Treatment Technologies for
Arsenic Removal
On January 18, 2001, the United States
Environmental Protection Aagency (EPA)
finalized the maximum contaminant level
(MCL) for arsenic at 0.01 mg/L. The EPA
subsequently revised the rule text to express
the MCL as 0.010 mg/L (10 |Jg/L). The final rule
requires all community and non-transient, non-
community water systems to comply with the
new standard by February 2006. Motivation
to reduce the arsenic MCL was driven by the
findings of health effects research. Over the
past several years, numerous toxicological and
epidemiological studies have been conducted to
ascertain the health risks associated with low-
level exposure to arsenic ingestion.
Fundamental knowledge of arsenic chemistry
and processes is important when a community
is either looking to install a new treatment
system or modify an old system to comply
with the new arsenic rule. The purpose of this
booklet is to provide engineering firms, utilities,
and communities with information about
treatment technologies for arsenic removal and
design considerations for choosing treatment
technologies.
Any opinions expressed in this document are
those of the author(s) and do not, necessarily,
reflect the official positions and policies of the
EPA. Any mention of products or trade names
does not constitute recommendation for use by
the EPA.
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Importance of Arsenic
The EPA has classified arsenic as a Class A human carcinogen. Ingestion of inorganic arsenic can
result in both cancer and non-cancer health effects (NRC, 1999). Chronic exposure to low arsenic
levels (less than 0.050 mg/L) has been linked to health complications, including cancer of the skin,
kidney, lung, and bladder, as well as skin diseases and neurological and cardiovascular system
conditions (US EPA, 2000). Common sources of contamination include the erosion of natural deposits,
pesticide runoff from orchards, and runoff from glass & electronics production wastes.
Based on the aforementioned research, the US EPA recently reduced the arsenic maximum
contaminant level (MCL) from 0.050 mg/L to 0.010 mg/L (10 [J.g/L). Over 4,000 water systems are
expected to be in violation of the revised MCL for arsenic.
Best Available Treatments for Arsenic Removal
The EPA reviewed potential best available
technologies (BATs) as candidates for arsenic
removal, and in 2001 published a list of the
determined BATs and their removal rates (US EPA,
2001). However, before summarizing those BATs,
it is important to draw attention to certain system
processes that can optimize arsenic removal: pre-
oxidation and pH adjustment.
Pre-Oxidation. In water, arsenic typically
occurs in one of two inorganic forms: the
pentavalent arsenate, As(V), and the trivalent
arsenite, As(III). In the pH range of 4 to 10,
As(V) species are negatively charged, and the
predominant As(III) compound is neutral in
charge. Removal efficiency for As(V) is much
better than removal for As(III). Therefore, in
most cases, reduced inorganic As(III) should be
converted to As(V) to facilitate removal. This step
is often necessary to achieve optimal performance
of the unit processes described below. Chlorine,
permanganate, ozone, and manganese dioxide
media are effective oxidizing agents for this
process. Aeration (i.e. oxygen) is not an effective
method for oxidizing As(III).
In addition, research has shown the point
of oxidant application influences removal
optimization. For instance, arsenic removal is also
optimized, in the case of iron removal, when iron
and arsenic are oxdized at the same time.
pH Adjustment. Removal performance for
many media products is pH dependent. Therefore,
it is sometimes necessary to make adjustments to
pH in order to optimize arsenic removal. Certain
technologies are more impacted than others,
particularly iron-based treatment technologies that
have a higher removal capacity at a lower pH (<8).
The selection of the most appropriate treatment
technology should be based on water quality,
disposal options for residuals, and costs, which will
be discussed in subsequent sections. An overview
of various treatment processes and technologies is
included below as well as the hazardous* and non-
hazardous residual waste (Q).
Ion Exchange. Ion exchange is a physical-
chemical ion exchange process in which ions are
exchanged between a solution phase and solid
resin phase. lonizable groups are exchanged for
ions of similar charge in solution that have a
stronger exchange affinity (i.e. selectivity) for the
resin. In drinking water treatment, this technology
is commonly used for household water softening
(cation exchange) and nitrate removal (anion
exchange). It is important to note that ion exchange
is not effective for As(III) removal.
