June 2001
NSF 01/28/EPADW395
Environmental Technology
Verification Report
On-Site Disinfectant Generation and
Inactivation of Pseudomonas in Raw
Drinking Water
OXI-2B
OXI Company, Inc.
Prepared by
®
NSF International
Under a Cooperative Agreement with
U.S. Environmental Protection Agency
eiVetVeiV
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION
PROGRAM
«* ®
U.S. Environmental Protection Agency NSF International
ETV Joint Verification Statement
TECHNOLOGY TYPE:
ON-SITE DISINFECTION UNIT USED IN DRINKING
WATER TREATMENT SYSTEMS
APPLICATION:
ON-SITE DISINFECTANT GENERATION AND
INACTIVA TION OF PSEUDOMONAS
TECHNOLOGY NAME:
OXI-2B
COMPANY:
OXI COMPANY, INC.
ADDRESS:
700 ORIOLE DRIVE, UNIT 111A PHONE: (757)422-0177
VIRGINIA BEACH, VA 23451 FAX: (757) 422-9716
WEB SITE:
n/a
EMAIL:
donald.e.meyers@worldnet.att.net
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) pilot, one of 12 technology areas under ETV. The DWTS pilot recently evaluated the
performance of an on-site disinfectant generation system used in package drinking water treatment system
applications. This verification statement provides a summary of the test results for the OXI Company's
OXI-2B System. ARCADIS Geraghty & Miller, an NSF-qualified field testing organization (FTO),
performed the verification testing.
01/28/EPADW395 The accompanying notice is an integral part of this verification statement. June 2001
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ABSTRACT
Verification testing of OXI's on-site disinfectant generation system OXI-2B was conducted for 30 days
between June 26 and August 17, 2000. The OXI-2B system is capable of producing at least 1 lb of
chlorine in water using 2.7 lb of salt (NaCl) and 2.2 AC kilowatt hours (kWh) of power. In addition, the
system was capable of producing a 4.2 log kill of Pseudomonas aeruginosa bacteria when chlorine is
dosed to achieve a CT of 56 based on actual (field-confirmed) hydraulic retention time or a CT of 30
based on a T10 value in water with a pH between 7.0 and 8.0 and turbidity of 20 NTU or less, organic
carbon concentrations between 1.8 and 2.6 mg/L and an alkalinity of less than 20 mg/L as CaC03.
TECHNOLOGY DESCRIPTION
The OXI-2B disinfectant generation unit consists of two electrolytic cell halves, a brine tank and pump,
and a stand with the power supply and piping attached. The OXI-2B unit uses sodium chloride (NaCl)
brine to produce an oxidant gas, that is drawn into a side stream of the water by means of a venturi. The
key part of the unit consists of an anode and cathode compartment separated by a proprietary membrane.
When a direct current (DC) voltage is imposed across the cell, the (CI) ions are attracted to the
positively-charged anode and will combine to form chlorine (Cl2) molecules, which will initially react
with water from the brine solution. At a pH of about 2, an equilibrium is reached where free Cl2 gas is
released to the air in the upper part of the enclosed anode compartment. Gas is drawn into a side stream
of water by means of a venturi.
VERIFICATION TESTING DESCRIPTION
Test Site
The host site for this demonstration is the SJWD Water District Drinking Water Treatment Plant in
Lyman, South Carolina, which draws water from the Middle Tyger River. The water is generally of good
quality with a turbidity of less than 10 nephelometric turbidity units (NTU), hardness under 10 g/L and
TOC of approximately 2.5 mg/L. During storm events, the turbidity may rise significantly. Furthermore,
the water is known to have coliforms with counts generally varying between 100 to 1,000 colony forming
units (CFU) per 100 ml. Raw water was drawn at a rate of 23 gallons per minute (gpm) from a sump
directly in contact with the Middle Tyger River.
Methods and Procedures
The test was divided into three tasks: 1) Equipment Disinfection Production Capabilities and Operation,
2) Microbiological Contaminant Inactivation (Challenge Test), and 3) Treated Water Quality.
The objectives of Task 1 included the generation of data that describe the operation of the OXI-2B, i.e.,
the concentration of disinfectant (as chlorine) produced, the electrical power consumption per pound of
available chlorine, the sodium chloride consumption per pound of available chlorine, and the amount of
potable water used. The combined waste flow rate from anode and cathode, pH, and temperature were
recorded once per day and the waste composition was determined once during the test. The electric
power consumption of the system was also monitored. The sodium chloride consumption was determined
based on a comparison of the mass of sodium chloride added to the OXI-2B and the total disinfectant
production (as chlorine).
The objective cf this task was to verify OXI-2B's efficacy for inactivation of P. aeruginosa when
disinfectant (as chlorine) is dosed to achieve a concentration time (CT) of 70 in water with a pH between
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6.0 and 8.0 and turbidity of 20 NTU or less, organic carbon concentrations between 1.0 and 3.0 and an
alkalinity less than 20 mg/L as CaC03. This microbe was spiked into the raw water flow for a period of
time equivalent to three hydraulic retention times. Subsequent analyses revealed an average P.
aeruginosa effluent concentration of 1.5 x 104 CFUs/100 ml. P. aeruginosa enumeration of the samples
was done using Standard Methods 9213 E. Membrane Filter Technique for P. aeruginosa. During the
challenge testing, the total and free chlorine concentrations were verified. P. aeruginosa was selected as
the bacterial challenge test organism because the Pseudomonas species background in the raw water was
expected to be minimal and selective culture methods exist such that P. aeruginosa can be reproducibly
cultured in the disinfected water.
The objective of the treated water quality task was to assess the impact that treatment with disinfectant
generated by the OXI-2B has on treated water quality. Water quality parameters that were monitored
during the test period include: pH, temperature, turbidity, chlorine residual (free and total), hydrogen
sulfide, alkalinity, TDS, ammonia nitrogen, total organic carbon (TOC), ultraviolet absorbance (UVA) at
254 nanometer (nm), true color, iron, manganese, chloride, chlorite, chlorate, sodium, total coliforms, and
heterotrophic plate count (HPC) bacteria. Simulated Distribution System testing for disinfection by-
product (DBP) formation was conducted as a one-time event.
VERIFICATION OF PERFORMANCE
Operation and Maintenance
The OXI-2B system was fully automated and capable of normal operation without manual intervention.
During the ETV test the float switch in the brine tank got stuck and had to be operated manually on
occasion. Other than periodically adding salt, no maintenance was required during the test period.
However, ARCADIS found the Operation & Maintenance manual limited and suggests that OXI provides
a (ring-)bound operations and maintenance manual with the unit that makes ample use of illustrations and
schematics and includes comprehensive operational instructions.
Disinfectant Production Capabilities
The OXI-2B system produced and dosed oxidant (measured as chlorine) constantly and effectively during
the test. All chlorine analyses were done onsite in the SJWD laboratory. The average finished free and
total chlorine concentrations were 3.07 and 3.54 mg/L respectively. During the test the raw water flow
rate was maintained at the set rate of 23 gpm. The free and total chlorine content of the disinfectant
stream was 38 mg/L with a standard deviation of 9 mg/L and 42 mg/L with a standard deviation of 8
mg/L respectively. Because the total volume of the disinfectant stream was 510,407 L, the total chlorine
produced during the ETV-test was 21 kg (46 lb).
A total of 240 lb of salt was used during the test. Most salt was added during the first part of the test:
during the first 10 days, 120 lbs was added and during the last 10 days, only 40 lbs was added. The OXI-
2B system was required to have a brine overflow, which was considerable during the first part of the test
resulting in 5.2 lbs of salt expended for each pound of total chlorine produced. During the later part of
testing, the brine overflow was significantly reduced. In the last 10 days of the test, 40 lbs of salt was
needed to produce approximately 7 kg (15 lbs) of chlorine, resulting in a ratio of only 2.7 lbs salt/lb
chlorine. OXI states that the newer models of the OXI disinfectant systems do not include a brine
overflow, which they indicate was a cause of the higher salt consumption during verification testing.
01/28/EPADW395 The accompanying notice is an integral part of this verification statement. June 2001
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Microbiological Contaminant Inactivation
Based on the results of an earlier tracer test, the hydraulic retention time was calculated to be 19 minutes.
ARCADIS performed a challenge test to assess the disinfection capabilities of the OXI-2B system on P.
aeruginosa. The concentration for P. aeruginosa in the broth culture was 1.6 x 1010 CFUs/100 ml. The
results of the P. aeruginosa challenge test show that the OXI-2B system is capable of a 4.2-log kill of P.
aeruginosa at a CT value of 56 based on actual hydraulic retention time or a CT of 30 based on a T10
value.
Finished Water Quality
In-line turbidity readings were taken twice daily for finished water and were verified by taking grab
samples. The OXI-2B system has no apparent effect on turbidity: the average raw water turbidity was
11.45 NTU and the average finished water turbidity was 11.67 NTU for grab samples and 10.92 NTU for
in-line samples.
The OXI-2B has no apparent effect on UVA, tue color, TOC, manganese, and iron. Readings for
chlorite and chlorate were always below the detection limit of 20 |Jg/L. The OXI-2B system produced
some chloride (6.0 mg/L), which can probably be attributed to the use of brine. Ammonia nitrogen was
not detected in raw nor finished water.
The OXI-2B system performed well in eliminating total coliforms. For all test days, total coliforms were
reduced to zero cfu/100 ml. The OXI -2B system was very effective in reducing HPC during the first 20
days of the test, but for the remaining 10 days of the test, the HPC kill capacity diminished. Although
ARCADIS has no complete explanation for this phenomenon, the concentration of heterotrophic bacteria
in the raw water samples generally increased by an order of magnitude during this same interval.
Total trihalomethanes (TTHMs) and haloacetic acids (HAAs) were also analyzed as part of the ETV test.
None of these analytes were detected in the raw water. The OXI-2B system generated some chloroform
(10 |J,g/L) and small amounts of bromodichloromethane (2.8 |Jg/L) and dibromochloromethane (0.3
|jg/L), whereas none of the other TTHMs were detected. Average dichloroacetic acid and trichloroacetic
acid concentrations were 18 |jg/L and 21 |jg/L respectively. Small amounts of bromochloroacetic acid,
monochloroacetic acid, and bromodichloroacetic acid were detected. No other HAAs were detected.
Simulated distribution system (SDS) testing was conducted to determine the extent to which disinfection
byproducts would be formed when the OXI-2B was used as source for both primary and residual
disinfection. Testing included analyses for TTHMs and HAAs. Significant amounts of chloroform (~ 85
|jg/L), dicholoracetic acid (46-50 |Jg/L), trichloroacetic acid (78-91 |Jg/L) and relatively low levels of
bromodichloromethane (9.9-11 |_ig/L). dibromochloromethane (0.7-0.8 |_ig/L). bromochloroacetic acid
(4.1-4.2 |_ig/L). monochloroacetic acid (5.3-6.3 |_ig/L). and bromodichloroacetic acid (4.3-4.6 |_ig/L) were
found. The support system for the verification of the OXI-2B during this project was not designed to
remove dissolved organics from the raw water prior to chlorination. Thus, the formation of substantial
quantities of DBPs during the verification interval is not a surprising result.
Waste Production
The OXI-2B produced a small continuous waste stream of 13.7 ml/min (5.2 gal. or 19.8 L per day). The
waste stream had a high alkalinity, pH, and a high TDS content. The average alkalinity of the waste was
30,960 mg/L, the pH was 12.91, and the TDS was 13,800 mg/L. According to OXI documentation, the
OXI-2B cathode generates 11.2 L of hydrogen for each 35.5 gram of total chlorine. Because 21 kg total
01/28/EPADW395 The accompanying notice is an integral part of this verification statement. June 2001
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chlorine were generated, 6,625 L of hydrogen were produced over the duration of the verification test
which was vented to the atmosphere.
Original Signed by
Frank Princiotta for
E. Timothy Oppelt
07/25/01
E. Timothy Oppelt Date
Director
National Risk Management Laboratory
Office of Research and Development
United States Environmental Protection Agency
Original Signed by
Gordon Bellen
Gordon Bellen
Vice President
Federal Programs
NSF International
07/26/01
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 Inactivation of
Microbiological Contaminant dated August 1999, the Verification Statement, and the
Verification Report (NSF Report #01/28/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)
01/28/EPADW395 The accompanying notice is an integral part of this verification statement. June 2001
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May 2001
Environmental Technology Verification Report
On-Site Disinfectant Generation and
Inactivation of Pseudomonas in Raw Drinking Water
OXI Company, Inc.
OXI Generator Model 2B
Prepared for:
NSF International
Ann Arbor, Michigan 48105
Prepared by:
ARCADIS G & M
4915 Prospectus Drive, Suite F
Durham, NC 27713
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 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 the NSF International (NSF) and the United States Environmental Protection
Agency (EPA) by ARCADIS G & M (ARCADIS), in cooperation with OXI Company. The test
was conducted during June, July, and August 2000 at the SJWD Drinking Water Plant in Lyman
South Carolina.
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) has been instituted 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 are 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 package drinking water systems that serve small communities under the
Drinking Water Treatment Systems (DWTS) ETV Pilot Project. 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),
in this case ARCADIS, to conduct verification testing under the approved protocols.
