EPA-430/9-75-012
MARCH 1976
DISINFECTION
OF
WASTEWATER
TASK FORCE REPORT
U.S. ENVIRONMENTAL PROTECTION A6ENCY
Washington, D.C. 20460
MCD-21
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EPA REVIEW NOTICE
This report has been reviewed by the Environmental Protection Agency
and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the Environ-
mental Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation of use.
NOTES
To order this publication, MCD-2T, write to:
General Services Administration (8-FSS)
Centralized Mailing List Services
Bldg. 41, Denver Federal Center
Denver, Colorado 80225
Please indicate the MCD number and title of publication.
The publication should be placed in Part III, Guidelines of
the Municipal Wastewater Treatment Works Construction Grants
Program manual.
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EPA-430/9-75-012
MARCH 1976
DISINFECTION
OF
WASTEWATER
TASK FORCE REPORT
U.S. ENVIRONMENTAL PROTECTION AGENCY
Washington, D.C. 20460
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TASK FORCE MEMBERS
Alan Hais (Chairman) - Office of Water and Hazardous Materials
John Stamberg (former Chairman)
Joseph Cotruvo - Office of Planning and Managment
Lehn Potter - Office of Water and Harardous Materials
William Sonnet - Office of Enforcement
Cecil Chambers - Office of Research and Development
James Basilico - Office of Research and Development
William Brungs - Office of Research and Development
Edward Opatken - Office of Research and Development
Edward Brooks - Office of Water and Harardous Materials
Pamela Quinn - Office of General Counsel
Lyndell Harrington - Region VII
ACKNOWLEDGEMENTS
The following personnel from the Office of Research and Development
contributed to the preparation of the Task Force Report:
Office of Environmental Engineering
Municipal Pollution Control Division
William A. Rosenkranz
James V. Basilico
Edward J. Opatken
NERC, Cincinnati
Advanced Waste Treatment Research Laboratory
Cecil Chambers
Office of Environmental Science
Ecological Processes and Effects Division
Frank G. Wilkes
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Water Supply Research Division
Hend Gorchev
NERC, CorvaTIis
National Water Quality Laboratory, Duluth, Minnesota
William A. Brungs
William P. Davis
National Marine Water Quality Laboratory, Naragansett, Rhode Island
Victor Cabelli
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CONTENTS
Section Title Page
I Summary 1
II Conclusions and Recommendations 3
III Indroduction 6
IV Public Health Effects 8
V Effects of Disinfectants and Aquatic Life 13
VI Disinfection Process Alternatives 21
VII Appendices
A. Research and Development Projects 41
B. State Standards (Existing) 43
C. Public Health Effects Tables and Figures 44
D. References 51
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SECTION I - SUMMARY
Task Force Origin
An intra-agency Task Force was formed in early 1974 to develop the neces-
sary background information for consideration of agency policy on wastewater
disinfection requirements and the use of chlorine. During that time the major
consideration of the Task Force was the need for universal year-round dis-
infection and whether the present secondary treatment regulation should be
modified to allow flexibility. Since the input to the final report would
originate from ORD personnel, ORD was requested by the Deputy Assistant
Administrator for Water Programs, OWPO, on December 3, 1974, to assume the
responsibility of completing the Task Force report.
Objective of the Task Force
The main objective of the ORD Disinfection Policy Task Force was to provide
information in the form of guidance on public health and water quality require-
ments, the potential toxic effects of chlorination to both the aquatic and human
environments and alternate methods for disinfection. More specifically the
Task Force objective was to prepare a summary report for use by the Office
of Water Programs Operations in dealing with the chlorine issue and in planning
disinfection policy regarding the need to revise the disinfection requirements
to meet secondary treatment regulations.
Summary
The members of the Task Force have objectively reviewed all aspects of
wastewater disinfection with regards to public health and water quality require-
ments, toxic effects and availability of alternate processes. As a result of
this review the Task Force findings may be highlighted as follows:
1. Disinfection of sewage effluents does provide an effective means of
reducing to a safe level the hazards of infectious disease in receiving
waters. The requirements for disinfection are based on public health
considerations and have greatly reduced waterborne disease outbreaks.
Under certain circumstances and locations such as high dilution and
die off, seasonal recreation, and no downstream reuse potential, the
benefits of disinfection for protection of public health are minimized
and may not be needed. The reaction by-products of certain disinfec-
tants have been identified with potential health hazards; these proper-
ties must be considered when disinfection is practiced.
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2. The toxic effects of total residual chlorine on fresh water organisms
have been further confirmed at very low concentrations. Dechlorina-
tion greatly reduces or eliminates the toxicity caused by residual ch-
lorine; its effect on reducing chlorinated organics is not known. Bro-
minated effluent may be as toxic as chlorinated effluent, but its toxic-
ity is reduced to no-effect concentrations in a much shorter period of
time than chlorinated effluent (minutes instead of hours). No acute
adverse effects from ozonated effluents were observed. There is
limited information on the effects of chlorine residuals on marine
and estuarine life.
3. There are satisfactory alternate disinfection processes that could be
substituted in place of chlorination. Results have shown that dechlor-
ination is effective in reducing the toxic effects associated with resi-
dual combined chlorine. Ozone is an effective disinfectant when applied
to tertiary treated effluents. Bromine chloride is an effective disinfec-
tant on secondary effluent with less toxic effects than chlorine to
aquatic life. Recent improvements in ultraviolet light disinfection
equipment design gives this process improved potential for wastewater
application.