* California defines a waste as hazardous if the total
concentration of arsenic in the waste water is greater than 500
mg/kg, as per the Total Threshold Limit Concentration (TTLC).
• • • •
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4% Liquid. The liquid residual consists of a
^^ composite of backwash water, regenerant
solution (brine), and rinse water. The liquid
waste water will likely contain high levels of
arsenic that render it a hazardous waste that
must be treated before disposal or sent to a
sanitary sewer.
Activated Alumina (A A). Activated
alumina is a sorption process that uses porous,
granular material with ion exchange properties.
In drinking water treatment, packed-bed AA
adsorption is commonly used for removal of natural
organic matter and fluoride. The removal of As(V)
by adsorption can be accomplished by continuously
passing water under pressure through one or
more beds. AA media can either be regenerated
or disposed and replaced with fresh media.
The efficiency and economics of the system are
contingent upon several factors: pre-oxidation of As
(III) to As(V), constituent(s) interference with the
adsorption process, and the need for pH adjustment
to <6.5.
Regenerated system - liquid. Liquid residual
consists of a composite of backwash water,
caustic regenerant solution, neutralization
(low pH) water, and rinse water. The liquid
waste water will likely contain high levels of
arsenic that render it a hazardous waste that
must be treated before disposal or sent to a
sanitary sewer.
Throw-a-way media system - solid. The
spent solid media contains arsenic and other
constituents removed from the source water.
Exhausted media will likely pass the Toxic
Characteristic Leaching Procedure (TCLP)
test and be classified as non-hazardous.
Reverse Osmosis (RO) Membrane
separation technologies are attractive arsenic
treatment processes for small water systems. They
can address numerous water quality problems
while maintaining simplicity and ease of operation.
RO is a pressure-driven membrane separation
process capable of removing arsenic from water by
means of particle size, dielectric characteristics, and
hydrophilirity/hydrophobicity. RO also effectively
removes other constituents from water, including
organic carbon, salts, dissolved minerals, and color.
This treatment process is relatively insensitive to
pH, although pH adjustment may be required to
protect the membrane from fouling.
A Liquid. Liquid residual consists of membrane
reject water, generally high in total dissolved
solids. The liquid waste water likely contains
high levels of arsenic and other constituents
rejected from the source's water that render
it a hazardous waste that must be treated
before disposal or sent to a sanitary sewer.
Enhanced Lime Softening. Lime softening
is a precipitative process commonly used to remove
calcium and magnesium cations from solution.
To remove arsenic, lime is added to increase the
pH above 10.5 to form magnesium hydroxide. In
this pH range, magnesium hydroxide and As(V) is
removed by co-precipitation. Current lime softening
treatment processes can be enhanced for arsenic
removal.
A Sludge. The semi-liquid residual consists
of sludge from the settling basin and filter
backwash water. The residual will contain
the arsenic and other constituents removed
by the lime softening process and could be a
hazardous waste that must be treated before
disposal or sent to a sanitary sewer.
VALLEY VISTA (AZ) DEMO SITE - KINETICO ACTIVATED ALUMINA
References
National Research Council (NRC), 1999. Arsenic in Drinking
Water. Washington, DC. National Academy Press.
US EPA, 2000. Technologies and Costs for Removal of Arsenic
from Drinking Water, EPA 815R00028, Prepared by Malcolm
Pirnie, Inc. under contract 68C60039 for EPA ORD, December
2000.
US EPA, 2001. National Primary Drinking Water Regulations;
Arsenic and Clarifications to Compliance and New Source
Contaminants Monitoring; Final Rule. Federal Register. Vol. 66.
No. 14. January 22, 2001. Page 6981.
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Treatment Technologies
Enhanced Coagulation/Filtration.
Coagulation/filtration is a precipitative process.