The ETV DWTS is being conducted by NSF 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
Notice i
Foreword ii
Table of Contents h
Abbreviations and Acronyms v
Acknowledgements vii
Chapter 1: Introduction
1.1 ETV Purpose and Program Operation
1.2 Testing Participants and Responsibilities
1.2.1 NSF International !
1.2.2 Field Testing Organization !
1.2.3 Manufacturer :
1.2.4 Analytical Laboratories :
1.2.5 U.S. Environmental Protection Agency -
1.3 Verification Testing Site <
1.3.1 Source Water <
1.3.2 Pilot Effluent Discharge
Chapter 2: Equipment Description and Operating Processes <
Chapter 3: Methods and Procedures 1
3.1 Task 1: Equipment Disinfection Production Capabilities 1
3.2 Task 2: Microbiological Contaminant Inactivation Y.
3.2.1 Hydrodynamic Tracer Test Y.
3.2.2 Protocol for Bacterial Challenge Test li
3.3 Task 3: Treated Water Quality Y
3.4 Operation and Maintenance II
Chapter 4: Results and Discussion I1
4.1 Qualitative Operational and Maintenance Issues I1
4.2 Disinfectant Production Capabilities (Task 1) 2i
4.3 Microbiological Contaminant Inactivation (Task 2) 2<
4.4 Finished Water Quality (Task 3) 2!
4.5 Waste Producti on 3 '.
Chapter 5: Quality Assurance 3:
5.1 Calculation of DQI Goals 3:
5.2 Blanks, Duplicates and Hold Times 3'
5.3 Daily and Biweekly QA/QC Verifications 3!
5.4 Internal Audits 31
Chapter 6: References 4i
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Table of Contents, continued
Tables Page
1-1 Average Feed Water Quality During ETV Test Period 5
3-1 Sampling and Analysis Summary 12
3-2 Tracer Test Data 14
4-1 Sodium Chloride Consumption 21
4-2 Flow and Electrical Reading Summary 21
4-3 Free and Total Chlorine Concentrations 23
4-4 Bacterial Challenge Test Results 25
4-5 Results of Total and Free Chlorine Testing during Bacterial Challenge Testing 28
4-6 Summary of Daily pH, Temperature, and Turbidity Readings 28
4-7 Miscellaneous Weekly and Biweekly Data 30
4-8 Total Coliforms and Heterotrophic Plate Counts 31
4-9 TTHMs and HAAs 32
4-10 Simulated Distribution System Test Results 33
4-11 Results of Heavy Metal Analysis on Water Softener Regeneration Waste Stream 34
5-1 Data Quality Indicator Goals for Critical Measurements 35
5-2 Calculated DQIs for Critical Measurements 36
5-3 Trihalomethane Recoveries (70-130% criteria) 36
5-4 Haloacetic Acid Recoveries for 20 ng/L Standard (70-130% criteria) 37
Figures
2-1 Installation Drawing of OXI-2B 6
2-2 Front View OXI-2B 7
2-3 Rear View OXI-2B 7
2-4 OXI-2B Verification Test Flow Diagram 10
3-1 F-Curve for ClorTec T-12 ETV Tracer Test 15
4-1 Bar Graph of Bacterial Challenge Test Positive Control Samples 26
4-2 Mean Enumeration Values of Positive Control Samples 26
Appendices
A. Internal Audit Report
B. Raw Data Tracer Test
C. Daily Logbook Data Sheets
D. Analytical Data, Laboratory Results
E. OXI-2B Instruction Manual
F. B ound N oteb ook
G. Results of Raw Water Rotameter Verification
H. Some Theoretical Aspects of Electrochemical Chlorine Production
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Abbreviations and Acronyms
A amperes
AC alternating current
CT concentration time
CFU colony forming units
DBP disinfection by-product
DC direct current
DQA data quality audit
DQI data quality indicator
DWTS drinking water treatment system
ETV Environmental Technology Verification
FOD field operations document
FRP fiberglass reinforced plastic
ft feet
FTO field test organization
gpm gallons per minute
HAAs haloacetic acids
HPC heterotrophic plate count
HRT hydraulic retention time
Hz Hertz
IC ion chromatography
ICP inductively coupled plasma
kg kilogram
kWh kilowatt-hour
1 liter
lb pound
LCS laboratory control spike
LSCD laboratory control spike duplicate
mg/L milligrams per liter
ml milliliter
MS/MSD matrix spike/matrix spike duplicate
NaCl sodium chloride
NSF NSF International, formerly known as the National Sanitation Foundation
NTU nephelometric turbidity units
OIT operator interface terminal
OSHA Occupational Safety & Health Administration
pH minus log hydrogen concentration
PEA performance evaluation audit
PE(S) performance evaluation (sample)
PLC programmable logic controller
ppm parts per million
psi pounds per square inch
pt/Co referring to the ratio of platinum to cobalt in a visual color standard
QAPP quality assurance project plan
QA/QC quality assurance, quality control
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RMP
risk management plan
RMS
Root Mean Square
RPD
relative percent difference
RSD
relative standard deviation
SDS
simulated distribution system
IDS
total dissolved solids
TOC
total organic carbon
TSA
technical system audit
TTHMs
total trihalomethanes
U.S. EPA
United States Environmental Protection Agency
UVA
ultraviolet absorbance
ZCS
zero current switching
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ACKNOWLEDGMENTS
The Field Testing Organization, ARCADIS, 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.
ARCADIS G & M
4915 Prospectus Drive, Suite F, Durham, NC 27713
Contact Person: Michiel Doom
The laboratory selected for microbiological analysis and non-microbiological analytical work for
this verification project was:
Environmental Health Laboratories
110 S. Hill Street, South Bend, IN 46617
Contact Person: Paul Bowers
The Manufacturer of the Equipment was:
OXI Company, Inc.
700 Oriole Drive, Unit 111A
Virginia Beach, VA 23451
Contact Person: Don Meyers
ARCADIS wishes to thank the staff of the SJWD Drinking Water Purification Plant in Lyman,
South Carolina and Mr. Doug Waldrop for all their cooperation and practical advice received
during the test.
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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), 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. This ETV test under the
DWTS program evaluated the operation of the OXI-2B System, which is an on-site disinfectant
generation system used in drinking water treatment disinfection applications. The ETV test
evaluated the OXI-2B system's ability to produce at least 1 lb of total chlorine in water using a
maximum of 2 lb of salt (NaCl) and a maximum of 2.6 AC kilowatt hours of power. In addition,
during a challenge test, the log kill of P. aeruginosa bacteria was determined as a result of
dosing disinfectant to achieve a CT of 70.
1.2 Testing Participants and Responsibilities
The ETV testing of the OXI-2B System was a cooperative effort between the following
participants:
NSF International
ARCADIS
OXI Company, Inc.
SJWD Drinking Water Purification Plant
U.S. Environmental Protection Agency
The following is a brief description of each ETV participant and their roles and responsibilities.
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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 package drinking water treatment systems through the
EPA's ETV Program.
NSF provided technical oversight of the verification testing. An audit of the field analytical and
data gathering and recording procedures was conducted. NSF also provided review of the Field
Operations Document (FOD) and this report.
Contact Information:
NSF International
789 N. Dixboro Rd., Ann Arbor, MI 48105
Contact Person: Bruce Bartley, Project Manager
Phone: (734) 769-8010
Fax: (734) 769-0109
Email: bartley@nsf.org
1.2.2 Field Testing Organization
ARCADIS, an infrastructure and environmental engineering consulting firm, conducted the
verification testing of the OXI-2B System. ARCADIS is an NSF-qualified Field Testing
Organization (FTO) for the ETV DWTS pilot project.
The FTO was responsible for conducting the verification testing for 30 calendar days. The FTO
provided all needed logistical support, established a communications network, and scheduled and
coordinated activities of all participants. The FTO was responsible for ensuring 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 pilot 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.
FTO employees conducted the onsite analyses and data recording during the testing. Oversight
of the daily tests was provided by the FTO's Project Manager.
Contact Information:
ARCADIS G & M
4915 Prospectus Drive, Suite F, Durham, NC 27713
Contact Person: Michiel Doom
Phone: (919) 544-4535
Fax: (919) 544-5690
Email: mdoorn@arcadis-us.com
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1.2.3 Manufacturer
The treatment system is manufactured by OXI Company, Inc., manufacturer of on-site
disinfectant generation systems for the drinking water industry.
The manufacturer was responsible for supplying a field-ready OXI Generator Model 2-B
equipped with all necessary components including treatment equipment, instrumentation and
controls and an operations and maintenance manual. The manufacturer was responsible for
providing logistical and technical support as needed, as well as providing technical assistance to
the FTO during operation and monitoring of the equipment undergoing field verification testing.
Contact Information:
OXI Company, Inc.
700 Oriole Drive, Unit 111A, Virginia Beach, VA 23451
Contact Person: Don Meyers
Phone: (757)422-0177
Fax: (757)422-9716
Email: donald.e.meyers@worldnet.att.net
1.2.4 Analytical Laboratories
Chlorine residual, pH, turbidity, alkalinity, hydrogen sulfide analyses, as well as Coliforms and
HPC counts were conducted on-site in the laboratory of the SJWD drinking water plant:
SJWD Water District
161 Groce Road, Lyman, SC 29365
Contact Person: Mr. Doug Waldrop
Phone: (864) 949-2520
The SJWD on-site laboratory is certified by the state of South Carolina to perform selected
drinking water analyses (Certificate No. 42012001).
Off-site analyses including Pseudomonas aeruginosa, were performed by:
Environmental Health Laboratories
110 Hill St., South Bend, IN 46617
Contact Person: Paul Bowers
Phone: (219)233-4777
Fax: (219)233-8207
EHL has been issued a certificate by the State of South Carolina to perform selected drinking
water analyses (Certification No. 95005001).
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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. This verification effort
was supported by Drinking Water Treatment Systems Pilot operating under the ETV Program.
This document has been peer reviewed and reviewed by NSF and EPA and recommended for
public release.
1.3 Verification Testing Site
The host site for this demonstration is the SJWD Water District Drinking Water Treatment Plant
in Lyman, South Carolina. The SJWD Water District Drinking Water Treatment Plant draws
water from the Middle Tyger River. The Middle Tyger River is identified as watershed
03050107-040 and is located in Greenville and Spartanburg Counties. The watershed occupies
64,948 acres of the Piedmont region of South Carolina. Land use/land cover in the watershed
includes: 9.02 percent urban land, 23.85 percent agricultural land, 0.77 percent scrub/shrub land,
1.08 percent barren land, 64.32 percent forested land, and 0.95 percent water. There are several
ponds and lakes (16-500 acres) in this watershed used for recreation, industrial, municipal and
irrigation purposes. There are a total of 120.3 stream miles in the Middle Tyger River.
At the SJWD Drinking Water Treatment Plant, Middle Tyger River water is withdrawn into a
flash mixer where caustic, alum and free chlorine are added. Next the water moves through 4-
stage flocculators and into sedimentation basins. Following the sedimentation basins, the water
being processed goes through dual media sand/anthracite filters into a clear well where addition
of caustic, phosphate, and occasionally free chlorine takes place. The clear well effluent goes
into a storage reservoir prior to being distributed to the public. The SJWD plant has a capacity
of 6 million gallons per day (mgd).
1.3.1 Source Water
Water for the verification test at the SJWD plant is raw water, drawn directly from the Middle
Tyger River. Upstream of the plant is a reservoir that is used to regulate water levels in the river.
During times of draught, the reservoir levels may fall significantly and in extreme cases the
water may have high amounts of manganese and cadmium in it, which had been stored in the
reservoir sediments. During storm events, the turbidity of the water goes up significantly.
Typically, the turbidity is around 10 NTU or lower. A summary of average feed water quality is
presented in Table 1-1 below.
Aquatic life uses are fully supported upstream based on the macroinvertebrate community, but
may be threatened by a significantly increasing trend in turbidity, occurrences of zinc, and a very
high concentration of cadmium measured in sediment. Aquatic life uses are fully supported
midstream but may be threatened by a significantly decreasing trend in pH. Aquatic life uses are
fully supported downstream based on physical, chemical and macroinvertebrate community data.
Recreational uses are not supported at any site due to fecal coliform bacteria excursions and
there is a significantly increasing trend in fecal coliform bacteria concentration.
4
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Table 1-1. Average Feed Water Quality During ETV Test Period
Unit
Average
Standard
Deviation
Minimum Maximum
95% Conf.
Interval,
Min
95% Conf.
Interval,
Max
Chlorine, Free
mg/L
0.02
0.02
<0.01
0.10
0.01
0.02
Chlorine, Total
mg/L
0.03
0.02
<0.01
0.15
0.03
0.04
pH
7.20
0.12
6.97
7.98
7.15
7.24
Temperature
C
24.6
1.2
22.0
26.5
24.2
25.1
Turb (grab)
NTU
11.45
16.85
5.16
90.40
5.42
17.48
Total Coliforms
#/100 ml
532
381
0
1400
372
691
HPC
#/ml
892
1254
98
>5200
356
1428
H2S
mg/L
<2
0
<2
<2
n/a
n/a
Alkalinity
mg/L
19
0.9
18
20
18
20
TDS
mg/L
68
n/a
60
76
n/a
n/a
UVA (UV 254)
1/cm
0.19
0.06
0.14
0.27
0.13
0.25
True Color
Pt/Co u.
65
24
50
100
42
88
Ammonia Nitrogen
mg/L
<0.3
0
<0.3
<0.3
n/a
n/a
TOC
mg/L
2.2
0.5
1.8
2.6
1.7
2.7
Chloride
mg/L
2.4
0.2
2.2
2.6
2.2
2.5
Chlorate
pg/L
<20
0
<20
<20
n/a
n/a
Chlorite
pg/L
<20
0
<20
<20
n/a
n/a
Manganese
pg/L
145
n/a
120
170
n/a
n/a
Iron
pg/L
1.7
n/a
1.4
2.0
n/a
n/a
Sodium
mg/L
15.2
n/a
3.3
27
n/a
n/a
n/a = Not applicable, because the sample size is too small, or values are below detection limit.
1.3.2 Pilot Effluent Discharge
The effluent of the pilot treatment unit was disposed through a two-inch pipe to a nearby man
hole, that ultimately drained into the alum sludge holding pond of the plant. Because the effluent
did not leave the jurisdiction of the SJWD plant, no discharge permit was required.
5
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Chapter 2
Equipment Description and Operating Processes
The disinfectant generation unit supplied by OXI Co. for the verification program is the OXI-2B.
