August 2001
NSF 01/25/EPADW395
Environmental Technology
Verification Report
Removal of Arsenic in
Drinking Water
KOCH Membrane Systems
TFC® - ULP4 Reverse Osmosis
Membrane Module
Park City, UT
Prepared by
NSF International
Under a Cooperative Agreement with
AEPA U.S. Environmental Protection Agency
ETVETVETV
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
PROGRAM ^
ETV
oEPA
U.S. Environmental Protection Agency
ETV Joint Verification Statement
NSF International
TECHNOLOGY TYPE:
REVERSE OSMOSIS MEMBRANE FILTRATION USED IN
PACKAGED DRINKING WATER TREATMENT SYSTEMS
APPLICATION:
REMOVAL OF ARSENIC IN DRINKING WATER AT PARK
CITY, UTAH
TECHNOLOGY NAME:
KOCH MEMBRANE SYSTEMS TFC® - ULP4 REVERSE
OSMOSIS MEMBRANE MODULE
COMPANY:
KOCH MEMBRANE SYSTEMS
ADDRESS:
850 MAIN STREET PHONE: (952) 470-1253
WILMINGTON, MA 01887 FAX: (952) 470-1062
EMAIL:
epplem@kochind.com
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative or improved environmental
technologies through performance verification and dissemination of information. The goal of the ETV
program is to further environmental protection by substantially accelerating the acceptance and use of
improved and more cost-effective technologies. ETV seeks to achieve this goal by providing high
quality, peer reviewed data on technology performance to those involved in the design, distribution,
permitting, purchase, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations; stakeholders groups which
consist of buyers, vendor organizations, and permitters; and with the full participation of individual
technology developers. The program evaluates the performance of innovative technologies by developing
test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests (as
appropriate), collecting and analyzing data, and preparing peer reviewed reports. All evaluations are
conducted in accordance with rigorous quality assurance protocols to ensure that data of known and
adequate quality are generated and that the results are defensible.
NSF International (NSF) in cooperation with the EPA operates the Drinking Water Treatment Systems
(DWTS) program, one of 12 technology areas under ETV. The DWTS program recently evaluated the
performance of a reverse osmosis membrane module used in package drinking water treatment system
applications. This verification statement provides a summary of the test results for the Koch Membrane
Systems TFC® - ULP4 Reverse Osmosis Membrane Module. Cartwright Olsen and Associates, LLC, an
NSF-qualified field testing organization (FTO), performed the verification testing.
01/25/EPADW395 Hie accompanying notice is an integral part of this verification statement. August 2001
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ABSTRACT
Verification testing of the Koch membrane module was conducted over a 34-day period from March 15,
2000 through April 17, 2000. The test was conducted at Park City Spiro Tunnel Water Filtration Plant in
Park City, Utah. The source water was the Spiro Tunnel Bulkhead water, which is considered a
groundwater source. Based on manufacturer's recommendations, the unit was set to operate at 150 psi
inlet pressure, a water recovery of 15%, and operated at a specific flux of 0.24-0.27 gfd/psi (25°C) during
the first days of operation. The total arsenic concentration in the feedwater averaged 60 ug/L during the
test period. The Koch membrane module reduced total arsenic to an average of 0.9 ug/L in the treated
water. The Koch membrane module reduced the dissolved arsenic in the feedwater from an average of 42
ug/L to 1.3 ug/L in the permeate (treated water). The dominant arsenic species in the Spiro Tunnel feed
water is As (V). The feedwater average concentration of Arsenic (V) was 32 ug/L and was reduced to an
average level of 0.8 ug/L in the treated water. Arsenic (III) was also rejected by the membrane, reducing
the average feedwater level from 8 ug/1 to 0.6 ug/L in the permeate. The system operated continuously
over the verification test period and achieved an average total arsenic removal of 99%. Dissolved arsenic,
which represented 70% of the arsenic in the feedwater, showed an average removal of 97%. The system
was cleaned at the end of the test period to demonstrate the cleaning procedures. There was no significant
fouling of the membrane during the verification test period operating at 15% recovery. There was a steady
decrease in specific flux over the 34-day test period from 0.27 gfd/psi (25°C) to 0.20 gfd/psi (25°C).
TECHNOLOGY DESCRIPTION
Reverse Osmosis (RO) processes are generally used to remove dissolved salts and ionic solids, such as
arsenic, sodium, chloride, and other dissolved materials from drinking water. RO membranes will also
remove particulate contaminants, but high particulate loads can lead to membrane fouling. Certain
membrane polymers can reject more than 99% of all ionic solids and have a molecular weight cut-off in
the range of 50 to 100 daltons. The Koch membrane module is a spiral wound polyamide membrane with
a fiberglass outer wrap. The molecular weight cut-off is approximately 100 daltons. RO membranes are
designed to reject dissolved salts and operate at pressures that are typically an order of magnitude higher
than membrane filtration processes designed to remove only particulate matter. RO operating pressure
requirements are a function of the concentration of the contaminants in the feedwater. Larger contaminant
levels in the water will require higher pressure to effect the separation. The Koch membrane module is
rated for a maximum pressure of 350 psi and normal design pressure of 125 psi.
The Koch membrane module is enclosed in CHAMP-440 RO Membrane Housing. Each element is 4X40
inches and has an active membrane surface of 81 ft2. The element is designed to operate at a minimum
flow rate of 3 gpm and a maximum flow rate of 10 gpm. The elements are designed for a typical water
recovery of 15% and a design specific flux of 0.18 gfd/psi at 25°C.
The verification testing was performed using a ROSY-200 pilot test unit. The test unit is a self-contained
system, housing a Gould G & L Model 25VBK 11 high pressure pump, two pressure vessels, each
containing a reverse osmosis membrane element, and all piping, wiring, and flow/pressure controls for
operation. A pre-fllter, using a 5-micron cartridge was placed in the feedwater line prior to the high
pressure pump. This pre-filter removed larger particulate matter that could foul the membranes.
The ROSY-200 pilot test unit is equipped with three way valves for use in cleaning and backwashing the
membrane. A 50-gallon cleaning tank was setup to provide a cleaning solution supply that was pumped to
the unit through a 5-micron filter. The unit was designed so that permeate and concentrate streams were
redirected back to the cleaning tank for recirculation during the cleaning process.
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VERIFICATION TESTING DESCRIPTION
Test Site
The verification testing site was the Park City Spiro Tunnel Water Filtration Plant in Park City, Utah. The
source water was the Spiro Tunnel Bulkhead water, which is considered a groundwater source under the
State of Utah source protection program. Water is developed from water bearing fissures in abandoned
silver mine tunnel. A five-foot bulkhead built approximately two miles into the tunnel holds back the
water and creates a reservoir. The water is piped to the treatment plant through a 12-inch diameter pipe.
The water is considered stable with respect to quality and quantity, and is known to contain arsenic.
Methods and Procedures
Conductivity, pH and turbidity measurements were conducted on-site, using equipment setup in the
filtration plant laboratory and in accordance with Standard Methods for the Examination of Water and
Wastewater, 20th edition, (APHA, et. al., 1998). Conductivity was monitored twice per day, while pH and
turbidity were monitored once per day. Turbidity information was also collected daily from the filtration
plant continuous in-line monitor. Temperature was recorded daily from the calibrated in-line thermometer
located on the test unit. The Silt Density Index, a measure of the quantity of suspended solids in the
feedwater, was determined on-site on seven occasions using ASTM D 4189-95. Samples for total
dissolved solids were collected twice per week and sent to the State of Utah Division of Drinking Water
Laboratory. Other analyses performed at the State of Utah laboratory included fluoride, iron, manganese,
and sulfate on a weekly basis, and alkalinity, suspended solids, silica, total organic carbon and LSI on a
monthly basis. The off-site laboratory followed test procedures as described in Methods for Chemical
Analysis of Water and Wastes (EPA, 1979), except for TOC, which was analyzed in accordance with
Standard Methods for the Examination of Water and Wastewater, 20th edition, (APHA, et. al., 1998).
Magnesium and chloride were also measured during the verification test period.
Samples of the feedwater, concentrate, and permeate were collected on a daily basis and sent to the State
of Utah Laboratory for arsenic analysis. Special on-site procedures were used to prepare the samples so
that arsenic speciation could be determined. Field procedures included collecting a total arsenic sample,
filtering an aliquot of sample for the determination of dissolved arsenic, and passing an aliquot of filtered
sample through an ion exchange resin so that the concentration of arsenic (III) and arsenic (V) could be
determined. All samples were preserved with acid mixtures described in the arsenic speciation procedure.
The daily results for total arsenic, dissolved arsenic, arsenic (III) and arsenic (V) were obtained using
ICP/MS analysis in accordance with USEPA method 200.8 as described in Methods for the
Determination of Metals in Environmental Samples Supplement I (EPA. 1994). Antimony analyses were
performed on a daily basis by the off-site laboratory using Method 200.8.
VERIFICATION OF PERFORMANCE
System Operation
The Koch membrane module was setup in accordance with the manufacturer's recommendations and
operated for a one-week period to establish optimum operating conditions. The major operating
parameters monitored during the initial operating period were specific flux, net driving pressure and
percent water recovery. Initial operating conditions were set to achieve a water recovery of 15% with an
inlet pressure of 150 psi, which gave a specific flux of 0.27 gfd/psi (at 25°C). The system operating
conditions during the initial two day period (flux stabilization period) varied slightly with the specific flux
decreasing from 0.27 to 0.25 gfd/psi (at 25°C) and the permeate flow rate dropping from 1.22 to 1.12
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gpm. No significant changes were made in the operating conditions of the system during this initial
operations period.
The unit was operated at an inlet operating pressure of 150 psi (range 144-151 psi) for the remaining 32
days of the test. The unit was considered to be stabilized after the two-day stabilization period. Inlet water
temperature was 49°F (9.44°C) based on twice-daily measurements. Flow rates for the concentrate and
permeate streams were monitored twice per day. The permeate flow averaged 1.01 gpm with a range of
0.90 to 1.12 gpm. Water recovery data calculated twice per day ranged from 13.1% to 15.4%. The twice-
daily conductivity measurements were correlated with the total dissolved solids data to obtain twice daily
TDS estimates for calculating specific flux. The specific flux slowly decreased throughout the entire test
period. The average specific flux was 0.23 gfd/psi (25°C) with a range of 0.20 to 0.25 gfd/psi (25°C)
during the main operating period.
The system was operated with a 5|i cartridge filter in the feedwater line to the system. The filter was
initially changed on an every two-day basis for the first 18 days of the test period. Following a high
turbidity measurement by the filtration plant in-line monitor, the cartridge filter was changed daily for the
remaining 16 days of the verification test.
The RO membrane elements were operated for the entire 34-day test period without shutting down for
cleaning. Membrane cleaning was performed at the end of the test period to test the cleaning process. The
unit was cleaned using 50 gallons of 2% (wt/wt) citric acid solution. The cleaning solution was circulated
through the membrane module for one hour followed by a 1 -% hour soaking time. The unit was then
rinsed with feed water for approximately 'A hour and placed back on-line. Operating data collected after
the cleaning showed that the unit returned to typical operating conditions prior to the cleaning process
with permeate flow of 1.10 gpm and a specific flux of 0.25 gfd/psi (25°C).
Water Quality Results
All of the feedwater samples, with the exception of the samples for turbidity, were collected immediately
before the membrane and after the raw water had passed through the 5-micron cartridge filter. The
feedwater from the Spiro Tunnel Bulkhead had the following average water quality during the verification
test period: TDS 543 mg/1, pH 7.31, iron 0.166 mg/1, sulfate 274 mg/1, alkalinity 147 mg/1, and
temperature 49°F (9.44°C). The turbidity, as measured before the 5 micron cartridge filter, ranged from
0.78 to 3.65 NTU with one spike to 11.83 NTU on the in-line meter. The feedwater total arsenic levels
averaged 60 ug/1. Results of the dissolved arsenic analysis showed that 70% of the arsenic present in the
feedwater was in the dissolved form. Arsenic speciation for valence states (III) and (V) showed that
arsenic (V) represented 76% of the dissolved arsenic in the source water. Antimony levels in the
feedwater averaged 8.7 ug/1.
The Koch membrane module averaged 99% removal of the total arsenic in the feedwater over the
verification test period. As shown by the data, the unit was able to produce a consistent high quality
permeate with total arsenic levels below 1 ug/1 over the range of feedwater concentrations (48.8-77 ug/1).
Total Arsenic Data Summary
Feed (|J.g/L)
Concentrate (Uft/L)
Permeate (|J.g/L)
% Rejection
Minimum
48.8
45.1
0.7
98
Maximum
77
87.9
1.0
99
Average
60
64
0.9
99
Standard Deviation
7.5
11
0.09
0.21
Confidence Interval
(58, 63)
(61,68)
(0.8, 0.9)
(99, 99)
01/25/EPADW395 The accompanying notice is an integral part of this verification statement. August 2001
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Dissolved arsenic results show that the system achieved an average rejection of 97% for dissolved arsenic
with a range of 92% to 98%. The unit was very effective in removing dissolved arsenic. The calculated
rejection percentages were influenced by a possible analytical problem at the low levels being monitored
in the permeate. Some type of contamination or interference due to the procedures used to preserve and
handle the samples for dissolved arsenic and arsenic speciation may have caused the analytical
difficulties.
Dissolved Arsenic Data Summary
Feed (|ig/L)
Concentrate (|ig/L)
Permeate (|ig/L)
% Rejection
Minimum
19.4
34.7
0.79
92
Maximum
52
61
1.5
98
Average
42
48
1.3
97
Standard Deviation
7.0
7.4
0.15
1.0
Confidence Interval
(39, 44)
(45, 50)
(1.3,1.4)
(96, 97)
The arsenic speciation results show that arsenic (V) is the predominate species present in the feedwater
with 76% of the dissolved arsenic determined to be arsenic (V). The Koch membrane module averaged
97% removal of the arsenic (V) and generated a permeate that averaged 0.8 ug/1 and had a maximum
level of 1 ug/1. The system also removed arsenic (III) to an average concentration of 0.6 ug/1.
Arsenic (V) Data Summary
Feed (|ig/L)
Concentrate (|ig/L)
Permeate (|ig/L)
% Rejection
Minimum
16.7
23.5
<0.5
94
Maximum
49.95
57.5
1
98
Average
32
40
0.8
97
Standard Deviation
8.7
8.1
0.1
1.0
Confidence Interval
(29, 36)
(37, 43)
(0.7, 0.8)
(97, 98)
Total antimony results showed that the permeate concentration was less than 3.0 ug/1 in all samples
analyzed. The unit achieved the highest possible rejection percentage (67%) that could be calculated
based on a maximum feed concentration of 9.1 ug/1 and a laboratory MDL of 3.0 ug/1.
Operation and Maintenance Results
The system ran continuously throughout the duration of the verification test (34 days). The feed pump
was shut down for five minutes each day to change the 5|i cartridge filter. Once the flows, pressures, and
water recovery conditions were established during the Initial Operations period, no adjustments were
made throughout the duration of the test. Cleaning at the end of the test was performed using manual
procedures.
There was no evidence during the test period of significant or catastrophic chemical fouling of the
membrane element. There was a steady decrease in permeate flow rate and specific flux over the 34 day
test period, which indicated that cleaning would be required soon. Mass balances using the iron and
arsenic data did indicate the possible buildup of some materials within the membrane. The cleaning at the
end of the test period was to evaluate the cleaning procedures and any effects on the membrane. The
cleaning was very effective in returning the membrane to operating conditions similar to the clean
conditions at the beginning of the test (after flux stabilization).
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The Operation and Maintenance Manual provided by Koch Membrane Systems was available for review
and to assist with on-site operations. The Manual gave a basic overview of reverse osmosis systems
operation and gave helpful information on how to troubleshoot the system.
The consumables used by the system were the prefilter cartridges and citric acid cleaning chemical. A
prefilter cartridge (5 |i, 20 inches long) was replaced daily. The citric acid cleaning chemical was
USP/FCC quality. The quantity required was 50 gallons of 2% (wt/wt) per module.
Original Signed by
Frank Princiotta for
E. Timothy Oppelt
08/15/01
Original Signed by
Gordon Bellen
08/16/01
E. Timothy Oppelt Date
Director
National Risk Management Research Laboratory
Office of Research and Development
United States Environmental Protection Agency
Gordon Bellen
Vice President
Federal Programs
NSF International
Date
NOTICE: Verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. EPA and NSF make no
expressed or implied warranties as to the performance of the technology and do not certify that a
technology will always operate as verified. The end user is solely responsible for complying with
any and all applicable federal, state, and local requirements. Mention of corporate names, trade
names, or commercial products does not constitute endorsement or recommendation for use of
specific products. This report is not a NSF Certification of the specific product mentioned herein.
Availability of Supporting Documents
Copies of the ETV Protocol for Equipment Verification Testing for Removal of Arsenic
(Chapter One General Requirements) dated March 30, 2000, ETV Protocol for
Equipment Verification Testing for Removal of Inorganic Chemical Constituents (Test
Plan: Reverse Osmosis for the Removal of Inorganic Contaminants) dated February 25,
2000, the Verification Statement, and the Verification Report (NSF Report
#01/25/EPADW395) are available from the following sources:
(NOTE: Appendices are not included in the Verification Report. Appendices are
available from NSF upon request.)
1. Drinking Water Systems ETV Pilot Manager (order hard copy)
NSF International
P.O. Box 130140
Ann Arbor, Michigan 48113-0140
2. NSF web site: http://www.nsf.org/etv (electronic copy)
3. EPA web site: http://www.epa.gov/etv (electronic copy)
01/25/EPADW395 The accompanying notice is an integral part of this verification statement. August 2001
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Environmental Technology Verification Report
Removal of Arsenic from Drinking Water
Koch Membrane Systems
TFC® -ULP4 Reverse Osmosis
Membrane Element Module
Prepared for
NSF International
Ann Arbor, MI 48105
Prepared by
Cartwright, Olsen and Associates, LLC
19406 East Bethel Blvd.
Cedar, Minnesota 55011
(612) 434-1300
Under a cooperative agreement with the U.S. Environmental Protection Agency
Jeffrey Q. Adams, Project Officer
National Risk Management Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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Notice
The U.S. Environmental Protection Agency (EPA) through its Office of Research and
Development has financially supported and collaborated with NSF International (NSF) under
Cooperative Agreement No. CR 824815. This verification effort was supported by the Drinking
Water Treatment Systems Pilot operating under the Environmental Technology Verification
(ETV) Program. This document has been peer reviewed and reviewed by NSF and EPA and
recommended for public release.
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Foreword
The following is the final report on an Environmental Technology Verification (ETV) test
performed for NSF International (NSF) and the United States Environmental Protection Agency
(EPA) by Cartwright, Olsen & Associates, LLC (COA) in cooperation with Koch Membrane
Systems. The test was conducted during March and April of 2000, at the Spiro Tunnel Water
Treatment Plant, Park City, Utah.
Throughout its history, the EPA has evaluated the effectiveness of innovative technologies to
protect human health and the environment. A new EPA program, the Environmental Technology
Verification Program (ETV) was developed to verify the performance of innovative technical
solutions to environmental pollution or human health threats. ETV was created to substantially
accelerate the entrance of new environmental technologies into the domestic and international
marketplace. Verifiable, high quality data on the performance of new technologies is made
available to regulators, developers, consulting engineers, and those in the public health and
environmental protection industries. This encourages more rapid availability of approaches to
better protect the environment.
The EPA has partnered with NSF, an independent, not-for-profit testing and certification
organization dedicated to public health, safety and protection of the environment, to verify
performance of small drinking water systems that serve small communities under the Drinking
Water Treatment Systems (DWTS) Pilot. A goal of verification testing is to enhance and
facilitate the acceptance of small package drinking water treatment equipment by state drinking
water regulatory officials and consulting engineers while reducing the need for testing of
equipment at each location where the equipment's use is contemplated. NSF will meet this goal
by working with manufacturers and NSF-qualified Field Testing Organizations (FTO) to conduct
verification testing under the approved protocols. Cartwright, Olsen and Associates is one such
FTO.
NSF is conducting the DWTS Pilot with participation of manufacturers, under the sponsorship of
the EPA Office of Research and Development, National Risk Management Research Laboratory,
Water Supply and Water Resources Division, Cincinnati, Ohio. It is important to note that
verification of the equipment does not mean that the equipment is "certified" by NSF or
"accepted" by EPA. Rather, it recognizes that the performance of the equipment has been
determined and verified by these organizations for those conditions tested by the FTO.
