 1-electron
transfer
SR = 0.84 ug ClO2/ug S2" for 5-electron
transfer
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Chlorine dioxide was prepared according
to the general procedure described in
Standard Methods with two
modifications (White, 1986) to increase
the yield of chlorine dioxide and
decrease the background concentrations
of chlorine and chlorite. These
modifications were (a) doubling the
reagent concentrations of sodium
chlorite and sulfuric acid and (b) pre-
cooling the receiving solution
1.3.5 Monochloramine
For AsCIII):
H3As03 + NH2C1 + H2O
HAsO42"
(21)
SR = 0.69 ug NH2Cl/ug As(ffl)
For Fe(n):
2Fe2+ + NH2C1 +6H2O ->•
2Fe(OH)3 (s) + NH4+ + Cl' + 4IT
SR = 0.46 |ag NH2Cl/ug Fe(H)
For MnOD:
Mn2+ + NH2C1 +2H2O ->
(22)
MnO2 (s) + NHU+ + Cl" + 2H+
SR = 0.94 |ag NH2Cl/ug Mn(H)
For Sulfide:
S2" + NH2C1 +2BT -»
sU + NHU+ + cr
(23)
1.4 Research Objectives
The overall objective of this study was
to determine the effectiveness of five
chemical oxidants, a solid-phase
oxidizing media, and UV radiation in
oxidizing As(m) to As(V) under a
variety of environmental conditions.
Potentially interfering reductants such as
dissolved manganese, dissolved iron,
sulfide and TOC were studied as they
are typically present in arsenic-
contaminated waters. The specific
objectives of this study were as follows:
(1) Study the effectiveness of (a)
chlorine (b) permanganate (c) ozone, (d)
chlorine dioxide, (e) monochloramine,
(f) solid-phase oxidizing media and (g)
UV radiation (@254 nm) for the
oxidation of As(DI) to As(V).
(2) Determine the effect of pH, in the
range of 6.3-8.3, on the oxidation of
As(m) to As(V).
(3) Determine the effect of potentially
interfering reductants including
dissolved iron, dissolved manganese,
sulfide, and TOC, and the effect of low
temperature (5 °C) on the oxidation
process.
(24)
SR= 1.61 |ag NH2Cl/ugS
2-
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2. Materials and Methods
2.1 Synthetic Test Water
Composition
The composition of the synthetic test
water used to perform the oxidation
experiments is shown in Table 2-1. The
synthetic test water contained most of
the common ions found in surface and
ground waters.
Table 2-1. Composition of Synthetic Test Water.
Cations
Na+
Ca2+
Mg2*
Total
meq/L
3.3
2.0
1.0
6.3
mg/L
75.9
40.2
12.2
128.3
Anions
HC03"
S042'
cr
Silicate as
SiO2
meq/L
3.0
0.5
2.5
0.3
6.3
mg/L
183.0
24.0
88.8
20.0
315.8
Calculated TDS = 128.3 + 315.8 - 93 mg/L (loss of H2CO3 during evaporation) = 351.1 mg/L
2.2 Interfering Reductants
Synthetic water was amended with
potentially interfering reductants and
studied for their ability to affect As(III)
oxidation. The various interfering
reductants studied are listed in Table 2-2
along with their concentrations.
Table 2-2. Interfering Reductants.
Interfering Reductant
Concentration (mg/L)
Manganese (Mn(II))
Iron (Fe(II))
Sulfide (S2-)
Total Organic Carbon (TOC)
0.2
0.3, 2.0
1.0,2.0
1.4-6.9
2.3 Speciation Method
A 3M Empore anion exchange filter
(hereafter referred to simply as IX filter)
was used to speciate As(III)/As(V). The
filter was preconditioned according to
the manufacturers recommendations
(See Appendix A). Following the
manufacturers preconditioning
procedure, the IX filter was further
conditioned (UH Method—See
Appendix A) by acid regeneration and 1
M NaCl treatment to ensure that all
exchange sites on the filter were in the
chloride form prior to initial use or reuse
of the filter. Finally, excess 1 M NaCl
was rinsed from the filter with 0.005 M
NaCl. Analytical reagent grade
-------
chemicals were used throughout the
procedure.
2.4 Chemical Oxidation
Experiments
The procedures developed to design and
operate the oxidation reactor are
described here. The design of the reactor
is described in detail in Section 2.4.1.
Before the oxidation reactor could be
used to study any of the chemical
oxidants, the reactor set-up was tested to
(a) prove that the IX filters used in-line
with the oxidation reactor could
efficiently remove (>90% retention)
As(V), (b) prove that the IX filters
caused no inadvertent oxidation of
As(III) (>90% recovery), (c) determine
the dead volume in the reactor set-up,
and (d) determine the efficiency of
oxidant mixing in the reactor. Section
2.4.2 describes these tasks and the
procedures used to achieve them.
Section 2.4.3 describes the procedures
used during routine operation of the
oxidation reactor in either high- or low-
DO synthetic water. Finally, Section
2.4.4 discusses chemical oxidation
experiments performed to study the
effect of TOC and low temperature.
The procedures described in Sections
2.4.2 - 2.4.4 have some common steps,
irrespective of the objective of the
experiments. At the same time,
depending on the objective, there were
certain inherent differences in the
procedures used to operate the reactor.
For example, a larger sample volume
was desired when testing the reactor set-
up to determine the capacity of the IX
filter whereas a smaller sample volume
was required during oxidation
experiments. However, in the interest of
thoroughness, and at the risk of being
repetitive, the procedures are described
exactly as they were performed.
2.4.1 Reactor Design
The schematic design of the oxidation
reactor is shown in Figure 2-1 and the
elevation and plan views are shown in
Figures 2-2 and 2-3, respectively. To
simplify the drawing, the side port for
the pH probe is not shown in the plan
view. The reactor was equipped with a
pH probe, a nitrogen gas Met, a pressure
relief valve, a septa for injecting the
oxidant, and an outlet port. The reactor
was made of clear Plexiglas and
fabricated at the University of Houston
Machine Shop.
-------
Inject oxidant
@t=0
Pressure Relief
Valve
50 ug As(III)/L
1 L Total Volume
Magnetic Stirrei
On Bottom
Filter
Holder
Arsenic Oxidation
Reactor
60
50
Flow Rate = 5-25 mL/min
0.22 jam filter atop
3M Empore Filter
Fraction Collector/Sampler
40
30
20
10 sec
Figure 2-1. Schematic for Oxidation Reactor.
-------
l/2"-thick, Pressure
5"-square flanges , 1/8"NPT(F) , Relief Valve
i
cs
t— i
S
r«
"W
$
HH
1
»
i
i
i
i i N2Pressure , l/4"NPT(F)
V ' ' / ' 1
^ Ilf I 1/2"NPT(F) 1 ! /
;[ I /for Septa ] \f
i i \\ i i ! i
i ,i i 1,1
1/2" NPT(F)
for pH/Temp
probe
/
/
*
t \
' \
\
/"x
\
\
r
V
N
\
S_ _ Jl
N
N
i
3/4"
\
s..
\
\
\
\
\
X
.
V
N
*V
i >v
r
ill I i
1/2" Initial Liquid
jp^ Level 3 7/16*
500 mL
Final Liquid
Level \
\
\
>| 1 3/8"
210mL
J l
1 1/4"
"
i
5"
1/8" NPT(F)
\ t
\
Magnetic Stirrer
3"
Figure 2-2. Elevation View of Oxidation Reactor. Scale 1:1
-------
1/4" holes
5"
Figure 2-3. Simplified Plan View of Oxidation Reactor. Scale 1:1
10
-------
2.4.2 Testing Reactor Set-up
2.4.2.1 Arsenic(V) Retention
To ensure that > 90% As(V) was
retained by the IX filter, synthetic test
waters containing 50 and 1000 jj,g
As(V)/L were passed through the IX
filter. After the passage of a
predetermined volume of the As(V)-
containing solution, the IX filter was
regenerated and reused for further
testing. In all, six sequential runs were
performed. The first run was performed
using a fresh IX filter, whereas, the next
five were performed using a regenerated
IX filter. The procedures used during
testing are described in Appendix B.
2.4.2.2 Arsenic(III) Passage
To ensure that > 90% As(III) passed
through the IX filter, synthetic waters
containing 50 and 1000 |j.g As(III)/L
were tested. The procedures used for the
As(III)-passage experiments were the
same as those used for the As(V>
retention experiments described in
Appendix B.
2.4.2.3 System Dead Volume
The dead volume in the sampling system
consisted of the volume of tubing
connecting the oxidation reactor and the
filter holder plus the dead volume hi the
filter holder itself. The dead volume
inside the filter holder was necessary in
order to evenly distribute flow
throughout the surface of the filter. This
dead volume had to be wasted before the
contents of the reactor could be sampled.
The dead volume could not be calculated
directly because of problems in
calculating the void space within the
filter holder.
The dead volume of .the reactor set-up
was estimated by introducing a step-
increase in arsenic concentration (from
0-1000 |ig/L) into the well-mixed reactor
and then plotting the effluent arsenic
concentration vs volume passed through
the IX filter. Specifically, 500 mL of
arsenic-free synthetic test water was
placed in the reactor. The reactor was
pressurized and the necessary volume of
As(III) solution was injected into the
reactor at t = 0 to give a final
concentration of 1000 fig As(III)/L. The
reactor outlet valve was opened
immediately at t = 0 (flow rate = 5
mL/min) and samples (0.5 mL) were
collected in the fraction collector at an
interval of 6 seconds.
2.4.2.4 Oxidant Mixing Efficiency
When the oxidant was introduced into
the reactor, it was important that it
mixed instantaneously with the contents
of the reactor, so that inefficiencies in
mixing did not lead to erroneous
conclusions about the kinetics of As(III)
oxidation. Mixing of the oxidant was
assumed to be adequate if As(III) was
immediately oxidized by a large excess
(200-fold) of chlorine injected into the
mixed reactor. To determine the
efficiency of oxidant mixing in the
reactor, a 10 |j,g/L As(III) solution was
placed in the reactor. At time t = 0, a
chlorine dose of 2 mg/L (200-fold excess
over stoichiometric requirement) was
added to the reactor. The first 4 mL of
reactor effluent was wasted as dead
volume and the rest was collected in 2-
mL increments at 6 second intervals
(flow rate = 20 mL/min).
11
-------
2.4.3 Chemical Oxidation Conditions
Each initial As(DI) concentration was
tested with at least three concentrations
of each oxidant: three-, ten-, and one--
hundred times the stoichiometric amount
required to oxidize the As(]H) initially
present. Two levels of oxidant were
used in the presence of interfering
reductants: ten times based on As(]H)
concentration alone, or a higher dose of
three-times-stoichiometric based on
As(IE[) plus the interfering reductant.
However, if the lower dose successfully
oxidized greater than 90% of the As(ni)
initially present, then higher oxidant
doses were not tested. Initial As(HI)
concentration was 50 ug/L, unless
mentioned otherwise. Chlorine was
dosed in the form of sodium
hypochlorite (NaOCl) and reported as
mg/L chlorine.
All the chemical oxidation experiments
(as well as the UV oxidation
experiments) were performed in
duplicate. One control experiment was
performed for each set of duplicate
experiments. The control experiment
was performed under identical
conditions as the duplicated experiments
with the exception that no oxidant was
added. Therefore, the control
experiment established As(ni) losses
due to adsorption to the walls of the
reactor or other parts, and also
established any potential As(m) losses
due to reaction with the interfering
oxidants such as sulfide or dissolved
iron. During the course of this study,
several such control experiments were
performed and no As(m) losses were
observed as a result of arsenic
precipitation or adsorption.
Furthermore, all the oxidation data
indicated that when sulfide was present,
more rather than less As(IEI) passed
through the IX filter, which suggests that
sulfide did not precipitate and remove
As(m).
2.4.3.1 pH of Operation
For all of the oxidants studied, the extent
of As(DI) oxidation was determined for
a pH range of 6.3 - 8.3. The effect of
interfering reductants was only studied
at pH 8.3 because previous studies had
suggested that typical As-containing
groundwaters would have pH values of
8.3 ± 0.6 (Clifford and Lin, 1986, 1991;
Clifford, 1990; Clifford and Zhang,
1994; Clifford, et al, 1991, 1998a,
1998b; Ghurye, et al., 1998, 1999). This
may, however, not be true for all As-
containing waters.
2.4.3.2 High- andLow-DO Experiments
Chemical oxidation experiments, in
which the effect of dissolved iron on
As(in) oxidation was studied, had to be
performed in very low DO waters (< 0.1
mg/L DO) because dissolved iron
(Fe(E[)) is very easily oxidized in the
presence of DO at greater than neutral
pH values (Knocke et al. 1990).
Additionally, chemical oxidation
experiments with sulfide-spiked
synthetic water were also performed in
the absence of DO because sulfide can
be oxidized by DO. Dissolved oxygen
did not present a problem with the other
interfering reductants studied.
The high-DO chemical oxidation
experiments were performed by raising
the DO of the synthetic water to near-
saturation, by sparging with air (from the
lab air-distribution system) through a
diffuser for about 15 minutes. The
procedures used during these
experiments are described in Appendix
C. The low-DO chemical oxidation
experiments were performed by sparging
12
-------
extra dry grade nitrogen gas (containing
approx. 3 ppm ©2) through the synthetic
water to reduce the DO to < 0.1 mg/L as
measured by a lab DO meter. The
procedures used during the low-DO
experiments are described in detail in
Appendix C.
2.4.3.3 Oxidation Experiments with TOC
In order to determine the effect of TOC
on the oxidation of As(IH) with the five
chemical oxidants, untreated Lake
Houston water (not previously exposed
to oxidants) was filtered sequentially
through a 8.0, 0.45, and 0.22 urn filters
and then stored at 4 °C. Prior to an
experiment, the filtered Lake Houston
water was allowed to come to room
temperature (-24 °C). This was either
used directly by spiking with an
appropriate amount of As(IH) or diluted
with synthetic water to yield a water
with 2.1 mg/L TOC as in the ozone
experiments. The TOC in the filtered
Lake Houston water was not
characterized.
2.4.3.4 Low Temperature (5 °C)
Oxidation
A limited number of experiments were
performed at 5 °C to determine the effect
of low temperature on As(DI) oxidation.
Only those oxidants that were successful
in oxidizing As(ni) to As(V) were tested
at low temperature. The general
procedure for performing these
experiments was the same as the other
chemical oxidation experiments.
Additionally, the oxidation kinetics
reactor, filled with 500 mL of synthetic
water containing 50 [ag/L As(IE), was
refrigerated to a temperature of 5 ± 1 °C.
Upon attaining the required temperature,
the reactor was quickly removed from
the refrigerator and dosed with the
appropriate oxidant. The entire
experiment was usually completed in
less than 6 minutes from the time the
reactor was removed from the
refrigerator. At the end of the
experiment, the reactor water
temperature was usually in the range of
5-6 °C.
2.5 Solid-Phase Media (Filox)
Experiments
The solid-phase oxidizing media used in
this project was Filox-R™ (Matt-Son
Inc, Barrington, IL), which is typically
used for iron, hydrogen sulfide and
manganese- removal. The gray-black
granular Filox media (12 x 40 mesh,
bulk density 114 lbs/ft3) containing 75-
85% manganese dioxide, reportedly
utilizes an oxidation-reduction and
filtration process for removal of
dissolved iron, hydrogen sulfide and
manganese. In this study, the media was
used to oxidize As(m) to As(V) under a
variety of conditions.
2.5.1 Pretreatment of Filox Media
Approximately 100 mL of the Filox
media was backwashed with synthetic
water (of the composition in Table 1 and
without any As(DI)) in a 1 in.-i.d. glass
column at a flow rate of 285 mL/min (14
gal/min ft2) for 30 minutes. After
backwashing, 12 mL of media was
transferred to a 1 cm-i.d. glass column.
The bed depth was 6 inches (15 cm) and
the flow rate was varied from 16
mL/min (EBCT of 0.75 min) to 2
mL/min (EBCT of 6.0 min). A
schematic for the Filox experiments is
shown in Figure 2-4. All of the Filox
experiments were performed with the
same 12 mL of media, which was not
treated in any way except for periodic
backwashing.
13
-------
Synthetic
Test
Solution
1-cmi.d
Glass Column
-Filox Media
IX Speciating
Filter Holder
As(IE)
2-16 mL/min
Feed Reservoir
Figure 2-4. Schematic for Solid-Phase (Filox) Oxidizing Experiments.
2.5.2 Preparation of Low- and High-
DO Synthetic Water
The high-DO synthetic water (8.2 mg/L
DO) was prepared by sparging air
through synthetic water for about 15
minutes prior to passage through the
Filox column. The low-DO synthetic
water (0.1 mg/L DO) was prepared by
sparging extra-dry-grade nitrogen for 30
minutes through 500 mL of synthetic
water (or filtered Lake Houston water)
contained in the oxidation reactor.
2.5.3 Procedure for Variable-EBCT
and Variable-pH Experiments
The procedures for the variable-EBCT
and the variable-pH Filox experiments
were identical except for the pH of the
synthetic water. All of the variable-
EBCT experiments were performed at a
pH of 8.3 whereas during the variable-
pH experiments, the pH of the synthetic
water was varied at 6.3, 7.3, and 8.3.
The procedures are described in detail in
Appendix D.
2.5.4 Procedure to Stabilize Arsenic
Removal by Filox Media
During the variable-EBCT experiments,
it was observed that the Filox media, in
addition to oxidizing As(IEI) to As(V),
also removed arsenic. To enable the
media to come to equilibrium with the
As(IH)-containing water to better
represent what would occur in a Filox
column in actual field use, pre-
equilibration of the media was
attempted. To achieve equilibrium,
2000 BV (24 L) of pH 8.3 synthetic
water containing 50 |ag/L As(in) was
14
-------
passed through the media at an EBCT of
0.75 min.