The OXI system consists of two cell halves bolted together for shipment, a brine tank and pump,
a stand with the power supply and piping attached, and a box of accessories. The cell is poly
vinyl chloride (PVC) and is strapped to the pallet for shipping. The power supply is in a
fiberglass enclosure mounted to an aluminum stand which is in turn mounted to the pallet. The
brine pump is also mounted to the pallet and the plastic brine tank sits on the pallet. Where
possible, all components are plastic.
The OXI-2B unit uses sodium chloride (NaCl) brine to produce oxidant gas. Because the gas can
not be quantified directly, it is measured as free and/or total chlorine after it has been dissolved
in water. According to the manufacturer and White (1992), the gas consists of chlorine and
short-lived oxygen radicals. This gas is drawn into a side stream of the water by means of a
venturi. Figure 2-1 is a simplified installation drawing provided by OXI and Figures 2-2 and 2-3
display the front and back of the unit.
Oxi
Oxidant Generator
Automsflc Model
Intel FIHsr
(«U m»jh «s»»ri}
Minimum Caustic Lew]
Install Bolls lo Sacure —
Towntf to Base (0)
Qutl« lo Wntsr
Storage tank ™
InlBctor
ln|Bctof Tube —
W«t*r lni«t
Tcwtr
j Plow Control Vat»«
Automatic Wtlsr
Additon Vdfces
Minimum Br™
Anode end Cathode
Cunvmimsrit Drain Una
Overflow
to Diet
Fu3S
QiVOO
SvjBcti
Shown wMl lower (nxitwar raamwod.
' Pvmt Supply
Installation Drawing
Figure 2-1 Installation Drawing of OXI-2B
6
-------
Figure 2-2: Front View 0XI-2B Figure 2-3: Rear View 0XI-2B
The key part of the unit consists of an anode and cathode compartment separated by a proprietary
membrane. The membrane will allow positively-charged ions to pass through but will block
negatively-charged ions. When NaCl is dissolved in water it ionizes to (CI) and (Na+) ions and
when a direct current (DC) voltage is imposed across the cell, the positively-charged ions (Na+)
are attracted to the negatively-charged cathode and pass through the membrane. The (CI) ions
are attracted to the positively-charged anode and stay in the anode compartment. Since an
electrolyte is initially electrically neutral, an imbalance is created because the positive ions have
passed through the membrane leaving the negatively-charged (CI) ions without a neutralizing
positive charge. To compensate for this, (CI) ions combine to form Ct molecules thereby
releasing two electrons. The chlorine initially reacts with water, thereby creating hypochlorite
and hydrochloric acid which will lower the pH in the anode compartment.
7
-------
Reactions at anode:
2 CI" -» Cl2 + 2 e"
Cl2 + 2H20 <-> HO CI + HC1
(1)
(2)
At a pH of about 2, an equilibrium is reached where free Ct gas does not react with water any
more and is released to the air in the upper part of the anode compartment, where it reportedly
reacts with air to form various oxidants (White, 1992). Next, the oxidant gas is drawn into the
stream of water by means of a venturi. According to the manufacturer, the oxidant gas quickly
forms products comparable to those from standard chlorine/hypochlorite dosage in water and
these compounds can, therefore, be quantified as free or total chlorine. Gas speciation before the
gas enters the water was beyond the scope of this field test.
At the cathode, sodium (Na+) ions combine with OH ions to form NAOH (sodium hydroxide).
The cathode side of the OXI unit produces 1.1 g of sodium hydroxide for each g of chlorine
produced. A timer is factory preset to periodically add water to the cathode compartment
keeping the sodium hydroxide concentration in the 5% - 10% range. During this water addition
cycle, the diluted sodium hydroxide overflows into the drain manifold on the rear of the stand
where it mixes with the (slightly) acidic overflow from the anode compartment. The result is a
high pH solution with a total dissolved solids (TDS) content of about 120 mg/L that is be piped
to a drain or waste collector.
Reactions at cathode:
On a direct molar basis the cathode generates 11.2 liters of hydrogen for each 35.5 gram (g) of
chlorine. A fitting and a tube on the cathode compartment lid are used to vent this small amount
of hydrogen produced to a safe distance away from the generator.
In order to have sufficient salt to sustain operation it is necessary to continually flow brine
through the anode compartment. Brine is continually pumped into the anode compartment by a
diaphragm pump with an adjustable stroke, causing a slight overflow. This overflow enters the
drain manifold on the rear of the stand, where it mixes with the sodium hydroxide from the
cathode compartment.
The brine tank holds a large reserve of salt and brine, as well as a sequestering agent. A
sequestering agent is used to inhibit chemical precipitation of calcium carbonate to avoid
clogging the OXI membrane. The OXI sequestering agent is a proprietary product developed by
the Mayo Chemical Company specifically for OXI. Salt must be added manually to the brine
tank about every 15 days of actual operation. The brine tank is fed by a tap water hose and has a
floater valve that controls the tap water supply.
The system operates in automatic mode, with the oxidant gas being injected (drawn) under a
slight vacuum into a side stream of raw water. The side stream is then mixed with the main raw
water flow. The combined low then enters a contactor consisting of two baffled, 200-gallon
2 H20 + 2 e" -» H2T + 2 OH"
Na+ + OH" -> NaOH
(3)
(4)
8
-------
tanks in series to establish a minimum CT of 70. Finally the flow is discharged in the alum
settling sludge holding pond.
The OXI system power supply uses a Zero Current Switching (ZCS) technology to convert 115
or 220 volt AC to 10 volt DC. ZCS offers reliable high power density with fast response, very
low conducted and radiated noise, and requires minimal cooling. The advantages of using this
technology as a DC supply for the OXI electrolytic cell are a significantly lower AC power
requirement with less heat generation in the cell and the ability to mount the power supply
components in a gas-tight box so that all power supply components are completely protected
from corrosion. The control system for the OXI unit is preset at the factory on the internal
control boards of the unit. Manual control of the current for the unit is performed at the door
panel. Once adjusted, this amperage will be maintained until manually changed. The rate of
oxidant generation can be manually controlled by the operator or automatically controlled by a
chlorine residual or oxidation reduction potential controller.
To test the OXI-2B system without interfering with the existing operations of the SJWD facility,
a parallel treatment system was established for the purposes of this verification program. The
system begins with a pump that draws from an existing intake sump on the Middle Tyger River.
This pump has a capacity larger than that needed for this demonstration and a throttling valve to
regulate the flow to 23 gpm. A side stream of the raw water was established that served to inject
the oxidant gas. This side stream is equipped with a rotometer, as is the main raw water stream.
The water with disinfectant passes through two retention tanks of 795 liters each to reach the
required retention time of 19 minutes. Chapter 3 includes a summary and results of a tracer test
that was conducted to determine the hydraulic retention time of the pilot system. The
verification system flow diagram is shown in Figure 2-4.
Under normal circumstances, for example in the disinfection of partially treated water, the OXI-
2B does not require potable water to be consumed during treatment. However, at SJWD the
OXI-2B was tested on raw water to provide a challenging environment. As a precautionary
measure to prevent possible damage to the system, potable water was used to make brine.
Before sampling, the disinfectant stream was flushed out with potable water for a few minutes,
after which the chlorine samples were taken of the disinfectant dispersed in the potable water
flow. This was done for sampling purposes only, because the components of the raw water
would have interfered with the analysis. After sampling was completed, the original raw water
flow through the disinfectant stream was established again.
9
-------
230 VAC, 10
115 VAC, 10
Sodjum waste
To Alum Slojidge
Disposal Pijmd
Potable water
Hook-up
\
CN
Backflow
\ Prevention and
\ Throttling Valve
Centrifugal
Pump
115 VAC, 10
M.O. water
sampling port
Baffled 200-Gallon Tanks
Rotometer
Treated water
sampling port
1X3
Injection port
I
T
X Raw water
sampling port
rinJ
0
Finished water
sampling
¦tx]
-------
Chapter 3
Methods and Procedures
The test was divided into three tasks, which are detailed below:
1. Equipment Disinfection Production Capabilities
2. Microbiological Contaminant Inactivation (Challenge test), and
3. Treated Water Quality
In addition, operation and maintenance aspects that arose during the test were evaluated during
the ETV test period. Table 3-1 includes a sampling and analysis summary for parameters
monitored under the three tasks. Also included is the sampling frequency, analytical method,
analytical laboratory, reporting limit, hold time and the type of container/preservative that was
used.
3.1 Task 1: Equipment Disinfection Production Capabilities
The objectives of Task 1 included the generation of data that describe the operation of the OXI-
2B. The operation of the OXI-2B was verified in terms of:
a) the concentration of disinfectant (as chlorine) produced,
b) the electrical power consumption per pound of available chlorine,
c) the sodium chloride consumption per pound of available chlorine, and
d) the amount of potable water used.
The raw water flow rate was recorded twice daily. These recorded flow measurements were
used to calculate the total number of gallons that the OXI-2B treated during the verification
program. The total generated volume and concentration of disinfectant (as chlorine) was
determined and recorded. This was done by determining the volume of the side stream
(Disinfectant Stream) into which the oxidant gas was dispersed, and the concentration of
disinfectant (as free and total chlorine in mg/L in water).
The electric power consumption of the system was monitored. The control panel of the OXI-2B
has readouts for current and voltage at the cell, which were recorded once per day. The totalized
AC power consumption going to the cell was also to be monitored. However, during the test it
was noticed that this power meter was not functioning properly and voltage and current readings
with a hand-held multi-meter were taken instead. Total power required for a given period of
time in kWh was calculated and this number was compared with disinfectant concentration (as
free and total chlorine) and volume consumption data to determine the amount of electricity
required to produce a pound of available chlorine. The sodium chloride consumption was
determined based on a comparison of the mass of sodium chloride added to the OXI-2B and the
total disinfectant production (as chlorine). The data generated from tracking the consumption of
these raw materials were used to verify operational performance of the OXI unit.
11
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Table 3-1. Sampling and Analysis Summary
Parameter
Sampling
Test Stream
Analytical
Analytical
Reporting
Hold Time
Container/
Frequency
Method
Laboratory
Limit
Preservative
pH
1/Day
Raw, Treated (first tank),
Finished, Waste
4500 H
SJWD
n/a'
Analyze
Immediately
Temperature
1/Day
Raw, Finished, Waste
2550 B
SJWD
n/a
Analyze
Immediately
Raw Water Turbidity
1/Day
Raw water
2130 B
SJWD
0.1 NTU
48 hours
Finished Water
In-line
Finished water
Hach1720D
SJWD
0-100NTU
n/a
n/a
Turbidity
Chlorine Residual
2/Day
Raw, Disinfectant, Finished,
Waste. (Weekly for potable
water)
4500-CI F
SJWD
0.05 mg/L
Analyze
Immediately
250-ml poly
Hydrogen Sulfide
1/Week
Raw water
SM 4500-S2-A4C
SJWD
0.1 mg/L
Not specified
100-ml glass
Alkalinity
TDS
1/Week
2/Verification Test
Raw, Finished, Waste
Raw, Finished, Waste
Total Coliform
Bacteria
5/Week
Raw,
Finished
HPC Bacteria
5/Week
Raw,
Finished
Ammonia Nitrogen
1/Week
Raw,
Finished
TOC
4/Verification Test
Raw,
Finished
UVA
1/Week
Raw,
Finished
True Color
Iron
1/Week
2/Verification Test
Raw,
Raw,
Finished
Finished
Manganese
2/Verification Test
Raw,
Finished
Chloride
Chlorite, Chlorate
1/Week
1/Week
Raw,
Raw,
Finished
Finished
Sodium
Heavy metals scan
TTHMs
HAAs
2/Verification Test
1/Verification Test
3/Verification Test
2/Verification Test
Raw, Finished
Waste
Raw, Finished
Raw, Finished
P. aeruginosa
Enumeration
25/Bacterial
Challenge Test
1/Day Raw, Balance
Finished and Controls
2320 B
2540 C
9221 B
9215 B
SJWD
SJWD
SJWD
SJWD
10 mg/L
5 mg/L
2 MPN/100
ml
14 days
7 days
24 hours
°C
°C
1000 CFU/L 8 hours
4 drops zinc
acetate
250-ml poly/4'
250-ml poly/4'
Sterile, 100-ml
poly/4 °C
0.008% Na2S203
Sterile, 100-ml
poly/4 °C
0.008% Na2S203
4500- NH 3 G
Env. Health
0.03 mg/L
28 days
100-ml poly/4 °C
Labs (EHL)
pH<2 W/ H2SO4
5310 C
EHL
1 mg/L
28 days
Glass/4 C
5910 B
EHL
0.01 cm"1
Not to
Glass/4 C
exceed 48
hrs
2120 B
EHL
5 PCU
48 hours
250-ml poly/4 °C
200.7
EHL
50 (jg/L
Analyze
250-ml poly/4 °C
Immediately
2 ml HCL/100 ml
200.7
EHL
10 (jg/L
6 months
120 plastic,
HNO3 <2
300.0
EHL
1 mg/L
28 days
100-ml poly
300.0 B
EHL
20 (jg/L
14 days, 28
120 plastics bottles
days
Chlorite EDA
200.7
EHL
500 (xg/ml
24 hours
Acid washed/4 C
200.8
EHL
varies
varies
524.2
EHL
1 (jg/L
14 days
3- 40 VOA vials
552.1
EHL
1 (jg/L
14 days
3- 40 VOA vials
See Challenge
10/100 ml
24 hours
Autoclaved 1 liter
Test Protocol
EHL
glass
n/a- not applicable
12
-------
The waste flow rate from the OXI system was recorded once per day as was the pH and
temperature of the waste stream. The waste composition was determined once during the 30-day
test and analytes included sodium, alkalinity, free and total chlorine, TDS, and NaOH, as well as
antimony, arsenic, beryllium, cadmium, chromium, copper, lead, mercury, nickel, selenium,
silver, and zinc.
