xvEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-80-049
March 1980
Residual Oxidants
Removal from Coastal
Power Plant Cooling
System Discharges:
Field Evaluation of SC>2
Addition System
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-80-049
March 1980
Residual Oxidants Removal
from Coastal Power Plant
Cooling System Discharges:
Field Evaluation of
SO2 Addition System
by
K. Scheyer and G. Houser
TRW, Inc.
One Space Park
Redondo Beach, California 90278
Contract No. 68-02-2613
Task No. 23
Program Element No. INE624A
EPA Project Officer: Julian W. Jones
Industrial Environmental Research Laboratory
Office of Environmental Engineering and Technology
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
This study was conducted to evaluate the performance of a dechlorination
system which uses sulfur dioxide to remove residual oxidants from chlorinated
sea water in a power plant cooling system. Effectiveness of removal and deve-
lopment of average and maximum achievable levels of dechlorination were to be
developed. A field sampling and analysis program at Pacific Gas and Electric's
Potrero power plant, located in San Francisco, was developed to provide the
necessary data. Samples of unchlorinated, chlorinated, and dechlorinated cool-
ing water were obtained at the plant. These samples were collected during 28
sampling periods -- 14 at flood tide and 14 at ebb tide conditions -- and ana-
lyzed for several chemical and physical constituents. An amperometric titra-
tor was used for field analysis of total oxidant residual (TOR) and free oxi-
dant residual (FOR). Analytical results, along with plant operating data and
laboratory experiments, provided the information used to evaluate the dechlor-
ination system. Major conclusions which can be derived from the data are as
follows: (1) the dechlorination system studied showed effective removal of
residual oxidants from chlorinated sea water used in the power plant cooling
system; (2) the dechlorination system proved reliable as no measurable oxi-
dant residual was found at the effluent outfall; and (3) due to the effective-
ness of the dechlorination system in removing all measurable oxidant residual,
average and maximum levels of dechlorination cannot be determined.
ii
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CONTENTS
Abstract ii
Figures iv
Tables iv
List of Abbreviations and Symbols v
1. Introduction 1
2. Conclusions and Recommendations 3
3. Description of the Potrero Power Plant 4
General plant layout and operating parameters . . 4
4. Sampling Equipment and Methodology 8
Sampling apparatus 8
Sampling system check-out 11
Sampling and methodology and rationale 11
5. Analysis Methodologies 14
Field analysis 14
Laboratory analysis 16
6. Analytical Results and Associated Plant Operating
Parameters 18
Data collected 18
Analytical results 18
7. Laboratory Evaluation of Temperature Effect on
Dechlorination Efficiency 25
References 27
Bibliography 28
Appendices
A. Evaluation of the effect of sample collection on
volatile organic compounds 29
B. Selection of ebb and flood tide sampling conditions. . 30
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FIGURES
Number Page
1 Plot plan diagram of Potrero power plant 5
2 Vacuum sampling system 9
3 Chlorinated and unchlorinated sample collection system. . . 10
TABLES
Number Page
1 Constituents Measured and Analytical Methods, Accuracies
and Detection Limits 17
2 Selected Sampling Tides and Plant Operating Parameters 19
3 Chlorinated Condenser Outlet Field Data 20
4 Dechlorinated Effluent Field Data 21
5 Unchlorinated Condenser Outlet Field Data 22
6 Laboratory Analytical Data 23
7 Temperature Effect vs Dechlorination Efficiency 26
IV
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LIST OF ABBREVIATIONS AND SYMBOLS
PG&E - Pacific Gas and Electric Company
TOR - Total Oxidant Residual
FOR - Free Oxidant Residual
COR - Combined Oxidant Residual
S02 - Sulfur Dioxide
BOD - Biological Oxygen Demand
TOC - Total Organic Carbon
D.O. - Dissolved Oxygen
MW - Megawatt
DC - Dechlorinated Sample
C - Chlorinated Sample
RW - Unchlorinated Sample
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SECTION 1
INTRODUCTION
Chlorination of cooling waters is the most successful and widely ap-
plied method presently used to control biofouling of condensers in power
plant cooling circuits. Recently, some power plant chlorination practices
have been revised to include dechlorination of cooling water prior to dis-
charge into surface waters. Dechlorination results in the removal of chlor-
ine residuals, and may have a significant impact on future chlorination
practices.
Current chlorination practices require the addition of a specified
quantity of chlorine at the cooling water intake. The chlorine dosage is
presently limited by the residual chlorine (residual oxidant in the case
of sea water) that is found downstream of the cooling cycle in the outfall.
Federal standards require that the residual chlorine/oxidant level cannot
exceed 0.5 mg/1 at any time and cannot exceed an average of 0.2 mg/1 for a
period of two hours in any day from any one unit (1). Many state and local
standards are more stringent than the federal standards. Dechlorination
prior to discharge of chlorinated cooling water can assist plants in con-
forming with the more stringent standards.
This report was prepared under the direction of EPA to provide valu-
able data necessary for evaluating the performance of a dechlorination sys-
tem designed to remove residual oxidants from chlorinated sea water. Evalu-
ation of dechlorination practices was accomplished by development of this
program consisting of sample collection for unchlorinated, chlorinated and
dechlorinated streams and performance of physical and chemical analysis
for relevant parameters. Analysis was performed for several constituents
in each sample immediately after this sampling period. Analyses results
from 28 sample periods, for the three streams mentioned above, along with
plant operating data and laboratory experiments, provided the information
used to evaluate the dechlorination system.
-------
Pacific Gas and Electric's Potrero power plant (located in San
Francisco, California) is currently operating a full scale sea water de-
chlorination system on a daily basis and was thus selected for this field
sampling study.
-------
SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
This section highlights the conclusions reached in this study and
presents recommendations for further research.
CONCLUSIONS
Analytical data obtained during the course of this study show
that dechlorination is a reliable and effective method of remov-
ing residual oxidants from chlorinated sea water used in power
plant cooling circuits. Specifically, sulfur dioxide was shown
to be effective in removing residual oxidants at levels near
0.2 mg/1 from chlorinated sea water at PG&E's Potrero power plant.
Results of amperometric titration showed no measureable oxidant
residual at the outfall during the 28 sampling periods.
Based on residual oxidant measurements, it is concluded that
there is no tidal effect on dechlorination at the Potrero power
plant.
The effects of organic loading could not be determined at the
Potrero power plant because of extremely low organic loading as
indicated by BOD and TOC measurements.
