-------
consistent effluent as did the chlorine dosage required to provide ap-
proximately 1 mg/1 total chlorine residual after one hour contact time.
With this effluent, more than 30 minutes were required to meet the min-
imum total coliform quality for effective disinfection, but it was met
without difficulty during the one hour contact period in two of the
three runs when approximately 1 mg/1 total chlorine residual remained.
When the residual was appreciably less than 1 mg/1, the minimum quality
was not achieved during the hour. Fecal coliform results were available
for one of these two runs and the minimum quality was surpassed with
ease in less than 30 minutes in the presence of approximately 0.5 mg/1
total chlorine residual. Results from the third run were entirely dif-
ferent because minimum quality for neither total nor fecal coliforms
was met after an hour contact period with a total chlorine residual of
2.1 mg/1. There may be some question as to when the minimum fecal coli-
form quality was attained during this run, but it appeared to require
approximately 2 hours and 1.5-1.8 mg/1 chlorine residual. The contact
time was approaching 4 hours before minimum total coliform quality was
achieved in the presence of a 1.8 mg/1 residual.
The reason why effluent from this source should occasionally have been so
difficult to disinfect is not clear but the results did suggest that some
factors other than the measured parameters played a role. One point in
which all three runs showed agreement was that coliform numbers continued
to decrease after the first hour, but the rate was much lower than dur-
ing the first hour of contact time.
Again, as with the aerated lagoon effluent (Table 4), this extended aera-
tion effluent proved to be more difficult to disinfect than the primary
effluent (Table 3) even though the chemical and physical parameters
(Table 1) and the initial coliform numbers suggested that the primary ef-
fluent was of lower quality. It should also be noted that both chlorine
demand and disinfection were significantly affected by increasing the
temperature to 25°C (Table 2).
EXTENDED AERATION EFFLUENT (SURFACE AERATOR)
For three consecutive weeks, extended aeration system (surface aerator)
effluent was examined in the same manner as effluents from other sources.
As stated previously, the effluent was atypical during one week and there
was not sufficient time for an extra run, so results from two runs are
presented in Table 6. The chemical and physical parameters (Table 1) sug-
gested that this was a fairly consistent effluent when the system was op-
erating properly. There was sufficient spread between the chlorine dos-
ages required to produce approximately a 1 mg/1 total chlorine residual
in the two runs that it could not be considered a consistent dosage.
Less than 30 minutes were required to meet the minimum bacterial quality
19
-------
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-------
for effective disinfection in both runs when approximately 1 mg/1 total
chlorine residual remained after one hour of contact time, and as little
as 0.5 mg/1 residual was necessary to reduce the total coliforms to well
below the minimum quality in less than 60 minutes contact time. The fe-
cal coliforms had essentially disappeared in less than 30 minutes when
the final total chlorine residual was approximately 1 mg/1. When the
coliforms were enumerated at five minute intervals, the results suggested
that the minimum fecal coliform quality was attained in less than 15 min-
utes and that the total coliform reduction required at least 25 minutes
when the final total chlorine residual was approximately 1 mg/1. Of
course, the rather large difference in the initial total and fecal coli-
form counts probably accentuated any differences in the results between
the two runs.
COMPARATIVE RESULTS
When results from the two extended aeration systems were compared, it was
apparent that disinfection proceeded more rapidly in effluent from the
surface aerator system (Table 6) than in the submerged aerator system
(Table 5) at <1°C. Recorded physical and chemical parameter differences
between these systems were not sufficiently pronounced to provide an ex-
planation for these results. Even though disinfection did proceed more
rapidly in the surface aerator system, the results were still not equal
to those obtained with primary effluent (Table 3).