This process can be optimized to remove dissolved
inorganic As(V) from water. The mechanism
involves adsorption and co-precipitation of As(V) to
an aluminum or ferric hydroxide precipitate. As(III)
is not effectively removed because of its overall
neutral charge under natural pH. Because As(III) is
more difficult to remove than As(V), pre-oxidation
is typically necessary. The efficiency and economics
of the system are contingent upon several factors,
including the type and dosage of coagulant, mixing
intensity, and pH. Optimized coagulation-filtration
systems are capable of achieving over 90% removal
of As(V). Although both aluminum and iron
coagulants can remove arsenic, iron coagulants
(ferric chloride or ferric sulfate) are more effective.
A Sludge. The semi-liquid residual consists
of the sludge from the settling basin and
the filter backwash water. The residual will
contain the arsenic and other constituents
removed by the coagulation process and
could be a hazardous waste that must be
treated before disposal or sent to a sanitary
sewer. The solids will likely pass the TCLP
tests.
WHITE ROCK WATER CO. (BOW, NH) DEMO SITE-ADI IRON ADSORPTION
MEDIA SYSTEM
Oxidation/Filtration (Iron Removal).
Oxidation/filtration refers to precipitative processes
that are designed to remove naturally occurring
iron and manganese from water. Most systems
include a contact basin. The process involves
the oxidation of the soluble forms of iron and
manganese to their insoluble forms that are then
removed by filtration. Arsenic can be removed
via two primary mechanisms: adsorption and
coprecipitation. First, soluble iron and As(III) are
oxidized. The As(V) then adsorbs onto the iron
hydroxide precipitates that are ultimately filtered
out of solution. The arsenic removal efficiency is
strongly dependent on the initial iron and arsenic
concentrations. In general, the Fe:As mass ratio
should be at least 20:1, which assumes 1 mg/Fe
removes 50 |jg/As. These conditions customarily
result in an arsenic removal efficiency of 80-90%.
Arsenic removals decrease with increasing pH.
In addition, high levels of natural organic matter
(NOM), orthophosophates, and silicates weaken
arsenic removal efficiency by competing for
sorption sites on iron hydroxide precipitates.
Sludge. The semi-liquid residual consists
of the sludge from the settling basin and
the filter backwash water. The residual will
contain the arsenic and other constituents
removed by the coagulation process and
could be a hazardous waste that must be
treated before disposal or sent to a sanitary
sewer. The solids will likely pass the TCLP
tests.
Non-Treatment Options
Problematic arsenic levels in drinking water can
also be mitigated by using non-treatment options,
including blending, connecting to a neighboring
water source, and drilling a new well. These
options are defined briefly below.
Blending
Combine multiple water sources (e.g. wells)
to produce a water stream with an arsenic
concentration below the MCL.
Connecting to a neighboring water source*
Purchase water that is below the MCL from a nearby
system if an interconnection exists.
Drilling a new well*
Abandon old well, and locate and install a new
source. Drilling a new source may not be the best
option if the aquifer has consistently high levels of
* New source installations may or may not be more
costly than treatment. Assessments must be
made on a case by case basis.
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Training Workshops
Other Available Technologies for Arsenic Removal
Although not originally accepted as best available
technologies (BATs) under the new rule, research
and pilot testing have increased the acceptance
of these technologies as effective methods for
removing arsenic.
lia. There
are currently several adsorption media available:
titanium based media, zirconium based media,
and iron based media. Adsorption on Iron
Based Sorbents (IBS) is an emerging treatment
for arsenic. Studies have shown that this media
has a strong affinity for arsenic under natural
pH conditions, relative to activated Alumina.
This feature allows IBS to treat much higher bed
volumes without the need for pH adjustment,
unless the pH is >8.
A Regenerated system - liquid. Liquid residual
consists of a composite of backwash water,
caustic regenerant solution, and rinse
water. The liquid waste water will likely
contain high levels of arsenic that render it a
hazardous waste that must be treated before
disposal or sent to a sanitary sewer.
Throw-a-way media system - solid. Spent
solid media contains arsenic and other
constituents removed from the source water.
Media will likely pass the TCLP test and be
classified as non-hazardous.
