EPA/600/R-07/047
June 2007
Arsenic Removal from Drinking Water
by Iron Removal and Adsorptive Media
U.S. EPA Demonstration Project at Stewart, MN
Six-Month Evaluation Report
by
Wendy E. Condit
Abraham S.C. Chen
Lili Wang
Battelle
Columbus, OH 43201-2693
Contract No. 68-C-00-185
Task Order No. 0029
for
Thomas J. Sorg
Task Order Manager
Water Supply and Water Resources Division
National Risk Management Research Laboratory
Cincinnati, Ohio 45268
National Risk Management Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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DISCLAIMER
The work reported in this document was funded by the United States Environmental Protection Agency
(EPA) under Task Order 0029 of Contract 68-C-00-185 to Battelle. It has been subjected to the Agency's
peer and administrative reviews and has been approved for publication as an EPA document. Any
opinions expressed in this paper 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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FOREWORD
The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation's
land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to
formulate and implement actions leading to a compatible balance between human activities and the ability
of natural systems to support and nurture life. To meet this mandate, EPA's research program is
providing data and technical support for solving environmental problems today and building a science
knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect
our health, and prevent or reduce environmental risks in the future.
The National Risk Management Research Laboratory (NRMRL) is the Agency's center for investigation
of technological and management approaches for preventing and reducing risks from pollution that
threaten human health and the environment. The 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; protection of water quality in public water systems; remediation of contaminated
sites, sediments and groundwater; prevention and control of indoor air pollution; and restoration of
ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that
reduce the cost of compliance and to anticipate emerging problems. NRMRL's research provides
solutions to environmental problems by: developing and promoting technologies that protect and improve
the environment; 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 EPA's Office of Research and Development to assist the user
community and to link researchers with their clients.
Sally Gutierrez, Director
National Risk Management Research Laboratory
in
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ABSTRACT
This report documents the activities performed and the results obtained from the first six months of the
EPA arsenic removal technology demonstration project at the Stewart, MN facility. The main objective
of the project is to evaluate the effectiveness of Siemens' Type IIAERALATER® system for iron
removal and AdEdge Technologies' Arsenic Package Unit (APU)-300 system for subsequent arsenic
removal. The effectiveness is evaluated based on the system's ability to remove arsenic to below the new
arsenic maximum contaminant level (MCL) of 10 |og/L. Further, this project also 1) evaluates the
reliability of the treatment system for use at small water facilities, 2) determines the required system
operation and maintenance (O&M) and operator skill levels, 3) characterizes process residuals generated
by the treatment process, and 4) determines the capital and O&M cost of the technology. The types of
data collected include system operation, water quality (both across the treatment train and in the
distribution system), process residuals, and capital and O&M cost.
The 250-gal/min (gpm) treatment system consists of an AERALATER® pretreatment unit and an APU-
300 arsenic removal unit. Used for iron removal, the 11-ft diameter x 26-ft carbon steel AERALATER®
package unit is composed of an aeration tower, a detention tank, and a four-cell gravity filter in one
stacked circular configuration. The effluent from the gravity filter is subsequently polished with AD-33
media, an iron-based adsorptive media developed by Bayer AG for arsenic removal. The APU-300
system consists of two skid-mounted 63-in x 86-in fiberglass vessels configured in parallel. Each vessel
contains 64 ft3 of pelletized AD-33 media supported by gravel underbedding.
The treatment system began routine operation on January 18, 2006. Through the period from January 30
to August 1, 2006, the system treated approximately 10,039,000 gal of water with an average run time of
4.9 hr/day. The average daily demand was 54,822 gal with the peak daily demand of 126,779 gal
occurring on July 12, 2006. Water to the treatment system was supplied by two wells (i.e., Wells No. 3
and 4) each operating at an average flowrate of 194 and 184 gpm, respectively, on an alternating basis.
These reduced flowrates resulted in longer contact times (i.e., 44 to 46 min versus the design value of 34
min) within the AERALATER® detention tank and lower hydraulic loading rates (i.e., 1.9 to 2.0 gpm/ft2
versus the design value of 2.6 gpm/ft2) to the gravity filter. The corresponding flowrates measured
through the APU-300 system also resulted in longer empty bed contact time (EBCT) (i.e., 4.6 to 6.8 min
compared to the design value of 3.8 min) in each vessel. No significant operational or mechanical issues
were experienced during the six-month study period.
The source water contained 35.5 to 56.4 |o,g/L of total arsenic, with As(III) at an average concentration of
34.9 |o,g/L as the predominant species. With NaMnO4 addition prior to aeration (based on February 2,
2006 data), most As(III) was oxidized to As(V), which, along with the pre-existing As(V), was partially
adsorbed onto and co-precipitated with iron solids also formed during this preoxidation step, resulting in
57% As(V) removal. The arsenic-laden iron solids were effectively removed by the gravity filter,
achieving approximately 60% total arsenic and 100% total iron removal. The untreated arsenic was
present mostly as As(V) at 17.2 |og/L, which was subsequently removed by the AD-33 media during the
polishing step. The higher-than-expected amount of As(V) in the gravity filter effluent was thought to
have been caused by the relatively high levels of pH, competing anions (such as phosphorous and silica),
and total organic carbon in source water.
NaMnO4 addition was inadvertently discontinued after one week of operation due to problems with the
chemical feed pump. Total arsenic removal was 34% and the iron removal rate 100% across the gravity
filter. The oxidation of Fe(II) was accomplished through aeration. It was also observed that the oxidation
of As(III) to As(V) was occurring at a rate of over 95% across the gravity filter due to natural biological
processes with only 1.2 (ig/L of As(III) in the filter effluent. The As(V) concentration averaged 24.5
IV
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|o,g/L after the gravity filter. Nitrification was also observed to within the gravity filter, but was not
related to the microbially-mediated As(III) oxidation as noted in this report.
In both cases, the levels of As(V) remained above 10 |o,g/L in the gravity filter effluent, which required
further polishing in the APU-300 unit. Through 10,900 bed volume (BV), the effluent arsenic
concentration averaged 3.1 |o,g/L in the APU-300 effluent.
Comparison of the distribution system sampling results before and after system startup showed a
significant decrease in arsenic concentration from an average of 31.2 to 5.5 (ig/L. However, the average
arsenic concentration in the distribution system at 5.5 (ig/L was higher than the average arsenic
concentration of 0.9 (ig/L following the AD-33 adsorption vessels. Iron and manganese also were
significantly reduced in the distribution system.
AERALATER® backwash was manually initiated by the operator on a weekly basis. The APU-300
system was backwashed manually on two occasions during the six-month study period. Approximately
168,900 gal of wastewater, or 1.7% of the quantity of the treated water, was generated during the first six
months from the AERALATER®. The AERALATER® backwash water contained, on average, 108 mg/L
of total suspended solids (TSS), 46 mg/L of iron, 415 |o,g/L of arsenic, and 68 |o,g/L of manganase with the
majority existing as particulate. The average amount of solids discharged per backwash cycle was
approximately 6.1 Ib, which was composed of 2.6 Ib of elemental iron, 0.004 Ib of elemental manganese,
and 0.02 Ib of elemental arsenic. In addition, 13,472 gal of wastewater were generated by the APU-300
unit or 0.1% of the quantity of treated water.
The capital investment for the system was $367,838, consisting of $273,873 for equipment, $16,520 for
site engineering, and $77,445 for installation, shakedown, and startup. Using the system's rated capacity
of 250 gpm or 360,000 gal/day (gpd), the capital cost was $1,471 per gpm of design capacity ($1.02/gpd).
This calculation did not include the cost of the building to house the treatment system. The O&M cost
consisted primarily of the media replacement cost, which was estimated by the vendor at $41,370 to
change out the AD-33 media. The O&M cost is presented as a function of potential media run length and
will be refined in the Final Evaluation Report once the actual bed volumes to breakthrough become
available.
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CONTENTS
DISCLAIMER ii
FOREWORD iii
ABSTRACT iv
FIGURES vii
TABLES viii
ABBREVIATIONS AND ACRONYMS ix
ACKNOWLEDGMENTS xi
1.0 INTRODUCTION 1
1.1 Background 1
1.2 Treatment Technologies for Arsenic Removal 2
1.3 Project Objectives 2
2.0 CONCLUSIONS 5
3.0 MATERIALS AND METHODS 7
3.1 General Project Approach 7
3.2 System O&M and Cost Data Collection 8
3.3 Sample Collection Procedures and Schedules 8
3.3.1 Source Water 11
3.3.2 Treatment Plant Water 11
3.3.3 Backwash Water 11
3.3.5 Distribution System Water 11
3.3.4 Residual Solids 12
3.4 Sampling Logistics 12
3.4.1 Preparation of Arsenic Speciation Kits 12
3.4.2 Preparation of Sampling Coolers 12
3.4.3 Sample Shipping and Handling 12
3.5 Analytical Procedures 12
4.0 RESULTS AND DISCUSSION 14
4.1 Facility Description 14
4.1.1 Source Water Quality 17
4.1.2 Treated Water Quality and Distribution System 19
4.2 Treatment Process Description 19
4.3 Treatment System Installation 26
4.3.1 System Permitting 26
4.3.2 Building Construction 26
4.3.3 System Installation, Startup, and Shakedown 26
4.4 System Operation 28
4.4.1 AERALATER® Operations 28
4.4.2 APU-300 Operations 29
4.4.3 Backwash Operations 29
4.4.4 Residual Management 31
4.4.5 Reliability and Simplicity of Operation 31
4.4.5.1 Pre- and Post-Treatment Requirements 31
4.4.5.2 System Automation 31
4.4.5.3 Operator Skill Requirements 31
4.4.5.4 Preventative Maintenance Activities 32
VI
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4.4.5.5 Chemical Handling and Inventory Requirements 32
4.5 System Performance 32
4.5.1 Treatment Plant 32
4.5.1.1 Arsenic 32
4.5.1.2 Iron 41
4.5.1.3 Manganese 42
4.5.1.4 pH, DO, and ORP 43
4.5.1.5 Ammonia and Nitrate 43
4.5.1.6 Other Water Quality Parameters 45
4.5.2 Backwash Water Sampling 46
4.5.3 Distribution System Water Sampling 46
4.6 System Costs 46
4.6.1 Capital Cost 46
4.6.2 Operation and Maintenance Cost 49
5.0 REFERENCES 51
APPENDIX A: OPERATIONAL DATA A-l
APPENDIX B: ANALYTICAL DATA TABLES B-l
FIGURES
Figure 3-1. Process Flow Diagram and Sampling Schedule and Locations 10
Figure 4-1. Wellhead 3 at Stewart, MN 14
Figure 4-2. Wellhead 4 at Stewart, MN 15
Figure 4-3. Existing Chemical Addition Equipment at Stewart, MN 15
Figure 4-4. Existing Chemical Addition and Entry Piping with Flow Totalizer and Pressure
Gauge at Stewart, MN 16
Figure 4-5. A 65,000-Gal Water Tower at Stewart, MN 16
Figure 4-6. Schematic of AERALATER® and APU-300 Systems at Stewart, MN 20
Figure 4-7. AERALATER® (left) and APU-300 Systems (right) at Stewart, MN 20
Figure 4-8. Schematic of Type II AERALATER® System (Based on General Arrangement
Drawing Provided by Siemens) 24
Figure 4-9. Schematic of APU-300 System (Based on Process and Instrumentation Diagram
Provided by AdEdge) 25
Figure 4-10. Building with AERLATER® Tower (top), Backwash Sump (bottom left), and
Backwash Water Holding Tanks (bottom right) at Stewart, MN 27
Figure 4-11. Off-Loading and Placement of AERALATER® Unit at Stewart, MN 27
Figure 4-12. Arsenic Speciation Results at Wellhead (IN), After Contact Tank (AC), After
Filtration (AF), and After Vessels A and B Combined (TT) 36
Figure 4-13. Total Arsenic Concentrations Across Treatment Train 38
Figure 4-14. Biogeochemical Cycle of Arsenic (Oremland et al., 2002) 41
Figure 4-15. Total Iron Concentrations across Treatment Train 42
Figure 4-16. Total Manganese Concentrations Across Treatment Train 44
Figure 4-17. Ammonia Removal With Nitrification Across AERALATER® Filter 44
Figure 4-18. Media Replacement and O&M Cost for of Stewart AERALATER® and APU-300
System 50
vn
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TABLES
Table 1-1. Summary of Round 1 and Round 2 Arsenic Removal Demonstration Locations,
Technologies, and Source Water Quality 3
Table 3-1. Predemonstration Study Activities and Completion Dates 7
Table 3-2. Evaluation Objectives and Supporting Data Collection Activities 8
Table 3-3. Sampling Schedule and Analyses 9
Table 4-1. City of Stewart, MN Water Quality Data 18
Table 4-2. Physical and Chemical Properties of AD-33 Media 21
Table 4-3. Design Features of Type II AERALATER® and APU-300 Systems 23
Table 4-4. Treatment System Operational Parameters for Stewart, MN 28
Table 4-5. Summary of Backwash Operations at Stewart, MN 30
Table 4-6. Summary of Arsenic, Iron, and Manganese Results 33
Table 4-7. Summary of Other Water Quality Parameter Results 34
Table 4-8. Backwash Water Sampling Results 47
Table 4-9. Distribution System Sampling Results 47
Table 4-10. Capital Investment Cost for Siemens and AdEdge Treatment System 48
Table 4-11. O&M Cost for City of Stewart, MN Treatment System 50
Vlll
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ABBREVIATIONS AND ACRONYMS
AAL American Analytical Laboratories
Al aluminum
AM adsorptive media
APU arsenic package unit
As arsenic
bgs below ground surface
BV bed volume(s)
Ca calcium
CAOs chemolithoautotrophic arsenite oxidizers
C/F coagulation/filtration
Cl chlorine
CRF capital recovery factor
Cu copper
DBF disinfection by-products
DO dissolved oxygen
DOM dissolved organic matter
EBCT empty bed contact time
EPA U.S. Environmental Protection Agency
F fluoride
Fe iron
FedEx Federal Express
GCSP Greene County Southern Plant
GFH granular ferric hydroxide
gpd gallons per day
gpm gallons per minute
gph gallons per hour
F£AA5 haloacetic acids
F£AO heterotrophic arsenite oxidizers
H2SO4 sulfuric acid
hp horsepower
ICP-MS inductively coupled plasma-mass spectrometry
ID identification
IX ion exchange
kgal kilo gallons
LCR (EPA) Lead and Copper Rule
IX
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MCL maximum contaminant level
MDH Minnesota Department of Health
MDL method detection limit
Mg magnesium
jam micrometer
Mn manganese
mV millivolts
Na sodium
NA not applicable
ND not detected
NS not sampled
NSF NSF International
NTU nephelometric turbidity units
O&M operation and maintenance
OIT Oregon Institute of Technology
ORD Office of Research and Development
ORP oxidation-reduction potential
P&ID process and instrumentation diagram
Pb lead
pCi pico curie
psi pounds per square inch
PLC programmable logic controller
PO4 orthophosphate
POE point-of-entry
POU point-of-use
PVC polyvinyl chloride
QA quality assurance
QA/QC quality assurance/quality control
QAPP Quality Assurance Project Plan
RO reverse osmosis
RPD relative percent difference
Sb antimony
SDWA Safe Drinking Water Act
SiO2 silica
SMCL secondary maximum contaminant level
SO4 sulfate
STS Severn Trent Services
TCLP Toxicity Characteristic Leaching Procedure
TDS total dissolved solids
THM trihalomethanes
TOC total organic carbon
TSS total suspended solids
V vanadium
VOC volatile organic compound
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ACKNOWLEDGMENTS
The authors wish to extend their sincere appreciation to Mr. Michael Richards of the City of Stewart in
Minnesota. Mr. Richards monitored the treatment system and collected samples from the treatment and
distribution systems on a regular schedule throughout this study period. This performance evaluation
would not have been possible without his support and dedication.
XI
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1.0 INTRODUCTION
1.1 Background
The Safe Drinking Water Act (SOWA) mandates that U.S. Environmental Protection Agency (EPA)
identify and regulate drinking water contaminants that may have adverse human health effects and that
are known or anticipated to occur in public water supply systems. In 1975, under the SDWA, EPA
established a maximum contaminant level (MCL) for arsenic at 0.05 mg/L. Amended in 1996, the
SDWA required that EPA develop an arsenic research strategy and publish a proposal to revise the
arsenic MCL by January 2000. On January 18, 2001, EPA finalized the arsenic MCL at 0.01 mg/L (EPA,
2001). In order to clarify the implementation of the original rule, EPA revised the rule on March 25, 2003
to express the MCL as 0.010 mg/L (10 (ig/L) (EPA, 2003). The final rule requires all community and
non-transient, non-community water systems to comply with the new standard by January 23, 2006.
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. As
part of this Arsenic Rule Implementation Research Program, EPA's Office of Research and Development
(ORD) proposed a project to conduct a series of full-scale, on-site demonstrations of arsenic removal
technologies, process modifications, and engineering approaches applicable to small systems. Shortly
thereafter, an announcement was published in the Federal Register requesting water utilities interested in
participating in Round 1 of this EPA-sponsored demonstration program to provide information on their
water systems. In June 2002, EPA selected 17 out of 115 sites to be the host sites for the demonstration
studies.
In September 2002, EPA solicited proposals from engineering firms and vendors for cost-effective arsenic
removal treatment technologies for the 17 host sites. EPA received 70 technical proposals for the 17 host
sites, with each site receiving from one to six proposals. In April 2003, an independent technical panel
reviewed the proposals and provided its recommendations to EPA on the technologies that it determined
were acceptable for the demonstration at each site. Because of funding limitations and other technical
reasons, only 12 of the 17 sites were selected for the demonstration project. Using the information
provided by the review panel, EPA, in cooperation with the host sites and the drinking water programs of
the respective states, selected one technical proposal for each site. As of March 2007, 11 of the 12
systems have been operational and the performance evaluation study for seven systems has been
completed.
In 2003, EPA initiated Round 2 arsenic technology demonstration projects that were partially funded with
Congressional add-on funding to the EPA budget. In June 2003, EPA selected 32 potential demonstration
sites and the community water system at the City of Stewart in Minnesota was one of those selected.
In September 2003, EPA solicited proposals from engineering firms and vendors for arsenic removal
technologies. EPA received 148 technical proposals for the 32 host sites, with each site receiving from
two to eight proposals. In April 2004, another technical panel was convened by EPA to review the
proposals and provide recommendations to EPA with the number of proposals per site ranging from none
(for two sites) to a maximum of four. The final selection of the treatment technology at the sites that
received at least one proposal was made, again, through a joint effort by EPA, the state regulators, and the
host site. Since then, four sites have withdrawn from the demonstration program, reducing the number of
sites to 28. Two technologies were selected for demonstration at the Stewart, MN facility including
Siemens' (formerly known as USFilter) Type IIAERALATER® for iron removal followed by AdEdge
Technologies' AD-33 adsorptive media for arsenic removal.
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1.2 Treatment Technologies for Arsenic Removal
The technologies selected for the Round 1 and Round 2 demonstration host sites include 25 adsorptive
media (AM) systems (the Oregon Institute of Technology [OIT] site has three AM systems), 13 coagula-
tion/filtration (C/F) systems, two ion exchange (IX) systems, and 17 point-of-use (POU) units (including
nine under-the-sink reverse osmosis [RO] units at the Sunset Ranch Development site and eight AM units
at the OIT site), and one system modification. Table 1-1 summarizes the locations, technologies, vendors,
system flowrates, and key source water quality parameters (including As, Fe, and pH) at the 40
demonstration sites. An overview of the technology selection and system design for the 12 Round 1
demonstration sites and the associated capital costs is provided in two EPA reports (Wang et al., 2004;
Chen et al., 2004), which are posted on the EPA website at
http://www.epa.gov/ORD/NRMRL/wswrd/dw/arsenic/index.html.
1.3 Project Objectives
The objective of the arsenic demonstration program is to conduct 40 full-scale arsenic treatment
technology demonstration studies on the removal of arsenic from drinking water supplies. The specific
objectives are to:
• Evaluate the performance of the arsenic removal technologies for use on small
systems.
• Determine the required system operation and maintenance (O&M) and operator skill
levels.
• Characterize process residuals produced by the technologies.
• Determine the capital and O&M cost of the technologies.
This report summarizes the performance of the Siemens' Type IIAERALATER® and AdEdge Arsenic
Package Unit (APU)-300 systems at Stewart, MN during the first six months from February 2 through
August 1, 2006. The types of data collected included system operation, water quality (both across the
treatment train and in the distribution system), residuals, and capital and preliminary O&M cost.
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Table 1-1. Summary of Round 1 and Round 2 Arsenic Removal Demonstration Locations, Technologies, and Source Water Quality
Demonstration
Location
Site Name
Technology (Media)
Vendor
Design
Flowrate
(gpm)
Source Water Quality
As
Oig/L)
Fe
(HS/L)
PH
(S.U.)
Northeast/Ohio
Wales, ME
Bow, NH
Goffstown, NH
Rollinsford,NH
Dummerston, VT
Felton, DE
Stevensville, MD
Houghton, NY(d)
Newark, OH
Springfield, OH
Springbrook Mobile Home Park
White Rock Water Company
Orchard Highlands Subdivision
Rollinsford Water and Sewer District
Charette Mobile Home Park
Town of Felton
Queen Anne's County
Town of Caneadea
Buckeye Lake Head Start Building
Chateau Estates Mobile Home Park
AM (A/I Complex)
AM (G2)
AM (E33)
AM (E33)
AM (A/I Complex)
C/F (Macrolite)
AM (E33)
C/F (Macrolite)
AM (ARM 200)
AM(E33)
ATS
ADI
AdEdge
AdEdge
ATS
Kinetico
STS
Kinetico
Kinetico
AdEdge
14
70W
10
100
22
375
300
550
10
250(e)
38W
39
33
36(a)
30
30W
19W
27W
15W
25W
<25
<25
<25
46
<25
48
270(c)
l,806(c)
l,312(c)
1,61 5W
8.6
7.7
6.9
8.2
7.9
8.2
7.3
7.6
7.6
7.3
Great Lakes/Interior Plains
Brown City, MI
Pentwater, MI
Sandusky, MI
Delavan, WI
Greenville, WI
Climax, MN
Sabin, MN
Sauk Centre, MN
Stewart, MN
Lidgerwood, ND
City of Brown City
Village of Pentwater
City of Sandusky
Vintage on the Ponds
Town of Greenville
City of Climax
City of Sabin
Big Sauk Lake Mobile Home Park
City of Stewart
City of Lidgerwood
AM(E33)
C/F (Macrolite)
C/F (Aeralater)
C/F (Macrolite)
C/F (Macrolite)
C/F (Macrolite)
C/F (Macrolite)
C/F (Macrolite)
C/F&AM (E33)
Process Modification
STS
Kinetico
Siemens
Kinetico
Kinetico
Kinetico
Kinetico
Kinetico
AdEdge
Kinetico
640
400
340(e)
40
375
140
250
20
250
250
14(a)
13(a)
16W
20W
17
39W
34
25W
42W
146W
127(c)
466W
l,387(c)
l,499(c)
7827(c)
546(c)
1,470W
3,078(c)
1,344W
1,325W
7.3
6.9
6.9
7.5
7.3
7.4
7.3
7.1
7.7
7.2
Midwest/Southwest
Amaudville, LA
Alvin, TX
Bruni, TX
Wellman, TX
Anthony, NM
Nambe Pueblo, NM
Taos, NM
Rimrock, AZ
Tohono O'odham
Nation, AZ
Valley Vista, AZ
United Water Systems
Oak Manor Municipal Utility District
Webb Consolidated Independent School
District
City of Wellman
Desert Sands Mutual Domestic Water
Consumers Association
Indian Health Services
Town of Taos
Arizona Water Company
Tohono O'odham Utility Authority
Arizona Water Company
C/F (Macrolite)
AM (E33)
AM (E33)
AM(E33)
AM (E33)
AM (E33)
AM(E33)
AM (E33)
AM (E33)
AM (AAFS50/ARM 200)
Kinetico
STS
AdEdge
AdEdge
STS
AdEdge
STS
AdEdge
AdEdge
Kinetico
770(e)
150
40
100
320
145
450
90W
50
37
35W
19w
56(a)
45
23(a)
33
14
50
32
41
2,068(c)
95
<25
<25
39
<25
59
170
<25
<25
7.0
7.8
8.0
7.7
7.7
8.5
9.5
7.2
8.2
7.8
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Table 1-1. Summary of Arsenic Removal Demonstration Sites (Continued)
Demonstration
Location
Site Name
Technology (Media)
Vendor
Design
Flowrate
(gpm)
Source Water Quality
As
Oig/L)
Fe
(HS/L)
PH
(S.U.)