During the verification interval, the OXI-2B was visually inspected by SJWD operators or
ARCADIS staff once per 8-hour shift. These visits were documented on daily logbook data
sheets (see Appendix A) and any additional comments were entered in a bound logbook
(Appendix B). The logbook was also used by SJWD operators during daily documentation of
qualitative equipment performance. Daily instrument calibrations and checks included
calibrations regarding the pH meter, thermometer, in-line turbidimeter, bench-top turbidimeter,
and the flow meter. As part of the test, operation and maintenance issues were also evaluated.
This subtask was very limited because the OXI-2B and all its parts operate automatically. Also,
no maintenance was required during the test period, with the exception of occasionally adding
salt. However, ARCADIS did report on the effectiveness of the Operation & Maintenance
manual whenever the operational progress required use of this manual.
3.2 Task 2: Microbiological Contaminant Inactivation
The objective of this task was to verify OXI-2B's efficacy for inactivation of P. aeruginosa
when disinfectant (as chlorine) is dosed to achieve a concentration time (CT) of 70 in water with
a pH between 6.0 and 8.0 and turbidity of 20 NTU or less, organic carbon concentrations
between 1.0 and 3.0 and an alkalinity less than 20 mg/L as CaCC>3. P. aeruginosa was selected
by ARCADIS as the bacterial challenge test organism because the Pseudomonas species
background in the raw water was expected to be minimal and selective culture methods exist
such that P. aeruginosa can be reproducibly cultured in the disinfected water. The laboratory
that supplied the P. aeruginosa downstream enumeration was EHL.
3.2.1 Hydrodynanric Tracer Test
The OXI-2B set-up was similar to that of another ETV test that was performed in early spring
2000. The tracer test results from this earlier test (ClorTec T-12 ETV test report, NSF
01/21/EPADW395) are included below and the results were adjusted for the OXI-2B scheme.
The only difference between the ClorTec T-12 system and the OXI system was that the OXI
system utilized two disinfectant contact tanks while the ClorTec T-12 system used four.
The tracer test was performed on March 18, 2000 to provide a profile of the tracer concentration
through the disinfection equipment as a function of time. The compound chosen to serve as the
tracer was potassium chloride (KC1). In preparation for the tracer test, raw water background
concentrations of potassium were determined. The concentrated KC1 solution was added
continuously through a dosing port for 190 minutes.
Chlorine contact chamber effluent samples were taken at 10-minute intervals throughout the 190-
minute tracer test, with the first sample taken at 10 minutes after testing began. The target
potassium concentration in the feed water to the unit (at 23 gpm) was 30 mg/L, which is greater
13
-------
than 10 times the background concentration, measured to be 2.6 mg/L during the test (note that
the 10-minute effluent sample yielded a potassium concentration of only 1.5 mg/L, implying that
the actual feed water background potassium concentration is variable and often less than the 2.6
mg/L measured on the referenced grab sample). Grab samples of the feed background, stock
solution and effluent (at 10-minute intervals) were sent to Savannah Laboratories for analysis.
The raw data results are included in Appendix B and summarized in Table 3-2.
TABLE 3-2. TRACER TEST DATA
Time (min) Total K (mg/L) F (%)
0
0
0.0%
10
1.5
5.2%
20
3.9
13.4%
30
11
37.9%
40
21
72.4%
50
24
82.8%
60
27
93.1%
70
29
100.0%
80
29
100.0%
90
29
100.0%
100
28
96.6%
110
28
96.6%
120
28
96.6%
130
28
96.6%
140
29
100.0%
150
28
96.6%
160
30
103.4%
170
29
100.0%
180
30
103.4%
190
27
93.1%
The results were plotted in an F-curve, as described in many chemical engineering and reactor
analysis texts (Levenspiel, 1972) and shown as Figure 3-1. The F-curve shows the percentage of
tracer recovered at discrete points in time (i.e., not cumulative) in the effluent versus time after
starting the continuous tracer feed. The actual hydraulic retention time was calculated as the area
above the curve, per the equation below (DiGiano, Weber, 1996).
CO
HRT=t. =jl-dF(f)
0
The F-curve was plotted on grid paper with a relatively fine grid resolution and the number of
grid squares above the curve (up to 100% recovery) were manually counted. The hydraulic
residence time (HRT) was then calculated per the equation below.
HRT = 213squares x ^ x ^rnm • _ 34 ^
grid grid
14
-------
ClorTec T-12 ETV Tracer Test Data
s
s
s
/
^1
/
Area above
Curve -
/
34.1 minutes
r
/
/
t
i
/
/
J
f
f
/
/
/
f
-I
T10 = ~18 min
*
>
MM
I
0 20 40 60 80 100 120 140 160 180 200
Time (minutes after start)
Figure 3-1. F-Curve for ClorTec T-12 ETV Tracer Test.
The chlorine contact chamber (CCC) for this system had a nominal capacity of 750 gallons.
However, because of the location of the effluent overflow pipe and the head loss induced by
piping between the three tanks employed, the actual volume of water contained in the CCC was
approximately 850 gallons. At a volumetric capacity of 850 gallons and a measured flow rate of
23 gpm (87 1/min), the theoretical HRT for the CCC for the ClorTec T-12 system was 37
minutes. The actual experimentally measured HRT of 34.1 minutes indicates that while there
was some short-circuiting, as expected, the overall performance of the experimental CCC was
quite good (within 10% of theoretical).
Per EPA Guidelines (USEPA, 1989) for calculation of CT values, the Tio value was also
determined graphically, as shown in Figure 3-1 above. Ti0 represents the elapsed time at which
the tracer concentration in the effluent is equal to 10% of the feed. As shown, the Tio for the
ClorTec system was determined to be approximately 18 minutes.
As mentioned, the only difference between the ClorTec T-12 system and the OXI-2B system is
that the OXI system utilized two disinfectant contact tanks while the ClorTec T-12 system used
four. Given this, considering that all of the contact tanks were of equal volume, and because the
system volume from disinfectant injection point to the first tank was negligible in comparison to
the contact chamber volumes, the HRTs (both theoretical and measured) and To values for the
OXI system are one-half those for the ClorTec test system. As such, the theoretical HRT is 37 /
2 or 18.5 minutes, the measured HRT is 34.1/2 or about 17.1 minutes and the Tio value is 18/2
15
-------
or approximately 9 minutes. The theoretical HRT for the section of the system to the sampling
port after the first tank can be calculated as 850 L / 87 liters per minute, or about 10 minutes.
3.2.2 Protocolfor Bacterial Challenge Test
The protocol for the bacterial challenge is sequentially outlined below.
1) The broth was subsampled at the beginning of the challenge test to create a trip control that
remained on ice during the bacterial challenge-testing interval and was shipped to the
analytical laboratory with the samples. Disinfectant flow to the system was discontinued and
a peristaltic pump and tubing was used to inject P. aeruginosa into the raw water line at a
rate intended to maximize the P. aeruginosa concentration in the raw water while assuring
that the volume of growth broth would not expire before the scheduled completion of the test.
P. aeruginosa was spiked into the raw water flow for a period of time equivalent to three
hydraulic retention times at 23-gallons/minute raw water flow (60 minutes). At the end of 60
minutes, ARCADIS collected three positive control samples, with the last sample being
collected in duplicate (XPC-60, XPC-70, XPC-80A, and XPC-80B) with 10 minutes of
elapsed time between sample collections.
2) After the collection of duplicate positive control samples at 80 minutes of elapsed time,
ARCADIS began adding disinfectant from the OXI-2B into the system with the OXI-2B
control settings being consistent with those previously used during the verification interval.
After the elapse of 3 additional HRTs (60 more minutes for a total elapsed time of 140
minutes) ARCADIS collected three sets of three treated samples each at 140 minutes, 150
minutes and 160 minutes of elapsed time. The first set of samples was collected immediately
after injection of P. aeruginosa and OXI-2B oxidant, prior to entry into Contact Tank 1. The
second set of treated samples was collected at the effluent from Contact Tank 1. The third
set of samples was collected at the effluent of Contact Tank 2. These samples were collected
with 10 minutes of elapsed time between them such that the test concluded after the elapse of
160 total minutes. One sample at the effluent of Contact Tank 2 at 160 minutes of elapsed
time was collected and analyzed in duplicate.
3) The broth was subsampled at the end of the challenge test to create a trip control that
remained on ice during the bacterial challenge-testing interval and was shipped to the
analytical laboratory with the samples. Following collection, the samples were shipped via
overnight delivery to EHL's laboratory for P. aeruginosa enumeration using Standard
Methods 9213 E. Membrane Filter Technique fori5, aeruginosa.
During the challenge testing, the raw water flow rate was periodically verified at the rotometer.
In addition, total and free chlorine concentrations were verified in the treated water from Contact
Tank 1 and the finished water from Contact Tank 2 prior to and after the completion of the
challenge test. Samples for the analysis of P. aeruginosa were collected in sterile, 1-liter sample
bottles provided by EHL. Immediately after collection, one milliliter (ml) of a dechlorinating
solution (sterile sodium thiosulfate solution 30 g/L per Standard Methods 9060 A. 2.
Dechlorination) was added as a reducing agent to prevent prolonged exposure of the P.
aeruginosa to the effects of residual chlorine. Samples were refrigerated at 4°C immediately
after collection and shipped in a cooler maintained at or below that temperature during shipment.
16
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3.3 Task 3: Treated Water Quality
The objective of this task was to assess the impact that treatment with disinfectant generated by
the OXI-2B has on treated water quality.
Water quality parameters that were monitored during the test period include: pH, temperature,
turbidity, chlorine residual (free and total), hydrogen sulfide, alkalinity, TDS, ammonia nitrogen,
total organic carbon (TOC), ultraviolet absorbance (UVA) at 254 nanometer (nm), true color,
iron, manganese, chloride, chlorite, chlorate, sodium, total coliforms, and heterotrophic plate
count (HPC) bacteria. Table 3-1 includes the treated water quality sample analyses (denoted as
"finished" water), the frequency with which individual analyses were performed, the analytical
methodologies that were followed, the laboratory performing the analyses, the reporting limits,
holding times and sampling containers that were required. Samples were preserved, stored,
shipped and analyzed in accordance with appropriate procedures and hold times, as specified by
the analytical methods.
Analytical samples were collected from various locations within the overall treatment system. A
side stream of treated water was directed to a Hach Model 1720D in-line turbidimeter. Readings
were taken twice per day. With the exception of the in-line turbidimeter, grab samples were
collected to satisfy analytical needs. When collecting a grab sample from a sample tap, sample
collection consisted of running a slow, steady stream from the sample tap, triple rinsing a
dedicated sample beaker or sample container in this stream, and allowing the intended sample to
flow down the side of the beaker or sample container to minimize bubble entrainment. When
dipping a grab sample from a particular contact tank, sample collection consisted of triple rinsing
a dedicated sample beaker with the tank water and then dipping the required sample.
Samples analyzed at SJWD included free and total chlorine, pH, temperature, bench-top
turbidity, hydrogen sulfide (H2S), alkalinity, TDS, total coliform and HPC. Also, some iron and
manganese analyses were conducted at the plant. The free and total chlorine analysis was done
at the SJWD plant laboratory immediately after sampling. The oxidant produced by the OXI-2B
is a gas and its disinfectant capabilities are measured as free and total chlorine in water. If this
had been done in raw water, uncertainties would have been introduced, because of unpredictable
constituents in the raw water that would react with the disinfectant products. Therefore, prior to
sampling, the raw water supply was directed away from the oxidant aspiration line to be replaced
by SJWD potable water. Once the potable water flow had stabilized, samples of the aspirated
oxidant (as free and total chlorine) were collected. The potable water layout is included in
Figure 2-4. After sampling, the flow was switched back to raw water.
Simulated Distribution System testing for disinfection by-product (DBP) formation was
conducted as a one-time event. Six raw water samples were collected in one-liter amber bottles
with Teflon-lined caps. The samples were pH adjusted to 8.0 ± 0.2 using 1M hydrochloric acid
(HC1) dosed with 0.8 ±0.1 percent disinfectant solution to yield a target chlorine residual of 1.0
± 0.4 mg/L after storage. The samples were capped with zero headspace and stored for 24 hours
in the dark at 20 ±1 °C. Following incubation, the six samples were reanalyzed for chlorine
residual. The sample with chlorine residuals closest to the 1.0 ± 0.4 mg/L target was submitted
for DBP testing.
17
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3.4 Operation and Maintenance
As part of the test, operation and maintenance issues were evaluated. This subtask was very
limited because the OXI-2B and all its parts operate automatically. Also, no maintenance was
required during the test period, with the exception of occasionally adding salt. ARCADIS did
report on the effectiveness of the Operation & Maintenance manual (Appendix E) when there
was a need to consult it. Comments regarding operation and maintenance were recorded in the
on-site logbook (Appendix F).
18
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Chapter 4
Results and Discussion
The OXI-2B unit was brought on site in early May, 2000. Due to construction at the SJWD
plant, however, installation and start-up was not completed until the end of June. Other
equipment, including pump, sample ports and contact tanks, had been assembled in March 2000,
prior to the OXI ETV test. The system was operated for a total of 725 hours for the during the
30-day test. The logbook notes and performance data sheets are included in Appendix C, D, and
F. Initial test runs took place on June 23 and 24, and the actual ETV verification test started on
June 26, 2000. The actual verification period lasted 30 days, but the system was shut down on
July 13 due to construction activites at the host site. On July 31, the OXI was powered up again
and the ETV test was completed. The last day of daily sampling was August 12. On August 8, a
simulated distribution system test was performed.
The microbial challenge test was performed on August 16, 2000. Ms. Tina Beaugrand of NSF
performed an audit during which the concentration of the Ps. aeruginosa broth, pump flow rate,
and sampling procedures were checked. In the audit report it was further noted that no
deviations were found from the submitted FOD during this challenge. The audit report is
included in Appendix A.
4.1 Qualitative Operational and Maintenance Issues
The OXI-2B system was fully automated and capable of normal operation without manual
intervention. ARCADIS found that there were two qualitative operational issues associated with
the OXI-2B unit: the power supply unit and the float switch in the brine tank. During
installation and initial test runs it was found that the power supply unit on the OXI had a defect.