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SECTION II CONCLUSIONS and RECOMMENDATIONS
Conclusions
The Task Force believes that the disinfection of wastewater for pathogen
destruction is of obvious public health importance since these organisms, if not
destroyed, could be transmitted to man through sewage contamination of water
for drinking, food processing, irrigation, shellfish culture or recreational pur-
poses. However the application of disinfection regulations should be periodically
updated to take advantage of new findings and technology in order that EPA make
prudent and efficient use of our nation's resources in administering the secondary
treatment regulations. There are a number of conclusions that can be made from
this Task Force report that would help to support new policy decisions on dis-
infection. These conclusions are listed in the discussion that follows.
1. Disinfection of wastewaters is needed for protecting the public health
when the receiving water is used for water supply, recreation, irrigation,
etc. Although disinfection of drinking water is an essential step for
protecting public health, the disinfection of wastewaters should more
appropriately be decided on a case-by-case basis taking into consideration
the effects of wastewater disposal practice on the different waster uses.
2. Chlorine is currently the predominant wastewater disinfectant and it is
essentially the exclusive disinfectant if one includes its counterpart,
sodium hypochlorite. Disinfection of secondary effluents with chlorine
can reliably meet the present bacteriological standards for secondary
treatment.
3. Disinfection of water and wastewater with chlorine can result in forma-
tion of halogenated organic compounds that are potentially toxic to man.
4. Disinfection of wastewaters with chlorine can result in a residual ch-
lorine level that is toxic to fish. Although additional research needs
to be conducted, available data indicate that chlorine concentrations
below 0.01 mg/1 and 0.002 mg/1 have no adverse effects on warm water
and cold water fish respectively.
Available data, though limited, indicated that chlorine at concen-
trations in excess of 0.01 mg/1 poses a serious hazard to marine and
estuarine life. Additional study of many organism types under a wide
variety of environmental conditions is needed to establish definitive
criteria for chlorine.
5. Dechlorination with suflur dioxide is practiced at full scale facilities
where chlorine residuals must be eliminated. Although no criteria for
dechlorination chemicals can be proposed at this time, no adverse acute
effects were observed on fish following dechlorination with sulfur
dioxide.
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6. Dechlorination with carbon is feasible but costly. Additional research
is required to provide accurate cost and operating data. Health effects
research is also required to establish if carbon is effective for remov-
ing the potentially toxic compounds formed during chlorination.
7. Ozone is finding acceptance at a few full scale plants. As of now, secon-
dary effluents will require filtration as a teriary treatment stage to
consistently meet the fecal coliform standard (200 fecal coliforms/100 ml)
with ozonation. No criteria can be estimated as yet for ozone although
data on fish toxicity indicate that the effluent disinfected with ozone
is less toxic than with chlorinated effluent.
8. Bromine chloride is the newest disinfectant in the field of alternates.
It is an effective disinfectant for secondary effluents and it is less
toxic to aquatic life than chlorine. Health effects are unknown.
9. Although ultraviolet light has not been widely used to disinfect waste-
water, there is limited information that indicates it may become a po-
tentially desirable alternative. It is the only physical process whereas
all the other disinfectants are chemical processes. On-going research
will provide answers as to its applicability to adequately disinfect
wastewater.
Recommendations
The Task Force feels that when disinfection standards are set, the interests
of human health have to be considered paramount. As with all environmental
decisions, we may still have to consider a trade-off of values in which it may
be necessary to compromise the optimum natural ecology of limited stretches
of receiving waters to the greater interest of protecting human life.
The basis for establishment of disinfection standards has been subject to
controversy for many years. The summary of the states' disinfection regulations
show many different requirements and further compounds the issue of uniform
secondary treatment standards. In view of the many factors presented in this
report and considered by the Task Force, the following recommendations are made:
1. Disinfection of wastewaters is needed to protect public health where the
receiving waters are used for purposes such as downstream water supply,
recreatioii, irrigation, shellfish harvesting, etc.
2. Modify the present standards and regulations for disinfection in order to
allow flexibility in regard to year-round requirements. Also where it can
be demonstrated that the protection public health is not involved addi-
tional flexibility should be allowed in the consideration of across the
broad disinfection. Criteria should be developed for these areas.
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3. The exclusive use of chlorine for disinfection should not be continued
where protection of aquatic life is of primary consideration. However
when chlorine is used, the residual combined chlorine in the receiving
waters should not exceed the recommended levels. Use of alternate pro-
cesses should be encouraged by the Agency through a vigorous promotion
of the new alternates.
4. The use of alternate disinfectants should be further pursued because of
recent findings of the potentially hazardous halogenated organics in
drinking water.
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SECTION III - INTRODUCTION
BACKGROUND
Prior to the enactment of P.L. 92-500, domestic wastewater disinfection
practice was, for the most part, controlled locally by the States. Disinfection
requirements were based on water quality standards and/or specific disinfection
criteria which applied to the discharge of wastewater. Implementation of disin-
fection policy through the States generally resulted in flexible requirements
which were related to the protection of public health. Seasonal disinfection of
wastewater was practiced in many States, while no disinfection was required for
certain wastewaters where such a discharge did not endanger public health. The
present regulations require continuous disinfection of all domestic wastewater
on the basis that disinfection is an "important element of secondary treatment
which is necessary for protection of public health." The selection of the disin-
fection process to meet the fecal coliform limitations was limited to chlorination
since it was the only wastewater disinfection process available for widespread
use by municipal wastewater treatment plants. The net result was EPA policy
in conjunction with available disinfection technology encouraged the use of chlo-
rination.