Results obtained from laboratory tests suggest that dechlorination
efficiencies tend to increase with increasing temperature. How-
ever, it appears that this increase in efficiency can be attri-
buted to an increase of TOR decay, in the time period between
chlorination and dechlorination, and not due to the dechlorination
reaction.
Due to the effectiveness of the dechlorination system in removing
all measurable oxidant residual, average and maximum levels of
dechlorination cannot be. determined.
RECOMMENDATIONS
Continued evaluation of dechlorination on sea water cooling cir-
cuits containing higher levels of organics is required in order
to determine the effect of organics on dechlorination.
Evaluate dechlorination at higher chlorine dosages to determine
the effective limits of dechlorination.
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SECTION 3
DESCRIPTION OF THE POTRERO POWER PLANT
Information presented in the following discussion pertains to the
portion of the Potrero power plant associated with the cooling water cir-
cuit, chlorination and dechlorination systems. Plant operating parameters
for these systems are also presented.
GENERAL PLANT LAYOUT AND OPERATING PARAMETERS
The Potrero power plant is located on San Francisco Bay approximately
7 miles southeast of the Golden Gate Bridge. The power plant consists of
three units; however, for thissstudy only unit #3 was evaluated. Gross
generating capacity of Unit #3 is 210 MW with a maximum cooling water flow
rate of 8.74 m3/sec. (140,000 gpm) (2).
A plot plan diagram of Unit #3 is shown in Figure 1. The diagram
shows the locations of the once through cooling water circuit, turbine
generator building, chlorination system and dechlorination system. Cool-
ing water withdrawn from the bay passes through a bar rack and travelling
screens to two circulating water pumps which supply cooling water to the
condenser. The condenser consists of two separate unit halves, each sup-
plied by a separate circulating water pump. Heat exchange occurs in the
condensers, consisting of 22.2 mm (7/8 in) diameter aluminum-brass or
copper nickel alloy tubes (2). Immediately downstream of the condenser
the heated water from both halves combine and at this point is dechlori-
nated. Following dechlorination, the water travels to the outfall struc-
ture and is subsequently discharged into the bay.
Chlorination System
Chlorine is injected continuously for 30 minutes, twice daily, into
each half of the cooling water circuit just upstream of the circulating
water pumps. Tunnel #1 (see Figure 1) is chlorinated at 0900 and 1500
hours, followed immediately by chlorination of Tunnel #2 at 0930 and 1530
hours.
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SAN FRANCISCO BAY
SO, Solution 4»<
"line "- : *
Outfall
Sampling Effluent
Location Outfall
"/
i, n
Mixing/Dechlorination' ! .1
Box ^ ir
Dechlorination
Building
>. r"- 1
Ni *
iS^j
LV-^-M
Unit No. 3
Turbine Generator
Building
Access
Roads'
:*'-0
Cooling Water
Tunnels
^^^n Lvsaj^_M
/^ 7\
Condensor Outlet
Sampling Locations
Condensor Inlet
Tunnel
-5!'
1
-Tunnel #2
Figure 1. Plot plan diagram of the Potrero power plant.
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At the Potrero plant compressed liquid chlorine is withdrawn from
storage cylinders, evaporated and injected into a small stream of sea water,
producing a concentrated chlorine solution. During the sampling program the
concentration of this solution on the average was 130 mg/1. This solution is
injected into the intake cooling water immediately upstream of each of the
circulating water pumps.
Oxidant residuals are normally adjusted between 0.3 and 0.4 ppm of
total oxidant residual (TOR) at the condenser inlet. This adjustment is
normally performed after an extended non-use period or after repair of mal-
functions in the chlorination system. The adjustment is made by measuring
TOR at the condenser inlet while manually adjusting the chlorine dosage to
produce the desired TOR. The approximate chlorine feed rate associated
with the desired TOR (determined by PG&E) is 9.5 Kg/hr (20.8 Ib/hr).
When sea water is chlorinated the principle equilibrium species formed
are brominated compounds analogous to chlorinated species produced in fresh
water. In the pH range from 6 to 8 these brominated species are HOBr, OBR~,
NBr3, NHBr2 and NH2Br (9).
Dechlorination System
The dechlorination system employs the same principle of operation as
the chlorination system with two main differences. Sulfur dioxide (S02)
is used as the dechlorinating compound and the point of addition of the
concentrated S02 solution is at the mixing box located within the conden-
ser cooling water discharge.
The dechlorination system is operated for an hour twice daily con-
current with chlorination. The dechlorinator removes total oxidant resi-
dual from mixed cooling waters of both halves of the condenser, although
for the first 30 minutes only Tunnel #1 is chlorinated and the following
30 minutes only Tunnel #2 is chlorinated.
S02 is withdrawn from storage cylinders, evaporated and injected
into a small stream of sea water producing an S02 solution. The average
concentration of the S02 solution during the sampling program was 500 mg/1.
This solution is piped to the mixing box where it is dispersed through
seven diffusers into the combined chlorinated and unchlorinated streams.
-------
Optimization of the dechlorination system is performed when residual oxi-
dant is measured at the outfall or when the system is started up after a
period of down time. Optimization is performed (by PG&E) in the following
manner:
S02 feed rate is manually increased during chlorination while
holding the chlorine feed rate constant.
Total oxidant residual is measured at the outfall as the S0?
feed rate is increased.
S0? feed rate is increased until there is no measurable TOR at
the outfall.
S02 feed rate is then increased by 50 Ib S02/24 hr as a safety
factor.
The S02 feed rate determined by PG&E is 7.6 Kg/hr (16.7 Ib/hr) for a
chlorine feed rate of 9.5 Kg/hr (20.8 Ib/hr).
When sulfur dioxide is added to the chlorinated cooling water it re-
acts instantaneously with the brominated species according to following
equations (10):
HOBr *~ H$0 + HBr
S02
NH2 Br + H2S03 + H20 -^ NH4HS04 + HBr
NHBr2 + H2S03 + H20 -+- NH3BrHS04 + HBr
NBr3 + H2S03 + H20 +- NH2Br2HS04 + HBr
Sampling Points
Sampling locations are shown in Figure 1. Chlorinated and unchlori-
nated cooling waters were sampled at the outlet of the condenser prior to
combination of the two streams in the mixing box. Both sampling points
were equipped with sampling taps; however, both were under a vacuum of
about 25.4 cm (10 in) of mercury. The sampling location for dechlorinated
cooling water was a manhole situated downstream of the dechlorinator at the
outfall structure. The sampling line was submerged in the dechlorinated
effluent by using a weighted strainer.