The power supply unit was returned and the manufacturer, Xantrex, provided a temporary unit
(loaner unit). This loaner unit, however, had a lower humidity rating than the standard unit that
OXI provides. When the OXI-2B was started up on July 28, after the down period, the power
unit (loaner) tripped the breaker and the system could not be started. In discussion with OXI
Company, it was determined that this was most likely caused by humidity in the power unit. The
original power supply unit that had been repaired by Xantrex was shipped back to SJWD and
was installed back on the OXI to replace the loaner unit. This installation was simple and lasted
about 30 minutes. Once the right power unit was installed, the OXI system started up and
operated without power-related problems. It should be emphasized that the standard power unit
failed before the ETV test had started so further discussion of this failure is not considerd to be
part of the ETV test.
During the ETV test, the float switch in the brine tank did not operate well, because it got
repeatedly stuck in the off position1. Therefore, this valve was manually operated for the first
part of the test. ARCADIS installed a pressure-reducing valve in the potable water line to the
brine tank, which had a positive effect on the float valve operation. It did not get stuck anymore,
but it continued to "chatter" on occasion, indicating it still did not move completely unhampered.
The ARCADIS team further noticed that in the beginning of the test this brine overflow was
1 According to the manufacturer it is likely that problems with the brine tank float switch were caused because the unit
was not completely level.
19
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considerable and proceeded to decrease the output of the brine pump several times until the
overflow was significantly less. This had obvious consequences for the salt and the potable
water intake which will be discussed in Section 4.1.3.
Non-OXI-specific maintenance consisted of replacing a burst potable water hose, cleaning of the
rotometers, main valve and water intake, and cleaning and recalibrating the in-line turbidimeter.
OXI-specific maintenance consisted of periodically adding sodium chloride to the brine tank and
cleaning a small wire mesh filter in the water line leading to the brine tank. Because potable
water was used for making brine during the ETV test, this filter did not accumulate any debris.
However, on one occasion it was inspected because ARCADIS believed that air or debris had
accumulated in it. This turned out to be air. The inspection and cleaning procedure lasted about
five minutes.
It should be noted that the ARCADIS team spent considerable time during the first two days of
the ETV test fine tuning the system, i.e. finding the right electrical current setting to produce the
required oxidant output. ARCADIS personnel referred to the OXI manual several times during
the fine tuning of the system, but found only generic information that described the linear
relationship between current and output. ARCADIS suggests that OXI assures adequate OXI
operator assistance during start-up and also provides instructions in the Instruction Manual (see
Appendix E).
It was noted that the OXI-2B Instruction Manual had adequate installation instructions,
background information and safety warnings, but contained no illustrations or schematics. As
mentioned above, operational instructions were absent or very limited. Also, there was no
section in the manual regarding the power supply or its connections or troubleshooting.
However, instructions on the power supply unit were received from Xantrex with the
replacement unit. These instructions were somewhat helpful in troubleshooting later problems.
The index of the manual reflected erroneous page numbers. Furthermore, there are six or seven
appendices listed in the index of the Manual which were not provided. ARCADIS suggests that
OXI provides a (ring-)bound operations and maintenance manual with the unit that makes ample
use of illustrations and schematics and includes comprehensive operational instructions.
4.2 Disinfectant Production Capabilities (Task 1)
Sodium chloride was added to the OXI-2B unit by the operator as required. Table 4-1 provides
an overview of the frequency and amount of salt added to the system. A total of 240 lb of salt
was used during the test. It should be noted that most salt was added during the first part of the
test. During the first 10 days, 120 lbs was added and during the last 10 days, only 40 lbs was
added. Because potable water was used to dissolve the salt, a similar observation regarding
usage can be made for the potable water use (see below). The OXI 2B system is required to have
a slight brine overflow (see page 14) and during the first part of the test this brine overflow was
considerable. ARCADIS continued to decrease the output of the brine pump until the overflow
was significantly less.
20
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Table 4-1. Sodium Chloride Consumption
Day of test Date Amount of salt added
1
6/26
80
10
7/5
40
12
7/7
40
17
7/12
40
27
8/9
20
29
8/11
20
30
8/12
Verified that all salt was used
Total salt added:
240 lbs.
Typically the OXI-2B unit will be marketed for use to disinfect partially or fully treated water.
During this ETV test however, the unit was connected to raw water, because raw water provides
a more challenging environment for the ETV-test. Potable water was used for making brine and
during sampling of the disinfectant stream. Raw water, potable water and power consumption
data are included in Table 4-2. Comprehensive daily sampling results can be found in Tables C-
1 and C-2 in Appendix C.
Table 4-2.
Flow and Electrical Reading Summary
Potable
water con-
Raw water Disinfectant
Waste-
AC Volt
AC Amp
DC Volt to
DC Amp to
sumption
flow
Stream flow
water flow
(Line)2
(Linef
cell3
cell
(gal/day)
(gal/min)
(gal/min)
(ml/min)
(V)
(A)
(V)
(A)
Average
3351
23
2.9
14.1
118.2
1.2
4.2
18.1
Standard
Deviation
n/a
1
0.1
10.8
2.5
0.0
0.2
0.4
Sample size
n/a
52
30
38
12
12
29
29
Minimum
n/a
20
2.7
3
114.4
1.1
3.8
17.8
Maximum
n/a
25
3.0
54
121.2
1.2
4.5
20
95% Conf.
Int.4 Min.
n/a
23
2.8
10.6
116.8
1.1
4.1
17.9
95% Conf.
Int.4 Max.
n/a
23
2.9
17.5
119.6
1.2
4.3
18.2
Calculated from cumulative reading.
2 incoming current, collected daily from day 19 to day 30 with hand held meter.
3 Reading of DC current to electrolytic cell on Xantrex display.
4 Confidence Interval
During the test the raw water flow rate was maintained at the set rate of 23 gpm. The flow rate
was checked three times per 24 hours and adjusted, if necessary. Because the verification test
lasted 725 hours, 1.00 million gallons (3.79 million L) of raw water were treated. Based on the
recordings of the totalizer, the amount of water consumed during the 30-day (725 hour) test was
10,040 gallons (or 335 gal/day or 0.23 gal/min). During the first 10 days of the test 7,519
21
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gallons were used and during the last 10 days of the test 1,379 gallons were used, because the
brine overflow was continuously adjusted downward until minimum overflow was reached.
The disinfectant stream, which is the side stream of the raw water into which the oxidant was
aspirated, was 2.8 gal/min with a standard deviation of 0.3 gal/min or a cumulative total of
121,800 gal with a standard deviation of 13,050 gal (461,061 L with a standard deviation of
49,399 L) for the duration of the ETV test. There was a significant variation in this flow because
the valve leading into this line was very touchy and drew occasional air bubbles, which caused
turbulence into the stream just before the rotometer. Hence, the high variability in this value
may be attributed in part or completely to inaccurate rotometer readings. This condition did not
affect the disinfectant capabilities of the OXI, however, as can be seen in the Section 4.1.3.
ARCADIS recommends that OXI Company considers providing engineering support that
includes ancillary equipment selection and testing when an OXI unit is placed in the field.
Unfortunately, the Xantrex power totalizing meter that had been installed on the OXI ingoing
AC electricity line did not function properly. As soon as this was noticed, on day 18, ARCADIS
decided to start taking manual volt and current measurements. Average voltage was 118.2 V and
average current was 1.2 A, translating into a power consumption of 139 Watt. As can be seen in
summary Table 4-2, both values showed very little variability, therefore it is acceptable to
assume that during the time that no readings were taken, the power consumption also was 139
Watt. Because the ETV test lasted 725 hours, the energy consumption is estimated at 101 kWhr.
Because the total amount of water treated was 1.00 million gallons, 0.101 Whr was required to
treat one gallon of water. The OXI unit also displays the DC voltage and current that is used in
the electrolytic cell. Average voltage was 4.2 V and average current was 18 A, which is
equivalent to a DC power consumption of 76 Watt.
The OXI-2B system produced and dosed oxidant (measured as chlorine) constantly and
effectively during the test. Table 4-3 includes summarized residual free and total chlorine data
for raw and finished water, as well as for the concentrated disinfectant stream. Comprehensive
daily data are included in Appendix F. All chlorine analyses were done onsite in the SJWD
laboratory.
22
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Table 4-3. Free and Total Chlorine Concentrations
Raw
Potable
Potable
Disinfectant Disinfectant
Finished
Finished
Water,
Raw Water,
Water,
Water,
Stream,
Stream,
Water,
Water,
Free CI
Total CI
Free CI
Total CI
Free CI
Total CI
Free CI
Total CI
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
(mg/L)
Average
0.02
0.03
0.98
1.18
38
42
3.07
3.54
Standard
Deviation
0.02
0.02
0.27
0.15
9
8
0.92
0.93
Sample size
53
52
3
4
59
59
59
59
Minimum
<0.01
<0.01
0.67
0.98
13
20
1.10
1.40
Maximum
0.1
0.15
1.15
1.35
60
62
5.80
6.90
95% Conf. Int.
Minimum
0.00
0.03
0.68
1.03
36
40
2.83
3.31
95% Conf. Int.
Maximum
0.02
0.04
1.28
1.32
41
43
3.30
3.78
The raw water had an average free chlorine concentration of 0.02 mg/L, whereas the total
chlorine concentration was 0.03 mg/L. Due to the nature of raw water, minimum and maximum
values varied significantly and the standard deviation was in the same range as the average value.
The average finished free and total chlorine concentrations were 3.07 and 3.54 mg/L
respectively. Standard deviations are included in the table but are not believed to be meaningful
in the case of raw and finished water, because there are constituents in the raw water that will
affect residual chlorine.
The average total chlorine concentration for the concentrated disinfectant stream was 42 mg/L
with a standard deviation of 8 mg/L, and consisted of mainly free chlorine (38 mg/L with a
standard deviation of 9 mg/L). There was significant fluctuation in the free chlorine cf the
disinfectant stream with minimum and maximum values being 13 and 60 mg/L. In order to
obtain an accurate measurement, the oxidant gas was aspirated into SJWD potable water and not
into raw river water. The potable water free and total chlorine concentrations were 0.98 mg/L
with a standard deviation of 0.27 mg/L and 1.18 mg/L with a standard deviation of 0.15 mg/L
respectively. Therefore the true free and total chlorine content of the disinfectant stream was 37
mg/L with a standard deviation of 9 mg/L and 41 mg/L with a standard deviation of 8 mg/L
respectively. Because the total volume of the disinfectant stream generated was 510,407 L, the
total chlorine produced during the ETV-test was 21 kg (46 lb). The amount of salt used was 240
lbs, so for each pound of total chlorine 5.2 lbs of salt were needed. However, if we only take the
last 10 days of the test into account, 40 lb of salt was needed to produce approximately 7 kg (15
lb) of chlorine. In this case, the ratio of chlorine to salt is 2.7. Based on Faraday's Law (see
Appendix H), it is possible that during prolonged adjustments or with sufficient OXI-operator
help, the salt consumption can be further reduced, but this was not shown during this ETV test.
OXI informs NSF that they will undergo additional field data collection to substantiate this
further reduction. OXI also reports that the newer models of the OXI disinfectant systems do not
include a brine overflow, which they indicate was a cause of the higher salt consumption during
verification testing.
23
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4.3 Microbiological Contaminant Inactivation (Task 2)
The results of a tracer test on a previously assembled, 4-tank system revealed an HRT of 34
minutes. All tanks in the 4-tanks system were of equal size. Two of the tanks in the 4-tank
system were used in the OXI-2B 2-tank system. Dividing the 34-minute HRT of the 4-tank
system in half results in an HRT for the 2-tank system of 17 minutes. For the purposes of this
challenge test, ARCADIS conservatively assumed the HRT of the 2-tank system to be 20
minutes.
ARCADIS performed a challenge test to assess the disinfection capabilities of the OXI-2B
system on P. aeruginosa. The challenge test was conducted on August 16, 2000. The field notes
on the challenge testing are included in Appendix C. The results of the August 16 challenge test
are found in Table 4-5. The target concentration for P. aeruginosa in the broth culture was 5.0 x
1010 CFUs/100 ml. Magellan Laboratories, who supplied the P. aeruginosa, quantified it in the
whole broth at 1.6 x 1010 CFUs/100 ml. The difference in the delivered broth concentration and
the target is not considered to be significant. Approximately one gallon of this cell suspension
was shipped to the SJWD Water Treatment Plant on ice.
The broth was sub sampled at the beginning and end of the challenge test to create two trip
controls that remained on ice during the bacterial challenge-testing interval and were shipped to
the analytical laboratory with the post-treatment samples. The results of analysis on these two
trip controls can be found in Table 4-4 identified as XBC-1 (collected at challenge test initiation)
and XBC-2 (collected at challenge test completion). These values compare favorably with the 1\
aeruginosa concentration provided by Magellan Laboratories for the broth suggesting that the
microorganisms remained viable during the challenge test interval.
The raw river water was sampled at the beginning and completion of the challenge test to
establish the background concentration of native P. aeruginosa. The analytical results for these
samples identified as XRW pre and XRW post can be found in Table 4-4. XRW pre was below
the detection limit (< 1 viable P. aeruginosa cells/100 ml) and the analysis performed on XRW
post by EHL resulted in filters with colonies too numerous to count. Using the most dilute
sample tested by EHL, ARCADIS determined that P. Aeruginosa in this sample that was
reported as too numerous to count exceeded 800 CFU/100 ml. XRW post was collected from the
same sample port that was used for P. aeruginosa injection. Despite what seemed like adequate
flushing, it is believed that the organisms present in XRW post resulted from the use of the same
injection/sampling port.
Three separate positive control samples were collected from the effluent of Contact Tank 2 after
spiking P. aeruginosa into the raw water stream for three hydraulic residence times (60 minutes).