Before the enactment of P.L. 92-500, little consideration was given to poss-
ible effects that indiscriminate use of chlorine might have on fish and other aqua-
tic organisms. These adverse effects were clearly brought out in a memorandum
"Problems with Chlorination of Effluents", August 24, 1970, to the Federal
Water Quality Administration Commissioner from the Nation Water Quality Laboratory
Duluth, Minnesota. However the cost, reliability and potential impact of the
alternative disinfectants were questionable at that time to adopt a significant
change in FWQA's position with respect to disinfection techniques. Also at that
time, the formation of halogenated organics and other reaction by-products was
recognized but the extent and magnitude was not quantitatively defined. Only
recently, through improvements in analytical techniques and the public concern
for drinking water quality, has the potential health hazard of halogenated organics
been brought out.
An R&D program was approved for implementation to develop disinfection alter-
natives and the necessary bioassay support work. Consistent with the state-of-
the-art at that time, emphasis was put on further developing the dechlorination
and ozonation processes as the likely candidates that could supplement chlorination.
Top priority was given to the need for developing new alternatives to chlor-
ination. The grant with the City of Wyoming, Michigan, is the major part of this
program. Although the project is only 50% completed it has produced significant
results and has shown that dechlorination, ozonation and bromine chloride are
effective processes with lesser toxic effects than chlorine. Recent improvements
in UV equipment design gives this process greater potential to wastewater applica-
tions, especially for small plants.
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Additional bioassay information on chlorine toxicity and new bioassay data
on dechlorination, ozone and bromine chloride have been obtained. Some defini-
tive water quality criteria for these disinfectants are being developed but addi-
tional work is needed.
A national survey is being conducted in order to determine the formation
of halogenated organics through disinfection of water supplies. Samples will
be collected from some 80 water supply systems and halogenated organics deter-
mined before and after chlorination.
Research is in progress to provide the data base required for the develop-
ment of recreational water quality criteria. Epidemiological-microbiological
studies are being conducted at several bathing beaches in order to correlate
incidence of diseases among swimmers to some microbial indicators of pollu-
tion. The currently accepted fecal limit for recreational waters will be re-
evaluated in light of new findings. This, in turn, will decide the extent of
wastewater disinfection if recreational waters are to be safe for the public.
The following sections discuss the present status and highlights the research
findings on public health effects, the effects of disinfectants on aquatic life,
and alternative disinfection processes.
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SECTION IV - PUBLIC HEALTH EFFECTS
Rationale for Disinfection
A variety of infectious microorganisms are found in the feces of active
cases or carriers and, hence, in municipal wastewaters containing the fecal
wastes from such individuals. Included are salmonellae, shigellae, entero-
pathogenic Escherichia coli, Pseudomanas aeruginosa and a variety of enteric
viruses, including hepatitis (1).Furthermore, outbreaks of gastroenteritis,
typhoid, shigellosis, salmonellosis, ear infections due to Pseudompnas aeruginosa,
and infectious hepatitis have been reported among individuals drinking or swim-
ming in sewage contaminated waters or consuming raw molTuscan shellfish harvested
therefrom (2-7).
The range and densities of pathogens in municipal wastewater effluents are,
of course, dependent on the number of active cases and carriers in the discharg-
ing population at any given time. However, even if it were practical to monitor
raw sewage for the variety of potential pathogens therein, good public health
practice requires the assumption of their presence in sufficient numbers to
produce a reasonable probability of disease even when small quantities of sewage
are injested. The obvious solution to this problem is to reduce the pathogen
density in the target waters receiving municipal wastewaters so that the proba-
bility of "contact" with an infective dose of a particular pathogen is reduced
below some acceptable limit. From experience and judgment, this limit has been
associated with a median fecal coliform density of 14 fecal coliforms or 70 total
coliforms per 100 ml in shellfish growing water (8,9). From a limited quantity
of epidemic!ogical data, it has been associated with 200 fecal coliforms per 100 ml
in primary contact recreational waters (10,11). For raw surface waters to be used
as water supply sources and receiving conventional treatment, the National Academy
of Sciences recommendation is to limit the geometric means of fecal coliform
concentrations to 2,000 per 100 ml (12).
The above water quality criteria can be achieved by the physical removal or
chemical destruction (disinfection) of the pathogens and indicator microorganisms
at the source of their dilution together with natural die-away in transit to the
target. Primary and secondary treatment systems were not designed for nor are
they particularly effective in reducing microbial densities in wastewaters. Their
effectiveness as reported in the literature varies with the organisms being stud-
ied, the type of treatment and the operative conditions during the study (13-15).
In general, the combined effect of primary and secondary treatment does not re-
duce pathogenic bacteria and viruses or indicator bacteria more than 90 percent.
However, the effectiveness of disinfection is enchanced by the removal of solids
and nutrients during treatment.
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Benefits of Disinfection
Chemical disinfection of wastewaters using chlorine is an effective means
of reducing the density of pathogenic and indicator bacteria provided that so-
lids and interfering materials are reduced by preliminary treatment, residual
chlorine levels are maintained at 3-5 mg/liter and the contact time is suffi-
ciently long. Reductions of 99.9 to 99 percent have been reported with salmon-
ellae and coliform bacteria (16,17). Velz (18) notes that is feasible to achieve
and maintain a residual coliform bacterial density of 500/100 ml, representing
an efficiency of 99.995 percent. Bromine chloride (19) and ozone (20) are
reported to be as or more effective than chlorine.