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SECTION 4
SAMPLING EQUIPMENT AND METHODOLOGY
The following discussion details sampling equipment and methods em-
ployed to collect samples of unchlorinated, chlorinated and dechlorinated
samples of sea water from the power plant's cooling circuit. Included
is the special sampling method used to collect samples for oxidant residual
analysis and tests performed to determine if the sampling collection sys-
tem had any effect on volatile organic compounds or dissolved oxygen.
SAMPLING APPARATUS
The sampling system employed in this study was designed to conform
with the following design criteria:
t System must be capable of overcoming vacuum at condenser outlet
sampling points and 15 feet of static head from the dehclorinated
sampling point.
Collected sample shall be shielded from sun light in order to
avoid rapid decay of oxidant residuals.
t Each sample obtained during a single sampling period must be
representative of the same once through cooling water whether
it be unchlorinated, chlorinated and dechlorinated water.
The sampling system designed and constructed is shown in Figures 2
and 3. The system basically consists of a vacuum pump, vacuum sample col-
lection tank, vacuum tank top with sampling control valve, and sample
lines. This system was constructed in triplicate enabling identical sys-
tems to be utilized at each of the three sampling locations. The only
difference between the three sampling systems was that the condenser
chlorinated and unchlorinated sampling systems were attached to the ex-
isting taps on the condenser outlet; while the dechlorinated sampling sys-
tem was connected to a weighted sampling strainer at the end of the sample
line which was submerged in the dechlorinated effluent below the manhole.
8
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Connected to
Vacuum Pump
Sample Control
Valve
Vacuum Tank Top
Coated Polycarbonate,
Vacuum Tank
Sample Line
Connected to Sample
Taps on Condenser
Outlet or Strainer
for Effluent Sampling
Nalgene Container for
^Residual Oxidant Sample
Acquisition
Composite Sample
Figure 2, Vacuum sampling system
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Figure 3. Chlorinated and unchlprinated sampling collection systems
10
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SAMPLING SYSTEM CHECK-OUT
Following construction of the units, tests were performed to study
the effect of samples, containing volatile organic compounds and dissolved
oxygen, obtained with the vacuum system. In the case of volatile organics
a known volume of sea water was spiked with known volumes of haloforms.
The spiked solution was evacuated into the field sampling system using the
vacuum pump, thus simulating field conditions. After collection, both
spiked samples (before and after collection) were analyzed for volatile
organic compounds. Results showed that no significant changes in organic
concentrations was observed utilizing the vacuum sampling system (see
Appendix A for presentation of the detailed results).
Dissolved oxygen levels of tap water were measured before and after
collection with the field sampling apparatus, as discussed previously for
volatile organics. Results showed that, on the average, oxygen levels
declined approximately 0.25 ppm during the sampling period. This value
is not considered excessive because the reported precision limit for the
dissolved oxygen instrument is +_ 0.1 ppm with a measurement accuracy of
± 0.2 ppm (3).
SAMPLING AND METHODOLOGY AND RATIONALE
The program consisted of 28 sampling periods, 14 at ebb tide and 14
at flood tide conditions. (Refer to Appendix B for a detailed presenta-
tion of tide conditions existing at each sampling period). During each
sampling period samples were simultaneously obtained for chlorinated, un-
chlorinated and dechlorinated cooling water. Consistent sampling proce-
dures were maintained throughout the program with the exception of the
first three tests which differed from the remaining 25 tests in sample ac-
quisition for residual oxidant determination. Results of residual oxi-
dant analysis in the first three tests were found to be unexpectedly low.
This resulted from residual oxidant decay during the time period from
sample collection to residual oxidant analysis. Therefore, a change in
the sampling procedure was necessary to minimize sample degradation,
thereby insuring a greater degree of accuracy. This objective was accom-
plished by the addition of a one liter nalgene container into each sampl-
ing system as shown in Figure 2. The nalgene container permitted recovery
11
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of the most recent sample acquired to be analyzed for oxidant residuals.
In the first three tests the composite sample was analyzed to determine
residual oxidants. During the following 25 tests samples collected in the
nalgene container containing the most recent sample acquired (not the com-
posite) were analyzed to determine residual oxidants. The composite sample
was used for all other analyses including volatile organics analyses.
The following sampling procedure was used during sampling -periods 4
through 28. Procedures for periods 1, 2 and 3 were slightly different
for oxidant residual sampling as mentioned above. (Times referenced to
the start of the chlorination cycles.)
(1) Prerinse of sampling system - at 10 minutes the sampling system
was started at all locations. After a small quantity of liquid
was collected the system was stopped and the sample discarded.
All sample lines were drained of any liquid.
(2) At 15 minutes sampling was initiated at all locations.
(3) At 16-17 minutes the dechlorinated sampling system was turned
off, the nalgene container removed, replaced by another nalgene
container and the system was restarted. Immediate titration for
TOR and FOR was performed. (TOR = Total Organic Residual;
FOR = Free Organic Residual; FOR analysis was performed only
if there is a measurable TOR).
(4) At 19-20 minutes procedure 3 was performed on the'chlorinated
sample and the system was restarted.
(5) At 24 minutes procedure 3 was performed on the dechlorinated
sample, except the nalgene container was not replaced and the
system was not restarted.
(6) At 25 minutes the chlorinated and unchlorinated sampling systems
were shut down. The nalgene container from the chlorinated
sampling'system was removed and analyzed immediately for TOR and
FOR. Also a portion of the unchlorinated sample was analyzed for
TOR.
The designated sampling times and procedures stated in the sampling
procedure were selected for the following reasons:
t Prerinse of the sampling system was required to prevent contami-
nation from liquids left in the lines and containers from previous
sample periods.
Initiation of the sample collection was initiated at 15 minutes
to ensure the system had established equilibrium and to allow
time for prerinse of all systems.
12
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Sample collection period of 10 minutes was to allow adequate time
to collect and analyze chlorinated and dechlorinated samples for
residual oxidants.
t Sampling was concluded at 25 minutes to ensure no overlap occurs
between chlorination cycles of Tunnel No. 1 and Tunnel No. 2 (over-
lap would cause contamination of unchlorinated cooling water with
chlorinated cooling water and vice versa).
13
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SECTION 5
ANALYSIS METHODOLOGIES
Analysis of the cooling water samples included both field and labora-
tory analysis. The following is a summary of the analyses performed, analy-
tical methods used, measurement accuracies and detection limits. A detailed
discussion relative to the accuracy of residual oxidant analysis and adjust-
ments made to increase the accuracy is also presented.
FIELD ANALYSIS
Immediate on-site analysis was required for the following unstable
parameters: TOR, FOR, pH, dissolved oxygen (D.O.) and temperature.