Far West
Three Forks, MT
Fruitland, ID
Homedale, ID
Okanogan, WA
Klamath Falls, OR
Vale, OR
Reno, NV
Susanville, CA
Lake Isabella, CA
Tehachapi, CA
City of Three Forks
City of Fruitland
Sunset Ranch Development
City of Okanogan
Oregon Institute of Technology
City of Vale
South Truckee Meadows General
Improvement District
Richmond School District
Upper Bodfish Well Cffi-A
Golden Hills Community Service District
C/F (Macrolite)
IX (A300E)
POURO(1)
C/F (Electromedia-I)
POE AM (Adsorbsia/ARM 200/ArsenXnp)
and POU AM (ARM 200)®
IX (Arsenex II)
AM (GFH)
AM (A/I Complex)
AM (HIX)
AM (Isolux)
Kinetico
Kinetico
Kinetico
Filtronics
Kinetico
Kinetico
Siemens
ATS
VEETech
MEI
250
250
75 gpd
750
60/60/30
525
350
12
50
150
64
44
52
18
33
17
39
37W
35
15
<25
<25
134
69w
<25
<25
<25
125
125
<25
7.5
7.4
7.5
8.0
7.9
7.5
7.4
7.5
7.5
6.9
AM = adsorptive media process; C/F = coagulation/filtration; HIX = hybrid ion exchanger; IX = ion exchange process; RO = reverse osmosis
ATS = Aquatic Treatment Systems; MEI = Magnesium Elektron, Inc.; STS = Severn Trent Services
(a) Arsenic existing mostly as As(III).
(b) Design flowrate reduced by 50% due to system reconfiguration from parallel to series operation.
(c) Iron existing mostly as Fe(II).
(d) Replaced Village of Lyman, NE site which withdrew from program in June 2006.
(e) Facilities upgraded systems in Springfield, OH from 150 to 250 gpm, Sandusky, MI from 210 to 340 gpm, and Arnaudville, LA from 385 to 770 gpm.
(f) Including nine residential units.
(g) Including eight under-the-sink units.
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2.0 SUMMARY AND CONCLUSIONS
The Siemens' AERALATER® and AdEdge Technologies' AD-33 APU-300 units were installed and
operated at Stewart, MN since January 18, 2006. Based on the information collected during the first six
months of operation, a summary of the system performance and the preliminary conclusions are provided
as follows:
Performance of the arsenic removal technology:
• The aeration step in the AERALATER® unit was effective in oxidizing soluble iron,
converting 100% of the soluble iron to iron solids. Aeration, however, was only minimally
effective in oxidizing As(III), converting less than 26% (on average) of As(III) to As(V).
• NaMnO4s added as an oxidant prior to aeration, effectively oxidized As(III), converting over
90% of As(III) to As(V). Of the As(V) in the contact section of the AERALATER®, only
57% became attached to the iron solids formed during the preoxidation step, presumably via
adsorption and co-precipitation. The relatively low As(V) removal rate was probably the
result of the relatively elevated pH (i.e., 8.2), competing anions (such as 1.0 mg/L of total
phosphorous [as PO4] and 27.6 mg/L of Si [as SiO2]) and total organic carbon (i.e., 6.7 mg/L)
in raw water.
• Without the addition of NaMnO4, over 95% of As(III) was oxidized to As(V) within the
AERALATER® filter, presumably, via microbial-mediated natural pathways, leaving only 1.2
(ig/L of As(III) in the filter effluent. Nitrification also occurred within the gravity filter and
AD-33 adsorption vessels about 69 days after system startup. Because As(III) oxidation was
observed within 40 days of system startup, it was very likely that oxygen, instead of nitrate,
was the electron acceptor for the microbial-mediated As(III) oxidation process. This
speculation was supported by the observation that over 47% of DO was consumed across the
gravity filter soon after the system startup, with average concentrations decreasing from 5.3
mg/L in the filter influent to 2.8 mg/L in the filter effluent. A separate study conducted at
Battelle using filtered groundwater and filter media obtained from the Greene County
Southern Plant in Beaver Creek, OH that also demonstrated co-occurrence of As(III)
oxidation and nitrification across its sand filters, indicated that nitrification might not be
linked directly to As(III) oxidation and that some arsenite oxidizers most likely were
responsible for the oxidation process observed.
• The As(V) formed in the filter via natural pathways was partially removed by adsorbing to
the pre-formed iron particles in the filter. The average removal rate was 28%, which was
much lower than the 57% As(V) removal rate observed during the preoxidation step. This
observation further confirms that oxidation of iron and arsenic must occur at the same time in
order to achieve good arsenic removal.
• The AERALATER® filter was highly effective in removing particulate matter. Without
NaMnO4 addition, 34% of total arsenic was removed, compared to 60% removed with the use
of NaMnO4 in the preoxidation step. Aeration alone in the AERALATER® system was
sufficient to accomplish complete iron removal. No particulate iron breakthrough was
observed from the AERALATER® filter, suggesting adequate filter backwash frequency.
• Out of the 27.0 (ig/L of total arsenic (on average) in the AERALATER® filter effluent, 23.4
(ig/L was present as As(V) and 1.2 (ig/L as As(III). Arsenic was subsequently removed in
the polishing step by the AD-33 media. After approximately 10,900 BV of throughput, total
arsenic concentrations in the adsorption vessel effluent averaged 3.1 |og/L. Because of the
high As(V) concentrations observed in the filter effluent, further studies are needed to
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determine if preoxidation and even supplemental iron addition would be warranted when
considering the overall O&M cost - that is, the cost associated with preoxidation, iron
addition, and media replacement for a longer AD-33 run length versus that with media
replacement for a shorter AD-33 run length.
• The treatment system has improved water quality in the distribution system. A considerable
decrease was observed in arsenic (from 31.2 to 5.5 ng/L), iron (from 376 to 56 ng/L), and
manganese (from 2.2 to 0.1 |og/L) concentrations in distribution system water before and after
the system startup. However, arsenic concentrations were slightly higher in the distribution
system system than in the treatment plant effluent that may have been the result of
solublization, destablization, and/or desorption of arsenic from pipe surfaces.
Required system operation and maintenance and operator's skill levels:
• Daily operation of the system did not require additional skills beyond those necessary to
operate the existing water supply equipment. The daily demand on the operator was only 10
min/day for routine operations.
• The AERALATER® system did not include automatic backwash triggers. This level of
automation was available from Siemens, but was not selected for this site by the vendor.
Because the system was backwashed only once a week, manual backwash seemed to be
acceptable to the plant operator. The time required was 31 min per backwash event. At sites
requiring more frequent backwash, manual backwash may become an issue.
Characteristics of residuals produced by the technology:
• Residuals produced by the operation of the treatment system include backwash wastewater
from the AERALATER® gravity filter, backwash wastewater from the AD-33 adsorption
vessels, and spent AD-33 media. Because the media was not replaced during the first six
months of system operation, the only residual produced was backwash wastewater from both
units.
• The gravity filter was backwashed on a weekly basis and the AD-33 adsorption vessels were
backwashed with the treated water twice during the six-month study period. The amount of
wastewater produced was equivalent to about 1.8% of the amount of water treated (168,900
or 1.7% from the AERALATER® and 13,472 gal or 0.1% from the APU-300 unit).
• The amount of solids produced per filter backwash cycle was 6.1 Ib that included 2.6 Ib of
elemental iron, 0.004 Ib of elemental manganese, and 0.02 Ib of elemental arsenic.
Cost-effectiveness of the technology:
• The capital investment for the system was $367,838, including $273,873 for equipment,
$16,520 for site engineering, and $77,445 for installation, shakedown, and startup. The
building cost incurred by the City of Stewart was not included in the capital investment cost.
• Using the system's rated capacity of 250 gpm or 360,000 gpd, the capital cost was
$l,471/gpm ($1.02/gpd) of design capacity.
• Although not incurred during the first six months of system operation, the AD-33
media replacement cost would represent the majority of the O&M cost for the system
and was estimated to be $41,370 to change out the AD-33 media.
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3.0 MATERIALS AND METHODS
3.1
General Project Approach
Following the predemonstration activities summarized in Table 3-1, the performance evaluation study of
the treatment system began on February 2, 2006. Table 3-2 summarizes the types of data collected and
considered as part of the technology evaluation process. The overall system performance was evaluated
based on its ability to consistently remove arsenic to below the target MCL of 10 |o,g/L through the
collection of water samples across the treatment train. The reliability of the system was evaluated by
tracking the unscheduled system downtime and frequency and extent of repair and replacement. The
unscheduled downtime and repair information were recorded by the plant operator on a Repair and
Maintenance Log Sheet.
The O&M and operator skill requirements were evaluated based on a combination of quantitative data
and qualitative considerations, including the need for pre- and/or post-treatment, level of system
automation, extent of preventative maintenance activities, frequency of chemical and/or media handling
and inventory, and general knowledge needed for relevant chemical processes and related health and
safety practices. The staffing requirements for the system operation were recorded on an Operator Labor
Hour Log Sheet.
The quantity of aqueous and solid residuals generated was estimated by tracking the volume of backwash
water produced during each backwash cycle. Backwash water was sampled and analyzed for chemical
characteristics.
The cost of the system was evaluated based on the capital cost per gal/min (gpm) (or gal/day [gpd]) of
design capacity and the O&M cost per 1,000 gal of water treated. This task required tracking the capital
cost for equipment, engineering, and installation, as well as the O&M cost for media replacement and
disposal, chemical supply, electricity usage, and labor.
Table 3-1. Predemonstration Study Activities and Completion Dates
Activity
Introductory Meeting Held
Draft Letter of Understanding Issued
Final Letter of Understanding Issued
Request for Quotation Issued to Vendor
Vendor Quotation Received
Purchase Order Established
Letter Report Issued
Engineering Package Submitted to MDH
System Permit Granted by MDH
Building Construction Permit Granted
Building Construction Began
APU-300 Unit Shipped/Arrived
AERALATER® Shipped/ Arrived
System Installation/Shakedown Completed
Study Plan Issued
Performance Evaluation Began
Building Construction Completed
Date
08/30/04
11/18/04
12/10/04
01/21/05
03/15/05
03/29/05
03/09/05
03/21/05
06/20/05
06/13/05
07/01/05
09/06/05
09/16/05
01/18/06
01/24/06
02/02/06
02/09/06
MDH = Minnesota Department of Health
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Table 3-2. Evaluation Objectives and Supporting Data Collection Activities
Evaluation Objective
Performance
Reliability
System O&M and Operator
Skill Requirements
Residual Management
Cost-Effectiveness
Data Collection
-Ability to consistently meet 10 ng/L of arsenic in treated water
-Unscheduled system downtime
-Frequency and extent of repairs including a description of problems,
materials and supplies needed, and associated labor and cost
-Pre- and post-treatment requirements
-Level of automation for system operation and data collection
-Staffing requirements including number of operators and laborers
-Task analysis of preventative maintenance including number, frequency,
and complexity of tasks
-Chemical handling and inventory requirements
-General knowledge needed for relevant chemical processes and health and
safety practices
-Quantity and characteristics of aqueous and solid residuals generated by
system operation
-Capital cost for equipment, engineering, and installation
-O&M cost for chemical usage, electricity consumption, and labor
3.2
System O&M and Cost Data Collection
The plant operator performed daily, weekly, and monthly system O&M and data collection according to
instructions provided by the vendor and Battelle. On a daily basis, the plant operator recorded system
operational data, such as pressure, flowrate, totalizer, and hour meter readings on a Daily System
Operation Log Sheet and conducted visual inspections to ensure normal system operations. If any
problem occurred, the plant operator contacted the Battelle Study Lead, who determined if the vendor
should be contacted for troubleshooting. The plant operator recorded all relevant information, including
the problem, course of actions taken, materials and supplies used, and associated cost and labor, on a
Repair and Maintenance Log Sheet. On a weekly basis, the plant operator measured several water quality
parameters on-site, including temperature, pH, dissolved oxygen (DO), oxidation-reduction potential
(ORP), and residual chlorine, and recorded the data on a Weekly On-Site Water Quality Parameters Log
Sheet. Weekly backwash data also were recorded on a Backwash Log Sheet.
The capital cost for the arsenic removal system consisted of the cost for equipment, site engineering, and
system installation. The O&M cost consisted of the cost for media replacement, electricity consumption,
and labor. Electricity consumption was determined from utility bills. Labor for various activities, such as
routine system O&M, troubleshooting and repairs, and demonstration-related work, were tracked using an
Operator Labor Hour Log Sheet. The routine system O&M included activities, such as completing field
logs, ordering supplies, performing system inspections, and others as recommended by the vendor. The
labor for demonstration-related work, including activities such as performing field measurements,
collecting and shipping samples, and communicating with the Battelle Study Lead and the vendor, was
recorded, but not used for the cost analysis.
3.3
Sample Collection Procedures and Schedules
To evaluate system performance, samples were collected at the wellhead, across the treatment plant, at the
AERALATER® backwash discharge sump, and from the distribution system. The sampling schedules
and analytes measured during each sampling event are listed in Table 3-3. In addition, Figure 3-1
presents a flow diagram of the treatment system along with the analytes and schedules at each sampling
location. Specific sampling requirements for analytical methods, sample volumes, containers,
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Table 3-3. Sampling Schedule and Analyses
Sample
Type
Source
Water
Treatment
Plant Water
Backwash
Water
Distribution
Water
Residual
Solids
Sample
Location'3*
At Wellhead (IN)
At Wellhead (IN),
after Contact (AC),
after Gravity Filter
(AF),
after Vessel A
(TA),
after Vessel B (TO)
At Wellhead (IN),
after Contact (AC),
after Gravity Filter
(AF),
At Vessels A and B
Combined (TT)
At Backwash
Discharge Sump
Three Non-LCR
Residences
At Backwash
Water Discharge
Sump
No. of
Samples
1
5
4
2
3
2
Frequency
Once
(during
initial site
visit)
Weekly
Monthly
Monthly
Monthly
Twice
Analyte
On-site: pH, temperature,
DO, and ORP
Off-site: As (total,
soluble, paniculate),
As(III), As(V),
Fe (total and soluble),
Mn (total and soluble),
V (total and soluble),
U (total and soluble),
Na, Ca, Mg, Cl, F, NO3,
NO2, NH3, SO4, SiO2,
PO4,Ra-226,Ra-228,
alkalinity, turbidity,
TDS, andTOC
On-site: pH, temperature,
DO, and ORP
Off-site: As (total),
Fe (total), Mn (total),
P (total), SiO2, alkalinity,
and turbidity
Same as weekly analytes
shown above plus the
following:
Off-site: As (soluble and
paniculate), As(III),
As(V), Fe (soluble),
Mn (soluble), Ca, Mg, F,
NO3, NH3, SO4, SiO2,
andTOC
As (total and soluble),
Fe (total and soluble),
Mn (total and soluble),
pH, TDS, andTSS
Total As, Fe, Mn, Cu,
and Pb, pH, and
alkalinity
TCLP metals and total
Al, As, Ca, Cd, Cu, Fe,
Mg, Mn, Ni, P, Pb, Si,
andZn
Sampling
Date
08/30/04
02/14/06, 02/21/06,
03/06/06, 03/14/06,
03/21/06,04/04/06,
04/11/06,04/18/06,
05/02/06, 05/09/06,
05/16/06, 05/30/06,
06/06/06, 06/13/06,
06/27/06, 07/05/06,
07/11/06,07/25/06,
08/01/06
02/02/06, 02/27/06,
03/28/06(c),
04/25/06, 05/24/06,
06/20/06, 07/18/06
03/01/06, 03/22/06,
04/12/06,05/31/06,
06/28/06, 07/26/06
Baseline sampling(c):
02/16/05, 03/16/05,
04/13/05, 05/18/05
Monthly sampling:
02/22/06, 03/21/06,
04/18/06, 05/16/06,
06/13/06,07/11/06
TBD
(a) Abbreviation corresponding to sample location in Figure 3 -1.
(b) Sampling events performed before system startup.
(c) Sampling events before 04/25/06 taken from TA or TO tap due to absence of combined effluent sample tap.
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Monthly
pHW, temperature^, DOW
As (total and soluble), As (III),
As (V), Fe (total and soluble), __
Mn (total and soluble), Ca, Mg, F,
NO3, SO4, SiO2, P (total), NH3,
TOC, turbidity, alkalinity
INFLUENT
Stewart, MN
AERALATER®/AD-33® Technology
Design Flow: 250 gpm
1
KMnO4
AERATOR
HW, temperature^, DOW
As (total and soluble), As (III),
As (V), Fe (total and soluble),
Mn (total and soluble), Ca, Mg,
F, NO3, SO4, SiO2, P (total), NH3,
TOC, turbidity, alkalinity
HW, temperature^, DO
AF ) After Gravity Filter
[TAJ After Vessel A
TB ) After VesselB
IT ) After Vessels A & B Combined
, BW \ Backwash Sampling Location
SS } Sludge Sampling Location
T^* { f~\ I * WLC1331U111
KMnO, „ . , ..
4 I Oxidation
Un
Potassium Permanganate
INFLUENT I Unit Process
Process Flow
Backwash Flow
pH(a), temperature^),
DO
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preservation, and holding times are presented in Table 4-1 of the EPA-endorsed Quality Assurance
Project Plan (QAPP) (Battelle, 2004). The procedure for arsenic speciation is described in Appendix A of
the QAPP.
3.3.1 Source Water. During the initial visit to the site, one set of source water samples was
collected and speciated using an arsenic speciation kit (see Section 3.4.1). The sample tap was flushed for
several minutes before sampling; special care was taken to avoid agitation, which might cause unwanted
oxidation. Analytes for the source water samples are listed in Table 3-3.
3.3.2 Treatment Plant Water. During the system performance evaluation study, the plant
operator collected samples weekly, on a four-week cycle, for on- and off-site analyses. For the first week
of each four-week cycle, samples taken at the wellhead (IN), after the contact tank (AC), after
AERALATOR® gravity filter (AF), and after APU-300 Vessels A and B combined (TT), were speciated
on-site and analyzed for the analytes listed in Table 3-3 for monthly treatment plant water. For the next
three weeks, samples were collected at IN, AC, AF, and after APU-300 Tanks A (TA) and B (TB) and
analyzed for the analytes listed in Table 3-3 for the weekly treatment plant water.
3.3.3 Backwash Water. AERALATER® backwash water samples were collected monthly by the
plant operator. Because of lack of a sampling tap on the backwash water discharge line, grab samples
were taken directly from the backwash water discharge sump during each of the six monthly backwash
events. One aliquot was collected as is and the other filtered on-site with 0.45-(im disc filters. Analytes
for the backwash samples are listed in Table 3-3. Arsenic speciation was not performed for the backwash
water samples.
During the second half of the one-year study period, composite samples of backwash water will be
collected. A clean, 32-gal plastic container will be filled from the discharge sump and the contents
thoroughly mixed using a mixing rod. One aliquot will be collected as is and the other filtered on-site
with 0.45-(im disc filters. The samples will be analyzed for the same set of analytes performed during the
first six-month study period.
The APU-300 system was backwashed manually twice during the first six-month study period; however,
no samples were collected. One set of composite backwash water samples will be collected during the
next six month period. These samples will be collected from a sampling device similar to the one used
for AERALATER® filter backwash. The only difference will be that a side stream of backwash water
will be directed from a sample tab on the APU-300 backwash water discharge line to the plastic container.
Filtered and unfiltered samples will be analyzed for the same set of analytes listed under backwash water.
3.3.4 Distribution System Water. Samples were collected from the distribution system to
determine the impact of the arsenic treatment system on the water chemistry in the distribution system,
specifically, the arsenic, lead, and copper levels. Prior to the system startup from February to May 2005,
four sets of baseline distribution water samples were collected from three residences within the
distribution system. Following the system startup, distribution system sampling continued on a monthly
basis at the same three locations.
The homeowners collected samples following an instruction sheet developed according to the Lead and
Copper Monitoring and Reporting Guidance for Public Water Systems (EPA, 2002). The dates and times
of last water usage before sampling and sample collection were recorded for calculation of the stagnation
time. All samples were collected from a cold-water faucet that had not been used for at least 6 hr to
ensure that stagnant water was sampled.
11
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3.3.5 Residual Solids. Residual solids produced by the treatment process included backwash
solids and spent media, which were not collected during the initial six months of this demonstration.
3.4 Sampling Logistics
3.4.1 Preparation of Arsenic Speciation Kits. The arsenic field speciation method uses an anion
exchange resin column to separate the soluble arsenic species, As(V) and As(III) (Edwards et al., 1998).
Resin columns were prepared in batches at Battelle laboratories according to the procedures detailed in
Appendix A of the EPA-endorsed QAPP (Battelle, 2004).
3.4.2 Preparation of Sample Coolers. For each sampling event, a sample cooler was prepared
with the appropriate number and type of sample bottles, disc filters, and/or speciation kits. All sample
bottles were new and contained appropriate preservatives. Each sample bottle was affixed with a pre-
printed, colored-coded label consisting of the sample identification (ID), date and time of sample
collection, collector's name, site location, sample destination, analysis required, and preservative. The
sample ID consisted of a two-letter code for the specific water facility, sampling date, a two-letter code
for a specific sampling location, and a one-letter code designating the arsenic speciation bottle (if
necessary). The sampling locations at the treatment plant were color-coded for easy identification. The
labeled bottles for each sampling locations were placed in separate Ziplock™ bags and packed in the
cooler.
In addition, all sampling- and shipping-related materials, such as disposable gloves, sampling instructions,
chain-of-custody forms, prepaid/addressed FedEx air bills, and bubble wrap, were included. The chain-of-
custody forms and air bills were complete except for the operator's signature and the sample dates and
times. After preparation, the sample cooler was sent to the site via FedEx for the following week's
sampling event.
3.4.3 Sample Shipping and Handling. After sample collection, samples for off-site analyses were
packed carefully in the original coolers with wet ice and shipped to Battelle. Upon receipt, the sample
custodian verified that all samples indicated on the chain-of-custody forms were included and intact.
Sample IDs were checked against the chain-of-custody forms, and the samples were logged into the
laboratory sample receipt log. Discrepancies noted by the sample custodian were addressed with the plant
operator by the Battelle Study Lead.
Samples for metal analyses were stored and analyzed at Battelle's inductively coupled plasma-mass
spectrometry (ICP-MS) laboratory. Samples for other water quality parameters were packed in separate
coolers and picked up by couriers from American Analytical Laboratories (AAL) in Columbus, Ohio, and
TCCI Laboratories in New Lexington, Ohio, both of which were under contract with Battelle for this
demonstration study. The chain-of-custody forms remained with the samples from the time of
preparation through analysis and final disposition. All samples were archived by the appropriate
laboratories for the respective duration of the required hold time and disposed of properly thereafter.
3.5 Analytical Procedures
The analytical procedures described in Section 4.0 of the EPA-endorsed QAPP (Battelle, 2004) were
followed by Battelle ICP-MS, AAL, and TCCI Laboratories. Laboratory quality assurance/quality control
(QA/QC) of all methods followed the prescribed guidelines. Data quality in terms of precision, accuracy,
method detection limits (MDL), and completeness met the criteria established in the QAPP (i.e., relative
percent difference [RPD] of 20%, percent recovery of 80 to 120%, and completeness of 80%). The quality
assurance (QA) data associated with each analyte will be presented and evaluated in a QA/QC Summary
Report to be prepared under separate cover upon completion of the Arsenic Demonstration Project.
12
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Field measurements of pH, temperature, DO, and ORP were conducted by the plant operator using a
VWR Symphony SP90M5 handheld multimeter, which was calibrated for pH and DO prior to use
following the procedures provided in the user's manual. The ORP probe also was checked for accuracy
by measuring the ORP of a standard solution and comparing it to the expected value. The plant operator
collected a water sample in a clean, plastic beaker and placed the SP90M5 probe in the beaker until a
stable value was obtained.
13
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4.0 RESULTS AND DISCUSSION
4.1
Facility Description
The water treatment system at Stewart, MN, supplies drinking water to approximately 600 community
members. The water source is groundwater from two wells (Wells No. 3 and 4). Wellheads 3 and 4 are
shown in Figures 4-1 and 4-2, respectively. The static water level of the wells ranges from 20 to 30 ft
below ground surface (bgs). Each well is 8-in in diameter and extends to a depth of approximately 370 ft
bgs. Well No. 3 has a 50-ft screen length and is equipped with a 20-horsepower (hp) submersible pump
with a capacity of approximately 350 gpm. Well No. 4 has a 52-ft screen length and a 15-hp submersible
pump with a capacity of approximately 275 gpm. The average daily demand is 48,600 gpd and the peak
daily demand is 125,300 gpd. Use of these two wells is alternated automatically based on the water tower
level. Typically, each well runs for about 12,000 to 15,000 gal per cycle.
The pre-existing treatment consisted of chlorination, fluoridation, and polyphosphate addition.
Chlorination was accomplished with a gas chlorine feed system to provide chlorine residuals in the
distribution system. The target residual level was 1.1 mg/L for total chlorine (as C12). The water also was
fluoridated to a target level of 1.3 mg/L. Blended polyphosphates were added for iron sequestration and
corrosion control. Figure 4-3 shows the chemical feed pumps and associated tanks within the pump
house. Figure 4-4 shows the entry piping from Wells No. 3 and 4 and the tubing from the chemical feed
pumps. The pre-existing equipment shown in Figures 4-3 and 4-4 was replaced with new equipment of
similar sizes as part of the pre- and post-treatment, as described in Section 4.2. The treated water is stored
in a nearby 65,000-gal water tower shown in Figure 4-5.