2.5.5 Procedure for Low-DO Filox
Experiments
As mentioned earlier, the low-DO
synthetic water was prepared in the
oxidation reactor in the same manner as
during the chemical oxidation
experiments. The low-DO synthetic
water was then pumped directly from the
reactor to the Filox column. The
procedures used are described in detail
in Appendix D.
2.6 UV Oxidation Experiments
2.6.1 Unit 1: 0.5 gpm UV Sterilizer
Unit
A schematic for the UV oxidation
experiments is shown in Figure 2-5. The
experimental set-up for the UV
experiments was the same as for the
Filox experiments except that the Filox
column was substituted with a UV unit.
To Vacuum
IX Speciating
'Filter
Outlet
Vacuum Filtration
Apparatus
Inlet
Synthetic
Test
Solution
UV Apparatus
12-288 mL/min
Feed Reservoir
Figure 2-5. Schematic for UV-Oxidation Experiments.
Unit 1 was a 0.5 gpm unit from R-Can
Environmental Inc. (Canada), equipped
with a low-pressure mercury lamp with
an advertised lamp intensity of 32,000
uw/cm2 at 254 nm. The unit was
mounted vertically with the electrical
connections to the lamp on top to
prevent accidental water spillage from
damaging the sterilizer assembly. As
seen from Figure 2-5, the lower port was
chosen as the inlet and the upper port the
outlet. A 4-L HDPE container was filled
with synthetic water containing 50 |iig
As(III)/L. Before the UV lamp was
turned on, the synthetic test water was
pumped through the inactive sterilizer
assembly at 288 mL/min (residence time
1.0 min), and the effluent from the
15
-------
sterilizer unit was collected, speciated,
and analyzed for As(III). This served as
a control for the UV experiments to
ensure that the act of pumping the
synthetic water through the inactive
sterilizer unit did not cause any
inadvertent As(III) oxidation. The flow
was then switched to the lowest setting
corresponding to the highest residence
time employed. The lamp was switched
on and allowed to stabilize for 30
minutes, which is much longer than the
3-5 minutes recommended by the
manufacturer. At the end of 30 minutes,
three consecutive 50-mL samples were
collected, speciated, and analyzed as
As(III). The flow was then Increased to
the next flow rate and 600 mL (> two
times the void space of 288 mL in the
sterilizer assembly) of effluent was
wasted before three consecutive 50-mL
samples were collected, speciated and
analyzed for unoxidized As(III). The
above procedure was repeated until all of
the flow rates were studied. The
temperature of the water exiting the UV
unit was not measured.
2.6.2 Unit 2: 1.0 gpm UV Sterilizer
Unit
Unit 2 was a 1.0 gpm unit from Atlantic
Ultraviolet Corp., equipped with a low-
pressure mercury lamp with an
advertised lamp intensity of 41,200
uw/cm2 at 254 nm. The experimental
set-up and operation were similar to the
one used for Unit 1. The void space in
Unit 2 was larger, 486 mL, compared
with 288 mL for Unit 1.
2.7 QA/QC
2.7.1 Arsenic Standards
Four standards from an arsenic AAS
standard solution (Aldrich Chemical
Company, Inc.) containing 1000 jag
As/mL were employed for routine
arsenic analysis. The concentrations of
these "WAL standards" were 1.3, 2.8,
6.8, and 11.0 |4,g/L. Independently, the
QA/QC Officer for this project, prepared
four separate arsenic standards, which
served as internal QA/QC standards.
Two such sets of four QA/QC standards
were prepared by the QA/QC Officer
during the duration of this project. In
addition to the standards prepared at UH,
we utilized four previous "Water Supply
Laboratory Performance Evaluation
Study" standards. These standards were
preserved in a 0.2 M nitric acid solution.
These WS standards and their EPA-
reported true concentrations are as
follows:
Table 2-3. Previous EPA Standards.
Standard Year ' EPA-Reported
Concentration
Hg/L
WS037
WS038
WS040
WS041
1996
1997
1997
1998
49.3
83.1
102
65.6
16
-------
A stock solution containing 88.0 mg/L
As(III) was prepared according to the
procedure described in Appendix L.
2.7.2 Routine Arsenic Analysis
Routine arsenic analyses were performed
by the WAL during the course of this
project. Each batch of samples was
analyzed according to the following
sequence:
(1) A prep blank (prepared the same as a
routine sample with the exception that
reagent grade water was substituted for
the arsenic sample) was analyzed
followed by the four WAL standards.
Then, one of the four QA/QC standards
was analyzed. This sequence is hereafter
referred to as a "set of standards."
(2) Following measurement of the set of
standards, no more than 20 samples were
analyzed. This was followed by the
analysis of the set of standards. Once
again, no more than 20 samples were
analyzed followed by the set of
standards, and so on until all of the
samples had been analyzed.
(3) Then each of the four WS standards
was measured. Each of the WS
standards was spiked with 2.0 ug/L
arsenic and measured to calculate spike
recoveries.
(4) Finally, the set of standards was
measured to complete the analyses.
2.7.3 Arsenic Calibration Curve
A calibration curve was developed for
arsenic based on the prep blank and the
four WAL standards. The QA/QC
standard was thus excluded from the
points contributing to the calibration
curve and its concentration was
calculated on the basis of the calibration
curve. Figure 2-6 shows a typical
calibration curve with the QA/QC
standard included for comparison. In
Figure 2-6, each standard was measured
eight times. The concentration of the
QA/QC standard in Figure 2-6 was 5.97
ug/L and the average of eight
measurements of the QA/QC standard
was 5.91 ug/L.
17
-------
0.8
0.6
a
a
0.4
0.2
Absorbance (WAL Standards)
Absorbance (5.97 og/L QA/QC Standard)
Equation for Arsenic Calibration Curve
y = 0.0048851 + 0.058708x R= 0.99985
2 4 6 8
Arsenic Concentration (ug/L)
Figure 2-6. Typical Arsenic Calibration Curve.
10
12
2.8 Analytical Methods
Table 2-4 shows the various analytical
methods used during the course of this
project. Only chlorine dioxide was
analyzed by multiple methods for the
reasons mentioned in the Results and
Discussion section of this report.
Table 2-4. Analytical Methods
Total Arsenic
Chlorine, nitrate, sulfate
Total Organic Carbon
Sulfide
FeandMn
Chlorine (hypochlorite)
Chlorine Dioxide
Ozone
Permanganate
Monochloramine
SM 3114 A (Hydride Generation)
SM 4110 B (Ion Chromatography)
SM 5310 B (Combustion-Infrared)
Hach Manual. EPA-approved and adapted from
SM 4500-S2' E (Colorimetric)
SM 3111 B (Atomic Absorption)
Potentiometric Method of Knocke, et al. (1990)
Potentiometric Method of Knocke, et al. (1990)
SM 4500-C1O2- D (DPD Method)
Hach Method 8138 (Direct UV absorbance @445
nm)
Hach Method 8311 (Colorimetric)
Potentiometric Method of Knocke, et al. (1990)
SM 4500-C1 G (DPD Method)
18
-------
3. Results and Discussion
3.1 Reactor Set-up Test
Results
3.1.1 Arsenic(V) Retention
The IX filter was challenged with
synthetic water (composition shown in
Table 1) containing As(V)
concentrations of 50 and 1000 \ig/L.
The results are shown in Figures 3-1 and
3-2. It can been seen that for the first
100 mL passing through the filter,
greater than 98% As(V) retention was
obtained with 50 ug/L solution and
greater than 95% for the 1000 jag/L
solution. For both As(V) concentrations,
at least 100 mL of synthetic water could
be put through the IX filter (@ 20
mL/min) before arsenic leakage
exceeded 5%.
Fresh IX Filter
First Regeneration
—V— Second Regeneration
Third Regeneration
Fourth Regeneration
Fifth Regeneration
As(V) = 50 ug/L
Sulfate = 24 mg/L
TDS = 351mg/L
95% As(V) Retention
98% Retention
50 100 150 200
mL passed through IX Filter @ 20 mL/min
Figure 3-1. 50 |ig/L-As(V) Retention by IX Filter.
250
19
-------
i
I
1
800
600
400 -
u
a 200
5
0
Fresh IX Filter
First Regeneration
Second Regeneration
Third Regeneration
Fourth Regeneration
Fifth Regeneration
As(V) = 1000 ug/L
Sulfate = 24mg/L
TDS = 351mg/L
95% As(V) Retention
0
50 100 150
mL passed through IX Filter @ 20 mL/min
Figure 3-2. 1000 ug/L-As(V) Retention by IX Filter.
200
250
5.1.2 Arsenic(III) Recovery
It was also necessary to demonstrate that
the unoxidized As(III) that passed from
the oxidation reactor through the
speciation media was not adsorbed or
oxidized by the speciation media.
Figures 3-3 and 3-4 show the As(III)
recoveries with initial arsenic
concentrations of 50 and 1000 jag/L. No
significant As(III) oxidation resulted
from use of the IX filter, and As(III)
recovery averaged 95-105% for the 50
fig As(III)/L-spiked water and 90-110%
for the 1000 |J.g As(III)/L-spiked water.
20
-------
§
a
u
60
50
40
30
20
10
0
Fresh IX Filter
First Regeneration
Second Regeneration
Third Regeneration
Fourth Regeneration
100% As(III) Recovery
As(m) = 50 jig/L
Sulfate = 24 mg/L
TDS = 351 mg/L
0 50 100 150
mL passed through IX Filter @ 20 mL/min
Figure 3-3. 50 |j.g/L-As(III) Recovery from IX Filter.
200
^•^
ncentration (fi
Arsenic Cc
1200
1000
son
600
400
200
1
(
; -^--i^^-^^ :
- ^4*^^_V^C^?S=ri^^^^ 100% As(HI) Recovery
—e— Fresh IX Filter
— 0 — First Regeneration As(m) = 1000 fig/L |
— V — Second Regeneration Sulfate = 24 mg/L
— B — Third Regeneration TDS = 351 mg/L
— >? — Fourth Regeneration '
. , , , i , , . , i . . . i i i 1 i 1
) 50 100 ISO 20
mL passed through IX Filter @ 20 mL/min
Figure 3-4. 1000 ng/L-As(III) Recovery from IX Filter.
3.1.3 Dead Volume in the Oxidation
Reactor Set-up
The results of the dead-volume
experiment are presented in Figure 3-5,
which shows the volume of system
effluent that must pass through the IX
filter before the actual reactor effluent is
sampled. The response was 50 and 80%
after 2 and 4 mL of flow, respectively.
The true dead volume is probably closer
21
-------
to 2 mL, the point at which 50% of the
response is achieved. However, due to
the presence of water in the dead space
above the IX filter hi addition to water
within the filter itself, and the inevitable
mixing (and dilution) that results
between the incoming flow from the
reactor and the water in the dead space,
it took 4 mL of flow for the response to
reach 80% and nearly 8 mL to reach
100%.
£
1
S
o
y
u
§
!2
1200
1000
800
600
400
200
100 % Resppnse_
1st Run
2nd Run
3rd Run
Synthetic Test Water
At t=0, inject As(III) = 1000 ug/L
246
mL passed through IX Filter @ 5 mL/min
Figure 3-5. Estimation of dead volume in the reactor set-up.
A certain initial volume of effluent from
the reactor had to be wasted to
compensate for the dead volume hi the
system, after which the actual contents
of the reactor could be sampled.
Therefore, if the dead volume was not
wasted, then the first few samples would
be substantially diluted by the fluid hi
the dead volume. Also note that during
actual oxidation experiments, when fluid
exits the reactor, the oxidation reaction
continues because the oxidant is still hi
contact with As(III). Therefore, the time
spent to waste the dead volume must be
taken into account.
Based on Figure 3-5, it was decided that
four mL (corresponding to >80%
response) of the reactor effluent would
have to be wasted before the actual
reactor contents could be sampled.
Thus, for a sampling flow rate of 20
mL/min during actual oxidation
experiments, the first sample that
represented the dead volume (4 mL) was
collected during the 0-12 second
interval. The next sampling interval was
12-18 sec (median time 15 sec).
Consequently, no reaction time earlier
than 15 sec could be studied.
3.1.4 Mixing Efficiency in Oxidation
Reactor
The results of this experiment showed
that the effluent arsenic concentrations
(representing unoxidized As(III)) were
22
-------
usually lower than 0.4 ug/L (Figure 3-6).
The low effluent As(III) concentrations
confirmed the rapidity of As(III)
oxidation by chlorine as previously
reported by Frank and Clifford (1986)
and also showed the efficiency of mixing
in the reactor. If the reactor had
provided inadequate mixing, the initial
effluent As(III) concentrations (for t =
15 seconds) would have been much
higher than was actually observed.
10
r
First Run
• Second Run
• Third Run
Synthetic Test Water
Initial As(ffl) = 10 ug/L
At t=0, inject «2 = 2 mg/L
Flow Rate=20 mL/min
4 mL wasted as dead volume
Effluent collected at 6 sec (2 mL) intervals)
Time elapsed after oxidant addition (seconds)
Figure 3-6. Mixing efficiency in oxidation reactor.
3.2 Chlorine Test Results
The results of the chlorine oxidation
experiments are summarized in Table 3-
1 and discussed below.
3.2.1 Effect ofpH on Chlorine
Chlorine rapidly oxidized As(III) in the
pH range of 6.3-8.3 (Table 3-1,
experiments 1-3 and Figure 3-7).
Oxidation was slightly slower at pH 6.3
but still complete in 39 seconds. Higher
As(III) concentrations were also
completely and rapidly oxidized by
chlorine (Table 3-1, experiment 11).
The time reported (in Table 3-1 and
similar Tables elsewhere) to >95%
oxidation was the median time of its
sample interval, i.e., if greater than 95%
oxidation was observed in the earliest
sampling interval, 12-18 sec, then the
time was reported as 15 seconds.
23
-------
Table 3-1. Free Chlorine Experiments.
#
1
2
3
4
5
6
7
8
9
10
11
As(III)
Cone
50
50
50
50
50
50
50
50
50
50
1000
Chlorine
Cone1
(mg/L)
0.14
0.14
0.14
0.48
0.48
0.48
0.48
0.48
0.48
0.14
2.84
SR2
Cl2/As
3
3
3
10
10
10
10
10
10
3
3
SR3
cy
(As+IR)
NA
NA
NA
1.55
0.27
1.20
0.215
O.ll5
NA
NA
NA
pH
8.3
7.3
6.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
Interfering
Reductant
(IR)
None
None
None
Fe (II) (0.3 mg/L)
Fe (II) (2.0 mg/L)
Mn (II) (0.2 mg/L)
S2' (1.0 mg/L)
S2' (2.0 mg/L)
TOC (6.9 mg/L)
Temperature (5 °C)
None
>95%
Oxid4
(sec)
15
15
39
15
15
27
57
57
15
15
15
1—Oxidant dosed as NaOCl, reported as mg/L chlorine
2—Stoichiometric Ratio of Oxidant/As(III)
3—Stoichiometric Ratio of Oxidant/(As(III) + Interfering Reductant)
4—Average of duplicate runs
5—Based on oxidation of sulfide to elemental sulfur
50
pH8.3
pH8.3
pH7.3
pH7.3
pH6.3
pH6.3
As(ni) = 50 jig/L
C12 = 0.14 mg/L (3 x As(ffl) Stoichiometric)
100
150
200
250
300
350
Time (seconds)
Figure 3-7. Effect of pH on As(III) Oxidation with Free Chlorine.
24
-------
5.2.2 Effect of Dissolved Manganese
andiron on Chlorine
The results of the dissolved manganese
and iron experiments at pH 8.3 are
shown in Table 3-1, experiments 4, 5
and 6. Only a slight effect of dissolved
manganese was observed on As(III)
oxidation where complete oxidation was
observed in 27 seconds with Mn(II)
present compared with 15 seconds in the
absence of Mn(II). Dissolved iron had
no effect on As(III) oxidation at pH 8.3.
3.2.5 Effect ofSulfide on Chlorine
The results of the sulfide experiments
are shown in Table 3-1, experiments 7
and 8. Although sulfide (1.0 and 2.0
mg/L) slowed the oxidation reaction,
complete oxidation was still obtained in
less than 1 min (Figure 3-8). However,
higher sulfide concentrations may
further slow As(III) oxidation so that
reaction tunes much greater than 1 mm
or higher oxidant doses become
necessary to achieve complete As(III)
oxidation.
• pH 8.3; No Sulfide
• pH 8.3; No Sulfide
• Sulfide = 1.0 mg/L
• Sulfide = 1.0 mg/L
• Sulfide = 2.0 mg/L
• Sulfide = 2.0 mg/L
As(HI) = 50 jigfL
Sulfide = 1.0 and 2.0 mg/L
CI = 0.48 mg/L (10 x As (DO) Stoichiometric)
=*=
100
150
200
250
300
350
Time (seconds)
Figure 3-8. Effect of sulfide on As(HI) oxidation with free chlorine.
3.2.4 Effect of TOC and Temperature
on Chlorine
The results of the TOC and temperature
experiments are shown in Table 3-1;
experiments 9 and 10. Neither the
presence of 6.9 mg/L TOC in Lake
Houston water nor a low temperature of
5 °C had any significant effect on As(III)
oxidation because the time required for
complete oxidation for both conditions
was the same as that required when no
interfering reductants were present.
3.3 Permanganate Test
Results
Eleven experiments were conducted
using permanganate as an oxidant, and a
25
-------
summary of the results is shown in Table
3-2
3.5.1 Effect ofpH on Permanganate
Permanganate rapidly oxidized As(III) in
the pH range of 6.3-8.3 (Table 3-2,
experiments 1-3 and Figure 3-9).
Oxidation was slightly slower at pH 6.3
but still complete in 33 seconds. Higher
As(III) concentrations were also
completely and rapidly oxidized by
permanganate (Table 3-2, experiment
11).
Table 3-2. Permanganate Experiments.