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Table of Contents
Section Page
Verification Statement VS-i
Title Page i
Notice ii
Foreword iii
Table of Contents iv
Abbreviations and Acronyms viii
Operational Formulae x
Acknowledgments xiv
Chapter 1 - Introduction 1
1.1 ETV Purpose and Program Operation 1
1.2 Testing Participants and Responsibilities 1
1.2.1 N SF Internati onal 2
1.2.2 Field Testing Organization 2
1.2.3 Manufacturer 3
1.2.4 Analyti cal Lab oratory 3
1.2.5 U.S. Environmental Protection Agency 3
1.2.6 Park City Municipal Corporation, Spiro Tunnel Water Treatment Plant 4
1.3 Verification Testing Site 4
1.3.1 Water Source 4
1.3.2 Effluent Di scharge 7
1.4 Arsenic Chemistry 7
1.4.1 Health Concerns 8
1.4.2 Regulatory 8
Chapter 2 - Equipment Description and Operating Processes 10
2.1 Equipment Description 10
2.2 Operating Process 17
2.3 Equipment Capabilities 19
Chapter 3 - Methods and Procedures 22
3.1 Experimental Design 22
3.1.1 Objectives 22
3.1.2 Equipment Characteristics 22
3.1.3 Water Quality Data Collection and Analysis 23
3.2 Recording Data 24
3.3 Communications, Logistics And Data Handling Protocol 24
3.3.1 Objectives 25
3.3.2 Procedures 25
3.3.2.1 Log Books 25
3.3.2.2 Photographs 25
3.3.2.3 Chain of Custody 25
3.3.2.4 Spreadsheets 25
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Table of Contents, continued
Section Page
3.4 Recording Statistical Uncertainty 26
3.5 Verification Testing Schedule 26
3.6 Field Operations Procedures 26
3.6.1 Equipment Operations 27
3.6.1.1 Operations Manual 27
3.6.1.2 Analytical Equipment 27
3.6.2 Initial Operations 27
3.6.2.1 Flux 28
3.6.2.2 Net Driving Pressure 28
3.6.2.3 Percent Water Recovery 29
3.7 Verification Task Procedures 29
3.7.1 Task 1 - Membrane Operation 29
3.7.1.1 Water Recovery 29
3.7.1.2 Applied Pressure 30
3.7.1.3 Prefilter Replacement Frequency 30
3.7.2 Task 2 - Cleaning Efficiency 30
3.7.3 Task 3 - Finished Water Quality 33
3.7.4 Task 4 - Data Handling Protocol 33
3.8 QA/QC Procedures 34
3.8.1 Instruments with Daily QA/QC Verifications 34
3.8.1.1 pH meter 34
3.8.1.2 Conductivity Monitor 34
3.8.2 In-Line Thermometer 34
3.8.3 In-Line Pressure Gauges 34
3.8.4 In-Line Flow Meters 35
3.8.5 Turbidity Meters 35
3.8.6 Tubing and Fittings 35
3.8.7 Off-Site Analysis of Chemical Samples 35
3.8.7.1 Organic Parameters (Total Organic Carbon) 35
3.8.7.2 Inorganic Samples 35
3.8.8 SDI Measurements 36
Chapter 4 - Results and Discussion 37
4.1 Introducti on 37
4.2 Initial Operations Results 37
4.2.1 Water Recovery 37
4.2.2 Operating Pressure 37
4.3 Verification Testing Results and Discussion 38
4.3.1 Task 1 - Membrane Operation 38
4.3.2 Task 2 - Cleaning Efficiency 46
4.3.3 Task 3 - Finished Water Quality 49
4.4 Results of Equipment Characterization 72
4.4.1 Qualitative Factors 72
4.4.1.1 Susceptability to Change in Environmental Conditions 72
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Table of Contents, continued
Section Page
4.4.1.2 Operational Reliability 73
4.4.1.3 Equipment Safety 73
4.4.2 Quantitative F actors 74
4.4.2.1 Electical Power 74
4.4.2.2 Consumables 74
4.4.2.3 Waste Disposal 74
4.4.2.4 Length of Operating Cycle 75
4.5 QA/QC Results 75
4.5.1 In-Line Thermometer 75
4.5.2 Conductivity Monitor 75
4.5.3 Pressure Gauges 75
4.5.4 F1 ow Monitoring 75
4.5.5 pH Meter 76
4.5.6 Turbidity Instruments 76
4.5.7 Tubing and Fittings 76
4.5.8 Off-Site Analysis of Chemical Samples 76
4.5.8.1 Organic Parameters (Total Organic Carbon) 76
4.5.8.2 Inorganic Samples 77
4.5.9 SDI Measurements 77
4.5.10 Arsenic Speciation and Analysis 77
Chapter 5 - References 78
Table Page
Table 1-1: Historical Spiro Tunnel Bulkhead Water Untreated Quality Parameters 7
Table 1-2: Selected Inorganic Arsenic Compounds 8
Table 2-1: KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module Characteristics. 11
Table 3-1: Analytical Data Collection Schedule 23
Table 3-2: Operational Data Collection Schedule 24
Table 4-1: Total Dissolved Solids Summary 39
Table 4-2: Total Dissolved Solids, Conductivity, and TDS/Conductivity Ratio vs. Time 40
Table 4-3: TDS to Conductivity Ratio Summary 40
Table 4-4: Specific Flux Data versus Time 42
Table 4-5: Specific Flux Data Summary of AM and PM Data (gfd/psi) 42
Table 4-6: Feedwater SDI Measurements 44
Table 4-7: Turbidity Readings vs. Time 46
Table 4-8: Membrane Element System Cleaning Data 47
Table 4-9: Operating Data After Cleaning 48
Table 4-10: Module Performance After Cleaning 48
Table 4-11: Total Arsenic Readings 52
Table 4-12: Total Arsenic Data Summary 53
Table 4-13: Dissolved Arsenic Data 55
Table 4-14: Dissolved Arsenic Data Summary 56
Table 4-15: Arsenic (III) Data 58
Table 4-16: Arsenic (IE) Data Summary 58
Table 4-17: Arsenic (V) Data 60
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Table of Contents, continued
Table Page
Table 4-18: Arsenic (V) Data Summary 60
Table 4-19: Percentage of Various Arsenic Species Based on Summary Average Values 62
Table 4-20: Summary of Total and Dissolved Arsenic Mass Balances 63
Table 4-21: Antimony Concentration in Feed, Concentrate and Permeate Streams 65
Table 4-22: Antimony Summary Data 66
Table 4-23: pHData 67
Table 4-24: pH Data Summary 67
Table 4-25: Iron Concentrations 69
Table 4-26: Estimated Mass of Iron Retained in the Module 69
Table 4-27: Weekly Analytical Parameters 72
Figure Page
Figure 1-1: Schematic of Spiro Tunnel Water Filtration Plant 6
Figure 2-1: ROSY - 200 Testing Unit 12
Figure 2-2: Conventional vs. Crossflow Filtration 17
Figure 2-3: Reverse Osmosis 18
Figure 2-4: Process Flow Diagram 21
Figure 4-1: Variation of Average Specific Flux Data vs. Time 43
Figure 4-2: Feedwater SDI Measurements vs. Time 44
Figure 4-3: Total Arsenic Concentration vs. Time 53
Figure 4-4: Dissolved Arsenic Concentrations vs. Time 56
Figure 4-5: Arsenic (III) Concentration vs. Time 59
Figure 4-6: Arsenic (V) Concentration vs. Time 61
Figure 4-7: Antimony Concentration vs. Time 66
Figure 4-8: pH Measurements over Testing Period 68
Photographs Page
Photograph #1-Membrane Element Module Test Unit showing prefilter housings and high
pressure pump 13
Photograph #2-Membrane Element Module Test Unit showing prefilter housings and high
pressure pump 14
Photograph #3-Membrane Element Module Test Unit showing feed end of module 15
Photograph #4-Membrane Element Module Test Unit showing permeate and concentrate end
module 16
Photograph #5-CIP unit used for cleaning membrane element modules 32
Appendices
A. Historical Water Quality Data
B. Manufacturer's Specification Sheets and O&M Manual
C. Arsenic Speciation Procedure
D. Laboratory Analytical Reports
E. State of Utah Laboratory QA/QC Plan
F. Certificates of Calibration
G. On-Site Logbook
H. Speciation Filter Disks
I. QA/QC Procedures, Data and Discussion
vii
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Abbreviations and Acronyms
ASTM American Society for Testing and Materials
°C Celsius degrees
cfu Colony forming unit(s)
CIP Clean in place
COA Cartwright, Olsen & Associates, LLC
CV Curriculum Vitae
EPA U.S. Environmental Protection Agency
ESWTR Enhanced Surface Water Treatment Rule
ETV Environmental Technology Verification
FOD Field Operations Document
ft2 Square foot (feet)
FPT Female Pipe Thread
FTO Field Testing Organization
gfd Gallon(s) per day per square foot of membrane area
gpm Gallon(s) per minute
HPC Heterotrophic plant count bacteria
ICR Information Collection Rule
Jt Permeate flux
Jlm Transmembrane flux
Jem Specific flux
Kg Kilogram(s)
L Liters
LMD Liters per day per square meter of membrane area
LSI Langelier Saturation Index
|i Micron(s)
MDL Minimum Detection Level
m2 Square meter(s)
m3/d Cubic meter(s) per day
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
[j,g/L Microgram(s) per liter (ppb)
mgd Million gallon(s) per day
mg/L Milligram(s) per liter
min Minute(s)
mL Milliliter(s)
Modular System A packaged functional assembly of components for use in a drinking water
treatment system or packaged plant that provides a limited form of treatment
of the feedwater(s) and which is discharged to another packaged plant or the
final step of treatment to the distribution system.
MPN Most probable number
NSF NSF International, formerly known as National Sanitation Foundation
NIST National Institute of Standards and Technology
NTU Nephelometric turbidity unit(s)
P; Pressure at inlet of membrane module
P0 Pressure at outlet of membrane module
viii
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Pp
Permeate pressure
Ptm
Transmembrane pressure
PLC
Programmable Logic Controller
ppb
Parts per billion (|lg/L)
psi
Pound(s) per square inch
PVC
Polyvinyl chloride
PVR
Performance Verification Report
Qf
Feed flow
Qp
Permeate flow
QA
Quality assurance
QC
Quality control
RO
Reverse osmosis
s
Membrane surface area
scfm
Standard cubic feet per minute
sec
Second(s)
SWTR
Surface Water Treatment Rule
T
Temperature
TC
Total coliform bacteria
TDS
Total dissolved solids
TOC
Total organic carbon
TSS
Total suspended solids
USP
United States Pharmacopoeia - pharmaceutical grade chemicals
UV-254
Ultraviolet light absorbance at 254 nanometers
WEF
Water Environment Federation
WHO
World Health Organization
IX
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Operational Formulae
Permeate: Water produced by the RO membrane process.
Feedwater: Water introduced to the membrane element.
Permeate Flux: The average permeate flux is the flow of permeate divided by the surface area
of the membrane. Permeate flux is calculated according the following formula:
QP
= f
Where:
Jt = permeate flux at time t (gpd, L/(h-m2))
Qp = permeate flow (gpd, L/h)
S = membrane surface area (ft2, m2)
It should be noted that only gfd and LMD are considered acceptable units of for this testing plan.
Net Driving Pressure: For this test, a temperature conversion chart provided by the
manufacturer was used for all temperature correction. Net Driving Pressure is the total average
pressure available to force water through the membrane into the permeate stream. Net driving
pressure is calculated according to the following formula:
NDP =
{Pf + Pc)
L 2 -1
Pp-An
Where:
NDP = net driving pressure for solvent transport across the membrane (psi, bar)
Pf = feedwater pressure to the feed side of the membrane (psi, bar)
Pc = concentrate pressure on the concentrate side of the membrane (psi, bar)
Pp = permeate pressure on the treated water side of the membrane (psi, bar)
An = osmotic pressure (psi)
x
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Osmotic Pressure Gradient: The term osmotic pressure gradient refers to the difference in
osmotic pressure generated across the membrane barrier as a result of different concentrations of
dissolved salts. The following equation provides an estimate of the osmotic pressure across the
semi-permeable membrane through generic use of the difference in total dissolved solids (TDS)
concentrations on either side of the membrane:
Where:
An
(TDSf+TDSc)
2
TDSr
1 psi
100 Vf
An
TDSf
TDSC
TDS„
= osmotic pressure (psi)
= feedwater total dissolved solids (TDS) concentration (mg/L)
= concentrate TDS concentration (mg/L)
= permeate TDS concentration (mg/L)
Note that the different proportions of monovalent and multivalent ions composing the TDS will
influence the actual osmotic pressure, with lower unit pressures resulting from multivalent
species. The osmotic pressure ratio of 1 psi per 100 mg/L is based upon TDS largely composed
of sodium chloride or other monovalent ions. In contrast, for TDS composed of multivalent ions,
the ratio is closer to 0.5 psi per 100 mg/L TDS.
In this test, since specific conductivity was measured twice a day and TDS measured (by
evaporation) once a week, to be more accurate, conductivity was used in the daily osmotic
pressure calculations, from which daily Net Driving Pressures and Specific Fluxes were
calculated. The following equation is based on conductivity values:
An =
(Condf+Condc)
- Cond„
I psi
100 Vf
K
Where:
An = Osmotic pressure (psi)
Cond/= Feedwater conductivity (microsiemens/cm)
Condc= Concentrate conductivity (microsiemens/cm)
Condc = Permeate conductivity (microsiemens/cm)
K = Multiplier based on average TDS/conductivity ratios
A multiplier (K) was empirically developed to convert the daily conductivity readings to osmotic
pressure readings. This multiplier is more completely described and defined in 4.3.1.
XI
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Specific Flux: The term specific flux is used to refer to permeate flux that has been normalized
for the net driving pressure. The equation used for calculation of specific flux is given by the
formula provided below. Specific flux is usually calculated with use of flux values that have
been temperature-adjusted to 25 °C:
Jtm
Jt
NDP
Where:
Jtm = specific flux
NDP = net driving pressure for solvent transport across the membrane (psi, bar)
Jt = permeate flux at time t (gfd, LMD). Temperature-corrected flux values should be
employed.
Water Recovery: The recovery of feedwater as permeate water is given as the ratio of permeate
flow to feedwater flow:
% System Recovery = 100
Qp
Qf
Where:
Qf= feedwater flow to the membrane (gpm, L/h)
Qp = permeate flow (gpm, L/h)
Solute Rejection: Solute rejection is controlled by a number of operational variables that must
be reported at the time of water sample collection. Bulk rejection of a targeted inorganic
chemical contaminant may be calculated by the following equation:
% Solute Rejection = 100
Cf-Ct
Cf
Where:
Cf= feedwater concentration of specific constituent (mg/L)
Cp = permeate concentration of specific constituent (mg/L)
Xll
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Solvent and Solute Mass Balance: Calculation of solvent mass balance was performed during
Task 1 in order to verify the reliability of flow measurements through the membrane.
Calculation of solute mass balance across the membrane system was performed as part of Task 3
in order to estimate the concentration of limiting salts at the membrane surface.
Qf = Qp+Qc
QfCf = QpCp + QcCc
Where:
Qf = feedwater flow to the membrane (gpm, L/h)
Qp = permeate flow (gpm, L/h)
Qc = concentrate flow (gpm, L/h)
Cf= feedwater concentration of specific constituent (mg/L, |ig/L)
Cp = permeate concentration of specific constituent (mg/L, |ig/L)
Cc= concentrate concentration of specific constituent (mg/L, |ig/L)
Xlll
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Acknowledgments
The Field Testing Organization, Cartwright, Olsen & Associates (COA), was responsible for all
elements in the testing sequence, including collection of samples, calibration and verification of
instruments, data collection and analysis, data management, data interpretation and the
preparation of this report.
Cartwright, Olsen & Associates, LLC
19406 East Bethel Blvd.
Cedar, Minnesota 55011
Phone: (612) 854-4911
Fax: (612) 854-6964
e-mail: cartwrightconsul@cs.com
Contact Person: Peter Cartwright, P.E.
The laboratory that conducted the analytical work of this study was:
State of Utah
Department of Health
Division of Laboratory Services
46 Medical Drive
Salt Lake City, Utah 84113-1105
Phone: (801) 536-4204
Fax: (801) 615-5311
Contact: Larry P. Scanlan, Environmental Scientist in
The Manufacturer of the Equipment was:
Koch Membrane Systems
850 Main Street
Wilmington, Massachusetts 01887-3883
Phone: (952) 470-1253
Fax: (952)470-1062
E-mail: epplem@kochind.com
Contact Person: Madalyn Epple, Sales Manager, Midwest Region
COA wishes to thank NSF International, especially Mr. Bruce Bartley, Project Manger, and Ms.
Carol Becker and Ms. Kristie Wilhelm, Environmental Engineers for providing guidance and
program management.
NSF wishes to thank Mr. Dale Scherger, Environmental Consultant, Scherger Associates, for
providing technical guidance.
Ms. Madalyn Epple, Koch Membrane Systems, is to be commended for providing the treatment
system and the excellent technical and product expertise.
xiv
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COA is especially indebted to the following individuals at the Spiro Tunnel Water Filtration
Plant: Mr. John A. Lind, Assistant Public Works Director, Mr. Richard W. Hilbert, Assistant
Public Superintendent, Mr. Leo Williams for his invaluable assistance in monitoring and sample
collection speciation, and Mr. Jay Glazier and Mr. Scott Clayburn for their assistance to Mr.
Williams.
Mr. Larry Scanlan, Environmental Scientist, State of Utah, Department of Environmental
Quality, Division of Drinking Water, deserves special recognition for obtaining and regenerating
the anion resin used for arsenic speciation. Dr. Zenon Pawlak, Chief of the Radiochem and
Metals Lab, Division of Laboratory Services, was invaluable in his coordination of all laboratory
analyses and processing of the resulting data. Mr. Wayne Pierce, Director of the Bureau of
Environmental Chemistry and Toxicology, Division of Laboratory Services, is thanked for his
able supervision of all analytical activities.
xv
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Chapter 1
Introduction
1.1 ETV Purpose and Program Operation
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative or improved
environmental technologies through performance verification and dissemination of information.
The goal of the ETV Program is to further environmental protection by substantially
accelerating the acceptance and use of improved and more cost-effective technologies. ETV
seeks to achieve this goal by providing high quality, peer reviewed data on technology
performance to those involved in the design, distribution, permitting, purchase, and use of
environmental technologies.
ETV works in partnership with recognized standards and testing organizations; stakeholders
groups which consist of buyers, vendor organizations, and permitters; and with the full
participation of individual technology developers. The program evaluates the performance of
innovative technologies by developing test plans that are responsive to the needs of
stakeholders, conducting field or laboratory (as appropriate) testing, collecting and analyzing
data, and preparing peer reviewed reports. All evaluations are conducted in accordance with
rigorous quality assurance protocols to ensure that data of known and adequate quality are
generated and that the results are defensible.
NSF International (NSF) in cooperation with the EPA operates the Drinking Water Treatment
Systems (DWTS) Pilot, one of 12 technology areas under ETV. This DWTS Pilot evaluated
the performance of the Koch Membrane Systems TFC®-ULP4 Reverse Osmosis Membrane
Element Module, which is a membrane filtration element used in package drinking water
treatment system applications. The verification test focused on determining the capability of the
membrane element to remove total and dissolved arsenic from drinking water. This document
provides the verification test results for the Koch Membrane Systems TFC®-ULP4 Reverse
Osmosis Membrane Element Module (Koch membrane module).
1.2 Testing Participants and Responsibilities
The ETV testing of the Koch membrane module was a cooperative effort between the following
participants:
NSF International
Cartwright, Olsen & Associates, LLC
Koch
State of Utah Division of Drinking Water Laboratory
U.S. Environmental Protection Agency
Park City Municipal Corporation, Spiro Tunnel Water Filtration Plant
The following is a brief description of each ETV participant and their roles and responsibilities.
1
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1.2.1 NSF International
NSF is a not-for-profit testing and certification organization dedicated to public health safety
and the protection of the environment. Founded in 1946 and located in Ann Arbor, Michigan,
NSF has been instrumental in the development of consensus standards for the protection of
public health and the environment. NSF also provides testing and certification services to
ensure that products bearing the NSF Name, Logo and/or Mark meet those standards. The EPA
partnered with the NSF to verify the performance of drinking water treatment systems through
the EPA's ETV Program.
NSF provided technical and primary quality oversight of the verification testing. NSF arranged
an inspection of the field analytical and data gathering and recording procedures on April 17
and 18, 2000. NSF also reviewed of the Field Operations Document (FOD) to assure its
conformance with the pertinent ETV generic protocol and test plan. NSF also conducted a
review of this report and coordinated the EPA and technical reviews of this report.
Contact Information:
NSF International
789 N. Dixboro Rd.
Ann Arbor, MI 48105
Phone: (734) 769-8010
Fax: (734) 769-0109
Contact: Bruce Bartley, Project Manager
E-mail: bartley@nsf.org
1.2.2 Field Testing Organization
Cartwright, Olsen & Associates (COA), a Limited Liability Company, conducted the
verification testing of the Koch membrane module. COA is an NSF-qualified Field Testing
Organization (FTO) for the ETV DWTS Pilot.
The FTO was responsible for conducting the verification testing which covered a total of 34
days. The FTO provided all needed logistical support, established a communications network,
and scheduled and coordinated activities of all participants. The FTO determined that the
testing location and feed water conditions were such that the verification testing could meet its
stated objectives. The FTO prepared the FOD, oversaw the testing, managed, evaluated,
interpreted and reported on the data generated by the testing, as well as evaluated and reported
on the performance of the technology.
COA and the Spiro Tunnel Water Filtration Plant staff conducted the on-site analyses and data
recording during the testing. Peter Cartwright, P.E. of COA, provided oversight of the daily
tests.
Contact Information:
Cartwright, Olsen & Associates, LLC
2
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19406 East Bethel Blvd.
Cedar, Minnesota 55011
Contact Person: Peter Cartwright, P.E., Project Manager
Phone: (612) 854-4911
Fax: (612)854-6964
E-mail: cartwrightconsul@cs.com
1.2.3 Manufacturer
The treatment system is manufactured by Koch Membrane Systems (KMS), a manufacturer of
membrane separation products to municipal and industrial water users. Koch Membrane
Systems is located in Wilmington, MA.
KMS was responsible for supplying a field-ready RO membrane element module equipped with
all necessary components as defined in 2.1 Equipment Description. KMS also supplied the CIP
unit for this verification testing. KMS was responsible for providing logistical and technical
support as needed as well as providing technical assistance to COA during operation and
monitoring of the equipment undergoing field verification testing.
Contact Information:
Koch Membrane Systems
850 Main Street
Wilmington, Massachusetts 01887-3883
Contact: Madalyn Epple, Sales Manager, Midwest Region
Phone: (952)470-1253
Fax: (952)470-1062
E-mail: epplem@kochind.com
1.2.4 Analytical Laboratory
The State of Utah Division of Drinking Water Laboratory performed all chemical analyses.
These analyses were made under the direct supervision of Larry P. Scanlan, Environmental
Scientist in.
Contact Information:
State of Utah Division of Drinking Water Laboratory
Contact: Larry P. Scanlan, Environmental Scientist in
Phone: (801) 536-4204
Fax: (801) 615-5311
E-mail: lscanlan@dep.state.ut.us
1.2.5 U.S. Environmental Protection Agency
The EPA through its Office of Research and Development has financially supported and
collaborated with NSF under Cooperative Agreement No. CR 824815. The DWTS Pilot
3
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operating under the ETV Program supported this verification effort. This document was peer
reviewed and reviewed for technical and quality content by the EPA.
1.2.6 Park City Municipal Corporation, Spiro Tunnel Water Filtration Plant
Park City Municipal Corporation personnel performed non-supervisory labor associated with the
operation and monitoring of equipment under direct supervision of Peter Cartwright. These
activities included collection of operating data, and collection of analytical samples and
speciation of arsenic samples.
Contact Information:
Park City Municipal Corporation
445 Marsac Avenue
P.O. Box 1480
Park City, Utah 84060
Public Works Director: Jerry Gibbs, P.E.
Phone: (435) 615-5310:
Fax (435) 615-4904
The address of the testing site is:
Spiro Tunnel Water Filtration Plant
1884 Three Kings Drive
Park City, Utah 84060
Contact: Rich Hilbert
Phone: (435) 615-5321:
Fax (435) 658-9022
1.3 Verification Testing Site
The site selected for challenge testing of the Koch membrane module was the Park City Spiro
Tunnel Water Filtration Plant, 1884 Three Kings Drive, Park City, Utah 84060.
The Park City Municipal Corporation has direct access to Spiro Tunnel Bulkhead water. This
water source was used for verification testing. A schematic of the Spiro Tunnel Water Filtration
Plant is attached (Figure 1-1).