Primary effluents have been considered more difficult to disinfect to a
predetermined coliform content than secondary effluents (6). This was
borne out to the extent that greater chlorine dosages were required in
the primary effluent (Tables 2 and 3} than in the secondary effluents
(Tables 2, 4, 5 and 6) in order to satisfy the immediate chlorine de-
mand and to provide the desired total chlorine residual. The consis-
tently higher suspended solids concentration in the primary effluent
(Table 1) may have accounted for the greater chlorine demand. However,
a chlorine dosage of approximately 4.5 mg/1 to provide 1 mg/1 residual
after one hour contact time in the primary effluent was not excessive
when compared to the 2.4-4.0 mg/1 dosages required in the secondary
effluents.
When all chlorine dosages and all effluents were considered, it appeared
that most of the one hour chlorine demand was satisfied in the first 1
to 2 minutes of contact time at <1°C and 25°C, with a much lower demand
continuing throughout the hour. The portion of the one hour demand which
was satisfied between dosing and first residual measurement was in excess
of 80 percent in all except one aerated lagoon sample at <1°C and the
primary effluent sample at 25°C. These were 72 and 73 percent of the one
hour demand respectively.
Direct comparison of the 25°C results with the <1°C counterparts which
received the same chlorine dosage showed that a much lower chlorine
21
-------
residual remained after one hour contact time at 25°C and suggested that
temperature had a rather pronounced effect on chlorine demand. Because
of the greater demand at 25°C, the primary effluent one hour chlorine
demand at <1°C was 80 percent of the corresponding 25°C demand, the
aerated lagoon effluent demand was 86 percent and the extended aeration
system (submerged aerator) effluent demand was 81 percent.
22
-------
SECTION VI
DISCUSSION
The objective of this study was to determine if effective treated waste-
water disinfection could be attained with chlorine at less than 1°C
(<1°C). Results obtained with effluents from four waste treatment sys-
tems indicated that there were definite temperature effects. The most
consistent of these effects was on chlorine demand, which was lower at
<1°C than at 25°C by nearly the same percentage in effluents examined
at both temperatures. The rate and/or extent of coliform reduction
during the contact period was also lower at <1°C than at 25°C but the
temperature effect ranged from no apparent effect in the primary efflu-
ent to a pronounced effect in the extended aeration system (submerged
aerator) effluent. These temperature effects did not in themselves ne-
gate the effectiveness of chlorine as a disinfectant at temperatures as
Tow as 0°C because the minimum criteria for effective disinfection were
met with ease in effluents from all sources. The single exception to
meeting the minimum quality was in one sample of extended aeration sys-
tem (submerged aerator) effluent.
Extended aeration system (submerged aerator) and aerated lagoon effluents
were the most difficult to disinfect at <1°C. Both of these systems were
pilot plant operations located on a large military installation and, as
a result, may have received waste containing some "atypical" components
which interfered with the disinfection process. Although military waste
may contain some components not normally found in "typical" civilian do-
mestic waste, such a waste is not atypical in Alaska where a large num-
ber of military installations are located.
Batch treatment is essentially analogous to plug flow which does not
simulate the course of events in most operating disinfection contact
chambers. Batch treatment with continuous mixing and rapid chlorine
injection, as used in this study, had several advantages over most op-
erating contact chambers. The following were among these advantages:
[1] chlorine was thoroughly and rapidly mixed with the effluent; [2]
chamber configuration ensured that all effluent remained in contact
with the chlorine throughout the contact period; and [3] theoretical
and actual contact time were the same. In addition, the effluent chlo-
rine demand was determined immediately prior to treatment. Thus, higher
bacterial quality could be expected after the contact period in this
system than in most operating systems which are plagued with short-cir-
cuiting problems and are usually designed for average rather than max-
imum flow contact time.