TOR and FOR were determined using the Fisher and Porter portable amper-
ometric titrator (model 17T1010). Measurment accuracy of the amperometric
titration is +_ 0.01 ppm-of oxidant residual with a minimum detection level
of 0.03 ppm (4,5,6,7).
Oxidant residual analysis was performed twice on each dechlorinated
and chlorinated sample. Only one analysis was performed on the unchlori-
nated sample to check for background oxidant residual. During the sampl-
ing period two separate analyses of oxidant residual were performed on both
dechlorinated and chlorinated samples. The average of the two analyses are
reported in the results. During each analysis period (twice per sampling
period) both TOR's and FOR's were measured. One measurement immediately
following the other. However, an error is inherent in this procedure due
to residual oxidant decay. For example, if TOR is performed before FOR,
a time lapse of approximately 2.0 minutes occurs before the second analy-
sis (FOR) can be completed. Therefore, the FOR measurement is not strictly
comparable with the TOR measurement because during the 2 minutes the FOR
level has decreased due to oxidant residual decay. To facilitate a valid
comparison of TOR with FOR the value of the second parameter measured re-
quires adjustment to the same analysis time frame as the first parameter.
In the above example, measured FOR values require time frame adjustment to
compensate for decay and allow a valid comparison with TOR measurements.
14
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FOR and TOR Time Frame Adjustments
A procedure for measuring TOR and FOR for adjustment of values between
the second and the first analysis time frame results was developed. This
procedure consisted of two similar measurement techniques identified as "A"
and "B". Technique "A" is the measurement of TOR, followed immediately by
FOR measurement, followed immediately by another TOR measurement for a
single sample. Technique "B" differs from "A" by the order of measurement,
first measurement of FOR, followed immediately by a TOR measurement, follow-
ed immediately by another FOR measurement. Differences of the first and
third measurements (technique "A" difference of TOR'S, technique "B" differ-
ence of FOR's) were computed and averaged for a few sets of samples. One-
half of the average value of the first and third analysis results is used
to adjust second analysis results to the first analysis time frame. For
example, one-half of the average difference of the first and third measure-
ments (TOR's) of all the samples measured in technique "A" was added to TOR
values for those analyses periods where FOR was measured first and TOR mea-
surement second (technique "B"). Similarly, for analysis periods when TOR
was measured first and FOR second, an average computed rate of decay value
is added to the FOR value to obtain an adjusted value. This method of ad-
justment was used on those values noted in the results and has two main
disadvantages that should be noted. The method assumes a linear decay rate
of the residual oxidants because of a lack of available data pertaining to
decay rates at the low levels of residual oxidant encountered in chlorinated
sea water. However, due to the short duration of the analysis period (less
than 5 minutes) for completion of all three analyses (as described by tech-
niques "A" and "B"), linearity appears to be a valid assumption. The other
disadvantage is the adjustment creates a larger uncertainty in the calcu-
lated values than for a measured oxidant residual value. However, this
time adjustment of measured values is required to facilitate a valid com-
parison of results.
Based on the measurement accuracy of +_0.01 ppm and the computed stand-
ard deviation of 0.01 ppm for the sets of results used to adjust FOR and
TOR values, the accuracy of the adjusted FOR's and TOR's is +0.03 ppm.
The accuracy of COR's is +0.04 ppm.
15
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Dissolved Oxygen. pH and Temperature
Dissolved oxygen, pH and temperature were measured at the end of the
sampling period for all samples. The dissolved oxygen was measured using
a portable Chemtrix oxygen meter (model 5946-10) with an accuracy of +. 0.2
ppm (3). pH was measured with an Analytical Measurements Inc., portable
pH meter (model No. 107). Temperature was measured with a mercury thermo-
meter.
LABORATORY ANALYSIS
Two samples of the cooling water from each sampling location were
collected for laboratory analysis. The samples, one preserved with sulfur-
ic acid and the other unpreserved.were stored in an ice chest for daily
pickup and subsequent analysis. Table 1 presents the constituents measur-
ed and analytical methods used, including accuracies and detection limits
of each method.
16
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TABLE 1. CONSTITUENTS MEASURED AND ANALYTICAL
METHODS, ACCURACIES AND DETECTION LIMITS
Constituent
Measured
Organic Nitrogen (as N)
Ammonia Nitrogen (as N)
Total Organic Carbon
Biochemical Oxygen
Demand
Bromide
Chloride
Analytical Method Measurement
Accuracy(S)*
Kjeldahl digestion
Distillation and
Nesslerization
Infrared Analyzer
Incubation followed
by dissolved oxygen
determination
Specific ion electrode
Specific ion electrode
0.01
0.05
1
3
0.1
1
Detection
Limit (3)
+ 0.03
+ 0.03
+ 1
+ 1
**
**
* 95% Confidence Limit
** Insufficient data were generated to statistically calculate a meaning-
ful standard deviation. However precision was determined to be +_ 1.5%
for duplication of chlorides with a 101% recovery of spike and +_ 8%
for duplication of bromide with a 91% recovery of spike.
17
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SECTION 6
ANALYTICAL RESULTS AND ASSOCIATED PLANT OPERATING
PARAMETERS
Data collected and analytical results relating to each of the 28 tests
are presented and discussed in this section.
DATA COLLECTED
During each field test the plant operating data presented in Table 2
were recorded. The reported chlorine and sulfur dioxide feed rates are of
limited accuracy due to difficulties in reading the gas flow meters. This
difficulty resulted from erratic fluctuation of the flowmeter float. Cool-
ing water flow rates reported were based on the original design flow rate
for the circulating water pumps and are also of limited accuracy. Sampling
dates, times and tide conditions are also shown in Table 2. These uncer-
tainties affect the chlorine dosage calculated and presented in Table 3 also.
ANALYTICAL RESULTS
The results of the field testing and the associated laboratory analyti-
cal results are presented in Tables 3, 4, 5 and 6.
Oxidant residuals measured at the chlorinated condenser outlet ranged
from 0.122 to 0.339 mg/1 TOR, 0.062 to 0.273 mg/1 FOR and 0.012 to 0.135
mg/1 COR*. Oxidant residuals of dechlorinated effluent and unchlorinated
condenser outlet samples were below the detection limit of 0.03 mg/1. There-
fore, results for FOR and COR are not presented.
pH varied from 7.0 to 7.7 with no significant trends for the chlori-
nated condenser outlet, dechlorinated and unchlorinated condenser outlet
samples. Dissolved oxygen varied from 3.4 to 7.0 mg/1 without any distin-
guishable trends between the three sampling locations.