1.3.1 Water Source
The Spiro Tunnel Bulkhead source is considered a groundwater source under the State of Utah
source protection program. It is located at N40° 41' 20.8" and Will0 31' 25.0". Water is
developed from water bearing fissures in an abandoned silver mine tunnel. At approximately
13,600 feet into the tunnel, a five-foot high bulkhead has been constructed to hold back a
quantity of water. This water exits the tunnel through a 12" diameter pipe at a flow rate of 1,150
gpm and enters the treatment plant that is located about 300 yards away. The tunnel is located
1,000 feet or more under remote unoccupied forest in a mountainous region, and the tunnel
4
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entrance is approximately 50 feet below the bulkhead. There is no use of manmade chemicals on
the ground above this source.
The water source used for this test is known as the Spiro Tunnel Bulkhead source, and is stable
with respect to quality and quantity. Because this water source contains arsenic, for the
municipal supply, it is currently diluted with the treatment plant finished water to form a blend
that meets the present arsenic standard. For this test, only the untreated, unblended Spiro Tunnel
Bulkhead supply was used.
The existing treatment plant was built in February, 1993, has nominal capacity of 1,000 gpm, and
is designed to remove iron, manganese and arsenic from the raw water. This source is one of five
active sources serving the municipality: 2 tunnels, 2 deep wells, and a spring. The water system
serves 6,500 residents, and as much as 20,000 people per day during the winter season.
Spiro Tunnel Bulkhead water quality before treatment is listed in Table 1-1. These data are
historical and not ETV verified. This table is a summary of water quality data contained in
Appendix A.
Influent water quality to the KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module
was verified during both the initial operations period and during the verification test period. The
analytical results showing the influent water quality are presented in Chapter 4.
5
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Table 1-1: Historical Spiro Tunnel Bulkhead Untreated Water Quality
Parameter
Minimum
Maximum
pH
7.3
8.2
Total Dissolved Solids (mg/L)
520
660
Total Arsenic (ug/L)
4
225
Turbidity (NTU)
1
4
Total Alkalinity
140
152
(mg/L as CaC03)
Total Hardness
420
680
(mg/L as CaC03)
Total Iron (mg/L)
0.07
2.7
Calcium (mg/L as Ca)
106
160
Chloride (mg/L)
1
10
Sulfate (mg/L)
260
450
Manganese (ug/L)
5
30
Antimony (ug/L)
6
<100
Beryllium (ug/L)
<1
5
Cadmium (ug/L)
<1
<24
Cyanide (ug/L)
<2
5
Nitrite (N02) (mg/L)
<0.01
<0.02
Nitrate (N03) (mg/L)
<0.02
8.15
Selenium (ug/L)
<1
<5
Thallium (ug/L)
<2
<500
Mercury (ug/L)
<0.2
<1.1
1.3.2 Effluent Discharge
Concentrate water generated during the verification testing was quantified, sampled and
discharged to the Snyderville Sewer Improvement District. A discharge permit was not required.
1.4 Arsenic Chemistry
Arsenic is the 20th most abundant element in the earth's crust and is a component of over 245
minerals. Because the physical appearance of arsenic resembles that of a metal, it is classified as
7
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a metalloid and is located in group V of the Periodic Table. It readily forms both oxide and
sulfide compounds in the environment.
Arsenic enters the environment as the result of both manufacturing and natural processes.
Arsenic trioxide (As203) is formed during smelting operations and has created significant air and
land pollution problems. Arsenic also is released through the burning of certain fossil fuels and
volcanic eruptions.
In natural waters, soluble arsenic is virtually always present in the oxidation states of either
+3(HI) or +5(V) valence. An organic species (methylated) has been detected; however,
concentrations of this organic compound rarely exceed lppb and it is considered of little or no
significance as a drinking water contaminant.
In oxygenated waters, the As (V) valence is dominant, existing in the anionic forms of H^AsCV1,
HAs04 2 and As04"3. In waters containing little or no oxygen (anoxic), As (III) exists in the
nonionic form, H3As03 below a pH of 9.22, and the anionic form, H2As03~ at a pH above 9.22.
Table 1-2 lists the properties of selected inorganic arsenic compounds.
Table 1-2: Selected Inorganic Arsenic Compounds
Property
Arsenic
Arsenic Trioxide
Sodium Trioxide
Sodium Arsenate
Synonyms
Arsenic black,
colloidal arsenic,
gray arsenic
Arsenic oxide, arsenious
acid, arsenious oxide,
white arsenic
Disodium arsenate,
sodium biarsenate,
arsenic acid disodium
salt
Arsenious acid
sodium salt, sodium
metaarsenite
Chemical formula
As
As203 (As^)
Na2HAs04
NaAs02
Molecular weight
74.92
197.84
185.91
129.91
Valence state
0
3
5
3
Water Solubility
Insoluble
Soluble
37 g/L at 20°C
101 g/lat 100°C
Soluble
Very Soluble
1.4.1 Health Concerns
Arsenic has significant notoriety as a poison, even featured in a stage play, "Arsenic and Old
Lace". Recent studies have indicated that arsenic in drinking water is more dangerous than
previously thought, with risks to exposure comparable to that of radon and second hand tobacco
smoke. In humans, ingested arsenic can cause liver, lung, kidney, bladder and skin cancers.
Arsenite [As(III)] is significantly more toxic than arsenate [As(V)].
1.4.2 Regulatory
The USEPA MCL (Maximum Contaminant Level) for arsenic in drinking water was 50 ppb (50
ug/L) prior to January 22, 2001. The arsenic MCL was lowered to 10 ug/L in a rule promulgated
8
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on January 22, 2001. Data had been under review by the USEPA for several years prior to issuing
the new standard. On March 20, 2001, EPA announced that they were proposing to withdraw the
new arsenic standard and seek an independent review of the science behind the standard and the
costs associated with implementing the new rule. The USEPA indicated that they believe that the
arsenic standard needs to be revised and lowered below the current 50 ug/L level, but that they
need to review if it is necessary to set the standard as low as 10 ug/1. The World Health
Organization (WHO) has established a provisional arsenic limit of 10 ug/L.
The U.S. Geological Survey has prepared a map that identifies the location and concentration of
arsenic contaminated groundwater sites in the United States. This map can be accessed on
www.usgs.gov.
EPA information on arsenic can be accessed on www.epa.gov/safewater/arsenic.html.
9
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Chapter 2
Equipment Description and Operating Processes
2.1 Equipment Description
The characteristics of the Koch membrane module are described in Table 2-1. Data sheets for
this element are included in Appendix B.
The element was enclosed in an UltraTec Champ-440 membrane pressure vessel. The Membrane
Pressure Vessel is part of the KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module.
The verification testing of the KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module
was performed on a skid mounted ROSY-200 pilot test unit, equipped with a Goulds G & L
pump, model 25VBK11, with a 5 HP motor, operating on 230/460 voltage and drawing 13
amperes. The ROSY-200 pilot test unit is illustrated in Figure 2-1 and in the following
photographs.
The manufacturer claims that the KMS TFC®-ULP4 Reverse Osmosis Membrane Element
Module is capable of achieving a minimum of 98% total arsenic removal from raw water
supplied during operation at a flux of 21.6 gfd (879 Lmd) at a pressure of 150 psi and recovery of
15% at 25°C, and containing as much as 225 micrograms/liters of total arsenic. The manufacturer
claims to achieve a minimum of 98% TDS reduction when operated under the same conditions
on a feed water TDS of 1500 mg/1 or less.
For this verification testing, the KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module
was operated at approximately 15% recovery, meaning that 15% of the feedwater flow rate
would pass through the membrane and become permeate; the remaining 85% of the feedwater
flow rate exits the membrane element as the concentrate stream.
A 5 micron cartridge filter was installed before the feed pump to the Koch membrane module.
This pretreatment filter is not part of the basic Koch membrane module. However, it is well
recognized that RO Membranes typically require some type of pretreatment equipment to protect
the membranes from suspended solids or turbidity spikes. The exact nature of the pretreatment
process or equipment will be highly site specific depending on the water source and the
variability of the source water. For this installation the manufacturer selected a 5 micron
disposable cartridge filter as the pretreatment device.
Among the relevant factors in the verification process are costs associated with the KMS TFC®-
ULP4 Reverse Osmosis Membrane Element Module. Operating conditions were recorded to
allow reasonable prediction of performance under other, similar conditions. The specific
parameters included power and consumable (such as prefilter cartridge) supply requirements,
waste disposal, budget for chemical cleaning, and the length of operation cycle.
10
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Table 2-1: KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module
Characteristics
Parameter
Value
Membrane
Manufacturer
Koch Membrane Systems
Membrane Element Module Number
TFC®-ULP4
Size of Element Used (in)
4x40
Active Membrane Surface Area per Element (ft2)
81
Active Surface Area of Equivalent 8"x40" (ft2)
365
Molecular Weight Cut-Off (daltons)
100
Membrane Material Construction
TFC
Membrane Hydrophobicity
Hydrophilic
Reported Membrane Charge
Negative
Spacer Thickness (in)
0.031
Design Pressure (psi)
125
Design Flux at Design Pressure (gfd)
22.9
Variability of Design Flux (%)
+20/-15
Design Specific Flux (gfd/psi) at 25°
0.183
Standard Testing Recovery (%)
15
Standard Testing pH
7.5
Standard Testing Temperature (°C)
25
Design Cross-Flow Velocity (ft/s)
0.36ft/sec (i 15 gfd, 15% recovery
Maximum Flow Rate to an Element (gpm)
10
Minimum Flow Rate to an Element (gpm)
3
Required Feed Flow to Permeate Flow Ratio
10:1 (10% recovery)
Single Element Recovery (%)
15
Rejection of Reference Solute and Conditions of Test
98.5% rejection, 2000 mg/L NaCl @ 125
psi (applied)
Variability of Rejection of Reference Solute (%)
+/-5
Acceptable Range of Operating Pressure (psi)
0-175
Acceptable Range of Operating pH Values
4-11
Acceptable Range of short term cleaning pH
2.5-11
Typical Pressure Drop over a Single Element (psi)
5
Maximum Permissible SDI
5
Maximum Permissible Turbidity (NTU)
1
Chlorine/Oxidant Tolerance (mg/L)
<0.1
Suggested Cleaning Procedures
See Section 4.3.2 and App. B
11
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in
O
4>
•~
S
0/j
12
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Photograph 1: Membrane Element Module Test Unit showing prefilter housing and high pressure pump
-------
Photograph 2: Membrane Element Module Test Unit showing prefilter housing and high pressure pump
-------
Photograph 3: Membrane Element Module Test Unit showing feed end of module
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Photograph 4: Membrane Element Module Test Unit showing permeate and concentrate end of module
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2.2 Operating Processes
The pressure membrane technologies of microfiltration, ultrafiltration, nanofiltration and reverse
osmosis are widely used in water treatment applications ranging from potable water production
to ultrapure water purification.
In particular, membrane technologies possess certain properties which make them unique when
compared to other solid/liquid separation operations. These include:
• Continuous process, resulting in automatic and uninterrupted operation
• Low energy utilization involving neither phase nor temperature changes
• Modular design - no significant size limitations
• Minimal moving parts with low maintenance requirements
• No effect on form or chemistry of contaminants
• Discrete membrane barrier to ensure physical separation of contaminants
• No chemical additions required to effect separation
Membrane technologies are among the most versatile water treatment processes with regard to
their ability to effectively remove the widest variety of contaminants at the lowest costs. Simply
put, these technologies are continuous filters. The form of contaminant removed is a function of
membrane polymer selection and its pore size.
The development in filtration technology known as "crossflow" or "tangential flow" filtration
allows for continuous processing of liquid streams. In this process, the bulk solution flows over
and parallel to the filter medium and exits the system as concentrate. Under pressure, a portion
of the water in the bulk solution is forced through the filter medium (membrane) becoming
"permeate". Turbulent flow of the bulk solution across the surface minimizes the accumulation
of particulate matter on the filter surface and facilitates continuous operation of the system.
Figure 2-2 compares the crossflow mechanism with conventional filtration.
Permeate
Figure 2-2: Conventional vs. Crossflow Filtration
17
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Reverse osmosis is the crossflow filtration process which produces the highest quality permeate
of any pressure driven membrane technology. Certain polymers will reject more than 99% of all
ionic solids, and have molecular weight cut-offs in the range of 50 to 100 daltons. Figure 2-3
illustrates the rejection process in reverse osmosis.
Reverse Osmosis
Salts Macromolecules
•5§*. MEMBRANE
\v.\-
•iy.
•gv
Mjj Water
' i
Figure 2-3: Reverse Osmosis
RO membranes reject salts utilizing a mechanism that is not fully understood. Some experts
endorse the theory of pure water preferentially passing through the membrane; others attribute it
to the effect of surface charges of the membrane polymer on the polarity of the water
immediately adjacent to the membrane surface. Monovalent salts are not as highly rejected from
the membrane surface as multivalent salts; however, the high rejection properties of thin film
composite RO membranes exhibit very little difference in salt rejection characteristics. In all
cases, the greater the range of contaminant removal the higher the pressure requirement needed to
effect this separation. In other words, reverse osmosis, which separates the widest range of
contaminants, requires an operating pressure, which is an order of magnitude higher than
microfiltration, which removes only suspended solids.
The removal characteristics of reverse osmosis membranes are always based on a percentage of
the salts in the feed stream layer immediately adjacent to the membrane surface. The actual
concentration of salts in this layer is dependent upon a number of factors such as the
concentration of salts in the feed stream, system recovery, concentration polarization effects and
turbulent flow though the membrane element.
The water passage through the reverse osmosis membrane (to generate permeate) is known as
"flux". It is a function of applied pressure, water temperature and the osmotic pressure of the
solution under treatment. Flux rate is expressed as GFD (gallons per square foot per day) or
LMD (liters per square meter per day). Increasing the applied pressure will increase the permeate
rate, however, a high flow rate of water through the membrane will tend to promote more rapid
fouling. Membrane element manufacturers usually provide limits with regard to the maximum
applied pressures to be used as a function of feedwater quality and other factors.
18
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2.3 Equipment Capabilities
The purpose of this test was to verify the performance of the Koch membrane module in a formal
and comprehensive manner to offer state and local public health professionals an opportunity to
evaluate the system for specific arsenic removal applications.
The KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module has a rated NaCl removal
capability of 98% (+/-5). Since reverse osmosis membranes will typically remove multivalent
ions to a greater degree than monovalent ions and because two of the three As(V) forms in the
feed water are multivalent, it is reasonable to assume that the removal of arsenic in this supply
would be at least 98%.
As water recovery is increased, the concentration of salts within the concentrate steam increases
exponentially. For example, at 15% recovery, the concentration of salts exiting the membrane in
the concentrate stream is approximately 18% higher than in the feed stream; at 50% recovery, the
concentration is 100% higher; while at 80% recovery, the concentration is 500% higher.
This increased salts concentration effect can have adverse effects upon membrane performance in
two areas: fouling (a) and osmotic pressure (b).
a. As salts become more concentrated within the membrane element, certain
sparingly soluble species may precipitate and foul the membrane surface. In
most cases, precipitation of these species can be minimized by adding anti-
scalants or by pH adjustment, but it does present a potential design problem in
the application of reverse osmosis technology to drinking water treatment.
b. Osmotic pressure (An) is the thermodynamic resistance of a solute/solvent
system to solvent passage through the membrane. In other words, the higher
the ionic concentration of a stream, the greater its osmotic pressure and the
higher the pumping pressure required to produce permeate at a reasonable
flow rate. Osmotic pressure effects can be illustrated by the desalination of
seawater by reverse osmosis. A pumping pressure of approximately 400 psi is
required to generate any permeate flow. For practical purposes, a pumping
pressure of 800-1000 psi is required on seawater supplies to generate a
reasonable permeate rate.
The osmotic pressure of a solution is a function of both the specific solute and its concentration;
however, the osmotic pressure estimation of 1 psi/lOOppm for monovalent salts and V2
psi/lOOppm for multivalent salts can be safely applied.
Because salts concentrations increase as recovery is increased, for high TDS water, high recovery
systems require higher pumping pressure, thereby imposing design limitations, with a maximum
practical pressure limit of 1,000 psi.
For the Park City Spiro Tunnel Bulkhead water supply, the maximum recorded TDS level of 670
would, under worst case conditions, have an osmotic pressure of 6.7 psi, and at a total system
19
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recovery as high as 50%, result in a concentrate osmotic pressure of just over 13 psi. This is
insignificant in this case, and can be easily accommodated in the selection of the feed (high
pressure) pump.
A significant advantage of membrane processes over traditional water treatment technologies is
that they will also reduce the concentration of other ionic contaminants as well as high molecular
weight organic compounds and suspended solids.
In the Spiro Tunnel Bulkhead water supply, the maximum total arsenic concentration measured
to date was 225 |ig/L, however, this level was not detected during this verification (maximum
total arsenic during the test period was 77 |ig/L). The USEPA MCL, prior to January 22, 2001
was 50 |ig/L. On January 22, 2001 a new MCL of 10 ug/L was promulgated. This new standard
is currently under review by USEPA.
This module also reduced the concentrations of TDS, total hardness, sulfate and antimony in this
water supply, allowing them to meet the recommended or statutory regulatory limits, which had
been exceeded for these parameters in one or more historical readings.
During the one-month verification testing period, significant changes in the quality of the Spiro
Tunnel Bulkhead water supply were not encountered; however, reverse osmosis membrane
technology is very tolerant of water quality variations. For example, if the TDS were to increase
from 660 to 6600 mg/L, the osmotic pressure would increase to 66 psi, and, at the current
operating pressure of 150 psi, the permeate would drop by 44%. No other effect on system
performance would be expected, and the permeate rate could be recovered by increasing the
pump pressure by 66 psi.
The following Figure 2-4 is the process flow for the verification test.
20
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Feed
Water ^
5^
Prefilter
Cartridge
2.
Pump
2.
KMS TFC -ULP4
Reverse Osmosis
Membrane Element
Module
2.
t Permeate
Sample Port
Feedwater Sample Port |
Concentrate Sample Port -
Note: Turbidity measurements were made before
the prefilter. All other feedwater samples were
collected after the prefilter.
To
Wastewater
Treatment
Symbol Legend:
9
Pressure Gauge
Thermometer
Flow Control Valve
B
Flow Meter
Sample Tap
Figure 2-4: Process Flow Diagram
The greatest single cause of membrane element failure is excessive fouling - the accumulation of
suspended or precipitated solids on the membrane surface to such an extent as to inhibit water
passage through the membrane and into the permeate stream. Providing sufficient pretreatment
and utilizing sound system design principles can minimize fouling; however, it cannot be
prevented. As a result, virtually all reverse osmosis systems eventually require chemical cleaning
as part of the routine preventive maintenance.
21
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Chapter 3
Methods and Procedures
3.1 Experimental Design
This verification study was developed to provide accurate information regarding the performance
of the Koch membrane module. Because of the unpredictability of environmental conditions and
mechanical equipment performance, this document should not be viewed in the same light as
scientific research conducted in a controlled laboratory setting.
3.1.1 Objectives
The verification testing was undertaken to evaluate the performance of the KMS TFC®-ULP4
Reverse Osmosis Membrane Element Module for arsenic reduction. Specifically evaluated were
Koch Membrane Systems' stated equipment capabilities and equipment performance for the
removal of arsenic to help communities meet the future MCL. Total dissolved solids, antimony,
and several other constituents were tested to evaluate the rejection capability of the equipment for
these parameters.
An overall evaluation of the operational requirements of the KMS TFC®-ULP4 Reverse Osmosis
Membrane Element Module was undertaken as part of this verification. This evaluation was
qualitative in nature. The manufacturer's Operations and Maintenance (O&M) manual and
experiences during the daily operation were used to develop a subjective judgment of the
operational requirements of this system. The O&M manual is attached to this report as Appendix
B.
Verification testing also evaluated the maintenance requirements of the KMS Module. Not all of
the maintenance requirements were necessary to be implemented due to the short duration of the
testing cycle. The O&M manual details various maintenance activities and their frequencies.
This information, as well as experience with common pieces of equipment (i.e., pumps, valves,
etc.) was used to evaluate the maintenance requirements.
3.1.2 Equipment Characteristics
The qualitative, quantitative and cost factors of the tested equipment were identified, in so far as
possible, during the verification testing. The relatively short duration of the testing cycle created
difficulty in reliably identifying some of these factors. The qualitative factors examined during
the verification were operational aspects of the KMS TFC®-ULP4 Reverse Osmosis Membrane
Element Module; for example, susceptibility to changes in environmental conditions, operational
requirements and equipment safety, as well as other factors that might impact performance. The
quantitative factors examined during the verification testing process were costs associated with
the system. Especially important were power; consumable (such as filter cartridge) supply
requirements; cost of operation and waste disposal; budget for preventive maintenance; and the
length of operation cycle. The operating conditions were recorded to allow reasonable prediction
of performance under other, similar conditions. Also noted and reported were any occasional,
anomalous conditions that might require operator response. It is important to note that the
22
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information presented and discussed herein are for the KMS TFC®-ULP4 Reverse Osmosis
Membrane Element Module. This module operated at a specific flux of 0.20-0.27 gfd/psi at
25°C. Costs may change under other operating conditions.
3.1.3 Water Quality Data Collection and Analysis
The water quality characteristics that were recorded and analyzed are listed in Table 3-1, below.
Table 3-1: Analytical Data Collection Schedule
Sampling
Standard
Parameter
Frequency
Test Stream
Method
Location
pH
1/day
Feed, perm., conc.,
4500H+
on-site
Temperature
2/day
Feed
2550B
on-site
Conductivity
2/day
Feed, perm., conc.
2510B
on-site
TDS
2/week
Feed, perm., conc.
2540C
lab
Alkalinity
1/month
Feed, perm., conc.
2320B
lab
LSI
1/month
Feed, perm., conc.
-
lab
Turbidity
1/month
Feed, perm., conc.
2130B
on-site
TSS
1/month
Feed, perm., conc.
EPA 160.2
lab
Silica
1/month
Feed, perm., conc.
EPA 370.1
lab
TOC
1/month
Feed, perm., conc.
5310B
lab
SDI
1/month
Feed
ASTMD 4189-95
on-site
Fluoride
1/week
Feed, perm., conc.
4500C
lab
Iron
1/week
Feed, perm., conc.
EPA 200.7
lab
Manganese
1/week
Feed, perm., conc.
EPA 200.7
lab
Sulfate
1/week
Feed, perm., conc.
EPA 375.2
lab
Antimony
1/day
Feed, perm., conc.
EPA 200.8
lab
Arsenic (total)
1/day
Feed, perm, conc.
EPA 200.8
lab
Arsenic (dissolved)
1/day
Feed, perm, conc.
EPA 200.8
lab
Arsenic III
1/day
Feed, perm., conc.