In general, enteroviruses such as poliovirus, coxsackie, etc., appear to
be more resistant than bacteria to chemical disinfectants such as chorine, al-
though the sensitivity varies considerably by species, type, and even strain.
Hepatitis virus is thought to be the most resistant of all. Kelly and Sanderson
(21) found a greater than 99 percent kill of polio virus at residual chlorine
levels at 0.1 to 0.3 mg/1 with a 2 minute contact time. Clarke, et al (22)
reported a 99 percent kill of adenovirus with 0.1 mg/1 HOC! in 12 seconds. At
the same concentration of hypochlorous acid, a 99 percent kill of poliovirus I
and coxsackie virus A2 were attained in 8 minutes and 40 minutes respectively.
Shuval et al (23) in their study of the effects fo chlorination on trickling
filter effluents, reported that residual chlorine at 3 mg/1 with a 30 minute
contact time killed 99 percent of Echo 9 virus and 50 percent of poliovirus I.
Bromine chloride was reported to be more effective than chlorine for the des-
truction of poliovirus II (19).
The introduction of chlorine in the early 1900's for the disinfection of
water supplies resulted in a dramatic decline in waterborne disease outbreaks.
Major cholera and typhoid epidemics attributable to contaminated water supplies
are a thing of the past. Craun and McCabe noted that from 1951 to 1970 about
fourteen waterborne disease outbreaks occured each year in the United States
(24). However, for 1971 and 1972 the rate has increased to an average of 24
outbreaks per year. Most common causes of these outbreaks are: lack of dis-
infection of groundwater, breakdown of chlorination equipment, cross-connections
(25).
In both the shigella (3) and salmonella (2) outbreaks of swimming assocated
illness, there appears to have been a, breakdown in wastewater treatment. In
addition, a number of the reported outbreaks of shellfish associated infectious
hepatitis appear to be associated with the presence of raw sewage (26). There-
fore, it would seem that proper disinfection superimposed on secondary or tertiary
treatment does render wastewater effluents safe for discharge into recreational
and shellfish waters when a prohibited zone is maintained in the "shadow" of
an effluent outfall.
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Need for Disinfection
Disinfection of effluent from a given source is required whenever the
processes of physical removal at the source and dilution during transit to
the target are not sufficient to meet the target area requirements as stated
below.
Standards Required
At the present time, a realistic standard for disinfection can be stated
as follows: The disinfection of wastewater must meet the standards for indi-
cator microogranisms when the receiving stream is used for water supply, rec-
reation or shellfish growing.
Obviously, the above definition "is not fixed in concrete". As advanced
methods for pathogen removal become available and better (in terms of logistics,
economics, ecological and health side effects) disinfectants are developed,
removal, disinfection and dilution can be treated as separate barrier layers in
wastewater disposal and reuse. Even then it would seem judicious to prohibit
water users in the immediate vicinity (in time or space) of wastewater outfalls.
Conditions for Exemption
Exemptions to the requirement for disinfection occur when natural die-away
and a dilution are adequate for meeting the target area requirements or during
those times when there is not potential for adverse health effects; e.g., no
swimming, due to cold weather. The former case has been operative at some
sewage treatment plants along the coast of Southern California which use long
distance, deep ocean outfalls (27-29). The latter exception has been taken by
communities such as New York City which chlorinate only during the swimming
season (30).
Toxic Effects of Disinfectants
1. Residual and Reaction Products
a. Chlorine
It has recently been reported that chlorination of water and wastewater
results in the formation of halogenated organic compounds that are suspected
of being toxic to man.
In his pioneer study, Jolley (31) determined that under experimental
conditions approximating those encountered in wastewater treatment plants,
chlorine-containing organic compounds are present after chorination of the
effluent. Some seventeen chlorine-containing, stable organic compounds
were identified and quantified at the 0.2 to 4.3 ug/1 level. A list of
these chlorination products and their concentrations is given in Table 1.
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Under EPA contract, Eco-Control (32) reviewed the literature for health
hazards associated with these compounds or classes of compounds. Compounds
listed in Table 1 fall under the general classification of (1) chlorophenols,
(2) chlorobenzoic and chlorophenylacetic acids and (3) chlorinated purines
and pyrimidines. It was concluded that although the first two classes of
compounds should not represent significant health hazards at those concentra-
tions, the chlorinated purines and pyrimidines could potentially exhibit some
teratogenic and carincogenic activities.
Bellar et all (33) determined the nature and concentrations of organo-
chlorine compounds in the effluent of a wastewater treatment plant receiving
a mixture of domestic sewage and industrial wastes. Based on the results pre-
sented in Table II, Bellar et al concluded that the increase in chloroform
concentration appears to be due to chlorination. Similar conclusions could
not be reached for the other compounds listed because of small differences in
the concentration levels before and after chlorination.
During the chlorine disinfection of municipal water supplies, Bellar et
al (33) found chloroform, bromodichloromethane, and dibromochloromethane and
assumed that these compounds are formed through the interaction of chlorine
with organic compounds in drinking water. Table III lists the concentration
found at differenct sampling points of a water treatment plant (see figure 1).