* jests 1-3 not included because of different sampling and analysis proce-
dure as discussed in Section 4.0.
18
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TABLE 2. SELECTED SAMPLING TIDES AND CORRESPONDING PLANT
OPERATING PARAMETERS
Test No,
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Date
9/5
9/5
9/6
9/6
9/7
9/11
9/11
9/12
9/12
9/13
9/13
9/14
9/14
9/15
9/15
9/16
9/16
9/17
9/17
9/18
9/18
9/19
9/19
9/20
9/20
9/21
9/21
9/22
Time
0900
1500
0900
1500
1500
0900
1530
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
Tide
Condition
Flood
Ebb
Flood
Ebb
Ebb
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Load
MM
173
133
173
174
173
53
60
143
140
175
180
178
180
180
180
180
180
180
180
180
180
180
180
180
180
180
180
180
Cooling Water
Flowrate (m3/sec)
Tunnel #1 Tunnel #2
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3,1
3.1
3.1
3,1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
3.1
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2,8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
2.8
Condenser
Inlet
°C
17
16
16
16
16
16
16
17
17
18
17
17
18
18
18
18
18
17
17
17
18
18
17
16
16
17
17
17
Temperature
Outlet
°C
28
25
27
25
26
21
26
27
27
29
29
30
27
27
27
27
27
27
27
27
27
26
26
26
26
27
27
27
Chlorine Feed
Rate
(Kg/hr)
9.5
9.1
9.5
9.3
8.0
9.3
9.0
9.0
8.9
8.9
8.9
9.0
9.7
9.7
9.7
9.7
9.8
10.0
9.8
9.5
9.5
9.1
9.5
4.7
9.5
9.0
9.0
9.3
Sulfur Dioxide
Feed Rate
(Kg/hr)
9.0
7.9
7.7
7.7
7.7
7.4
7.7
7.9
7.4
7.9
7.7
8.9
7.1
7.7
6.8
7.7
6.8
7.6
7.1
7.6
7.6
7.2
7.6
7.6
7.1
7.1
6.9
b.6
-------
TABLE 3. CHLORINATED CONDENSER OUTLET FIELD DATA
Test No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Chlorine
Dose *
(mg/1)
0.85
0.82
0.85
0.83
0.72
0.83
0.81
0.81
0.80
0.80
0.80
0.81
0.87
0.87
0.87
0.87
0.88
0.89
0.88
0.85
0.85
0.82
0.85
0.42
0.85
0.81
0.81
0.83
TQR
(mg/1 )
0.052
0.027
0.093
0.200
0.269
0.178
0.122
0.168
0.213
0.217
0.206
0.225
0.243
0.265
0.315
0.281
0.320
0.339
0.331
0.277
0.289
0.259
0.304
0.140
0.306
0.270
0.256
0.322
FOR
(mg/1)
<0.03
<0.03
0.053
0.118
0.221
0.164
0.062
0.106
0.126
0.152
0.146
0.158
0.176
0.222
0.232
0.194
0.234
0.267
0.263
0.246
0.212
0.205
0.241
0.104
0.259
0.227
0.233
0.273
COR**
(mg/1)
0.052
0.027
0.040
0.082
0.077
0.012
0.091
0.135
0.087
0.065
0.060
0.067
0.067
0.043
0.083
0.087
0.086
0.072
0.064
0.031
0.077
0.054
0.063
0.036
0.047
0.043
0.023
0.049
PH
7.4
7.5
7.4
7.1
7.4
7.3
7.4
7.4
7.4
7.4
7.3
7.6
7.3
7.6
7.5
7.6
7.6
7.4
7.0
7.6
7.6
7.5
7.6
7.7
7.7
7.7
7.7
7.7
D.O.
(mg/1)
3.9
3.7
4.9
4.7
5.4
5.0
5.8
5.5
5.4
5.4
5.4
7.0
5.4
5.5
5.1
5.2
4.8
5.1
5.0
5.3
5.4
5.0
5.0
5.3
5.4
5.0
5.4
5.2
Temperature
(°C)
27.0
27.0
28.0
28.0
28.0
24.0
25.0
27.0
29.5
28.0
28.5
28.0
28.0
27.0
27.0
28.0
28.0
28.0
27.0
27.0
27.0
27.5
26.0
26.0
26.0
27.0
27.0
27.8
* Calculated based on chlorine and cooling water flow rates
** Calculated: TOR - FOR = COR
20
-------
TABLE 4. DECHLORINATED EFFLUENT FIELD DATA
Test No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
TOR
(mg/1 )
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0,03
<0.03
pH
7.4
7.6
7.4
7.4
7.4
7.3
7.4
7.4
7.4
7.4
7.4
7.4
7.3
7.4
7.5
7.6
7.6
7.4
7.7
7.7
7.6
7.4
7.7
7.6
7.7
7.6
7.7
7.7
D.O.
(mg/1 )
3.7
3.9
4.7
5.8
5.2
4.8
5.3
5.5
5.1
5.4
5.0
5.4
5.5
4.9
5.1
5.1
5.4
5.5
5.4
5.6
5.5
5.2
5.4
5.4
5.6
5.4
4.9
5.6
Temperature
(°C)
27.0
27.0
28.0
28.0
27.0
24.0
25.0
27.0
28.5
27.0
28.0
27.5
27.5
27.0
27.0
28.5
28.5
27.0
27.0
27.0
27.0
27.0
26.0
26.0
26.0
26.0
27.0
27.8
21
-------
TABLE 5. UNCHLORINATED CONDENSER OUTLET FIELD DATA
Test No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
TOR
(rag/1 )
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
<0.03
pH
7.6
7.3
7.5
7.4
7.2
7.4
7.4
7.4
7.4
7.4
7.4
7.0
7.4
7.5
7.5
7.7
7.7
7.4
7.7
7.7
7.6
7.6
7.7
7.7
7.7
7.6
7.7
7.7
D.O.