EPA 200.8
lab
Arsenic V
1/day
Feed, perm., conc.
EPA 200.8
lab
Analytical samples were collected daily from the feed, concentrate and permeate streams and
speciated in order for the State Laboratory to measure total arsenic, dissolved arsenic, As in and
As V, as well as antimony. The arsenic speciation procedure is detailed in Appendix C; it
involved filling 3 containers as follows: bottle A - as collected (for total arsenic); bottle B -
filtered through 0.45)1 filter (for dissolved arsenic); bottle C - (for arsenic (HI)) part of the
filtered sample processed though an ion exchange resin to remove ionic arsenic, which is
assumed to be all As (V). Arsenic (V) concentration was calculated as dissolved arsenic minus
the arsenic (HI).
Daily samples were taken beginning on March 15, during Initial Operations and through April
17, when the test was completed. (Total test period = 34 days).
Table 3-1 lists the continuous, daily, and semi-weekly water quality analyses that were recorded.
Daily on-site analyses were recorded in the On-site Logbook and Laboratory Notebook; semi-
weekly analyses were recorded in the On-site Logbook and also recorded on separate laboratory
23
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report sheets. These data are summarized in Chapter 4 and the analytical reports are attached to
this report as Appendix D.
3.2 Recording Data
The chemical parameters and operating data were maintained in the On-site Logbook and
transferred to computer spreadsheets. All readings were manually logged.
The conductivity results for the feedwater, permeate, and concentrate streams were used to
calculate the ionic strength of the feedwater and concentrate streams, as well as osmotic pressure
gradient across the membrane on a daily basis. These data were converted to TDS equivalent
data. Osmotic pressure gradient values were then used for calculation of net driving pressure and
specific flux on a daily basis. Mass balances for specified water quality parameters were also
calculated at least once per week.
Operational data were collected and recorded for each day of the testing cycle. The operational
parameters and frequency of the readings are listed in Table 3-2 below.
Table 3-2: Operational Data Collection Schedule
Parameter Frequency
1. permeate flow rate (gpm) 2 per day
2. concentrate flow rate (gpm) 2 per day
3. feed flow rate (1+2) (gpm) 2 per day
4. element inlet pressure (psi) 2 per day
5. element outlet pressure (psi) 2 per day
6. element recovery (1/(1 + 2) x 100) (percent) 2 per day
7. conductivity (feed) 2 per day
8. conductivity (permeate) 2 per day
9. conductivity (concentrate) 2 per day
10. feed temperature (°F) 2 per day
11. osmotic pressure* {An) (psi) 2 per day
12 power consumption (kwh) 2 per day
* Based on conductivity readings.
3.3 Communications, Logistics and Data Handling Protocol
Documentation of study events was facilitated through the use of logbooks, photographs, data
sheets and chain of custody forms. Data handling is a critical component of any equipment
evaluation testing. Care in handling data ensures that the results are accurate and verifiable.
Accurate sample analysis is meaningless without verifying that the numbers are being entered
into spreadsheets and reports accurately and that the results are statistically valid.
The data management system used in the verification testing program involved the use of
computer spreadsheet software and manual recording methods for recording operational
parameters. The following describe how data were managed for each parameter.
24
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3.3.1 Objectives
The objective was to tabulate the collected data for completeness and accuracy, and to permit
ready retrieval for analysis and reporting. In addition, the use of computer spreadsheets allowed
manipulation of the data for arrangement into forms useful for evaluation. A second objective
was the statistical analysis of the data as described in the "NSF/EPA ETV Protocol for
Equipment Verification Testing for Arsenic Removal" (EPA/NSF 2000), and in section 3.4 of
this report.
3.3.2 Procedures
The above data handling procedures were used for all aspects of the verification test. Procedures
existed for the use of the log books used for recording the operational data, the documentation of
photographs taken during the study, the use of chain of custody forms, the gathering of in-line
measurements, entry of data into the customized spreadsheets and the method for performing
statistical analyses.
3.3.2.1 Log Books
Data were collected by COA in bound notebooks and on computer generated charts from the
appropriate testing instruments. There was a single field notebook containing all on-site
operating data that remained on site and contained instrument readings, on-site analyses and any
comments concerning the test run with respect to either the nature of the feedwater or the
operation of the equipment.
Each page of the notebook was sequentially numbered and identified as Koch ETV Test. Each
completed page was signed by the on-duty FTO staff. Errors were crossed out with a single line
and initialed. Deviations from the FOD were noted in the notebook, whether by error or by a
change in the conditions of either the test equipment or the water conditions. The notebook
included a carbon copy of each page. The original notebook was stored on-site, and the carbon
copy sheets retained by COA. This not only eased referencing of the original data, but also
offered protection of the original record of results.
3.3.2.2 Photographs
Photographs were logged into the field notebook. These entries included time, date, and identity
of the photographer.
3.3.2.3 Chain of Custody
Original chain of custody forms traveled with the samples from the test site to the Laboratory
(copies of which are attached as Appendix D). This is more completely described in 3.7.4.
3.3.2.4 Spreadsheets
A COA technician entered data into a computer spreadsheet program (Microsoft® Excel) on a
daily basis from the logbook and from all available analytical reports. A back-up copy of the
25
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computer data was maintained off site. The database for the project was set up in the form of
custom-designed spreadsheets. All data from the Laboratory Notebook and the On-site Logbook
were entered into the appropriate spreadsheet. All recorded calculations were checked at this
time. Following data entry, the spreadsheet was printed out and the printout was checked against
the handwritten data sheet. Corrections were noted on the hard copies and corrected on the
screen, and then a corrected version of the spreadsheet was printed out. Each step of the
verification process was initialized by the COA operator or engineer performing the entry or
verification step.
Computer data were transferred by the physical transfer of data discs.
3.4 Recording Statistical Uncertainty
Statistical 95% confidence calculations were performed for arsenic (all species), antimony,
specific flux, pH, TDS and TDS/Conductivity ratio data. These parameters are considered
important operational indicators. Sampling requirements are noted in the work plan below. The
formula used for confidence calculations follows:
confidence interval = X ± tn-Y |_ix (S /-JTi)
~2
Where
X = sample mean
S = standard deviation
N = number of measurements in data set
t = distribution value with n-1 degrees of freedom
a = the significance level defined for 95% confidence as: 1- 0.95 = 0.05.
According to the 95% confidence interval approach, the a term is defined to have the value
of 0.05, thus simplifying the equation for the 95% confidence interval in the following
manner:
95% confidence interval = X ± fn_i q 975 (S / Vft)
3.5 Verification Testing Schedule
The verification testing commenced on March 15, 2000, and the test unit ran without interruption
until April 17, 200. Operating data were recorded and analytical samples collected twice a day
through April 16 as well as the morning of April 17, 2000. During this entire period, the unit
was shut down for less than 5 minutes per day to change the 5|i prefilter cartridges.
The cleaning efficiency task was performed on April 17, 2000.
3.6 Field Operations Procedures
In order to ensure data validity, the specific procedures detailed in the Field Operations
Document Environmental Technology Verification of the Koch Membrane Systems TF(fs-ULP4
26
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Reverse Osmosis Membrane Element Module for the Removal of Arsenic from Drinking Water
were followed. This field operations document was based the NSF/EPA approved protocols for
test plan development, EPA/NSF ETV Protocol of Equipment Verification Testing for Arsenic
Removal, Chapter 1 - Requirements for All Studies, dated January 10, 2000 and EPA/NSF ETV
Protocol for Equipment Verification Testing for Removal of Inorganic Constituents, Chapter 2 -
Removal by Reverse Osmosis or Nanofiltration, dated February 25, 2000. This ensured the
accurate documentation of both water quality and equipment performance. Strict adherence to
these procedures resulted in verifiable performance of the equipment.
3.6.1 Equipment Operations
The operating procedure for the Koch membrane module is described in the Operations Manual
(Appendix B). Analytical procedures are described in the State of Utah Division of Drinking
Water Laboratory Quality Assurance Plan (Appendix E).
3.6.1.1 Operations Manual
The Operations Manual for the Rosy 200 pilot test unit was housed on-site and is attached to this
report as Appendix B. Additionally, operating procedures and equipment descriptions are
described in detail in Chapter 2 of this report.
3.6.1.2 Analytical Equipment
The following analytical equipment was used on-site during the verification testing:
• A Hach 21 OOP portable turbidimeter (serial number 000100024023) was used for benchtop
turbidity analyses.
• Pressure gauges were Ametek 4 V2" glycerin-filled and calibrated. There were four
gauge connections on the system, one on each side of the 5|i prefilter cartridges (0-60
psig), one on the inlet side of the membrane module (0-200 psig) and one on the outlet
side of the module (0-200 psig).
• An in-line NIST traceable Tel-Tru thermometer was used for the measurement of
temperature.
• Flowmeters - because of the poor accuracy of the panel mounted flowmeters on the
test unit, all flow rates were measured utilizing the "bucket and stopwatch" method.
• Conductivity readings were taken with a Myron Ultrameter Model 6P (serial #6 EVAL 1),
which was calibrated by the manufacturer in March, 2000.
• Certification of calibration for the above instruments is in Appendix F.
3.6.2 Initial Operations
Initial operations allowed CO A to refine the unit's operating procedures and to make operational
adjustments as needed to successfully treat the source water. No adjustment to the FOD was
necessary as a result of the initial operations. The Koch membrane module was operated for
approximately one week (until the start of the verification testing) to establish the optimum
treatment scheme.
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The major operating parameters examined during initial operations were specific flux, net driving
pressure and percent water recovery of the treatment unit.
3.6.2.1 Flux
Permeate production capacity of a membrane system is usually expressed as flux. Flux is the
water flow rate through the membrane divided by the surface area of the membrane. Flux is
calculated from the permeate flow rate and membrane surface area and is expressed as gfd. The
surface area of the KMS membrane used for the verification testing was 81ft2 . It is customary to
refer to flux normalized to 25°C (77°F). Lower temperatures increase the viscosity of water and
decrease the flow of permeate produced through a given membrane area.
Manufacturers of reverse osmosis membrane element modules usually provide graphs or charts
of a "Temperature Correction Factor" (TCF) as a function of water temperature. These are based
on the equation:
TCF = Q25/Qt=ex
Where:
TCF
Q25
Qt
e
x
K
t
= Temperature Correction Factor
= permeate flow rate @ 25° C (77° F)
= permeate flow rate @ temperature t (°C)
= 2.71828
= K
1
273 + t
v
1
/
298
= constant based on the membrane polymer
= water temperature (°C)
For the Koch membrane module, K=3100. KMS provides a chart for calculating TCF in
Appendix B; however, it was considered to be more accurate to use the equation to calculate the
TCF. For a temperature of 49° F (9.4° C), TCF= 1.8. This figure was used to normalize the
permeate rates to 25° C (77° F) for specific flux calculations.
Because permeate rate (and flux) are affected by the pressure applied to the membrane, another
important parameter of the membrane system is specific flux. Specific flux is calculated by
dividing the normalized flux of the system by the net driving pressure. The specific flux is
expressed in gallons per square foot per day per pounds per square inch (gfd/psi) at 25° C (77°F)
(See Operational Formulae, pages xi-xiv).
3.6.2.2 Net Driving Pressure
The pressures of the feed water and concentrate streams were recorded twice per day. The
average of feed and concentrate pressure readings minus the average osmotic pressure is the net
driving pressure of the system (See Operational Formulae, pages x-xiii).
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3.6.2.3 Percent Water Recovery
In order to calculate the percent water recovery of the treatment system, the permeate rate of the
membrane module is divided by the feed rate to the unit. Multiplying this result by 100 equals
the percent water recovery of the system (See Operational Formulae, pages xi-xiv).
3.7 Verification Task Procedures
The procedures for each task of verification testing were developed in accordance with the
requirements of the EPA/NSF ETV Protocol for Equipment Verification Testing for Removal of
Inorganic Constituents, Chapter 2 - and EPA/NSF ETV Protocol for Equipment Verification
Testing for Removal of Inorganic Constituents, Chapter 2 -Testing Plan for the Removal of
Inorganic Chemical Contaminants by the Reverse Osmosis or Nanofiltration (EPA/NSF, 2000).
The Verification Tasks were as follows:
Taskl: Membrane Operation
• Task 2: Cleaning Efficiency
Task 3: Finished Water Quality
Task 4: Data Handling Protocol
Detailed descriptions of each task are provided in the following sections.
3.7.1 Task 1: Membrane Operation
Membrane operational characteristics were identified in this task. The purpose of this evaluation
was to quantify operational characteristics of the membrane element module. Information
regarding this task was collected throughout the length of the 34-day verification study.
The objectives of this task were to:
1. Establish appropriate operational parameters
2. Demonstrate the product water recovery achieved
3. Monitor the rate of decline of specific flux over extended operation
4. Monitor raw water quality
Standard operating parameters were established through the use of the manufacturer's O&M
Manual and the initial operations of the Rosy-200 pilot test unit. After establishment of these
parameters, the unit was operated under those conditions. Operational data were collected
according to the schedule presented in Table 3-2.
3.7.1.1 Water Recovery
The range of water recoveries used in for the verification study was 13.1 to 15.4%. The
manufacturer selected this approximate range after examination of the initial operation data.
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3.7.1.2 Applied Pressure
Based on data generated during initial operations, the manufacturer selected a maximum applied
pressure to the membrane element module of 150 psig.
3.7.1.3 Prefilter Replacement Frequency
Good engineering practice dictates that the 5|i prefilter cartridges be changed when the pressure
drop across them exceeds 10 psi. During the early portion of the testing schedule, the 2-20" long
cartridges were replaced every other day; however, a high turbidity event in the tunnel during the
st
night of April 1 caused a plant shut-down (plant turbidimeter spiked at 11.83 NTU) and almost
completely plugged the prefilter cartridges, resulting in a drop in the membrane system pump
pressure to 50 psig. From April 2 until the end of the testing activity, the 5|i prefilter cartridges
were changed daily.
3.7.2 Task 2: Cleaning Efficiency
Cleaning efficiency procedures were identified in this task. The objectives of this task were to:
1. Evaluate the effectiveness of chemical cleaning for restoring permeate rate and rejection
characteristics of the membrane system.
2. Confirm that the manufacturer's cleaning recommendations are sufficient to restore
membrane productivity.
Good engineering practice requires that chemical cleaning of reverse osmosis spiral-wound
membrane elements be performed when the pressure drop (feed to concentrate) exceeds 10% or
when the percent solute rejection drops by more than 10%. Since neither of these conditions
occurred during the verification testing period, chemical cleaning was performed at the
conclusion of the 34-day period. The membrane element module was cleaned following the
manufacturer's recommendations on April 17, 2000.
There was a reduction in specific flux rate from 0.25 gfd/psi to 0.20 gfd/psi at the end of the
testing period. This drop was suspected to be caused by ferric hydroxide fouling; therefore, the
cleaning chemical used was a 50-gallon solution of citric acid dissolved in permeate at a
concentration of 2% by weight. The cleaning solution was pumped into the membrane housing
from a 50 gallon cleaning tank through a 5 micron filter cartridge. The flow rate though the
membrane module was 19 gpm at a feed pressure of 10 psig. The Model ROSY-200 pilot test
unit was equipped with three way valving to ensure that the permeate and concentrate streams
were redirected back to the cleaning tank for recirculation for one hour.
After recirculation of the cleaning solution through the KMS TFC®-ULP4 Reverse Osmosis
Membrane Element Module, the pump was turned off and the system allowed to soak for 1.75
hours. Then the membrane element module was rinsed with raw water for 30 minutes and placed
back on-line.
The citric acid cleaning solution was directed to the raw water wet well for dilution prior to
discharge to the Snyderville Sewer Improvement District.
30
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At the conclusion of the cleaning and immediately after placing the system back on-line, the
following operational data were recorded:
• Flow rates
• System recovery
• Temperature
• Specific flux
The following analytical data were taken on the chemical cleaning solution after the membrane
module had been cleaned:
• pH
• Temperature
• Total iron
• TDS
Visual appearance of the cleaning solution was also noted. The recovery of specific flux was
calculated by measuring the ratio of the specific flux at the beginning of the test to the specific
flux just before cleaning the membrane. Photograph 5 illustrates the KMS cleaning (CIP)
system.
31
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Photograph 5 - CEP unit used for cleaning membrane element modules.
-------
3.7.3 Task 3: Finished Water Quality
Procedures for the collection and analysis of finished water quality samples are identified in this
task. The purpose of this task was to demonstrate whether the manufacturer's stated treatment
capabilities are attainable. The goal of this portion of the ETV test was to determine the
equipment's capability to consistently remove total arsenic from feed water.
Testing on finished water was conducted throughout the length of the 34-day run. Finished water
samples were collected and speciated daily for arsenic and antimony. Weekly collection and
analysis of finished water samples was performed for TDS (2), fluoride, iron, manganese and
sulfate. Monthly samples were collected for analyses of alkalinity, LSI, turbidity, TSS, silica and
TOC.
Sample collection and analysis was performed according to procedures adapted from Standard
Methods for the Examination of Water and Wastewater, 20th edition, (APHA, et. al., 1998).
3.7.4: Task 4: Data Handling Protocol
Water quality data were collected at the specified intervals during the testing period. The
monitoring frequency for the water quality parameters is provided previously in Table 3-1. This
table identifies those parameters that were obtained on-site as well as those which were collected
and analyzed at the State Laboratory.
Arsenic samples were taken daily on the feed, concentrate and permeate streams. The samples
were then speciated into the insoluble form, As (III) and As (V) on-site prior to submission to the
laboratory for analysis.
The conductivity of feedwater, permeate and concentrate streams was used to calculate the
osmotic pressure gradient across the membrane on a daily basis, and then converted to TDS
equivalent. Osmotic pressure gradient values were used for calculation of net driving pressure
and specific flux on a daily basis. Mass balances for specified water quality parameters were also
calculated at a minimum of once weekly.
On-site data were manually entered into the On-site Logbook containing preprinted spreadsheets
for date, time and each required parameter. As laboratory data were received, they were
manually entered into the same logbook. Computer spreadsheets containing these identical data
were prepared with Microsoft ® Excel Software and brought up-to-date on a daily basis.
A laboratory research notebook (with carbon copy) was also maintained on-site. Daily notes on
operating details, such as times for each activity (filter cartridge replacement, operating data
measurements, analytical sample collection, etc) as well as all observations relating to the testing,
were entered into this notebook.
Chain-of-custody forms were obtained from the State Laboratory and filled out with the
appropriate COA analytical sample identification. These forms accompanied each sample to the
laboratory where computer-generated State Laboratory identification codes were assigned to each
sample. Copies of the original chain-of-custody forms with the state-assigned codes were
33
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returned to COA for reference to the final analytical results submitted on computer-generated
forms (Appendix D). A total of just fewer than 1000 analyses were reported on arsenic alone
using this procedure.
3.8 QA/QC Procedures
Establishment and implementation of strict quality assurance and quality control (QA/QC)
procedures is important, in that if a question arises when analyzing or interpreting data collected
for a given experiment, it will be possible to verify exact conditions at the time of testing. The
following QA/QC procedures were utilized during the verification testing.
3.8.1 Instruments with Daily QA/QC Verification Procedures
Daily QA/QC procedures were performed on the bench pH meter and hand-held conductivity
monitor.
3.8.1.1 pH Meter
Analyses were made by SM 4500-H+ A three-point calibration (pH 4, 7 and 10) with NIST
traceable pH buffers was performed daily. Between tests, the pH probe was kept wet in KCI
solution. For on-site determination of pH, field procedures were used to limit absorbance of
carbon dioxide to avoid skewing results by poorly buffered water.
pH measurements do not lend themselves to "blank" analyses. Duplicates were run once a day.
Performance evaluation samples were analyzed during the testing period. Results of the
duplicates and performance evaluation were recorded. The unit was also calibrated against a
standardized pH instrument in the State of Utah Laboratory and found to be within 5% accuracy.
3.8.1.2 Conductivity Monitor
The hand-held Myron L Ultrameter Model P (serial #6 EVAL) conductivity meter was sent to the
manufacturer for calibration prior to the start of verification testing. On a daily basis, the
monitor was also calibrated with standard solutions from the manufacturer.
3.8.2 In-1/me Thermometer
Temperature was measured in accordance with SM 2550 two times daily at the same time other
operational data were gathered. The thermometer read in 1.0°F increments, and was an NIST
Traceable thermometer mounted in the pipe between the high-pressure pump and the membrane
element module.
3.8.3 In-Line Pressure Gauges
Pressure gauges were originally mounted on the inlet and outlet of the 5|i prefilter cartridges as
well as on the feed and concentrate sides of the membrane element module. An evaluation of the
accuracy of these gauges revealed that they all were inadequate, so the gauges were removed and
replaced with quick-disconnect fittings to allow all pressure readings to be made with glycerin-
34
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filled NIST traceable gauges installed for each reading. The prefilter pressures were read with a
0-60 psig Ametek Model No. 1980L (Certificate # 0084-6); the membrane pressures were read
with a 0-200 psig Ametek Model 1980 L (Certificate # 0068-7), certificates of calibration are
located in Appendix F.
3.8.4 In-Line Flow Meters
The test unit was equipped with panel mounted acrylic flow meters to read permeate and
concentrate flow rates; however, the accuracy of these meters was determined to be too poor to
use, so the "bucket and stopwatch" flow rate procedure was utilized for those flow
measurements. The permeate and concentrate lines were equipped with three-way valves which
allowed the total flow to be diverted for these measurements.
3.8.5 Turbidity Meters
Turbidity readings were required only once per month; however, bench turbidimeter readings
were taken at the beginning and end of the testing. The benchtop turbidimeter (Hach 21 OOP) was
calibrated at the start of testing and then weekly, during the testing period, against primary
standards. Manufacturer's procedures for maintenance were followed and the schedules for
maintenance and cleaning noted in the logbook. All glassware was dedicated and cleaned with
lint free tissues to prevent scouring or deposits on the cells. Secondary standards (0.0, 0.4 and
20.0 NTU) were used to calibrate the turbidimeter with each use. Standard Methods 2130 was
employed for measurement of turbidity.
3.8.6 Tubing and Fittings
The tubing and fittings associated with the Rosy-200 pilot test unit were inspected to verify that
they were clean and did not have any holes or cracks in them. Also, the tubing was inspected for
brittleness or any condition, which could cause a failure.
3.8.7 Off-Site Analysis of Chemical Samples
3.8.7.1 Organic Parameters (Total Organic Carbon)
COA collected samples for this parameter in glass bottles supplied by the State of Utah
Laboratory and delivered the samples to the laboratory. Samples were preserved, held and
shipped in accordance with SM 5010B and SM1060.