During the winter months, climatic conditions in interior Alaska effec-
tively seal all exposed soil and water surfaces, making it unlikely that
coliform bacteria enter waste treatment systems from other than sewered
23
-------
locations. The source of coliforms can probably be further restricted
because there are no industries in the area which contribute unusually
large coliform numbers in the wastes they produce. Thus, coliforms ap-
parently come almost entirely from domestic wastes, suggesting that a
large portion of the total coliform population should give a positive
elevated temperature fecal coliform test. Throughout this study, the
fecal coliforms consistently represented a smaller portion of the total
coliform population than could have been expected if no alterations oc-
curred (12). There are at least three possible explanations for an al-
tered coliform population. Although there is no supporting evidence,
one possible explanation is that the coliform population in the human
intestinal tract is modified when living in a cold environment. The
other two explanations are related to the warm temperature encountered
in the sewage collection and treatment systems during this study. One
of these is differential die-off of fecal and non-fecal coliforms with
the fecal coliform viability being reduced more rapidly. The other pos-
sible explanation was derived from observations during a study currently
in progress which suggested some differential growth enhancement at the
8-10°C temperatures in the collection and treatment systems with some
portion of the non-fecal coliform population increasing in numbers while
the fecal coliform numbers remained nearly constant (15). Similar ob-
servations suggesting enteric bacteria growth in 5-10°C river water were
made by Hendricks and Morrison (17).
Geldreich (12) presented a very comprehensive discussion in which he
pointed out the significance of the fecal coliform portion of the total
coliform population. He showed that the portion of the total coliform
population which did not give a positive fecal coliform test had only a
small chance of originating in warm blooded animal feces, whereas coli-
forms which gave a positive test had very little chance of being from any
other source. Because of this and a more recent compilation of water
quality criteria (22), there is a current effort to place more emphasis
on fecal coliform numbers and de-emphasize or possibly not use total coli-
form numbers when determining the bacterial quality of treated waste-
water and surface water (13). This effort could possibly have the effect
of permitting an increased discharge of non-fecal coliforms to the re-
ceiving water, since the results obtained in this study indicated that
the minimum fecal coliform quality of 200/100 ml was consistently met
with a lower chlorine residual and in a shorter contact time than was the
1000/100 ml minimum total coliform quality at <1°C. The fact that the
fecal coliforms were present in 1-2 orders of magnitude lower numbers
than total coliforms may have accounted for the differences. However,
the results did suggest that the fecal coliforms may have been somewhat
more susceptable to chlorfne disinfection than was the non-fecal portion
of the total coliform population.
When chlorinated effluents from several sources were compared, it be-
came evident that the disinfecting ability of chlorine varied signifi-
24
-------
cantly at <1°C. Thus, an arbitrary chlorine residual after a predeter-
mined contact time cannot be considered prima facie evidence of satis-
factory disinfection, and the chlorine residual:contact time relation-
ship must be established for each effluent to be disinfected (6) at the
lowest effluent temperature encountered. In any event, the only real
measure of satisfactory disinfection is the number of enteric bacteria
being discharged into the receiving water. In batch treatment, the
theoretical and actual contact times are the same. This is not true in
many operating contact chambers. Because of short-circuiting problems,
theoretical contact time has very little meaning and inadequately dis-
infected effluent may be discharged into a receiving water. The result-
ing public health hazards have been well documented (22). These hazards
acquire greatly increased significance in low temperature receiving waters
because of enhanced enteric bacteria survival (14, 28), and because
many people consume surface water without benefit of any form of treat-
ment in Alaska.
Residual chlorine toxicity to aquatic life in receiving waters is beyond
the scope of this discussion. There is a considerable body of litera-
ture from temperate climates indicating that very low levels of chlo-
rine and compounds containing chlorine are toxic to aquatic life (4).
However, there has been no determination of toxic effects in receiving
waters approaching 0°C, and under the additional stress of severely de-
pleted dissolved oxygen. Therefore, it is essential that extreme cau-
tion be exercised in maintaining chlorine residuals no higher and pos-
ibly lower than those established as being non-toxic in warmer receiving
waters until low temperature bioassay studies have been conducted under
Arctic and Subarctic conditions.
25
-------
SECTION VII
REFERENCES
1. American Public Health Association. Standard Methods for the Ex-
amination of Water and Wastewater. 13th Edition. New York, Ameri-
can Public Health Association, 1971. 874 p.