#
1
2
3
4
5
6
7
8
9
10
11
As(III)
Cone
50
50
50
50
50
50
50
50
50
50
1000
Mn04-
Conc
(mg/L)
0.16
0.16
0.16
0.53
0.53
0.53
0.53
0.53
0.53
0.16
3.20
SR1
MnO4V
As
3
3
3
10
10
10
10
10
10
3
3
SR2
MnO47
(As+IR)
NA
NA
NA
1.99
0.36
1.55
0.214
O.ll4
NA
NA
NA
pH
8.3
7.3
6.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
Interfering
Reductant
(IR)
None
None
None
Fe (II) (0.3 mg/L)
Fe (II) (2.0 mg/L)
Mn (II) (0.2 mg/L)
S2' (1.0 mg/L)
S2' (2.0 mg/L)
TOC (6.9 mg/L)
Temperature (5 °C)
None
>95%
Oxid3
(sec)
15
15
33
21
15
21
51
51
15
15
15
1—Stoichiometric Ratio of Oxidant/As(III)
2—Stoichiometric Ratio of Oxidant/(As(III) + Interfering Reductant)
3—Average of duplicate runs
4—Based on oxidation of sulfide to elemental sulfur
26
-------
§
pH8.3
pH8.3
pH7.3
pH7.3
pH6.3
pH6.3
150
200
250
300
350
Time (seconds)
Figure 3-9. Effect of pH on As(III) oxidation with permanganate.
3.3.2 Effect of Dissolved Manganese
andiron on Permanganate
The results of the dissolved manganese
and iron experiments are shown in Table
3-2, experiments 4, 5 and 6. Neither
dissolved manganese nor dissolved iron
(Fe(II)) had any significant effect on
As(III) oxidation at pH 8.3 with
complete oxidation achieved in 21
seconds or less.
3.3.3 Effect of Sulflde on
Permanganate
The results of the sulfide experiments
are shown in Table 3-2, experiments 7
and 8. Although sulfide (1.0 and 2.0
mg/L) slowed the oxidation reaction,
complete oxidation was still obtained in
less than 1 min (Figure 3-10). However,
higher sulfide concentrations may
further slow As(III) oxidation such that
reaction times much greater than 1 min
and/or higher oxidant doses will be
required to achieve complete oxidation.
27
-------
50
40
30
20 -]
! 10
As(ffl) = 50 ug/L
Sulfide = 1.0 and 2.0 mg/L
pH 8.3; No Sulfide
pH 8.3; No Sulfide
Sulfide = 1.0 mg/L
Sulfide = 1.0 mg/L
Sulfide = 2.0 mg/L
Sulfide = 2.0 mg/L
MnO4' = 0.53 mg/L (10 x As(III) Stoichiometric)
50
100
150
200
250
300
350
Time (seconds)
Figure 3-10. Effect of sulfide on As(III) oxidation with permanganate.
3.3.4 Effect of TOC and Temperature
on Permanganate
The results of the TOC and temperature
experiments are shown in Table 3-2,
experiments 9 and 10. Neither the
presence of TOC nor a low temperature
of 5 °C had any significant effect on
As(Tfl) oxidation by permanganate.
Complete oxidation was achieved for
both the conditions in 15 seconds.
3.4 Ozone Test Results
Eleven experiments were conducted
using ozone as an oxidant, and a
summary of the results is shown in Table
3-3.
28
-------
Table 3-3. Ozone Experiments.
#
1
2
3
4
5
6
7
8
9
10
11
Cone
50
50
50
50
50
50
50
50
50
50
50
Ozone
Cone
(mg/L)
0.10
0.10
0.10
0.32
0.32
0.32
0.32
0.32
0.32
0.32
0.10
SR1
3
3
3
10
10
10
10
10
10
10
3
SR2
95%
Oxid3
(sec)
15
15
15
15
15
15
51
132
27
NA5
39
1—Stoichiometric Ratio of Oxidant/As(III)
2—Stoichiometric Ratio of Oxidant/(As(III) + Interfering Reductant)
3—Average of duplicate runs
A—Based on oxidation of sulfide to elemental sulfur
5—Max. oxidation achieved with 6.9 mg/L TOC was 38%
3.4.1 Effect ofpH on Ozone
In the range of 6.3-8.3, pH had no effect
on As(III) oxidation with complete
oxidation achieved in 15 seconds as seen
in Table 3-3, experiments 1-3 and Figure
3-11.
pH8.3
pH8.3
pH7.3
pH7.3
pH6.3
pH6.3
As(ffl) = 50
O3 = 0.1 mg/L (3 x As(III) Stoichiometric)
100 150 200
Time (seconds)
Figure 3-11. Effect of pH on As(III) oxidation with ozone.
250
300
350
29
-------
3.4.2 Effect of Dissolved Manganese
andiron on Ozone
The results of the dissolved manganese
and iron experiments are shown in Table
3-3, experiments 4, 5 and 6. Neither
dissolved Mn (0.2 mg/L) nor dissolved
Fe (0.3 and 2.0 mg/L) had any effect on
As(III) oxidation by ozone at pH 8.3,
with complete As(III) oxidation being
achieved in 15 seconds.
3.4.3 Effect ofSulfide on Ozone
The results of the sulfide experiments
are shown in Table 3-3, experiments 7
and 8. The presence of sulfide at 1.0
and 2.0 mg/L slowed As(III) oxidation
by ozone at pH 8.3. At sulfide
concentrations of 1.0 and 2.0 mg/L,
greater than 95% oxidation was achieved
in 51 and 132 seconds, respectively
(Figure 3-12). By comparison, in the
absence of sulfide, >95% oxidation was
achieved in just 15 seconds and at a
much lower ozone dose of three-times
the stoichiometric requirement. Note,
however, that in the presence of 1.0 and
2.0 mg/L sulfide (SR = 0.21 and 0.11,
respectively), there was insufficient
ozone to oxidize both As(III) and
sulfide.
pH 8.3; No Sulfide
H 8.3; No Sulfide
ulfide = 1.0 mg/L
Sulfide = 1.0 mg/L
Sulfide = 2.0 mg/L
Sulfide = 2.0 mg/L
As(ffl) = 50 ug/L, pH = 8.3
Sulfide = 1.0 and 2.0 mg/L
O = 0.32 mg/L (10 x As(IH) Stoichiometric)
100
150
200
250
300
350
Time (seconds)
Figure 3-12. Effect of sulfide on As(III) oxidation with ozone.
3.4.4 Effect of TOC and Temperature
on Ozone
The results of the TOC and temperature
experiments are shown in Table 3-3,
experiments 9 and 10. The presence of
TOC had a significant quenching effect
on the ability of ozone to oxidize As(III)
in filtered Lake Houston water (Figure
3-13). With 6.9 mg/L TOC, there was
insufficient ozone present to oxidize
both As(III) and the TOC. Since most
arsenic-contaminated groundwaters are
30
-------
unlikely to contain such high TOC, the
Lake Houston water was diluted with
synthetic water (composition shown in
Table 2-1) to yield a TOC of about 2.1
mg/L. In the presence of this lower TOC
concentration, ozone was able to
efficiently oxidize As(III), with greater
than 95% oxidation achieved in 27
seconds.
Initial As(III) = 50 pg/L
pH = 8.3
O, = 0.32 mg/L (10 x As(ni) Stoichiometric)
3
TOC = 6.9 mg/L
TOC = 6.9 mg/L
TOC = 6.9 mg/L
TOC = 2.1 mg/L
TOC = 2.1 mg/L
TOC = 2.1 mg/L
TOC = 2.1 mg/L
200
250
300
350
Time (seconds)
Figure 3-13. Effect of TOC on As(III) oxidation with ozone.
3.5 Chlorine Dioxide Test
Results
Thirteen arsenic oxidation experiments
with chlorine dioxide were performed
assuming a conservative one-electron
transfer mechanism, i.e., chlorine
dioxide is converted to C1O2" while
oxidizing As(III) to As(V). The five-
electron transfer mechanism was only
used in calculating chlorine dioxide
doses for the Fe(H)-oxidation
experiments (Knocke, et al., 1990). The
results of the thirteen tests are
summarized in Table 3-4.
3.5.1 Effect of pH on Chlorine
Dioxide
In the pH range of 6.3-8.3, chlorine
dioxide produced limited oxidation (20-
30%) in 21 seconds and produced no
further oxidation (Table 3-4,
experiments 1, 2, 3 and 9). In order to
verify that the IX filter was undamaged
by chlorine dioxide and functioning
normally, two more experiments were
performed, which included a three-times
Stoichiometric amount of chlorine
injected at 117 seconds. If filter
integrity was maintained, the unoxidized
As(HI) concentration would be hi the
range of 35-40 ug/L after chlorine
dioxide addition, and then quickly drop
to zero due to complete As(III) oxidation
31
-------
range of 35-40 |J.g/L after chlorine
dioxide addition, and then quickly drop
to zero due to complete As(in) oxidation
after the addition of chlorine. The
results of these experiments are shown in
Figure 3-14, which shows that only 20-
30% oxidation was obtained with
chlorine dioxide, but complete oxidation
was achieved after the addition of
chlorine. This test confirmed that the IX
filter, which separates As(ni) from
As(V), was still effective after exposure
to chlorine dioxide.
Table 3-4. Chlorine Dioxide Experiments.
# As(m) C1O2 Cone
Cone (|ag/L) (mg/L)
1
2
3
4
5
6
7
8
9
10
11
12
13
50
50
50
50
50
50
0
0
505
50
50
50
50
0.27
0.27
0.27
0.90
0.90
0.90
1.08
1.08
0.27
C1O2=0.27
C12=0.14
0.27
0.90
9.00
SR1 SR2
cio2/As cicy
(As+m.)
3
3
3
10
10
10
NA
NA
3
3
3
3
10
100
NA
NA
NA
5.56
1.58
1.12
1.12
NA
NA
NA
NA
NA
pH
8.3.,
7.3
6.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
Interfering
Reductant
OR)
None
None
None
Fe (H) (0.3 mg/L)
Fe (H) (2.0 mg/L)
Mn (H) (0.2 mg/L)
Fe(H) (4.0 mg/L)4
Without silica
Fe(D[) (4.0 mg/L)4
None
None
Deaerated
synthetic water
None
None
>95%
Oxid3
(sec)
>323
>312
>312
>312
>312
>312
15
15
>312
>NA6
>312
>312
>312
1—Stoichiometric Ratio of Oxidant/As(III)
2—Stoichiometric Ratio of Oxidant/(As(III) + Interfering Reductant) based on a 1-electron transfer
mechanism, except for Fe(II) which is oxidized by chlorine dioxide by a 5-electron transfer mechanism
3—Average of duplicate runs
4—Experiments 7 and 8 were performed to duplicate the Fe(II) oxidation experiments of Knocke (1990).
Silica was eliminated from #7 as it is known to complex Fe.
5—Repeat of experiment # 1
6—Complete Oxidation was achieved only after the addition of chlorine
32
-------
50
a
20
10
0
As(UT) = 50 ug/L, pH = 8.3
CIO2 = 0.27 mg/L (3 x As(m) Stoichiometric)
Cl = 0.14 mg/L (3 x) injected at t
117 sec
1A-CIO2 only
1B-C1O2 only
2A-C1O2 only
2B-C1O2 only
3A-C1O2, then
3B-CIO2, then
0
50
100
250
300
350
150 200
Time (seconds)
Figure 3-14. Arsenic(III) oxidation with chlorine dioxide. Chlorine injected at 117 sec to
verify IX filter performance in experiments 3A and 3B.
The ineffectiveness of chlorine dioxide
was surprising as it is known to be a
powerful oxidant. Moreover, the
phenomenon of 20-30% oxidation in 21
seconds with no further oxidation could
not be explained. The scope of research,
the budget, and time constraints
preempted further investigation into the
reasons for this ineffectiveness.
Possibly, the initial As(III) oxidation
seen in the chlorine dioxide experiments
was due to the presence of chlorine in
the chlorine dioxide stock solutions.
Knocke et al. (1990) reported the
formation of about 20 mg/L HOC1 (27
mg/L as chlorine) along with 750 mg/L
C1O2 (390 mg/L as chlorine). It is
possible that the rapid initial As(III)
oxidation observed in these experiments
was the result of the presence of a very
small fraction of chlorine in the C1O2
stock solutions, and was not due to
chlorine dioxide itself. It should also be
noted that this fraction of chlorine
probably varied from one batch to
another. Therefore, an increase in the
concentration of chlorine dioxide dose
does not necessarily imply a
proportionate increase in the chlorine
fraction as well.
3.5.2 Verifying Chlorine Dioxide
Stock Concentrations.
In order to verify the ineffectiveness of
chlorine dioxide and rule out
measurement errors, the chlorine dioxide
stock solution was assayed to ensure that
the proper oxidant dose was delivered.
Three different methods were used: (1)
Potentiometric method from Knocke et
al. (1990), (2) Standard Method 4500-
C1O2-D (DPD Method), and (3) Hach
Method 8138, a direct-reading method
with a range of 0-700 mg/L. Both the
Potentiometric and DPD methods gave
excellent agreement while the Hach
method underestimated the chlorine
33
-------
dioxide concentration by about 6%. The
results are shown in Table 3-5.
Table 3-5. Chlorine Dioxide Assays.
Method
SM4500-C1O2-D
Potentiometric
Hach8318
Observed
Value (mg/L)
458
453
430
Difference1
%
-
-1.1
-6.1
1—Difference from value obtained using the Standard Method assay.
3.5.3 Fe(II) Oxidation with Chlorine
Dioxide
Knocke et al. (1990) reported essentially
instantaneous oxidation of Fe(II) to
Fe(III) by chlorine dioxide at a dose of
105% of stoichiometric requirement.
These experiments were repeated for an
initial Fe(II) concentration of 4 mg/L.
The results of these experiments are
shown in Table 3-4, experiments 7 and
8. With a chlorine dioxide dose of 1.08
mg/L (1.12 tunes stoichiometric), an
initial Fe(II) concentration of 4 mg/L
was completely oxidized in 15 seconds.
To eliminate dissolved oxygen as a
potential cause for the ineffectiveness of
chlorine dioxide for As(III) oxidation,
tests were performed in low-DO (0.1
mg/L) synthetic water. The absence of
DO did not improve the performance of
chlorine dioxide for As(III) oxidation.
3.5.4 Increasing Stoichiometric Dose
of Chlorine Dioxide
The chlorine dioxide dose was increased
to ten- and one-hundred-times the
stoichiometric amount required for
As(III) oxidation. These results are
shown in Table 3-4, experiments 12 and
13. Even at a chlorine dioxide dose of
9.0 mg/L (100 x stoichiometric), only
about 76% As(III) oxidation was
observed at the end of 5 minutes.
3.5.5 Effect of Dissolved Manganese
andiron on Chlorine Dioxide
The results of the dissolved manganese
and iron experiments are shown in Table
3-4, experiments 4, 5 and 6. The
presence of dissolved manganese and
iron in the synthetic water resulted in
somewhat lower As(III) concentration in
the reactor effluent compared with
synthetic water without interfering
reductants present. The lower residual
As(III) concentrations observed were
due to adsorption of As(III) and As(V)
onto the manganese and iron hydroxide
precipitates that formed upon chlorine
dioxide addition.
3.5.6 Effect of Sulflde, TOC and
Temperature on Chlorine Dioxide
Because of the ineffectiveness of
chlorine dioxide as an oxidant in the
absence of interfering reductants, As(III)
these experiments were deemed
unnecessary.
34
-------
3.6 Monochloramine
Results
Test F°ur experiments were performed with
monochloramine as oxidant. The results
are summarized in Table 3-6.
Table 3-6. Monochloramine Experiments.
#
1
2
3
4
AsCffl)
Cone
(l^g/L)
50
50
50
50
NH2C1
Cone
(mg/L)
0.10
0.10
0.10
0.104
SR1
NH2C1/
As
3
3
3
3
SR2
NH2C]7
(As+IR)
NA
NA
NA
NA
pH
8.3
7.3
6.3
8.3
Interfering
Reductant
(IR)
None
None
None
None
>95%
Oxid3
(sec)
>312
>312
>312
>312
1—Stoichiometric Ratio of Oxidant/As(III)
2—Stoichiometric Ratio of Oxidant/(As(III) + Interfering Reductant)
3—Average of duplicate runs
4—With preformed monochloramine
3.6.1 Effect of pH on
Monochloramine
In the pH range of 6.3-8.3, limited
oxidation (40%) was produced by in-
szYw-formed monochloramine in the first
21 seconds with no oxidation observed
thereafter.
•i
•s
1
8
50
40
30
20
10
0
As(III)=50ng/L
NILCI = 0.1 mg/L (3 x As Stoichiometric)
pH 8.3; in-situ-formed Monochloramine
pH 8.3; in-situ-formed Monochloramine
pH 7.3; in-situ-formed Monochloramine
pH 7.3; in-situ-formed Monochloramine
pH 6.3; in-situ-formed Monochloramine
pH 6.3; in-situ-formed Monochloramine
pH 8.3; preformed Monochloramine
pH 8.3; preformed Monochloramine
0
50
100
150
200
Time (seconds)
Figure 3-15. Arsenic(m) oxidation with monochloramine.
250
300
350
35
-------
These results are in agreement with the
findings of Frank and Clifford (1986)
who speculated that the occurrence of
rapid initial As(III) oxidation was due to
free chlorine before it reacted with
ammonia to form monochloramine. To
test this hypothesis, a 10 mg/L
monochloramine solution was prepared,
assayed, and used as a stock solution.
When preformed monochloramuie was
added to the reactor, no As(III) oxidation
was observed (Figure 3-15). Because a
three-times-stoichiometric amount of
monochloramine failed to produce any
As(III) oxidation, it was not studied
further.
3.7 Solid-Phase Oxidizing
Media (Filox)
Twenty-four experiments were
conducted with the Filox media and the
test results are summarized in Table 3-7.
The variables studied for their effect on
As(III) oxidation included EBCT, pH,
DO, dissolved Mn, dissolved Fe, sulfide,
TOC and initial As(III) concentration.