3.8.7.2 Inorganic Samples
Inorganic samples were collected, held in the refrigerator at 4°C and shipped in accordance with
SM 3010B and C and 1060 and EPA §136.3, 40 CFR Chapter 1, every week. Proper bottles and
preservatives, where required (iron and manganese for example), were used. Although the travel
time was brief, samples were shipped in coolers at 4°C.
35
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3.8.8 SDI Measurements
SDI (Silt Density Index) measurements of the feedwater stream were required to be made once
per month. The initial reading was taken with a manual SDI unit (Osmonics, Inc.) on March 15,
2000 and another reading with both the manual unit and an Auto SDI unit (Osmonics, Inc.) on
April 17, 2000.
The test involves measuring the rate of decay of water flow through a 0.45|i filter disc under a
constant pressure (30 psi) for a specified length of time. The test was developed under the
auspices of the ASTM Committee on Water and assigned a test number ASTM D 4189-95.
The equipment used for the manual SDI measurements was an Osmonics, Inc. SDI Kit, serial No.
00-1113664-34. It requires connecting the water supply and using a stopwatch to collect the time
data. On April 17, an Osmonics Auto SDI unit was used to check the manual equipment. These
measurements were made downstream of the 5|i prefilter cartridges.
36
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Chapter 4
Results and Discussion
4.1 Introduction
The verification testing of the Koch membrane module, which occurred at the Park City Spiro
Tunnel Water Filtration Plant, commenced on March 15, 2000, and concluded on April 17, 2000.
Chemical cleaning was performed on April 17, 2000.
This section of the verification report presents the results of the initial operations period as well
as the verification testing period and a discussion of the results. Results and discussions of the
following are included: initial operations, membrane operation, cleaning efficiency, finished
water quality and QA/QC.
4.2 Initial Operations Results
An initial operations period allowed COA to refine the unit's operating procedures and to make
operational adjustments as needed to successfully treat the source water. The primary goals of
the initial operations period were to establish an optimum water recovery and operating pressure
for the test.
A characteristic of many reverse osmosis membrane elements is that after startup (the first 24 to
48 hours), the flux rate is unusually high. This initial period is known as "flux stabilization" and
this flux rate does not reflect the normal operating flux of the element. For this test, the initial
specific flux was 0.27 gfd/psi and dropped to 0.25 gfd/psi on days two and three. The specific
flux then stabilized in the 0.23-0.24 gfd/psi range for several days. This change represented a
drop of 10-15% in specific flux. The permeate rate during the first three days of operation
dropped from a high of 1.22 gpm to 1.10 gpm after three days, which is a 10% reduction in
permeate flow.
4.2.1 Water Recovery
Based on the data collected during the initial operations period, the manufacturer determined that
the treatment unit would be capable of operating at a water recovery rate [(permeate
flow/feedwater flow)* 100] of 15% at the feedwater temperature of 49°F (9.44°C). The actual
recovery data calculated from twice-daily flow readings ranged from 13.1% to 15.4% over the
duration of the test. The individual flow measurements are presented in Appendix G, as recorded
in the On-Site Logbook.
4.2.2 Operating Pressure
As defined in the Operational Formulae section of this report, the net driving pressure is the
average pressure across the membrane minus osmotic pressure and any backpressure. The
osmotic pressure calculated from TDS data was less than 10 psi and there was no backpressure
on the system. At the specified flow rate, the pressure drop from the feed end to the concentrate
end of the module was within specifications and ranged from 3 to 10 psig over the duration of the
37
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test. In consultation with the manufacturer, COA determined that the optimum operating
pressure for this test was to be 150 psig. The Net Driving Pressure (NDP) varied from 132.4 to
143.6 psi during the testing period.
4.3 Verification Testing Results and Discussion
The results and discussions of membrane operation, cleaning efficiency, finished water quality
and data handling are presented below.
4.3.1 Task 1: Membrane Operation
The purpose of this evaluation was to quantify operational characteristics of the membrane
element module. Information regarding this task was collected throughout the length of the
verification study.
Standard operating conditions were established through the use of the manufacturer's O&M
Manual and during the Initial Operations period of the verification testing. Operational data were
collected according to the schedule presented in Table 3-2.
Osmotic Pressure Gradient
As defined in the Operational Formulae section of this report, the osmotic pressure gradient is
normally determined based on the Total Dissolved Solids (TDS) concentrations measured in the
feedwater, the concentrate, and the permeate. The osmotic pressure gradient is then used as part
of the calculation for determining Net Driving Pressure (NDP). The permeate flow and the NDP
are then used to calculate the Specific Flux for the module.
The Test Plan stated that TDS measurements be made by the State Laboratory once per week (in
actuality, COA submitted samples twice per week). While twice-weekly TDS data provided a
good data set for tracking the TDS levels and the unit performance in treating TDS, it would be
preferable to have daily calculations for NDP and Specific Flux. Conductivity, which was
monitored in the field on a twice-daily basis, can be used as a surrogate to estimate the TDS
concentration.
Conductivity is significantly affected by the characteristics of the specific solute, such as valance,
as well as the total concentration. Therefore, conductivity cannot provide an exact determination
of TDS concentration. However, given sufficient data on a specific water source, a correlation
can be developed between conductivity and TDS that can be used to provide a very good
estimate of the TDS concentrations. Conductivity meter manufacturers and other companies
involved in the water purification industry have also developed conversion charts and graphs
based on a "typical" mix of solute chemistries in water that provide the basis for determining
TDS levels from conductivity measurements. Both methods of estimating TDS concentrations
can be used, but direct correlation factors developed for a specific water source are generally
more accurate than using values based on "typical" water. For this verification test there are
eleven sets of TDS data and corresponding conductivity measurements. It was determined that a
conversion factor could be developed from these data and the conversion factor could be used to
convert conductivity data to TDS concentration.
38
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The conductivity readings, taken closest to the eleven TDS collection times, were divided into
the TDS concentrations. These results for the feed and concentrate streams were then averaged to
generate a pooled average figure that was then used as a multiplier to convert osmotic pressure
calculations to the TDS basis. Table 4-1 provides a summary of TDS data in the feed,
concentrate and permeate streams. The TDS and conductivity data used to determine the
conversion factor are shown in Table 4-2. As can be seen in Table 4-3, the correlation between
TDS and conductivity did vary somewhat over the data set, but the standard deviation and
confidence interval statistics show that the variation was generally quite small. Therefore, the use
of the conversion factor of 0.733 (mg/l)/(|iS/cm) was considered to provide a very good estimate
of the feedwater and concentrate TDS concentration.
TDS
An important parameter of reverse osmosis membrane performance is TDS rejection, which is
the ability of the module to reduce total dissolved solids concentration in a feedwater stream.
TDS measurements (by evaporation) were made by the State Laboratory on approximately a
twice per week basis (11 measurements in 5 weeks). Table 4-1 provides a summary of TDS data
in the feed, concentrate and permeate streams as well as percent rejection. It should be noted that
over half of the permeate data are below the MDL (10 mg/L). Therefore, it was not possible to
calculate meaningful statistics for the permeate TDS results. The raw data used for this summary
are in Table 4-2. As expected, the Membrane Element Module removed 98% or better of TDS
from the feedwater stream.
Table 4-1: Total Dissolved Solids Summary
Feed
Concentrate
Permeate
Rejection
(mg/L)
(mg/L)
(mg/L)
%
Average
543
641
11
98
Minimum
438
518
<10
97
Maximum
572
668
18
98
Standard Deviation
40.6
42.6
2.6
0.50
Confidence Interval
(518, 568)
(616. 666)
(10. 13)
(98,98)
(1) All calculations use the MDL value (10 mg/L) as the permeate value for all data reported below the MDL.
Conductivity
To provide an indication of TDS concentrations in the feed, concentrate and permeate streams on
a daily basis, conductivity measurements were taken with a Myron L Model 6P Ultrameter. For a
given solute (or mix thereof), as stated earlier, conductivity can be related to TDS, and the ratio
of TDS to Conductivity should be approximately a constant. Table 4-2 compares the
conductivity measurements with TDS data and lists the ratio of TDS to Conductivity. Table 4-3
summarizes this data. The variations in the ratios may be attributed to the fact that the
conductivity reading and TDS sample collection activities were sometimes separated by several
hours. During that time interval, variation in the solute mix in the feedwater may have occurred.
39
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The variation in the ratios is quite small as shown by the standard deviation and confidence
intervals. Because over half of the permeate TDS data are below the MDL of 10 mg/L, the ratio
(TDS/Conductivity) calculation for this stream is not meaningful. The pooled average conversion
ratio (0.733 (mg/1 )/(|iS/cm)) from the feedwater and concentrate data was used in the calculation
for determining Specific Flux on a TDS basis (discussed below).
Table 4-2: Total Dissolved Solids, Conductivity and TDS/Conductivity Ratio vs. Time
Feed Concentrate Permeate
TDS
Conductivity
TDS/
TDS
Conductivity
TDS/
TDS
Conductivity
(mg/L)
(|iS/cm)
Cond.
(mg/L)
(|iS/cm)
Cond.
(mg/L)
(|iS/cm)
(mg/L)/
(mg/L)/
Date
(|iS/cm)
(|iS/cm)
3/17/00
554
765.3
0.724
646
881.4
0.733
10
8.45
3/20/00
566
781.9
0.724
638
882.6
0.723
<10
12.32
3/23/00
-
768.2
NA
666
892.9
0.746
14
10.78
3/27/00
438
780.8
0.561
668
902.2
0.740
12
9.62
3/29/00
554
712.6
0.777
658
821.2
0.801
<10
11.82
4/4/00
564
752.2
0.750
656
857.8
0.765
<10
13.98
4/5/00
572
749.8
0.763
518
858.2
0.604
<10
12.01
4/10/00
558
710.2
0.786
628
841.7
0.746
<10
11.91
4/13/00
566
750.6
0.754
658
863.6
0.762
18
12.89
4/17/00
512
744.3
0.688
646
847.4
0.762
<10
12.36
4/17/00
548
747.2
0.733
666
880.0
0.756
10
6.47
- No Data Reported
Table 4-3: TDS to Conductivity Ratio Summary
Feed
(mg/L)/(^S/cm)
Concentrate
(mg/L)/( [iS/cm)
Average
0.726
0.740
Minimum
0.561
0.604
Maximum
0.786
0.801
Standard Deviation
0.0647
0.0496
Confidence Interval
(0.686,0.766)
(0.711,0.769)
Pooled average
Feed + Concentrate
= 0.733 ((mg/l)/(|iS/cm))
Specific Flux
Specific Flux is the permeate flux at a constant temperature divided by the Net Driving Pressure,
which is the average pressure of the feed and concentrate minus any osmotic pressure and
permeate back pressure. In this test, the stream was discharged to atmosphere, so the permeate
back pressure was zero. Osmotic pressure data were calculated from conductivity data by
40
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averaging the feed and concentrate conductivities, subtracting the permeate conductivity and
dividing that figure by 100. These results were then multiplied by the conductivity to TDS
conversion factor of 0.733 (mg/1 )/(|iS/cm)). Thus, all of the NDP results and the Specific Flux
results calculated using the daily NDP values are based on TDS concentrations.
As discussed in Section 3.6.2.1, flux, which is a method of expressing permeate flow, is
customarily normalized to 25°C (77°F) using the formula shown in Section 3.6.2.1. Normalizing
the flux to a constant temperature helps to account for the effect that the increased viscosity of
water at lower temperatures has on permeate flow through a membrane. The feedwater
temperature measured a steady 49°F (9.4°C) during the testing period. All of the flux data,
calculated from measured permeate flow and membrane surface area, were corrected to 25°C
(77°F). The temperature corrected flux values were then used to calculate specific flux (permeate
flux/NDP). All of the specific flux results presented in the tables and figures below are based on
temperature corrected results and are on a TDS basis.
Table 4-4 lists the daily specific flux data. Table 4-5 summarizes these data and Figure 4-1
illustrates the decrease in the specific flux average during the 34-day test period. Two specific
flux data values were calculated each day. For Figure 4-1, the data points for each day were
averaged in order to generate the curve. The raw data from which specific flux values were
calculated are in Appendix G, along with a summary of calculation data.
Specific Flux = Permeate Flux
NDP
(Defined in Operational Formulae, pages x to xiii)
The KMS TFC®-ULP4 Reverse Osmosis Membrane Element Module exhibited an overall drop
of 26% in specific flux (0.27 gfd/psi to 0.20 gfd/psi) over the 34 day test period. When the "Flux
Stabilization" period is taken into consideration, the drop is 20% in specific flux (0.25 gfd/psi to
0.20 gfd/psi). A drop in specific flux virtually always results from membrane fouling, in that the
passage of pure water though the membrane into the permeate stream is inhibited by the presence
of fouling materials on the membrane surface. Because the specific flux calculation accounts for
variations in temperature, pressure drop and osmotic pressure (dissolved solids concentration), a
change in specific flux singularly reflects a change in permeate rate. The chemical cleaning
restored the specific flux to 0.25 gfd/psi, virtually the same level that was achieved after the
initial stabilization period (0.24-0.25 gfd/psi).
41
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Table 4-4: Specific Flux Data vs. Time
Date
Specific Flux (gfd/psi)
Date
Specific Flux (gfd/psi)
AM
PM
AM
PM
3/16/00
0.27
0.27
4/1/00
0.22
0.23
3/17/00
0.25
0.25
4/2/00
0.23
0.23
3/18/00
0.25
0.25
4/3/00
0.22
0.23
3/19/00
0.24
0.24
4/4/00
0.22
0.22
3/20/00
0.23
0.24
4/5/00
0.21
0.22
3/21/00
0.23
0.23
4/6/00
0.21
0.21
3/22/00
0.23
0.23
4/7/00
0.21
0.21
3/23/00
0.23
0.23
4/8/00
0.22
0.21
3/24/00
0.24
0.24
4/9/00
0.21
0.21
3/25/00
0.23
0.23
4/10/00
0.21
0.22
3/26/00
0.24
0.24
4/11/00
0.22
0.22
3/27/00
0.24
0.24
4/12/00
0.21
0.21
3/28/00
0.24
0.24
4/13/00
0.21
0.21
3/29/00
0.23
0.23
4/14/00
0.21
0.21
3/30/00
0.23
0.23
4/15/00
0.21
0.21
3/31/00
0.23
0.23
4/16/00
0.20
0.21
4/17/00
0.21
-
After
4/17/00
-
0.25
Cleaning:
Table 4-5: Specific Flux Data Summary of AM and PM Data (gfd/psi)
Average 0.23
Minimum 0.20
Maximum 0.27
Standard Deviation 0.015
95% Confidence Interval (0.22,0.23)
42
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0.280
5
w
H
_3
E
w
E
*s
e.
(Z3
0.260
0.240
0.220
0.200
0.180
0.160
0.140
0.120
0.100
/ / ^ / / / / ^ ^ ^ ^ ^ ^ ^ ^
Verification Test Date
Figure 4-1: Variation of Average Specific Flux Data vs. Time
SDI
Silt Density Index (SDI) is a measurement of the quantity of suspended solids in a water supply
that could potentially foul reverse osmosis membrane elements.
To date, SDI is considered the most reliable "field" measurement technique for predicting the
fouling propensity of feedwater supplies to a reverse osmosis membrane; however, it does have
several limitations, as follows:
1) The test operates in the "dead-end" or "once-through" mode, in that the entire water
flow passes through the filter disc as opposed to the "crossflow" design of reverse
osmosis, more fully described in Chapter 2.
2) The pore size of the filter disc is 0.45|i, whereas the pore size of the reverse osmosis
membrane is less than 0.002|i, meaning that extremely small sized colloidal material
that may foul the reverse osmosis membrane would not show up in the test.
3) Because the reverse osmosis process concentrates all salts, it is possible that the
solubility limits of some sparingly soluble compounds may be exceeded, resulting in
fouling from sources, which cannot be measured in the SDI Test.
Table 4-6 lists all of the SDI data, which are plotted in Figure 4-2.
43
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Table 4-6: Feedwater SDI Measurements
Date Time SDI Reading
3/15/00 1810 2.5
3/16/00 1600 6.64
3/17/00 0921 2.1
3/18/00 1615 5.8
3/19/00 0818 6.3
3/19/00 1448 7.8
4/17/00 1130 2.7
9 -|
8 -
7 -
6 -
5 -
4 -
3 -
2 -
1 -
0 -
1810 1600 0921 1615 0818 1448 1130
3/1 5/00 3/16/00 3/1 7/00 3/1 8/00 3/1 9/00 3/1 9/00 4/1 7/00
Verification Date and Time
Figure 4-2: Feedwater SDI Measurements vs. Time
The physical appearance of the filter discs does not always correlate with the SDI reading.
Photocopies of the several of the discs are presented in Appendix H.
Turbidity
Another parameter that measures insoluble particulate material in water supplies is turbidity.
There is a paucity of data relating turbidity to membrane fouling; therefore, SDI is the preferred
parameter used in this test. As stated above, SDI is considered a better predictor of membrane
fouling than turbidity; however, turbidity is a more common measurement technique used in
virtually all water treatment plants. Turbidimeters are used widely in the water industry to
monitor changes in water quality due to particulate loading changes in the water supply. The
meters are either bench top units, which are easy to use so that frequent measurements are made
or they are continuous recording units, capable of providing instantaneous readings twenty-four
hours a day. Turbidity readings were recorded from the Treatment Plant wall mounted in-line
44
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turbidimeter almost every day, as well as from benchtop turbidimeter measurement records.
Both instruments read the raw water and the sampling points were within 50 feet of each other.
Table 4-7 lists the two sets of readings over the testing period.
Some discrepancies between the in-line and bench-top turbidimeters were noted. Several
explanations for these are offered, as follows:
1. Difference in the analytical techniques between the in-line and bench-top turbidimeters:
The bench-top turbidimeter uses a glass cuvette to hold the sample; this cuvette can
present some optical difficulties for this instrument. The in-line turbidimeter has no
cuvette to present a possible interference with the optics of the instrument. The low level
of turbidity can create analytical difficulties, particularly for the bench-top instrument.
Manufacturer's specifications state that stray light interference is less than 0.02 NTU.
Stray light interference at the low turbidity levels tested could account for the differences
in the readings.
2. Normal geologic activity such as portions of the Spiro Tunnel walls and ceiling falling
into the water caused short-term turbidity spikes in the feedwater that may have affected
the accuracy of the in-line plant turbidimeter between routine cleanings. For example, a
turbidity spike occurred at 0300 on April 2, 2000, which shut down the filtration plant
(the turbidity alarm level was set at 5.0 NTU). The turbidimeter was cleaned and
returned to service.
3. Although attempts were made to collect bench-top turbidity samples at the same time that
in-line turbidimeter readings were made, the logistics of the sampling locations resulting
in small time differences may have resulted in slight changes in water quality between
these events.
Because the Spiro Tunnel Bulkhead water upstream of the bulkhead is mainly flowing along the
bottom of an open passageway, it is susceptible to disturbances from falling rock and other
normal geologic activity. As a result, the level of suspended solids in the feedwater could change
drastically during short periods, as evidenced by turbidity spikes recorded by the Spiro Water
Filtration Plant turbidimeter from a baseline reading of less than 1 NTU up to a maximum of
almost 12 NTU. While these fluctuations can cause short-term treatment difficulties and could
cause membrane fouling, there was no evidence that the fluctuations impacted the membrane unit
during the test period.
The 0.45|i filter discs used in the speciation of arsenic samples to collect the "bottle B" analyte
provide further evidence that wide fluctuations in suspended solids concentrations can occur in
this feedwater. Most of the filter discs were dried and retained. The difference in shades and
intensity of the reddish-brown color (presumed to be ferric hydroxide) is very evident in these
and photocopies are provided in Appendix H. The varying intensity and shades indicate that
particulate present in this water varies not only in concentration but also in chemical
characteristics. In spite of these variations, the membrane unit continued to function well and
there was no noticeable catastrophic fouling of the membrane. Permeate flow was steady and
specific flux remained virtually constant.
45
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Table 4-7: Turbidity Readings (N IT ) vs. Time
Raw Water (NTU)
Date
Treatment Plant
In-Line
Bench
3/15/00
0.78
0.97
3/16/00
1.00
1.0
3/17/00
0.91
0.90
3/18/00
0.90
0.94
3/19/00
1.17,2.35, 3.65, 11.79
1.10,2.41,-, 11.3
3/20/00
-
1.23
3/21/00
0.72
0.72
3/22/00
0.78,0.93,0.82
-
3/23/00
1.02
-
3/24/00
1.33, 1.26
1.92, 1.83
3/25/00
1.20
1.91
3/26/00
2.43
0.89
3/27/00
0.98,0.99
1.44. 1.17
3/28/00
0.96, 0.90
1.22, 1.16
3/29/00
0.97, 0.87
1.37, 1.41
3/30/00
1.11
0.94
3/31/00
1.17
0.97
4/1/00
-
-
4/2/00
*11.83, 1.7
1.9
4/3/00
0.98
1.31
4/4/00
-
-
4/5/00
1.5
1.90
4/6/00
1.4
1.87
4/7/00
1.2
1.4
4/8/00
-
-
4/9/00
1.58
1.96
4/10/00
1.60
1.98
4/11/00
-
-
4/12/00
1.7
2.1
4/13/00
1.80
1.76
4/14/00
1.9
1.4
4/15/00
1.9
1.5
4/16/00
1.36
1.84
4/17/00
-
0.32
At 12:30am a high turbidity alarm sounded, reading was 11.83
- No Data Reported
4.3.2 Task 2: Cleaning Efficiency
The Koch membrane module was chemically cleaned utilizing a commercially available CIP unit
containing 50 gallons of a 2% (wt/wt) citric acid solution. The cleaning took place in the
afternoon of April 17, 2000, following the termination of the verification testing that morning.
After a one-hour recirculation of cleaning solution through the membrane module and a 1 -3/t hour
soak, it was rinsed with feed water for approximately V2 hour and placed back on line to
46
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determine the effectiveness of the cleaning. Table 4-8 summarizes the cleaning process data.
Unfortunately, due to a communication error, samples for TOC analysis were collected from the
cleaning solution in containers without the necessary preservative.
Table 4-8: Membrane Element System Cleaning Data
Item
Description
Composition of Cleaning Chemical
Citric Acid
8
,5Lb/50gal Permeate
Quantity of Cleaning Chemical (~2% wt/wt Solution)
Feed Flow Rate
19.3 gpm
System Recovery
16.6%
Total Chemical Cleaning Time
3.25 hours
Soak Time
1.75 hours
Recirculation Time
1.0 hours
Rinse Flow Rate
6.6 gpm
Rinse Time
30 minutes
Cleaning Temperature (Initial)
14.6°C
Cleaning Temperature (Final)
16.6°C
Snyderville Sewer Improvement
Disposal Method of Cleaning Water
District
Specific Flux (Initial)1
0.21 gfd/psi
Specific Flux (Final)2
0.25 gfd/psi
Recovery of Specific Flux3
100%
(1) Specific Flux Initial is the reading before cleaning.