Throw-a-way system - liquid. Liquid
residual consists of the media backwash
water that is usually low in arsenic.
Coagulation-Assisted Micro-
tior Coagulation-assisted micro-filtration
(CMF) uses the same precipitative process
described for oxidation/filtration. The use of
pre-engineered CMF package plants is a realistic
possibility for new installations where water
quality precludes the use of sorption treatment.
The filter membrane retains the As(V) laden
floe formed in the coagulation step and must be
periodically backwashed to dislodge solids and
restore hydraulic capacity. Backwash water is
typically a high-volume, low solids (less than
1.0%) waste stream. The specific amount of solids
will depend on several factors, including coagulant
type, dosage, filter run length, and ambient solids
concentration.
Sludge. A semi-liquid residual consists of
the membrane-filtered liquid waste. The
residual will contain the arsenic and other
constituents removed by the coagulation
process and could be a hazardous waste that
must be treated before disposal or sent to a
sanitary sewer. The solids will likely pass the
TCLP tests.
Point-Of-Use (POU) Treatment. POU
devices can be used to treat arsenic; however, the
Safe Drinking Water Act requires that devices be
owned, controlled, and maintained by the public
water utility or by an agency under contract with
the water utility. POU devices are particularly
attractive for removing contaminants that pose
only an ingestion risk, e.g. arsenic. The primary
advantage of using POU treatment in a small
system is the potential for reduced capital and
treatment costs, relative to centralized treatment,
making it a more economically viable alternative
for smaller systems. However, not all states
accept this treatment process as a suitable
method for removing arsenic. Systems interested
in POU treatment should first check with their
state regarding its acceptance as a small system
compliance technology.
Treatment Technology
Training Workshops
Both the Water Supply and Water Resource Division
(WSWRD) of the National Risk Management Research
Laboratory (NRMRL) and the Office of Ground Water
and Drinking Water (OGWDW) sponsor treatment
technology training workshops. These workshops
focus on training geared toward state drinking water
staff, design engineers, systems owners, and certified
operators and provide participants with in-depth
training on the technologies for removing arsenic
from drinking water.
For more information about past and future
workshops, visit www.epa.gov/ORD/NRMRL/arsenic
or www.epa/gov/OGWDW/arsenic _
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Process Selection
Treatment Technology Selection Considerations
Nearly 97 percent of the water systems affected
by the revised rule are small systems that serve
less than 10,000 people each. In October 2001,
EPA announced an initiative for additional
research and development of cost-effective
technologies to help small community water
systems (<10,000 customers) meet the new arsenic
standard and to provide technical assistance to
operators of small systems in order to reduce
compliance costs. The main considerations when
selecting a treatment technology include water
quality attributes (including pH levels and
initial concentrations of iron, As(III), and As(V)
present in the water), ease of implementation
with current system, residual management, and
cost. The information that follows provides a
simplified overview of the considerations that
should be made when selecting a treatment
technology.
Water Quality Considerations. Arsenic
occurs in natural waters in both inorganic and
organic forms. However, inorganic forms such
as arsenite [As(III)] and arsenate [As(V)] are
predominant in natural waters. The valence
and species of inorganic arsenic are dependent
on the oxidation-reduction conditions and
the pH of the water. Studies have shown that
As(V) is more effectively removed from source
waters than As(III) by iron coagulants, by
precipitation of natural iron, and by adsorptive
media. In addition, As(III) is not removed by
anion exchange resins because of its uncharged
nature. Consequently, if the arsenic in the source
water is predominately As(III), then oxidizing
As(III) to As(V) will result in a higher arsenic
removal efficiency. In summary, research has
shown that arsenic removal capacity is improved
when (1) As(III) is converted to As(V) using a
strong oxidant and (2) increasing levels of iron
concentration are present.
The concentration of iron in source water
can be one of the main drivers in technology
selection, as it is often less expensive than other
arsenic removal technologies. Therefore, given
various regional water quality parameters, the
presence of iron will likely play a prominent
role in technology selection and the treatability
of a given water source. Many of the most
effective arsenic removal processes available
are iron-based treatment technologies such as
chemical coagulation/filtration with iron salts
and adsorptive media with iron-based products.