All of the Filox experiments described in
this report were performed with the same
12 mL of Filox Media. The media was
backwashed after each experiment, but
was otherwise untreated.
3.7.1 Filox: Effect of Empty Bed
Contact Time with High-DO
The effect of EBCT, from 0.75 to 6 min,
on As(III) oxidation is shown in Figure
3-16 and Table 3-7, experiments 1-4.
Even at the shortest EBCT of 0.75 min,
greater than 95% As(III) oxidation was
obtained. The media also removed
arsenic, in addition to oxidizing it, as
seen in Figure 3-16. Arsenic removal
increased from 45 to 64% as the EBCT
increased from 0.75 to 6.0 min.
36
-------
Table 3-7. Filox Experiments.
#
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
As(III)
Hg/L
Interfering
Reductant
(IR, mg/L)
pH
DO1
(mg/L)
EBCT2
(min)
% As(III)
Oxidation
%As
Removal
Variable EBCT
50
50
50
50
None
None
None
None
8.3
8.3
8.3
8.3
8.2
8.2
8.2
8.2
0.75
1.5
3.0
6.0
95.4
98.7
98.7
99.4
45.3
48.2
55.0
63.6
Variable pH
50
50
None
None
7.3
6.3
8.2
8.2
1.5
1.5
99.8
100.0
66.2
75.3
Interfering Reductants, Low-DO, Low EBCT
50
50
50
50
50
50
50
50
None
Mn(II)— 0.2
Fe(II)— 0.3
Fe(II)— 2.0
Sulfide— 1.0
Sulfide— 2.0
TOC— 1.4
None/8 °C
8.3
8.3
8.3
8.3
8.3
8.3
8.3
8.3
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
98.9
78.2
80.9
81.3
61.5
55.7
79.2
98.3
36.1
12.4
19.1
13.9
5.0
9.4
7.2
36.5
Interfering Reductants, Low-DO, High EBCT
50
50
50
50
Mn(II)— 0.2
Sulfide— 1.0
Sulfide— 2.0
TOC— 1.4
8.3
8.3
8.3
8.3
0.1
0.1
0.1
0.1
6.0
6.0
6.0
6.0
99.8
99.6
97.0
99.9
51.1
57.4
42.4
47.5
19
20
High Initial Arsenic(III) Concentration
1000 I None I 8.3 I 0.1
1000 I None | 8.3 | 8.2
Interfering Reductants, High-DO, Low EBCT
1.5
1.5
96.7
95.0
1—High DO = 8.2 mg/L; Low DO = 0.1 mg/L
2—EBCT of 0.75, 1.5, 3.0 and 6.0 equal 4.9,2.5,1.2 and 0.6 gpm/ft2, respectively.
44.8
50.3
21
22
23
24
50
50
50
50
Mn(II)— 0.2
Sulfide— 1.0
Sulfide— 2.0
TOC— 1.4
8.3
8.3
8.3
8.3
8.2
8.2
8.2
8.2
1.5
1.5
1.5
1.5
98.4
98.3
96.2
97.5
50.8
76.1
77.1
55.4
37
-------
I
3
a
•2
£
a
I
1
50
40
30
20
10
• As(III) Remaining I
• Total Effluent As |
Initial As(III) = 50
pH = 8.3
DO = 8.2 mg/L
Line of 90% Arsenic(III) Oxidation
0
1.5 3
Empty Bed Contact Time (min)
Figure 3-16. Effect of EBCT on Filox Media.
4.5
In an effort to stabilize arsenic
adsorption, attempts were made to
equilibrate the Filox media with As(III)-
spiked synthetic water before any further
experiments were performed. Hence,
2000 BV (24 L) of 50 ug/L As(III)-
spiked synthetic water was passed
through the Filox media at a flow rate of
16 mL/min corresponding to an EBCT
of 0.75 min and a total equilibration time
of 25 hours of interrupted flow over a
three-day period. The results are shown
in Figure 3-17. Arsenic oxidation rate
started out at 96% (2 ug/L As(III)
remaining) and decreased slightly to
93% (4 ug/L As(III) remaining) at 2000
BV. Arsenic removal by the Filox
media decreased significantly as the run
progressed. From an initial removal rate
of 26%, arsenic removal decreased to
8% at 2000 BV, indicating that the
media's capacity for arsenic adsorption
was nearly exhausted. Figure 3-17 also
shows that the Filox media will initially
oxidize As(III) and remove it, but will
eventually come to equilibrium with the
influent arsenic and provide no further
arsenic removal while still oxidizing
As(III) to As(V). It should also be noted
that no arsenic was dumped from the
Filox media in the equilibration
experiment or in any subsequent
experiments.
38
-------
I
50
40
30
a 20
S 10
0
• Toi
O Asi
uent As
.emaming
Initial As(III) = 50 fig/L
pH = 8.3
DO = 8.2 mg/L
Line of 90% Arsenic(III) Oxidation
O o
o°o0ooooo0oo0o°°o!>
0
500
1500
2000
1000
Bed Volumes
Figure 3-17. Filox media equilibration with 2000 BV of synthetic test water at an EBCT
of 0.75 min.
3.7.2 Filox: Effect of pH with High-
DO
The results on the pH tests in the range
of 6.3-8.3 showed that pH had no
significant effect on arsenic oxidation by
the Filox media (Figure 3-18). Greater
than 98% As(III) oxidation was achieved
in the pH range of 6.3-8.3. Total arsenic
(As(III) + As(V)) removal, however,
increased with decreasing pH, with
removals increasing from 48% at pH 8.3
to 75% at pH 6.3. It should be noted that
in Figure 3-18, arsenic removal by the
Filox media was much higher than at the
end of the previously performed
equilibration experiments. This was
probably due to a relaxation in the
concentration gradient that occurs when
flow through adsorbent-packed media
bed is interrupted and then resumed.
Morevover, the longer contact time of
1.5 min used in the post-equilibration
experiments, compared with the 0.75
min contact time used in the
equilibration experiments, will also
result in increased arsenic adsorption by
the Filox media as seen in Figure 3-16.
39
-------
i
8
a
o
U
g
50
40
30
20
10
• As(III) Remaining
• Total Effluent As
Initial As(HI) = 50 fig/L
EBCT=1.5min
DO = 8.2 mg/L
Line of 90% Arsenic(III) Oxidation
PH
Figure 3-18. Effect of pH on As(III) oxidation with Filox media.
3.7.3 Filox: Effect of DO in the
absence of interfering reductants
In the absence of interfering reductants,
the concentration of dissolved oxygen in
the synthetic water had no effect on
As(III) oxidation by the Filox media
(Table 3-7, experiments 1-7). Similar
results were obtained for the higher
initial As(HI) concentration of 1000
ug/L (Table 3-7, experiments 19 and
20). This lack of effect is supported by
the studies of Scott and Morgan (1995)
who concluded that DO had no effect on
As(IH) oxidation by 8-MnO2.
Effect of Interfering
Synthetic
3.7.4 Filox:
Reductants
3.7.4.1 Low-DO (0.1 mg/L)
Water at 1.5 min EBCT
All of the interfering reductants studied
had an adverse effect on As(III)
oxidation in low-DO synthetic water at
pH 8.3 and EBCT of 1.5 min (Table 3-7,
experiments 8-13). Sulfide had the
greatest effect on As(III) oxidation,
which decreased from 99% with no
sulfide present to 62 and 56% at sulfide
levels of 1.0 and 2.0 mg/L, respectively.
Similarly, in the presence of 1.4 mg/L
TOC, As(III) oxidation was reduced to
79% compared with 99% when no TOC
was present.
3.7.4.2Low-DO (0.1 mg/L) Synthetic
Water at 6.0 min EBCT
To attenuate the effect of interfering
reductants in low-DO water, the EBCT
was increased from 1.5 to 6.0 min. At
an EBCT of 6.0 min, the effects of all of
the interfering reductants on As(III)
oxidation were completely attenuated
(Table 3-7, experiments 15-18), and
As(III) oxidation results matched those
when no interfering reductants were
present.
3.7.4.3High-DO (8.2 mg/L) Synthetic
Water at 1.5 min EBCT
Near-complete arsenic oxidation was
also obtained in the presence of
40
-------
interfering reductants when the synthetic
test water contained sufficient dissolved
oxygen as seen from Table 3-7,
experiments 21-24. When 8.2 mg/L DO
was present, As(III) oxidation results
matched those when no interfering
reductants were present.
5.7.5 Fttox: Effect of Low
Temperature in low-DO Synthetic
Water
Lowering the temperature of the
synthetic water from 24 °C (approximate
room temperature) to 8 °C had no effect
on arsenic oxidation with an oxidation
efficiency of 98.3% achieved at 8°C
compared with 99% at 24 °C (Table 3-7,
experiments 7 and 14).
3.8 UV Oxidation Results
Two UV units from different
manufacturers were tested for their
ability to oxidize As(III). Fifteen
experiments were performed using UV
to oxidize As(III) and the results are
summarized in Table 3-8.
Table 3-8. UV Oxidation Experiments.
#
UVDose Flow Rate Contact pH %As(III)
W-sec/cm2
UVUnitl: 32,000 ftw/c
1
2
3
4
5
6
7
8
UV
9
10
11
12
13
14
15
1.9
5.8
11.5
23.0
46.1
46.1
46.1
1.8a
mL/min Time (min)
:m? at a
288
96
48
24
12
12
12
310
Unit 2: 41, 200 juw/cm2 at a
3.9
5.8
11.5
23.0
46.1
46.1
46.1
310
209
105
52
26
26
26
design flow rate of 1890 mL/min
1 8.3
3 8.3
6 8.3
12 8.3
24 8.3
24 7.3
24 6.3
0.9 8.3
design flow rate of 3785 mL/min
1.6 8.3
2.3 8.3
4.7 8.3
9.3 8.3
18.7 8.3
18.7 7.3
18.7 6.3
Oxidation
4
14
27
58
73
71
64
100
2
5
12
29
43
40
27
a—Spiked with 1.0 mg/L sulfite, SO3", to verify reported catalytic effect of sulfite on UV
oxidation of As(III).
3.8.1 Unitl
Unit 1 (R-Can Environmental Inc.,
Canada) had a design flow rate of 0.5
gpm (1890 mL/min) and provided a UV
intensity of 32,000 uW/cm2. At a flow
rate of 288 mL/min (contact time of 1
41
-------
min), i.e., about 15% of the rated flow,
no significant oxidation was observed
(Table 3-8, experiments 1-7). A
maximum of 73% As(III) oxidation was
obtained at 12 mL/min flow rate (contact
time of 24 min), i.e., 0.6% of the rated
flow. This translates to an extremely
high energy input of 46,080,000 uw-
sec/cm2, whereas only 6,500 uw-
sec/cm2 is required to achieve a 99.9%
destruction level ofE.Coli.
To verify the reported catalytic effect of
sulfite on As(III) oxidation by UV (MSB
Technology Applications, Inc., Montana
and ANSTO, Australia (1997; Khoe et
al. (1997) and Khoe et al. (2000)), the
synthetic water was spiked with 1.0
mg/L of sulfite and allowed to stand for
30 minutes. The sulfite-spiked synthetic
water was then passed through Unit 1
where complete oxidation of As(III) was
obtained, whereas virtually no oxidation
occurred in the unspiked synthetic water
under the same conditions (Table 3-8,
experiment 8). Thus, sulfite played a
role in facilitating the oxidation of
As(III). The mechanism of sulfite-
facilitated As(TII) oxidation is a matter
of speculation. Sulfite is not an
oxidizing agent and control tests
performed with the sulfite-spiked water,
with the UV lamp turned off, showed no
As(III) oxidation. It is possible that
sulfite catalyzed the formation of free
radicals and thus assisted hi the
oxidation of As(III). The role of sulfite
in facilitating As(III) oxidation merits
further research.
3.8.2 Unit 2
Qualitatively, Unit 2 (Atlantic
Ultraviolet Corp.) with a design flow
rate of 1 gpm (3,785 mL/min) gave
results similar to those obtained using
Unit 1 (Table 3-8, experiments 9-15).
However, for the same UV doses, Unit 2
produced less oxidation than Unit 1.
The reasons for the difference in
performance between the two UV units
was not studied.
It should be noted that the off-the-shelf
UV units studied were designed for the
primary purpose of disinfection and,
therefore, were not optimized for As(III)
oxidation. Arsenic shows a strong
absorbance at 193.7 nm, which is the
wavelength used in AA units for arsenic
analysis. Therefore, a more appropriate
wavelength to study UV-oxidation of
As(III) would be near 193.7 nm. UV
systems, with peak intensity at 185 nm,
are commercially available and may be
more appropriate for such a study.
It should also be noted that the
difference in arsenic-oxidation
performance of the two UV units does
not imply that they would perform
differently for a disinfection-type
application.
42
-------
4. Summary and Conclusions
Bench-scale studies were performed to
assess the feasibility of using three- and
ten-times stoichiometric amounts (based
on As(m) concentration) of five
chemical oxidants, a solid-phase oxidant,
and UV radiation for As(IE) oxidation to
As(V). The effects of interfering
reductants including dissolved
manganese (0.2 g/L), dissolved iron (0.3
and 2.0 mg/), sulfide (1.0 and 2.0 mg/L)
and TOC (2.1 and 6.9 mg/L) on the
effectiveness of these oxidants was
examined. The conclusions of the one-
year lab study on As(in) oxidation
performed at the University of Houston
are summarized below.
(1) Chlorine rapidly oxidized As(HT) to
As(V) under all the conditions tested.
Iron and manganese had no measurable
effect on As(HI) oxidation. Although
sulfide and TOC slowed As(in)
oxidation by chlorine, complete
oxidation was still obtained in less than
one minute. Lowering the temperature
from 25 to 5 °C had no measurable
effect on As(HI) oxidation in the absence
of interfering reductants.
(2) Permanganate also rapidly oxidized
As(in) to As(V). Even in the presence
of interfering reductants, greater than
95% As(m) oxidation was achieved by
permanganate in < 51 seconds.
Lowering the temperature from 25 to 5 °
C had no measurable effect on As(H[)
oxidation in the absence of interfering
reductants.
(3) In the absence of interfering
reductants, ozone rapidly oxidized
As(ffl) in the pH range of 6.3-8.3. No
adverse effect was observed in the
presence of either dissolved manganese
or dissolved iron. Although complete
oxidation was obtained, the rate of
As(m) oxidation was considerably
slower in the presence of sulfide.
TOC had the greatest adverse effect on
As(m) oxidation by ozone. In the
presence of 6.9 mg/L TOC in As(m)-
spiked Lake Houston water, only 34%
As(ni) oxidation was produced in 21
seconds. Thus, the presence of TOC had
a quenching effect on ozone. When the
TOC in the Lake Houston was reduced
by dilution with synthetic test water to
2.1 mg/L, complete oxidation of As(ni)
was observed in 27 seconds. Lowering
the temperature from 25 to 5 °C had no
measurable effect on As(HT) oxidation in
the absence of interfering reductants.
(4) Chlorine dioxide was, surprisingly,
ineffective for As(in) oxidation. A
three-fold stoichiometric dose of
chlorine dioxide produced only 20-30%
oxidation in 21 seconds and produced no
additional oxidation thereafter. Even a
100-times stoichiometric dose produced
only 76% oxidation in 5 minutes. The
limited oxidation that was observed was
probably due to the presence of chlorine
as a contaminant in the chlorine dioxide
stock solutions as chlorine is known to
be a by-product of the chlorine dioxide
generation process.
(5) Monochloramine was ineffective as
an oxidant for As(m) confirming the
findings of other researchers. While
43
-------
limited As(III) oxidation resulted when
monochloramine was formed in-situ, no
oxidation was observed when preformed
monochloramine was used. This
suggests that when chlorine is dosed into
an As(III)-containing solution in the
presence of excess ammonia, a fraction
of that chlorine reacts with As(III) before
it is completely quenched by ammonia to
form monochloramine.
(6) Filox media was found to be very
effective for As(III) oxidation under
most of the conditions tested. In the
absence of interfering reductants, greater
than 95% As(III) oxidation was achieved
in both low-and high-DO waters at
contact times as short as 1.5 min (15
gpm/ft2 hi a 3-ft deep bed). In addition
to As(III) oxidation, the Filox media also
removed arsenic by adsorption onto the
media, but the adsorption decreased as
the media came into equilibrium with the
feed water.
As(III) oxidation by Filox was
adversely affected hi the presence of all
of the interfering reductants tested in
low-DO water at an EBCT of 1.5 min
(2.4 gpm/ft2) with sulfide exhibiting the
greatest effect. The effects of interfering
reductants were completely attenuated
by either increasing the contact time to 6
min or by increasing the DO to 8.2
mg/L. As(III) concentrations as high as
1000 |o.g/L were efficiently oxidized (>
95%) in both low- and high-DO waters
at pH 8.3 in the absence of interfering
reductants.
(7) UV radiation alone was ineffective
for As(III) oxidation unless extremely
high UV doses, (7000 times the UV dose
required for E.Coli inactivation) were
used. Even with such a high UV dose,
only 73% As(III) oxidation was
observed. However, as described in a
patented process, the presence of sulfite
provided for the rapid and quantitative
oxidation of As(III). The mechanism by
which sulfite promotes the oxidation of
As(III) was not studied here.
44
-------
5. References
Amy, G. et al. Arsenic Treatability
Options and Evaluation of Residuals
Management Issues (90771).
AWWARF, Denver (2000).
Catherine, H.A. The Electrochemical
Oxidation of As(III). A Consecutive
Electron Transfer Reaction. Journal
of Physical Chemistry, Vol. 71, No.
2, p 268-274 (1967).
Clifford, D.A. and Lin, C.C. Arsenic
Removal from Drinking Water in
Hanford, California. Preliminary
Report, Department of Civil and
Environmental Engineering,
University of Houston (1986).