Rook (34) found the following compounds to be formed by chlorination of
water supplies: chloroform, bromodichloromethane, dibromochloromethane, and
bromoform. He further postulated that naturally occurring humic substances
are precursors to the formation of these haloforms. The maximum concentrations
found were: chloroform 554 ug/1, bromodichloromethane 20.0 ug/1, dibromo-
chloromethane 13.3 ug/1, and bromoform 10.0 ug/1.
A cursory evaluation of the health effects of some of these compounds was
given by Kraybill (35) and is presented in Table IV. It can be seen both bromoform
and chlorodibromomethane, which are presumably formed during disinfection with
chlorine, are classified as "suspect carcinogens".
A multitude of halogen-containing organic compounds has been found in water
and wastewaters (36). Example of such compounds found in drinking water is
given in Table V presented by McCabe and Tardiff (37). However, these compounds
are not specifically mentioned here s,ince there is yet no evidence indicating
the in-situ formation of these halogenated compounds through the interaction
of chlorine with organic compounds in water or wastewater.
b. Dechlorination
Dechlorination can be effected using reducing agents such as sulfur dioxide,
sodium bisulfite, or sodium sulfite, activated carbon or by aeration for certain
volatile forms of chlorine.
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Free chlorine (HOC1 and OC1) and inorganic chloramines are known to
be destroyed by sulfites and activated carbon (38,39).
There is a need to evaluate the literature and perhaps conduct reasearch
to determine the interaction of halogenated organics such as chloroform with
dechlorinating agents of the types mentioned above. Until more is known on
this subject, it cannot be stated with any certainty that conventional de-
chlorinating agents will efficiently remove halogen-containing organics.
c. Ozone
Ozone is used extensively in Europe for the disinfection of drinking water.
Little is known of the toxicity of ozone in aqueous solutions, its interaction
with organic matter in water and wastewater and the acute and chronic health
effects of the reaction by-products. Additional research is needed in this
area before large scale use of ozone as a substitute for chlorine disinfection
on a wide scale.
d. Other Disinfectants
Bromine, bromine chloride, chlorine dioxide, iodine, permangate, silver,
utlraviolet light have been used to a limited extent for disinfection purposes.
Permanganate and silver have no known application in wastewaters. Drawbacks
for the above include: high cost, toxic side effects, inefficiency under tur-
bid condition, and lack of residual disinfection. The halogen disinfectants
(Br, BrCl, I) will probably exhibit similar properties to chlorine in their
interaction with organic compounds in water and wastewaters. Considerable
work "is needed to evaluate both the short and long term toxicities of these
disinfectants and their reaction products.
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SECTION V. EFFECTS OF DISINFECTANTS ON AQUATIC LIFE
INTRODUCTION
The present emphasis on environmental preservation and human health is
resulting in an increased use of chlorine for disinfection and waste treat-
ment. Recent investigations, including life-cycle studies with aquatic organ-
isms, have greatly clarified the significance of chlorine toxicity. Several
major projects in various stages of development or completion will add to
this understanding, but sufficient data are available to permit estimates of
the maximum levels of total residual chlorine (TRC) that would protect aqua-
tic life.
As with all toxic materials, it is essential to consider potential environ-
mental and chemical effects of toxicity. Merkens (1) states that the toxicity
of chlorinated wastes in rivers will depend not only on the amount of chlorine
added but on the concentration of TRC remaining in solution. He also concluded
that the toxicity of TRC will depend on the relative proportions of free chlorine
and chloramines. This ratio in turn depends on the amount of ammonia originally
present in the water, the amount of chlorine added, pH, temperature, and the
length of time over which the reaction has taken place. This study also concluded
that free chlorine is more toxic than chloramines and that TRC is more toxic at
lower pH (6.3 versus 7.0) because more free.chlorine is present at the lower pH.
Merkens concluded, however, that "the toxicity of the solution is determined in
the main by the total concentration of available chorine and that the toxicities
of the chloramines and free chorine must all be of the same order." Doudoroff
and Katz (2) also stated that the difference between the toxicity to fish of
free chlorine and chloramines is apparently not very great.
FRESHWATER
1. Effects of chlorinated wastewater treatment plant effluent.
The Michigan Department of Natural Resources (3) reported the effects on
caged fish in several receiving streams below wastewater discharges. Fifty
percent of the rainbow trout died with 96 hr. (96-hr TL50) at TRC concentrations
of 0.014 to 0.029 mg/1; some fish died as far as 0.8 mile (1.3 km) below the
outfall. These same discharges were studied when chlorination was temporarily
interrupted and no mortality was observed.
Tsai (4) studied the effects on fish of 156 wastewater treatment plans in
Maryland, Northern Virginia, and Southeastern Pennsylvania. All the plants
discharged chlorinated municipal wastes into small streams containing fish. In
most of the plants in Maryland and Virginia 0.5 to 2.0 mg/1 residual.
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chlorine is maintained in the effluents. Pennsylvania requires 0.5 mg/1
in effluents prior to discharge to natural surface water. Tsai studied
principally fish, but observed typically a clean bottom without living
organisms in the area immediately below the chlorinated outfalls. Unchlor-
inated discharge areas were typically characterized by abundant growths of
wastewater fungi. No fish were found in water with a TRC above 0.37 mg/1,
and the species diversity index reached zero at 0.25 mg/1. A 50% reduction
in species diversity index occurred at 0.10 mg/1. Of the 45 species of fish
observed in the study areas, the brook trout and brown trout were the most
sensitive and were not found at concentration above approximately 0.02 mg/1.