These processes are particularly effective at
removing arsenic from aqueous systems because
iron surfaces have a strong affinity to adsorb
arsenic. Because of the unique role that iron plays
in facilitating arsenic removal, the level of iron
in the source water is a primary consideration in
the selection of an optimal treatment technology.
Below is a more detailed description of the
range of iron concentrations relative to arsenic
concentrations and how the Fe:As ratio could
influence the treatment technology chosen (see
Figure 1).
• HIGH iron levels ( > 0.3 mg/L). HIGH Fe:As
ratio (>20:1). Iron removal processes can be
used to promote arsenic removal from drinking
water via adsorption and co-precipitation.
Source waters with this ratio are potential
candidates for arsenic removal by iron removal.
(A)
• MODERATE iron levels (> 0.3 mg/L). LOW
Fe:As ratio (< 20:1). If the iron to arsenic ratio
in the source water is less than 20:1, then a
modified treatment process such as coagulation/
filtration with the addition of iron salts should
be considered. (B)
• LOW iron levels (< 0.3 mg/L). Technologies
such as adsorptive media, coagulation/filtration,
and ion exchange are best suited for sites with
relatively low iron levels in their source waters
at less than 300 |ag/L, the secondary MCL for
iron. (C)
This guidance is further illustrated in Figure 1,
which provides selection of an optimal treatment
technology based on initial concentrations of iron
and arsenic in the source water. This process
selection guide is very basic, and the removal
capacities depicted are meant to be used as a
general "rule of thumb." These removal capacities
will only be achieved under optimum adsorptive
and process operational conditions with As(V).
The adjustment of pH is sometimes required
to increase the arsenic removal capacity of
adsorptive media in terms of the percent of
As(III) versus As(V) removed. In general, a pH of
• •••
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Arsenic Treatment
FIGURE 1.
Arsenic treatment - basic
process selection guide.
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Iron - mg/L
less than 7.0 is optimal (but pH 7-8 is acceptable)
for iron-based media adsorption, and a pH of 5.5
is optimal for alumina-based media adsorption.
The pH range for arsenic removal with iron
oxides via coagulation/filtration related processes
is 5.5 to 8. As(V) removal by ion exchange is not
significantly impacted by changes in pH.
Treatment Process and Residuals
Management. The task of navigating through
the alternative arsenic treatment technologies
involves several technical considerations as
well. Some unit processes are more economically
viable under specific circumstances than others.
Optimizing arsenic removal using existing
processes is an ideal option for some utilities.
Water systems can get a general idea of the
treatment technology that would work best for
their systems based on the concentrations of
arsenic and iron in the water, as illustrated in
Figure 1. As with other treatment processes,
arsenic treatment systems produce a residual
for disposal. Arsenic discharge options may be
limited. Handling and disposal methods must be
considered prior to selecting a technology. For
instance, some liquid waste residuals are high
in arsenic and are usually hazardous and need
to either be treated on-site or taken to a disposal
facility. However, most solid wastes associated
with spent media are not hazardous and can be
disposed of in landfills. State regulations vary
from state to state for the discharge of residuals
to water bodies and onto land. It is important
to be aware of not only the federal regulatory
requirements regarding residuals management,
but also applicable state requirements in order to
better evaluate compliance of existing practices
and to plan for needed changes in treatment plant
operations.
Testing and Monitoring. Piloting the
potential mitigation strategies is a normal
procedure to optimize treatment variables and
avoid implementing a strategy that may not
work for unforeseen reasons. Pilot testing for
adsorptive media and other treatment options,
however, is a very time-intensive and expensive
process. For many small systems, piloting may be
performed by the vendor. Piloting, particularly
with the adsorptive media selected, might be
required by the state. Lab and jar tests can also
be used to monitor system performance for iron
removal and coagulation.