Clifford, D.A. Ion-exchange and
Inorganic Adsorption. Water
Quality and Treatment, Chapter 9,
5th edition, McGraw Hill (1999).
Clifford, D.A. and Lin, C.C. Arsenic(III)
and Arsenic(V) Removal from
Drinking Water in San Ysidro, New
Mexico, EPA/600/S2-91/011,
USEPA, Cincinnati, Ohio (1991).
Clifford, D.A. and Zhang, Z. Arsenic
chemistry and speciation. Proc.
1993 Water Quality Technology
Conference, AWWA, Denver, CO
(1994).
Clifford, D.A. et al. Final Report:
Phases 1 and 2, City of Albuquerque
Arsenic Study, University of
Houston—Department of Civil and
Environmental Engineering,
Houston, TX (1997).
Clifford, D.A. et al. Arsenic Removal
by Ion-exchange With and Without
Brine Reuse. Proc. AWWA
Inorganic Reductants Workshop, San
Antonio, TX(1998a).
Clifford, D.A. et al. Final Report: Phase
3, City of Albuquerque Arsenic
Study, University of Houston—
Department of Civil and
Environmental Engineering,
Houston, TX (1998b).
Driehaus, W. et al. Oxidation of
Arsenate(III) with Manganese
Oxides in Water Treatment. Water
Research, Vol. 29, No. 1, p 297-305
(1995).
Everett, K.G. and Skoog, D.A. Study of
Uncatalyzed Oxidation of
Arsenic(III) by Cerium(IV) in
Perchloric Acid Medium. Analytical
Chemistry, Vol. 43, No. 12, p 1541-
1547(1971).
Ferguson, J.F., and Gavis, J. A Review
of the Arsenic Cycle hi Natural
Waters. Water Research, 6:1259-
1274(1972).
Frank, P.L. Arsenic(III) Oxidation and
Removal from Drinking Water. MS
Thesis. Department of Civil and
Environmental Engineering,
University of Houston (1984).
Frank, P.L., and Clifford, D.A. Arsenic
(III) Oxidation and Removal from
Drinking Water. Summary Report,
EPA/600/S2-86/021 (1986).
Ghurye, G.L. et al. Iron
Coagulation/Microfiltration for
Arsenic Removal. Proc. AWWA
Inorganic Reductants Workshop, San
Antonio, TX (1998).
Ghurye, G.L. et al. Combined Arsenic
and Nitrate Removal by Ion-
exchange. J American Water Works
Association, Vol. 91, No. 10, p 85 -
96 (1999).
45
-------
Gupta, B. et al. Kinetics and Mechanism
of the Silver(I)-catalyzed Oxidations
of Arsenic(III) and Antimony(III)
with Peroxodiphosphate hi Acetate
Buffers. Journal of Chemical
Society, Dalton Transactions, No. 9,
pi 873-1876 (1984).
Hathaway, S.W. and Rubel, F.
Removing Arsenic from Drinking
Water. J American Water Works
Association, Vol. No. 79, No.8
(1987).
Hering, J.G. et al. Arsenic removal by
ferric chloride. J American Water
Works Association, Vol. 88, No. 4, p
155 -167 (1996a).
Hering, J.G. et al. Arsenic Removal by
Enhanced Coagulation and
Membrane Processes. (90706).
AWWARF, Denver (1996b).
Johnson, D. C. and Bruckenstein, D.C.
A Study of the Kinetics of the
Oxidation of Arsenic(III) by
Electrogenerated Iodine in Alkaline
Media. Journal of American
Chemical Society, Vol. 90, No. 24, p
6592-6596 (1968).
Khoe, G.H. et al. Photoassisted
oxidation of species in solution.
U.S. Patent No. 5,688,378 (1997).
Khoe, G.H. et al. Removal of Arsenic
Using Advance Oxidation Processes.
Presented at the 2000 SME Annual
Meeting & Exhibit, Salt Lake City,
Utah (2000).
Knocke, W. et al. Alternative oxidants
for the removal of soluble iron and
manganese. Prepared for the AWWA
Research Foundation, Denver, CO
(1990).
Mohan, D. et al. Kinetics and
Mechanism of the Oxidation of
Arsenic(IH) by Hexacyanoferrate(III)
in Alkaline Medium. Inorganic
Chemistry, Vol. 16, No. 5, p 1020-
1029 (1977).
Moore, J. N. et al. Reaction Scheme for
the Oxidation of As(III) to As(V) by
Birnessite. Clays and Clay Minerals,
Vol. 38, No. 5, p 549-555 (1990).
MSB Technology Applications, Inc. and
Australian Nuclear Science &
Technology Organization. Final
Report—Arsenic Oxidation
Demonstration Project for US EPA
Mine Waste Technology Program
(MWTP) Activity III, Project 7
(1997).
Nishida, S. and Kimura, M. Kinetic
Studies of the Oxidation Reaction of
Arsenic(III) to Arsenic(V) by
Peroxodisulphate Ion in Aqueous
Alkaline Media Journal of Chemical
Society, Dalton Transactions, No. 2,
p 357-360 (1989).
Oscarson, D. W. et al. Kinetics of
Oxidation of Arsenite by Various
Manganese Dioxides. Soil Science
Society of America, Vol. 47, p 644-
648 (1983).
Scott, M.J. and Morgan, J.J. Reactions at
Oxide Surfaces. 1. Oxidation of
As(III) by Synthetic Birnessite.
Environmental Science and
Technology, Vol. 29, No. 8, p 1898-
1905 (1995).
Sen Gupta, K.K. and Chakladar, J.K.
Kinetics of the Chromic Acid
Oxidation of Arsenic(III). Journal of
Chemical Society, Dalton
Transactions, No. 2, p 222-225
(1989).
Simms, J. et al. Arsenic Removal
Studies and the design of a 20,000
m3 per day plant in the UK. Proc.
AWWA Inorganic Reductants
Workshop, Albuquerque, NM
(2000).
46
-------
Standard Methods for the Examination
of Water and Waste-water, 18th
Edition, (1992).
U.S. EPA. Preparation aids for the
development of RREL Category III
Quality Assurance Project Plans.
Office of Research and
Development, Risk Reduction
Engineering Laboratory, Cincinnati,
OH (1991).
White, G.C. The Handbook of
Chlorination. 2nd Edition, Van
Nostrand Reinhold Co., NY (1986).
47
-------
Appendix A. Preconditioning and Regeneration of IX Filter
A.I Manufacturer-
Recommended Preconditioning
(1) Center the filter on the base of a
vacuum filter holder.
(2) Wet the filter with 10 mL of acetone
for 30 sec, and then apply vacuum to
dry the filter.
(3) Add 10 mL of isopropanol and allow
filter to soak for 30 sec. Apply
vacuum to dry the filter.
(4) Finally, add 10 mL of methanol.
Draw approximately 3-4 mL of
methanol through the filter under
vacuum. Vent vacuum and allow
filter allowed to soak in methanol for
60 seconds. Reapply vacuum and
add 30 mL of reagent grade water to
rinse methanol from the filter.
Ensure that the filter does not dry by
leaving 3-5 mL of reagent grade
water on the filter.
A.2 IX Filter Regeneration—
UHMethod
All preconditioned and used filters were
regenerated (converted to the chloride
form) according to the procedure
outlined below.
(5) Mount the filter on the base of a
vacuum filtration apparatus and
place a 0.22 um filter (Millipore, 47
mm, Type GS) on top of the IX
Empore filter. Add 20 mL of 1 M
HC1 and pull approximately 3-4 mL
of HC1 through the filter under
vacuum. Vent the vacuum and allow
the filter to soak for about 60
seconds. Reapply vacuum to draw
the remaining acid through the filter
at a flow rate of 20 mL/min or less.
(6) Add 20 mL of 1 M NaCl and pull
approximately 3-4 mL of the salt
solution through the filter. Vent the
vacuum and allow the filter to soak
for about 60 seconds. Reapply
vacuum and draw the remaining salt
solution through the filter at a flow
rate of 20 mL/min or less.
(7) To rinse the concentrated NaCl out
of the filter, add 20 mL of 0.005 M
NaCl and draw about 15 mL through
the filter at a flow rate of 20 mL/min
or less. The IX filter is now ready to
use for the As(III)/(V) speciation
tests.
(8) Once preconditioned and
regenerated, the filter should not be
allowed to dry for an extended
period of time. One way to prevent
drying is to place the filter in a
beaker or a sealed plastic bag
containing a 0.005 M NaCl solution.
48
-------
Appendix B. Testing Oxidation Reactor Set-up
The procedures followed for testing the
reactor set-up for As(V)/As(III)
separation are described in this section.
(1) Pour 500 mL of the synthetic water
containing either As(IH) or As(V)
into the oxidation reactor. Close the
reactor.
(2) Place the IX filter in the filter
holder. Place a 0.22 urn filter on top
of the IX filter and assemble the on-
line filter holder.
(3) Pressurize the reactor to 15 psi using
nitrogen gas. Open outlet valve and
allow the test solution to flow
through the filters.
(4) Discard the first 10 mL of the
effluent. Collect the rest of the
effluent in 10 (or 25) mL aliquots.
Acidify the 10 mL aliquots using 50
uJL of cone, nitric acid and store at 4
°C until ready for analysis. After
collecting the desired volume of the
filter effluent, close the outlet valve.
The test is now completed. To prepare
for the next test, perform the following
procedures.
(5) Vent the nitrogen gas pressure and
disassemble the filter holder.
Transfer the IX filter along with the
0.22 urn filter atop it to a vacuum
filtration apparatus.
(6) Regenerate the IX filter as outlined
in the Filter Regeneration Method
described in Appendix A.
(7) Simultaneously, clean the reactor by
rinsing four times with 250 mL of DI
water. Then fill the reactor with 500
mL of DI water. Close the reactor
and pressurize to 15 psi. Allow
approximately 100 mL of flow from
the reactor through an empty filter
holder. This rinses out the tubing
between the reactor and the filter
holder, the filter holder itself, and the
final section of tubing between the
filter holder and the fraction
collector.
(8) Discard the used 0.22 jam filter from
step 7 and transfer the regenerated IX
filter into the rinsed in-line filter
holder. Place a new 0.22 um filter
on top of the IX filter. Assemble the
filter holder together and connect to
the oxidation reactor. Allow
approximately 200 mL of the DI
water to pass through the assembled
filter holder. This is an additional
rinse of all the tubing, the filters, and
the filter holder. The IX filter is now
ready to speciate As(III)/As(V).
Discard the remaining DI water in
the reactor. The reactor is now ready
to receive a fresh test solution.
49
-------
Appendix C. Variable-DO Experiments
C.1 High-DO Chemical
Oxidation Experiments
The experimental procedure for the high-
DO oxidation experiments, which were
run in duplicate, is outlined below.
Briefly, each experiment was performed
in duplicate along with a control
experiment for each set of duplicates.
The control experiment was performed
in exactly the same manner as the
oxidation experiment except that no
oxidant was present.
(1) Prepare 2 L of the test solution with
the appropriate concentration of
As(III). Rinse the reactor twice with
50 mL of the test solution. Then
place 500 mL of the test solution in
the reactor. Close the reactor and
pressurize to 15 psi with nitrogen
gas. Start the magnetic stirrer.
(2) Place a conditioned, chloride-form
IX filter, fresh or regenerated, into
the in-line filter holder. Place a 0.22
jam filter on top of the IX filter, and
assemble the in-line filter holder.
Set the tuner on the fraction collector
at 0.1 min, i.e., 6 seconds.
(3) Inject the required quantity of the
oxidant. Immediately, open the outlet
valve allowing the test solution to
flow through the IX filter into one of
the 15-mL sample tubes in the
fraction collector. (The flow rate
obtained using 15 psi nitrogen gas
pressure was approximately 20
mL/min).
(4) Discard the first 4 mL (12 seconds)
of the effluent. Start the fraction
collector and collect samples (~ 2
mL aliquots) every six seconds for
the first minute of the reaction.
(Samples were collected in the
intervals of 12-18, 18-24, 24-30 sec,
etc. were labeled with the median
tune of sampling as 15, 21, 27 sec
and so on). Then stop the flow by
closing the outlet valve and stop the
fraction collector. Restart the flow
by opening the outlet valve at 1 min
57 sec and allow flow to waste up to
2 min 07 sec. Collect flow for the
next 10 sec, i.e., from 2 min 07 sec
to 2 min 17 sec (median sample time
of 2 min 12 sec (132 sec) from the
start of the reaction). Stop the flow
and repeat to get samples at 192,
252, and 312 sec. Acidify the 2.0
mL aliquots using 10 uL of cone.
nitric acid and store at 4 °C until
ready for analysis.
(5) At the end of 317 sec, close the
outlet valve. The experiment is
complete at this point.
To prepare for the duplicate, follow the
procedure described below.
(6) Vent the nitrogen gas pressure and
disassemble the filter holder.
Transfer the IX filter along with the
0.22 |j.m filter atop it to a vacuum
filtration apparatus.
(7) Regenerate the IX filter as outlined in
the IX Regeneration Method in
Appendix A.
(8) Clean the reactor by rinsing four
times with 250 mL of DI water.
Then fill the reactor with 500 mL of
DI water. Close the reactor and
pressurize. Allow approximately
50
-------
100 mL of flow from the reactor
through an empty filter holder.
(9) Transfer the regenerated IX filter into
the in-line filter holder. Place a new
0.22 mm filter on top of the IX filter.
Assemble the filter holder together
and connect to the oxidation reactor.
Allow approximately 200 mL of the
DI water to pass through the
assembled filter holder. Collect the
last 10 mL of rinse and analyze as
reactor blank. Discard the remaining
DI water in the reactor. The reactor
is now ready to receive a fresh test
solution.
(10) Duplicate the same experiment by
following steps 1 through 5.
After completing the repeat experiment,
a control run was performed to verify
that no oxidation occurred in the absence
of oxidant and that no residual oxidant
was left in the reactor, i.e., to verify that
the rinsing procedures used were
effective in purging the entire reactor
set-up of any leftover oxidant.
(10) Once again, clean the reactor as
described before and fill with 500
mL of test solution spiked with
As(III). Close the reactor and
pressurize with nitrogen gas.
Regenerate and place the IX filter in
the filter holder. Start the magnetic
stirrer. Start the timer and allow 5
minutes to pass before opening the
outlet valve and allowing flow
through the filter holder. Waste the
first 4 mL and collect the next 10 mL
of flow and analyze for arsenic. This
sample served as the control for the
set of repeat experiments.
C.2 Low-DO Chemical
Oxidation Experiments
The low-DO experiments were necessary
only when dissolved iron or sulfide was
added to the synthetic test water. The
low-DO experiments were performed in
the same manner as the high-DO
experiments except that the rinse water
and the synthetic water was sparged with
extra-dry-grade nitrogen gas to produce
a low-DO synthetic water containing <
0.1 mg/L of dissolved oxygen).
The additional steps (to the procedure
for the high-DO oxidation experiments)
necessary to perform the low-DO
experiments are described below.
(1) Add 500 mL of the test solution to
the reactor and close the reactor.
Sparge with extra dry grade nitrogen
gas for 30 minutes.
(2) Briefly stop sparging and add the
appropriate dose of dissolved iron
(Fe(II)) or sulfide. In the case of
dissolved iron, resume sparging for
about 5 minutes and then close the
reactor while maintaining nitrogen
pressure. However, after the
addition of sulfide, resume sparging
very briefly (no more than 5-15
seconds to prevent sulfide stripping)
and immediately close the reactor.
Pressurize with nitrogen gas to 15
psi. Perform the oxidation
experiment as described before.
51
-------
Appendix D. Solid-Phase (Filox) Experiments
The procedures used for the various
Filox experiments are described in detail
hi this appendix. The procedures used
for the variable-EBCT and variable-pH
experiments was the same. In order to
perform Filox experiments with low-
DO, the oxidation reactor was used.
Essentially, as La the chemical oxidation
experiments, the low-DO synthetic water
was prepared in the oxidation reactor as
described in Appendix C and instead of
adding any chemical oxidant to the
reactor, the reactor was maintained under
nitrogen pressure and the low-DO
synthetic water was pumped from the
reactor to the Filox column.
D.I Variable-EBCT and
Variable-pH Experiments
(1) Two liters (2L) of synthetic water
(previously sparged with air for 15
min) containing 50 \igfL of As(III)
was prepared in a 2-L volumetric
flask. The average DO of this
synthetic water was 8.2 mg/L.
(2) The high-DO synthetic water was
then pumped from the volumetric
flask through the Filox column. The
flow rate was adjusted to the desired
setting (starting with 16 mL/min,
EBCT of 0.75 mm) following which
5 BV (60 mL) of the synthetic water
was passed through the column.
Then, approximately 25 mL of the
Filox column effluent was collected,
acidified, and analyzed as Total
Effluent As. Flow was then
switched to the DC filter holder and
three consecutive 1-BV intervals
were speciated, acidified, and
analyzed for unoxidized As(III).
To prepare the filter for the next EBCT
or pH, the IX filter was regenerated
according to the procedure described in
Appendix A. To test the next variable,
the flow rate was reset to the desired
value and steps (1) - (2) were repeated.
The procedure for the variable-pH
experiments was the same as for the
variable-EBCT experiments except that
the pH of the feed solution was adjusted
to the desired level (6.3, 7.3, and 8.3)
using 1M HC1 solution.
After the desired experiments were
completed, flow through the Filox
column was stopped. The remaining
contents of the volumetric flask were
then speciated for As(III)/As(V) to
ensure that all of the arsenic that was fed
to the Filox column was As(III).
D.2 Low-DO Filox Experiments
(1) 500 mL of synthetic water, without
any sulfate, was sparged for 30
minutes with extra-dry-grade
nitrogen gas to strip out the dissolved
oxygen. It was then pumped through
the Filox-media column and through
the IX filter connected to the outlet
of the column. After purging the
media and the filter holder with
approximately 350 mL of the low-
DO water, the reactor was emptied
and refilled with the usual
composition synthetic water (Table
1). Sulfate was excluded because the
Empore filter has a finite speciation
capacity of approximately 100-150
52
-------
mL before it is exhausted, primarily
by sulfate, and requires regeneration.