(2) Specific Flux Final is the reading after cleaning.
(3) Recovery of Specific Flux is the comparison between the after cleaning reading
and the value obtained at the beginning of the test (new membrane) after the
stabilization period ended on 3/17/00. See Section 4.2
Chemical Analysis of Cleaning Solution
pH
2.61
Temperature (°C)
16.6
TDS (mg/L)
4026
Total Iron (mg/L)
466.0
47
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At the completion of the cleaning regimen, the membrane module was placed back on line to
determine the effect of the cleaning on the module performance. Table 4-9 contains the operating
data from this retest, and Table 4-10 lists several performance parameters.
Table 4-9: Operating Data after Cleaning
Parameter
Measurement
1. Permeate Flow Rate (gpm)
1.10
2. Concentrate Flow Rate (gpm)
5.50
3. Feed Flow Rate (l+2)(gpm)
6.60
4. Element Inlet Pressure (psi)
150
5. Element Outlet Pressure (psi)
147
6. Element Recovery ((1/1+2) xlOO)
16.7%
7. Conductivity (Feed) (us/cm)
747.2
8. Conductivity (Permeate) (us/cm)
6.47
9. Conductivity (Concentrate) (us/cm)
880.8
10. Feed Temperature (°F)
49
11. Osmotic Pressure (Air)(psi)
5.94
12. Net Driving Pressure (psi)
142.6
13. Specific Flux (@25°C)(gfd/psi)
0.25
Table 4-10: Module Performance after Cleaning
Paramelcr Feed
Concentrate
Permeate
pH 7.32
7.37
5.87
TDS 548
666
10
Turbidity (NTU) 0.32
0.35
0.10
The cleaning process was considered successful, as the performance of the unit after cleaning
was very similar to the unit's performance early in the test when any build up of materials that
might foul the membrane could not affect the unit. While the unit did not require cleaning after
34 days of operation, the permeate flow had dropped from about 1.10 gpm (1.08-1.12 gpm for
Day 3-5) in the early part of the test to 0.93 gpm (lowest rate was 0.90 gpm the previous day) on
the last day. This represent a decrease of approximately 15% in flow rate for the permeate. The
specific flux also decreased from approximately 0.23 gfd/psi to 0.25 gfd/psi in the first week to
0.20 gfd/psi after 34 days. The steady decline in permeate flow and specific flux indicated that
the unit would need cleaning in the near future. The cleaning process demonstrated that the
procedure outlined for cleaning this unit did perform properly and no damage or deterioration to
the membrane unit occurred because of the cleaning process. The permeate flow rate returned to
1.10 gpm and the specific flux returned to 0.25 gpd/psi after the completion of the cleaning cycle.
The operating conditions after cleaning were virtually identical to the conditions achieved with a
new membrane after the initial stabilization period.
48
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4.3.3 Task 3: Finished Water Quality
Water Quality Data Presentation
This section presents the membrane module rejection/removal characteristics for various arsenic
species and for antimony. The daily results for arsenic and antimony are presented in tabular and
graphical format along with summarized versions of the data. Other parameters, such as TDS,
conductivity, pH, fluoride, iron, manganese, sulfate, which provide general information on water
quality and can have an impact on membrane module performance, are presented in a
summarized format. All of the raw water quality data collected during the test period are
provided in Appendix D. The possible effects of iron fouling are also discussed in this section,
including a mass balance calculation. Feedwater temperature data were taken from the calibrated
in-line thermometer twice a day, and the temperature remained unchanged (49°F; 9.4°C)
throughout the test.
Overview of Arsenic Removal
The primary goal of this performance verification study was to evaluate the ability of the KMS
TFC®-ULP4 Reverse Osmosis Membrane Element Module to remove arsenic from the Park City
Spiro Tunnel Bulkhead water supply. The industry standard approach for evaluating a reverse
osmosis system's capability to remove a specific contaminant is to calculate the percent rejection
characteristics of the membrane module. The percent rejection characteristic is a measure of the
ability of the membrane module to remove or reject a particular contaminant, as defined under
the term "Percent Solute Rejection" in the Operational Formulae section, pages x-xiii. The
rejection percentage is calculated in the same manner as percent removal of a particular
constituent. The Tables and Figures presented in the following subsections illustrate the removal
characteristic of various species of arsenic by the KMS membrane module operating on this
feedwater source.
The results clearly show that the KMS membrane module, operating under the defined conditions
in this test, consistently reduced the total arsenic concentration in the permeate to 1.0 |ig/l or less.
Only one permeate result showed a high arsenic level (58.6 |ig/l), which is believed to be an
erroneous result because of mislabeled sample bottle. The average total arsenic in the feedwater
for the test period was 60 |ig/l and the average permeate concentration was 0.9 |ig/l. These data
show that over 98% removal of the total arsenic was achieved using the KMS module.
While the primary goal of the verification test was to determine the total arsenic
rejection/removal, the verification test also emphasized the collection of data for dissolved
arsenic, arsenic (in) and arsenic (V) present in the feed water. RO membrane technology is
normally utilized to remove contaminants that are dissolved in water as opposed to being used as
a filtration device for particulate material. While RO membranes can effectively remove
particulate from a water stream, particulate matter is actually a potential problem to membrane
systems of this type. The particulate can foul the membrane, which will cause frequent cleaning
cycles and high maintenance cost. The removal of particulate contaminants is generally better
achieved using other filtration technology. In fact, it is typically recommended that a filter of
some type be placed in front of the RO membrane system to remove particulates prior to
49
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treatment by the membrane module. In the test system a 5 |i cartridge filter was used ahead of the
membrane module. The cartridge filter was changed every two days at the beginning of the test
and daily beginning on April 2 for the remaining 16 days of the 34-day test period.
All of the samples for feedwater chemical analyses, except for turbidity, were collected after the
cartridge filters. The cartridge filters may have removed some portion of the insoluble arsenic
present in the water during periods of high turbidity. Elevated turbidity was measured on two
occasions and one of the events partially plugged the cartridge filters. However, the actual
amount of arsenic that may have been removed by the prefilter appears to be small to negligible.
The feedwater total arsenic measured during the verification period averaged 60 |ig/L, while the
average total arsenic in the raw water measured over the period 1980-1999 was 66 |ig/L. Also, on
one occasion (March 20), turbidity was monitored before and after the prefilter, with the raw
water showing a turbidity of 1.00 to 1.23 NTU and the feedwater after the prefilter was measured
as 1.44 NTU. While data was not routinely collected before and after the prefilter, this
information would indicate that the prefilter only removed material during high-level spikes of
suspended solids. The prefilter was sized to remove material greater than 5 micron in size. On
typical operating days the prefilter would not appear to have had a significant impact on the
feedwater water quality concentrations.
In order to provide additional information and more specific information on the capability of the
KMS unit to remove soluble arsenic species, dissolved arsenic and the two predominate valence
states of arsenic (in and V) were monitored throughout the test period. The results for dissolved
arsenic show that the average feedwater concentration was 42 |ig/l and the average permeate
concentration was 1.3 |ig/l. These results show indicate that the dissolved arsenic was actually
slightly higher than the total arsenic. The data for dissolved arsenic in the permeate may be
biased slightly high due to interferences from the sample preservation procedure. This could
cause an understatement of the actual percent rejection. In order to monitor for the various
arsenic species, sulfuric acid is used to preserve the samples. The use of the sulfuric acid is
suspected to have interfered with the accuracy of the dissolved arsenic results at low
concentration levels in the permeate. This issue is discussed further in the subsection presenting
the dissolved arsenic results and in detail in Appendix I. In any case, the dissolved arsenic
concentration in the permeate was equal to or less than 1.5 |ig/l, which is well below the current
and proposed arsenic MCL (current -50 |ig/l; proposed- 10 |ig/l).
NSF performed a quality control review of the arsenic analyses. The report suggested that a
higher quantitation limit might be more appropriate for these results. The QC review stated that
the quantitation limit of 0.5 |ig/l used by the laboratory may be too low and recommended a
quantitation limit of 3-5 |ig/l, which would eliminate the discrepancy between the total and
dissolved arsenic data. Reporting the data at a higher quantitation limit would impact the
rejection percentage calculation, lowering the calculated percent rejection. Additional
information on the QA report is discussed in the QA section 4.5.10.
All of the data are presented exactly as reported by the State of Utah laboratory. The laboratory
has indicated that the precision and accuracy of their test methods support reporting two or three
significant figures for the analytical data. They also concur that it is inappropriate to report data
as quantitative down to the minimum detection limit for arsenic measurement by ICP-MS, which
50
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is in the range of 0.1 to 0.2 |ig/l. Results below 0.5 |ig/l are considered only qualitative and not
quantitative. All arsenic data are reported to a detection limit (MDL) of 0.5 |ig/l, as reported by
the laboratory. Results below this limit are reported as <0.5 |ig/l. All of the above issues are
detailed in Appendix I.
Total Arsenic
Tables 4-11 and 4-12, and the Figure 4-3 present the daily and summarized results for total
arsenic analysis on the feed water, the concentrate and the permeate for the entire test period. The
percent rejection is calculated using the standard operational formula, which is equivalent to
calculating the percent removal of the contaminant. The feedwater total arsenic concentrations,
measured during the test period, were very similar to the levels recorded historically (Table 1-1).
Total arsenic concentrations ranged from 48.8 to 77 |ig/l with an average value of 60 |ig/l. The
total arsenic levels were mostly grouped within a narrow range as shown by the 95% confidence
interval of 58 to 63 |ig/l. Permeate concentrations were also very consistent with all but one value
being in the range of 0.7-1.0 |ig/l. The data indicate that the KMS unit was able to produce a
consistently high quality permeate stream within the range of feedwater concentrations
encountered during the test period.
One permeate result on April 12 was reported at 58.6 |ig/l, which was similar to the feedwater
and concentrate levels on that day. It is believed that the sample container was mislabeled for this
sample or an incorrect sample was collected. The results for this one day were not used in
developing the summary statistics reported in Table 4-12.
Inspection of the total arsenic data for the concentrate shows that there is a slight imbalance with
the total arsenic results. The expected process with reverse osmosis membrane technology is that
the membrane rejects the solute, while clean water passes through as permeate. This process
results in the solute being concentrated in the concentrate stream. Given the high degree of
rejection of arsenic by the unit, it would be expected that the concentrate stream would have a
higher concentration of arsenic than the feed water stream by about 17-18%. This is based on a
water recovery rate of 15% and very low arsenic in the permeate. The results show that the
concentrate stream averaged 64 |ig/l, while the feedwater averaged 60 |ig/l. The concentrate is
higher in concentration, but based on the water recovery rate and the permeate concentration, it
would be predicted to be closer to 70 |ig/l. These results may be within the accuracy and
precision of the laboratory to measure total arsenic and differentiate the levels in the two streams,
or may be because some of the arsenic in the particulate form is captured within the membrane.
There will be more discussion of this issue in the section that shows the mass balances for
arsenic and other constituents. The permeate results for total arsenic and the individual species
show that the membrane unit very effectively rejected or removed the arsenic from the feed
water.
51
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Table 4-11: Total Arsenic Readings
Total Arsenic
Date
Feed
Concentrate
Permeate
Rej ection/Removal
(l-ig/L)
(Mg/L)
(Mg/L)
(%)
3/15/00
75
78
0.78
99
3/16/00
66
72
0.79
99
3/17/00
71
77
0.74
99
3/18/00
74
79
0.8
99
3/19/00
77
78
0.8
99
3/20/00
65
71
1
98
3/21/00
59
64
1
98
3/22/00
57
60
0.92
98
3/23/00
61
66
1
98
3/24/00
63
78
0.97
98
3/25/00
62
64
0.89
99
3/26/00
55.9
59.8
0.8
99
3/27/00
67
67
0.78
99
3/28/00
55.6
60.1
0.9
98
3/29/00
66
66.8
0.8
99
3/30/00
55.4
60.2
0.8
99
3/31/00
60.3
66
0.8
99
4/1/00
62.6
67.2
0.9
99
4/2/00
49.8
48.1
0.8
98
4/3/00
48.8
45.1
0.8
98
4/4/00
56.9
58.4
1
98
4/5/00
56.6
57.6
0.9
98
4/6/00
67.5
87.9
0.9
99
4/7/00
56.8
65.7
1
98
4/8/00
61.7
84.9
0.9
99
4/9/00
61.5
61.4
0.9
99
4/10/00
58.3
55.4
0.9
98
4/11/00
50.2
53.3
0.7
99
4/12/00
55
59.4
58.62
NC
4/13/00
62
63.9
0.7
99
4/14/00
50
53.9
0.8
98
4/15/00
49.5
49.8
0.8
98
4/16/00
55.1
52.9
0.8
99
4/17/00
50.7
51.9
0.7
99
NC - Not calculated
(1) The reliability of the low-level data (MDL of 0.1 |ig/L to approximately 2|ig/L) should be considered as only
qualitative (not quantitative).
(2) Indicates likely mislabeled sample container for the permeate.
52
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Table 4-12: Total Arsenic Data Summary
Feed
Concentrate
Permeate1
Rejection
(Ug/L)
(US/L)
(Ug/L)
%
Average
60
64
0.9
99
Minimum
48.8
45.1
0.7
98
Maximum
77
87.9
1
99
Standard Deviation
7.5
11
0.09
0.21
Confidence Interval
(58, 63)
(61,68)
(0.8, 0.9)
(99, 99)
(1) The permeate results for April 12 were not used in the summary calculations.
Verification Testing Dates
Figure 4-3: Total Arsenic Concentration vs. Time
Note: Data from likely mislabeled permeate container on April 12 are not included in this figure
Dissolved Arsenic
While the overall goal of the verification test was to test the capability of the KMS Module to
consistently remove total arsenic from a feedwater, another important test and possibly an even
more important test for reverse osmosis units, is to measure the capability to reject a contaminant
dissolved in feed water. Section 2.2 described the basic principles for various pressure membrane
technologies. Reverse osmosis technology is the cross flow filtration process that produces the
highest quality permeate of any of the membrane technologies. RO membranes will typically
have the smallest pore sizes and the lowest molecular weight cut-off ranges resulting in the
ability of the membrane to reject a large portion of the dissolved salts present in feed water.
While RO units will also reject or capture suspended solids or colloidal matter, other pressure
53
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technologies, such as microfiltration or ultrafiltration, can reject or remove particulate matter at
lower operating pressures and cost. In fact if the contaminants to be removed are primarily in
particulate form and the particulate levels are high in the feed water, RO units can be problematic
to operate due to fouling of the membranes. RO units are generally best suited for and give the
best performance for constituents that are in the dissolved salt form. It would be expected that the
overall best system performance would be achieved for this membrane technology for feed
waters containing a high percentage of dissolved arsenic.
The dissolved arsenic and other dissolved solids will also have an impact on the operating
conditions of an RO membrane module such as the KMS Module. As discussed in Section 2.3
the concentration of dissolved salts has a direct impact on the osmotic pressure of the system and
the potential for fouling due to soluble salts forming precipitates on the membrane surface or in
the membrane pores. The data obtained before this test started and collected during the test
period show that the levels of dissolved arsenic and total dissolved solids are low enough that
even with a wide variation, the concentrations should have little impact on the actual pumping
pressures required to generate a reasonable permeate flow rate. The data collected for dissolved
arsenic during the test showed that the dissolved arsenic averaged 42 |ig/l and represented 70%
of the total arsenic present in the feed water.
Tables 4-13 and 4-14, and Figure 4-4 show the dissolved arsenic data for the feed water,
concentrate, and permeate collected during the test period. The feedwater concentration of
dissolved arsenic averaged 42 |ig/l. The permeate concentration averaged 1.3 |ig/l and the
variation in permeate concentration was in a very narrow range of 0.79 |ig/l to 1.5 |ig/l. The
KMS Module consistently rejected dissolved arsenic levels and produced a high quality
permeate. The average removal/rejection rate was 97%. There were anomalous data points for
the permeate on April 1 and April 12. On April first the concentrate results were very low at 1.5
|ig/l and the permeate was high at 50.5 |ig/l. It would appear that the sample bottles were
mislabeled or reversed. The permeate value of 42.9 |ig/l on April 12 appears similar to the
feedwater and concentrate for that day. It is most likely that the sample for this day were
inadvertently mislabeled. These data were not used in developing the summary statistics in Table
4-14.
A closer inspection of the dissolved arsenic data for the permeate show that there is an
inconsistency between the dissolved arsenic results and the total arsenic results (Tables 4-11 and
4-13). The total arsenic results are lower than the dissolved arsenic concentrations. This
obviously cannot be an accurate result. The feedwater and concentrate data show in all cases that
the total arsenic is higher than the dissolved arsenic. The concentration in these streams is much
higher suggesting that the problem only occurs at concentrations near the detection limit. These
data would suggest that the problem is related to interferences or contamination in the analysis at
very low concentrations.
Given this inconsistency, the State of Utah laboratory was asked to review the data and attempt
to explain the possible cause of the discrepancy. Their findings are presented in their entirety in
Appendix I. The basic cause of the problem, in their opinion, appears to be that the use of
sulfuric acid in the preservation process for the dissolved arsenic samples causes a positive
interference in the ICP-MS analysis. This positive interference is relatively small (a few tenths of
54
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a |ig/l; typically 0.4-0.6 |ig/l), but at the low concentrations being measured in the permeate, this
positive interference is significant. Therefore, the dissolved arsenic results appear to be biased
high. This positive bias results in an understating of the removal percentage and over stating of
the actual concentration for the dissolved arsenic in the feed water.
The NSF quality control review of the data suggested that a higher quantitation limit might be
more appropriate for the arsenic analysis. A higher reporting limit of 3 |ig/l would eliminate the
reporting discrepancy, but would result in potentially understating the overall performance of the
KMS Module. The NSF quality control review also hypothesized that the filter paper used to
filter the samples may be a source of arsenic. While all these factors can or should be taken into
account, the actual data as reported by the laboratory is reported here without adjustment.
Review of the dissolved arsenic results shown in Tables 4-13 and 4-14 shows that the KMS
Module performed well in rejecting dissolved arsenic in this feed water. The permeate results
show dissolved arsenic as less than 1.5 |ig/l and are probably less than 1.0 |ig/l based on the total
arsenic results. All of these levels are well below the current EPA MCL value of 50 |ig/l, the
proposed value of 10 |ig/l, and the WHO level of 10 |ig/l.
Table 4-13: Dissolved Arsenic Data
Date
Feed
Concentrate
Permeate
Rejection
Date
Feed
Concentrate
Permeate
Rejection
(Hg/L)
(Hg/L)
ftig/L)
%
(Ug/L)
(Ug/L)
(Ug/L)
%
3/15/00
52
61
0.79
98
4/2/00
31.8
34.7
1.1
97
3/16/00
48
55
1.153
98
4/3/00
34.5
37.6
1.2
97
3/17/002
-
60
1.1
-
4/4/00
34.6
38.4
1.4
96
3/18/00
52
59
1.3
98
4/5/00
34.1
39.3
1.4
96
3/19/00
51
58
1.3
97
4/6/00
32.7
36.4
1.5
95
3/20/00
50
55
1.4
97
4/7/00
40.1
42.8
1.3
97
3/21/00
47
54
1.4
97
4/8/00
38.9
43.4
1.3
97
3/22/00
46
53
1.4
97
4/9/00
38.7
42.3
1.3
97
3/23/00
46
53
1.5
97
4/10/00
19.4
43.3
1.5
92
3/24/00
44
50
1.4
97
4/11/00
38.7
43.7
1.3
97
3/25/00
44
51
1.1
98
4/12/00
40
44.3
42.92
NC
3/26/00
47
53
1.4
97
4/13/00
37.9
42.8
1.2
97
3/27/00
45
51
1.2
97
4/14/00
37.4
39.4
1.3
97
3/28/00
46.2
48.9
1.4
97
4/15/00
38.3
42.9
1.3
97
3/29/00
45.6
52.3
1.5
97
4/16/00
38.5
43.4
1.4
96
3/30/00
47.9
54.2
1.4
97
4/17/00
39.3
42.7
1.3
97
3/31/00
46.5
53.2
1.3
97
4/1/00
46.7
1.52
50.52
-
- No Data Reported
NC - Not calculated
(1) The reliability of the low level (MDL of 0.1 |ig/L to approximately 2|ig/L) should be considered as only
qualitative (not quantitative).
(2) Indicates likely mislabeled sample container of concentrate and/or permeate.
55
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Table 4-14: Dissolved Arsenic Data Summary
Feed
Concentrate
Permeate
Rejection
(Ug/L)
(Ug/L)1
(Ug/L)1
%
Average
42
48
1.3
97
Minimum
19.4
34.7
0.79
92
Maximum
52
61
1.5
98
Standard Deviation
7.0
7.4
0.15
1.0
Confidence Interval
(39, 44)
(45, 50)
(1.3. 1.4)
(96, 97)
(1) Summary calculations do not include concentrate and permeate results from April 1 and do not include permeate
results for April 12.
O)
3
C
o
C
a)
o
c
o
o
<
T3
C
TO
<
c
d)
T3
d)
>
O
tf)
b
60
50
\
Feed Water Concentration
Top three lines
40 -
30 -
10
o 4*=
Mm
/////////////////
Verification Testing Dates
¦ Dissolved As
¦Arsenic (III)
¦Arsenic (V)
¦ Permeate Dissolved As
Figure 4-4: Dissolved Arsenic Concentrations vs. Time
Note: Data from likely mislabeled containers are not included in this figure
56
-------
Arsenic (III)
In addition to collecting samples for total and dissolved arsenic, samples were also collected for
the speciation of arsenic present in the feedwater, concentrate, and permeate. As described in
Section 1.4, arsenic in natural waters is predominately present as either arsenic (HI) or arsenic
(V). Arsenic (V) is generally considered to be the dominant species in oxygenated waters.
Arsenic (ID) can be present in both ionic and nonionic form. There is some indication that arsenic
(HI) may not be rejected as easily as Arsenic (V). This may be due to the valence state or the
ionic form of arsenic (ID). It may also be dependent on the membrane material. For these reasons
it was determined that speciation of the arsenic should be part of the test program to provide data
on the individual species of arsenic, in addition to arsenic data for the total and dissolved
fractions. If it was found that a particular arsenic species was not rejected as efficiently, this
would be important in applying the process to different feed waters around the country.
Tables 4-15 and 4-16, and Figure 4-5 present the As (ID) removal characteristics of the KMS
TFC®-ULP4 Reverse Osmosis Membrane Element Module. The percent rejection was calculated
using the formula as shown in the operational formulae. A value of 0.5 |ig/l was used in the
calculation for the permeate concentration whenever the reported concentration was below the
MDL (0.5 |ig/l).