The third positive control sample was collected in duplicate. The positive control samples are
identified in Table 4-4 as XPC-60, XPC-70, XPC-80A, and XPC-80B with XPC-80A and XPC-
80B being duplicate samples.
24
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Table 4-4. Bacterial Challenge Test Results
ARCADIS
EHL
Sample
Collection
P. aeruginosa
Sample I.D.
Laboratory
Description
Date
Concentration
Sample I.D.
(CFU/100 mL)
XBC-1
524071
P. aeruginosa spiking broth prior to challenge test
8/16/00
1.5E+10*
XRW Pre
524061
P. aerug. background in raw water prior to challenge test
8/16/00
< 1
XPC-60
524018
Positive Control-Contact Tank 2 Effluent @
160 min.
8/16/00
3.3E+04
XPC-70
524020
Positive Control-Contact Tank 2 Effluent @
170 min.
8/16/00
1.1E+04
XPC-80A
524023
Duplicate Pos. Control - Contact Tank 2 Effl.
@80 min.
8/16/00
1.1E+04
XPC-80B
524026
Duplicate Pos. Control-Contact Tank 2 Effl.
@ 80 min.
8/16/00
1.3E+04
XPC-901
524068
Additional Sample-Contact Tank 2 Effl. @ 90 min.
8/16/00
<1
XPC-951
524065
Additional Sample-Contact Tank 1 Effl. @ 95 min.
8/16/00
<1
XT1-140
524029
Treated Sample - Contact Tank 1 Influent @
1140 min.
8/16/00
3.1E+02
XBT-140
524032
Treated Sample - Between Contact Tanks (5
5140 min.
8/16/00
7.9E+02
XT2-140
524037
Treated Sample - Contact Tank 2 Effluent @
! 140 min.
8/16/00
< 1
XT1-150
524038
Treated Sample - Contact Tank 1 Influent @
1150 min.
8/16/00
2.8E+02
XBT-150
524041
Treated Sample - Between Contact Tanks (5
5150 min.
8/16/00
1.0E+01
XT2-150
524046
Treated Sample - Contact Tank 2 Effluent @
! 150 min.
8/16/00
< 1
XT1-160
524048
Treated Sample - Contact Tank 1 Influent @
1160 min.
8/16/00
1.3E+02
XBT-160
524052
Treated Sample - Between Contact Tanks (5
5160 min.
8/16/00
< 1
XT2-160A
524055
Duplicate Treated Sample-Cont. Tank2 Effl. @ 160 min.
8/16/00
<1
XT2-160B
524058
Duplicate Treated Sample-Cont. Tank2 Effl @ 160 min.
8/16/00
<1
XBC-2
524074
P. aeruginosa spiking broth post challenge test
8/16/00
2.2E+10*
XRW post
524062
P. aeruginosa background in raw water post challenge test
8/16/00
> 800
concentration generated using SM9215 B
samples taken after initiation of oxidant gas injection/not included in statistical calculations.
(These samples were in addition to those required in the FOD protocol)
During the challenge test, treated and finished water samples were collected simultaneously from
three individual sample points within the system at sequential, 10-minute intervals. The first
sample point was in the raw water feed supply pipe following the dosage points for both P.
aeruginosa and oxidant gas and in-line mixing (contact time with disinfectant ~ 20 seconds).
The second sample point was installed in the pipe transferring water from Contact Tank 1 to
Contact Tank 2 (contact time with disinfectant =10 minutes). The third and final sample point
was at the effluent of Contact Tank 2 (contact time with disinfectant = 20 minutes). Treated
samples were collected at 140 minutes, 150 minutes, and 160 minutes into the challenge test. All
samples collected from the raw water pipe feeding Contact Tank 1 can be distinguished by the
ARCADIS sample prefix "XT1". All samples collected from the piping between Contact Tank 1
and Contact Tank 2 can be distinguished by the ARCADIS sample prefix "XBT". All samples
collected at the effluent of Contact Tank 2 can be distinguished by the ARCADIS sample prefix
"XT2". The sample collected at the Contact Tank 2 effluent at 160 minutes of elapsed time was
collected in duplicate leading to the designations XT2-160A and XT2-160B.
The P. aeruginosa enumeration of the positive control samples ranged from 1.1 x 104CFUs/100
ml to 3.3 x 104 CFUs/100 ml with a log average of 1.5 x 104 CFUs/100 ml. The control samples
were sequentially collected at ten-minute intervals from the finished water leaving Contact Tank
2 after spiking the raw water with P. aeruginosa for three hydraulic retention times. The 95
25
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percent confidence interval bounding positive control enumeration is 6.5 x 103 CFUs/100 ml to
3.5 x 104 CFUs/100 ml with three degrees of freedom. Figure 4-1 is a graphic portrayal of the
positive control sample enumerations. Figure 4-2 shows the mean of the positive control
enumerations. Additionally, the statistically calculated 95 percent confidence interval is
displayed on Figure 4-2.
i
g 1.0E+05 -i—
y, 1.0E+04 — ¦ — — —
I
E0E+03 H H -
!
^ E0E+02 HH —
0
•S
1 E0E+01 -I ^^^
I XPC-60 XPC-70 XPC-80A XPC-80B
XPC-60 = positive control @ 60 minutes
XPC-70 = positive control @ 70 minutes
XPC-80A = duplicate positive control @ 80 minutes
XPC-80B = duplicate positive control @ 80 minutes
Figure 4-1. Bar Graph of Bacterial Challenge Test Positive Control Samples
Figure 4-2. Mean Enumeration Values of Positive Control Samples
26
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Though OXI-2B treated samples were collected at three different sampling points during the
challenge test, only data from the Contact Tank 2 effluent need be statistically analyzed to
evaluate the 4-log reduction performance claim. It can be visually determined that data from the
other two sampling points does not approach a 4-log reduction. The P. aeruginosa enumeration
of the effluent samples collected from Contact Tank 2 were all below the detection limit of the
filtered sample volumes or < 1 CFU/lOOml. In order for errors to be considered conservative,
samples reported as being less than the detection limit were treated as if they contained 1
CFUs/100 ml. Because these treated samples all resulted in enumeration results that were below
the detection limit, ARCADIS did not prepare graphical representations of the data or the mean
of the treated effluent samples.
Enumerations for the four positive control samples (XPC-60, XPC-70, XPC-80A, and XPC-80B)
demonstrate that a P. aeruginosa was recovered at a log-average concentration of 1.5 x 104
CFUs/100 ml. Enumeration for the four treated samples recovered from Contact Tank 2 effluent
indicate a survival of 1 CFUs/100 ml using worst-case approximations. The log removal of P.
aeruginosa is calculated below.
log removal of P. aeruginosa = log10
log removal of P. aeruginosa = log10
[1.0x10 CFU/ml
log removal of P. aeruginosa = 4.2
The results of the P. aeruginosa challenge test show that the OXI-2B system is capable of a 4-
log kill of P. aeruginosa at a CT value of 56 based on calculated hydraulic retention time (17
minutes) or a CT of 30 based on a Tio value (9 minutes).
Using the free chlorine concentrations found in Table 4-5 and actual hydraulic retention time (17
minutes), the CT value calculated prior to the commencement of bacterial injection is 56. The
calculated CT value using a sample collected near the completion of the challenge test (using
0.20 mg/L and 17 minutes as a HRT) is 3.4. ARCADIS contends that this CT value is artificially
depressed by the inadvertent injection of the organic material associated with the P. aeruginosa
growth broth along with the microorganism. ARCADIS believes that the nonbiological organic
compounds present in the growth broth consumed substantial oxidant leading to the free and total
chlorine results presented in Table 4-5. Despite the resultant, depressed CT values calculated for
the challenge test, the OXI-2B challenge test data support a 4-log reduction in P. aeruginosa
during the test.
(CFU/ )
V /ml ' feedwater
[CFU/ )
/ml effluent
~1.5xl04 CFU I ml
1.0x10° CFU / ml
27
-------
Table 4-5. Results of Total and Free Chlorine Testing During Bacterial Challenge
Testing
Sample
Description
Prior to Bacterial Injection
Free Chlorine
(mg/L)
Total Chlorine
(mg/L)
During Bacterial Injection
(near challenge test conclusion)
Free Chlorine Total Chlorine
(mg/L) (mg/L)
Treated Water
(Contact Tank 1)
Finished Water
(Contact Tank 2)
2.70
3.30
3.50
3.10
0.70
0.20
3.10
1.70
See Appendix C, daily log sheet, dd. 8/16
4.4 Finished Water Quality (Task 3)
This section presents results for water quality data that were collected during the test. Daily raw
water and finished water levels of pH, temperature and turbidity are reflected in Table 4-6. The
average raw water pH was 7.27 with a standard deviation of 0.39. The average pH for finished
water was 6.63. The OXI unit had a slight decreasing effect on pH, because the pH of the
disinfectant side stream was acidic (3.75). On the other hand, the waste stream was very basic
with a pH of 12.91. None of the pH values for treated, finished, or disinfectant stream showed
much variability, which indicates that the disinfectant output of the OXI was stable as far as pH.
Table 4-6. Summary of Daily pH, Temperature, and Turbidity Readings
pH, Dis-
Turb
Turb
Turb
PH,
infectant
PH,
PH,
PH,
Temp,
Temp,
Temp,
(grab),
(grab),
(in-line),
Raw
Stream
T reat.
Fin.
Waste
Raw
Fin.
Waste
Raw
Fin.
Fin.
°C
°C
°C
NTU
NTU
NTU
Average
7.20
3.76
6.63
6.63
12.91
24.6
24.8
27.4
11.45
11.67
10.92
St. Dev.
0.12
0.141
0.15
0.15
0.244
1.2
1.3
2.4
16.85
17.68
18.79
Minimum
6.97
3.49
6.14
6.10
12.27
22.0
22.0
23.8
5.16
4.26
0.47
Maximum
7.98
3.93
7.89
7.86
13.37
26.5
27
34.5
90.40
94.00
96.83
95% Conf. Int.
Minimum.
7.15
3.69
6.58
6.57
12.82
24.2
24.3
26.4
5.42
5.35
3.84
95% Conf. Int.
Maximum
7.24
3.83
6.69 6.68 13.01
25.1
25.2
28.4
17.48
18.00
18.01
Temperature readings were taken twice daily for raw2, finished, and wastewater. The OXI-2B
system had no effect on the finished water temperature. The temperature of the waste stream
was higher than that of the water stream. Most likely, this increase was governed by exposure to
ambient temperature. In-line turbidity readings were taken twice daily for finished water and
2 As of day 19, the Treated water temperature readings were used as a surrogate for Raw water temperature readings.
It was expected that the Raw water temperature readings were inaccurate, because the Raw water had to be sampled
with a beaker, whereas the Treated water could be sampled in the top of the first tank. This sampling location was
very close to the Raw water sampling port, so it is expected that the Treated water reading accurately reflects the
Raw water reading.
28
-------
were verified by taking grab samples. Also, raw water grab samples were analyzed for turbidity.
The OXI-2B system has no apparent effect on turbidity: the average raw water turbidity was
11.45 NTU and the average finished water turbidity was 11,67 NTU for grab samples and 10,92
NTU for in-line samples. A turbidity spike occurred on day 22 as a result of a storm, when the
turbidity rose to over 90 NTU. This event caused the standard deviation to be higher than the
average.
Table 4-7 includes results of additional weekly and biweekly sampling. Hydrogen sulfide,
alkalinity and TDS were analyzed on-site by SJWD, whereas all other samples were sent off to
be analyzed by EHL. The OXI-2B waste stream has very high TDS and alkalinity as well as a
corresponding high pH. The OXI-2B has no apparent effect on either UVA, true color, TOC,
manganese, and iron. (One TOC finished water reading was 29 mg/L, whereas the three other
readings were between 1.9 and 2.8 mg/L. The high reading is believed to be recorded
erroneously. See Summary Table D-l, Appendix D). Readings3 for chlorite and chlorate were
always below the detection limit of 20 |_ig/L. The OXI-2B system produced some chloride (6.0
mg/L), which can probably be attributed to the use of brine. The sodium went down in the
finished water, indicating that sodium is removed by the membrane. Ammonia nitrogen was not
detected in raw nor finished water.
Table 4-8 includes data for coliforms and HPC. The OXI-2B system performed well in
eliminating total coliforms. For all test days, total coliforms were reduced to zero cfu/100 ml
and therefore, the log inactivation was not calculated (see Table 4-9). The OXI-2B system was
very effective in reducing HPC during the first 20 days of the test, but for the remaining 10 days
of the test, the HPC kill capacity may have diminished. Although ARCADIS has no complete
explanation for this phenomenon, the concentration of heterotrophic bacteria in the raw water
samples generally increased by an order of magnitude during this same interval. Although the
disinfectant (as chlorine) output remained stable during the same interval, the higher
concentrations of heterotrophic microorganisms may be indicative of other changes in raw water
characteristics which may account for decreased disinfectant performance such as an increase in
total organic carbon. Because total organic carbon was not a daily analyte in this verification
program, such an increase may go undetected. Other changes in raw water characteristics that
might affect the disinfection capabilities of the OXI-2B such as turbidity were not noted during
this interval. Also, during this time, the coliform inactivation remained maximal. It is unlikely
that possible decrease in performance is a sampling induced phenomenon. Finished water
samples were dipped from contact tank 2. Because the samples were not removed from a
sampling port in the effluent discharge pipe, there was not opportunity for the samples to be
contaminated by microorganisms potentially growing in the effluent discharge pipe or sample
port itself.
3 Chloride = CI ; chlorate = CIO3 ; chlorite = CIO2 .
29
-------
Table 4-7. Miscellaneous Weekly and Biweekly Data
95% Conf. 95% Conf.
Unit
Lab
Average
St Dev
Min.
Max.