(2) After 30 minutes, nitrogen
sparging was briefly stopped and the
appropriate amount of As(III) and
reductant were added to the sparged
water. Sparging was resumed and
continued for 15-20 more minutes
and the low-DO water was then
pumped through the Filox media
column with continued sparging.
When testing the nitrogen-sparged
synthetic water in the presence of
sulfide, no sparging was performed
after sulfide had been added to the
test water. Rather the reactor was
sealed and maintained under a
nitrogen atmosphere. Once sulfide
was introduced into the synthetic
water, sparging was stopped to avoid
stripping sulfide from the synthetic
water.
(3) After 5 BV (60 mL) had passed
through the Filox media, an effluent
sample collected at the outlet of the
Filox column, was acidified and
analyzed for "Total Effluent As"
exiting the Filox column. The flow
was then switched to the IX filter.
The first 5 mL of flow from the IX
filter was wasted and then three
consecutive 1-BV samples were
collected, acidified with cone nitric
acid, and analyzed for arsenic. A 25-
mL sample from the closed reactor
was collected, acidified, and
analyzed for feed As. The reactor
was then emptied and rinsed with DI
water and prepared for the next
experiment.
(4) To verify that all of the arsenic
fed to the Filox column was As(III),
the oxidation reactor was filled with
synthetic water and sparged for 30
minutes followed by the addition of
an appropriate amount of As(III) and
reductant, if any. Sparging was
continued for a further 15-20 minutes
(except in the presence of sulfide)
and the synthetic water containing 50
ug/L As(III) was pumped from the
reactor straight to the IX filter. The
effluent from the IX filter was
collected, acidified, and analyzed as
Control As(III). Such controls were
performed (one control/set of
duplicates) for the varying pH and
EBCT experiments as well as each of
the interfering reductant
experiments.
53
-------
Appendix E. Chlorine Oxidation Data
Run#
E15.01-
E15.03-
E15.05-
E15.07-
E15.09-
E15.ll-
E15.13-
E15.15-
E15.17-
15.02:
15.04:
15.06:
15.08:
15.10:
15.12:
15.14:
15.16:
15.18:
E15.19-15.20:
E15.21-15.22:
Description
No interfering reductants:
No interfering reductants:
No interfering reductants:
Mn(II) = 0.2 mg/L; Dose =
Fe(II) = 0.3 mg/L; Dose =
Fe(II) = 2.0 mg/L; Dose =
Sulfide =1.0 mg/L; Dose
Sulfide = 2.0 mg/L; Dose
TOC = 6.9 mg/L; Dose =
Water
No interfering Reductants
pH = 8.3
No interfering reductants:
Dose = 3 x As(III); pH = 8.3
Dose = 3 x As(III); pH = 7.3
Dose = 3xAs(IH);pH = 6.3
= 10xAs(III);pH = 8.3
10 x As(III); pH = 8.3
10xAs(III);pH = 8.3
= 10xAs(III);pH = 8.3
= 10xAs(III);pH = 8.3
10 x As(III); pH = 8.3; Lake Houston
As(IH) = 1000 ug/L; Dose = 3 x As(III);
5 °C; Dose = 3 x As(III); pH = 8.3
54
-------
Table E-l. Residual As(III) Cone, vs Time for Chlorine Experiments.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
15.01
50.0
1.6
1.2
0.6
0.5
0.3
0.5
0.2
0.5
0.3
0.5
0.1
0.2
0.1
0.2
15.02
50.0
1.6
1.2
0.6
0.5
0.3
0.5
0.2
0.5
0.3
0.5
0.1
0.2
0.1
0.2
B
15.03
50.0
2.2
1.3
0.7
0.1
0.5
0.6
0.5
0.5
0.2
0.2
0.1
0.1
0.1
0.2
.esidual /
15.04
50.0
2.1
1.3
0.6
0.3
0.2
0.3
0.1
0.6
0.2
0.1
0.1
0.2
0.5
0.2
is(III) Co
15.05
50.0
14.0
9.1
6.1
3.7
2.3
1.4
0.7
0.1
0.3
0.1
0.0
0.2
0.1
0.3
tic., ug/L
15.06
50.0
14.0
9.6
8.1
2.9
1.6
1.3
0.7
0.3
0.5
0.1
0.6
0.2
0.1
0.1
for Run t
15.07
50.0
4.0
2.5
2.0
1.6
1.3
1.1
0.8
0.6
0.3
0.3
0.3
0.1
0.3
0.3
f
15.08
50.0
4.6
3.1
1.4
1.6
1.1
0.1
0.5
0.1
0.1
0.3
0.3
0.3
0.6
0.3
15.09
50.0
0.5
0.
0.
0.
0.
0.
0.1
0.1
0.1
0.1
0.1
0.2
0.8
0.3
15.10
50.0
1.3
0.2
0.1
0.3
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Table E-l. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
15.11
50.0
0.8
0.2
0.
0.
0.
0.
0.
0.
0.
0.1
0.1
0.1
0.1
0.1
15.12
50.0
1.2
0.1
0.1
0.
0.
0.
0.
0.
0.
0.1
0.1
0.1
0.1
0.1
R
15.13
50.0
18.0
14.0
7.2
6.1
5.5
3.5
2.7
1.0
0.8
0.4
0.8
0.8
1.0
0.6
.esidual /
15.14
50.0
20.0
15.0
8.9
6.4
4.0
3.2
2.4
1.1
0.8
0.6
0.3
0.3
0.8
0.8
LS(HI) Co
15.15
50.0
24.0
19.0
15.0
12.0
8.2
5.3
1.7
1.5
1.1
0.5
0.3
0.5
0.6
0.6
nc., ug/L
15.16
50.0
26.0
19.0
16.0
14.0
11.0
7.2
3.2
2.1
1.7
0.9
0.3
0.1
0.3
0.1
for Run ^
15.17
50.0
1.5
1.5
.2
.2
.0
.2
.3
.2
.2
.2
2.3
1.5
2.3
1.0
[
15.18
50
2.8
2.8
1.9
1.3
1.0
0.1
1.3
2.1
2.8
3.6
4.1
2.8
3.7
3.6
15.19
1000
10.0
3.7
1.1
3.1
4.1
4.3
3.5
3.7
4.5
3.3
3.5
2.1
15.20
1000
7.5
1.7
5.3
3.3
2.5
2.9
4.9
0.9
3.5
1.5
3.1
2.5
55
-------
Table E-l. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
Rui
H&
15.21
50
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
i#
IL
15.22
50
0.1
0.1
0.1
0.1
0.1
o.i
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
56
-------
Appendix F. Permanganate Oxidation Data
Run #
E16.01
E16.03
E16.05
E16.07
E16.09
E16.1 1
E16.13
E16.15
E16.17
E16.19
16.02
16.04
16.06
16.08
16.10
16.12
16.14
16.16
16.18
16.20
E16.21-16.22
Description
No interfering reductants:
No interfering reductants:
No interfering reductants:
Mn(II) = 0.2 mg/L; Dose
Fe(II) = 0.3 mg/L; Dose =
Fe(II) = 2.0 mg/L; Dose =
Sulfide - 1.0 mg/L; Dose
Sulfide = 2.0 mg/L; Dose
TOC = 6.9 mg/L; Dose =
No interfering Reductants
As(IH);pH = 8.3
No interfering reductants:
Dose = 3 x As(III); pH = 8.3
Dose = 3 x As(III); pH = 7.3
Dose = 3 x As(III); pH = 6.3
10 x As(III); pH = 8.3
10 x As(III); pH = 8.3
10 x As(III); pH = 8.3
= 10 x As(III); pH = 8.3
= 10 x As(III); pH = 8.3
10 x As(III); pH = 8.3
; As(III) = 1000 ug/L; Dose = 3 x
5 °C; Dose = 3 x As(III); pH = 8.3
57
-------
Table F-l. Residual As(III) Cone, vs Time for Permanganate Experiments.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
16.01
50.0
1.9
1.2
0.7
0.3
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
16.02
50.0
2.6
1.8
1.2
0.5
0.2
0.1
0.2
0.3
0.1
0.1
0.1
0.1
0.1
0.1
B
16.03
50.0
2.1
1.4
0.7
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
.esidual A
16.04
50.0
1.7
0.8
0.6
0.3
0.2
0.2
0.1
0.2
0.1
0.1
0.1
0.1
0.1
0.1
is(III) Co
16.05
50.0
6.0
3.9
2.0
0.9
0.7
0.2
0.7
0.
0.
0.
0.
0.
0.1
0.1
nc., ug/L
16.06
50.0
6.7
5.3
3.9
1.9
0.6
0.2
0.2
0.2
0.1
0.2
0.2
0.3
0.5
0.2
for Run it
16.07
50.0
2.4
1.5
0.7
0.3
0.
0.
0.
0.
0.
0.1
0.1
0.3
0.3
0.3
[
16.08
50.0
3.0
1.3
0.4
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.1
0.1
16.09
50.0
3.1
1.5
0.7
0.1
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
16.10
50.0
3.2
1.8
0.6
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Table F-l. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
16.11
50.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.0
0.1
0.1
0.1
0.1
0.1
0.1
16.12
50.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
R
16.13
50.0
5.7
5.0
4.3
4.0
3.2
2.9
2.6
1.4
1.0
0.6
0.3
0.3
0.4
0.4
.esidual A
16.14
50.0
6.9
5.5
4.7
4.1
3.8
3.1
2.1
1.4
1.3
0.6
0.6
0.6
0.1
0.6
is(III) Co
16.15
50.0
11.8
10.7
9.0
6.5
5.7
4.4
3.7
2.4
1.8
1.4
0.4
0.1
0.5
0.6
nc., ug/L
16.16
50.0
10.7
9.0
8.2
7.2
5.1
3.2
.5
.4
.4
.3
.1
0.6
0.6
0.6
for Run ri
16.17
50.0
1.5
0.0
1.4
1.5
1.0
0.4
3.4
0.2
1.5
1.9
1.6
1.4
2.1
0.8
f
16.18
50.0
0.4
0.4
0.2
0.1
0.1 ,
0.1
0.1
0.1
0.2
0.1
1.2
1.5
2.1
2.8
16.19
1000
8.9
1.5
1.9
2.9
3.3
2.5
1.7
2.9
2.9
2.3
0.9
0.9
16.20
1000
13.0
0.9
2.5
3.7
1.7
1.3
2.9
0.9
0.9
3.5
1.7
2.9
58
-------
Table F-l. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
Rui
Hg
16.21
50.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
i#
IL
16.22
50.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
59
-------
Appendix G. Chlorine Dioxide Oxidation Data
Run # Description
E17.01-17.02: No interfering reductants: pH 8.3
E17.03-17.04: No interfering reductants: pH 7.3
E17.05-17.06: No interfering reductants: pH 6.3
E17.07-17.08: Mn(II) = 0.2 mg/L; Dose = 3 x As(III); pH = 8.3
E17.09-17.10: Fe(II) = 0.3 mg/L; Dose = 3 x As(III); pH = 8.3
E17.11-17.12: Fe(II) = 2.0 mg/L; Dose = 3 x As(IH); pH = 8.3
E17.13-17.18: Oxidation of Fe(II); Repeat of Knocke (1990) experiments
Not included in Table G-l
E17.19-17.20: Repeat of E17.01-17.02; No interfering reductants: pH 8.3
E17.21-17.22: No interfering reductants: pH 8.3; 3 x C12 @ t=l'45"
E17.23-17.24: No interfering reductants: pH 8.3; Deaerated Test Solution
E17.25-17.26: No interfering reductants: pH 8.3; Dose = 10 x As(III)
E17.27-17.28: No interfering reductants: pH 8.3; Dose = 100 x As(III)
60
-------
Table G-l. Residual As(III) Cone, vs Time for Chlorine Dioxide Experiments.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
17.01
50.0
38.9
37.7
37.9
37.5
38.9
37.7
37.5
37.5
38.4
38.6
39.6
37.2
38.4
38.0
17.02
50.0
42.0
40.6
40.3
40.3
40.8
39.4
39.9
39.9
40.5
40.6
40.3
39.4
39.1
39.1
F
17.03
50.0
47.0
46.8
46.8
47.5
46.6
47.3
46.3
46.8
46.5
47.2
47.8
47.3
47.5
47.3
.esidual A
17.04
50.0
48.4
49.0
46.8
47.0
47.3
47.0
47.2
47.2
47.5
47.0
46.3
46.3
45.8
45.8
LS(III) Co
17.05
50.0
47.0
47.3
46.5
46.1
45.6
47.7
48.4
46.8
46.5
46.7
47.5
47.7
46.3
48.2
nc., jig/L
17.06
50.0
49.0
49.0
48.7
48.4
48.0
48.0
47.0
47.0
46.8
46.3
46.3
44.6
44.6
45.4
for Run i
17.07
50.0
37.2
35.6
35.3
31.7
35.1
34.4
34.3
34.1
34.3
34.6
34.3
33.7
33.6
34.6
^
17.08
50.0
36.3
35.8
35.3
33.9
33.6
33.9
33.2
31.2
32.7
32.9
33.2
33.4
32.2
33.2
17.09
50.0
30.8
29.3
28.4
27.0
26.7
27.2
27.5
26.7
26.5
27.0
27.0
27.0
28.0
26.7
17.10
50.0
29.4
26.8
26.3
26.7
27.0
26.7
26.0
25.8
24.9
25.5
28.0
26.7
27.0
27.0
Table G-l. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
17.11
50.0
23.9
21.7
21.5
20.8
20.1
20.3
19.8
20.8
20.8
21.0
21.0
20.6
21.8
19.8
17.12
50.0
21.8
19.8
19.4
17.7
18.0
18.4
18.6
19.1
18.6
19.4
19.4
19.1
18.9
19.1
P
17.19
50.0
35.4
34.8
34.8
35.4
35.4
35.2
34.6
34.8
34.6
35.4
35.4
33.8
34.6
33.3
.esidual A
17.20
50.0
38.8
36.6
38.8
36.4
39.2
39.2
39.0
38.6
38.8
38.6
35.2
36.6
36.0
35.4
LS(III) Co
17.21
50.0
40.4
39.6
38.8
38.4
38.2
37.2
36.6
36.2
36.4
35.8
1.5
0.1
0.1
0.1
nc., ng/L
17.22
50.0
40.2
40.4
39.0
39.6
39.4
38.0
38.2
38.4
37.0
37.4
0.9
0.1
0.1
0.1
for Run tf
17.23
50.0
40.2
39.6
39.2
38.4
38.4
37.6
37.8
37.1
37.3
37.3
37.1
38.0
38.0
37.4
[
17.24
50.0
41.1
40.5
40.2
40.0
39.6
38.4
38.6
38.6
38.2
38.4
38.4
38.4
38.6
39.0
17.25
50
35.5
36.0
35.2
35.2
33.6
33.4
32.0
31.0
31.5
29.9
30.6
29.6
29.9
30.1
17.26
50
36.0
35.9
36.2
34.8
31.8
32.0
32.9
34.3
31.1
30.6
31.8
30.4
29.0
28.5
61
-------
Table G-l. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
Rui
V-&
17.27
50.0
26.1
24.2
24.0
23.6
22.8
22.2
22.1
22.4
21.2
20.8
15.6
13.2
12.5
12.1
i#
fL
17.28
50.0
25.2
25.9
24.5
24.3
23.5
21.9
22.8
20.7
18.9
18.4
14.7
14.0
10.9
12.3
62
-------
Appendix H. Monochloramine Oxidation Data
Run # Description
E18.01-18.02: No interfering reductants: pH 8.3: in situ monochloramine
El 8.03-18.04: No interfering reductants: pH 7.3: in situ monochloramine
E18.05-18.06: No interfering reductants: pH 6.3: in situ monochloramine
El8.07-18.08: No interfering reductants: pH 8.3: preformed monochloramine
63
-------
Table H-l. Residual As(III) Cone, vs Time for Monochloramine Experiments
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
18.01
50.0
30.6
30.1
29.4
29.4
29.6
29.9
28.9
29.6
29.8
29.8
29.8
29.1
29.4
29.8
F
18.02
50.0
33.3
33.1
33.6
33.6
31.5
32.2
32.4
32.2
32.4
32.9
31.5
31.5
31.5
31.9
esidual A
18.03
50.0
31.3
31.5
31.3
31.0
30.6
30.5
30.6
31.0
31.3
30.3
29.4
30.1
29.6
30.8
LS(III) Co
18.04
50.0
29.4
29.1
29.1
28.9
28.5
28.2
28.9
28.9
30.5
28.7
28.5
28.2
28.4
28.4
nc., ng/L
18.05
50.0
33.3
30.6
29.1
28.7
28.7
29.1
29.2
30.1
29.8
29.8
30.1
29.1
29.1
29.4
for Run ri
18.06
50.0
31.9
32.6
31.5
30.8
30.5
30.8
30.8
30.5
30.5
31.0
30.1
29.8
29.1
29.6
18.07
50.0
47.6
48.6
48.9
48.9
49.2
49.9
50.2
49.4
49.4
48.7
49.2
50.2
49.1
49.9
18.08
50.0
47.4
49.1
49.6
50.1
49.9
49.1
49.6
50.1
50.6
49.4
49.4
49.1
49.7
50.2
64
-------
Appendix I. Ozone Oxidation Data
Run # Description
E19.01-19.02: No interfering reductants: Dose = 3 x As(III); pH = 8.3
E19.03-19.04: No interfering reductants: Dose = 3 x As(III); pH = 7.3
E19.05-19.06: No interfering reductants: Dose = 3 x As(III); pH = 6.3
E19.07-19.08: Mn(II) = 0.2 mg/L; Dose = 10 x As(III); pH = 8.3
E19.09-19.10: Fe(II) = 0.3 mg/L; Dose = 10 x As(III); pH = 8.3
E19.11-19.12: Fe(II) = 2.0 mg/L; Dose = 10 x As(III); pH = 8.3
E19.13-19.14: Sulfide = 1.0 mg/L; Dose = 10 x As(III); pH = 8.3
E19.15-19.16: Sulfide = 2.0 mg/L; Dose = 10 x As(III); pH = 8.3
E19.17-19.18: TOC = 6.9 mg/L; Dose = 10 x As(IH); pH = 8.3
E19.19 : Repeat of E19.01-19.02; No interfering reductants: Dose = 3 x As(III);
pH = 8.3
E19.20 : Repeat of E19.17-19.19; TOC = 6.9 mg/L; Dose = 10 x As(IH); pH = 8.3
E19.21-19.22: TOC = 2.1 mg/L; Dose = 10 x As(III); pH = 8.3
E19.23-19.24: No interfering reductants: 5 °C; Dose = 3 x As(III); pH = 8.3
E19.25-19.26: Repeat of E19.21-19.22; TOC = 2.1 mg/L; Dose = 10 x As(III); pH = 8.3
65
-------
Table 1-1. Residual As(III) Cone, vs Time for Ozone Experiments.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
19.01
50.0
1.9
1.2
1.2
1.1
1.1
0.9
0.5
0.7
0.9
0.9
0.9
0.9
0.7
0.7
19.02
50.0
1.1
0.5
0.4
0.