Figure 4-1. Wellhead 3 at Stewart, MN (near orange flag in center of photo)
14
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Figure 4-2. Wellhead 4 at Stewart, MN (in front of small brown shed)
Figure 4-3. Existing Chemical Addition Equipment at Stewart, MN
15
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Figure 4-4. Existing Chemical Addition and Entry Piping with Flow Totalizer and
Pressure Gauge at Stewart, MN
Figure 4-5. A 65,000-Gal Water Tower at Stewart, MN
16
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4.1.1 Source Water Quality. Source water samples were collected from Well No. 3 on August
30, 2004, by Battelle for detailed water quality characterization; the analytes of interest are presented in
Table 3-3. In addition, pH, temperature, DO, and ORP were measured on-site using a VWR Symphony
SP90MS handheld multimeter. The source water also was filtered for soluble arsenic, iron, manganese,
uranium, and vanadium and speciated for As(III) and As(V) using the field speciation method modified
from Edwards et al. (1998) by Battelle. The analytical results from the source water sampling event are
presented in Table 4-1 and compared to historic data taken by the facility.
The proposed treatment train for the City of Stewart included oxidation with potassium permanganate
(KMnO4), iron removal using gravity filtration, and arsenic adsorption with AD-33 media. Several
factors were anticipated to play a role in the pretreatment process for iron removal, including natural iron
concentration, pH, turbidity, natural organic matter, ammonia, anions, and cations. Factors that may
affect arsenic removal via adsorption include arsenic concentration, arsenic speciation, pH, and other
competing anions.
Arsenic. Total arsenic concentrations in source water ranged from 39.0 to 41.7 |o,g/L. Based on August
30, 2004 sampling results from Well No. 3, out of 41.7 |o,g/L of total arsenic, 31.9 |o,g/L existed as As(III),
1.0 ny/L as As(V), and 8.8 |o,g/L as particulate As. Therefore, As(III) was the predominating species in
groundwater. The proposed treatment process was to use KMnO4, as originally designed, but switched to
NaMnO4 just before the system startup by the City, to oxidize As(III) to As(V) prior to iron removal and
AD-33 adsorption. Oxidant addition was discontinued after the discovery of a naturally occurring
oxidation process developed within the AERALATER® filter (see detailed discussion in Section 4.5.1.1).
Upon oxidation, As(V) was removed via adsorption onto and/or co-precipitation with iron solids during
the iron removal pretreatment step. The remaining As(V) was then removed via adsorption onto the AD-
33 media.
Iron and Manganese. In general, adsorptive media technologies are best suited to source waters with
relatively low iron levels (i.e., less than 300 |o,g/L, which is the secondary maximum contaminant level
[SMCL] for iron). Above 300 |o,g/L, taste, odor, and color problems can occur in treated water, along
with an increased potential for fouling of the adsorption system. The proposed treatment process at
Stewart, MN relied on aeration and gravity filtration to remove elevated levels of iron in source water.
This iron removal process also resulted in the removal of some As(V) in the water. Iron concentrations in
source water ranged from 1,344 to 1,400 |o,g/L, which existed almost entirely as soluble iron. Total
manganese in source water ranged from 24 to 27 |o,g/L, which was below the SMCL of 50 |og/L.
pH. pH values of source water ranged from 7.7 to 7.8, which were near the upper end of the target range
of 6.0 to 8.0 for optimal arsenic adsorption onto the AD-33 media.
TOC and Ammonia. The source water contained elevated levels of total organic carbon (TOC) (ranging
from 6.8 to 7.2 mg/L) and ammonia (at 1.7 mg/L). To avoid the formation of disinfection by-products
(DBFs) and high chlorine consumption, the treatment process used NaMnO4, instead of chlorine, for
As(III) oxidation. However, as mentioned above, oxidant addition was later discontinued because iron
removal was accomplished through aeration and As(III) oxidation attained via a naturally occurring
process.
Competing Anions. The adsorption of arsenic onto iron solids and AD-33 media also may be influenced
by the presence of competing anions such as silica, sulfate, and phosphate. At the Stewart, MN site, silica
levels ranged from 24.0 to 26.6 mg/L (as SiO2) and sulfate levels ranged from <5 to 7.4 mg/L. These
concentrations were low enough not to pose a significant problem for effective arsenic adsorption. The
orthophosphate level was 0.02 mg/L; however, as discussed in Section 4.5.1.6, total phosphorous level
17
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Table 4-1. City of Stewart, MN Water Quality Data
Parameter
Sampling Date
pH
DO
ORP
Alkalinity (as CaCO3)
Hardness (as CaCO3)
Turbidity
TDS
TOC
Total N (Nitrate + Nitrite)
Nitrate (as N)
Nitrite (as N)
Ammonia (as N)
Chloride
Fluoride
Sulfate
Silica (as SiO2)
Orthophosphate (as PO4)
As (total)
As (soluble)
As (paniculate)
As(III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
U (total)
U (soluble)
V (total)
V (soluble)
Na (total)
Ca (total)
Mg (total)
Ra-226
Ra-228
Gross-Alpha
Gross-Beta
Radon
Unit
S.U.
mg/L
mV
mg/L(a)
mg/L(a)
NTU
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
mg/L
mg/L
mg/L
pCi/L
pCi/L
pCi/L
pCi/L
pCi/L
Concentration
Utility
Raw Water
Data(a)
Not Specified
7.8
NS
NS
415
230
NS
NS
6.8
NS
NS
NS
NS
6.5
NS
7.4
24.0
0.02
39.0
NS
NS
39
<0.1
1,400
NS
24.0
NS
NS
NS
NS
NS
87
46
28
NS
NS
NS
NS
NS
Battelle
Well NO. 3
Raw Water
Data
08/30/04
7.7
2.2
-86
424
246
7
462
7.2
NS
O.04
O.01
1.7
7.2
0.4
<5.0
26.6
<0.1
41.7
32.9
8.8
31.9
1.0
1,344
1,359
27.0
28.0
<0.1
<0.1
<0.1
<0.1
87
56
26
<1.0
<1.0
NS
NS
NS
MDH
Treated Water
Data*'
10/16/01-10/18/04
7.7-7.8
NS
NS
410-420
<240
-------
was elevated at 0.90 mg/L (as PO4) and could compete with arsenic for available adsorption sites onto
iron solids and AD-33 media.
Other Water Quality Parameters. Alkalinity, hardness, sodium, and total dissolved solids (TDS) levels
in source water were all elevated. Alkalinity values ranged from 415 to 424 mg/L (as CaCO3); hardness
values ranged from 230 to 246 mg/L (as CaCO3); and sodium and TDS concentrations (in August 30,
2004 sample) were 87 and 462 mg/L. Other water quality parameters, including nitrate, nitrite, chloride,
fluoride, uranium, vanadium, were below their respective detection limits or SMCLs. Radium was
measured at less than the detection limit of < 1.0 pCi/L.
4.1.2 Treated Water Quality and Distribution System. Historic water samples were taken from
both Wells No. 3 and 4, but after chlorination, fluoridation, and polyphosphate addition; therefore, the
analytical results obtained from the Minnesota Department of Health (MDH) are included in Table 4-1 as
treated water data. These water samples were collected from residences, businesses (stores), city hall, and
the treatment plant from October 16, 2001, through October 18, 2004.
Historic As levels detected within the distribution system ranged from 34.0 to 43.0 (ig/L; iron levels
ranged from 1,200 to 1,500 (ig/L, and manganese levels ranged from 22 to 25 (ig/L. These concentrations
were similar to those measured in raw water. Results of other water quality parameters measured
historically also were very close to those found in the raw water samples collected by the facility and
Battelle.
The distribution system at Stewart, MN is supplied only by Wells No. 3 and 4. Water from Wells No. 3
and 4 is blended within the distribution system and the 65,000-gal water tower. Based on the distribution
system blueprint, the mains for the water distribution system are primarily constructed of 6-in to 8-in cast
iron. Other connections within the distribution system include 3/t-in to 2-in galvanized iron, 2-in copper,
and 2-in polyvinyl chloride (PVC) piping. Three locations were selected for both baseline and
distribution system sampling after system startup. The locations were selected as part of the City's
historic sampling network for the Lead and Copper Rule. Compliance samples also include quarterly
sampling for arsenic, coliform, total chlorine residual, and fluoride and annual sampling for nitrate,
volatile organic compounds (VOCs), trihalomethanes (THMs), haloacetic acids (HAA5), turbidity, TOC,
alkalinity, and radionuclides.
4.2 Treatment Process Description
The 250-gpm treatment system at Stewart, MN consists of pre-treatment for iron removal followed by
adsorption with AD-33 media for arsenic removal (Figure 4-6). This section provides a detailed
description of the Siemens' Type II AERALATER® system for iron removal and AdEdge's APU-300
system for arsenic adsorption.
Due to elevated iron levels in source water, the adsorption system is preceded by a Siemens' Type II
AERALATER® system for iron (and some arsenic) removal via oxidation and filtration. Figure 4-7
shows the 11-ft diameter AERALATER® system, which is a packaged unit for oxidation, detention, and
gravity filtration. The AERALATER® system includes an aeration chamber, a detention tank, and four
filter cells. The treatment processes involved permanganate oxidation (with the oxidant added at inlet
piping to the AERALATER® system), aeration, adsorption/co-precipitation of As(V) onto/with iron
solids, and gravity filtration with anthracite and silica sand. The filtration media are approved for use in
drinking water applications under NSF International (NSF) Standard 61. More details on the Siemens'
Type II AERALATER® system are provided below.
19
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Explanation
Liquid Process Line
Pumped
to Sewer
PROCFLOWQ.1 CDR
Figure 4-6. Schematic of AERALATER® and APU-300 Systems at Stewart, MN
Figure 4-7. AERALATER® (left) and APU-300 Systems (right) at Stewart, MN
20
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The soluble As(V) that remains in the treated water after the AERALATER® system is further treated by
the AdEdge APU-300 system. Designed for arsenic removal for small systems in the flow range of 10 to
300 gpm, the APU series is a fixed-bed adsorption system. As groundwater is pumped through fixed-bed
pressure vessels, soluble arsenic is adsorbed onto the media, thus reducing the soluble arsenic
concentration to below the 10 (ig/L MCL. The APU-300 adsorption system consists of two 63-in
diameter, 86-in tall vessels configured in parallel (see Figure 4-7). Each vessel contains 64 ft3 of
pelletized Bay oxide® E33 media (branded as AD-33 by AdEdge). This iron-based adsorptive media was
developed by Bayer AG for the removal of arsenic from drinking water supplies. Table 4-2 presents the
physical and chemical properties of the media. The AD-33 media is delivered in a dry crystalline form
and listed by NSF under Standard 61 for use in drinking water applications. AD-33 is available in both
granular and pelletized forms. The pelletized media used at the Stewart, MN site is 25% denser than the
granular media (35 vs. 28 lb/ft3). Both media are reported by the vendor to have similar arsenic
adsorption capacities on a per pound basis. After reaching its capacity, the spent media is removed and
disposed of as nonhazardous waste after passing EPA's toxicity characteristic leaching procedure (TCLP)
test. The media life depends upon the arsenic concentration, pH, and concentrations of interfering ions in
the influent water.
Table 4-2. Physical and Chemical Properties of AD-33 Media
Parameter
Value
Physical Properties
Matrix
Physical form
Color
Bulk Density (lb/ft3)
Bulk Density (g/cm3)
BET Area (m2/g)(a)
Attrition (%)(a)
Moisture Content (%)
Particle size distribution
(U.S. Standard Mesh)
Crystal Size (A)(a)
Crystal Phase(a)
Iron oxide/Hydroxide
Dry pelletized media
Amber/rust
35
0.56
142
0.3
5% by weight
14 x 18
(1.0 to 1.4mm)
70
a-FeOOH
Ch emical An afysis
Constituents
FeOOH
CaO
MgO
MnO
S03
Na2O
TiO2
Si02
A12O3
P2O5
Cl
Weight (%)
90.1
0.27
1.00
0.11
0.13
0.12
0.11
0.06
0.05
0.02
0.01
Data Source: Bayer AG
(a) For dry granular media
21
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Table 4-3 presents design features of the treatment system at Stewart, MN. The major process
components of the treatment system are described as follows:
• Intake. Raw water is pumped from Wells No. 3 and 4, alternately, and fed into the entry
piping to the Siemens Type II AERALATER® unit. The well pumps are turned on and off
based on the low and high level settings of 23 and 27 ft of H2O, respectively, in the water
tower.
• Oxidation. The original design called for the use of a 2 % KMnO4 solution and a 2.5-gal/hr
diaphragm metering pump to oxidize As(III) and Fe(II). The target oxidant dosage was 0.5
mg/L (as Mn). However, modifications were made to include the use of a 20% liquid
NaMnO4 solution and a 1-gal/hr metering pump by the City prior to system startup. In
addition to the metering pump with adjustable stroke length and speed, the chemical feed
system included a 150-gal polyethylene day tank and an overhead mixer. The addition of
NaMnO4 was discontinued after the system startup because the oxidation of As(III) was
accomplished even without the use of any oxidant.
• Iron Removal. Siemens' Type II AERALATER® was used as a pretreatment step for iron
removal. Constructed of carbon steel, the 11-ft diameter package unit was designed to allow
oxidation, detention, and gravity filtration to all occur in a single unit. The system
components were assembled in a stacked circular configuration, with an aeration chamber on
the top, a detention tank in the middle, and four filter cells in the base (Figure 4-8). The
details of these process components are described as follows:
o Aeration. Air for the aluminum aeration unit was supplied by a !/2-hp blower with a
capacity of 855 ftVmin (cfm) at a 3/8-in static pressure. The influent water was aerated
as it passed over a network of 1%-in PVC slats supported by a stainless steel grid.
o Contact. The 11-ft diameter by 11.5-ft high steel detention tank provided 34 min of
contact time to improve the formation of filterable iron floes. The total detention time of
34 min was based on the total volume of 8,550 gal in the detention tank and the freeboard
above the filter.
o Filtration. The four filter cells sitting at the base of the circular unit had a total cross-
sectional area of 95 ft2. Therefore, operating the system at the design flowrate of 250
gpm would result in a hydraulic loading rate of 2.6 gpm/ft2. The filtration bed in each
filter cell consisted of one each 12-in layer of 0.6 to 0.8 mm anthracite and 0.45 to 0.55
mm sand, which were supported by a 14-in layer of gravel underbedding. A steel plate
underdrain was located under the gravel with media retaining strainers.
o Backwash. The filter cells were backwashed manually once per week to remove filtered
particles from the filter media (the system did not have automatic backwash capabilities).
Each cell was backwashed individually at 285 gpm (or 12 gpm/ft2) using filtered water
from the other cells. To initiate the manual backwash, the influent valve on the first cell
was closed and the corresponding backwash valve was opened. The backwash was
continued until visual observation indicated that the backwash water had reached a "light
straw" color. As a result, the duration of the backwash varied based upon operator
observations. Upon completion, the backwash valve was closed and the influent valve on
the first cell was re-opened. The same procedure was followed for the remaining filter
cells. All filter cells had to be backwashed on the same day to ensure consistent
22
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Table 4-3. Design Features of Type II AERALATER® and APU-300 Systems
Parameter
Value
Remarks
Preoxidation
Oxidant Used
2% KMnO4
Changed to 20% NaMnO4 by City
before system startup
AERALA TEff? Pretreatment
Design Flowrate (gpm)
AERALATER® Diameter (ft)
AERALATER® Height (ft)
Aerator Cross-Sectional Area (ft2)
Detention Tank Size (ft)
Detention Tank Volume (gal)
Detention Time (min)
Media Volume (ft3)
Hydraulic Loading Rate to Filter (gpm/ft2)
Backwash Flowrate (gpm)
Backwash Hydraulic Loading (gpm/ft2)
Backwash Frequency (time/week)
Backwash Duration (min)
Wastewater Production (gal/filter cell)
250
11
26
95
11D x H.5 H
8,550
34
190
2.6
285
12
1
~8
2,250
—
—
—
—
Including freeboard above filter
—
24-inbed depth (12-in anthracite and
12-in sand)
—
—
—
Variable based on visual observation
Per vendor estimate
APU-300 Adsorbers
Vessel Size (in)
Cross-Sectional Area (ft2/vessel)
No. of Vessels
Configuration
Media Type
Media Volume (ft3)
Pressure Drop (psi)
63 D x 86 H
21.6
2
Parallel
AD-33
128
4 psi
—
Based on 62 -in inner diameter
—
—
Pelletized media
36-in bed depth or 64 ft3/vessel
Across a clean bed
APU-3QQ Service
Design Flowrate (gpm)
Hydraulic Loading (gpm/ft2)
EBCT (min)
Estimated Working Capacity (BV)
Throughput To Breakthrough (gal)
Average Use Rate (gal/day)
Estimated Media Life (months)
250
5.8
3.8
82,500
79,000,000
48,600
53
—
—
—
Projected by vendor
1 BV = 958 gal
—
Estimated frequency of change-out at
13. 5% utilization
APU-300 Backwash
Pressure Differential Set Point (psi)
Backwash Flowrate (gpm)
Backwash Hydraulic Loading Rate (gpm/ft2)
Backwash Frequency (per quarter)
Backwash Duration (mm/vessel)
Fast Rinse Duration (min/vessel)
Wastewater Production (gal/vessel)
10
200
9.3
1
15
5
4,000
-
-
Per vendor recommendations
-
-
-
23
-------
11'-0" Diameter Type II Aeralater
Waterwash Style Unit
Level Control
Float
6" Influent Connection
8" Cell Influent Valve, Lever Operated
8" Backwash Waste Valve
8" Backwash Waste Pipe
8" Backwash Waste Drop Pipe
Ground Surface
T
CONCEPTUAL
FRONT/SIDE COMBINATION
ELEVATION VIEW
NOT TO SCALE
Drain to Waste
Figure 4-8. Schematic of Type II AERALATER* System (Based on General
Arrangement Drawing Provided by Siemens)
performance of the filter. After all four cells were backwashed, the system effluent valve
was re-opened and the system returned to service. The backwash water produced was
discharged to a sump and then drained by gravity to two backwash water holding tanks
before being pumped to the sewer system.
Adsorption. The AdEdge APU-300 system was fed by two 15-hp high service pumps to
provide pressurized flow to the water tower. The high service pumps were controlled to start
and stop operation based on the water level in the AERALATER® detention tank. The APU-
300 adsorption system consisted of two 63-in diameter, 86-in tall vessels configured in
parallel, each containing 64 ft3 of pelletized AD-33 media supported by gravel underbedding.
Figure 4-9 shows the schematic of the APU-300 system. The adsorption vessels were
constructed of composite fiberglass with a polyethylene liner and rated for 150 pounds per
square inch (psi) working pressure. The system was skid mounted and piped to a valve rack
mounted on a polyurethane-coated, welded frame. The service, backwash, and media
replacement are described in more detail below.
o Service. Water flowed downward through the packed AD-33 media beds. Flow to each
vessel was measured and totalized to record the volume of water treated. The pressure
differential through each vessel also was monitored. Based on a design flowrate of 250
gpm, the empty bed contact time (EBCT) for each vessel was 3.8 min and the hydraulic
loading to each vessel was approximately 5.8 gpm/ft2.
24
-------
System
Feed
Inlet
^
r-i
i
fi
\
-KM-
tent
\
i
^ j
— M3*-
K
^p
i
_k
*S«-r-«S*n
^
$&%/>
w^m
v/mS&i.y-^
^StfAatLf^
Explanation
@ Flow Monitor/Sensor
(p) Pressure Gauge
l®( Butterfly Valve with Electric Actuator
(DF^ Differential Pressure Gauge
System
Outlet
System
~* Backwash
Figure 4-9. Schematic of APU-300 System (Based on Process and
Instrumentation Diagram Provided by AdEdge)
o Backwash. Based upon a set time period or a set pressure differential, the adsorption
vessels were taken off-line one at a time for a manual backwash using raw water from the
wells. The system was equipped with an automatic backwash trigger based on time or
differential pressure, but this feature was disabled. The purpose of the backwash was to
remove particulates and media fines built up in the beds and to uncompress the media
beds. While one vessel was backwashed, the other vessel remained in service. Each
vessel was backwashed at a flow rate of approximately 200 gpm (or 9.3 gpm/ft2). The
backwash water generated was discharged to a sump and then drained by gravity to two
backwash water holding tanks before being pumped to the sewer system.
o Media Replacement. When the AD-33 media arsenic removal capacity is exhausted, the
spent media will be removed from the vessels and disposed off-site. Virgin media is then
loaded back into each vessel. Based on the vendor's estimate, the media will be changed
out after treating approximately 79 million gal or every 53 months (based on an estimated
daily use rate of 48,600 gal for the system and influent arsenic concentrations of 20 to 27
Hg/L). The actual media change-out will be based on the system performance and media
exhaustion. The spent media, which most likely will pass the EPA's TCLP test for
toxicity, will be disposed of as nonhazardous waste.
Post-Treatment Chemical Feed. After the APU-300 system, the treated water underwent
post-chlorination, fluoridation, and polyphosphate addition. Post-chlorination was carried out
with a gas chlorine injection system, which consisted of two 150-lb chlorine gas cylinders, an
electronic scale, a flow controller, and a 3-hp chlorine booster pump. Post-chlorination
helped maintain a target total chlorine residual level of 1.1 mg/L (as C12) in the distribution
system. Fluoride was added at a target level of 1.3 mg/L using a 0.58-gph maximum capacity
diaphragm chemical metering pump and a 65-gal polyethylene storage tank. Blended
polyphosphates were added with a 0.58-gal maximum capacity diaphragm chemical metering
pump and a 50-gal polyethylene storage tank for corrosion control.
25
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4.3 Treatment System Installation
This section provides a summary of the system installation, shakedown, and startup activities and the
associated pre-installation activities, including permitting and building construction.
4.3.1 System Permitting. The system engineering package, prepared by AdEdge and Bolton &
Menk, Inc., included a system design report and associated general arrangement and piping and
instrumentation diagrams (P&IDs) for the Type II AERALATER® and APU-300 systems, electrical and
mechanical drawings and component specifications, and building construction drawings detailing
connections from the system to the entry piping and the City's water and sanitary sewer systems. The
engineering package was certified by a Professional Engineer registered in the State of Minnesota and
submitted to MDH for review and approval on March 21, 2005. After MDH's review comments were
incorporated, the revised package was resubmitted on May 20, 2005. A water supply construction permit
was issued by MDH on June 20, 2005, and fabrication of the system began thereafter.
4.3.2 Building Construction. A permit for building construction was applied for by the City and
issued on June 13, 2005. Building construction began on July 1, 2005, and was completed on February 9,
2006. The concrete block building had a 55.3 ft x 24.7 ft footprint with a sidewall height of 14 ft (see
Figure 4-10). The AERALATER® aeration tower protrudes through the building roof where two 16-in
diameter access hatches also were installed for adsorptive media loading. In addition to housing the
treatment system, the building contains a fluoride room, a chemical room, a bathroom, and some
office/laboratory space. Wastewater discharge is facilitated with a4ftx2ftx2ft(120 gaj) underground
sump that empties by gravity into two 12,500 gal pre-cast concrete holding tanks. Each holding tank is
equipped with a 2-hp sump pump with a design capacity of 50 gpm for transferring backwash water to the
sanitary sewer system.
4.3.3 System Installation, Startup, and Shakedown. Although building construction was still on
going, the site was prepared for delivery of the treatment systems by September 2005. Both units were
shipped and arrived prior to roof construction to facilitate placement in the building. The APU-300
system arrived on September 6, 2005 and the AERALATER® system arrived on September 16, 2006.
The vendor, through its subcontractor, performed the off-loading and installation of the systems,
including connections to the entry and distribution piping and electrical interlocks. Figure 4-11 shows the
off-loading of the AERALATER® unit by crane.
Subsequent to the treatment system delivery, construction work to finish the building and associated
piping and electrical infrastructure continued through February 9, 2006. Siemens arrived on-site for
mechanical checkout of the AERALATER® installation on January 4, 2006. AdEdge was on-site from
January 4 to 11, 2006, for mechanical checkout of the APU-300 installation and start-up activities,
including hydraulic testing, media loading, initial backwashing, and system disinfection. After the
bacteriological test results were received and passed, the systems began to operate manually with the
treated water sent to the distribution system starting from January 18, 2006. Manual operation of the
systems continued until the City's contractor completed the electrical wiring and control setpoints for the
well pumps and high service pumps. The operator began to record operational data on January 30, 2006.