2. American Society of Civil Engineers. Proceedings of the National
Specialty Conference on Disinfection. New York, American Society
of Civil Engineers, 1970. 705 p.
3. Ballentine, R. K., and F. W. Kittrell. Observations of Fecal Coli-
forms in Several Recent Stream Pollution Studies. In: Proceed-
ings of the Symposium on Fecal Coliform Bacteria in Water and Waste-
water. Bureau of Sanitary Engineering, California State Department
of Public Health, 1968. p. 80-126.
4. Brungs, W. A, Effects of Residual Chlorine on Aquatic Life: Liter-
ature Review. Journal Water Pollution Control Federation. In Press.
5. Burns, R. W., and 0. J. Sproul. Virucidal Effects of Chlorine in
Wastewater. Journal Water Pollution Control Federation. 39:1834-
1849, November 1967.
6. Chambers, C. W. Chlorination for Control of Bacteria and Viruses
in Treatment Plant Effluents. Journal Water Pollution Control Fed-
eration. 43_:228-241, February 1971.
7. Chambers, C., and G. Berg. Disinfection and Temperature Influences.
In: International Symposium on Water Pollution Control in Cold Cli-
mates, Murphy, R. S., and D. Nyquist (eds.). Environmental Protec-
tion Agency, Fairbanks, Ak. Publication Number 16100 EXH 11/71.
November 1971. p. 312-328.
8. Collins, H. F., R. E. Selleck, and G. C. White. Problems in Obtain-
ing Adequate Sewage Disinfection. In: Proceedings of the National
Specialty Conference on Disinfection. New York, American Society of
Civil Engineers, 1970. p. 137-161.
9. Coutts, H. J., and C. Christiansen. Extended Aeration in Cold Re-
gions. Environmental Protection Agency, Fairbanks, Ak. In Prepar-
ation. 1973.
10. Environmental Protection Agency, Region X. Disinfection Criteria
and Design Guidelines. Environmental Protection Agency, Seattle,
Wa. December 1970. 6 p.
11. Federal Water Pollution Control Administration. Current Practices
in Water Microbiology. Federal Water Pollution Control Administra-
tion, Cincinnati, Ohio. February 1970.
26
-------
12. Geldreich, E. E. Sanitary Significance of Fecal Coliforms in the
Environment. Federal Water Pollution Control Administration, Cin-
cinnati, Ohio. Publication Number WP-20-3. November 1966. 122 p.
13. Geldreich, E. E. Personal Communication. Environmental Protection
Agency, Cincinnati, Ohio. 1973.
14. Gordon, R. C. Winter Survival of Fecal Indicator Bacteria in a
Subarctic Alaskan River. Environmental Protection Agency, Fairbanks,
Ak. Publication Number EPA-R2-72-013. August 1972. 41 p.
15. Gordon, R. C., C. V. Davenport, and B. H. Reid. Unpublished Data.
Environmental Protection Agency, Fairbanks, Ak. 1973.
16. Heathman, L. S., B. S. Pierce, and P. Kabler. Resistance of Var-
ious Strains of E.. typhi and Coli Aerogenes to Chlorine and Chlora-
mine. Public Health Reports. 51_: 1367-1387, October 1936.
17. Hendricks, C. W., and S. M. Morrison. Multiplication and Growth
of Selected Enteric Bacteria in Clear Mountain Stream Water. Water
Research (Oxford). 1:567-576, August/September 1967.
18. Heukelekian, H., and S. D. Faust. Compatibility of Wastewater Dis-
infection by Chlorination. Journal Water Pollution Control Federa-
tion. 33_:932-942, September 1961.
19. Kott, Y. Chlorination Dynamics in Wastewater Effluents. In: Pro-
ceedings of the National Specialty Conference on Disinfection. New
York, American Society of Civil Engineers, 1970. p. 585-608.
20. Lin, S. Evaluation of Coliform Tests for Chlorinated Secondary Ef-
fluents. Journal Water Pollution Control Federation. 45:498-506,
March 1973.