Ten species were not found above 0.05 mg/1.
Arthur ejt al_. (5) studied the effect of chlorinated secondary wastewater
treatment plant effluent containing only domestic sewage effluent on repro-
duction of fathead minnows, Daphnia magna, and the scud Gammarus pseudolimnaeus.
D_. magna apparently was the more sensitive invertebrate species and died at a
TRC concentration of 0.014 mg/1. Successful reproduction occurred at 0.003 mg/1
and below. Scud reproduction was reduced at concentrations above approximately
0.012 mg/1 (1.2 percent effluent). No effects on any life cycle stage, includ-
ing reproduction, of the fathead minnow was observed at a concentration of
0.014 mg/1; adverse effects were observed at 0.042 mg/1. Acute toxicity studies
with eight species of fish, crayfish (Orconectes virilis), scud (Gammarus
pseudolimnaeus), snails (Physa integra and Campeloma decisum), and stoneflies
(Acroneuria lycorias) indicated that the crayfish, snails, and caddisfly larvae
were least sensitive (7-day TL50 values greater than 0.55 mg/1). Seven-day
TL50 values for the other organisms were between 0.083 and 0.261 mg/1; coho
salmon and brook trout were the most sensitive. Nearly 50 percent of these
observed mortalities occurred in the first 20 hr of the acute tests indicating
that the lethal effect of TRC occurs rapidly.
Esvelt ejt al_. (6,7) and Krock and Mason (8) conducted an extensive study
on the toxicity of chlorinated municipal wastewaters entering San Francsico
Bay and surrounding areas. They observed a significant increase in toxicity
following chlorination. Chlorine toxicity was still significant in aged (up
to 3 days) chlorinated wastewater, in which TRC concentrations were as high
as 25 percent of the initial level. Rainbow trout was the most sensitive of
the species tested, followed by the golden shiner and three-spined stickle-
back. A calculated chlorine residual of 0.03 mg/1, based on dilution of
a measured concentration of 2.0 mg/1, reduced plankton photosynthesis by more
than 20 percent of the value obtained with dilution of effluent having no
chlorine residual. Dechlorination with sodium bisulfite also eliminated
chlorine-related toxicity. One of the conclusions of the California study
was that chlorination may be the largest single sources of toxicity in San
Francisco Bay.
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Martens and Servizi (9) and Servizi and Martens (10) observed mortality
of salmon in receiving streams at TRC concentrations as low as 0.02 mg/1.
Determinations of the effect of time on chlorine residuals were made by
sample storage and lagoon retention. Lethal concentrations persisted in
undiluted effluent for at least 50 hours. Twenty to one dilutions resulted
in the chlorine residual declining to a non-detectable concentration after
12 hours. Studies with live cages at points downstream from the effluent
demonstrated acutely lethal conditions that did not persist during periods
when the chlorinator was inoperable.
An ongoing project with the City of Wyoming, Michigan sponsored by the
U.S. Environmental Protection Agecny, has studied the chronic effects of
various disinfection techniques on the fathead minnow. While the results
are incomplete and statistically untested, it appears that the toxicity of
this chlorinated effluent is similar to that described above. This study
was performed at the Grandville Sewage Treatment Plant and was the first
phase of this project.
As indicated previously many wastewater treatment plants are required
to maintain a residual chlorine concentration of 0.5 to 2.0 mg/1. Most oper-
ators use the orthotolidine method which has been frequently shown to be in-
accurate resulting in much higher concentrations than necessary for adequate
disinfection. This compounds the toxicity problems in the receiving waters.
Total residual chlorine concentrations in 20 Illinois effluents ranged from
0.98 to 5.17 mg/1 (11). A similiar study at 22 plants in southern Wisconsin
resulted in observed concentrations of TRC between 0.18 to 10.3 mg/1 (12).
Both studies demonstrated that the orthotolidine methods provided the poorest
results when compared with other methods such as the amperometric titration
technique. Other studies (9,10) reached the same conclusion that the commonly
used orthotolidine method is inadequate to determine TRC in wastewaters or
receiving streams.
2. Effects of dechlorinated wastewater treatment plant effluent.
Several of the cited studies also evaluated the effect of various dechlor-
ination techniques on the toxicity characteristic of chlorinated wastes. Under
laboratory bioassay conditions dechlorination with sodium thiosulfate at several
Michigan plants resulted in no acute toxicity tests by Arthur ejt al_. (5) using
sulfur dioxide for dechlorination indicated that the toxicity was greatly re-
duced or eliminated. In the latter study the highest effluent concentration
tested in the chronic studies was 20 percent; 100 percent effluent was the high-
est concentration in the acute studies. Preliminary results at the Grandville,
Michigan plant have not been statistically analyzed but there may have been
slight chronic effects at effluent concentrations of 100 and 50 percent dechlor-
inated waste. No effect was indicated at 25 percent. During this study there
also may have been adverse effects in the undiluted, untreated waste.
15
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The Canadian studies (9,13) observed no acute salmon mortality in undiluted
effluent after dechlorination by storage in a lagoon. They also stated that
several California cities will soon be dechlorinating with sulfur dioxide.
The toxicity studies in California (6,7,8) observed that acute mortality in
undiluted effluent was totally eliminated by dechlorination with sodium bi-
sulfite.
3. Effects of alternative disinfection of wastewater treatment plant effluent.
a. Ozone
There is a lack of toxicity data for ozonated effluent at this time. No
measurable toxicity to aquatic life was found in chronic tests by Arthur et al.