The data show that the membrane module was very effective in removing arsenic (ID) present in
the feed water. The feedwater had an average concentration of 8.0 |ig/l. Table 4-19 shows the
percentages of dissolved arsenic species in the feed water and concentrate. Arsenic (ID)
represents 19% of the dissolved arsenic present in the feedwater. Most of the permeate
concentrations are below 1.0 |ig/l and several are below the reported MDL of 0.5 |ig/l. Only two
samples were above 1.0 |ig/l, March 27 and April 12. The later day is the day where the samples
appear to have been mislabeled.
The results for Arsenic (HI) are very similar to those for Arsenic (V) reported later. These data
show that the KMS Module removed the arsenic (HI) contaminants in this feed water to levels
below 1 |lg/l. Further, the pH of the water was consistently in the 7.2-7.5 range, which would
indicate the arsenic (HI) present in the water was nonionic in form. The arsenic (ID) results
suggest that the KMS Module performance for rejection of arsenic is not impacted by the
presence of arsenic (HI) at the measured concentrations versus other species and forms of arsenic
in the feed water.
57
-------
Table 4-15: Arsenic (III) Data
Date
Feed
(lig/L)
Concentrate
(lig/L)
Permeate
(lig/L)
Rejection
%
Date
Feed
(lig/L)
Concentrate
(lig/L)
Permeate
(lig/L)
Rejection
%
3/15/00
-
-
-
-
4/2/00
13.3
8.1
0.5
96
3/16/00
-
-
-
4/3/00
12.7
2.8
<0.5
96
3/17/00
2.1
2.5
0.56
73
4/4/00
10.7
14.9
0.6
94
3/18/00
2.05
2.2
<0.5
76
4/5/00
2.6
2.5
0.5
81
3/19/00
-
-
-
-
4/6/00
2.5
2.7
0.5
80
3/20/00
-
-
0.67
-
4/7/00
2.5
2.5
0.5
80
3/21/00
2.2
2.1
0.69
69
4/8/00
2.3
2.2
<0.5
78
3/22/00
2.2
2.4
0.64
71
4/9/00
2.7
2.7
<0.5
81
3/23/00
26
26
0.87
97
4/10/00
2.7
2.6
0.5
81
3/24/00
5.1
6
0.54
89
4/11/00
2.6
2.8
0.5
81
3/25/00
12
7.1
0.56
95
4/12/00
2.6
2.7
2.4 3
NC
3/26/00
24
21
0.62
97
4/13/00
2.2
2.4
<0.5
77
3/27/00
25
17
2.3
91
4/14/00
2.6
2.2
<0.5
81
3/28/00
25.8
11.5
0.7
97
4/15/00
2.1
2.4
<0.5
76
3/29/00
2.1
2.2
0.5
76
4/16/00
2
2.2
<0.5
75
3/30/00
16.4
16.8
0.5
97
4/17/00
1.9
2.2
<0.5
74
3/31/00
12
17.5
0.7
94
4/1/00
13.7
13.6
<0.5
96
-No Data Reported
NC - Not calculated
1) The reliability of the low-level data (MDL of 0.1 |ig/L to approximately 2 |ig/L) should be considered as only
qualitative (not quantitative).
2) All calculations use the MDL value (0.5 |ig/ L) as the permeate value for all data reported below the MDL.
3) Indicates likely mislabeled sample container of permeate.
Note: Data are listed above exactly as received from the State Laboratory. Summary tables are rounded to 2 or 3
significant figures, as appropriate.
Table 4-16: Arsenic (III) Data Summary
Feed
Concentrate
Permeate
Rejection
(lig/L)
(lig/L)
Oig/L)1
%
Average
8.0
6.9
0.6
85
Minimum
1.9
2.1
<0.5
69
Maximum
26
26
2.3
97
Standard Deviation
8.2
6.9
0.3
10
Confidence Interval
(5.0, 11)
(4.4, 9.3)
(0.5, 0.7)
(81, 88)
(1) The permeate results for April 12 were not used in the summary calculations
58
-------
Figure 4-5: Arsenic (III) Concentration Data vs. Time
Note: Data from likely mislabeled containers are not included in this figure
Arsenic (V)
Arsenic (V) is normally the dominant species of dissolved arsenic found in natural oxygenated
waters. Therefore, the ability of an RO membrane module to reject arsenic and produce a high
quality permeate is dependent on the ability of the membrane to reject arsenic (V) species. Most
RO membranes are expected to reject multivalent ions more readily than monovalent ions and it
would be expected that arsenic (V) species should have a high level of rejection. However, it was
important for this verification test to measure and prove that the KMS Module could achieve a
high level of control.
Tables 4-17 and 4-18, and Figure 4-6 show the arsenic (V) results for the entire test period. Daily
results for the feed water, concentrate, and permeate are presented in Table 4-17 and summary
statistics are given in Table 4-18. The percent rejection for the KMS TFC®-ULP4 Reverse
Osmosis Membrane Element Module is calculated using the formula as shown in the operational
formulae.
The arsenic (V) results show that this species of arsenic represented 76% of the dissolved arsenic
present in the feed water (see Table 4-19). The feedwater concentration averaged 32 jj.g/1 with a
range of 16.7 to 50 |j.g/l. The KMS membrane module handled the arsenic (V) very effectively.
All permeate concentrations were 1 |J.g/l or less with an average concentration of arsenic (V) of
0.8 |ig/l. The variability was small with a maximum concentration of 1 |ig/l and minimum
concentration of <0.5 jj.g/1. There was one sample on April 12 reported at a value of 40.5 jj.g/1.
59
-------
which was similar to the concentrate and permeate for that day. The sample bottles were
apparently mislabeled or an improper sample collected on this day. The overall control for
arsenic (V) was excellent with an average removal of 97%.
Table 4-17: Arsenic (V) Data
Date
Feed
ftig/L)
Concentrate
ftig/L)
Permeate
(Hg/L)
Rejection
%
Date
Feed
(Ug/L)
Concentrate
(Ug/L)
Permeate
(Ug/L)
Rejection
%
3/15/00
-
4/2/00
18.5
26.6
0.6
97
3/16/00
-
-
-
-
4/3/00
21.8
34.8
0.7
97
3/17/00
-
57.5
0.54
-
4/4/00
23.9
23.5
0.8
97
3/18/00
49.95
56.8
0.8
98
4/5/00
31.5
36.8
0.9
97
3/19/00
-
-
-
-
4/6/00
30.2
33.7
1
97
3/20/00
-
-
0.73
-
4/7/00
37.6
40.3
0.8
98
3/21/00
44.8
51.9
0.71
98
4/8/00
36.6
41.2
0.8
98
3/22/00
43.8
50.6
0.76
98
4/9/00
36
39.6
0.8
98
3/23/00
20
27
0.63
97
4/10/00
16.7
40.7
1
94
3/24/00
38.9
44
0.86
98
4/11/00
36.1
40.9
0.8
98
3/25/00
32
43.9
0.54
98
4/12/00
37.4
41.6
40.54
NC
3/26/00
23
32
0.78
97
4/13/00
35.7
40.4
0.7
98
3/27/00
20
34
<0.5
98
4/14/00
34.8
37.2
0.8
98
3/28/00
20.4
37.4
0.7
97
4/15/00
36.2
40.5
0.8
98
3/29/00
43.5
50.1
1
98
4/16/00
36.5
41.2
0.9
98
3/30/00
31.5
37.4
0.9
97
4/17/00
37.4
40.5
0.8
98
3/31/00
34.5
35.7
0.6
98
4/1/00
33
<0.53
503
NC
- No result reported
NC - Not calculated
1) The reliability of the low-level data (MDL of 0.1 |ig/L to approximately 2|ig/L) should be considered as only
qualitative (not quantitative).
2) All calculations use the MDL value (0.5 |ig/ L) as the permeate value for all data reported below the MDL
3) Indicates likely mislabeled container of concentrate and/or permeate.
4) Indicates likely mislabeled container of permeate
Note: Data are listed above exactly as received from the State Laboratory. Summary tables are rounded to 2 or 3
significant figures, as appropriate
Table 4-18: Arsenic (V) Data Summary
Feed
Concentrate
Permeate
Rejection
(Ug/L)
(Ug/L)
(MS/L)1
%
Average
32
40
0.8
97
Minimum
16.7
23.5
<0.5
94
Maximum
49.95
57.5
1
98
Standard Deviation
8.7
8.1
0.1
1.0
Confidence Interval
(29, 36)
(37, 43)
(0.7, 0.8)
(97, 98)
60
-------
60
50 -
~
Feedwater Concentration
I
©
U
J
3
©
20 -
40 -
30 -
Permeate Concentration - All Values 1 ug/1 or less
10 -
I
^ ^ 4>- ^ ^y jr ^y jr ^y ^y ^y ^ ^ v v ^ ^
Verification Test Dates
(1) Summary calculations do not include concentrate and permeate results from April 1 and do not include
permeate results for April 12.
Figure 4-6: Arsenic (V) Concentration vs. Time
Note: Data from likely mislabeled containers are not included in this figure.
Arsenic Speciation Summary
As described in the preceding sections, the data collection tasks for this verification project
included the determination of total and dissolved arsenic, and speciation of the arsenic between
valence state 3 and 5. All of the daily and summary data have been presented in the previous
tables in this section. Table 4-19 summarizes these results and shows the percentages of the
various fractions of arsenic that were present in the feed water, concentrate, and permeate.
The data indicate that 70% of the arsenic in the feedwater was dissolved and 75% of the arsenic
in the concentrate was in the dissolved form. Arsenic (V) represented 76% of the dissolved
arsenic in the feed water and 83% of the dissolved arsenic in the concentrate. All the permeate
data is near the quantitation limit for the test as mentioned previously. Therefore the actual
percentages of the two arsenic species should be considered estimates. Arsenic (IE) in the
permeate represented approximately 46% of the dissolved arsenic and Arsenic (V) represented
approximately 62% of the dissolved arsenic in the permeate water.
This final summary of the data by species shows that the membrane module operated at a high
rejection percentage and generated permeate with a low concentration of all arsenic species.
61
-------
Table 4-19: Percentage of Various Arsenic Species Based on Summary Average
Values
Feed
Percent of
Percent of
Concentrate
Percent of
Percent of
Permeate
(lig/L)
Total As
Dissolved
(lig/L)
Total
Dissolved
(lig/L)
As
As
As
Total As
60
NA
NA
64
NA
NA
0.9
Dissolved As
42
70%
NA
48
75%
NA
1.3
As (III)
8.0
NA
19%
6.9
NA
14%
0.6
As (V)
32
NA
76%
40
NA
83%
0.8
NA = Not applicable.
Note: Percentages do not total 100% because data are averages.
Total Arsenic Mass Balance
In order to examine possible retention of arsenic within the module, summaries of the mass
balances for total and dissolved arsenic, using measured flow rates and laboratory analytical data
are listed in Table 4-20 below. The daily calculations used to develop these summaries are
presented in tables in Appendix G. The formula used to calculate the mass balance is as follows:
Qf Cf = Qc Cc + Qp CP
Where:
QF = Feed Flow Rate (1/day) CF = Feedwater Concentration (mg/1)
Qc = Concentrate Flow Rate (1/day) Cc = Concentrate Concentration (mg/1)
QP = Permeate Flow Rate (1/day) CP = Permeate Concentration (mg/1)
The actual daily mass of arsenic in the feed water, concentrate, and permeate was calculated by
converting the flow rate in gallons per minute to liter per day (3.785 1/gal; 60 min/hr; 24 hrs/day).
The mass in micrograms was converted to milligrams by dividing by 1000. If all of the arsenic
present in the feedwater exited the membrane module, then the sum of the mass in the
concentrate and permeate waters should be equal to the mass of arsenic in the feedwater. The
difference or possible retention of arsenic in the system was calculated by subtracting the arsenic
measured in the concentrate and permeate waters from the feedwater. Permeate mass calculations
assumed that arsenic was present at 0.5 |ig/l for all values reported as <0.5 |ig/l (MDL).
The mass balances show that on all but four days (March 24, April 6, 7 and 8) the total arsenic
entering the system was higher than the mass of total arsenic exiting the system. Mass balances
show that the same was true for dissolved arsenic on all but four days (March 15, 22 and 27,
April 10) of operation. Over the thirty-four day test period the amount of total arsenic
unaccounted for in the mass balance is 6,300 mg (based on thirty three days of data), which
represents approximately 8% of the total arsenic in the feed water. In the case of dissolved
arsenic, the unaccounted for quantity in the mass balance is 890 mg (based on thirty one days of
data), which represents approximately 1.8% of the dissolved arsenic in the feed water.
The mass balances are good given all of the assumptions that are required to perform the
calculations. There is some indication based on the pattern of the data, i.e. the slow drop-off in
specific flux and the slight difference between dissolved arsenic percentages in the concentrate
62
-------
compared to the feedwater, that some arsenic in the particulate form may be trapped in the
membrane. This will be discussed further below.
Table 4-20: Summary of Total and Dissolved Arsenic Mass Balances
TOTAL ARSENIC
Total Mass
Total Mass
Total Mass
Mass
Feed
Concentrate
Permeate
Difference
(¦lift)
(in8)
(in8)
(in8)
77,000
71,000
150
6,300
DISSOLVED ARSENIC
Total Mass
Total Mass
Total Mass
Mass
Feed
Concentrate
Permeate
Difference
(¦lift)
(in8)
(in8)
(in8)
50,000
49,000
220
890
The unaccounted total arsenic in the mass balances may be a result of several factors, including
sample collection method, laboratory variation, and retention of arsenic within the module. The
samples collected during this test were instantaneous grab samples and only truly represent a
moment in time. Therefore, there can be some error induced when converting these data to daily
representations of the total mass of arsenic processed in the module. Laboratory variation can
also be expected to influence daily mass balance calculation. Typical precision for arsenic
measurements by ICP-MS is + 30% as defined in the Quality Assurance Plan. While normal
analysis is expected to be somewhat better than + 30%, the QA criteria for acceptable data was
set at this precision level. While sample collection and laboratory variation can be expected to
influence the daily mass balance calculation, it would typically be expected that the variation
would on both the high and low side of the mass calculation. Unless the sample matrix for the
feed water is biased high for all samples, and/or the concentrate and permeate are biased low for
all samples, it would not appear that all of the unaccounted for arsenic can be attributed to
sample and laboratory variation.
Given the consistent "loss" of arsenic in the mass balance calculation, it is suspected that some
arsenic is being retained within the membrane module in particulate form. Some of the insoluble
arsenic (about 30 % of the total) is most likely being trapped in the membrane and the membrane
is acting as a filter to remove and retain this material. The discussion, "Fouling Issues", later in
this section, presents the case for possible minor iron fouling, based on the analysis of the
module cleaning solution. The Ligand exchange mechanism, known to facilitate arsenic removal
in the presence of ferric hydroxide coagulant chemistries, may account for some arsenic
reduction as the feedwater analyses show the presence of small concentrations of iron in the
incoming water.
It should be emphasized that the overall performance of the membrane module throughout the
duration of this test was unaffected by any accumulation of insoluble material, regardless of its
source. Daily monitoring of the unit did show a slow steady decline in specific flux (20%
decrease, from 0.25 gfd/psi to a low of 0.20 gfd/psi) over the duration of this test. There were no
fast or abnormal changes in flows or pressure over the 34-day period. The unit was cleaned at the
63
-------
end of the test to verify cleaning procedures. While cleaning was not absolutely needed at that
time, the decline in specific flux and permeate flow rate indicated that cleaning would be needed
within a short period of time.
The importance of recognizing the possible retention of arsenic and other insoluble material
within the membrane is that fouling of membranes by insoluble materials is a primary cause of
high maintenance cost, frequent cleaning requirements or even membrane failures. Therefore, it
is important to recognize these potential issues when selecting this type of technology for a
specific water treatment application.
Summary of Arsenic Results
The total arsenic concentration in the feedwater averaged 60 |ig/L over the thirty-four day test
period. The Koch membrane module reduced total arsenic to an average of 0.9 |ig/L in the
permeate. The Koch membrane module reduced the dissolved arsenic in the feedwater from an
average of 42 |ig/L to less than 1.3 |ig/L in the permeate. The dominant arsenic species in the
Spiro Tunnel feed water was As (V). The feedwater average concentration of Arsenic (V) was 32
|ig/L and was reduced to an average level of 0.8 |ig/L in the treated water. Arsenic (V)
represented 76% of the dissolved arsenic present in the feed water. Arsenic (HI) was also rejected
by the membrane, reducing the average feedwater level of 8 |ig/l to 0.6 |ig/l in the permeate.
In all cases the permeate concentrations were below the current EPA MCL of 50 |ig/l and below
the proposed standard of 10 |ig/l that is currently under review. The KMS Module effectively and
consistently removed/rejected all forms of arsenic present in the feedwater.
Antimony Removal
The Park City Municipal Corporation had expressed concern about elevated levels of antimony
in the Bulkhead water source, so the daily water analyses included antimony data. The
membrane consistently removed antimony to below the minimum detection level (MDL) of 3.0
|ig/L. Table 4-21 lists the daily concentrations of antimony in all three streams (feed, concentrate
and permeate) and these data are plotted in Figure 4-7. Table 4-22 presents the antimony
summary data. All of the antimony permeate concentrations were below 3.0 |lg/L, the reported
MDL. The maximum antimony feed water concentration was 9.1 |ig/l and the MDL was 3.0 |ig/l;
therefore, the maximum rejection percentage that could be calculated was 67%.
64
-------
Table 4-21: Antimony Concentrations in Feed, Concentrate and Permeate Streams
Antimony Readings (|ig/L)
Date
Feed
Concentrate
Permeate2
3/15/00
00
00
11.0
<3.0
3/16/00
8.6
10.0
<3.0
3/17/00
8.5
9.9
<3.0
3/18/00
9.0
10.0
<3.0
3/19/00
8.7
9.8
<3.0
3/20/00
8.7
10.0
<3.0
3/21/00
9.0
10.0
<3.0
3/22/00
8.6
9.7
<3.0
3/23/00
8.4
9.9
<3.0
3/24/00
8.4
9.9
<3.0
3/25/00
8.4
9.8
<3.0
3/26/00
8.2
9.6
<3.0
3/27/00
8.4
9.7
<3.0
3/28/00
9.0
10.6
<3.0
3/29/00
9.0
10.6
<3.0
3/30/00
8.4
9.8
<3.0
3/31/00
8.7
10.2
<3.0
4/1/00
8.7
10.1
<3.0
4/2/00
8.6
10.0
<3.0
4/3/00
8.5
9.9
<3.0
4/4/00
8.4
10.1
<3.0
4/5/00
8.6
9.9
<3.0
4/6/00
8.6
9.9
<3.0
4/7/00
8.5
10.2
<3.0
4/8/00
9.0
9.9
<3.0
4/9/00
8.6
10.2
<3.0
4/10/00
8.7
10.0
<3.0
4/11/00
8.4
9.7
<3.0
4/12/00
00
00
10.6
10.3 1
4/13/00
9.1
10.5
<3.0
4/14/00
00
00
10.2
<3.0
4/15/00
8.9
10.3
<3.0
4/16/00
9.0
10.2
<3.0
4/17/00
8.9
10.3
<3.0
Permeate sample most likely mislabeled or incorrect sample taken.
Laboratory reported MDL was 3.0 (|ig/L)
65
-------
Table 4-22: Antimony Summary Data
Feed
Concentrate
Permeate ' ~
(Ug/L)
(Ug/L)
(Ug/L)
Average
8.7
10.1
3.0
Minimum
8.2
9.6
<3.0
Maximum
9.1
11
<3.0
Standard Deviation
0.24
0.31
0.0
Confidence Interval
(8.6, 8.8)
(10.0, 10.2)
NC
NC - Not calculated
(1) Permeate summary based on using the value 3.0 |ig/L for all results
Reported as < 3.0 |Jg/L.
(2) Permeate result from April 12 not used in summary calculation
10
Verification Test Dates
Figure 4-7: Antimony Concentration versus Time
Note: Data from likely mislabeled containers are not included in this figure
pH Readings
pH measurements of the feed, concentrate and permeate streams were made on-site on a daily
basis. The permeate pH is virtually always lower than the feed pH because reverse osmosis
technology removes salts, thereby reducing the buffering capacity. Also, the higher purity, more
aggressive property of the permeate results in dissolution of carbon dioxide from the air, forming
carbonic acid in the relatively unbuffered water and lowering the pH. Table 4-23 lists these data,
Table 4-24 summarizes these data and Figure 4-8 graphically represents these data.
66
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Table 4-23: pH Data
Readings
Date
Feed
Concentrate
Permeate
3/15/00
7.35
7.37
5.94
3/16/00
7.40
7.50
5.89
3/17/00
7.48
7.49
5.73
3/18/00
7.60
7.57
6.66
3/19/00
7.58
7.58
5.5
3/20/00
7.41
7.36
5.72
3/21/00
7.3
7.36
5.62
3/22/00
7.37
7.39
5.84
3/23/00
7.32
7.42
5.74
3/24/00
7.22
7.36
5.87
3/25/00
7.28
7.35
5.73
3/26/00
7.24
7.38
5.97
3/27/00
7.21
7.35
5.89
3/28/00
7.27
7.39
5.74
3/29/00
7.19
7.32
5.57
3/30/00
7.23
7.36
5.89
3/31/00
7.27
7.37
6.0
4/1/00
7.35
7.29
6.58
4/2/00
7.28
7.35
5.66
4/3/00
7.33
7.30
5.84
4/4/00
7.27
7.33
6.08
4/5/00
7.31
7.32
6.28
4/6/00
7.33
7.36
6.31
4/7/00
7.27
7.41
6.42
4/8/00
7.44
7.47
6.05
4/9/00
7.24
7.34
5.83
4/10/00
7.30
7.37
5.56
4/11/00
7.23
7.29
6.07
4/12/00
7.23
7.33
6.15
4/13/00
7.22
7.31
6.45
4/14/00
7.22
7.22
5.53
4/15/00
7.29
7.35
6.18
4/16/00
7.29
7.36
5.90
4/17/00
7.32
7.35
5.89
Table 4-24: pH Data Summary
Feed
Concentrate
Permeate
Average
7.31
7.37
5.94
Minimum
7.19
7.22
5.5
Maximum
7.60
7.58
6.66
Standard Deviation
0.0977
0.0750
0.297
Confidence Interval
(7.28, 7.35)
(7.35, 7.40)
(5.84, 6.04)
67
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j 5.00 -
M 4.50 -
c.