(mg/1 }
3.5
3.4
5.2
5.4
5.5
5.6
5.3
5.9
5.9
5.7
6.0
5.8
5.8
5.4
5.4
5.3
5.7
5.5
5.5
5.5
5.8
5.4
5.7
5.5
5.6
5.4
5.8
5.8
Temperature
(°C)
26.0
27.0
28.0
28.0
27.0
24.0
25.0
27.0
29.5
28.0
28.5
28.0
28.0
27.0
27.0
28.0
28.0
28.0
27.0
27.0
27.0
27.0
27.0
26.0
26.0
27.0
27.0
27.8
22
-------
TABLE 6. LABORATORY ANALYTICAL DATA
ro
GO
Test No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
C*
2
2
1
<1
<1
1
1
1
1
2
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
BOO
mg/i
DC+
2
1
1
1
1
1
2
1
2
1
1
1
1
2
2
2
1
1
1
<1
1
1
2
1
1
1
2
2
Rlprf C
2
2
1
1
1
2
1
3
1
1
2
1
1
1
1
1
2
1
1
1
1
1
1
2
1
1
1
1
3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
3
4
<3
<3
<3
<3
3
3
TOC
mg/i
DC
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
3
4
<3
<3
<3
<3
3
<3
RW
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
<3
3
3
<3
<3
<3
<3
3
3
Ammonia Nitrogen
mg/i
C DC RW
0.28
0.08
0.12
0.06
0.07
0.08
0.08
0.09
0.08
0.21
0.09
0.08
0.10
0.07
0.06
0.07
0.08
0.06
0.08
0.07
0.11
0.07
0.06
0.09
0.05
0.07
0.08
0.06
0.06
0.11
0,13
0.07
0.10
0.10
0.09
0.09
0.10
0.15
0.09
0.07
0.10
0.09
0.07
0.06
0.07
0.07
0.08
0.08
0.09
0.08
0.07
0.08
0.05
0.08
0.07
0.13
0.13
0.11
0.14
0.08
0.09
0.11
0.09
0.09
0.09
0.14
0.10
0,08
0.09
0.07
0.07
0.08
0.08
0.11
0.09
0.08
0.09
0.09
0.07
0.08
0.06
0.08
0.08
0,07
Organic Nitrogen
mg/i
C DC RW
0.54
0.29
0.28
0.25
0.26
0.48
0.32
0.37
0.34
0.26
0.36
0.34
0.58
0.29
0,37
0,27
0.24
0.25
0.33
0.35
0.30
0.41
0.39
0.33
0.35
0,31
0.32-
0.34
0.35
0.25
0,34
0.30
0.24
0.19
0.32
0.30
0.32
o.2r
0.27
0.32
0,29
0.29
0.31
0.25
0,10
0.30
0.37
0.36
0.27
0.57
0.34
0.30
0.32
0.34
0.29
0.25
0.25
0.30
0.48
0.31
0,23
0.33
0.40
0.26
0.30
0.08
0.36
0,30
0.37
0.30
0,35
0.24
0.22
0.28
0.32
0.32
0.24
0.34
0.34
0.31
0.31
0.27
0.29
0.29
C
86
50
81
71
79
59
64
73
73
73
49
62
62
68
64
73
66
62
63
65
63
54
57
90
63
88
53
86
Bromide
mg/i
DC RW
87
50
61
73
77
77
64
81
74
70
4-9
61
60
65
65
68
69
61
63
65
60
60
57
88
63
88
__**
82
84
50
59
71
70
71
56
64
77
67
49
76
49
67
65
64
75
76
64
52
65
72
60
65
67
77
68
35
Chloride
mg/i
C DC
17G10
17210
17310
17560
17560
17360
17360
17510
17460
17410
17260
17210
17310
17560
17360
17310
17510
17260
17210
17260
17410
17360
17310
17310
17310
17360
17460
17610
17360
17210
17260
17560
17610
17210
17610
17310
17360
17260
17310
17210
17310
17410
17310
17410
17410
17460
17260
17310
17460
17360
17310
17460
17610
17360
17360
17510
RW
17360
17310
17310
17410
17660
17460
17410
17610
17410
17360
17210
17310
17210
17460
17510
17310
17610
17460
17310
17310
17410
17110
17460
17460
17710
17410
17460
17510
C - Chlorinated condenser outlet
DC - Dechlorinated effluent
RW - Unchlorinated condenser outlet
- Unreliable results obtained
-------
BOD and TOC values were very low and there are no apparent trends for
results obtained from the three sampling locations. BOD values were gener-
ally 1-2 mg/1. A majority of the TOC values were below detection level. A
few TOC values of 3 and 4 mg/1 (near the detection limit) were reported.
Organic nitrogen values were generally about three times the ammonia
nitrogen values. Organic nitrogen values varied from 0.10 to 0.54 mg/1.
Ammonia nitrogen values varied from 0.04 to 0.28 mg/1. There does not ap-
pear to be any correlations between results for the three sampling locations.
Discussion of Results
PG&E's Potrero power plant dechlorination system was shown to operate
effectively for removal of oxidant residual from the cooling water system
based on results obtained by this program. As shown in Table 4, TOR values
were less than the 0.03 mg/1 detection limit of the amperometric titrator
for the 28 sampling periods. It should be noted that the unchlorinated
and chlorinated streams are combined before dechlorination occurs. There-
fore, the chlorinated stream is diluted by the unchlorinated stream, effec-
tively halving TOR levels reported for the chlorinated stream. For example
consider test number 18, TOR was 0.339 mg/1 (highest value reported during
the 28 sampling periods) in the chlorinated stream. However, due to the
dilution discussed above, the dechlorinator treated a combined stream with
a TOR concentration of only 0.18 mg/1.
Examination of the resiudal oxidant measurements with respect to tidal
conditions show no apparent correlation. However, due to the very slight
variations in cooling water characteristics, as indicated by the parameters
measured, a correlation between tidal conditions and residual oxidant levels
would not be expected.
It was not possible to determine the effects of organic loading on
dechlorination operation due to the very low organic loading of the cool-
ing water as indicated by the BOD and TOC values reported in Table 6.
24
-------
SECTION 7
LABORATORY EVALUATION OF TEMPERATURE EFFECT ON
DECHLORINATION EFFICIENCY
The objective of this task was to evaluate the effect of different
temperatures on the efficiency of dechlorination at conditions similar to
those existing at the Potrero power plant based on results obtained from
a laboratory jar test. During this evaluation chlorination levels, and
dechlorination reaction times selected were those prevailing at the Potrero
power plant. Also local bay water, collected near the cooling water in-
take, was used.
The evaluation procedure consisted of chlorination and dechlorination
at different temperatures ranging from 14°C to 35°C (60° to 95°F). During
the determination, power plant chlorination/dechlorination practices were
incorporated where viable. Total oxidant residuals were measured after
chlorination and after dechlorination by amperometric titration.
The following procedure was employed on several different samples at
various temperatures. One liter samples of sea water were chlorinated
with sodium hypochloride to attain oxidant levels of approximately 1.0 ppm.