Battelle staff traveled to Stewart, MN to perform system inspections and operator training from February
1 to 3, 2006, with the first set of treatment plant samples taken on February 2, 2006. A punch list was
identified during the trip and later forwarded to AdEdge on February 16, 2006. The issues to be
addressed included replacement of a headless gauge on the AERALATER® system, installation of a
combined effluent sample tap downstream of the APU-300 system and upstream of post-chlorination,
disabling of the APU-300 system automatic backwash, calibration of flow meters for the APU-300
26
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Figure 4-10. Building with AERALATER® Tower (top), Backwash Sump (bottom
left), and Backwash Water Holding Tanks (bottom right) at Stewart, MN
Figure 4-11. Off-Loading and Placement of AERALATER® Unit at Stewart, MN
27
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system, and changes of combined flow totalizer PLC programming for the APU-300 system. These
issues were subsequently resolved by the vendor by August 2006.
4.4
System Operation
The operational parameters for the first six months of the system operation were tabulated and are
attached as Appendix A. Key parameters are summarized in Table 4-4. From January 30, 2006, to
August 1, 2006, the system operated for 890 hr, producing 10,039,000 gal based on wellhead flow
totalizer readings. The wells were operated on an alternating basis with Well No. 3 operating for 432.4 hr
and Well No. 4 for 457.6 hr. The average daily demand was 54,822 gal and the average operation time
was 4.9 hr/day. Given the full design capacity of 250 gpm (360,000 gpd), this represents an average
hydraulic utilization rate of 15% on a daily basis. The peak daily demand was 126,779 gal, which
occurred on July 12, 2006. The system operation is discussed further below in terms of the hydraulic
performance of the AERALATER® and APU-300 systems.
Table 4-4. Treatment System Operational Parameters for Stewart, MN
Parameter
Operational Period
Wellhead Operations
Total Operating Time (hr)
Average Operating Time (hr/day)
Throughput (kgal)
Average Demand (gpd)
Peak Demand (gpd)
AERALATER® Iron Removal Operations
Average Flowrate [Range] (gpm)(a)
Average Contact Time [Range] (min)
Average Filtration Rate [Range] (gpm/ft2)
Average Ap across Filter (ft H2O)
Median Throughput between Backwash [Range]
(kgal)
Median Run Time between Backwash [Range] (hr)
Median Backwash Frequency [Range]
(day/backwash)
APU-300 Adsorption Operations
Throughput (kgal)
Throughput (BV)
Average Flowrate [Range] (gpm)(b)
Average EBCT [Range] (min)
Ap across tank/system (psi)
Value
January 30, 2006 to August 1, 2006
Well No. 3
432.4
2.4
5,012
27,436
85,225
Well 3
194 [121-215]
44 [40-71]
2.0 [1.3-2.2]
—
—
-
—
Tank A
5,282
11,031
90 [73-104]
5.3 [4.6-6.5]
0
Well No. 4
457.6
2.5
5,027
27,532
87,300
Well 4
184 [134-210]
46 [41-64]
1.9 [1.4-2.2]
—
—
-
—
TankB
5,177
10,814
88 [70-103]
5.4 [4.6-6.8]
0
Total
890.0
4.9
10,039
54,822
126,779
Total
—
—
—
<1.5
367.1 [217.1-739.4]
32 [19-65]
7 [5-15]
Total
10,459
10,922
179 [143-207]
5.3 [4.6-6.6]
Ito2
(a) Average flowrate based on readings of individual wellhead mechanical flow totalizers and hour meter.
(b) Average flowrate based on weekly readings of instantaneous flowrate from each vessel using digital
paddlewheel flow meters.
4.4.1 AERALATER® Operations. With an average flowrate of 189 gpm between the two wells,
the AERALATER® system was run at approximately 76% of its full design capacity of 250 gpm. The
flowrate to the AERALATER® system varied slightly based on which well pump was operational. When
Well No. 3 was operational, the flowrate readings ranged from 121 to 215 gpm and averaged 194 gpm.
At these flowrates, the contact times ranged from 40 to 71 min and averaged 44 min (compared to a
28
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design value of 34 min), and the hydraulic loading rates to the filter ranged from 1.3 to 2.2 gpm/ft2 and
averaged 2.0 gpm/ft2 (compared to the design value of 2.6 gpm/ft2). When Well No. 4 was operational,
the flowrate readings ranged from 134 to 210 gpm and averaged 184 gpm. This corresponded to a contact
time of 41 to 64 min and a hydraulic loading rate of 1.4 to 2.2 gpm/ft2. In general, the contact time was
higher, but the hydraulic loading rate was lower than the respective design value.
During this time period, a total number of 25 backwash events took place. The operator manually
backwashed the AERALATER® system approximately once per week with the number of days per
backwash ranging from 5 to 15. During the filter run cycles, less than 1.5 ft of H2O headless was
measured across the filter media beds. The run times between two consecutive backwash events ranged
from 19 to 65 hr and the media run time was 32 hr. The throughput between two consecutive backwash
events ranged from 217,100 to 739,400 gal and the median throughput was 367,100 gal. The throughput
to the filter varied based on the amount of run time required to meet the water demand during the week.
4.4.2 APU-300 Operations. The APU-300 system processed approximately 10,459,000 gal or
10,922 BV of water from January 30 through August 1, 2006, based on the readings from the individual
digital paddle-wheel flow totalizers installed on the effluent piping downstream from the adsorption
vessels. In general, the throughput readings obtained via the paddle-wheel flow totalizers were 5.6%
higher than those from the mechanical totalizers at the wellheads given the wellhead throughput and
estimated backwash water volume. Based on the readings for the individual vessels, Vessel A processed
11,031 BV (5,282,000 gal) and Vessel B processed 10,814 BV (5,177,000 gal) of water. The average
flowrates were 90 and 88 gpm for Vessels A and B, respectively, indicating balanced flow between the
two vessels. The flowrates were recorded at least once per week by the operator based on the
instantaneous readouts on the digital paddlewheel flow meter for each vessel. According to the flowrates
measured, the system operated at approximately 71% of its design capacity. The EBCTs for Vessels A
and B averaged 5.3 and 5.4 min, which are higher than the design value of 3.8 min. Throughout the six-
month operational period, the differential pressure across the media beds and across the entire system
remained low at 1.0 to 2.0 psi, suggesting effective particulate removal by the AERALATER® system.
The two manual backwash events that took place during this study period are discussed in detail below.
4.4.3 Backwash Operations. Both the AERALATER® and APU-300 systems required backwash.
Because the AERALATER® system was used as pre-treatment to remove iron particles, it was
backwashed as often as once per week. The APU-300 system did not experience elevated differential
pressures above the 10-psi setpoint and, therefore, was backwashed only twice during the first six-month
study period. Both units used treated water for backwash. Table 4-5 summarizes key operational
parameters related to system backwash for both systems.
During the six-month study period, 25 manual backwash events were initiated, generating approximately
168,900 gal of backwash water based on the readings obtained via the wellhead totalizer readings before
and after backwash. The amount of wastewater produced represents 1.7% of the volume of water
processed during this time period. The average backwash flowrate was 224 gpm, or 9.4 gpm/ft2, which
was about 21% lower than the design value of 284 gpm or 12 gpm/ft2. The duration for each backwash
event (for all four cells) ranged from 13 to 45 min and averaged 31 min, which is very close to the
vendor-provided value of 8 min/cell or 32 min/event. The backwash duration varied because backwash
was manually controlled by the operator based on visual observations of the backwash water color. The
backwash was discontinued when the backwash water had reached a "light straw" color. The average
amount of wastewater produced was 6,756 gal per backwash event, compared to 9,000 gal per event
provided by the vendor.
29
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Table 4-5. Summary of Backwash Operations at Stewart, MN
Parameter
Value
AERALATER® Backwash Operations
Total Number of Backwash Events
Total Volume of Backwash Wastewater Produced (gal)
Median Frequency of Backwash [Range] (day)
Average Flowrate [Range] (gpm)
Average Hydraulic Loading Rate [Range] (gpm/ft2)
Average Duration [Range] (min)
Average Backwash Wastewater Volume [Range]
(gal/event)
25
168,900
7 [5-15]
224 [173-386]
9.4 [7.3-16.3]
31 [13-45]
6,756 [2,600-12,400]
APU-300 Backwash Operations
Total Number of Backwash Events
Total Volume of Backwash Wastewater (gal)(a)
Backwash Duration (min)
Fast Rinse Duration (min)
Average Backwash Wastewater Volume [Range]
(gal/vessel)
2
13,472
15
3
2,93 5(b) [2,799-4,668]
(a) Backwash water volumes including fast rinse wastewater.
(b) Average values do not include Vessel A backwash initiated and then
halted on February 2, 2006.
For the APU-300 system, it was recommended that the AD-33 media be backwashed approximately once
every 45 days to loosen up the media bed. The system was equipped with an automatic backwash control
that initiated backwash either by a 45-day time trigger or by a differential pressure trigger set at 10 psi
across each vessel. It was necessary to disable this automatic backwash feature due to the process control
configuration of the well pumps and high service pumps at the Stewart, MN site. Per communication
with the operator during the startup trip in February 2006, it was determined that there was no wiring
connection between the APU-300 programmable logic controller (PLC) and the City of Stewart's PLC
that controlled the well pumps and high service pumps. Therefore, if an automatic backwash was called
for while the well pumps and high service pumps were off, there would not be adequate flow to the APU-
300 units to accomplish the backwash. For this reason, the automatic backwash capability was disabled
in the PLC on February 2, 2006, and the operator performed each backwash of the APU-300 unit with a
manual trigger. The backwash trigger was initiated manually twice during the six months of system
operation on February 2, 2006, and February 23, 2006, as described below.
The event on February 2, 2006, occurred during startup activities to confirm proper installation and setup
of the system. During this event, it was noted that further adjustments were required to the PLC settings
and to the backwash flowrate to meet design specifications. During the backwash of Vessel A on
February 2, 2006, a higher than specified backwash flowrate of greater than 275 gpm (or 13 gpm/ft2) was
noted along with visual observation of media loss discharged through the backwash line. Shortly after
initiation of backwash, the operator throttled back the flowrate to approximately 181 gpm (or 8.6
gpm/ft2), a value below the design flowrate of 200 gpm (or 9.5 gpm/ft2). It also was noted that the
backwash and fast rinse time setpoints required adjustment in the PLC. Therefore, the backwash of
Vessel A was halted after 28 min to make these adjustments. The backwash time was changed from
1,200 sec (20 min) to 900 sec (15 min) to match the design value of 15 min. The fast rinse time also was
adjusted from 1,500 sec (25 min) to 180 sec (3 min) to be closer to the design value 5 min. During this
backwash event, Vessels A and B generated 4,668 and 2,979 gal of wastewater, respectively. The
operator subsequently performed a manual backwash event on February 23, 2006, that generated 3,026
30
-------
and 2,799 gal from Vessels A and B, respectively. Except for Vessel A on February 2, 2006, backwash
produced less amounts of wastewater than the design value of 4,000 gal/vessel.
During the first six-months of system operation, backwash of the adsorption vessels produced 13,472 gal
of wastewater, which represents 0.12% of the total amount of water processed. Because no elevated
differential pressure readings across the vessels occurred, it was decided not to backwash the adsorption
vessels for the remainder of the six month time period.
4.4.4 Residual Management. The residuals produced by the treatment system at Stewart, MN
included wastewater produced from the gravity filter and adsorption vessels. Wastewater produced was
discharged to the building sump, which emptied by gravity to two holding tanks and was then pumped to
the sanitary sewer. The total volume of wastewater produced was 182,372 gal, which represents a
wastewater generation rate of approximately 1.8%. The AD-33 media was not exhausted during the first
six months of system operation, so there were no residuals associated with spent media.
4.4.5 Reliability and Simplicity of Operation. No significant scheduled or unscheduled
downtime has been required since installation of the treatment system. The simplicity of system
operation and operator skill requirements are discussed including pre- and post treatment requirements,
levels of system automation, operator skill requirements, preventative maintenance activities, and
frequency of chemical/media handling and inventory requirements.
4.4.5.1 Pre- and Post-Treatment Requirements. Due to the high TOC and ammonia levels in source
water, KMnO4, instead of chlorine, was originally selected to oxidize As(III) and Fe(II). Prior to system
startup, however, the operator indicated his preference of using liquid NaMnO4 instead of powdered
KMnO4. Subsequently, a modification of the initial design was implemented by the City in December
2005 to include the use of a 20% liquid NaMnO4 solution with a 1-gph chemical metering pump. To
achieve the target dosage, the chemical metering pump operated with a 25% stroke and 2.5% speed
settings. Based on measurements with a calibration cylinder, these settings corresponded to a 0.092-gph
application rate, equivalent to only 9.2% of the pump's maximum capacity. The pump size and low
settings contributed to difficulties in controlling the NaMnO4 dose and the pump appeared to have lost
prime after February 2, 2006. Without NaMnO4 injection, it was observed that iron continued to be
removed, presumably by aeration and that As(III) continued to be oxidized to As(V) via unidentified
processes within the AERALATER® gravity filter (see Section 4.5.1.1). No post-treatment requirements
existed related to the arsenic removal system.
4.4.5.2 System Automation. The wellhead and high service pumps were automatically controlled by
a PLC installed by the City. The AERALATER® system did not require significant automation other than
the level sensors in the detention tank that controlled the operation of the high service pumps. The
AERALATER® system did not include automatic backwash triggers, which could be added as a system
upgrade. Because the system needed to be backwashed only weekly, the lack of automation for the
gravity filter backwash was not a significant inconvenience. However, this lack of automation would
likely be an issue at a site requiring more frequent backwash. As noted in Section 4.4.3, it was necessary
to disable the automatic backwash capability of the APU-300 system. It was determined that there was no
wiring connection between the APU-300 PLC and the City's PLC that controlled the well pumps and
high service pumps. Therefore, if an automatic backwash was called for while the well pumps and high
service pumps were off, there would not be adequate flow to the adsorption vessels to accomplish the
backwash. The City decided not to pursue a change to the control system and manually backwash the
adsorption vessels when required.
4.4.5.3 Operator Skill Requirements. Under normal operating conditions, the daily demand on the
operator was approximately 10 min for visual inspection of the system and recording of operational data,
31
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such as pressure, volume, and flowrate on field log sheets. The manual backwash operations required an
average of 31 min of the operator's time once per week. This is equivalent to approximately 1.7 hr of
labor per week. The operator also performed routine weekly and monthly maintenance according to the
users' manual to ensure proper system operation. Normal operation of the system did not appear to
require additional skills beyond those necessary to operate the existing water supply equipment.
For the state of Minnesota, there are five water operator certificate class levels, i.e., A, B, C, D, and E (A
being the highest). The certificate levels are based on education, experience, and system characteristics,
such as water source, treatment processes, water storage volume, number of wells, and population
affected. The certified water operator for the City of Stewart has a Class C certificate. Class C requires a
high school diploma or equivalent with at least three years of experience in operation of Class A, B, or C
systems or a bachelor's degree from an accredited institution with at least one year of experience in the
operation of a Class A, B, C, or D systems.
4.4.5.4 Preventative Maintenance Activities. Recommended maintenance activities for the
AERALATER® system include annual inspection of the aerator internals and slats to monitor iron build-
up and perform cleaning if necessary, a complete interior inspection every two years by Siemens, and
mechanical and electrical aerator blower checks if performance issues arise. Preventative maintenance
tasks for the APU-300 system recommended by the vendor included monthly inspection of the control
panel; quarterly checking and calibration of flow meters; biannual inspection of actuator housings, fuses,
relays, and pressure gauges; and annual inspection of the butterfly valves. The vendor recommended
checking the actuators at each backwash event to ensure that the valves were opening and closing in the
proper sequence. Further, inspection of the adsorber laterals and replacement of the underbedding gravel
was recommended to be performed concurrent with the media replacement. During this six month time
period, two relays that controlled the electrically-actuated values on the APU-300 system were replaced
using spare relays existing in the PLC panel. No other significant repair and maintenance activities were
reported during this reporting period.
4.4.5.5 Chemical Handling and Inventory Requirements. No chemical handling requirements were
necessary because iron removal occurred by aeration and oxidation of As(III) to As(V) was occurring
within the AERALATER® filter (see Section 4.5.1.1). Chemical handling of NaMnO4 was required
initially from January 18 to February 2, 2006.
4.5 System Performance
The performance of the AERALATER® and APU-300 systems were evaluated based on analyses of water
samples collected from the treatment plant, backwash lines, and distribution system.
4.5.1 Treatment Plant. The treatment plant water was sampled on as many as 28 occasions
including two duplicate events and seven speciation events during the first six months of system
operation. Table 4-6 summarizes the analytical results for As, Fe, and Mn. Table 4-7 summarizes the
results of the other water quality parameters. Appendix B contains a complete set of analytical results.
The results of the water samples collected throughout the treatment plant are discussed below.
4.5.1.1 Arsenic. Figure 4-12 presents the results of seven speciation events and Figure 4-13 shows
total arsenic concentrations measured across the treatment train. Total arsenic concentrations in raw
water ranged from 35.5 to 56.4 |o,g/L with As(III) at 27.9 to 40.7 |o,g/L existing as the predominant
species. Low levels of As(V) and participate arsenic also were present, averaging 4.5 |o,g/L and 4.4 |og/L,
respectively. Total arsenic concentrations measured during this study period varied in a wider range than
those measured historically (i.e., 39.0 to 41.7 |o,g/L) as shown in Table 4-1.
32
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Table 4-6. Summary of Arsenic, Iron, and Manganese Results
Parameter
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)(b)
Mn (soluble)1™
Sampling
Location
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TT
Sample
Count
28
28
28
23
22
4
7
7
7
2
1
4
7
7
7
2
1
4
7
7
7
2
1
4
7
7
7
2
1
4
28
28
28
23
22
4
7
7
7
2
1
4
27
27
27
23
21
4
6
6
6
2
4
Concentration (jig/L)
Minimum
35.5
33.5
19.8
0.4
0.3
<0.1
34.1
21.3
18.5
0.4
0.2
<0.1
0.5
<0.1
<0.1
<0.1
<0.1
<0.1
27.9
4.2
<0.1
0.6
0.9
<0.1
1.4
6.1
17.2
<0.1
<0.1
0.1
993
983
<25
<25
<25
<25
412
<25
<25
<25
<25
<25
19.8
20.3
21.9
10.7
7.2
26.4
20.7
20.3
22.0
17.5
26.7
Maximum
56.4
56.9
38.7
7.4
9.2
2.3
44.6
44.9
29.2
0.5
0.2
3.0
8.5
31.1
12.3
0.3
<0.1
0.2
40.7
27.3
2.9
1.7
0.9
0.6
7.0
23.2
26.4
0.1
O.I
2.5
1,491
1,309
27.4
337
524
<25
1,335
68.5
<25
<25
<25
<25
44.3
31.4
47.8
31.2
33.2
34.2
26.1
25.6
41.3
26.0
35.1
Average
42.2
41.9
27.0
_w
_(a>
_W
39.3
33.8
24.7
_w
_w
_w
4.4
11.3
4.6
_w
_w
_w
34.9
22.2
1.2
_w
_w
_w
4.5
11.7
23.4
_w
_w
_w
1,173
1,145
<25
26.7
35.8
<25
904
<25
<25
<25
<25
<25
23.7
24.1
29.8
24.9
26.4
29.6
23.7
23.9
28.5
21.8
29.5
Standard
Deviation
6.0
5.5
4.8
_w
(a)
_W
4.2
7.0
3.5
_w
(a)
_W
2.6
9.6
5.2
_w
_w
(a)
4.4
8.1
1.0
_W
_W
_W
2.1
6.1
3.3
(a)
_(a)
_W
111
91.3
3.1
67.6
109
-
292
21.1
-
-
-
-
4.4
2.3
6.6
5.3
6.7
3.3
1.9
2.0
7.1
6.1
3.8
(a) Average and standard deviation not meaningful for arsenic breakthrough data.
(b) Results from February 2, 2006, sampling event with NaMnO4 addition not included.
33
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Table 4-7. Summary of Other Water Quality Parameter Results
Parameter
Alkalinity
(as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
Sampling
Location
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
Unit
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
NTU
NTU
NTU
NTU
NTU
Sample
Count
28
28
28
23
22
4
11
11
11
6
5
4
7
7
7
2
1
4
7
7
7
2
1
4
11
11
11
6
5
4
28
28
28
23
22
4
28
28
27
23
22
4
28
28
28
23
22
4
Concentration
Minimum
408
410
410
400
367
416
1.0
1.1
0.9
0.6
0.4
1.0
0.3
0.3
0.3
0.4
0.3
0.4
<1
<1
<1
<1
<1
<1
0.05
0.05
0.05
O.05
O.05
0.28
0.25
0.78
0.27
O.03
O.03
O.03
23.3
23.1
23.0
23.3
23.5
24.8
4.1
4.3
0.4
0.4
0.3
0.4
Maximum
454
447
448
454
444
427
1.9
1.9
1.7
1.4
1.7
1.2
0.6
0.5
0.6
0.4
0.3
0.6
<1
<1
<1
<1
<1
<1
0.05
0.05
0.44
1.68
1.58
0.49
1.07
1.05
0.39
0.75
1.03
0.06
28.3
28.2
28.1
28.3
28.6
27.0
15.0
15.0
1.5
2.2
3.5
0.9
Average
424
424
425
423
420
421
1.6
1.6
1.3
1.0
1.0
1.1
0.5
0.4
0.4
0.4
0.3
0.5
<1
<1
<1
<1
<1
<1
0.05
0.05
0.16
0.53
0.53
0.37
0.90
0.89
0.33
0.06
0.08
O.03
25.6
25.3
25.1
25.4
25.4
25.5
6.6
9.2
0.8
0.8
1.1
0.7
Standard
Deviation
10.6
10.5
8.8
13.3
15.3
4.6
0.3
0.3
0.2
0.3
0.5
0.1
0.1
0.1
0.1
0.0
-
0.1
-
-
-
-
-
-
-
-
0.15
0.62
0.62
0.10
0.15
0.06
0.04
0.15
0.21
0.03
.2
.1
.1
.2
.2
.1
2.4
2.0
0.3
0.5
0.8
0.2
34
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Table 4-7. Summary of Other Water Quality Parameter Results (Continued)
Parameter
TOC
pH
Temperature
Dissolved
Oxygen
ORP
Total Hardness
(as CaCO3)
Ca Hardness
(as CaCO3)
Mg Hardness
(as CaCO3)
Sampling
Location
IN
AC
AF
TA
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
IN
AC
AF
TA
TB
TT
Unit
mg/L
mg/L
mg/L
mg/L
mg/L
S.U.
S.U.
S.U.
S.U.
S.U.
S.U.
°c
°c
°c
°c
°c
°c
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mV
mV
mV
mV
mV
mV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
Sample
Count
6
6
6
1
o
J
26
26
26
20
20
5
26
26
26
20
20
5
25
24
24
18
18
5
26
26
26
20
20
5
7
7
7
2
1
4
7
7
7
2
1
4
7
7
7
2
1
4
Concentration
Minimum
6.2
6.2
6.2
6.1
6.1
7.4
7.8
7.7
7.8
7.9
7.7
10.1
10.1
10.5
10.6
10.5
10.8
0.5
3.8
1.6
1.9
1.9
2.4
-36.6
95.9
108
88.7
83.9
137
200
189
206
209
214
206
101
95.0
102
103
113
104
94.0
93.9
93.6
105
101
99.8
Maximum
6.7
7.1
6.8
6.1
6.6
8.2
8.5
8.9
8.4
8.4
8.2
16.6
13.1
19.3
14.3
15.4
11.7
1.9
7.9
5.0
4.7
5.7
6.2
404
349
386
323
321
264
237
236
235
210
214
240
119
118
120
104
113
122
117
118
117
106
101
119
Average
6.4
6.5
6.4
6.1
6.4
7.9
8.2
8.2
8.1
8.2
8.1
11.7
11.3
12.0
11.9
12.0
11.5
1.0
5.3
2.8
2.9
3.1
3.2
194
232
216
189
186
180
217
211
217
210
214
222
112
108
111
104
113
114
105
103
106
106
101
108
Standard
Deviation
0.2
0.4
0.2
-
0.3
0.2
0.2
0.2
0.1
0.1
0.2
1.4
0.7
1.7
1.1
1.2
0.4
0.5
0.9
1.0
0.7
1.0
1.6
141
71.3
66.3
63.9
67.0
51.9
13.6
16.3
10.3
0.6
-
13.7
6.1
9.4
6.4
0.1
-
8.3
10.5
9.8
7.7
0.7
-
9.1
35
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Arsenic Speciation at the Wellhead (IN)
Arsenic Concentration (jig/L)
S 8 g S
-
02/02/06 02/27/06 03/28/06 04/25/06 05/24/06 06/20/06
Date
DAs (particu ate)
• As (III)
DAs(V)
07/18/06
Arsenic Speciation after Contact Tank (AC)
50
=! 40 -
s
c
o
Arsenic Concentra
5 B g
-
—
02/02/06 02/27/06 03/28/06 04/25/06 05/24/06 06/20/06
Date
D As (particulate)
• As (I II)
DAs(V)
07/18/06
Figure 4-12. Arsenic Speciation Results at Wellhead (IN), After Contact Tank (AC), After
Filtration (AF), and After Vessels A and B Combined (TT)
36
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Arsenic Speciation after Filtration (AF)
50-
=! 40
I
30-
02/02/06 02/27/06 03/28/06
04/25/06
Date
05/24/06 06/20/06 07/18/06
Arsenic Speciation after Combined Effluent (TT)
r
•jo
£ 30
02/02/06 02/27/06 03/28/06 04/25/06 05/24/06 06/20/06 07/18/06
Date
Note: Samples from 02/02/06 taken from TB and 02/27/06, 03/28/06 taken from TAdue to absence of combined effluent tap.