21. Marias, A. F., E. M. Nupen, G. J. Stander, and J. R. H. Hoffman.
A Comparison of the Inactivation of Escherichia coli I and Polio
Virus in Polluted and Unpolluted Waters by Chlorination. In: In-
ternational Conference on Water for Peace. 1967. p. 670-689.
22. Mechalas, B. J., K. K. Hekimian, L. A. Schinazi, and R. H. Dudley.
Water Quality Criteria Data Book, Vol. 4, An Investigation into Rec-
reational Water Quality. Environmental Protection Agency, Washing-
ton, D. C. Publication Number 18040 DAZ 04/72. April 1972. 256 p.
23. Monroe, D. W., and D. C. Phillips. Chlorine Disinfection in Final
Settling Basins. In: Proceedings of the National Specialty Con-
ference on Disinfection. New York, American Society of Civil Engi-
neers, 1970. p. 163-177.
27
-------
24. Rhines, C. E. Fundamental Principles of Sewage Chlorination. In:
Proceedings, 20th Industrial Waste Conference. Lafayette, Purdue
University, 1965. p. 673-678.
25. Rudolfs, W., and H. W. Gehm. Sewage Chlorination Studies. Bulle-
tin 601. New Jersey Agricultural Experiment Station. March 1936.
72 p.
26. Slanetz, L. W., C. H. Bartley, T. 6. Metcalf, and R. Nesman. Sur-
vival of Enteric Bacteria and Viruses in Municipal Sewage Lagoons.
In: 2nd International Symposium for Waste Treatment Lagoons,
McKinney, R. E. (ed.). Meseraull Printing, Inc., 1970. p. 132-141
27. Technicon Corp. Ammonia in Water and Waste Water. Industrial
Method IND-18-69W, Technicon AutoAnalyzer Methodology. Technicon
Corp., Tarrytown, N. Y., 1969.
28. VanDonsel, D., R. C. Gordon, and C. V. Davenport. Unpublished
Data. Environmental Protection Agency, Fairbanks, Ak. 1973.
29. White, G. C. Handbook of Chlorination. New York, Van Nostrand
Rheinhold Co., 1972. 744 p.
28
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SECTION VIII
GLOSSARY
Anaerobic - Condition under which no free oxygen is present.
Arctic - Area north of the 10°C isotherm for the warmest month and the
-10°C isotherm for the coldest month of the year.
Bactericidal - Killing or having the power to kill bacteria.
Batch Treatment - A quantity of effluent disinfected in such a manner
that all portions receive the same exposure to the disinfectant.
Chloramine - Any compound containing an ammonia molecule in which one
or more chlorine atoms has replaced hydrogen atoms in the ammonia por-
tion of the compound.
Chlorine Demand - The difference between the amount of chlorine added to
an effluent and the amount measured as total chlorine after a specified
contact time.
Chlorine Residual - The amount of chlorine remaining in an effluent and
measurable as total chlorine after a specified contact time.
COD (Chemical Oxygen Demand) - Measure of the oxygen equivalent of that
portion of the organic matter in an effluent sample that is susceptible
to oxidation by a strong chemical oxidant.
Composite Sample - Equal effluent volumes collected at selected time in-
tervals and pooled throughout a predetermined time span to provide the
final sample for analysis.
Contact Chamber - A chamber in which the effluent and chlorine are con-
tinuously mixed for a specified length of time to achieve disinfection.
Contact Time (Period) - The length of time effluent and chlorine are
held in the contact chamber.
Disinfectant - An agent which destroys harmful bacteria.
Disinfection - The act or process of destroying harmful bacteria.
Domestic Waste - Water carried waste which is mostly from kitchen, bath-
room, lavatory, toilet and laundry.
Effluent - Liquid portion of the waste which is discharged from a waste
treatment system or contact chamber.
29
-------
Enteric Bacteria - Bacteria which inhabit the lower intestinal tract of
humans or other warm-blooded animals.