Samples were analyzed for TOR, pH and D.O. after a period of time to allow
for reaction and stabilization. Following TOR measurement each sample was
dechlorinated with sodium thiosulfate (Na2S203). A sufficient quantity of
sodium thiosulfate was added to the sample to react with part "of the oxi-
dants present while leaving a measurable oxidant residual. This residual
oxidant was required to calculate removal efficiencies. Immediately after
dechlorination TOR was measured again.
Values of TOR after chlorination and after dechlorination, along with
removal efficiencies are presented in Table 7. Dissolved oxygen and pH
were measured at 5.6 ppm and 7.4, respectively, without a significant devia^
tion throughout the experiment.
25
-------
TABLE 7. TEMPERATURE EFFECT VS DECHLORINATION EFFICIENCY
Temp (°C)
14
18
21
25
25
34
36
TOR
after C12*
1.154
1.384
1.411
1.314
1.230
1.214
1.192
TOR
after DC12**
0.644
0.778
0.829
0.659
0.661
0.632
0.514
% TOR Removal
44.2
43.8
41.2
49.8
46.3
47.9
56.8
* C12 - Chlorination
** DC1? - Dechlorination
Removal efficiencies for TOR shown in Table 7 show a slight increas-
ing trend with higher temperatures. During laboratory testing it was ob-
served that as the temperature of the samples increased, the TOR remaining
in the samples after Chlorination decreased, even though chlorine dosage
was constant. Since equal quantities of dechlorination compound were added
to each sample, the increase in TOR removal efficiency is partially due to
the decrease in TOR before dechlorination as temperature increases. It can
not be concluded that the increase in TOR removal efficiency is entirely
associated with temperature effects on the dechlorination reaction.
26
-------
REFERENCES
(1) Federal Register, Vol. 39, No. 196, October 8, 1974.
(2) Pacific Gas and Electric Co. - Personal communication.
^ ir^rruction manual for portable Chemtrix oxygen meter, model
#5946-10.
(4) Instruction Bulletin for Model 17T1010 Amperometric Titrator
(Revision 1).
(5) Crecelius, E.A., et.al., "Errors in Determination of Residual
Oxidants in Chlorinated Sea Water", Battelle Northwest Labs.
(6) Carpenter, James A., et.al., "Errors in Determination of Residual
Oxidants in Chlorinated Sea Water", Environ. Sch. and Tech.,
11(10) pp 992-994, October 1972.
(7) Burge, B.L., "The Determination of the Amperometric Titration Method
for Total Residual Chlorine in Water-Forward Titration Procedure",
USEPA, Region V, Surveillance and Analysis Division, Michigan-Ohio
District Office.
(8) Fisher, Steven, Analytical Methods and Their Detection Limits,
October 18, 1979.
(9) Sung, R., et.al., "Assessment of the Effects of Chlorinated Sea Water
from Power Plants on Aquatic Organisms", EPA-600/7-78-221, November 1978.
(10) White, George C., "Chlorination and Dechlorination: A Scientific and
Practical Approach", Journal of American Water Works Association
60(5)540-561, 1968.
27
-------
BIBLIOGRAPHY
American Public Health Association, Standard Methods for the Examination
of Water and Wastewater. 14th ed., pp. 322-325, 1975. '
Bradbury, J.H. and A.N. Hambly, "An Investigation of Errors in the
Amperometnc and Starch Indicator Methods for the Titration of
Millinormal Solutions of Iodine and Thiosulfate" Australian J.
Sci. Res., Ser. A, 5 pp. 541-554.
Carpenter, James A., et al., "Errors in Determination of Residual Oxidants
in Chlorinated Sea Water11, Environ. Sch. and Tech., 11(10) pp. 992-
994, October 1972.
Carpenter, J.H., and C.A. Smith, "Reactions in Chlorinated Sea Water",
Water Chlorination Environmental Impact and Health Effects; Vol. 2,
editor R.J. Jolley, et al., Ann Arbor Science, 1978.
Crecelius, E.A., et al., "Errors in Determination of Residual Oxidants
in Chlorinated Sea Water", Battelle Northwest Labs.
Cole, S.A., Chlorination for the Control of Biofouling in Thermal Power
Plant Cooling Systems. Biofouling Control Proceedings Technology
and Ecological Effects. Marcel Dekker, Inc., 1977.
Federal Register, Vol. 39, No. 196, Ocotber 8, 1974.
Hergott, SI, et al., Power Plant Cooling Water Chlorination in Northern
California. University of California, Berkeley, UCB/SERL No. 77-3,
August 1977.
Hostgaard-Jensen, P., J. Klitgaard, K.M. Pedersen. Chlorine Decay in
Cooling Water and Discharge into Sea Water. Journal of the Water
Pollution Control Federation, pp. 1832-1841, August 1977.
Johnson, J.D., Analytical Problems in Chlorination of Saline Water.
Chesapeake Science, Vol. 18, No. 1, pp. 116-118.
Johnson, J.D. and G.W. Inman, The Effect of Ammonia Concentration on the
Chemistry of Chlorinated Sea Water. Water Chlorination, Vol. 2,
1978.
Marks, H.C. and Glass, J.R., "A New Method of Determining Residual Chlor-
ine", JAWWA Vol. 34, 1942, pp. 1227-1290.
Strickland & Parsons, A Practical Handbook of Sea Water Analysis, Fisheries
Research Board of Canada, Bulletin No. 167, 2nd. ed., 1972.
Sugarn, R., The Chemistry of Chlorine in Estuarine Waters. Unpub. thesis,
University of Maryland, College Park, pp. 702 (1977).
White, G.C., Handbook of Chlorination, Van Nostrand Reinhold Co., N.Y.
1972, pp. 264.
28
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APPENDIX A
EVALUATION OF THE EFFECT OF SAMPLE COLLECTION
ON VOLATILE ORGANIC COMPOUNDS
In order to determine if volatile organic compound measurements would be
significantly affected by collection with the designed field sampling system
(see Section 3.0 for details of the sampling system), the following experiment
was performed.
Solutions of haloforms, particularly chloroform, bromoform, bromodichlor-
omethane and chlorodibromomethane, at concentrations of 30 ppb, 10 ppb and 1
ppb, were prepared. Each solution was induced into the sampling system with
the vacuum pump used for field sampling. Samples of each solution (before
and after collection by sampling system) were analyzed by West Coast Technical
Service, Inc. using a gas chromatograph-mass spectrometer. Table A-l shows
haloform concentrations before and after collection. Samples labeled 30B, 10B
and IB represent samples after vacuum collection. The other three samples are
before vacuum collection. As shown in the table, no significant changes in or-
ganic concentrations were noticed.