Figure 4-12. Arsenic Speciation Results at Wellhead (IN), After Contact Tank (AC), After
Filtration (AF), and After Vessels A and B Combined (TT) (Continued)
37
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30 --
AsMCL= 10ng/L
Bed Volumes (x103)
-At Wellhead (IN)
-After Vessel A (TA)
-After Contact (AC)
-After Vessel B (TB)
After Filtration (AF)
-After Combined Effluent (TT)
Figure 4-13. Total Arsenic Concentrations Across Treatment Train
Arsenic Removal with NaMnO4 Addition. Upon completion of shakedown and startup on January 18,
2006, the treatment system was operated with the addition of NaMnO4 for As(III) and Fe(II) oxidation.
However, the NaMnO4 addition was disrupted due to loss of prime within one week after the first
sampling and speciation event on February 2, 2006, based on the measurements of solution level and
consumption rate in the chemical day tank.
For the February 2, 2006, sampling event, out of 52.3 |o,g/L of total arsenic in raw water, 39.8 |o,g/L was
present as As(III). Iron at 1,240 |o,g/L existed almost entirely as soluble iron. The As(III) and Fe(II)
concentrations were decreased to 4.2 and < 25 |o,g/L, respectively, following NaMnO4preoxidation,
aeration, and detention. About 0.51 mg/L of NaMnO4 (as Mn) was believed to have been added to raw
water based on the difference in total Mn concentrations between the IN and AC sampling locations,
This amount was close to the stoichiometrically-estimated dosage of 0.42 mg/L (as Mn) based on
February 2, 2006, raw water data, and, therefore, should be sufficient to oxidize most, if not all, As(III)
and Fe(II) in raw water. It should be noted, however, that the NaMnO4 target dosage was estimated based
mainly on the levels of soluble As, Fe, and Mn in raw water (see data in Appendix B) and that the
elevated TOC level at 6.7 mg/L could add to the oxidant demand as to be discussed in Section 4.5.1.3.
The As(V) thus formed, along with the pre-existing As(V), was adsorbed onto and/or co-precipitated with
the iron solids formed during the preoxidation step, resulting in 31.1 |o,g/L of particulate arsenic after the
detention tank.
The February 2, 2006, AC location results also indicated the presence of a significant amount of As(V),
i.e., 17.0 (ig/L, after the detention tank, suggesting insufficient naturally occurring iron in raw water for
more complete As(V) treatment to below the 10-|a,g/L MCL. The concentration ratio of soluble iron to
soluble arsenic in raw water was 26:1 on February 2, 2006, which was over the 20:1 target ratio for
38
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effective arsenic removal via iron removal process (Sorg, 2002). The relatively inefficient As(V) removal
observed might be attributed to the relatively high levels of pH (i.e., 8.2), competing anions (1.0 mg/L of
total phosphorous [as PO4] and 27.6 mg/L of Si [as SiO2]), and TOC (i.e., 6.7 mg/L) in raw water, all of
which could adversely impact the As(V) removal by natural iron solids.
The February 2, 2006, results also showed that the gravity filter was highly effective in removing
particulate matter, leaving only 2.7 |o,g/L of particulate arsenic and below the detection limit of iron in the
filter effluent. Also present in the filter effluent were 17.2 |o,g/L of As(V) and 1.3 |o,g/L of As(III). As
expected, As(V) in the filter influent was left essentially untreated. However, As(III) concentrations were
reduced from 4.2 to 1.3 |o,g/L across the filter bed. Conversion of As(III) to As(V) in the gravity filter
also was observed during the subsequent sampling events after the addition of NaMnO4 had been
inadvertently discontinued due to a pump problem. This unexpected finding is discussed in the following
paragraphs.
Arsenic Removal without NaMnO4 Addition. As noted above, after the February 2, 2006, sampling
event, the NaMnO4 metering pump lost prime, thus inadvertently discontinuing NaMnO4 addition for
As(III) oxidation. The disruption of chemical addition was confirmed by both the lack of chemical
consumption in the NaMnO4 day tank and the decrease in Mn concentrations in the AC samples taken
after the detention tank starting from the second sampling event on February 14, 2006.
As typified by the results of the first speciation event on February 27, 2006, since discontinuation of
NaMnO4 addition, very little As(III) conversion occurred via aeration, with 34.2 |o,g/L in raw water and
26.4 |o,g/L following aeration and detention. This observation was consistent with the general notion that
aeration was not effective in oxidizing As(III) (Ghurye and Clifford, 2001). Nonetheless, some As(III)
oxidation still occurred, with As(V) concentrations increasing from 1.4 to 6.1 |o,g/L and particulate arsenic
concentrations from 3.2 to 8.9 |o,g/L after aeration and detention. The amount of particulate arsenic
formed via aeration was 5.7 |o,g/L (i.e., the difference of 3.2 and 8.9 |o,g/L on February 27, 2006),
compared to 22.6 |o,g/L (i.e., the difference of 8.5 and 31.1 |o,g/L) formed following NaMnO4preoxidation
and aeration on February 2, 2006. Note that the levels of soluble iron in February 2 and 27, 2006, raw
water samples were comparable at 1,159 and 1,193 (ig/L, respectively.
As discussed in the Design Manual for the Removal of Arsenic from Drinking Water Supplies by Iron
Removal Process (Hoffman et al., 2006), the use of a chemical oxidant and the point of chemical oxidant
addition are critical to optimize arsenic removal via iron removal process. Research has shown that iron
particles that were formed in the presence of As(V), like the case of preoxidation with NaMnO4, had more
capacity to remove As(V) than pre-formed iron particles, as with the case of aeration. Edwards (1994)
reported that pre-formed iron hydroxides only reached 1/5 to 1/6 of the maximum adsorption density for
iron hydroxides formed in the presence of As(V). The differences in adsorption densities were attributed
to certain mechanisms, i.e., strictly surface adsorption versus adsorption and co-precipitation. Lytle and
Snoeyink (2003) also observed that arsenic removal was lower with pre-formed iron solids, as opposed to
the ideal case of oxidizing both Fe(II) and As(III) at the same time. Consequently, the oxidation of iron
and arsenic should occur at the same time to achieve ideal arsenic removal.
The February 27, 2006 speciation results also showed that, even without the use of NaMnO4, most As(III)
in the filter influent was oxidized to As(V) within the gravity filter, with the As(V) concentration elevated
to 22.4 |o,g/L and particulate arsenic reduced to <0.01 |o,g/L in the filter effluent. The amount of As(V) in
the filter effluent suggested that a portion of the As(V) formed in the filter along with that already existing
in the filter influent was removed, presumably, by attaching to the iron solids accumulating in the filter.
Removal of As(V) also was observed during the other five subsequent speciation events, with removal
rates ranging from 13% to 51% and averaging 28%. These As(V) removal rates were lower than the 57%
39
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As(V) removal rate achieved on February 2, 2006, following NaMnO4 preoxidation. Adsorption of
As(V) on pre-formed iron solids, as discussed above, probably explained why the removal rates were
lower.
As observed above, the gravity filter was effective in removing particulate iron and arsenic, as indicated
by <25 |og/L of iron and <3.2 |o,g/L of particulate arsenic (except for two cases) in the filter effluent
throughout this part of study period. Because As(III) was unexpectedly oxidized to As(V) in the filter
under natural conditions, it was decided to continue the study without the NaMnO4 addition.
In summary, after the use of NaMnO4 was discontinued, the average As(III) and As(V) concentrations
following the contact tank (AC) were 25.1 and 10.8 |o,g/L, respectively. The average As(III) level in the
gravity filter (AF) decreased to 1.2 |o,g/L and As(V) increased to 24.5 |o,g/L (only including data after
February 2, 2006). As shown by Figure 4-13, on average, approximately 34% of total arsenic was
removed by the gravity filter, lower than the 60% occurred during the single sampling event on February
2, 2006, with NaMnO4 addition. Arsenic exiting the gravity filter was removed by the AD-33 media in
the APU-300 system. After approximately 10,900 BV of throughput, the effluent arsenic concentrations
were 2.8 and 3.3 |o,g/L following Vessels A and B, respectively. There was one outlier event on July 25,
2006, as discussed below where total arsenic at 7.4 to 9.2 |o,g/L and total iron at 337 to 534 |o,g/L were
observed in the respective effluent. However, by the next sampling event on August 1, 2006, the effluent
concentration returned to an average of 3.1 |o,g/L and the trend of gradual arsenic breakthrough resumed
as typically would be expected with an adsorption system (see Figure 4-13).
Microbial-Mediated As(III) Oxidation. Since the NaMnO4 addition was ceased, As(III) was
unexpectedly oxidized to As(V) in the gravity filter apparently via certain natural pathways. Figure 4-14
shows the biogeochemical cycle of arsenic as it is transformed between the As(III) and As(V) states in the
environment. This transformation often is mediated by microbial activities. Several researchers have
reported the presence of As(III)-oxidizing bacteria in natural waters, including surface water and
groundwater (Oremland and Stolz, 2003; Battaglia-Brunet et al, 2002; Hambsch et al., 1995), with over
30 strains of microorganisms identified. These microorganisms are categorized in two groups, i.e.,
heterotrophic arsenite oxidizers (F£AOs) and chemolithoautotrophic arsenite oxidizers (CAOs) based on
the pathways involved in arsenite oxidation. The term heterotroph means that the microbe uses organic
carbon substrates for its biomass growth, while the term autotroph means that the microbe uses inorganic
carbon (e.g. CO2) for its biomass growth. These two types of microorganisms oxidize As(III) through the
following mechanisms (Oremland and Stoltz, 2003):
• Heterotrophic Arsenite Oxidizers. The HAOs primarily oxidize As(III) as a
detoxification reaction that converts As(III) to As(V) at the cell membrane. This helps to
inhibit its entry into the cellular structure. This reaction does not create energy or
biomass for the HAO microbe.
• Chemolithoautotrophic Arsenite Oxidizers. The CAOs use As(III) as an electron donor
to reduce oxygen or nitrate and to use the energy to fix CO2 into biomass. The term
chemolithoautotroph refers to the microbe that uses chemical reactions for energy
("chemo") and uses inorganic electron donors ("litho") to fix CO2 into biomass
("autotroph").
Through research efforts under a separate task order, researchers at EPA and Battelle observed similar
naturally-occurring As(III) oxidation processes in a gravity sand filter following aeration at the Greene
County Southern Plant (GCSP) in Beaver Creek, OH. Raw water at the Plant contained 45.9 and 2,280
of total arsenic and iron, both existing almost entirely in the soluble form. Upon aeration and
40
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filtration, As(III) concentrations were reduced from 37.2 |o,g/L (on average) in the filter influent to 1.2
|o,g/L (on average) in the filter effluent. As(V) removal across the filter bed was 77%, much higher than
the 28% observed at the Stewart, MN facility without NaMnO4 preoxidation (Wang, 2006a). Higher
As(V) removal at the GCSP was likely due to the lower pH value at 7.5, which is more favorable for
As(V) adsorption onto iron solids, and the <10 ng/L of total phosphorous, which eliminated a source of
competing species for As(V) removal. At the GCSP, the oxidation of As(III) co-occurred with
nitrification in the filter bed, which converted almost 100% of the 1.2 mg/L of NH3 (as N) (on average) in
the filter influent to NO3" in the filter effluent (Wang, 2006a; Lytle et al., 2007). Nitrification, however,
was determined not to be directly responsible for As(III) oxidation under an internally-funded research
project at Battelle. The results of this study will be further discussed under Section 4.5.1.5.
CH^Q
Qz,
MR TO
Figure 4-14. Biogeochemical Cycle of Arsenic (Oremland et al., 2002)
At the Stewart, MN site, the average As(III) levels declined from 22.2 |o,g/L in the filter influent to 1.2
Hg/L in the filter effluent. The reduction of DO concentrations from 5.3 mg/L after aeration to 2.8 mg/L
after the filter suggested that oxygen was the most likely electron-donor in a biologically mediated
process and that aerobic conditions persist throughout the filter. A portion of DO removal also might be
attributed to the nitrification process that occurred, although this process was shown unrelated to the
As(III) oxidation at the GCSP as described below in Section 4.5.1.5.
4.5.1.2 Iron. Figure 4-15 presents total iron concentrations measured across the treatment train.
Total iron concentrations in raw water ranged from 993 to 1,491 |o,g/L, which existed primarily in the
soluble form with concentrations averaging at 904 |o,g/L. The average soluble iron and soluble arsenic
concentrations in raw water corresponded to a ratio of 23:1, which was just over the 20:1 target ratio for
effective arsenic removal (Sorg, 2002). As discussed above, relatively high pH values and/or high
concentrations of competing anion and TOC in raw water might affect the arsenic removal capacity of the
natural iron solids.
It appears that aeration alone in the AERALATER® unit was sufficient to accomplish complete Fe(II)
oxidation. Soluble iron concentrations after aeration and the detention tank were <25 |o,g/L; complete
conversion of soluble iron to particulate iron was achieved with 1,145 |o,g/L (on average) of particulate
iron following the detention tank. The AERALATER® filter was effective in removing particulate iron,
reducing the iron concentrations to close to or below its detection limit of 25 |o,g/L over the six month
study period. No particulate iron breakthrough was observed from the gravity filter, indicating adequate
filter backwash frequency.
41
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1000--
400--
Fe Secondary MCL = 300 ng/L
10
12
Bed Volumes (x103)
-At Wellhead (IN)
- After Vessel A (T A)
-After Contact (AC)
-After Vessel B (TB)
After Filtration (AF)
-After Combined Effluent (TT)
Figure 4-15. Total Iron Concentrations Across Treatment Train
Following the APU-300 adsorption vessels, iron levels remained at <25 |og/L with the exception of one
outlier event on July 25, 2006, when total iron (as particulate) appeared to breakthrough from Vessels A
and B at 337 and 524 |og/L, respectively. It was not clear what had caused the elevated iron
concentrations observed. The system appeared to operate properly at the time with differential pressure
across the system remained as low as 1 psi. On the subsequent sampling event on August 1, 2006, the
total iron levels from Vessels A and B returned to <25 |o,g/L.
4.5.1.3 Manganese. Manganese concentrations in raw water ranged from 19.8 to 44.3 |o,g/L, which
existed primarily in the soluble form at an average concentration of 23.7 |og/L. Mn removal is discussed
below for treatment system performance both with and without NaMnO4 addition. For the first sampling
event on February 2, 2006, the NaMnO4 feed pump was operational and a total Mn concentration of 541
Hg/L was measured after preoxidation, aeration, and detention. The total Mn concentration following the
AERALATER® gravity filter (AF) was elevated at 127 |o,g/L, which existed entirely as soluble Mn. The
presence of elevated soluble Mn in the filter effluent was unexpected, because the amount of NaMnO4
added was very close to the stoichiometric dosage of 0.42 mg/L (as Mn) for the February 2, 2006, raw
water and should have been completely consumed and converted to MnO2 solids during the preoxidation
step.
The presence of "soluble Mn," instead of MnO2 solids, was probably caused by the presence of high TOC
levels in raw water. It is possible that the "soluble Mn" exiting the filter, in fact, was present in the
colloidal form that could not be effectively removed by the filter and the 0.45-(im disc filters during
speciation. Researchers have reported that high levels of dissolved organic matter (DOM) in source water
can form fine colloidal MnO2 particles, which may not be filterable by conventional gravity or pressure
filters (Knocke et al., 1991). Similar observation also was made at another EPA arsenic demonstration
42
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site at Sauk Centre, MN, where elevated levels of "soluble Mn" at up to 1,062 (ig/L were observed
following the contact tank and Macrolite® pressure filters as the KMnO4 dosage was progressively
decreased from 3.8 to 1.4 mg/L (as Mn) due to concerns over overdosing. (Note that similar to the
Stewart, MN system, KMnO4 was used for the Sauk Centre, MN system to preoxidize as much as 23 and
2,691 (ig/L of As(III) and Fe(II), respectively, due to the presence of 4.0 mg/L of TOC.) "Soluble Mn"
eventually was reduced as low as 2.5 (ig/L as the KMnO4dosage was increased to 5.6 mg/L (as Mn).
This was due to the fact that by increasing the KMnO4 dosage the effect of DOM on Mn(II) oxidation was
overcome and more filterable particles were formed (Shiao et al., 2007).
At the Stewart site, because the high Mn levels at 127 |o,g/L exiting the gravity filter occurred only for a
very short duration, their effects on arsenic adsorption on the AD-33 media should be minimal. Mn,
possibly present in the colloidal form, appeared to have been removed by the AD-33 media, with total Mn
levels of 3.7 |o,g/L measured following the adsorption vessels on February 2, 2006. However, these
elevated colloidal Mn levels in the treated water could have become an issue for media performance if
NaMnO4 dosing had continued at the same dosage rate as on February 2, 2006. If it is later decided to re-
start the NaMnO4 addition, ajar test is recommended to determine the NaMnO4 dosage that would be
high enough to overcome the effects of DOM in raw water and minimize Mn effluent levels to the AD-33
media. At other EPA demonstration sites with pre-chlorination, such as the Rollinsford, NH site, high
Mn loading was found to coat and/or foul the AD-33 media (Oxenham et al., 2005). At this site, the
presence office chlorine promoted the removal of Mn(II) onto the AD-33 media surface.
After the February 2, 2006, sampling event when the NaMnO4 chemical feed pump lost prime,
manganese levels after the contact tank (AC) declined dramatically to levels close to the influent levels at
21 |og/L by the next sampling event on February 14, 2006 (see Figure 4-16). Total Mn levels exiting the
AERALATER® filter continued to be elevated at 37.2 to 47.8 |o,g/L relative to influent levels until March
6, 2006. From February 2 until March 6, 2006, manganese removal across the AD-33 adsorption vessels
continued for approximately 2,500 BV and then became equal to the influent values by March 14, 2006.
These results suggest that the AD-33 media had only a limited capacity for Mn removal (present as Mn2+
ions). As discussed in Section 4.5.1.1, theNaMnO4 addition was not resumed during the reminder of the
study period.
4.5.1.4 pH, DO, and ORP. pH values of raw water ranged from 7.4 to 8.2 and averaging 7.9. pH
values increased slightly from an average value of 7.9 at the wellhead to 8.2 after the AERALATER®
filter. Aeration probably contributed to this increase in pH. DO levels averaged 1.0 mg/L in raw water
and increased to an average value of 5.3 mg/L after aeration. DO concentrations decreased by about 47%
to an average value of 2.8 mg/L across the AERALATER® filter. The aerobic biological processes
responsible for As(III) oxidation and nitrification processes might have consumed some of the DO in the
filter influent (Sawyer et al., 2003). The average DO levels after the APU-300 system ranged from 2.9 to
3.2 mg/L, essentially the same as those that went into the system. ORP levels followed a similar pattern
with an initial increase from 194 mV (on average) in raw water to 232 mV after aeration and the detention
tank. Again, due to the biological processes, ORP readings decreased slightly to 216 mV (on average)
after the AERALATER® filter. ORP levels ranged from 180 to 189 mV after the APU-300 system.
4.5.1.5 Ammonia and Nitrate. Eleven sampling events took place for ammonia and nitrate during
this study period. Figure 4-17 presents ammonia and nitrate concentrations across the treatment train. In
raw water, ammonia concentrations ranged from 1.0 to 1.9 mg/L (as N) and averaged 1.6 mg/L (as N);
nitrate concentrations were consistently less than the method reporting limit of 0.05 mg/L (as N).
Following aeration and detention, ammonia and nitrate concentrations remained essentially unchanged,
although up to 0.3 mg/L (as N) of concentration increases or decreases were observed for ammonia
between the IN
43
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Bed Volume (x1
-------
and AC sampling locations. After 69 days of system operation on March 28, 2006, some ammonia
removal was observed across the gravity filter and AD-33 adsorption vessels. Ammonia removal across
the gravity filter increased from 0.1 mg/L (as N) on Days 69 to 126 to as much as 0.4 mg/L (as N) after
Day 153. After Day 69, ammonia removal across the AD-33 adsorption vessels remained at 0.1 to 0.3
mg/L (asN).
Nitrate concentrations remained below 0.05 mg/L (as N) until April 25, 2006, or 97 days after the system
startup, and then increased to as high as 0.4 mg/L (as N) across the gravity filter and to 0.2 mg/L across
the adsorption vessels. The concentration changes between ammonia and nitrate appear to have a
stoichiometric relationship at these sampling locations.
The decreasing ammonia and DO concentrations and increasing nitrate concentrations indicate that
significant nitrification was occurring within the gravity filter and AD-33 adsorption vessels after
approximately 69 to 97 days of system operation. The 69 day timeframe was based on the observation of
ammonia removal, while the 97 day timeframe was based on detectable levels of nitrate in the gravity
filter effluent. Under the aerobic conditions in the AERALATER® filter, nitrifiers, including
Nitrosomonas and Nitrobacters, can convert ammonia to nitrite and then to nitrate following the reaction
equations (Sawyer et al, 2003):
2NH3 + 3O2 = 2NO2- +2H+ + 2H2O [Nitrosomonas]
2NO2" + O2 = 2NO3 [Nitrobacter]
Through research efforts funded separately by EPA and Battelle, researchers have observed similar
nitrification processes occurring in gravity filters at the GCSP in Beaver Creek, OH that has a similar
treatment train (i.e., aeration and gravity filtration) to the Stewart, MN system (Lytle et al., 2007; Wang,
2006a). In addition, As(III) to As(V) oxidation also was observed possibly through biologically-mediated
processes. Based on laboratory column tests conducted with filtered raw water and filter media obtained
from the GCSP, it was observed that As(III) oxidation continued to occur even after the nitrification
processes had been completely inhibited by lowering the influent pH values to < 5.0 (Clark et al., 1977).
This suggests that nitrification is not necessary for the microbial-mediated As(III) oxidation to occur
(Wang, 2006b). The same study also showed that, after the filter media in the column had been sterilized
with HgCl2, the pathways responsible for As(III) oxidation apparently were disrupted, thus allowing
As(III) to breakthrough from the column with the same amount of As(III) measured both in the column
influent and effluent. Furthermore, because significant nitrification was not observed for 97 days
compared to 40 days for As(III) oxidation, it was very likely that oxygen, instead of nitrate was the
electron acceptor for the microbial-mediated As(III) oxidation process. As discussed above, there was a
47% DO removal rate across the filter with approximately 2.8 mg/L of O2 in the filter effluent, suggesting
the persistence of aerobic conditions through the filter.
4.5.1.6 Other Water Quality Parameters. Alkalinity, fluoride, sulfate, silica, TOC, temperature, and
hardness levels remained consistent across the treatment train and were not significantly affected by the
treatment process (Table 4-7). TOC levels were elevated at 6.4 mg/L in raw water and remained
unchanged across the treatment train. Although high TOC levels might have contributed to the oxidant
demand, they did not appear to have been adsorbed onto iron solids. Total phosphorus (as PO4) decreased
from an average concentration of 0.90 mg/L in raw water to an average concentration of 0.33 mg/L after
the AERALATER® filter. Removal of total phosphorus (as PO4) also occurred on the AD-33 media with
its concentrations reduced to less than 0.1 mg/L (as PO4) after the AD-33 adsorption vessels in most
cases. Turbidity also decreased from 6.6 nephelometric turbidity units (NTU) in the raw water to <1.0
NTU after the AERALATER® filter and APU-300 system.
45
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4.5.2 Backwash Water Sampling. Table 4-8 presents the analytical results of six monthly
backwash water sampling events for two AERALATER® filter cells. The backwash water ranged from
7.9 to 8.1 for pH, 404 to 454 mg/L for TDS, and 28 to 260 mg/L for TSS. The wide range in TSS values
observed was attributed to the fact that grab samples were taken directly from the backwash water
discharge dump. The average TSS level over this time period was 108 mg/L. Concentrations of total
arsenic, iron, and manganese ranged from 168 to 844 |o,g/L, 17 to 111 mg/L, and 41 to 109 |o,g/L,
respectively, with the majority existing as particulate. Assuming that 6,756 gal of backwash water was
produced, on average, from each backwash cycle for four filter cells, approximately 6.1 Ib of solids
(including 0.02 Ib of arsenic, 2.6 Ib of iron, and 0.004 Ib of manganese) would be generated and
discharged per backwash cycle. The quantity of backwash water and amount of backwash solids to be
discharged during AERALATER® filter backwash will be further monitored during the next six months
of system operation with composite backwash samples.
The quantity of backwash water and amount of backwash solids generated during AD-33 adsorption
vessels backwash also will be determined during the next six months of system operation with composite
backwash samples.