4.00 -
3.50 -
3.00 -
Verification Test Dates
Feed Concentrate —A— Permeate
Figure 4-8: pH Measurements over Testing Period
Fouling Issues
The iron concentration in the Spiro Tunnel Bulkhead water supply ranged from 0.118 to 0.255
mg/L (one day showed 1.68 mg/1, which was considered an outlier), which is considered to be of
moderate concern in a spiral-would reverse osmosis membrane system (iron concentrations
above 0.3 mg/L require pretreatment). These iron concentrations were measured after the 5
micron prefilter and do not represent the iron that may be present in the raw bulkhead water. The
decrease in permeate rate (1.10 gpm to 0.90 gpm) and specific flux (20% decrease) during the
length of the test may be the result of iron hydroxide fouling. Ferric hydroxide will readily form
in an oxidizing environment at neutral or higher pH levels. It is one of the most common
contributors to membrane fouling in groundwater treatment applications. Fortunately, Fe (OH)3
foulants can be readily removed with acidic cleaning solutions.
Table 4-25 lists the iron data collected during this test. The KMS Module effectively rejected
iron, yielding a permeate with less than 0.02 mg/1 iron. Given the good rejection of iron by the
membrane unit, it would be expected that the iron concentration in the concentrate would
increase and be higher than the feed water. As can be seen in Table 4-25, this is not the case. In
similar manner as was described earlier for the total arsenic data, mass balances were performed
for the iron data to more closely evaluate the results.
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Table 4-25: Iron Concentrations
Date
Feed
Concentrate
Permeate (mg/L)
(mg/L)
(mg/L)
3/20/00
0.255
0.195
<0.02
3/27/00
1.681
0.111
<0.02
4/4/00
0.16
0.107
<0.02
4/10/00
0.161
0.104
<0.02
4/17/00
0.118
0.106
<0.02
(l) Value questionable - 0.168 mg/1 used in the mass balance calculations below
Table 4-26 shows the results for the mass balance calculations. The iron result for March 27
(1.68 mg/1) is an order of magnitude above all the other data collected during this test. Also, this
value is very high compared to other iron data (0.128 mg/1) collected on this same date as part of
a separate project. Based on this information it was assumed that the actual concentration was
0.168 mg/1 for the mass balance calculations. The same formula and conversion factors that were
used for arsenic calculations were used for these calculations. Flow data were converted to liters
per day and sample results were assumed to represent a twenty-four hour period. The mass of
iron present in the water streams could then be compared and balanced on a daily basis. As can
be seen, the mass of iron entering the system on each of the four monitoring days is consistently
higher than the mass of iron exiting the system in the concentrate and permeate.
Table 4-26: Estimated Mass of Iron Retained in Module
Date
Feed Mass
QfCf
(mg/day)
Concentrate Mass
QcCc
(mg/day)
Permeate Mass
QpCp
(mg/day)
Difference
Feed- (Concentrate +
Permeate)
(mg/day)
3/20/00
10,600
7010
113
3490
3/27/00
6510
3660
116
2730
4/4/00
6070
3490
106
2480
4/10/00
6070
3380
103
2590
4/17/00
4410
3420
101
880
Qf = Feed Flow Rate (L/day) Cf = Feedwater Concentration (mg/L)
Qc = Concentrate Flow Rate (L/day) Cc = Concentrate Concentration (mg/L)
Qp = Permeate Flow Rate (L/day) Cp = Permeate Concentration (mg/L)
The last column of Table 4-26 shows the estimated amount of iron that may be retained within
the module. These data show that an average of approximately 2430 mg of iron is retained each
day. Using the average of the four data points and multiplying by the 34-day test period, it can be
estimated that approximately 83 grams of iron may be retained within the module.
These results are only approximations for three reasons:
1) Every permeate reading was below the MDL (0.02 mg/L) for iron. The calculation assumed
that the total iron concentration in the permeate was 0.02 mg/L, but it may have been much
less.
69
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2) The analyses measured total iron, rather than Fe(OH)3 The actual compound that precipitated
was probably a complexed ferric hydroxide, with possibly one or more As (V) ions attached,
as it is well known that ferric hydroxide will exchange one or more OH" ions for As (V) ions
(Ligand exchange).
3) The calculations for the retention of iron for the entire test period are based on only four data
points. The iron results did vary and the assumption that the average of the data points
represents the entire test period could be significantly biased. Also, the one high feedwater
concentration was assumed to be an outlier and not typical of the actual feedwater
concentration.
Additional data on possible iron precipitation are available from the analysis of the membrane
cleaning solution following the cleaning operation on April 17. Total iron was measured in the
cleaning solution and found to be present at 466.0 mg/L. Reverse osmosis permeate was used to
prepare the cleaning solution so there was little or no iron added from the makeup water. The
Certificate of Analysis for the citric acid shows the iron concentration to be "<50 mg/kg."
Assuming an iron concentration of 50 mg/kg to be present, this would contribute only 0.193g
iron to the cleaning solution. A reasonable conclusion, therefore, is that the membrane module
retained a considerable quantity of iron.
The cleaning solution used during this test was used to clean two different modules from separate
manufacturers. Based on the concentration of total iron in the 50 gallons of spent cleaning
solution, a total of 88 grams of iron was extracted from the two different modules. If it is
assumed that equal amounts of iron were extracted from each module, then a total of 44 grams of
iron would be attributed to the Koch module. The mass balance calculation, reported above,
showed the estimated accumulation of iron was 83 grams for the 34-day period.
The data strongly suggest that some accumulation of iron, probably as iron hydroxide was
occurring throughout the test. The steady decrease in permeate rate and specific flux also
indicates that some type of fouling was occurring slowly over time. Iron fouling of RO
membrane units is a common occurrence and can be expected. In the case of the KMS Module,
any iron accumulation or fouling that was occurring during the test period was handled without
any significant impact on arsenic removal. Given these test results, it could be expected that the
KMS Module would require cleaning due to an accumulation of iron and other contaminants
within the membrane. The decrease in permeate flow rate over the 34 days approached the point
at which the module would require cleaning. The cleaning cycle test showed that the iron and/or
other fouling constituents could be removed from the module and operating conditions restored
to original "clean" membrane conditions.
Other Parameters
On a weekly basis, samples were submitted to the State Laboratory to be analyzed for the
following parameters:
• Fluoride
• Total iron
• Manganese
• Sulfate
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The Test Plan required the parameters listed below to be measured once during the one-month
duration of the test:
• Alkalinity
• LSI
• Turbidity
• TSS
• TOC
• Silica (total)
In addition, the following parameters were measured during the test period:
• Magnesium
• Chloride
The above data are summarized in Table 4-27. It should be noted that virtually all permeate
readings were at or below the MDL for almost all of the parameters. The Koch membrane
module was very effective in rejecting all of the salts and other contaminants that were monitored
to describe overall water quality. The permeate produced from the unit showed excellent water
quality.
The operational data indicate that no significant fouling occurred during the test period. A
quantity of precipitated iron was recovered from the module, but it would appear that none of the
other parameters listed in Table 4-27 had an effect on the KMS Module performance.
71
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Table 4-27: Weekly Analytical Parameters
Date
Fluoride (mg/L)
Iron (total)(mg/L)
Manganese (|ig/L)
Feed
Cone.
Perm.
Feed
Cone.
Perm.
Feed
Cone.
Perm.
3/20/00
0.18
0.21
<0.05
0.255
0.195
<0.02
22.6
18.3
<5
3/27/00
0.17
0.2
<0.05
1.68
0.111
<0.02
26.1
14.9
<5
4/4/00
0.156
0.186
<0.05
0.16
0.107
<0.02
13.6
15.6
<5
4/10/00
0.161
0.186
<0.05
0.161
0.104
<0.02
13.3
15.2
<5
4/17/00
-
-
-
0.118
0.106
<0.02
14.4
15.4
<5
Date
Sulfate (mg/L)
Alkalinity (mg/L)
LSI (L.Ind.)
Feed
Cone.
Perm.
Feed
Cone.
Perm.
Feed
Cone.
Perm.
3/20/00
268.4
314.1
<20.0
-
167
5
0.32
0.52
-4.32
3/27/00
284.0
303.0
<20.0
-
-
-
-
-
-
4/4/00
270.0
287.0
<20.0
-
-
-
-
-
-
4/10/00
274.0
292.0
<20.0
-
-
-
-
-
-
4/17/00
-
-
-
147
166
4
-
-
-
Turbidity (NTU) TSS (mg/L) Silica (total)(mg/L)
Feed
Cone.
Perm.
Feed
Cone.
Perm
Feed Cone.
Perm.
3/20/00
1.44
1.2
<0.1
<4.0
<4.0
<4.0
22.1
<1.0
3/23/00
-
-
-
-
-
-
23.9,23.0
<1.0, <1.0
4/17/00
0.32
0.35
0.10
-
-
-
19.5 22.2
<1.0
TOC (mg/L)
Magnesium (mg/L)
Chloride (mg/L)
Feed
Cone.
Perm.
Feed
Cone.
Perm.
Feed Cone.
Perm.
3/20/00
<0.5
<0.5
<0.5
-
-
-
-
-
4/4/00
-
-
-
39.5
45.6
<1.0
-
-
4/17/00
<0.5
<0.5
<0.5
-
-
-
5.5 7
<3
- No Data Reported
4.4 Results of Equipment Characterization
During verification testing, the factors associated with the qualitative, quantitative and cost
characteristics of the equipment were identified, within the limits of the short duration of the test.
4.4.1 Qualitative Factors
The qualitative factors examined were the susceptibility of the equipment to environmental
condition changes, operational reliability and equipment safety.
4.4.1.1 Susceptibility to Changes in Environmental Conditions
Changes in environmental conditions that cause changes in feedwater quality can affect the
performance of reverse osmosis membrane modules. Since the rejection of dissolved salts is
always a percentage of the concentration of salts at the membrane surface, any changes in the
feedwater concentration will affect permeate quality. As long as the salts remain soluble, they
will not degrade the membrane.
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Suspended solids in the feedwater are generally effectively removed by the 5|i prefilter
cartridges; however, if filter break-through occurs or the cartridges become so loaded as to
reduce flow through them, the membrane element modules can become fouled. Fouling can also
occur in that the concentration effects of the reverse osmosis equipment can cause precipitation
of insoluble salts. If excessive fouling occurs, chemical cleaning may not restore the flux to an
adequate level and the membrane elements will require replacement.
In this test, in spite of the wide variation in SDI readings after the prefilter cartridges (Table 4-6,
Figure 4-2), the membrane element module required cleaning only at the end of the test period,
and the performance was completely restored by the cleaning operation.
Since the water source was groundwater, even though ambient conditions were changing, the
feedwater temperature remained unchanged throughout the test. Also, the test unit was located
indoors, so it was unaffected by weather changes.
4.4.1.2 Operational Reliability
The equipment ran continuously throughout the duration of the test, meaning that the high-
pressure pump was running during this time. It was turned off for approximately five minutes at
a time for prefilter cartridge replacement.
From system startup until April 2, the prefilter cartridges were replaced every other day. During
the night of April 1, a turbidity spike to almost 12 NTU resulted in the cartridges becoming so
fouled as to cause the membrane pressures to drop to 50 psi (there was no evidence that any other
chemical parameter caused the fouling). Replacing the filter cartridges eliminated the problem,
and from that day until the termination of the test on April 17, the cartridges were changed daily.
The cleaning, which took place on April 17, was performed manually.
The daily changing of the prefilter cartridges was established after April 1 turbidity spike to
ensure that the Rosy-200 pilot test unit would be able to maintain feedwater pressure on a
continuous basis. On-site support for monitoring the prefilter status (manual prefilter unit) was
only available during the daytime periods. Thus, frequent changing of the prefilter was performed
whether or not there were any signs of pressure drop or plugging. It would be expected that an
automated pre-filter system or 24 hour staff coverage would be available in a full-scale water
plant. Based on the typical turbidity levels monitored on most days it could be expected that
prefilter cartridge life would be much longer than one day. The actual prefilter changing
schedule will be dependent on the quality of the water supplied to the prefilter cartridge system.
Once flows, pressures and water recovery conditions were established during the Initial
Operations Period, no adjustments were made throughout the duration of the test.
4.4.1.3 Equipment Safety
Evaluation of the safety of the treatment system was done by examination of the components of
the system and identification of hazards associated with these components. A judgment as to the
safety of the treatment system was made from these evaluations.
73
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There are safety hazards associated with high voltage electrical service and pressurized water.
The electrical service was connected by a qualified electrical contractor according to local code
requirements and did not represent an unusual safety risk. The water pressure inside the
treatment system was 150 psi. All personnel were cautioned not to stand at the ends of the
pressure vessel (membrane housing). The pressure vessel was manufactured and tested to ASME
standards for a maximum operating pressure of 300 psi.
The cleaning chemical, citric acid, is a hazardous chemical. The use of appropriate personal
protective equipment (PPE) minimizes the risk of exposure to this substance. The prompt and
proper clean up of spills minimizes the hazards associated with this chemical.
No injuries or accidents occurred during the testing.
4.4.2 Quantitative Factors
Quantitative factors examined during the verification testing were power, consumables, waste
disposal and length of operating cycle.
4.4.2.1 Electrical Power
The electrical power used was 230VAC, 3 phase, 20A service. The total power used was
recorded on an Amprobe Kilowatt/Hour Meter (non-demand). The total power consumed was
232.5 kWh. Since two membrane element modules were tested simultaneously and both run at
the same pressure, it is assumed that each module consumed one-half of the total power, or
116.25 kWh, which included the Initial Operations Period. From March 15 though April 17,
181.48 [2011.558-2.484)]/2=90.74 Kwh of electricity was consumed by the KMS TFC -ULP4
Reverse Osmosis Membrane Element Module, or 2.84 Kwh per day. If the five minutes per day
for filter cartridge replacement are ignored, the electrical usage was 0.118 Kwh per hour.
4.4.2.2 Consumables
The consumables included prefilter cartridges and the citric acid cleaning chemical. The prefilter
cartridge requirement was one 5|i (nominal) 20" long cartridge per day (one for each module
tested). The citric acid cleaning chemical was USP/FCC quality. The quantity required was a
2% (wt/wt) solution (8.5 lb/50 gallons permeate) per module.
If pH adjustment to minimize calcium carbonate formation was utilized, approximately 1.8 Lb
per day of HC1 would be required for a unit operating at 80% recovery
4.4.2.3 Waste Disposal
The wastes generated during the verification testing period were the concentrate stream at
approximately 6 gpm (276,500 gallons total) and 50 gallons of cleaning solution (citric acid and
water). Both were directed to the Snyderville Sewer Improvement District, which treats all
wastewater from the Park City Municipal Corporation. The citric acid cleaning solution was
diluted with reverse osmosis concentrate to meet the regulated pH discharge standard.
74
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4.4.2.4 Length of Operating Cycle
Spiral-wound reverse osmosis membrane element modules are designed to operate continuously,
if possible. The pretreatment requirements and chemical cleaning frequency are dictated by the
feedwater quality. For this water supply, 5|i (nominal) filter cartridges provided sufficient
prefiltration, and to prevent irreversible fouling, a chemical cleaning frequency of once per
month proved to be adequate. In a large automated system, a "fast flush" feature would be
incorporated. This feature automatically flushes the membrane surfaces at low pressure and low
recovery for about 10 minutes normally once per day.
4.5 QA/QC Results
The results of QA/QC verification performed on in-line instrumentation, hand-held instruments
and the analytical Laboratory are presented below.
4.5.1 In-Line Thermometer
Temperatures were measured in accordance with SM 2550 two times daily, with a Tel-Tru NIST
traceable thermometer mounted in the pipe between the high-pressure pump and the membrane
element module. The temperature read a constant 49°F (9.4°C) throughout the duration of the
test.
4.5.2 Conductivity Monitor
The hand-held Myron L Ultrameter Model P (serial #6 EVAL) conductivity monitor was sent to
the manufacturer for calibration prior to the start of the verification testing. On a daily basis, the
monitor was also calibrated with standard solutions from the manufacturer: 18, 170 and 700
|is/cm conductivity. This monitor was used to obtain the conductivity data for osmotic pressure
calculations. The certificates of calibration for the conductivity monitor and NIST traceability
are located in Appendix F.
4.5.3 Pressure Gauges
Pressure gauges were originally mounted on the inlet and outlet of the 5|i prefilter housing as
well as on the feed and concentrate sides of the membrane element model. An evaluation of the
accuracy of these gauges revealed that they all were inadequate, so the gauges were removed and
replaced with quick-disconnect fittings to allow all pressure readings to be made with glycerin-
filled NIST traceable gauges installed for each reading. The prefilter pressures were read with a
0-60 psig Ametek Module No. 1980L (Certificate #0084-6); the membrane pressures were read
with a 0-200 psig Ametek Model 1980L (Certificate #0068-7). Certificates of calibration are
located in Appendix F.
4.5.4 Flow Monitoring
The test unit was equipped with panel mounted acrylic flow meters to read permeate and
concentrate flow rates; however, the accuracy of these meters was determined to be too poor to
use, so the "bucket and stopwatch" flow rate procedure was utilized for all flow measurements.
75
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The permeate and concentrate lines were equipped with three-way valves which allowed the total
flow to be diverted for these measurements, which were made two times per day.
4.5.5 pH Meter
pH readings were made in accordance with SM 4500-H+ on an Oakton® WD-35615-Series
meter. A three-point calibration (pH 4, 7 and 10) with NIST traceable pH buffers was performed
daily. Between tests, the pH probe was kept wet in KC1 solution. Field procedures were used to
limit the absorbance of carbon dioxide to avoid skewing results by poorly buffered water.
The unit was calibrated against a standardized pH instrument in the State of Utah Laboratory and
found to be within 5% accuracy.
4.5.6 Turbidity Instrumentation
Turbidity readings were required only once per month; however, readings on the raw water
(before filter cartridges) were taken almost daily from the Spiro Treatment Plant wall mounted
in-line turbidimeter (HF Scientific, Inc, Micro 200) and also measured with a Hach 21 OOP
benchtop turbidimeter. The benchtop turbidimeter was calibrated at the start of testing and then
weekly against primary standards. Manufacturer's procedures for maintenance were followed
and the schedules for maintenance and cleaning noted in the logbook. All glassware was
dedicated and cleaned with lint free tissues to prevent scouring or deposits on the cells.
Secondary standards (0.0, 0.4 and 20.0 NTU) were used to calibrate the turbidimeter with each
use. Standard Methods 2130 was employed for measurement of turbidity.
Disturbances in the tunnel resulted in wide variances in turbidity readings, including the
occasional spike. The wall-mounted meter was scheduled to be cleaned weekly, although the
data indicate that this may not have been frequent enough.
The State Laboratory analyzed the membrane feed, concentrate and permeate stream turbidities
twice during the period of the test. In both cases, the permeate turbidity was at or below the
minimum detection level of 0.1 NTU.
4.5.7 Tubing and Fittings
The tubing and fittings associated with the treatment system and wall mounted turbidimeter were
inspected to verify that they were clean and did not have any holes or cracks in them. Also, the
tubing was inspected for brittleness or any condition, which could cause failure.
4.5.8 Off-Site Analysis of Chemical Samples
4.5.8.1 Organic Parameters (Total Organic Carbon)
TOC was required to be measured once per month. A total of nine samples were collected on
March 20 and April 17. Four samples were improperly preserved; however, all results were
below the MDL of 0.5 mg/L.
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4.5.8.2 Inorganic Samples
Inorganic samples were collected, held in the refrigerator at 4°C and delivered in accordance with
SM 3010B and C and 1060 and EPA §136.3, 40 CFR Ch I, at least twice a week. Proper bottles
and preservatives, where required (iron and manganese for example), were used. Although the
travel time was brief, samples were shipped in coolers at 4°C. Results of all off-site analyses are
listed in Appendix D.
4.5.9 SDI Measurements
SDI (Silt Density Index) measurement of the feedwater stream was required to be made once per
month. In actuality, nine measurements were made, commencing on March 15 and ending on
April 17.
4.5.10 Arsenic Speciation and Analysis
On a daily basis, feed, concentrate and permeate samples were collected and speciated on-site.
All samples were then delivered to the State Laboratory for analysis. The laboratory analyzed for
total arsenic, dissolved arsenic and As (HI). As (V) data were obtained by subtracting As (in)
readings from the dissolved arsenic figure.
In almost all permeate samples, the dissolved arsenic figures were higher than the total arsenic
figures. The State Laboratory investigated this anomaly in detail and postulates that the presence
of the H2SO4 preservative in bottle b (bottles a and c had HNO3 preservative) affected the
accuracy of the ICP-MS analytical equipment. This explanation, arsenic speciation protocol and
Laboratory QA/QC procedures are detailed in Appendices C and I.
The Quality Control review by NSF raised the question of whether or not the laboratory could
actually document a reporting limit of 0.5 |ig/l for total arsenic, dissolved arsenic and the arsenic
species. The reviewer indicated in the review comments that the sulfate interference had not been
proven in his opinion. It was also stated that a reporting limit (actual quantitation limit) is
typically 10-30 times the MDL. Therefore, a reporting of limit of 3-5 |ig/l may be more
appropriate. At this level, all of the data would be reported as "less than values" for the permeate
and the difference between the total and dissolved arsenic would be eliminated.
77
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Chapter 5
References
References consulted in the preparation of this Environmental Technology Verification Report
include the following:
"Health Implications of Arsenic in Drinking Water", Pontius, F.W., Brown, K.G., Chen, C.J.,
Journa\AWWA, September 1994.
"Chemistry of Arsenic Removal During Coagulation and Fe-MN Oxidation", Edwards, M.,
Journa 1AWWA, September, 1994.
"Enhanced Coagulation For Arsenic Removal", Cheng, R.C., Liang, S., Want, H.C., Beuhler,
M.D., JournaIAWWA, September, 1994.
"POU/POE Technologies Available For Arsenic Removal", Russo, R., Water Technology,
August, 1998.
"Chromatography Aids in Arsenic Removal", Badger, T.J., Bergemamann, E.P., Smith, P.K.,
Datta, R., Water Technology, August 1999.
"Arsenic Removal in the 1990's: Full Scale Experience from Park City Utah", Gibbs, J.W.,
Scanlan, L.P., Proceedings WQTC, November 1994.
"Crossflow Filtration for Environmental Compliance", Cartwright, P, (P.E.), Filtration and
Separation, October 1997
NSF/EPA Test Plan: Chapter 2, NSF Equipment Verification Testing Plan For The Removal of
Inorganic Chemical Contaminants By Reverse Osmosis Or Nanofiltration, NSF International,
Ann Arbor, Michigan, June 18, 1999.
NSF/EPA Protocol: Chapter 1, Protocol of Equipment Verification Testing For Arsenic Removal,
NSF International, Ann Arbor, Michigan, May 28, 1999.
Standard Methods for the Examination of Water and Wastewater, 20th edition, (APHA, et. al.,
1998)
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