Fecal Conform - A total coliform bacteria subgroup which is specifi-
cally found in the feces of humans and other warm-blooded animals.
Germicidal - See disinfectant definition.
Grab Sample - Effluent sample taken for analysis at one point in time as
opposed to composite sample.
Parameter - A determination which defines the condition of the system
relative to that determination.
Plug Flow - Ideal continuous flow in which all of the effluent has the
same residence time.
Primary Waste Treatment - The removal of settleable organic and inor-
ganic solids by the process of sedimentation.
Pure Culture - A single strain or species of bacteria free from other
bacteria.
Receiving Water - Body of water into which the liquid portion of the
treated wastewater is discharged.
Secondary Waste Treatment - Treatment of sewage by biological methods
following primary treatment.
Short-Clrcuiting - The extent to which portions of the effluent enter-
ing the contact chamber at the same time receive less than theoretical
contact time.,
Solids - Residue remaining after various treatments of the effluent, i.e.
evaporation of water.
Subarctic - Areas where the mean temperature is higher than 10°C for less
than four months of the year and the mean temperature for the coldest
month is less than 0°C.
Survival (Bacterial) - Continuation of viability under adverse conditions,
Temperate Climate - Any area north of the Tropic of Cancer not pre-
viously defined as Arctic or Subarctic.
Theoretical Contact Time - The length of time that a volume of effluent
and chlorine are in the contact chamber if no short-circuiting occurs.
30
-------
Total Coliform - Heterogenous group of bacteria which meet certain mor-
phological and biochemical criteria, and are found in feces of human and
other warm-blooded animals, as well as in other environmental situations.
Unit Process - Distinct operations which are employed to produce an ef-
fluent of the desired quality.
Viability - The capacity of bacterial cells to grow and reproduce if ap-
propriate conditions are present.
31
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Subject Field & Group
05D
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
U.S. Environmental Protection Agency, NERC-Corvallis, Arctic Environmental Research
Laboratory, College, Alaska 99701
Title
Batch Disinfection of Treated Wastewater with Chlorine at Less Than 1°C
|Q Authotfs)
Gordon, Ronald C. and
Davenport, Charlotte V.
16
21
Project Designation
Project 16100 GKG
Note
Environmental Protection
EPA-660/2-73-005
Technology Series
22
Citation
23
Descriptors (Starred Fitst)
*Disinfection, *Wastewater, *8ioindicators, *Coliforms, *Chlorine, *Winter,
Alaska, Bacteria
25
Identifiers (Starred First)
*Total Coliforms, *Fecal Coliforms, *Batch Disinfection, *Low Temperature
27 Absltact A laboratory study was conducted, using batch treatment technique, to gain
some insight into chlorine disinfection of waste treatment system effluents at less than 1°C.
One primary and three secondary effluents were examined at the low temperature with parallel
control samples at 25°C. Effluent disinfection was considered minimally effective if, after
one hour contact time in the presence of 1 mg/1 total chlorine residual, there were no more
than 1000 total and 200 fecal coliforms/100 ml.
The results indicated that both chlorine demand and the rate or extent of coliform reduc-
tion were decreased at the low temperature. The disinfecting ability of chlorine varied sig-
nificantly at less than 1°C, among the four effluents studied. These effects did not in them-
selves negate the effectiveness of chlorine as a disinfectant at low temperature because the
previously stated minimums were easily met in effluent from all sources. However, higher
bacterial quality can be expected from batch treatment than is found in most short-circuit
plagued operating contact chambers.
The only real measure of satisfactory disinfection is the number of enteric bacteria
being discharged into the receiving water. An arbitrary chlorine residual after a predeter-
mined contact time cannot be considered prima facie evidence of satisfactory disinfection be-
cause of the variable disinfecting ability of chlorine. The chlorine residual:contact time
relationship must be established for each effluent at the lowest temperature encountered in
the system.
Abstractor
Institution
f»R:
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