4.5.3 Distribution System Water Sampling. Table 4-9 summarizes the results of the distribution
system water sampling. The water quality was similar among the three residences, except for relatively
high iron levels on three occassions at DS3 after system startup. Water quality significantly improved
after the treatment system began operation. Arsenic, iron, and lead concentrations decreased from
average baseline levels of 31.2, 376, and 2.2 |o,g/L to 5.5, 56, and 0.11 |og/L, respectively, after system
startup. Alkalinity, pH, manganese, and copper concentrations remained fairly consistent. Thus, the
treatment system appeared to have beneficial effects on the water quality in the distribution system. In
general, the arsenic levels were significantly higher in the distribution system water compared to the
treatment system effluent (i.e., 5.5 |o,g/L versus 0.9 |o,g/L on average), although still below the 10 |o,g/L
MCL. Higher iron levels also were observed in the distribution system water compared to the treatment
system effluent (i.e., 56 |o,g/L versus <25 |o,g/L on average).
4.6 System Cost
The cost of the system was evaluated based on the capital cost per gpm (or gpd) of the design capacity
and the O&M cost per 1,000 gal of water treated. This required the tracking of the capital cost for the
equipment, site engineering, and installation and the O&M cost for media replacement and disposal,
electricity consumption, and labor. These costs do not include building costs or instrumentation and
control upgrades installed by the City of Stewart.
4.6.1 Capital Cost. The capital investment for equipment, site engineering, and installation for the
250-gpm treatment system was $367,838. The equipment cost was $273,873 (or 74.4% of the total
capital investment), which included $125,555 for a Siemens' Type II AERALATER® system, $126,482
for a skid-mounted APU-300 system, $17,952 for ancillary equipment, and $3,884 for freight (as shown
in Table 4-10). The Siemens' Type II AERALATER® system included a 11-ft diameter steel unit (which
was composed of an aerator, a fan, a detention tank, and a four-cell filter for a total of $77,000), process
valves and piping ($32,060), instrumentation and controls ($7,420), 190 ft3 of sand ($8,400), and other
materials ($675). The APU-300 system included two skid-mounted fiberglass vessels ($45,360), process
valves and piping ($19,460), instrumentation and controls ($20,860), 128 ft3 of AD-33 media ($32,000 or
$250/ft3), and $8,802 for other materials.
46
-------
Table 4-8. Backwash Water Sampling Results
Sampling Event
No.
1
2
3
4
5
6
Date
03/01/06W
03/22/06
04/12/06
05/31/06
06/28/06
07/26/06
BW1
Backwash Filter Cell No 1
31
o
s.u.
8.1
8.0
8.0
8.0
7.9
7.9
2
mg/L
426
432
428
454
430
428
mg/L
36
46
38
260
122
100
CO
.2
?
Mg/L
231
176
168
844
538
403
O!
_Q
zj
8.
3
H9/L
NA
26.8
30.2
26.7
30.9
59.1
As (particulate)
Mg/L
NA
149
138
817
507
343
ro
•5
05
Hg/L
28,765
18,262
16,691
73,492
69,635
50,511
o>
.Q
rj
8.
Q. ^ ^ ^
-------
Table 4-10. Capital Investment Cost for Siemens and AdEdge Treatment System
Description
Quantity
Cost
% of Capital
Investment Cost
Equipment Costs
Siemens Type II AERALATER®
11 -ft Diameter Steel, Epoxy-Lined Unit Including
Aerator, Fan, Detention tank, and Filter
Filter Media (ft3)
Process Valves and Piping
Instrumentation and Controls
Additional Sample Taps
Subtotal
1
190
1
1
1
$77,000
$8,400
$32,060
$7,420
$675
$125,555
—
-
-
-
-
-
AdEdge APU-300 System
63 -in Diameter Fiberglass Vessels on Skid
AD-33 Media (ft3)
Gravel Underbedding
Process Valves and Piping
Instrumentation and Controls
Totalizer for Backwash Line
O&M Manuals
One-Year O&M Support
Subtotal
2
128
1
1
1
2
-
-
$45,360
$32,000
$1,540
$19,460
$20,860
$2,422
$1,080
$3,760
$126,482
-
-
-
-
-
-
-
-
-
Ancillary Equipment
KMnO4 Feed System
Booster Pumps
Motor Controls/MCC/HOA for Pumps
In-Line Mixer
Subtotal
1
2
1
1
$4,192
$6,580
$6,850
$330
$17,952
-
-
-
-
Freight
Freight-AD33 Media (Ib)
Freight-Filter Media (Ib)
Freight-System (Ib)
Freight-Ancillary Equipment
Subtotal
Equipment Total
4,460
10,000
26,000
1
-
$780
$680
$2,112
$312
$3,884
$273,873
-
-
-
-
74.4%
Engineering Cost
Vendor Labor
Vendor Travel
Vendor Material
Subcontractor Labor
Subcontractor Travel
Subcontractor Material
Engineering Total
-
-
-
-
-
-
$4,534
$2,480
$98
$8,400
$420
$588
$16,520
4.5%
Installation Cost
Vendor Labor
Vendor Travel
Subcontractor Mechanical
Subcontractor Electrical
Subcontractor Other Labor
Installation Total
Total Capital Investment
-
-
-
-
-
-
-
$7,920
$3,800
$39,985
$21,890
$3,850
$77,445
$367,838
21.1%
100%
48
-------
The engineering cost included the cost for the preparation and submission of an engineering submittal
package, including process flow diagram of the treatment system, mechanical drawings of the treatment
equipment, and a schematic of the equipment footprint as discussed in Section 4.3.1, and the attainment of
the required state permit for the implementation of the system. The engineering cost was $16,520, which
was 4.5% of the total capital investment.
The installation cost included the equipment and labor to unload and install the AERALATER® and skid-
mounted APU-300 systems, perform piping tie-ins and electrical work, and load and backwash the media
in both AERALATER® filter and AD-33 adsorption vessels (see Section 4.3.3). The installation was
performed by AdEdge and a local subcontractor. The installation cost was $77,445, or 21.1% of the total
capital investment.
The capital cost of $367,838 was normalized to $l,471/gpm ($1.02 gpd) of design capacity using the
system's rated capacity of 250 gpm (or 360,000 gpd). The capital cost also was converted to an
annualized cost of $34,720/yr using a capital recovery factor (CRF) of 0.09439 based on a 7% interest
rate and a 20-yr return period. Assuming that the system operated 24 hr/day, 7 day/wk at the design
flowrate of 250 gpm to produce 131,400,000 gal/yr, the unit capital cost would be $0.26/1,000 gal.
During the first six months, the system produced 10,039,000 gal of water (see Table 4-4). At this reduced
rate of usage, the unit capital cost increased to $1.73/1,000 gal.
4.6.2 Operation and Maintenance Cost. The O&M cost included items such as media
replacement and disposal, electricity, and labor (see Table 4-11). There was no associated chemical cost
after NaMnO4 addition was discontinued. Although the adsorptive media was not replaced during the
first six months of system operation, the media replacement cost would represent the majority of the
O&M cost. The vendor estimate was $41,370 for replacement of 128 ft3 media in the two APU-300
vessels. Because media replacement did not take place, the cost per 1,000 gal of water treated was
calculated as a function of projected media run length using the vendor cost estimate (see Figure 4-18).
This cost includes new media, gravel underbedding, labor, travel, equipment rental, and freight. The
O&M cost will be further refined once the actual breakthrough occurs and the media replacement costs
are incurred. A comparison of the electrical bills before and after system installation will be conducted
for the one-year study period. Routine labor activities for O&M consumed 10 min/day for operational
readings and 31 min/wk for one manual backwash event. This is equivalent to 1.7 hr/wk on a seven day
per week basis. The estimated labor cost is $0.07/1,000 gal of water treated.
49
-------
$4.00
$3.75
$3.25
$2.50
$2.25
o
°- $2.00
S $1.75
$1.25
$0.75
$0.50
$0.00
-O&M cost
- Media replacement cost
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Media Working Capacity, Bed Volumes (x1000)
Figure 4-18. Media Replacement and O&M Cost for AERALATER8
and APU-300 Systems at Stewart, MN
Table 4-11. O&M Cost for City of Stewart, MN Treatment System
Cost Category
Volume Processed (Kgal)
Value
10,039
Assumptions
Through August 1, 2006
Media Replacement and Disposal
Media Cost ($/ft3)
Total Media Volume (ft3)
Media Replacement Cost ($)
Gravel Underbedding Cost ($)
Labor, Travel, and Equipment Cost ($)
Freight ($)
Subtotal
Media Replacement and Disposal Cost
($71,000 gal)
$250
128
$32,000
$1,650
$6,940
$780
$41,370
See Figure 4-18
Vendor quote
Two vessels
Vendor quote
Vendor quote
Vendor quote
Vendor quote
Vendor quote
Based upon media run length at 10 |ag/L
arsenic breakthrough
Chemical Usage
Chemical cost ($)
—
No chemicals required after KMnO4
oxidation discontinued.
Electricity
Incremental cost ($71,000 gal)
—
To be determined on annual basis.
Labor
Average weekly labor (hrs)
Labor cost ($71,000 gal)
Total O&M Cost/1,000 gallons
1.7
$0.07
See Figure 4-18
10 mm/day, plus 3 1 min manual backwash
Average labor rate = $16.33/hr
-
50
-------
5.0 REFERENCES
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selection, characterization, and performance in reactors. Journal of Applied Microbiology, Vol.
93, No. 4. p. 656-67
Battelle. 2004. Quality Assurance Project Plan for Evaluation of Arsenic Removal Technology.
Prepared under Contract No. 68-C-00-185, Task Order No. 0029, for U.S. Environmental
Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH.
Chen, A.S.C., L. Wang, J. Oxenham, and W. Condit. 2004. Capital Costs of Arsenic Removal
Technologies: U.S. EPA Arsenic Removal Technology Demonstration Program Round 1.
EPA/600/R-04/201. U.S. Environmental Protection Agency, National Risk Management
Research Laboratory, Cincinnati, OH.
Clark, J.W., W. Viessman, and M.J. Hammer. 1977. Water Supply and Pollution Control. Third
Edition. Thomas Y. Crowell Company, Inc., New York, NY.
Edwards, M. 1994. "Chemistry of Arsenic Removal during Coagulation and Fe-Mn Oxidation."
JAWWA, 86(9): 64.
Edwards, M., S. Patel, L. McNeill, H. Chen, M. Frey, A.D. Eaton, R.C. Antweiler, and H.E. Taylor.
1998. "Considerations in As Analysis and Speciation" JAWWA, 90(3): 103-113.
EPA. 2003. Minor Clarification of the National Primary Drinking Water Regulation for Arsenic. Federal
Register, 40 CFRPart 141.
EPA. 2002. Lead and Copper Monitoring and Reporting Guidance for Public Water Systems.
EPA/816/R-02/009. U.S. Environmental Protection Agency, Office of Water, Washington, D.C.
EPA. 2001. National Primary Drinking Water Regulations: Arsenic and Clarifications to Compliance
and New Source Contaminants Monitoring. Federal Register, 40 CFR Part 9, 141, and 142.
Ghurye, G., and D. Clifford. 2001. Laboratory Study on the Oxidation of Arsenic III to Arsenic V.
EPA/600/R-01/021. U.S. Environmental Protection Agency, National Risk Management
Research Laboratory, Cincinnati, OH.
Hambsch, B., Raue, B., and H.J. Brauch. 1995. Determination of arsenic(III) for the investigation of the
microbial oxidation of arsenic(III) to arsenic(V). Ada Hydrochimica etHydrobiologica, 23(4):
166-172.
Hoffman, G., D. Lytle, T. Sorg, A.S.C. Chen, and L. Wang. 2006. Design Manual. Removal of Arsenic
from Drinking Water Supplies by Iron Removal Process. EPA/600/R-06/030. U.S.
Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati,
OH.
Knocke, William R., Van Venschoten, John E., Kearney, Maureen J., Soborski, Andrew W., Reckhow,
David A. 1991. "Kinetics of Manganese and Iron Oxidation by Potassium Permanganate and
Chlorine Dioxide." JAWWA 83(6): 80-87.
51
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Lytle, D.A., and V.L. Snoeyink. 2003. "The Effect of Dissolved Inorganic Carbon on the Properties of
Iron Colloidal Suspensions." J. Water Supply: Res. and Tech. AQUA, 52(3): 165-180.
Lytle, D.A., T. J. Sorg, C. Muhlen, L. Wang, M. Rahrig and K. French. 2007. "Biological Nitrification in
a Full-scale and Pilot-scale Iron Removal Drinking Water Treatment Plant. J. Water Supply: Res.
and Tech. AQUA, 56(2): 125-136.
Oremland, R.S., S.E. Hoeft, J.M. Santini, N. Bano, RA. Hollibaugh, and J.T. Hollibaugh. 2002.
"Anaerobic Oxidation of Arsenite in Mono Lake Water and by a Facultative, Arsenite-Oxidizing
Chemoautotroph, Strain MLHE-1." Applied and Environmental Microbiology, 68(10): 4795-
4802.
Oremland, R.S. and J.F. Stolz. 2003. "The Ecology of Arsenic." Science, 300(5): 939-944.
Oxenham, J., Chen, A.S.C, and L. Wang. 2005. Arsenic Removal from Drinking Water byAdsorptive
Media. EPA Demonstration Project at Rollinsford, NH: Six-Month Evaluation Report. Prepared
under Contract No. 68-C-00-185, Task Order No. 0019 for U.S. Environmental Protection
Agency, National Risk Management Research Laboratory, Cincinnati, OH. EPA 600-R-05-116.
Sawyer, C.N., McCarty, P.L., and G.F. Parkin. 2003. Chemistry for Environmental Engineering and
Science. 5th Edition. McGraw-Hill Companies, Inc., New York, NY.
Shiao, H.T., W.E. Condit, and A.S.C. Chen. 2007. Arsenic Removal from Drinking Water by Iron
Removal. EPA Demonstration Project at Big Sauk Lake Mobile Home Park in Sauk Centre, MN.
Six Month Evaluation Report. Prepared under Contract No. 68-C-00-185, Task Order No. 0029
for U.S. Environmental Protection Agency, National Risk Management Research Laboratory,
Cincinnati, OH.
Sorg, T.J. 2002. "Iron Treatment for Arsenic Removal Neglected." Op/low, AWWA, 28(11): 15.
Wang, L., W. Condit, and A.S.C. Chen. 2004. Technology Selection and System Design: U.S. EPA
Arsenic Removal Technology Demonstration Program Round 1. EPA/600/R-05/001. U.S.
Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati,
OH.
Wang, L. 2006a. Long-Term Performance of Full-Scale Water Treatment Systems at Greene County,
Ohio Evaluation of Treatment Technology for the Removal of Arsenic from Drinking Water.
Letter Report for Contract No. 68-C-00-185, Task Order No. 20. U.S. Environmental Protection
Agency, National Risk Management Research Laboratory, Cincinnati, OH.
Wang, L., Chen, A.S.C., L. N. Tong, and A. Paolucci. 2006b. Evaluation ofAs(III) Oxidation via
Microbial-MediatedProcesses. Report preapred under Battelle's Internal Research and
Development Program for Fiscal Year 2006, Columbus, OH.
52
-------
APPENDIX A
OPERATIONAL DATA
-------
US EPA Arsenic Demonstration Project AT Stewart, MN - Daily System Operation Log Sheet
Week
No.
1
2
3
4
5
6
7
8
9
Day of
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Date
01/30/06 7:35 AM
01/31/06 7:00 AM
02/01/06 7:30 AM
02/02/06 6:30 AM
02/03/06 8: 10 AM
02/04/06 8: 15 AM
02/05/06 8: 50 AM
02/06/06 8: 15 AM
02/07/06 7: 10 AM
02/08/06 8:35 AM
02/09/06 8:00 AM
02/10/06 9:10 AM
02/1 1/06 8: 10 AM
02/1 2/06 8: 15 AM
02/13/06 7:15 AM
02/14/06 7:30 AM
02/15/06 7:30 AM
02/16/06 7:35 AM
02/17/06 8:00 AM
02/18/06 9:00 AM
02/1 9/06 8: 30 AM
02/20/06 9:00 AM
02/21/06 8:00 AM
02/22/06 8:45 AM
02/23/06 7:30 AM
02/24/06 7:50 AM
02/25/06 8: 15 AM
02/26/06 9: 30 AM
02/27/06 6:30 AM
02/28/06 10: 15 AM
03/01/06 7: 15 AM
03/02/06 8: 15 AM
03/03/06 7:45 AM
03/04/06 8:30 AM
03/05/06 8: 30 AM
03/06/06 6:40 AM
03/07/06 7:00 AM
03/08/06 8:00 AM
03/09/06 7:50 AM
03/10/06 7:30 AM
03/11/06 10:00 AM
03/1 2/06 9: 15 AM
03/13/06 7:10 AM
03/14/06 6:30 AM
03/15/06 7:45 AM
03/16/06 7:15 AM
03/17/06 7:50 AM
03/18/06 6:45 AM
03/1 9/06 7: 30 AM
03/20/06 7:30 AM
03/21/06 7:00 AM
03/22/06 10:00 AM
03/23/06 7:30 AM
03/24/06 7:30 AM
03/25/06 7:30 AM
03/26/06 9: 30 AM
03/27/06 7:30 AM
03/28/06 6: 15 AM
03/29/06 6:55 AM
03/30/06 8:30 AM
03/31/06 6:55 AM
04/01/06 11:30 AM
04/02/06 9: 40 AM
Well 3
Daily Op
Hours
hrs/day
NA
1.13
3.82
2.09
2.99
1.79
1.95
2.05
1.15
1.79
2.05
1.62
1.98
0.90
1.88
1.88
1.70
1.89
0.88
1.73
2.04
1.96
1.88
1.75
1.90
0.89
2.75
1.62
1.94
1.73
2.17
1.82
1.94
1.36
1.70
2.38
2.07
1.92
2.01
1.93
1.63
1.45
1.53
1.85
1.62
1.33
3.51
1.89
1.55
1.90
0.92
1.60
1.45
1.80
2.00
1.85
2.18
2.11
1.07
1.88
2.14
2.18
2.17
Gallon
Usage
gpd
NA
NA
43,494
24,000
36,468
21,625
22,161
24,290
12,358
21,624
23,675
19,359
22,957
10,962
23,374
21,674
20,800
22,522
11,304
20,640
23,489
23,608
23,270
20,461
22,259
11,441
33,420
19,675
23,429
20,670
25,600
20,928
22,672
16,291
10,480
36,401
24,559
22,272
23,564
22,208
20,015
17,342
18,068
22,320
19,485
16,545
42,956
21,679
19,685
22,300
11,030
19,289
17,972
19,700
23,500
21,138
25,091
25,002
11,968
21,952
24,732
25,777
24,577
Average
Flowrate
gpm
NA
194
190
192
203
201
189
198
179
201
193
199
193
204
207
192
204
198
213
199
192
201
206
195
195
215
202
203
201
199
196
191
195
200
NA
NA
198
193
195
192
205
200
196
201
201
208
204
192
211
196
200
201
206
182
196
191
192
198
186
195
193
197
189
Well 4
Daily Op
Hours
hrs/day
NA
0.00
2.06
1.77
2.62
1.49
1.85
1.84
1.78
1.61
1.33
2.48
1.04
2.59
1.98
1.98
1.10
2.09
2.56
1.63
2.04
1.96
2.30
1.16
2.53
1.87
1.97
1.43
2.06
1.64
1.03
2.59
1.84
1.65
1.80
1.84
1.87
1.73
1.71
1.12
2.63
2.17
2.08
2.06
0.95
2.04
1.95
1.05
2.04
2.10
1.94
1.87
2.68
1.80
1.60
1.94
1.20
1.90
1.65
1.69
1.07
2.27
0.97
Gallon
Usage
gpd
NA
NA
23,412
20,661
11,782
37,171
20,990
21,011
20,212
18,885
15,681
26,988
18,157
20,927
23,165
22,070
12,200
22,721
21,231
25,632
22,570
21,159
24,939
13,770
28,905
20,614
21,919
15,778
21,943
19,114
11,886
30,144
20,528
18,618
14,480
28,497
21,008
20,256
19,536
12,879
30,521
23,226
23,544
22,731
10,646
22,877
20,990
11,834
22,885
23,000
21,957
20,267
30,698
20,000
18,400
21,323
13,855
21,943
18,876
18,762
12,205
26,365
11,044
Average
Flowrate
gpm
NA
NA
190
194
NA
NA
189
190
189
196
196
181
NA
NA
195
186
185
181
NA
NA
184
180
181
197
190
183
186
184
178
194
193
194
186
188
134
NA
187
195
190
192
194
179
189
184
187
187
179
188
187
183
189
181
191
185
192
183
192
193
190
185
190
194
189
AERALATER
Backwash
Yes/No
No
No
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes
No
No
No
No
Yes
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
No
No
No
Yes
No
No
APU-300 Unit
Vessel A
Flow Rate
gpm
92
92
92
NA
NA
92
92
NA
NA
NA
NA
NA
88
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
82
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
103
NA
NA
NA
NA
NA
NA
104
NA
NA
NA
101
NA
NA
104
NA
NA
NA
NA
NA
Vessel A
Service
Totalizer
gal
282,600
288,114
318,183
337,773
365,977
384,714
406,021
426,860
442,802
463,684
480,412
502,250
532,156
541,319
563,172
585,122
601,420
623,167
639,994
661,073
682,816
704,779
726,872
742,579
763,415
778,326
797,262
814,936
835,831
856,567
872,014
971,158
992,853
,000,897
,031,633
,054,674
,007,817
,100,817
,119,988
,140,465
,163,976
,181,234
,203,680
,226,174
,242,433
,259,485
,291,047
,307,759
,330,633
,350,435
16,886
40,391
56,671
79,796
99,025
123,300
144,965
168,523
185,370
208,268
226,074
254,724
272,088
Cumulative
Bed
Volumes
BV
590
602
665
705
764
804
848
892
925
968
1,003
1,049
1,111
1,131
1,176
1,222
1,256
1,302
1,337
1,381
1,426
1,472
1,518
1,551
1,594
,626
,665
,702
,746
,789
,821
2,028
2,074
2,090
2,155
2,203
2,105
2,299
2,339
2,382
2,431
2,467
2,514
2,561
2,595
2,631
2,697
2,731
2,779
2,821
2,856
2,905
2,939
2,987
3,027
3,078
3,123
3,173
3,208
3,256
3,293
3,353
3,389
Vessel B
Flow Rate
gpm
91
91
91
NA
NA
91
91
NA
NA
NA
NA
NA
70
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
78
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
98
NA
NA
NA
NA
NA
NA
103
NA
NA
NA
98
NA
NA
103
NA
NA
NA
NA
NA
Vessel B
Service
Totalizer
gal
275,090
280,488
309,822
328,931
355,460
372,554
391,931
410,436
424,496
443,020
457,596
476,125
492,894
507,614
525,767
544,109
557,855
576,526
591,015
609,618
628,969
648,622
668,540
682,802
702,735
717,060
735,356
752,279
772,329
792,207
806,985
924,367
945,645
961,433
983,608
,006,104
,029,016
,051,005
,069,653
,089,401
,112,105
1,128,707
1,150,212
1,171,717
1,187,240
1,203,462
1,233,215
1,248,624
1,269,754
1,291,692
16,535
39,553
55,448
77,927
96,604
120,078
140,960
163,674
179,924
201,978
219,063
246,480
263,018
Cumulative
Bed Volumes
BV
575
586
647
687
742
778
819
857
887
925
956
994
,029
,060
,098
,136
,165
,204
,234
,273
,314
,355
,396
,426
,468
,498
,536
,571
,613
,655
,685
,931
,975
,008
,054
,101
,149
,195
,234
,275
,323
2,357
2,402
2,447
2,480
2,514
2,576
2,608
2,652
2,698
2,732
2,780
2,814
2,861
2,900
2,949
2,992
3,040
3,074
3,120
3,155
3,213
3,247
Combined
Backwash
Totalizer
gal
0
0
0
0
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
7,647
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
13,472
0
0
0
0
0
0
0
0
0
0
0
0
0
-------
US EPA Arsenic Demonstration Project AT Stewart, MN - Daily System Operation Log Sheet (Continued)
Week
No.