(5) using a 20% concentration of waste disinfected with ozone. Unrealistically
high concentrations of ozone, relative to that needed for disinfection, were
necessary to maintained concentrations of 0.2 to 0.3 mg/1 in a testing system
where acute mortality occurred. Typically, ozone dissipated rapidly between
the contact chamber and the test chambers. Preliminary results of comparable
studies at the Grandville, Michigan waste treatment plant indicate that the
ozonated effluent had no significant effect on fathead minnow reproduction,
growth-, or survival.
During a 6-week pilot plant study by Nebel ert al_. (13) there was no mor-
tality of bass, perch, minnows, and goldfish exposed to undiluted ozonated
effluent at the Fort Southworth treatment plant in Louisville. These same
species did not survive in the non-disinfected secondary effluent. Spawning
in the undiluted, ozonated effluent at Grandville was apparently increased
over that in the raw effluent.
B. Bromine chloride
The only significant data on the toxicity of brominated wastewater effluent
are preliminary data from the Grandville project. The acute toxicity of this
effluent is similar to that for chlorine but the toxicity of this effluent de-
clines at a much greater rate than that for chlorine. The same is true for
the chronic test. A 25 percent effluent concentration (0.18 mg/1 bromine
residual) had no chronic effect on reproduction of the fathead minnow, where-
as a 20 percent effluent concentration of chlorinated waste (0.104 mg/1 chlo-
rine residual) killed all the test fish.
The principal characteristic of brominated effluent is that initially it
is as toxic as chlorinated effluent but its toxicity becomes negligible in a
matter of minutes whereas residual chlorine toxicity may persist for many hours.
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MARINE
1. Effects of chlorinated wastewater treatment plant effluent.
Although limited information does exist on the effects of chlorine residuals
on marine and estuarine life, few data are available on the effects of the wide
spectrum of chlorinated hydrocarbons which are introduced into marine ecosystems
by discharge of chlorinated municipal treatment plant effluents. Studies to
identify these compounds, their rates of formation and potential impact on
marine communities have only recently been initiated.
The results of a study by Holland ejt al_ (14) indicate that 0.25 mg/1 chlo-
rine was lethal to Chinook salmon. At an exposure time of 23 days, the maxi-
mum non-lethal concentration of residual chlorine for pink salmon and coho
salmon in sea water was 0.05 mg/1. According to the authors, no chlorimines
were formed in sea water containing 0.05 to 0.5 mg/1 chlorine and 3 mg/1 ammonia.
Alderson (15) found that the 48 and 96 hr TLm for plaice larvae was 0.32 and
0.026 mg/1 free chlorine respectively. After 96 hours exposure to 0.03 mg/1
chlorine, the feeding rate of surviving larvae gradually decreased by 50 per-
cent. Eggs were not affected by exposure to 0.075 and 0.04 mg/1 chlorine solu-
tion for 8 days indicating that the protection of the egg membrane allows normal
development over relatively long periods even at chlorine concentrations which
would be rapidly lethal to hatched larvae. The 72 hr and 192 hr TLm for the
eggs was 0.7 and 0.12 mg/1 respectively.
Muchmore and Epel (16) found that the fertilization success of gametes of
the sea urchin Strongylocentrotus purpuratus exposed to a 10 percent unchlor-
inated sewage-seawater mixture was reduced by 20 percent. Chlorinated sewage
further reduces fertilization success in concentrations as low as 0.05 mg/1
available chlorine. These results indicate that the use of chlorine disinfec-
tion could contribute to reproductive failure in external fertilization of
marine invertebrates in the vicinity of sewage outfalls.
Galtsoff (17) observed that the pumping activity of oysters exposes to
0.01 to 0.05 mg/1 chlorine was reduced. Effective pumping could not be main-
tained at a concentration of 1.0 mg/1.
Tsai (18,19) observed decreases in the abundance and occurance of brackish
water species including the common sucker, Catastomus commersonni, the minnows,
Notropis cornutus, N_. analostanus and N_. prooni, and the catadromous eel,
Anguilla rostrata, in certain areas of the Upper and Little Patuxent Rivers
receiving chlorinated sewage treatment effluents.
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Additional evidence for the effects of chlorine on marine environments
may be found from studies of the effects of chlorination of sea water on
the survival of fouling organisms and on phytoplankton production. Waugh
(19) observed no significant difference in the mortality of oyster larvae,
Ostrea edulis, exposed to 5 mg/1 chlorine for 3 minutes at ambient temper-
ature compared to control mortality. Exposure of larvae to thermal stress
(10 C above ambient) and 10 mg/1 chlorine for 6 to 48 minutes also had no
significant effect on survival, 46 and 64 hours after treatment. Barnaole
nauplii, Elminius modestus showed more acute sensitivity to chlorine. Re-
sidual chlorine concentrations in excess of 0.5 mg/1 caused heavy mortality
and reduced growth for survivors.
McLean (21) simulated the conditions encountered by marine organisms
passing through a power plant on the Patuxent River, Maryland. Intake chlor-
ination to 2.5 mg/1 residual, entrainment for approximately 3 minutes and
sustained exposure to elevated temperatures for up to 3 hours were used as
experimental parameters. While barnacle larvae, Balanus sp. and copepods,
Acariatonai, were not affected by a 3 hour temperature stress of 5.5 and 11
C above ambient; exposure to 2.5 mg/1 residual chlorine for 5 minutes at
ambient temperatures caused respective mortality rates of 80 and 90 percent
3 hours after exposure. Grass shrimp, Palaemontes pugio, and the amphipod,
Melita nitida, showed a delayed death response after exposure to 2.5 mg/1
residual chlorine for 5 minutes. Nearly 100 percent mortality was observed
for both species 96 hours after exposure to the chlorine residual.