Capital and Operating Costs. The EPA
has published several documents on the capital
costs of implementing a treatment system, which
include discussions of equipment, engineering,
installation, operation and maintenance, and
replacement media costs. These costs should
certainly be considered before selecting a
treatment system. (See page 10.)
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Demonstration Sites
Arsenic Treatment Research Demonstration Program
The EPA is conducting full-scale demonstration studies on arsenic removal technologies. Site visits are
encouraged and welcomed to help utilities with treatment selection. (Demonstration site locations and their
respective treatment technologies, water quality measures, and system flow are included in Figure 2 and
Table 1.) The purpose of these demonstration studies is (1) to evaluate the efficiency and effectiveness of the
systems and (2) to determine the cost-effectiveness of the treatment technologies.
For additional information about each site (including costs for equipment, site engineering, installation,
operation, and maintenance) visit our website at www.epa.gov/ORD/NRMRL/arsenic or schedule a visit to a
demonstration site near you.
FIGURE 2.
Map depicting the locations of
the 2003(Round 1)and 2004
(Round 2) demonstration sites
across the country.
TABLE 1. Key data on arsenic treatment demonstration sites.
Demo Site
Technology Demonstrated Water Quality
As(ng/L) Fe(mg/L) Mn (ug/L) pH
Size (flow)
Spring Brook
1 Wales, ME
ATS/A/I Complex2000
37.7
<.025
0.0
8.6
14
White Rock Water Co.
2 Bow, NH
ADI/G2
29.26
0.118
0.1
7.3
70
Water & Sewer District
3 Rollinsford, NH
AdEdge/AD33
36.2
<.030
0.1
7.4
100
Orchard Highland
4 Goffstown, NH
5 Dummerston, VT
6 Felton, DE
7 Queen Anne's County, MD
AdEdge/AD33
ATS/A/I Complex2000
Kinetico/M aerolite
Severn Trent/Sorb33
32.7
30.0
30.0
18.8
<.025
<.025
0.048
0.270
<0.03
ND
<0.02
0.0
6.9
7.9
8.2
7.3
20
7
375
300
g • •••
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1 Demonstration Sites
TABLE 1 (CONT'D). Key data on arsenic treatment demonstration sites.
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
NA =
Demo Site
Brown City, MI
Pentwater, MI
Sandusky, MI
Climax, MN
Sabin, MN
Trailer Park
Sauk Centre, MN
Stewart, MN
Buckeye Lake HS
Newark, OH
Chateau Estates
Springfield, OH
Village of the Pond
Delavan, WI
Greenville, WI
United Water Systems
Arnaudville, LA
Desert Sands MDWCA, NM
Nambe Pueblo, NM
Taos, NM
Oak Manor MUD
Alvin, TX
Webb Con Schools
Bruni, TX
Wellman, TX
Lyman, NE
Three Forks, MT
Lidgerwood, ND
Rimrock, AZ
Valley Vista, AZ
Tohono O'odham Nation, AZ
California Water Service Co.