10
11
12
13
14
15
16
17
18
Day of
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Date
04/03/06 7:30 AM
04/04/06 7:30 AM
04/05/06 7:30 AM
04/06/06 7: 10 AM
04/07/06 7:30 AM
04/08/06 7:00 AM
04/09/06 7:30 AM
04/1 0/06 8:00 AM
04/1 1/06 7:30 AM
04/1 2/06 7:30 AM
04/1 3/06 7:00 AM
04/1 4/06 7:00 AM
04/1 5/06 7:50 AM
04/16/06 10: 30 AM
04/1 7/06 7: 15 AM
04/1 8/06 6:45 AM
04/1 9/06 8:00 AM
04/20/06 7:30 AM
04/21/06 7:30 AM
04/22/06 8:00 AM
04/23/06 8:00 AM
04/24/06 7:30 AM
04/25/06 9:30 AM
04/26/06 7:30 AM
04/27/06 7:30 AM
04/28/06 6:50 AM
04/29/06 8:50 AM
04/30/06 10: 00 AM
05/01/06 7:30 AM
05/02/06 8:30 AM
05/03/06 7:30 AM
05/04/06 7:30 AM
05/05/06 7: 10 AM
05/06/06 9:00 AM
05/07/06 7:30 AM
05/08/06 7:30 AM
05/09/06 8:35 AM
05/1 0/06 7:30 AM
05/1 1/06 7: 10 AM
05/1 2/06 7:00 AM
05/1 3/06 6:00 AM
05/1 4/06 7:50 AM
05/1 5/06 8: 10 AM
05/1 6/06 7:30 AM
05/1 7/06 7:30 AM
05/1 8/06 7:30 AM
05/1 9/06 7:30 AM
05/20/06 7:45 AM
05/21/06 7:15 AM
05/22/06 7:45 AM
05/23/06 7:30 AM
05/24/06 8:00 AM
05/25/06 7:00 AM
05/26/06 7:00 AM
05/27/06 7:30 AM
05/28/06 9:00 AM
05/29/06 9:30 AM
05/30/06 7:00 AM
05/31/06 10:00 AM
06/01/06 7:30 AM
06/02/06 7:00 AM
06/03/06 7:30 AM
06/04/06 8:30 AM
Well 3
Daily Op
Hours
hrs/day
2.31
2.00
2.30
1.12
1.87
1.74
1.67
1.67
1.84
1.00
2.55
1.50
2.22
1.71
1.04
2.66
2.38
2.14
2.00
2.16
1.10
2.35
2.95
2.51
2.20
1.85
1.66
1.72
2.12
1.54
1.46
2.00
3.04
1.95
2.13
2.40
1.53
2.09
2.03
2.92
1.88
1.67
1.97
2.16
2.10
2.00
2.00
0.99
1.94
2.55
2.32
2.94
2.19
3.10
3.23
2.35
2.74
4.24
2.84
3.80
3.17
3.13
3.46
Gallon
Usage
gpd
26,162
23,700
25,600
12,473
22,290
21 ,447
19,494
19,984
23,183
1 1 ,200
31,353
18,400
26,770
19,890
13,301
31,353
26,044
25,123
22,400
24,196
12,400
26,349
32,031
27,709
25,100
22,320
19,662
20,217
3,014
37,248
17,635
23,800
36,710
22,390
25,600
28,500
18,658
24,716
24,237
34,540
21,183
18,395
22,685
24,171
22,800
22,700
22,400
1 1 ,480
23,591
29,388
25,971
32,620
24,104
35,500
35,755
26,447
30,563
45,321
31,822
43,981
37,072
37,812
40,896
Average
Flowrate
gpm
189
198
186
186
198
206
195
200
210
187
205
204
201
194
213
197
183
195
187
187
188
187
181
184
190
201
197
196
NA
NA
201
198
201
191
200
198
203
197
199
197
188
183
192
187
181
189
187
193
203
192
186
185
183
191
184
187
186
178
186
193
195
201
197
Well 4
Daily Op
Hours
hrs/day
2.09
1.90
1.80
1.83
2.86
1.02
2.25
2.16
2.25
2.00
1.94
1.90
1.93
1.98
2.43
2.55
2.09
1.43
1.50
1.86
1.80
1.84
1.66
1.96
2.00
2.57
2.03
2.19
2.46
2.11
2.09
2.10
2.23
1.86
2.35
2.10
1.82
2.30
2.13
1.11
1.98
1.58
1.97
1.95
2.00
2.10
2.00
3.66
2.25
3.04
1.82
1.86
2.09
1.70
1.96
3.01
1.96
2.46
3.11
2.57
2.76
3.72
5.57
Gallon
Usage
gpd
23,414
21,400
21,000
19,876
32,647
1 1 ,643
24,784
23,216
24,511
22,200
22,264
17,500
18,942
22,140
26,140
29,413
23,477
16,647
16,600
20,963
20,900
20,528
19,477
22,800
22,300
28,594
21,969
24,127
27,684
22,752
23,791
22,900
24,034
21,368
25,280
23,500
21,720
23,354
23,527
12,185
23,583
17,094
23,770
21,600
22,700
23,700
23,000
41,567
23,694
34,384
21,423
20,571
23,374
19,600
21,845
34,541
22,237
28,800
34,667
NA
NA
39,967
59,520
Average
Flowrate
gpm
187
188
194
181
190
190
183
180
182
185
191
154
163
186
179
192
187
194
184
188
194
186
195
194
186
185
180
183
188
180
190
182
180
192
180
187
199
169
184
183
198
180
201
184
189
188
192
189
176
189
196
184
187
192
186
191
189
195
186
NA
NA
179
178
AERA LATER
Backwash
Yes/No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes
No
No
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
APU-300 Unit
Vessel A
Flow Rate
gpm
NA
91
NA
NA
NA
NA
NA
NA
86
NA
NA
NA
NA
NA
NA
99
94
NA
NA
81
NA
NA
89
NA
NA
NA
NA
NA
95
99
NA
NA
NA
NA
NA
NA
97
NA
NA
NA
NA
NA
NA
91
NA
NA
NA
NA
NA
NA
NA
88
NA
NA
NA
NA
NA
82
NA
NA
NA
NA
NA
Vessel A
Service
Totalizer
gal
295,966
316,719
344,520
361,684
385,893
403,723
427,592
450,987
474,931
493,225
517,323
523,009
542,452
567,273
585,508
611,098
639,417
660,342
683,851
706,158
725,593
749,547
778,661
802,861
824,698
847,633
871,240
895,354
917,086
939,085
962,737
986,918
1,012,484
1,036,423
1,061,862
1,086,995
1,112,269
1,134,854
1,159,259
1,178,114
1,197,538
1,220,387
1 ,244,073
1,267,795
1,291,456
1,315,427
1,338,976
1,361,859
1,386,140
1,419,448
1 ,443,607
1 ,468,540
1,482,626
1,517,547
1 ,545,234
1,578,619
1,608,016
1,640,353
NA
1,710,216
1,743,905
1,781,981
1,838,375
Cumulative
Bed
Volumes
BV
3,439
3,482
3,540
3,576
3,627
3,664
3,714
3,762
3,813
3,851
3,901
3,913
3,954
,005
,043
,097
,156
,200
,249
,295
,336
,386
,447
,497
,543
,591
,640
,691
,736
,782
,831
,882
,935
,985
5,038
5,091
5,144
5,191
5,242
5,281
5,322
5,369
5,419
5,468
5,518
5,568
5,617
5,665
5,716
5,785
5,836
5,888
5,917
5,990
6,048
6,118
6,179
6,247
NA
6,393
6,463
6,542
6,660
Vessel B
Flow Rate
gpm
NA
86
NA
NA
NA
NA
NA
NA
83
NA
NA
NA
NA
NA
NA
95
90
NA
NA
98
NA
NA
85
NA
NA
NA
NA
NA
92
96
NA
NA
NA
NA
NA
NA
94
NA
NA
NA
NA
NA
NA
90
NA
NA
NA
NA
NA
NA
NA
86
NA
NA
NA
NA
NA
81
NA
NA
NA
NA
NA
Vessel B
Service
Totalizer
gal
285,813
305,684
332,196
348,582
371,649
388,618
11,311
33,564
56,451
73,753
96,698
528,566
559,093
581,256
598,270
622,415
649,110
668,800
691,123
712,438
730,996
753,989
782,073
804,962
825,800
847,801
870,491
893,704
914,659
935,859
958,668
982,085
1,006,893
1,029,783
1,054,119
1,078,116
1,102,292
,123,876
1,147,312
,165,472
,184,169
1,206,143
1,229,005
1,251,991
1,274,925
1,298,223
1,321,122
1,343,381
1,367,029
1,399,559
1,423,099
1 ,447,450
1,470,959
1,495,225
1,522,268
1,554,878
1,583,589
1,615,279
NA
1,683,814
1,716,927
1 ,754,425
1,810,012
Cumulative
Bed Volumes
BV
3,295
3,336
3,392
3,426
3,474
3,510
3,557
3,603
3,651
3,687
3,735
3,802
3,866
3,912
3,947
3,998
4,054
4,095
4,141
4,186
4,225
4,273
4,331
4,379
4,423
4,469
4,516
4,564
4,608
4,653
4,700
4,749
4,801
4,849
4,900
4,950
5,000
5,045
5,094
5,132
5,171
5,217
5,265
5,313
5,361
5,409
5,457
5,504
5,553
5,621
5,670
5,721
5,770
5,821
5,877
5,945
6,005
6,072
NA
6,215
6,284
6,362
6,478
Combined
Backwash
Totalizer
gal
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-------
US EPA Arsenic Demonstration Project AT Stewart, MN - Daily System Operation Log Sheet (Continued)
Week
No.
19
20
21
22
23
24
25
26
27
Day of
Week
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Wed
Thu
Fri
Sat
Sun
Mon
Tue
Date
06/05/06 7: 15 AM
06/06/06 7: 15 AM
06/07/06 7:30 AM
06/08/06 8:00 AM
06/09/06 8:00 AM
06/1 0/06 9:00 AM
06/11/069:00 AM
06/1 2/06 7:30 AM
06/1 3/06 7:00 AM
06/1 4/06 7: 10 AM
06/1 5/06 7:20 AM
06/1 6/06 7:00 AM
06/1 7/06 7:30 AM
06/18/067:45 AM
06/1 9/06 7:30 AM
06/20/06 9:30 AM
06/21/06 7:00 AM
06/22/06 7:00 AM
06/23/06 7:30 AM
06/24/06 9:30 AM
06/25/06 8:40 AM
06/26/06 7:00 AM
06/27/06 7:30 AM
06/28/06 7:30 AM
06/29/06 7:00 AM
06/30/06 7:00 AM
07/01/06 8:00 AM
07/02/06 8:00 AM
07/03/06 7:00 AM
07/04/06 7:00 AM
07/05/06 7:00 AM
07/06/06 7:00 AM
07/07/06 7:30 AM
07/08/06 7:00 AM
07/09/06 8:30 AM
07/1 0/06 7:30 AM
07/1 1/06 7:30 AM
07/1 2/06 7:45 AM
07/1 3/06 7:00 AM
07/1 4/06 7:30 AM
07/1 5/06 7:30 AM
07/16/068:00 AM
07/1 7/06 7:30 AM
07/1 8/06 7:30 AM
07/1 9/06 7:00 AM
07/20/06 7:00 AM
07/21/06 7:00 AM
07/22/06 9: 10 AM
07/23/0610:10 AM
07/24/06 7: 15 AM
07/25/06 7:00 AM
07/26/06 6:20 AM
07/27/06 7:00 AM
07/28/06 7:00 AM
07/29/06 8: 15 AM
07/30/06 8:45 AM
07/31/06 6:30 AM
08/01/06 9:30 AM
WellS
Daily Op
Hours
hrs/day
2.32
2.70
2.08
3.04
3.30
2.69
2.00
2.13
2.45
2.88
1.89
2.23
1.37
3.56
1.21
3.23
2.68
2.80
3.23
4.89
0.21
2.36
2.84
2.20
1.84
2.10
2.02
3.30
2.19
2.80
3.10
2.70
4.31
3.57
2.26
5.53
2.60
4.35
6.50
3.23
2.80
4.21
3.06
3.60
5.31
2.00
3.50
3.67
3.07
3.19
3.33
2.88
3.50
4.30
3.99
7.25
2.87
3.82
Gallon
Usage
gpd
26,796
32,000
23,852
36,343
39,000
32,064
23,500
25,387
30,128
32,772
23,338
24,034
15,673
39,390
13,642
35,815
29,693
29,700
37,910
35,538
26,832
28,048
34,188
25,000
22,570
25,000
23,712
40,000
24,522
32,200
36,400
31 ,300
50,841
42,791
25,506
64,383
29,400
50,177
68,542
35,363
30,900
48,980
34,315
38,100
56,272
22,000
36,400
41,732
35,040
35,744
36,783
34,354
42,032
49,700
47,810
85,224
35,972
42,667
Average
Flow rate
gpm
192
198
191
199
197
199
196
198
205
190
206
180
190
184
188
185
185
177
195
121
NA
198
201
189
205
198
196
202
187
192
196
193
197
200
188
194
188
192
176
182
184
194
187
176
177
183
173
190
190
187
184
199
200
193
200
196
209
186
Well 4
Daily Op
Hours
hrs/day
1.69
3.70
2.08
3.43
3.30
2.02
2.10
2.35
2.35
4.07
2.09
2.64
2.84
2.28
1.92
1.85
2.12
3.00
3.23
4.15
2.18
2.47
2.16
2.60
3.68
7.90
3.84
2.40
3.23
3.70
3.40
3.40
4.31
3.47
5.27
2.71
4.40
7.62
4.65
3.33
2.90
4.90
2.14
5.80
3.37
2.10
4.80
3.49
3.07
3.30
5.96
4.11
6.42
6.70
5.42
2.84
5.08
4.80
Gallon
Usage
gpd
17,196
40,100
22,466
37,518
34,400
22,560
23,600
25,387
25,430
43,399
23,239
31,132
31,543
25,633
19,806
23,262
23,219
33,700
36,049
44,862
23,413
26,006
23,510
27,800
41,055
87,300
41,280
25,400
34,017
39,400
36,100
36,600
44,865
36,153
54,306
28,800
46,900
76,602
53,574
36,049
31,800
50,155
24,919
63,500
37,481
23,400
50,800
36,504
31,200
32,670
59,318
43,611
71,805
70,800
56,840
29,976
53,517
51,200
Average
Flowrate
gpm
170
181
180
182
174
187
187
180
180
178
186
197
185
188
172
210
182
187
186
180
179
175
182
178
186
184
179
176
175
177
177
179
173
174
172
177
178
168
192
180
183
171
194
182
185
186
176
175
169
165
166
177
186
176
175
176
176
178
AERALATER
Backwash
Yes/No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
No
No
Yes
No
No
No
No
No
Yes
No
No
No
No
No
No
No
No
Yes
No
No
No
No
Yes
No
No
No
No
Yes
No
APU-300 Unit
Vessel A
Flow Rate
gpm
NA
NA
NA
NA
95
NA
NA
NA
95
NA
NA
NA
NA
NA
NA
95
NA
NA
NA
NA
NA
NA
94
NA
NA
NA
NA
94
NA
NA
NA
NA
85
NA
NA
NA
NA
NA
NA
NA
80
NA
93
NA
73
83
81
NA
NA
81
NA
NA
NA
82
NA
NA
NA
82
Vessel A
Service
Totalizer
gal
1 ,859,633
1,896,516
1 ,920,563
1 ,956,062
1 ,993,408
2,018,564
2,042,466
2,066,750
2,092,388
2,133,607
2,157,420
2,180,588
2,205,255
2,238,756
2,256,658
2,287,962
2,312,303
2,344,847
2,378,811
2,423,121
2,448,429
2,474,481
2,501 ,625
2,531 ,793
2,557,220
2,616,173
2,651 ,423
2,681 ,050
2,714,077
2,750,262
2,786,863
2,823,623
2,865,948
2,908,966
2,953,202
2,998,101
3,038,652
3,105,202
3,117,350
3,156,849
3,186,370
3,241 ,639
3,268,449
3,320,042
3,366,506
3,388,565
3,433,666
3,473,299
3,506,408
3,537,286
3,589,635
3,626,432
3,678,340
3,734,103
3,789,942
3,847,814
3,887,370
3,931 ,228
Cumulative
Bed
Volumes
BV
6,705
6,782
6,832
6,906
6,984
7,037
7,086
7,137
7,191
7,277
7,327
7,375
7,427
7,496
7,534
7,599
7,650
7,718
7,789
7,882
7,934
7,989
8,046
8,109
8,162
8,285
8,358
8,420
8,489
8,565
8,641
8,718
8,806
8,896
8,989
9,082
9,167
9,306
9,332
9,414
9,476
9,591
9,647
9,755
9,852
9,898
9,992
10,075
10,144
10,209
10,318
10,395
10,503
10,620
10,736
10,857
10,940
11,031
Vessel B
Flow Rate
gpm
NA
NA
NA
NA
95
NA
NA
NA
96
NA
NA
NA
NA
NA
NA
95
NA
NA
NA
NA
NA
NA
92
NA
NA
NA
NA
92
NA
NA
NA
NA
81
NA
NA
NA
NA
NA
NA
NA
78
NA
91
NA
71
77
74
NA
NA
87
NA
NA
NA
89
NA
NA
NA
88
Vessel B
Service
Totalizer
gal
1,831,041
1,867,421
1,891,195
1,926,446
1,963,490
1,988,497
2,012,255
2,036,415
2,061,868
2,102,710
2,126,215
2,149,056
2,173,412
2,206,522
2,224,265
2,255,247
2,279,162
2,311,172
2,344,822
2,388,127
2,412,780
2,438,009
2,464,389
2,493,682
2,518,338
2,575,296
2,609,067
2,637,568
2,669,270
2,703,977
2,739,016
2,774,146
2,814,596
2,855,521
2,897,540
2,940,264
2,978,660
3,041,629
3,091,457
3,128,875
3,140,070
3,192,592
3,218,007
3,266,629
3,310,241
3,330,963
3,373,384
3,410,821
3,442,266
3,471,541
3,520,970
3,560,844
3,616,274
3,675,770
3,735,249
3,796,925
3,838,985
3,885,665
Cumulative
Bed Volumes
BV
6,522
6,598
6,648
6,721
6,799
6,851
6,901
6,951
7,004
7,090
7,139
7,186
7,237
7,306
7,344
7,408
7,458
7,525
7,595
7,686
7,737
7,790
7,845
7,906
7,958
8,077
8,147
8,207
8,273
8,345
8,419
8,492
8,576
8,662
8,750
8,839
8,919
9,051
9,155
9,233
9,256
9,366
9,419
9,521
9,612
9,655
9,744
9,822
9,887
9,949
10,052
10,135
10,251
10,375
10,499
10,628
10,716
10,814
Combined
Backwash
Totalizer
gal
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
-------
APPENDIX B
ANALYTICAL DATA TABLES
-------
Analytical Results from Long-Term Sampling at Stewart, MN
Sampling Date
Sampling Location
Parameter
Bed Volume (103)
Alkalinity (as
CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
TOC
PH
Temperature
DO
ORP
Total Hardness (as
CaCO3)
Ca Hardness (as
CaCO,)
Mg Hardness (as
CaC03)
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
Mg/L
02/02/06™
IN
423
1.7
0.3
<1
<0.05
1.0
27.6
7.3
6.7
8.2
11.4
1.1
-36.6
211
112
98.9
52.3
43.8
8.5
39.8
4.0
1240
1159
29.4
29.7
AC
432
1.9
0.3
<1
<0.05
0.9
25.6
4.3
7.1
8.2
11.8
7.9
250
209
113
95.4
52.4
21.3
31.1
4.2
17.0
1202
<25
541
118
AF
427
-
1.7
0.3
<1
<0.05
0.3
24.9
0.9
6.8
8.4
12.4
5.0
203
206
113
93.6
21.2
18.5
2.7
1.3
17.2
<25
<25
127
138
TB
0.7
432
-
1.7
0.3
<1
<0.05
0.03
24.1
2.0
NA™
8.2
10.9
4.8
256
214
113
101
0.3
0.2
O.1
0.9
O.1
<25
<25
3.7
3.6
02/14/06
IN
421
0.9
25.6
7.9
7.6
11.4
1.1
35.2
36.9
1144
21.3
AC
442
0.8
26.9
15
7.9
11.4
NAID)
128
33.5
1044
21.0
AF
417
-
-
-
-
-
0.3
25.7
1.4
7.9
12.4
NA|D)
166
-
22.6
<25
47.4
TA
1.2
438
-
-
-
-
-
0.03
24.4
1.7
7.9
13.1
NA|D)
175
-
0.4
<25
10.7
TB
1.1
421
-
-
0.03
25.4
1.8
7.9
13.4
NA|D)
179
0.3
<25
7.2
02/21/06
IN
419
0.9
26.3
6.5
7.6
12.9
NA|D)
294
42.7
1238
24.5
AC
419
-
-
-
0.9
25.7
15
8.3
10.5
NAID)
341
-
43.8
1205
25.4
AF
419
-
-
-
-
-
0.3
25.0
1.1
8.3
11.7
NA|D)
333
-
27.1
<25
47.8
TA
1.5
419
-
-
0.03
25.3
0.8
8.2
12.1
NA|D)
323
0.6
<25
14.2
TB
1.4
414
0.03
24.8
0.9
8.4
12.2
NAID)
321
0.5
<25
11.2
02/27/06™
IN
422
-
1.0
0.4
<1
0.05
0.9
26.5
9.2
6.3
7.4
10.6
1.3
271
226
109
117
38.7
35.6
3.2
34.2
1.4
1193
855
24.3
24.7
AC
413
-
1.1
0.4
<1
0.05
0.9
24.6
9.6
6.7
7.9
11.5
6.0
273
224
110
114
41.4
32.5
8.9
26.4
6.1
1192
<25
26.5
24.8
AF
434
1.1
0.4
<1
0.05
0.3
23.0
0.7
6.3
7.7
11.9
4.0
176
212
105
107
24.0
24.4
O.1
2.0
22.4
<25
<25
40.5
41.3
TA
1.7
418
1.1
0.4
<1
0.05
0.03
23.8
1.0
NA™
7.8
12.5
3.4
177
210
103
106
0.7
0.4
0.3
1.7
O.1
<25
<25
17.1
17.5
03/06/06
IN
419
-
-
-
-
-
0.9
24.6
7.1
7.7
10.5
1.8
300
-
39.7
120
2
24.3
AC
410
0.9
24.6
8.9
8.3
10.1
6.3
288
41.8
1185
31.4
AF
427
0.3
24.2
1.5
8.0
11.6
3.2
281
24.8
<25
37.2
TA
2.2
419
-
-
-
-
-
0.01
23.7
1.6
8.0
11.8
3.6
289
-
0.7
<25
18.2
TB
2.1
419
-
-
-
-
-
0.01
24.1
3.5
8.1
11.4
3.4
307
-
0.6
<25
20.1
(a) TOC sample bottle broke during transit.
(b) Operator recorded DO readings as percentage therefore no reading available.
(c) TT sample tap is not present. Sample taken from individual vessel for speciation week.
-------
Analytical Results from Long-Term Sampling at Stewart, MN (Continued)
Sampling Date
Sampling Location
Parameter
Bed Volume (103)
Alkalinity (as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
TOC
pH
Temperature
DO
ORP
Total Hardness (as
CaCO3)
Ca Hardness (as
CaCO3)
Mg Hardness (as
CaC03)
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
M9/L
Hg/L
Hg/L
ng/L
ng/L
Mg/L
ng/L
Mg/L
ng/L
03/14/06
IN
-
422
-
-
-
-
-
0.9
-
23.3
-
6.1
-
-
7.9
12.5
1.1
284
-
-
-
49.3
-
-
-
-
-
1157
-
-
23.0
-
-
AC
-
422
-
-
-
-
-
0.9
-
23.1
-
8.6
-
-
8.2
10.9
6.2
291
-
-
-
48.4
-
-
-
-
-
1168
-
-
24.1
-
-
AF
-
422
-
-
-
-
-
0.3
-
23
-
0.9
-
-
8.1
11.3
3.1
268
-
-
-
30.3
-
-
-
-
-
<25
-
-
33.4
-
-
TA
2.6
426
-
-
-
-
-
<0.01
-
23.3
-
0.8
-
-
8.1
10.8
3.9
212
-
-
-
0.6
-
-
-
-
-
<25
-
-
21.2
-
-
TB
2.4
426
-
-
-
-
-
<0.01
-
23.5
-
1.2
-
-
8.1
11.8
3.4
188
-
-
-
0.7
-
-
-
-
-
<25
-
-
23.4
-
-
03/21/06
IN
-
419
-
-
-
-
-
1.0
-
24.5
-
11
-
-
7.9
16.6
0.8
216
-
-
-
37.2
-
-
-
-
-
1155
-
-
44.3
-
-
AC
-
419
-
-
-
-
-
1.0
-
24.5
-
9.3
-
-
8.3
11.0
5.7
237
-
-
-
38.9
-
-
-
-
-
1139
-
-
25.0
-
-
AF
-
423
-
-
-
-
-
0.4
-
25.1
-
0.9
-
-
8.1
12.6
2.2
249
-
-
-
25.0
-
-
-
-
-
<25
-
-
31.5
-
-
TA
2.9
423
-
-
-
-
-
<0.01
-
25.1
-
0.7
-
-
8.2
11.5
2.4
168
-
-
-
0.5
-
-
-
-
-
<25
-
-
23.6
-
-
TB
2.7
423
-
-
-
-
-
<0.01
-
25.2
-
0.6
-
-
8.2
11.5
2.7
154
-
-
-
0.5
-
-
-
-
-
<25
-
-
25.8
-
-
03/28/06'"
IN
-
408
-
1.7
0.4
<1
<0.05
0.2
-
24.8
-
5.9
-
6.2
8.1
12.7
0.6
281
229
117
112
36.5
-
36.0
0.5
33.4
2.5
1096
-
412
19.8
-
22.8
AC
-
416
-
1.7
0.4
<1
<0.05
0.9
-
25
-
9.9
-
6.2
8.3
11.0
5.5
266
213
107
106
41.4
-
33.3
8.1
24.4
8.9
1176
-
<25
23.2
-
23.2
AF
-
412
-
1.6
0.4
<1
<0.05
0.4
-
-
-
1
-
6.2
8.3
11.1
4.9
195
206
102
103
30.2
-
29.2
1.0
2.9
26.4
<25
-
<25
28.0
-
28.8
TA
3.2
416
-
1.4
0.4
<1
<0.05
<0.01
-
24.3
-
0.6
-
6.1
8.3
11.1
4.7
158
209
104
105
0.5
-
0.5
<0.1
0.6
<0.1
<25
-
<25
25.3
-
26.0
04/04/06
IN
-
414
-
-
-
-
-
0.9
-
25.1
-
6.3
-
-
8.0
12.2
0.5
8.9
-
-
-
37.1
-
-
-
-
-
1077
-
-
21.5
-
-
AC
-
410
-
-
-
-
-
0.9
-
24.5
-
8.7
-
-
8.4
13.1
5.2
146
-
-
-
37.6
-
-
-
-
-
1059
-
-
22.9
-
-
AF
-
410
-
-
-
-
-
0.3
-
25.5
-
0.7
-
-
8.2
13.6
1.6
148
-
-
-
25.2
-
-
-
-
-
<25
-
-
29.5
-
-
TA
3.5
414
-
-
-
-
-
<0.0
1
-
25.2
-
0.8
-
-
8.2
14.3
2.4
140
-
-
-
0.5
-
-
-
-
-
<25
-
-
26.4
-
-
TB
3.3
414
-
-
-
-
-
<0.0
1
-
25.6
-
1.1
-
-
8.2
15.4
1.9
146
-
-
-
0.5
-
-
-
-
-
<25
-
-
28.3
-
-
(a) TT sample tap is not present. Sample taken from individual vessel for speciation week.