Int. Min
Int. Max
H2S, Raw
ng/L
SJWD
<2
n/a
<2
<2
n/a
n/a
Alkalinity, Raw
mg/L
SJWD
19
0.9
18
20
18
20
Alkalinity, Finished
mg/L
SJWD
16.2
2.9
13
21
14
19
Alkalinity, Waste
mg/L
SJWD
30,960
10,585
24,960
41,280
25,023
44,737
TDS, Raw
mg/L
SJWD
68
11
60
76
52
84
TDS, Finished
mg/L
SJWD
16
0
16
16
16
16
TDS, Waste
mg/L
SJWD
13,800
n/a
7,480
20,120
n/a
n/a
UVA (UV 254), Raw
1/cm
EHL
0.19
0.06
0.14
0.27
0.13
0.25
UVA (UV 254), Finished
1/cm
EHL
0.19
0.08
0.13
0.3
0.11
0.27
True Color, Raw
Pt/Co units
EHL
65
24
50
100
42
88
True Color, Finished
Pt/Co units
EHL
70
22
50
100
49
91
Ammonia Nitrogen, Raw
mg/L
EHL
<0.3
n/a
<0.3
<0.3
n/a
n/a
Ammonia Nitrogen, finished
mg/L
EHL
<0.3
n/a
<0.3
<0.3
n/a
n/a
TOC, Raw
mg/L
EHL
2.2
0.5
1.8
2.6
1.8
2.7
TOC, Finished
mg/L
EHL
2.4
13.3
1.9
29
2.0
2.9
Chloride, Raw
mg/L
EHL
2.4
0.2
2.2
2.6
2.2
2.5
Chloride, Finished
mg/L
EHL
6.0
0.5
5.5
6.6
5.5
6.5
Chlorate, Raw
ng/L
EHL
<20
n/a
<20
<20
n/a
n/a
Chlorate, Finished
ng/L
EHL
<20
n/a
<20
<20
n/a
n/a
Chlorite, Raw
ng/L
EHL
<20
n/a
<20
<20
n/a
n/a
Chlorite, Finished
ng/L
EHL
<20
n/a
<20
<20
n/a
n/a
Manganese, Raw
ng/L
EHL
145
n/a
120
170
n/a
n/a
Manganese, Finished
ng/L
EHL
130
n/a
100
160
n/a
n/a
Iron, Raw
ng/L
EHL
1.7
n/a
1.4
2.0
n/a
n/a
Iron, Finished
ng/L
EHL
1.6
n/a
1.2
2.0
n/a
n/a
Sodium, Raw
mg/L
EHL
15.2
n/a
3.3
27.0
n/a
n/a
Sodium, Finished
mg/L
EHL
5.4
n/a
3.3
7.4
n/a
n/a
n/a: standard deviation not applicable because values were below detection limit or sample size is
too small.
30
-------
Table 4-8. Total Coliforms and Heterotrophic Plate Counts
Total
Total
Log
Log
Day
Coliforms,
Coliforms,
Inactivation
HPC,
HPC,
Inactivation
Raw
Finished
Coliforms
Raw
Finished
HPC
#/100 ml
#/100 ml
CFU/ml
CFU/ml
1
144
< 20
>0.9
300
1
2.5
2
500
< 20
>1.4
114
< 1
>2.1
3
800
< 20
>1.6
416
1
2.6
4
200
< 20
>1.0
208
2
2.0
5
350
< 20
>1.2
237
2
2.1
6
**
**
**
**
**
**
7
**
**
**
**
**
**
8
250
< 20
>1.1
244
< 1
>2.4
9
400
< 20
>1.3
108
2
1.7
10
**
**
**
**
**
**
11
< 1000
< 20
**
192
< 1
>2.3
12
350
< 20
>1.2
182
1
2.3
13
**
**
**
**
**
**
14
**
**
**
**
**
**
15
250
< 20
>1.1
150
1
2.2
16
300
< 20
>1.2
192
< 1
2.3
17
1400
< 20
>1.8
1820
5
2.6
18
300
< 20
>1.2
**
**
**
19
50
< 20
>0.4
2756
4
2.8
20
700
< 20
>1.5
1560
1
3.2
21
150
< 20
>0.9
1664
77
1.3
22
1400
< 20
>1.8
1820
214
0.9
23
**
**
**
**
**
**
24
**
**
**
**
**
**
25
900
< 20
>1.7
>5200
416
>1.1
26
1000
< 20
>1.7
988
832
0.1
27
600
< 20
>1.5
98
39
0.4
28
700
< 20
>1.5
316
18
1.2
29
650
< 20
>1.5
168
216
-0.1
30
**
**
**
**
**
**
= no data collected
Total trihalomethanes (TTHMs) and haloacetic acids (HAAs) were also analyzed as part of the
ETV verification project and the results are included in Table 4-9. None of the analytes were
detected in the raw water. The OXI-2B system generated some chloroform (10 |_ig/L) and small
amounts of bromodichloromethane (2.8 |_ig/L) and dibromochloromethane (0.3 |~ig/L), whereas
none of the other TTHMs were detected. As far as HAAs, average dichloroacetic acid and
trichloroacetic acid concentrations were 18 |j,g/L and 21 |_ig/L respectively. Small amounts of
bromochloroacetic acid, monochloroacetic acid, and bromodichloroacetic acid were detected.
No other HAAs were detected.
31
-------
Table 4-9. TTHMs and HAAs
Parameter
Unit
Jul 7
Aug 8
Aug 16
Average
TTHMs
Bromodichloromethane, Raw
ng/L
<0.1
<0.1
<0.1
<0.1
Bromodichloromethane, Finished
ng/L
2.0
3.6
<0.1
1.9
Chloroform, Raw
ng/L
<0.1
<0.1
<0.1
<0.1
Chloroform, Finished
ng/L
5.6
15
<0.1
6.9
Bromoform, Raw
ng/L
<0.1
<0.1
<0.1
<0.1
Bromoform, Finished
ng/L
<0.1
<0.1
<0.1
<0.1
Dibromochloromethane, Raw
ng/L
<0.1
<0.1
<0.1
<0.1
Dibromochloromethane, Finished
ng/L
0.3
0.4
<0.1
0.3
HAAs
Bromochloroacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Bromochloroacetic acid, Finished
ng/L
XX
2.5
2.3
2.4
Dibromoacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Dibromoacetic acid, Finished
ng/L
XX
<0.1
<0.1
<0.1
Dichloroacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Dichloroacetic acid, Finished
ng/L
XX
20
15
18
Monobromoacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Monobromoacetic acid, Finished
ng/L
XX
<0.1
<0.1
<0.1
Monochloroacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Monochloroacetic acid, Finished
ng/L
XX
<0.1
4.0
2.1
Trichloroacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Trichloroacetic acid, Finished
ng/L
XX
26
16
21
Bromodichloroacetic acid, Raw
ng/L
XX
<0.1
<0.1
<0.1
Bromodichloroacetic acid, Finished
ng/L
XX
2.5
2.0
2.3
XX = not required
Note: If one or more samples were below the detection limit, the detection limit was used
to calculate averages.
Furthermore, ARCADIS conducted simulated distribution system (SDS) testing to determine the
extent to which disinfection byproducts would be formed using effluent from the OXI-2B system
while dosing it with additional OXI disinfectant stream. This test was performed because the
OXI system can be used for both primary and residual disinfection. Five 1-liter effluent samples
were collected, pH-adjusted to approximately 8.2, spiked with effluent from the disinfectant
stream (at 25, 50, 75, 100, and 150 ml dosing rates) and incubated for 24 hours at 20 °C. In
addition, a deionized water sample was collected, spiked, and incubated to which 100 ml water
from the disinfectant stream was added. Lastly, a sample of OXI finished water was incubated
with no additional water from the disinfectant added. After incubation, the five OXI samples
were analyzed for residual chlorine. The 50 ml-dosed sample contained 2.32 mg/L residual
chlorine and was shipped to the analytical laboratory along with the deionized water and SJWD
finished water sample and the unamended OXI finished water sample. The results of the SDS
testing are presented in Table 4-10.
32
-------
Table 4-10. Simulated Distribution System Test Results
Unit
LTB
Dl Water
+ 100 ml
SJWD-OXI
Finished
SJWD-OXI
+ 50 ml
TTHM Analvtes
Bromodichloromethane
CO
r5
<0.1
0.8
11
9.9
Bromoform
CO
r5
<0.1
<0.1
<0.1
<0.1
Chloroform
CO
r5
<0.1
12
86
85
Dibromochloromethane
CO
r5
<0.1
<0.1
0.8
0.7
HAA Analvtes
Bromochloroacetic acid
ng/L
**
<1.0
4.2
4.1
Dibromoacetic acid
ng/L
**
<1.0
< 1.0
<1.0
Dichloroacetic acid
Hg/L
**
6.8
46
50
Monobromoacetic acid
Hg/L
**
<1.0
< 1.0
<1.0
Monochloroacetic acid
Hg/L
**
2.1
5.3
6.3
Trichloroacetic acid
Hg/L
**
9.3
78
91
Bromodichloroacetic acid
^g/L
**
<1.0
4.3
4.6
LTB = laboratory trip blank
** = no data collected
Testing included analyses for TTHMs and HAAs. DBPs were below the detection limits in the
laboratory trip blank (LTB). The deionized water blank with OXI-2B disinfectant added was
found to contain 0.8 |ig/L bromodichloromethane, 12 |ig/L chloroform, 6.8 |_ig/L dichloroacetic
acid, 2.1 |ig/L monochloroacetic acid and 9.3 |_ig/L trichloroacetic acid. The OXI finished water
and the OXI "finished + 50 ml" sample had comparable amounts of DBPs. Both had significant
amounts of chloroform (~ 85 |_ig/L), dicholoracetic acid (46-50 |~ig/L), and trichloroacetic acid
(78-91 Hg/L) and relatively low levels of bromodichloromethane (9.9-11 |ig/L),
dibromochloromethane (0.7-0.8 |ig/L), bromochloroacetic acid (4.1-4.2 |ig/L), monochloroacetic
acid (5.3-6.3 |ig/L), and bromodichloroacetic acid (4.3-4.6 |ig/L).
In a typical drinking water treatment plant, it is customary to remove dissolved organics from the
raw water prior to treatment with chlorine. Removal of dissolved organics prior to chlorination
can minimize DBP formation. The support system designed for the verification of the OXI-2B
during this project was not designed to remove dissolved organics from the raw water prior to
chlorination. Thus, the formation of substantial quantities of DBPs during the verification
interval is not a surprising result. It should be noted that ARCADIS believes that the potential
for formation of DBPs is specific to the raw water source and to the degree of dissolved organic
pre-treatment applied prior to chlorination. The results shown in Table 4-10 illustrate how the
OXI-2B performed with regard to DBP formation in the setting established for the verification
testing and using raw water from the Middle Tyger River.
4.5 Waste Production
The OXI produced a small continuous waste stream of 13.7 ml/min, so for the duration of the
test (725 hours) 596 liters (157 gal) of waste was produced (Table 4-2). On a daily basis, 5.2 gal
33
-------
(19.8 L) of waste was produced. A heavy metals analysis on the waste stream was performed as
a one-time event (see Table 4-11). As was indicated in Tables 4-6 and 4-7, the waste stream had
a high alkalinity, pH, and a high TDS content. The average alkalinity of the waste was 30,960
mg/L, the pH was 12.91, and the TDS was 13,800 mg/L. No sodium or sodium hydroxide
samples were taken from the waste stream. The concentration of sodium in the waste stream
may be estimated based on the sodium chloride consumption, which was 4 lbs (or 1.82 kg or 31
moles) per day during the last ten days of the test. As mentioned, during the last ten days of the
test the salt dosage had been adjusted more effectively compared to the first 20 days of the test.
Because the average daily wastewater generation was 19.8 L, the sodium concentration in the
waste stream can be estimated at 1.57 mol/L or 36 g/L.
According to OXI documentation, the OXI-2B cathode generates 11.2 L of hydrogen for each
35.5 gram of total chlorine. Because 21 kg total chlorine were generated, 6,625 L of hydrogen
were produced over the duration of the verification test. A fitting and a tube on the cathode
compartment lid are used to vent this small amount of hydrogen produced to a safe distance
away from the generator.
Table 4-11. Results of Heavy Metal Analysis on Water
Softener Regeneration Waste Stream
Analyte
Analytical Method
Concentration (|ig/L)
Antimony
USEPA 200.8
< 42.2
Arsenic
USEPA 200.8
< 105.5
Beryllium
USEPA 200.8
< 42.2
Cadmium
USEPA 200.8
< 42.2
Chromium
USEPA 200.8
< 42.2
Copper
USEPA 200.8
< 105.5
Lead
USEPA 200.8
< 105.5
Mercury
USEPA 200.8
< 105.5
Nickel
USEPA 200.8
< 105.5
Selenium
USEPA 200.8
< 422.0
Silver
USEPA 200.8
< 42.2
Zinc
USEPA 200.8
170
34
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Chapter 5
Quality Assurance
5.1 Calculation of DQI Goals
Table 5-1 shows the data quality indicator (DQI) goals established for accuracy and precision
presented in the OXI FOD. The calculated DQIs for the majority of the parameters listed in
Table 5-1 are presented in Table 5-2. These DQIs were calculated using data from replicate
analysis of laboratory or field QA/QC checks for each parameter. Obtained values represent the
average of all replicate measurements. The number of replicates for each parameter is shown in
parentheses. Accuracy was assessed by calculating recovery of spikes or surrogates or by
calculating the bias from an obtained value compared to a known standard. Precision is
expressed as percent relative standard deviation (RSD) and is calculated by dividing the standard
deviation of replicate measurements by the mean. The 95 percent confidence intervals have also
been calculated for data sets that contained at least three replicate measurements. It can be seen
in Table 5-2 that DQI goals were met for chlorate/chlorite, iron, ammonia-nitrogen, sodium,
TDS, total organic carbon, manganese, pH, free chlorine, and turbidity measurements.