Lake Isabella, CA
Richmond School District
Susanville, CA
Goldenhills Service District
Tehachapi, CA
STMGID
Reno, NV
Fruitland, ID
Sunset Ranch
Homedale, ID
Oregon Institute of Technology
Klamath Falls, OR
Vale, OR
Okanogan, WA
not available, ND = not detectable
Technology Demonstrated
Severn Trent/Sorb33
Kinetico/Macrolite
US Filter/ Aeralater
Kinetico/Macrolite
Kinetico/Macrolite
Kinetico/Macrolite
AdEdge/AD33
Kinetico/ARM200
AdEdge/AD33
Kinetico/Macrolite
Kinetico/Macrolite
Kinetico/Macrolite
US Filter/GFH
AdEdge/AD33
STS/Sorb33
Severn Trent/Sorb33
AdEdge/AD33
AdEdge/AD33
Kinetico/MetSorb
Kinetico/Macrolite
As (ng/L)
14.2
13.4
15.8
38.7
13.9
25.0
42.0
17.4
24.6
20.1
34.0
33.6/35.9
26.1
33.2
14.1
18.8
55.6
62.0/45.4
20.1
64.3
Kinetico/Treatment Modification 146.2
AdEdge/AD33
Kinetico/AASFSO
AdEdge/AD33
VEETech/HIX
ATS/ A/I Compex 2000
MEI/Zirconium-based media
US Filter/GFH
Kinetico/IX
Kinetico/POU
Kinetic/POEs/POU
Kinetico/IX
Filtronics/Electromedia
50
40.96
33.1
35.4
36.7
14.7
87.9
43.5
NA
32.8
16.7
18.4
Water Quality
Fe (mg/L) Mn (ug/L)
0.127
0.466
1.387
0.546
0.854
3.078
1.344
2.477
1.615
1.499
14.518
.214/.199
0.045
<.030
0.059
0.095
<.025
.019/.004
<.025
<.025
1.325
0.170
<.030
<.025
<.025
0.125
<025
<.030
<.030
NA
<.025
<.025
0.069
NA
NA
0.0
0.1
0.3
0.1
0.0
<0.01
0.0
NA
0.0
0.11/0.10
9.1
0.05
<0.01
0.1
0.008
0.006
0.19
NA
0.544
ND
ND
0..004
0.0
<0.02
<0.01
0.0
0.1
ND
ND
NA
0.1
PH
7.3
6.9
6.9/7.2
7.4
7.3
7.1
7.7
7.6
7.3
7.5
7.3
7.0/7.0
7.8
8.5
9.5
7.8
8.0
8.2/7.7
7.5
7.5
7.2
7.2
7.7
8.2
6.4
7.5
6.9
7.4
7..4
NA
7.9
7.5
8.0
Size (flow)
640
400
210
140
250
20
250
8
150
50
350
292/292
250
145
400
212
100
NA
400
(250)
250
90
37
100
(38)
(7.3)
100
350
250
NA
NA
(525)
(550)
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Research Articles & Additional Reference Materials
Below is a list of several of the reference materials that are available. Additional resources and information
relevant to arsenic treatment (e.g. design manuals, research publications, demonstration fact sheets, decision
trees, etc.) are available on the following websites:
Office of Research and Development, National Risk Management Research Laboratory
www.epa.gov/ORD/NRMRL/arsenic/resource.htm
Office of Ground Water and Drinking Water
www.epa.gov/OGWDW/arsenic.html
Design Manuals/Treatment Handbooks
Technology Selection and System Design USEPA Arsenic Demonstration Program Round 1 (EPA 600-R-05-001)
This report provides source water quality characteristics at each of the 12 demonstration sites and the general
rationale used to select the technologies for demonstration at each site. Information on the design and
operation of each treatment system also is presented. The selection of the adsorptive media and pretreatment
methods depend on a number of factors that affect the system performance, including arsenic concentration
and speciation, pH, and the presence of competing anions, as well as media-specific characteristics such as
costs, media life, and empty-bed contact time (EBCT) requirements.
Design Manual: Removal of Arsenic from Drinking Water by Adsorptive Media (EPA 600-R-03-01 9)
This design manual is an in-depth presentation of the steps required to design and operate a water treatment
plant for removal of excess arsenic from drinking water using the adsorptive media process.
Design Manual: Removal of Arsenic from Drinking Water by Ion Exchange (EPA 600-R-03-080)
This design manual is an in-depth presentation of the steps required to design and operate a water treatment
plant for removing arsenic in the As(V) form from drinking water using the anion exchange process. The
treatment process removes arsenic using a strong base anion exchange resin in either the chloride or
hydroxide form; chloride is the preferred form because salt can be used as the regenerant.
Cost Analysis Reports
Technologies and Costs for Removal of Arsenic from Drinking Water (EPA 815-R-00-028)
Provides an introduction to the arsenic statutory requirements, and defines technolgoy categories. Also
presents the organization of the document. In addition, it presents discussions on available arsenic removal
technologies and associated capital and operation and maintenance costs.