IN = Influent, AC = after gravity filtration; TA = after tank A; TB = after tank B; TT = after combined effluent
NA = not available.
-------
Analytical Results from Long-Term Sampling at Stewart, MN (Continued)
Sampling Date
Sampling Location
Parameter
Bed Volume (103)
Alkalinity (as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
TOC
pH
Temperature
DO
ORP
Total Hardness (as
CaC03)
Ca Hardness (as
CaCO3)
Mg Hardness (as
CaCO3)
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
M9/L
ra/L
pg/L
Hg/L
pg/L
M9/L
pg/L
Mg/L
pg/L
04/11/06ca|
IN
-
440
-
-
-
-
-
0.9
-
24.1
-
9.4
-
-
7.8
13.0
0.6
21.4
-
-
-
41.8
-
-
-
-
-
1175
-
-
23.1
-
-
AC
-
440
-
-
-
-
-
0.8
-
24.4
-
8.9
-
-
8.1
11.5
4.2
210
-
-
-
39.7
-
-
-
-
-
1179
-
-
24.2
-
-
AF
-
448
-
-
-
-
-
0.3
-
25.1
-
0.9
-
-
8.1
12.9
1.8
186
-
-
-
30.3
-
-
-
-
-
<25
-
-
31.9
-
-
TA
3.8
440
-
-
-
-
-
<0.01
-
25.1
-
1.0
-
-
8.1
14.0
1.9
168
-
-
-
0.9
-
-
-
-
-
<25
-
-
30.5
-
-
TB
3.7
435
-
-
-
-
-
<0.01
-
25.2
-
0.7
-
-
8.1
14.1
2.3
118
-
-
-
0.9
-
-
-
-
-
<25
-
-
33.2
-
-
04/18/06
IN
-
435
448
-
-
-
-
0.9
0.9
24.6
24.9
5.0
5.8
-
8.0
14.2
0.7
89.7
-
-
-
39.0
38.9
-
-
-
-
1197
1200
-
23.3
23.6
-
AC
-
444
435
-
-
-
-
0.9
0.9
25.1
25.5
8.8
8.6
-
8.4
12.7
5.0
213
-
-
-
39.1
39.6
-
-
-
-
1163
1156
-
23.8
23.8
-
AF
-
440
431
-
-
-
-
0.3
0.3
23.3
24.3
0.7
0.6
-
8.2
13.3
2.2
216
-
-
-
22.5
22.5
-
-
-
-
<25
<25
-
28.5
28.2
-
TA
4.1
444
440
-
-
-
-
0.0
0.0
25.1
24.9
0.5
0.7
-
8.2
13.8
2.9
164
-
-
-
0.6
0.6
-
-
-
-
<25
<25
-
27.9
28.5
-
TB
4.0
431
444
-
-
-
-
<0.03
<0.03
24.2
24.5
0.4
0.6
-
8.2
13.3
2.9
160
-
-
-
0.7
0.7
-
-
-
-
<25
<25
-
30.2
30.6
-
04/25/06
IN
-
423
-
1.6
0.5
<1
<0.05
0.9
-
25.9
-
4.3
-
6.2
8.1
12.6
0.6
119
205
111
94.0
39.5
-
34.1
5.4
27.9
6.2
1181
-
931
24.0
-
24.6
AC
-
415
-
1.4
0.5
<1
<0.05
0.9
-
24.6
-
7.6
-
6.2
8.4
12.1
5.1
161
214
118
96.4
43.6
-
44.9
<0.1
21.7
23.2
1277
-
<25
27.7
-
25.6
AF
-
431
-
1.3
0.4
<1
0.2
0.3
-
25.1
-
0.5
-
6.3
8.2
13.8
1.8
229
218
120
99.0
23.1
-
21.9
1.2
<0.1
21.8
<25
-
<25
30.4
-
30.9
TT
4.4
427
-
1.0
0.4
<1
0.3
<0.01
-
24.8
-
0.6
-
6.1
8.2
11.7
2.4
152
221
122
99.8
<0.1
-
<0.1
<0.1
<0.1
<0.1
<25
-
<25
34.2
-
35.1
05/02/06
IN
-
421
-
-
-
-
-
0.8
-
25.9
-
4.6
-
-
8.0
10.2
0.5
16.8
-
-
-
36.6
-
-
-
-
-
1088
-
-
22.2
-
-
AC
-
420
-
-
-
-
-
0.8
-
25.7
-
8.3
-
-
8.3
10.3
5.0
349
-
-
-
36.1
-
-
-
-
-
1063
-
-
22.6
-
-
AF
-
432
-
-
-
-
-
0.3
-
25.5
-
0.6
-
-
8.2
10.5
1.9
251
-
-
-
30.8
-
-
-
-
-
<25
-
-
29.6
-
-
TA
4.8
412
-
-
-
-
-
<0.01
-
26.2
-
0.4
-
-
8.2
10.8
2.5
198
-
-
-
0.7
-
-
-
-
-
<25
-
-
28.2
-
-
TB
4.7
412
-
-
-
-
-
<0.01
-
26.2
-
0.8
-
-
8.2
10.8
2.1
195
-
-
-
0.9
-
-
-
-
-
<25
-
-
32.3
-
-
(a) Water quality measurements taken on 04/10/06.
IN = Influent, AC = after gravity filtration; TA = after tank A; TB = after tank B; TT = after combined effluent
NA = not available.
-------
Analytical Results from Long-Term Sampling at Stewart, MN (Continued)
Sampling Date
Sampling Location
Parameter
Bed Volume (103)
Alkalinity (as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
TOC
pH
Temperature
DO
ORP
Total Hardness (as
CaC03)
Ca Hardness (as
CaCO3)
Mg Hardness (as
CaCO3)
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
M9/L
ra/L
pg/L
Hg/L
pg/L
M9/L
pg/L
Mg/L
pg/L
05/09/06'"
IN
-
410
-
-
-
-
-
0.8
-
25.5
-
4.1
-
-
8.0
11.8
1.5
78.1
-
-
-
35.5
-
-
-
-
-
1027
-
-
21.0
-
-
AC
-
419
-
-
-
-
-
0.8
-
26
-
8.3
-
-
8.3
11.0
4.8
140
-
-
-
35.9
-
-
-
-
-
1081
-
-
24.5
-
-
AF
-
423
-
-
-
-
-
0.3
-
25.9
-
0.7
-
-
8.2
11.0
2.5
170
-
-
-
21.5
-
-
-
-
-
<25
-
-
29.7
-
-
TA
5.1
423
-
-
-
-
-
<0.01
-
26.3
-
0.6
-
-
8.2
10.6
2.6
168
-
-
-
0.7
-
-
-
-
-
<25
-
-
31.2
-
-
TB
5.0
410
-
-
-
-
-
<0.01
-
26.3
-
0.7
-
-
8.2
10.5
2.7
165
-
-
-
0.8
-
-
-
-
-
<25
-
-
32.9
-
-
05/16/06
IN
-
422
-
-
-
-
-
0.9
-
26.3
-
5.5
-
-
8.0
11.0
0.8
-1.4
-
-
-
40.3
-
-
-
-
-
1311
-
-
25.1
-
-
AC
-
434
-
-
-
-
-
0.9
-
26.8
-
8.1
-
-
8.2
10.8
5.3
140
-
-
-
40.1
-
-
-
-
-
1235
-
-
25.7
-
-
AF
-
426
-
-
-
-
-
0.3
-
25.2
-
0.6
-
-
8.9
11.1
2.2
119
-
-
-
21.2
-
-
-
-
-
<25
-
-
28.5
-
-
TA
5.5
409
-
-
-
-
-
<0.01
-
26
-
0.4
-
-
8.1
10.9
2.0
112
-
-
-
0.5
-
-
-
-
-
<25
-
-
30.7
-
-
TB
5.3
422
-
-
-
-
-
<0.01
-
26.2
-
0.7
-
-
8.1
11.5
2.2
117
-
-
-
0.7
-
-
-
-
-
<25
-
-
32.0
-
-
05/24/06
IN
-
414
-
1.6
0.5
<1
<0.05
0.9
-
25.2
-
4.9
-
6.3
7.5
12.6
1.1
71.3
200
101
98.8
45.2
-
41.8
3.3
35.7
6.2
1057
-
784
20.3
-
20.7
AC
-
423
-
1.6
0.5
<1
<0.05
0.9
-
24.5
-
9.1
-
6.3
7.8
11.6
5.0
248
189
95.0
93.9
47.2
-
33.7
13.6
25.5
8.2
1019
-
<25
21.8
-
20.3
AF
-
423
-
1.5
0.5
<1
0.1
0.4
-
24.9
-
0.7
-
6.5
7.7
19.3
2.5
386
217
109
108
38.7
-
26.7
12.0
0.5
26.2
<25
-
<25
25.1
-
22.0
TT
5.8
419
-
1.2
0.5
<1
0.3
<0.01
-
25.2
-
0.7
-
6.6
7.7
11.7
2.5
150
222
110
111
1.1
-
1.0
<0.1
0.6
0.3
<25
-
<25
29.4
-
28.7
05/30/06
IN
-
424
-
-
-
-
-
0.9
-
24.5
-
4.3
-
-
8.2
10.9
1.9
265
-
-
-
35.7
-
-
-
-
-
1063
-
-
20.3
-
-
AC
-
420
-
-
-
-
-
0.9
-
24.4
-
9.7
-
-
8.5
11.5
4.9
340
-
-
-
33.6
-
-
-
-
-
983
-
-
20.3
-
-
AF
-
420
-
-
-
-
-
0.4
-
24.2
-
0.6
-
-
8.4
11.2
3.8
308
-
-
-
19.8
-
-
-
-
-
<25
-
-
21.9
-
-
TA
6.2
400
-
-
-
-
-
0.1
-
24.5
-
0.4
-
-
8.4
11.4
3.6
300
-
-
-
0.7
-
-
-
-
-
<25
-
-
24.6
-
-
TB
6.1
367
-
-
-
-
-
0.1
-
24.1
-
1.0
-
-
8.4
11.5
3.7
297
-
-
-
0.9
-
-
-
-
-
<25
-
-
26.4
-
-
CO
(a) Operator turned off potassium permanganate pump after sampling event on 05/09/06.
IN = Influent, AC = after gravity filtration; TA = after tank A; TB = after tank B; TT = after combined effluent
NA = not available.
-------
Analytical Results from Long-Term Sampling at Stewart, MN (Continued)
Sampling Date
Sampling Location
Parameter
Bed Volume (103)
Alkalinity (as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
TOC
pH
Temperature
DO
ORP
Total Hardness (as
CaC03)
Ca Hardness (as
CaCO3)
Mg Hardness (as
CaCO3)
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
M9/L
Hg/L
Hg/L
ng/L
ng/L
Mg/L
ng/L
Mg/L
ng/L
06/06/06
IN
-
422
-
-
-
-
-
1.1
-
25.7
-
15.0
-
-
8.0
10.9
1.9
316
-
-
-
42.2
-
-
-
-
-
1491
-
-
23.0
-
-
AC
-
435
-
-
-
-
-
0.8
-
25.5
-
9.9
-
-
8.2
12.1
3.8
222
-
-
-
37.4
-
-
-
-
-
1037
-
-
21.6
-
-
AF
-
431
-
-
-
-
-
0.4
-
25.4
-
0.7
-
-
8.2
11.4
4.2
203
-
-
-
28.6
-
-
-
-
-
27.4
-
-
27.6
-
-
TA
6.8
435
-
-
-
-
-
0.04
-
26.1
-
1.2
-
-
8.2
11.3
3.1
137
-
-
-
1.1
-
-
-
-
-
<25
-
-
27.2
-
-
TB
6.6
422
-
-
-
-
-
0.1
-
26.1
-
1.1
-
-
8.2
11.2
3.1
139
-
-
-
1.5
-
-
-
-
-
<25
-
-
30.6
-
-
06/13/06
IN
-
429
-
-
-
-
-
1.1
-
27.0
-
6.2
-
-
8.0
11.4
0.7
337
-
-
-
51.1
-
-
-
-
-
1104
-
-
23.5
-
-
AC
-
416
-
-
-
-
-
1.0
-
26.8
-
8.5
-
-
8.3
10.6
5.6
319
-
-
-
50.3
-
-
-
-
-
1111
-
-
24.1
-
-
AF
-
433
-
-
-
-
-
0.4
-
26.9
-
0.6
-
-
8.1
11.2
2.1
269
-
-
-
30.4
-
-
-
-
-
<25
-
-
26.5
-
-
TA
7.2
454
-
-
-
-
-
<0.03
-
27.1
-
0.5
-
-
8.1
11.6
2.5
273
-
-
-
1.1
-
-
-
-
-
<25
-
-
28.2
-
-
TB
7.0
441
-
-
-
-
-
0.04
-
27.0
-
1.0
-
-
8.1
12.6
3.0
259
-
-
-
1.9
-
-
-
-
-
<25
-
-
29.2
-
-
06/20/06
IN
-
454
-
1.8
0.6
<1
<0.05
1.0
-
28.3
-
7.6
-
NA(a)
7.9
11.2
1.1
378
237
119
117
50.9
-
44.6
6.3
40.7
3.9
1351
-
1335
25.5
-
26.1
AC
-
416
-
1.6
0.5
<1
<0.05
1.0
-
26.1
-
8.5
-
NA(a)
8.3
11.0
4.3
256
236
118
118
45.5
-
37.3
8.2
27.3
10.0
1276
-
68.5
25.3
-
25.2
AF
-
425
-
1.2
0.6
<1
0.3
0.4
-
26.6
-
0.9
-
NA(a)
8.3
11.2
2.4
190
235
118
117
29.0
-
25.8
3.2
1.3
24.5
<25
-
<25
25.5
-
24.7
TT
7.5
421
-
1.2
0.6
<1
0.5
0.05
-
27.0
-
0.9
-
NA(a)
8.1
11.4
2.7
195
240
120
119
1.4
-
1.2
0.2
0.4
0.9
<25
-
<25
28.3
-
27.6
06/27/06
IN
-
421
-
1.6
-
-
<0.05
0.9
-
26.8
-
4.6
-
-
8.0
10.1
0.7
404
-
-
-
40.6
-
-
-
-
-
1090
-
-
23.8
-
-
AC
-
417
-
1.3
-
-
<0.05
0.9
-
26.1
-
8.8
-
-
8.3
10.4
4.7
209
-
-
-
39.2
-
-
-
-
-
1061
-
-
24.2
-
-
AF
-
417
-
1.5
-
-
0.1
0.4
-
26.2
-
0.7
-
-
8.2
11.0
1.7
154
-
-
-
27.9
-
-
-
-
-
<25
-
-
26.5
-
-
TA
8.0
417
-
1.0
-
-
0.2
0.04
-
26.7
-
0.6
-
-
8.2
11.6
2.7
156
-
-
-
1.7
-
-
-
-
-
<25
-
-
29.0
-
-
TB
7.8
417
-
1.1
-
-
0.2
0.1
-
26.5
-
0.8
-
-
8.2
11.5
2.6
154
-
-
-
1.7
-
-
-
-
-
<25
-
-
30.4
-
-
Sample analysis failed laboratory QA/QC check.
IN = Influent, AC = after gravity filtration; TA = after tank A; TB = after tank B; TT = after combined effluent
NA = not available.
-------
Analytical Results from Long-Term Sampling at Stewart, MN (Continued)
Sampling Date
Sampling Location
Parameter
Bed Volume (103)
Alkalinity (as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (as SiO2)
Turbidity
TOC
pH
Temperature
DO
ORP
Total Hardness (as
CaC03)
Ca Hardness (as
CaCO3)
Mg Hardness (as
CaCO3)
As (total)
As (soluble)
As (particulate)
As (III)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
M9/L
ra/L
pg/L
Hg/L
pg/L
M9/L
pg/L
Mg/L
pg/L
07/05/06
IN
-
431
-
1.2
-
-
<0.05
0.9
-
24.9
-
5.3
-
-
8.1
11.0
1.7
311
-
-
-
46.1
-
-
-
-
-
1321
-
-
25.8
-
-
AC
-
419
-
1.2
-
-
<0.05
0.9
-
24.4
-
8.4
-
-
8.2
10.8
5.0
170
-
-
-
45.5
-
-
-
-
-
1305
-
-
26.1
-
-
AF
-
419
-
0.9
-
-
0.4
0.3
-
25.5
-
1.1
-
-
8.2
11.0
3.8
166
-
-
-
26.5
-
-
-
-
-
<25
-
-
26.1
-
-
TA
8.6
410
-
0.7
-
-
0.5
<0.03
-
25.2
-
0.8
-
-
8.2
11.1
2.6
140
-
-
-
2.7
-
-
-
-
-
<25
-
-
27.7
-
-
TB
8.4
406
-
0.9
-
-
0.6
0.05
-
24.3
-
0.6
-
-
8.2
11.7
2.9
134
-
-
-
2.1
-
-
-
-
-
<25
-
-
27.5
-
-
07/11/06
IN
-
427
419
NA
-
-
NA
0.8
0.9
25.0
25.3
4.2
5.5
-
8.0
10.9
1.0
163
-
-
-
36.7
38.7
-
-
-
-
993
1075
-
20.9
21.9
-
AC
-
423
419
NA
-
-
NA
0.9
0.9
24.6
24.1
8.6
8.6
-
8.3
11.0
7.2
172
-
-
-
38.2
39.1
-
-
-
-
1056
1076
-
21.5
22.5
-
AF
-
423
419
NA
-
-
NA
0.3
0.4
24.6
25.8
0.5
0.5
-
8.2
11.6
3.2
236
-
-
-
26.2
28.7
-
-
-
-
<25
<25
-
23.1
24.5
-
TA
9.2
419
423
NA
-
-
NA
0.1
0.1
25.8
25.2
0.5
0.6
-
8.1
12.1
3.3
229
-
-
-
2.1
2.1
-
-
-
-
<25
<25
-
25.1
25.2
-
TB
8.9
423
419
NA
-
-
NA
0.1
0.1
25.5
25.4
0.3
0.5
-
8.1
12.1
3.8
179
-
-
-
2.6
2.1
-
-
-
-
<25
<25
-
26.0
23.0
-
07/18/06
IN
-
439
-
1.6
0.5
<1
<0.05
1.1
-
25.0
-
6.9
-
6.4
8.0
10.8
1.6
343
210
116
94.3
43.4
-
39.4
4.0
32.3
7.0
1197
-
852
23.2
-
23.4
AC
-
447
-
1.9
0.5
<1
<0.05
0.9
-
24.7
-
10.0
-
6.6
8.2
11.5
5.2
288
195
96.6
98.0
43.0
-
33.9
9.1
25.6
8.3
1230
-
<25
24.7
-
24.3
AF
-
439
-
1.3
0.5
<1
0.2
0.4
-
25.0
-
1.0
-
6.5
8.2
11.0
2.7
261
224
113
110
38.4
-
26.1
12.3
0.6
25.6
<25
-
<25
23.6
-
23.5
TT
9.6
416
-
1.2
0.5
<1
0.4
0.1
-
24.8
-
0.4
-
6.5
8.2
10.8
2.5
264
206
104
102
2.3
-
3.0
<0.1
0.5
2.5
<25
-
<25
26.4
-
26.7
07/25/06
IN
-
421
-
1.7
-
-
<0.05
1.1
-
25.0
-
8.0
-
-
8.0
10.2
0.5
371
-
-
-
56.4
-
-
-
-
-
1312
-
-
23.9
-
-
AC
-
421
-
1.9
-
-
<0.05
1.1
-
25.7
-
12.0
-
-
8.3
10.8
5.0
267
-
-
-
56.9
-
-
-
-
-
1309
-
-
25.0
-
-
AF
-
425
-
1.4
-
-
<0.05
0.4
-
24.9
-
1.0
-
-
8.2
10.6
1.9
156
-
-
-
32.9
-
-
-
-
-
<25
-
-
26.1
-
-
TA"»
10.3
421
-
0.6
-
-
0.7
0.8
-
25.8
-
2.2
-
-
8.2la)
11.71"
6.2la)
137(a)
-
-
-
7.4
-
-
-
-
-
337
-
-
26.9
-
-
TB"»
10.1
417
-
0.4
-
-
1.6
1.0
-
25.6
-
3.2
-
-
8.2
11.5
5.7
175
-
-
-
9.2
-
-
-
-
-
524
-
-
27.5
-
-
Cd
(a) Water quality measurements taken at sampling location TT.
(b) 07/25/06 TA and TB samples rerun with similar results for As, Fe, and Mn
IN = Influent, AC = after gravity filtration; TA = after tank A; TB = after tank B; TT = after combined effluent
NA = not available.
-------
Analytical Results from Long-Term Sampling at Stewart, MN (Continued)
Cd
Sampling Date
Sampling Location
Parameter
BedVolume(103)
Alkalinity (as CaCO3)
Ammonia (as N)
Fluoride
Sulfate
Nitrate (as N)
Total P (as PO4)
Silica (asSiO2)
Turbidity
TOC
PH
Temperature
DO
ORP
Total Hardness (as CaCO3)
Ca Hardness (as CaCO3)
Mg Hardness (as CaCO3)
As (total)
As (soluble)
As (particulate)
As (1 1 1)
As(V)
Fe (total)
Fe (soluble)
Mn (total)
Mn (soluble)
Unit
BV
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
NTU
mg/L
S.U.
°C
mg/L
mV
mg/L
mg/L
mg/L
M9/L
M9/L
M9/L
M9/L
M9/L
M9/L
M9/L
M9/L
M9/L
08/01/06
IN
-
416
-
1.9
-
-
<0.05
1.0
-
27.8
-
5.3
-
-
8.1
10.7
0.6
111
-
-
-
52.3
-
-
-
-
-
1121
-
-
22.3
-
-
AC
-
416
-
1.6
-
-
<0.05
0.9
-
28.2
-
7.5
-
-
8.3
12.0
4.4
95.9
-
-
-
44.1
-
-
-
-
-
1070
-
-
22.9
-
-
AF
-
412
-
1.2
-
-
0.4
0.3
-
28.1
-
0.4
-
-
8.2
11.9
3.1
108
-
-
-
27.3
-
-
-
-
-
<25
-
-
24.9
-
-
TA
11.0
407
-
1.0
-
-
1.7W
0.1
-
28.3
-
0.4
-
-
8.2
11.5
2.1
88.7
-
-
-
2.8
-
-
-
-
-
<25
-
-
25.2
-
-
TB
10.8
412
-
1.0
-
-
0.3
0.1
-
28.6
-
0.3
-
-
8.2
11.7
2.2
83.9
-
-
-
3.3
-
-
-
-
-
<25
-
-
26.2
-
-
(a) 08/01/06 TA sample was rerun with similar result for nitrate
(b) Low effluent TOC levels. Results confirmed with laboratory.
IN = Influent, AC = after gravity filtration; TA = after tank A; TB = after tank B; TT = after combined effluent
NA = not available.
------- |