TABLE A-l. VOLATILE ORGANIC LOSSES
Micrograms/Liter
Bromodichloro-
methane
TR = Trace amount detected
ND = Not detected
Chlorodibromo-
methane
.mp i e i
SOB
10B
IB
30 PPB
Haloforms
10 PPB
Haloforms
1 PPB
Haloforms
ON luruiui in
30
10
4
33
11
1
u i vsiiivr i w i in
28
10
TR<5
31
9
ND<,5
29
9
3
30
10
1
30
12
o
C.
25
10
ND<1
29
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APPENDIX B
SELECTION OF EBB AND FLOOD TIDE SAMPLING CONDITIONS
One of the objectives of this program was to evaluate dechlorination
during the two different tide conditions, ebb and flood. 14 sampling periods
of each ebb and flood tide conditions were selected using the tide table
(Table B-l ). Tides were selected to correspond with the chlorination/dechlor-
ination cycle at the power plant. Tide conditions were selected for 0900 and
1500 chlorination cycles with careful attention that tide conditions did not
change during a sampling period.
Low and high tides indicated in Table B-l are referenced to the Golden
Gate bridge. Times were corrected for the difference in tide times at the
Potrero power plant. Based on information from plant personnel and visual
observation an adjustment of approximately 30 additional minutes to the times
in Table B-l was deemed necessary. Table B-2 presents the date, time and tide
for each of the samples collected.
30
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TABLE B-l. TIDES AT SAN FRANCISCO (Golden Gate), CALIFORNIA - 1979
Pacific Daylight Saving Time
(Heights in feet)
SEPTEMBER
Day
Sat.
Sun.
Mon.
Tue.
Wed.
Thu.
Fri.
Sat.
Sun.
Mon.
Tue.
Wed.
Thu.
Fri.
Sat.
Sun.
Mon.
Tue.
Wed.
Thu.
Fri.
Sat.
Time and Height of High and
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Time Ht.
0134 0.5
0231 0.1
0324 -0.4
0411 -0.7
0457 -0.8
0539 -0.7
Hi Water
0023 6.3
0118 6.0
0214 5.6
0314 5.1
0423 4.7
0540 4.4
0705 4.4
Lo Water
0059 0.6
0203 0.6
0257 0.5
0341 0.4
0419 0.4
0454 0.4
0526 0.5
0555 0.7
Hi Water
0038 5.1
Time
0857
0952
1038
1117
1156
1234
Ht.
4.2
4.6
4.9
5.2
5.4
5.7
Lo Water
0625
0707
0753
0841
0933
1039
1155
0.5
0.0
0.6
1.3
1.9
2.4
2.7
Hi Water
0825
0918
1008
1045
1119
1146
1213
1238
Lo
0626
4.5
4.7
4.9
5.0
5.0
5.1
5.1
5.1
Water
0.9
Time
1329
1431
1526
1617
1707
1756
Low Water
Ht.
2.9
2.6
2.2
1.8
1.3
0.9
Hi Water
1313
1355
1437
1521
1610
1706
1807
5.9
6.0
6.0
6.0
5.9
5.7
5.6
Lo Water
1311
1417
1509
1555
1634
1709
1745
1817
Hi
1304
2.8
2.7
2.4
2.1
1.8
1.6
1.3
1.1
Water
5.2
Time
1941
2044
2140
2235
2330
Ht.
5.9
6.1
6.3
6.5
6.5
Lo Water
1845
1939
2034
2131
2239
2350
0.5
0.4
0.3
0.4
0.5
0.6
Hi water
1909
2012
2108
2159
2242
2321
2359
"
. Lo
1849
5.5
5.5
5.5
5.5
5.4
5.3
5.2
"
Water
1.0
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TABLE B-2. SELECTED SAMPLING TIDES
Sample No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Date
9/5
9/5
9/6
9/6
9/7
9/11
9/11
9/12
9/12
9/13
9/13
9/14
9/14
9/15
9/15
9/16
9/16
9/17
9/17
9/18
9/18
9/19
9/19
9/20
9/20
9/21
9/21
9/22
Time
0900
1500
0900
1500
1500
0900
1530
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
1500
0900
Tide
Flood
Ebb
Flood
Ebb
Ebb
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
Ebb
Flood
32
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TECHNICAL REPORT DATA
(nease read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-80-049
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Residual Oxidants Removal from Coastal Power Plant
Cooling System Discharges: Field Evaluation of SO2
Addition System
5. REPORT DATE
March 1980
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
K. Scheyer and G. Houser
9. PERFORMING ORGANIZATION NAME AND ADDRESS
TRW, Inc.
One Space Park
Redondo Beach, California 90278
10. PROGRAM ELEMENT NO.
INE624A
11. CONTRACT/GRANT NO.
68-02-2613, Task 23
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final: 1-11/79
14. SPONSORING AGENCY CODE
EPA/600/13
IB. SUPPLEMENTARY NOTESIERL_RTP project officer is Julian W. Jones , Mail Drop 61, 919/
541-2489.
16. ABSTRACT
The report gives results of an evaluation of the performance of a dechlor-
ination system that uses SO2 to remove residual oxidants from chlorinated sea
water in a power plant cooling system. Samples of unchlorinated, chlorinated, and
dechlorinated cooling water were obtained at Pacific Gas and Electric's Potrero
power plant in San Francisco. The samples were collected during 28 sampling per-
iods--14 at flood tide and 14 at ebb tideand analyzed for several chemical and
physical constituents. An amperometric titrator was used for field analysis of total
oxidant residual (TOR) and free oxidant residual (FOR). Analytical results, plant
operating data, and laboratory experiments were used to evaluate the dechlorination
system. Major conclusions include: (1) the dechlorination system studied showed
effective removal of residual oxidants from chlorinated sea water used in the power
plant cooling system; (2) the dechlorination system proved reliable (no measurable
oxidant residual was found at the effluent outfall); and (3) due to the effectiveness of
the dechlorination system in removing all measurable oxidant residual, average and
maximum levels of dechlorination cannot be determined.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution Oxidizers
Dechlorination
Cooling Systems
Sea Water
Electric Power Plants
Sulfur Dioxide
Pollution Control
Stationary Sources
Oxidant Removal
13 B HG
07A,07B,07C
13A
08 J
10B
18. DISTRIBUTION STATEMENT
Release to Public
MMMMM^^M^MMi^M^M^M^M
EPA Form 2220-1 (9-73)
19. SECURITY CLASS (This Report)
Unclassified
38
20 SECURITY CLASS (This page)
Unclassified
22. PRICE
33
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