Capital Costs of Arsenic Removal Technologies Demonstration Program Round 1 (EPA 600-R-04-201)
This report provides a brief description of each of the twelve. Round 1 demonstration sites and the respective
technologies being evaluated. Capital costs were organized into three categories— equipment, engineering,
and installation—and then summed to arrive at a total capital investment cost for each system. Operations
and maintenance (O&M) costs associated with the treatment systems were not available at the time of this
publication; however, vendor-supplied estimates on media replacement costs are also provided in this report.
Residuals
Regulations on the Disposal of Arsenic Residuals from Drinking Water Treatment Plants (EPA 600-R-00-025)
With the passage of the various federal statues, restrictions have been placed on the discharge of residuals
to water bodies and onto land. This report summarizes federal regulations and selected state regulations that
govern the management of residuals produced by small drinking water treatment systems removing arsenic
from drinking water.
Treatment of Arsenic Residuals from Drinking Water Removal Processes (EPA 600-R-01-033)
This document provides a short-list of arsenic removal options for residuals produced by ion exchange (Ion
Ex), reverse osmosis (RO), nanofiltration (NF), activated alumina (AA), and iron removal processes. Both
precipitation and adsorption processes were evaluated to remove arsenic.
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Research
Laboratory Study on the Oxidation of Arsenic III to Arsenic V (EPA 600-R-01-021)
A one-year laboratory study was performed to determine the ability of seven oxidants to oxidize As(lll) 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(lll) 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.
Oxidation of As(lll) by Aeration and Storage (EPA 600-R-01-102)
A study of the effects of aeration and storage on the oxidation of arsenic(lll) was undertaken at three utilities
in the U.S. to establish the engineering significance of aeration as a potential pre-treatment method for
arsenic removal.
The following three reports document treatment plant information as well as results of sampling and analysis.
The objective of sampling and analysis for each respective technology was to evaluate the effectiveness of the
water treatment plants to consistently remove arsenic (As) from source water.
Arsenic Removal from Drinking Water by Coagulation/Filtration and Lime Softening Plants (EPA 600-R-00-063)
Arsenic Removal from Drinking Water by Ion Exchange and Activated Alumina Plants (EPA 600-R-00-088)
Arsenic Removal from Drinking Water by Iron Removal Plants (EPA 600-R-00-086)
Regulations
Small System Compliance Technology List for the Surface Water Treatment Rule and Total Coliform Rule
(EPA815-R-98-001)
This listing provides greater detail than earlier listings, on the capabilities, applicability ranges, water quality
concerns, and operational and maintenance requirements for the identified compliance technologies. This
listing also provides, in summary format, issues identified by EPA and its stakeholders in their review of draft
materials.
Small System Compliance Technology List for the Non-Microbial Contaminants Regulated Before 1996
(EPA815-R-98-002)
This document covers both an update of the Surface Water Treatment Rule (SWTR) list and the compliance
technologies identified for the Total Coliform Rule (TCR). These have been grouped into one publication as
they both address microbial contaminants and their indicators in drinking water.
Variance Technology Findings for Contaminants Regulated Before 1996 (EPA 815-R-98-003)
This document describes the variance technology findings for the contaminants regulated before 1996,
including the requirements of the 1996 SDWA; the two-stage screening process that was used to identify
those contaminants that would have technology costs compared against the national-level affordability
criteria; and the derivation of the national-level affordability criteria; the affordable technology
determinations and how treatment costs are compared against the national level affordability criteria.
To order hard copy versions of these reference materials, contact:
National Service Center for Environmental Publications (NSCEP)
US EPA/NSCEP (formerly NCEPI)
P.O. Box 4241 9
Cincinnati, OH 45242-0419
phone: 800.490.9198
fax: 513.489.8695
www.epa.gov/ncepihom/ordering.htm OR http://nepis.epa.gov
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Improving the drinking water in your community.
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Arsenic Removal Treatment Technologies
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National Risk Management
Research Laboratory
Cincinnati OH 45268
EPA/600/S-05/006
November 2005
Recycled/Recyclable
Printed with vegetable-based ink on
paper that contains a minimum of
50% post-consumer fiber content
processed chlorine free
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