Table 5-1. Data Quality Indicator Goals for Critical Measurements
Parameter
Method
Accuracy
Precision
(%RSD)
Flow Rates
PH
Temperature
MO Stream concentration
Raw Water Turbidity
Bacteria Dose Rate
Chlorine Residual
Hydrogen sulfide
Alkalinity
Total dissolved solids
Ammonia-N
Total organic carbon
Color
UVA
Iron
Manganese
Chloride
Sodium
Potassium
Total coliform
TTHMs
HAAs
Chlorite/Chlorate
Rotameters
SM 4500 H
SM2550B
4500-CI F
SM2130B
Peristaltic Pump
SM 4500-CI F
SM 4500-S2-A4C
SM2320B
SM 2540C
SM 4500-NH3 G
SM 5310C
SM2120B
SM 5910B
EPA Method 200.7
EPA Method 200.7
EPA Method 300
EPA Method 200.7
EPA Method 200.7
SM 9222B
EPA Method 524.2
EPA Method 552.1
EPA Method 300 B
+ 2 gal/minute
+ 0.1 pH unit
N/A
N/A
80-120% Rec.
+4 ml/min
N/A
90-110% Rec.
75-120% Rec.
80-120% Rec.
80-120% Rec.
80-120% Rec.
N/A
85-120% Rec.
85-115% Rec.
85-115% Rec.
90-110% Rec.
85-115% Rec.
85-115% Rec.
N/A
70-130% Rec.
70-130%
90-110% Rec.
N/A
Not listed
10
40
25
20
40
40
30
25
25
25
40
20
20
20
30
20
20
200
40
40
30
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Table 5-2. Calculated DQIs for Critical Measurements
Actual
Avg. Obtained
Recovery/Bias*
Precision
Analyte
Cone.
(# points)
(Average %)
(%RSD)
Chloride
25 ng/L
26.2 (4)
105.2
3.1
Chlorate/Chlorite
100 ng/L
96.9 (9)
94.7
2.2
Iron
1 mg/L
99.6 (2)
99.6
3.0
Ammonia-N
5 mg/L
4.59 (11)
91.8
4.1
Sodium
1 mg/L
0.93 (2)
93
0
Total Dissolved Solids
451 mg/L
(1)
467.5 mg/L
(2)
Total Organic Carbon
10 mg/L
10.09(12)
100.9
N/A
Manganese
50 ng/L
(2)
Free Chlorine
1.0 mg/L
0.92 (18)
8.0*
4.6
2.0 mg/L
1.81 (7)
9.5*
2.0
Turbidity
1.43 NTU
1.42 (4)
0.7*
17.2 NTU
17.2 (23)
0*
0.3
* - indicates that the result is presented as % bias from a known value
Parameters not addressed in Table 5-2 include flow rate, pH, temperature, alkalinity, TDS, TOC,
color, and UVA. Daily flow rate accuracy was assessed by examining daily flow measurements
and determining whether or not they were within the established 21-25 gal/min range (23 g/min
target, ±2 gal/min). There were 53 measurements of flow rate and only one measurement (Day
22 @ 20 g/min) was outside of the acceptable range. The accuracy of rotameter used to
determine raw water flow is discussed in Section 5.3. The pH meter was checked daily with
buffer solution at 2 points. Actual pH values were not recorded by the operator unless the
calibration check was not within the acceptable range. Daily data sheets indicate that the pH
meter adequately measured daily buffer checks on all test days. Temperature measurements
were made with factory calibrated thermocouples. Analyses for alkalinity, TDS, TOC, color and
UVA were performed by EHL. Laboratory reports from EHL indicate that all measurements
were within method specific acceptance criteria.
Table 5-3 presents the TTHM recovery results from surrogates spiked by EHL prior to sample
analysis by EPA Method 524.2. The surrogate standards are purchased by EHL from
AccuStandard, Inc. Representative Certificates of Analysis for the surrogate standards have been
provided by EHL and are included in Appendix C. Acceptance criteria established in the method
is 70-130 percent. It can be seen that all compounds met the acceptance criteria.
Table 5-3. Trihalomethane Recoveries (70-130% criteria)
Spiked Cone.
Bromodichloromethane
Bromoform
Chloroform
Dibromochloro methane
Date
(M/L)
Obtained
%Rec
Obtained
%Rec
Obtained
%Rec
Obtained
%Rec
7/10
2
2.26
113
2.29
114.7
2.15
107.3
2.44
121.9
10
10.98
109.8
11.36
113.6
10.26
102.6
10.69
106.9
9/1
10
9.88
98.8
9.55
95.5
10.90
109
10.92
109.2
9.64
96.4
8.76
87.6
9.53
95.3
9.66
96.6
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Table 5-4 shows the HAA recoveries of a 20 |j,g/L standard analyzed by EPA Method 552.2.
Acceptance criteria are established as 70-130 percent. All compounds fell within the acceptance
criteria for this analysis.
Table 5-4. Haloacetic Acid Recoveries for 20 jig/L Standard
(70-130% criteria)
Bromochloro
Dibromo Acetic
Dichloro Acetic
Analysis
Acetic Acid
Acid
Acid
Date
Obtained
%Rec
Obtained
%Rec
Obtained
%Rec
8/17
21.8
109
19.9
99.7
19.1
95.7
8/18
20.1
100.6
20.3
101.3
19.1
95.7
8/22
24.2
124.8
24.7
123.7
22.2
111
23.6
117.8
22.0
109.9
21.0
104.8
Monobromo
Monochloro Acetic
Trichloro Acetic
Analysis
Acetic Acid
Acid
Acid
Date
Obtained
%Rec
Obtained
%Rec
Obtained
%Rec
8/17
21.5
107.5
21.3
106.6
21.9
109.7
8/18
18.7
93.2
19.4
97.1
19.7
98.7
8/22
21.0
105.1
20.2
101.1
24.9
124.5
23.0
114.9
20.9
104.3
24.2
121.1
5.2 Blanks, Duplicates and Hold Times
Blank samples were routinely sent to the laboratories with each set of samples for analysis. Each
laboratory also ran internal laboratory and reagent blanks as a part of their daily QA/QC
procedures. Results from analysis of field and laboratory blanks did not indicate contamination
problems for any analyte of interest in this study.
During the conduct of total chlorine analyses at SJWD, 10 deionized water blanks were
analyzed. The blank analysis resulted in a range of values from 0.00 to 0.03 mg/L total chlorine.
During the conduct of free chlorine analyses at SJWD, 31 deionized water blanks were analyzed.
The blank analysis resulted in a range of values from - 0.01 to 0.01 mg/L free chlorine. The
deionized water blanks for the verification interval are shown in the OXI-2B Field Data File.
A total of 20 duplicate total chlorine samples were conducted at SJWD during the verification
interval. ARCADIS has evaluated the relative percent difference (RPD) for each pair of
duplicates. The entire data set of 20 duplicates cannot be evaluated using an RSD calculation
because it is legitimate and expected that the chlorine dosing vary subtly over time. RPD is
calculated by dividing the difference between the two duplicate analytical results by the mean for
the two analytical results. The range of RPD values for the set of total chlorine analytical
duplicates was 0 percent to 15 percent for disinfectant and finished water analyses. The
calculations for % RPD are shown in the OXI-2B Field Data File.
A total of 29 duplicate free chlorine samples were conducted at SJWD during the verification
interval. ARCADIS has evaluated the relative percent difference (RPD) for each pair of
duplicates. The entire data set of 29 duplicates cannot be evaluated using an RSD calculation
because it is legitimate and expected that the chlorine dosing vary subtly over time. RPD is
calculated by dividing the difference between the two duplicate analytical results by the mean for
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the two analytical results. The range of RPD values for the set of total chlorine analytical
duplicates was 0 percent to 25 percent for disinfectant and finished water analyses. The
calculations for % RPD are shown in the OXI-2B Field Data File. A total of 90 pH measurements
were taken over the 30-day test period. In addition, 8 duplicate pH measurements were taken
and recorded on daily data sheets by SJWD staff. Relative percent differences ranged from 0-
4.4% for the duplicate measurements.
For total coliform samples routinely taken by SJWD were used as duplicates. SJWD samples
were taken from the same raw water intake where water for the ETV test was taken. During the
test, Coliform samples for both SJWD and ETV were collected by the same person around the
same time of day. ARCADIS chose three dates randomly and compared the counts. Total
Coliform counts for the SJWD routine samples ("duplicates") for these dates were 7/6/00 (Test
Day 11) - 300 coliforms/100 rri, 7/12/00 (Test Day 17) - 1,600 coliforms/100 ml, and 8/3/00
(Test Day 21) - 150 coliforms/100 ml. The raw water sample for the OXI-2B verification test
for 7/6/00 was below the detection limits for coliforms (< 20 CFU/100 ml). The raw water
sample for the OXI-2B for 7/6/00 (Test Day 11) contained 1,400 coliforms/100 ml for a relative
percent difference of 13.3 percent. The raw water sample for the OXI-2B for 8/3/00 (Test Day
21) contained 150 CFU/100 ml, which was equal to the coliform concentration detected in the
SJWD routine sample for 8/3/00.
EHL conducted negative controls on the agar and sterile filters used for P. aeruginosa
enumeration. In addition, positive controls were conducted for the Pseudomonas isolation agar
used for incubation.
Hold times specified in the methods were met for all samples with the following exception:
samples submitted on 07/07/00 for color and UV 254 analysis exceeded the 48-hour hold time
specified in the method. The laboratory informed the Project Manager that the hold times had
been exceeded and was instructed to analyze the sample as soon as possible. In addition, the
reanalysis of sample number 524315 for mercury was analyzed outside of the 28-day hold time.
Also, for a number of the samples submitted for Method 524.2 analysis, the pH on receipt
exceeded the method requirement of a pH<2. These deviations were noted on the EHL
laboratory reports. Hold times for P. aeruginosa samples exceeded the 24-hour holding time by
6 to 15 minutes. The results from these samples were not used in the calculation of log
inactivation of P. aeruginosa.
5.3 Daily and Bi-Weekly QA/QC Verifications
As indicated in the FOD, certain parameters associated with verification testing required daily or
bi-weekly verification. The raw water flow rate and the disinfectant stream flow were recorded
using existing rotameters. The performance of the raw water flow rotameter was verified as a
function of its involvement in a previous ETV verification program. The results of this rotameter
performance evaluation are found in Appendix G. The raw water rotameter's accuracy was
confirmed with a total of twenty timed sequential events both before and during the OXI-2B
verification interval while filling the volumetrically calibrated vessels that served as contact
tanks within the system. With 23 gpm as the set point, the range in flow rates was 85 percent to
104 percent of the target flow. Finished water flow to the turbidimeter was verified daily using a
38
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timed, volumetric collection method. A minimum of 200 ml/min flow to the turbidimeter is
considered critical to assure accurate readings. The flow to the turbidimeter was verified on 29
out of 30 test days using a graduated cylinder and a stopwatch. On 7/10/00, the flow to the
turbidimeter was found to be below 200 ml/min. In this instance the turbidimeter suction tubing
was cleaned and the flow rate increases subsequently to 420 ml/min. All other turbidimeter flow
measurements exceeded 200 ml/min. A summary of this data can be found in Appendix G. The
summary was created using the actual readings recorded on daily log sheets found in Appendix
C. In-line turbidimeter readings were compared on a daily basis to readings from a calibrated
bench-top turbidimeter and recorded on the data sheets in Appendix C. Turbidity comparison
data exists for twenty-six of the thirty test days. It is known within industry that agreement
between in-line and bench-top turbidimeters is problematic (personal communication with Doug
Waldrop). The RPDs have been calculated for the twenty-six comparable data points. The
RPDs range from 0 percent to 173 percent and are summarized in Appendix G. References to in-
line rotameter maintenance and flow verification and in-line turbidimeter maintenance can be
found in the bound project notebook presented as Appendix F. Tubing and piping were visually
inspected on a daily basis. On 6/27/00, visual inspection revealed a stuck brine tank fill valve
and a ruptured potable water make-up hose. On 7/3/00, visual inspection found a stuck potable
water valve. On 7/5/00, visual inspection revealed a need to replace a 2-inch PVC union on the
discharge side of the raw water supply pump. On 8/5/00, visual inspection revealed a stuck brine
tank float switch.
5.4 Internal Audits
Dr. Jane McLamarrah of ARCADIS performed an internal technical systems audit at the
demonstration site on August 17, 2000. Results from the audit were reported to the ARCADIS
Project Manager in an audit report, which is included in Appendix B. An internal data quality
assessment was done on the raw field and laboratory data. QA/QC data supplied by the field
crew and contract laboratories was reviewed and data quality indicators including accuracy and
precision were calculated. Calibration curves were reviewed and calculation verified for at least
10 percent of all the analytical data. Laura Beach, ARCADIS QA Manager/Durham Office,
performed this assessment.
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Chapter 6
References
Berthouex, P. M. and L. C. Brown. 1994. Statistics for Environmental Engineers. CRC Press,
Lewis Publishers p. 129.
DiGiano, F.A., W.J. Weber, Jr. 1996. Process Dynamics in Environmental Systems. First
Edition. John Wiley & Sons, Inc.
Levenspiel, O. 1972. Chemical Reaction Engineering. Second Edition. John Wiley & Sons,
Inc.
NSF International. 1999. Protocol for Equipment Verification Testing for Inactivation of
Microbiological Contaminants. August 1999.
NSF International. 2001. Environmental Technology Verification Report, ClorTec T-12.
NSF International. 2000. Field Operations Document. EPA/NSF Environmental Technology
Verification Test of the OXI-2B On-site Hypochlorite Generator at SJWD Water District
Drinking Water Plant, Lyman, South Carolina.
APHA, AWWA and WPCF (1999). Standard Methods for the Evaluation of Water and
Wastewater, 20th Edition, Washington, D.C.
USEPA. 1989. Guidance Manual for Compliance with the Filtration and Disinfection
Requirements of the Surface Water Treatment Rule for Public Water Systems using Surface
Water Sources. Appendix C. Science and Technology Branch.
White, Geo. Clifford. 1992. Handbook of Chlorination, 3rd edition. Van Nostrand Reinhold,
New York, NY.
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