0.
0.
0.
0.
0.1
0.1
0.1
0.1
0.1
0.1
B
19.03
50.0
0.7
0.7
0.5
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.4
0.1
0.1
.esidual A
19.04
50.0
0.4
0.2
0.1
0.1
0.
0.
0.
0.
0.
0.
0.4
0.1
0.1
0.1
Ls(III) Co
19.05
50.0
1.6
1.1
0.4
0.2
0.1
0.1
0.1
0.4
0.
0.
0.
0.2
0.
0.
nc.,,ug/L
19.06
50.0
0.9
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
for Run ^
19.07
50.0
0.8
0.5
0.5
0.2
0.3
0.5
0.2
0.2
0.1
0.1
0.3
0.1
0.2
0.1
f
19.08
50.0
1.2
0.8
0.5
0.3
0.3
0.2
0.1
0.1
0.1
0.1
0.1
0.2
0.1
0.1
19.09
50.0
0.5
0.2
0.1
0.1
0.2
0.1
0.1
0.1
0.2
0.1
0.1
0.1
0.1
0.1
19.10
50.0
0.2
0.2
0.2
0.1
0.1
0.2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Table 1-1. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
19.11
50.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
19.12
50.0
0.
0.
0.
0.
0.
0.
0.
0.1
0.1
0.1
0.1
0.1
0.1
0.1
R
19.13
50.0
16.4
11.1
8.3
6.1
4.7
3.3
2.5
2.0
2.0
1.3
0.9
0.4
0.2
0.1
esidual A
19.14
50.0
14.0
9.9
6.6
5.2
4.2
2.6
1.1
0.6
0.1
0.1
0.3
0.1
0.2
0.4
LS(III) Co
19.15
50.0
24.4
21.1
18.3
14.9
12.5
10.2
7.3
6.1
5.4
3.3
2.0
2.1
1.3
1.4
nc., ng/L
19.16
50.0
26.4
23.8
19.7
16.1
13.3
12.3
9.2
6.4
5.9
5.1
2.2
1.4
0.9
0.6
for Run *
19.17
50.0
37.8
36.9
34.7
35.4
34.7
35.8
35.6
34.9
35.1
34.9
34.9
35.1
34.9
35.2
19.18
50.0
34.3
34.3
33.8
32.8
32.8
31.9
32.3
31.9
32.1
31.7
31.4
31.2
30.4
31.2
19.19
50.0
3.1
2.6
2.8
2.4
1.5
2.4
1.5
2.1
1.4
1.2
0.8
0.7
0.1
0.3
19.20
50.0
35.7
35.2
35.3
35.9
35.0
34.8
35.5
35.2
34.3
35.7
35.3
35.0
34.6
35.0
66
-------
Table 1-1. Continued.
Sample
Interval
(sec)
12-18
18-24
24-30
30-36
36-42
42-48
48-54
54-60
60-66
66-72
127-137
187-197
247-257
307-317
Median
Time
(sec)
0
15
21
27
33
39
45
51
57
63
69
132
192
252
312
19.21
50.0
3.1
1.8
1.5
1.0
0.8
0.8
0.8
0.8
0.8
1.0
0.1
0.1
0.1
0.1
Residual i
19.22
50.0
1.4
1.0
0.7
0.5
0.5
0.5
0.3
0.1
0.1
0.1
0.1
0.1
0.7
0.1
\s(III) Co
19.23
50.0
3.8
3.1
2.6
2.6
2.4
2.4
2.2
2.4
2.4
2.1
0.1
0.1
0.1
0.1
QC., Ug/L
19.24
50.0
4.3
3.1
3.1
2.8
2.4
2.2
2.1
1.7
1.5
1.0
0.3
0.5
0.8
1.0
for Run #
19.25
50.0
5.0
4.3
3.1
2.7
2.2
0.9
1.2
0.7
1.1
2.2
1.2
1.8
1.4
0.7
19.26
50.0
2.2
0.7
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.9
0.7
0.9
0.2
67
-------
Appendix J. Filox Oxidation Data
Run # Description
E20.01 :No interfering reductants: pH = 8.3, EBCT = 0.75 min, High DO
E20.02:No interfering reductants: pH = 8.3, EBCT = 1.5 min, High DO
E20.03:No interfering reductants: pH = 8.3, EBCT = 3.0 min, High DO
E20.04:No interfering reductants: pH = 8.3, EBCT = 6.0 min, High DO
E20.05:RepeatofE20.1
E20.06:Repeat of E20.2
E20.07:RepeatofE20.3
E20.08:Repeat of E20.4
£20.09:2000 BV Filox Run, No interfering reductants: pH = 8.3, EBCT = 0.75
min, High DO
E20.10:No interfering reductants: pH = 7.3, EBCT = 1.5 min, High DO
E20.1 l:No interfering reductants: pH = 6.3, EBCT = 1.5 min, High DO
E20.12:No interfering reductants: pH = 7.3, EBCT = 1.5 min, Low DO
E20.13:Repeat of E20.12
E20.14:Mn(II) = 0.2 mg/L; pH = 8.3, EBCT = 1.5 min, Low DO
E20.15:Fe(II) = 0.3 mg/L; pH = 8.3, EBCT = 1.5 min, Low DO
E20.16:Fe(II) = 2.0 mg/L; pH = 8.3, EBCT = 1.5 min, Low DO
E20.17:Sulfide = 1.0 mg/L; pH = 8.3, EBCT = 1.5 min, Low DO
E20.18:Sulfide = 2.0 mg/L; pH = 8.3, EBCT = 1.5 min, Low DO
E20.19:TOC = 1.4 mg/L; pH = 8.3, EBCT = 1.5 min, Low DO
E20.20:No interfering Reductants; 5 °C, pH = 8.3, EBCT = 1.5 min, Low DO
E20.21:No interfering Reductants; As(III) = 1000 ug/L, pH = 8.3, EBCT = 1.5
min, Low DO
E20.22:No interfering Reductants; As(III) = 1000 ug/L, pH = 8.3, EBCT = 1.5
min, High DO
E20.23:Mn(II) = 0.2 mg/L; pH = 8.3, EBCT = 1.5 min, High DO
E20.24 :Sulfide = 1.0 mg/L; pH = 8.3, EBCT = 1.5 min, High DO
E20.25:Sulfide = 2.0 mg/L; pH = 8.3, EBCT = 1.5 min, High DO
E20.26:TOC = 1.4 mg/L; pH = 8.3, EBCT = 1.5 min, High DO
E20.27:Mn(TI) = 0.2 mg/L; pH = 8.3, EBCT = 6.0 min, Low DO
E20.28:Sulfide = 1.0 mg/L; pH = 8.3, EBCT = 6.0 min, Low DO
E20.29:Sulfide = 2.0 mg/L; pH = 8.3, EBCT = 6.0 min, Low DO
E20.30:TOC = 1.4 mg/L; pH = 8.3, EBCT = 6.0 min, Low DO
68
-------
Table J-l. Residual As(III) vs Effluent As Concentration for Filox Experiments.
Sample
ID
E20.01
E20.02
E20.03
E20.04
E20.05
E20.06
E20.07
E20.08
E20.10
E20.ll
E20.12
E20.13
E20.14
E20.15
E20.16
E20.17
E20.18
E20.19
E20.20
E20.21
E20.22
E20.23
E20.24
E20.25
E20.26
E20.27
E20.28
E20.29
E20.30
Residual As(III)
Concentration
Hg/L
2.0
0.1
0.1
0.4
2.6
1.2
1.2
0.3
0.1
0.1
0.3
0.5
10.9
9.5
9.3
19.3
22.1
10.4
0.8
33.2
49.7
0.8
0.8
1.9
1.2
0.1
0.2
1.4
0.1
Total Effluent
As
Hg/L
MM
MM
NM
NM
27.3
25.9
22.5
18.2
16.9
12.4
24.5
39.4
43.8
40.5
43.1
47.5
45.3
46.4
31.8
55-1.9
499.3
24.7
12.0
11.4
22.3
24.5
21.3
28.8
26.3
MM: Not Measured
E20.09
BV
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
Residual As(III)
Concentration
Hg/L
2.1
2.0
2.8
3.5
3.3
2.5
2.3
3.0
2.8
3.0
3.2
3.8
2.8
3.2
3.7
3.0
3.7
3.5
3.0
3.5
Total Effluent
As
ug/L
36.8
40.1
41.3
42.1
43.1
40.2
41.6
43.5
42.6
43.3
45.3
44.3
42.6
42.5
44.3
44.2
44.2
44.5
46.2
45.9
69
-------
Appendix K. UV Oxidation Data
Run # Description
E21.01:UV1: Flow Rate = 48 mL/min, Contact Time =
E21.02:UV1: Flow Rate = 96 mL/min, Contact Time =
E21.03:UV1: Flow Rate = 288 mL/min, Contact Time
E21.04:Repeat of E21.03
E21.05:Repeat of E21.02
E21.06:RepeatofE21.01
E21.07:UV1: Flow Rate = 24 mL/min, Contact Time =
E21.08:UV1: Flow Rate = 12 mL/min, Contact Time =
E21.09:UV1: Flow Rate = 12 mL/min, Contact Time =
E21.10:UV1: Flow Rate = 12 mL/min, Contact Time =
E21.11 :UV1: Flow Rate = 310 mL/min, Contact Time
Sulfite=1.0mg/L
E22.01:UV2: Flow Rate = 310 mL/min, Contact Time
E22.02:UV2: Flow Rate = 209 mL/min, Contact Time
E22.03:UV2: Flow Rate = 104 mL/min, Contact Time
E22.04:UV2: Flow Rate = 52 mL/min, Contact Time =
E22.05:UV2: Flow Rate = 26 mL/min, Contact Time =
E22.06:UV2: Flow Rate = 26 mL/min, Contact Time =
E22.07:UV2: Flow Rate = 26 mL/min, Contact Time =
6 min, pH = 8.3
•• 3 min, pH = 8.3
= 1 min, pH = 8.3
= 12 min, pH = 8.3
= 24 min, pH = 8.3
= 6 min, pH = 7.3
= 6 min, pH = 6.3
= 0.9 min, pH = 8.3
= 1.6min,pH = 8.3
= 2.3 min, pH = 8.3
= 4.7 min, pH = 8.3
= 9.3 min, pH = 8.3
= 18.7 min, pH = 8.3
= 18.7min,pH = 7.3
= 18.7min,pH = 6.3
70
-------
Table K-l. Residual As(III) Cone, for UV Experiments.
UV Unit 1
Sample
ID
E21.01
E21.02
E21.03
E21.04
E21.05
E21.06
E21.07
E21.08
E21.09
E21.10
E21.ll
UV Intensity
mW-sec/cm^
11520
5760
1920
1920
5760
11520
23040
46080
46080
46080
1780
Residual As(IH)
Concentration
Hg/L
35.7
42.2
48.8
13.5
21.2
37.3
43.4
47.7
14.5
17.9
0.1
UV Unit 2
Sample
ID
E22.01
E22.02
E22.03
E22.04
E22.05
E22.06
E22.07
UV Intensity
mW-sec/cm2
3380
5760
11520
23040
46080
46080
46080
Residual As(III)
Concentration
Hg/L
28.5
35.8
44.0
47.4
49.2
29.8
36.7
71
-------
Appendix L. As(III) Stock Solution
An As(III) stock solution containing
88.0 mg/L As(III) was prepared in a
synthetic water of a composition similar
to the synthetic test water shown in
Table 2-1 except that no calcium
chloride was added to the stock solution.
Calcium chloride was not added as the
high pH of the As(III) stock solution
(due to added bicarbonate and silicate)
would have resulted in the precipitation
of calcium carbonate.
Approximately 500 mL of reagent grade
water was added to a 1-L volumetric
flask. All of the ions except calcium
chloride were added to the flask.
Finally, the required amount of sodium
m-arsenite (Sigma Chemical Co.) was
added to give a final As(III)
concentration of approximately 88 mg/L
and the volume of the As(III) stock
solution was made up to 1.0 L. The pH
of this As(III) stock solution was 9.1.
The stock solution was then refrigerated
(4 °C). When required, the necessary
volume of this As(III) stock solution was
added to the synthetic test water to
provide a final As(III) concentration of
50 or 1000 ng/L.
72
-------
Appendix M. QC Data
The following QC samples were
analyzed:
(1) QC standards
These were prepared by the QA/QC
Officer for this project, Anthony Tripp,
and served as "in-house" QC check
standards. Four standards were prepared
at a time and any one of these standards
were analyzed along with the four WAL
standards during analysis. The
concentrations of these QC standards
were within the range of 1.0-11.0 ug/L
As. These standards were analyzed
without dilution. Results from all the
QC samples are shown in Table M-l.
(2) WS Standards
Four WS standards were preserved in a
0.2 M nitric acid solution and measured
once during a batch of samples. The
concentrations of these standards are
shown in Table 2-3. Standards WS 037,
WS 038, and WS 041 were always
diluted 10-fold before analysis.
Standard WS 040 was diluted 10- and
20-fold before analysis. Results from all
the WS samples are shown in Table M-
2.
(3) Spikes
Standards WS 037, WS 038, and WS
041 were always diluted 10-fold and
spiked with 2.0 ug/L As. Standard WS
041 was diluted 20-fold and then spiked
with 2.0 ug/L As. Results of arsenic
recoveries from all the WS-spiked
samples are shown hi Table M-3.
73
-------
Table M-l. Results of QC Analysis
Run#
E19.13-19.16
E19.13-19.16
E19.13-19.16
E19.13-19.16
E19.13-19.16
E19.13-19.16
E20.1-20.4
E20.1-20.4
E20. 1-20.4
E20.5-20.8
E20.5-20.8
E20.5-20.8
E20. 14-20.22
E20. 14-20.22
E20.14-20.22
E20. 14-20.22
E20.14-20.22
E20. 14-20.22
E20.14-20.22
Number = 19
Run#
E16. -16.6
E16. -16.6
E16. -16.6
E16. -16.6
E16. -16.6
E17. -17.6
E17. -17.6
E17.1-17.6
E17.1-17.6
E17.1-17.6
E17.1-17.6
E17.1-17.6
E18.7-18.8
El 8.7-1 8.8
E18.7-18.8
E18.7-18.8
E18.7-18.8
E18.7-18.8
E18.7-18.8
E18.7-18.8
Number =20
Date
7/9/1999
7/9/1999
7/9/1999
7/9/1999
7/9/1999
7/9/1999
9/25/1999
9/25/1999
9/25/1999
9/28/1999
9/28/1999
9/28/1999
10/26/1999
10/26/1999
10/26/1999
10/26/1999
10/26/1999
10/26/1999
10/26/1999
Dilution
Factor
1
1
1
1
1
1
1
1
1
1
QC Cone
Hg/L
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
1.00
Measured Cone
ug/L
0.95
0.94
0.99
0.97
1.01
0.97
0.92
0.94
0.94
0.96
0.98
0.96
0.95
0.94
0.95
0.97
1.01
0.99
1.02
Avg = 0.97
SD = 0.03
Range = 0.92 - 1 .02 (-8 to + 2%)
Date
3/26/1999
3/26/1999
3/26/1999
3/26/1999
3/26/1999
5/13/1999
5/13/1999
5/13/1999
5/13/1999
5/13/1999
5/13/1999
5/13/1999
6/15/1999
6/15/1999
6/15/1999
6/15/1999
6/15/1999
6/15/1999
6/15/1999
6/15/1999
Avg
SD
Range
Dilution
Factor
1
1
1
1
1
1
1
1
QC Cone
Hg/L
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
1.02
Measured Cone
Ug/L
0.90
0.93
0.84
0.86
0.86
0.95
0.99
0.97
0.97
0.99
1.02
1.06
1.03
1.07
0.98
0.96
0.98
0.98
1.00
1 1.02 0.98
= 0.97
= 0.06
= 0.84 - 1.07 (-16 to + 7%)
74
-------
Table M-l. Results of QC Analysis (Contd)
Run#
E16.7-16.12
E16.7-16.12
E16.7-16.12
E16.7-16.12
E16.7-16.U
E17.7-17.12
E17.7-17.12
E17.7-17.12
E17.7-17.12
E17.7-17.12
E17.7-17.12
E17.25-17.2S
E17.25-17.28
E17.25-17.28
E17.25-17.28
E17.25-17.28
E17.25-17.28
E18.1-18.6
E18.1-18.6
E18.1-18.6
E18.1-18.6
Number = 21
Date
3/29/1999
3/29/1999
3/29/1999
3/29/1999
3/29/1999
5/15/1999
5/15/1999
5/15/1999
5/15/1999
5/15/1999
5/15/1999
6/2/1999
6/2/1999
6/2/1999
6/2/1999
6/2/1999
6/2/1999
6/11/1999
6/11/1999
6/11/1999
6/11/1999
Dilution
Factor
1
1
1
1
QC Cone
Hg/L
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
2.96
Measured Cone
ug/L
2.88
3.04
2.92
3.14
3.00
2.89
2.89
2.98
3.01
2.98
3.01
2.97
2.97
2.92
2.94
3.01
2.92
2.92
2.90
2.97
2.95
Avg =2.96
SD = 0.06
Range =2.88 -3. 14 (-3 to + 6%)
75
-------
Table M-l. Results of QC Analysis (Contd)
Run#
E1S.17-15.18
E15.17-15.18
E15.17-15.18
E15.17-15.18
E15.17-15.18
E15.17-15.18
E15.17-15.18
E15.17-15.18
E15.21-15.22
E15.21-15.22
E15.21-15.22
E15.21-15.22
E15.21-15.22
E15.21-15.22
E20.9
E20.9
E20.9
E20.9
E20.9
E20.23-20.30
E20.23-20.30
E20.23-20.30
E20.23-20.30
E20.23-20.30
E20.23-20.30
Number = 25
Date
9/27/1999
9/27/1999
9/27/1999
9/27/1999
9/27/1999
9/27/1999
9/27/1999
9/27/1999
9/11/1999
9/11/1999
9/11/1999
9/11/1999
9/11/1999
9/11/1999
10/7/1999
10/7/1999
10/7/1999
10/7/1999
10/7/1999
11/15/1999
11/15/1999
11/15/1999
11/15/1999
11/15/1999
11/15/1999
Dilution
Factor
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
QC Cone
ug/L
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
3.03
Measured Cone
Hg/L
2.90
3.03
3.06
3.06
2.97
2.99
2.95
3.06
2.97
3.07
3.09
2.92
2.96
2.94
2.94
3.05
2.90
2.92
2.94
2.90
2.92
2.97
2.95
3.00
3.09
Avg =2.98
SD = 0.06
Range = 2.90 - 3.09 (-2 to + 2%)
76
-------
Table M-l. Results of QC Analysis (Contd)
Run#
E19. 19-19.24
E19. 19-19.24
E19. 19-19.24
E19. 19-19.24
E19.19-19.24
E19.19-19.24
E19.19-19.24
E19.19-19.24
E20.10-20.12
E20. 10-20.12
E20. 10-20. 12
E20.10-20.12
E21.4-21.10
E21.4-21.10
E21.4-21.10
E21.4-21.10
E22. 1-22.7
E22.1-22.7
E22. 1-22.7
E22. 1-22.7
E22. 1-22.7
Number = 21
Date
9/10/1999
9/10/1999
9/10/1999
9/10/1999
9/10/1999
9/10/1999
9/10/1999
9/10/1999
10/13/1999
10/13/1999
10/13/1999
10/13/1999
1/12/2000
1/12/2000
1/12/2000
1/12/2000
2/2/2000
2/2/2000
2/2/2000
2/2/2000
2/2/2000
Dilution
Factor
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
QC Cone
Hg/L
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
5.84
Measured Cone
Hg/L
5.83
5.90
5.83
5.78
5.85
5.94
5.99
5.71
5.68
5.77
5.71
5.75
5.49
5.67
5.80
5.73
5.82
5.89
5.82
5.88
5.93
Avg = 5.80
SD =0.11
Range = 5.49 - 5.99 (-6 to + 3%)
77
-------
Table M-l. Results of QC Analysis (Contd)
Run#
E16.13-16.16
E16.13-16.16
E16.13-16.16
E16.13-16.16
E17.19-17.22
E17.19-17.22
El7.l9-n.22
E19.1-19.6
E19.1-19.6
E19.1-19.6
E19.1-19.6
E19.1-19.6
E19.1-19.6
E19.1-19.6
E19.1-19.6
Number =15
Date
3/31/1999
3/31/1999
3/31/1999
3/31/1999
5/26/1999
5/26/1999
5/26/1999
7/1/1999
7/1/1999
7/1/1999
7/1/1999
7/1/1999
7/1/1999
7/1/1999
7/1/1999
Dilution
Factor
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
QC Cone
ug/L
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
5.97
Measured Cone
ug/L
5.98
5.84
6.06
6.04
5.86
6.00
6.02
5.86
5.84
5.83
5.95
5.95
5.90
5.98
5.95
Avg , =5.94
SD = 0.08
Range = 5.83 - 6.06 (-2 to + 2%)
Run#
E19.24-19.30
E19.24-19.30
E19.24-19.30
E19.24-19.30
E19.24-19.30
E19.24-19.30
E19.24-19.30
E19.24-19.30
E20.13
E20.13
E20.13
E21.1-21.3
E21. 1-21.3
E21.1-21.3
E21. 1-21.3
Number = 15
Date
9/18/1999
9/18/1999
9/18/1999
9/18/1999
9/18/1999
9/18/1999
9/18/1999
9/18/1999
10/14/1999
10/14/1999
10/14/1999
12/30/1999
12/30/1999
12/30/1999
12/30/1999
Dilution
Factor
1
1
1
QC Cone
ug/L
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
9.88
Measured Cone
ug/L
9.26
9.42
9.69
9.66
9.49
9.51
9.53
9.55
9.36
9.57
9.50
9.55
9.75
9.95
9.75
Avg =9.57
SD =0.17
Range = 9.26 - 9.95 (-6 to + 1%)
78
-------
Table M-l. Results of QC Analysis (Contd)
Run#
E15.13-15.16
E15.13-15.16
E15.13-15.16
E15.13-15.16
E17.23-17.24
E17.23-17.24
E17.23-17.24
E17.23-17.24
E19.7-19.12
E19.7-19.12
E19.7-19.12
E19.7-19.12
E19.7-19.12
E19.7-19.12
E19.7-19.12
E19.7-19.12
Number = 16
Date
3/20/1999
3/20/1999
3/20/1999
3/20/1999
6/1/1999
6/1/1999
6/1/1999
6/1/1999
7/6/1999
7/6/1999
7/6/1999
7/6/1999
7/6/1999
7/6/1999
7/6/1999
7/6/1999
Dilution
Factor
1
1
1
1
1
1
1
1
1
1
1
QC Cone
ug/L
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
10.29
Measured Cone
Hg/L
9.97
9.85
9.77
9.67
9.78
9.85
9.97
10.11
10.04
9.97
9.96
9.85
9.80
9.76
9.73
9.96
Avg = 9.88
SD = 0.12
Range = 9.67 - 10. 1 1 (-6 to -2%)
79
-------
Table M-2. Results of WS Standards Analysis (WS 037)
Run#
E03-04
E05
E07-10
E07-10
El 1-12
E14
E15.1-15.6
E15.7-15.12
E1S.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
E17.1-17.6
E17.7-17.12
E17.19-17.22
E17.23-17.24
E17.25-17.28
E18.1-18.6
E18.7-18.8
E19.1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20. 1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20.14-20.22
E20.23-20.30
E21. 1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
Number = 38
Date
11/26/1998
1/27/1998
12/4/1998
12/4/1998
12/17/1998
2/22/1999
3/8/1999
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
Dilution
Factor
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
EPA Cone
ug/L
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
49.3
Measured Cone
ug/L
46.31
46.35
48.56
49.51
49.30
49.96
47.80
47.01
48.99
47.21
47.28
47.16
46.23
47.94
47.47
46.80
48.76
47.33
48.08
46.84
46.38
47.98
50.10
46.25
47.27
48.41
49.09
49.19
49.00
49.25
48.34
48.83
45.01
48.50
50.13
48.87
48.94
50.39
Avg =48.1
SD = 1.3
Range = 45.0 - 50.4 (-9 to +2%)
80
-------
Table M-2. Results of WS Standards Analysis (WS 038)
Run#
E07-10
E07-10
Ell-12
E14
E15.1-15.6
E15.7-15.12
E15.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
E17.1-17.6
E17.7-17.12
E17. 19-17.22
E17.23-17.24
E17.25-17.28
E18.1-18.6
E18.7-18.8
E19.1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20.1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20. 14-20.22
E20.23-20.30
E21. 1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
Number = 36
Date
12/4/1998
12/4/1998
12/17/1998
2/22/1998
3/8/1999
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
Dilution
Factor
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
EPA Cone
ug/L
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.
83.
83.
83.
83.
83.
83.
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
83.1
Measured Cone
ug/L
79.44
80.38
73.50
77.59
76.67
72.97
76.19
74.29
76.94
74.76
73.80
75.05
74.66
73.77
75.33
75.30
76.70
73.88
74.73
75.67
77.85
73.69
75.70
77.51
76.89
76.48
77.12
75.95
78.03
74.66
74.41
76.74
76.32
75.49
78.29
77.82
Avg = 76.0
SD = 1.7
Range =73.0 -80.4 (-12 to -3%)
81
-------
Table M-2. Results of WS Standards Analysis (WS 040)
Run#
E07-10
E07-10
El 1-12
E14
E15.1-15.6
E15.7-15.12
E15.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
E17.1-17.6
E17.7-17.12
E17.19-17.22
E17.23-17.24
E17.25-17.28
E18.1-18.6
E18.7-18.8
E19. 1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20. 1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20. 14-20.22
E20.23-20.30
E21.1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
Number = 36
Date
12/4/1998
12/4/1998
12/17/1998
2/22/1998
3/8/1999
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
Dilution
Factor
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
EPA Cone
H&/L
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
Measured Cone
"g/L
107.48
108.66
103.27
101.13
90.99
105.36
99.44
95.47
95.71
94.56
96.34
97.35
103.58
98.84
105.19
101.27
99.13
95.51
103.07
98.44
98.80
97.09
99.13
101.21
97.30
105.25
98.60
97.03
100.99
97.22
94.45
99.51
99.11
96.26
98.74
99.01
Avg =99.5
SD =3.9
Range = 91.0 - 108.7 (-1 1 to +7%)
82
-------
Table M-2. Results of WS Standards Analysis (WS 040) (Contd)
Run#
E15.17-15.18
E15.21-15.22
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20. 1-20.4
E20.5-20.8
E20.9
E20. 10-20. 12
E20.13
E20. 14-20.22
E20.23-20.30
E21.1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
Number = 17
Date
9/27/1999
9/11/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
Dilution
Factor
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
EPA Cone
Hg/L
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
102
Measured Cone
Hg/L
96.27
96.36
97.43
99.02
100.65
98.54
104.23
99.08
98.84
100.82
95.19
95.02
100.77
100.61
96.88
100.37
99.01
Avg = 98.8
SD =2.4
Range = 95.0 - 1 04.2 (-7 to +2%)
83
-------
Table M-2. Results of WS Standards Analysis (WS 041)
Run#
E07-10
E07-10
Ell-12
E14
E15.1-15.6
E15.7-15.12
E15.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
E17.1-17.6
E17.7-17.12
E17.19-17.22
E17.23-17.24
E17.25-17.28
E18.1-18.6
E18.7-18.8
E19.1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20. 1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20.14-20.22
E20.23-20.30
£21.1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
Number = 35
Date
12/4/1998
12/4/1998
12/17/1998
2/22/1998
3/8/1999
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
Dilution
Factor
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
EPA Cone
ug/L
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
65.6
Measured Cone
ug/L
66.24
67.18
63.26
63.27
63.27
64.47
65.56
61.58
61.40
60.03
59.58
64.49
64.73
66.73
64.63
63.99
63.94
59.75
66.06
63.75
63.21
63.67
59.68
63.22
63.90
66.96
61.72
62.17
62.32
63.38
60.36
63.56
63.40
62.94
64.06
63.39
Avg = 63.4
SD = 2.0
Range = 59.6 - 67.2 (-9 to +2%)
84
-------
Table M-3. Recoveries of Spiked WS Standards
Run#
E18.1-18.6
E18.7-18.8
E19.1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20.1-20.4
E20.5-20.8
E20.9
E20. 10-20. 12
E20.13
E20. 14-20.22
E20.23-20.30
E21. 1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
E14
E15.1-15.6
E15.7-15.12
E15.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
E17.1-17.6
E17.7-17.12
E17.19-17.22
E17.23-17.24
E17.25-17.28
Date
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
2/22/1999
3/8/1999
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
Sample
ID
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
WS037
Dilution
Factor
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
Unspiked Cone
Hg/L
4.63
4.79
5.00
4.62
4.72
4.84
4.90
4.91
4.90
4.92
4.83
4.82
4.50
4.85
5.01
4.88
4.89
5.03
4.99
4.93
4.70
4.89
4.72
4.72
4.71
4.62
4.79
4.74
4.69
4.87
4.77
4.80
4.68
Spiked Cone
Hg/L
6.72
6.87
6.95
6.79
6.83
6.91
6.84
6.92
6.83
6.86
6.78
6.86
6.57
6.87
7.00
6.79
6.96
6.78
6.65
6.93
6.86
7.00
6.58
6.87
6.76
6.59
6.71
6.84
6.78
6.86
6.93
7.07
6.92
%
Recovery
104.2
103.4
97.1
108.2
105.1
103.7
96.6
99.9
96.7
96.9
97.5
101.5
103.5
101.0
99.6
95.2
103.2
87.3
82.9
100.0
108.0
105.1
93.0
106.9
102.4
98.5
95.9
104.7
103.9
99.2
108.1
113.1
111.6
E18.1-18.6
E18.7-18.8
E19.1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20. 1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20. 14-20.22
E20.23-20.30
E21. 1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
7.47
7.56
7.78
7.36
7.57
7.75
7.68
7.64
7.71
7.59
7.80
7.46
7.41
7.67
7.63
7.54
7.82
7.78
9.52
9.31
9.69
9.26
9.53
9.75
9.54
9.84
9.71
9.72
9.70
9.54
9.30
9.72
9.51
9.58
9.89
9.68
102.5
87.6
95.4
95.0
98.2
100.2
93.0
109.9
100.3
106.3
94.9
104.1
94.6
102.7
94.2
101.7
103.2
95.3
85
-------
E14
E15.1-15.6
E1S.7-15.12
E15.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
E17.1-17.6
E17.7-17.12
E17.19-17.22
E17.23-17.24
E17.25-17.28
2/22/1998
3/8/1999,
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
WS038
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
7.75
7.49
7.30
7.61
7.42
7.69
7.47
7.38
7.50
7.46
7.37
7.53
7.52
7.66
7.38
9.47
9.49
9.30
9.74
9.28
9.44
9.47
9.48
9.47
9.68
9.60
9.58
9.75
9.75
9.30
86.0
100.0
100.0
106.3
93.0
87.8
99.9
105.0
98.3
111.1
111.6
102.7
111.0
104.4
95.9
E20.1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20.14-20.22
E20.23-20.30
E21. 1-21.3
E21.4-21.10
E21.ll
E22. 1-22.7
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
WS040
WS040
WS040
WS040
WS040
WS040
WS040
WS040
WS040
WS040
WS040
20
20
20
20
20
20
20
20
20
20
20
5.21
4.95
4.94
5.04
4.75
4.75
5.03
5.03
4.84
5.01
4.95
E18.1-18.6
E18.7-18.8
E19.1-19.6
E19.7-19.12
E19.13-19.16
E19.19-19.24
E19.24-19.30
E20. 1-20.4
E20.5-20.8
E20.9
E20.10-20.12
E20.13
E20.14-20.22
E20.23-20.30
E21.1-21.3
E21.4-21.10
E21.ll
E22.1-22.7
E14
E15.1-15.6
E15.7-15.12
E15.13-15.16
E15.17-15.18
E15.19-15.20
E15.21-15.22
E16.1-16.6
E16.7-16.12
E16.13-16.16
6/11/1999
6/15/1999
7/1/1999
7/6/1999
7/9/1999
9/10/1999
9/18/1999
9/25/1999
9/28/1999
10/7/1999
10/13/1999
10/14/1999
10/26/1999
11/15/1999
12/30/1999
1/12/2000
2/8/2000
2/2/2000
2/22/1998
3/8/1999
3/16/1999
3/20/1999
9/27/1999
5/8/1999
9/11/1999
3/26/1999
3/29/1999
3/31/1999
WS041
WS041
WS041
WS 041 -
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
WS041
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
10
6.60
6.37
6.32
6.36
5.96
6.32
6.38
6.69
6.17
6.21
6.23
6.33
6.03
6.35
6.34
6.29
6.40
6.33
6.32
6.56
6.45
6.55
6.15
6.14
6.00
5.96
6.44
6.47
7.26
7.08
6.99
7.04
6.78
6.80
7.00
7.11
6.94
7.11
7.06
8.47
8.46
8.17
8.17
8.05
8.37
8.53
8.83
8.35
8.22
8.28
8.36
7.94
8.25
8.27
8.17
8.39
8.24
8.20
8.56
8.22
8.78
8.03
8.17
8.08
8.01
8.53
8.67
102.6
106.5
102.9
100.1
101.5
102.6
98.4
104.1
105.0
104.9
105.9
93.4
104.2
92.8
• 90.5
104.3
102.8
107.4
107.2
109.2
100.3
102.7
101.5
95.5
95.0
96.9
94.1
99.6
95.3
94.2
100.0
88.5
111.3
93.9
101.9
104.1
102.5
104.3
110.1
86
-------
E17.1-17.6
E17.7-17.12
E17.19-17.22
E17.23-17.24
E17.25-17.28
Number =110
5/13/1999
5/15/1999
5/26/1999
6/1/1999
6/2/1999
WS041
WS041
WS041
WS041
WS041
10
10
10
10
10
6.67
6.46
6.39
6.39
5.97
8.57
8.60
8.34
8.48
7.87
95.3
107.0
97.2
104.4
95.1
Avg = 100.6
SD =6.1
Range =82.9-113.1
87
-------
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Environmental Protection Agency/ORD
National Risk Management
Research Laboratory
Cincinnati, OH 45268
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