Carpenter ejt al_. (22) investigated the effects of chlorination on phyto-
plankton productivity. An 83 percent decrease was observed in the produc-
tivity of phytoplankton passed through the cooling systems of a nuclear gen-
erating plant on Long Island Sound which received 1.2 mg/1 chlorine at the
intake. Essentially no decrease in productivity was observed when phyto-
plankton passed through the cooling system without addition of chlorine.
Hirayama and Hirano (23) found that Skeletonema costatum was killed when
subjected to 1.5 to 2.3 mg/1 chlorine for 5 to 10 minutes.
Gentile ejt al_. (24,25) at the National Marine Water Quality Laboratory,
West Kingston, Rhode Island, observed a 55 percent decrease in the ATP content
of marine phytoplankton exposed to 0.32 mg/1 chlorine residual for two minutes
and 77 percent decrease after 45 minutes of exposure to chlorine concentra-
tions below 0.01 mg/1. A 50 percent depression in the growth rates of 10
species of marine phytoplankton exposed to chlorine concentrations ranging
from 0.075 to 0.25 mg/1 for 24 hours was also measured.
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2. Effects of dechlorinated wastewater treatment plant effluent.
No information is available on the effects of dechlorinated effluents on
marine and estuarine organisms. Extrapolation of freshwater data to marine
ecosystems would indicate, however, that the dechlorination of effluents would
reduce chlorine toxicity significantly.
3. Effects of alternative disinfection of wastewater treatment plant effluent.
Research on the effects of alternative disinfectants such as ozone is only
in preliminary stages relative to marine ecosystems. The agents resulting
from ozonation and UV irradiation have been neither identified nor analyzed
for ecological impact.
RECOMMENDED CRITERIA
1. Freshwater.
Several reviewers of chlorine toxicity have recommended numerical cri-
teria for continuous concentrations of TRC that would not adversely effect
aquatic popultions. Basch and Truchan (26) recommended maximum concentra-
tions of 0.02 and 0.005 mg/1 for warmwater and coldwater fish, respectively.
EIFAC (27) has suggested criteria dependent upon pH and temperature with an
acceptable upper limit of 0.004 mg HOC!/I (TRC from 0.004 mg/1 at pH of 6.0
and 5 C to 0.121 mg/1 at a pH of 9.0 and 25 C). A third review by Brungs
(28) has recommended a criterion of 0.01 mg/1 for warmwater fish and 0.002
mg/1 for coldwater species and the most sensitive fish food organisms.
These criteria may eventually be influenced by ongoing studies that are
investigating chlorinated residues in fish tissues resulting from chlorination
of waste effluents.
No criteria can be considered as yet for ozone and bromine chloride al-
though available data indicated that the toxicity of effluents disinfected
with these materials is less than with chlorinated effluent.
Similarly, no criteria for various dechlorinated chemicals (e.g., sodium
bisulfide, sodium thiosulfate, and sulfur dioxide) can be proposed at this
time. No adverse acute effects of dechlorination have been observed. Pre-
liminary data indicate possible slight chronic effects but only in 100 and
50 percent raw dechlorinated effluent.
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2. Marine
Although chlorination is used to eliminate undesirable levels of organisms
that would degrade water uses, it is evident that the effects of chlorine on
desirable marine and estuarine species is a serious hazard. No information
is available on the effects of toxic chlorinated products on marine life. It
appears, however, that free residual chlorine in sea water in excess of 0.01
mg/1 can be hazardous to marine life. Additional study of many organism types
under a wide variety of environmental conditions is needed to establish a recom-
mended value for chlorine.
CONCLUSIONS
1. Trout, salmon, and some fish-food organisms are more sensitive than
warmwater fish, snails, and crayfish.
2. Chronic toxicity effects of TRC on growth and reproduction occur at
lower concentrations than those causing mortality.
3. Dechlorination with sodium biosulfite, sodium thiolsulfate, and sulfur
dioxide, or certain other compounds, greatly reduces or eliminates toxicity
caused by TRC.
4. Brominated effluent may be as toxic as chlorinated effluent but its
toxicity is reduced to no-effect concentrations in a much shorter period of
time than chlorinated effluent.
5. No acute adverse effects of ozone were observed in as high as 100
percent effluent.
6. Non-disinfected secondary domestic effluents have only slight toxi-
city to freshwater organisms at concentrations as high as 100 percent effluent.
7. Chronic toxicity effects of TRC on marine organisms occur at lower
concentrations than those causing mortality.
8. Sublethal concentrations of chlorine can reduce productivity of marine
phytoplankton.
9. Larval stages of marine forms appear to be more sensitive to chlorine
than either the egg or adult stages.
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SECTION VI - DISINFECTION PROCESS ALTERNATIVES
Program Background
The Municipal Pollution Control Division and the Ecological Processes
and Effects Division have supported an active program in developing new
disinfectants and techniques for application to waste treatment plants efflu-
ents and combined sewer overflows. Many of the completed projects have pro-
vided the basis for the present research program and have greatly contrib-
uted to the present state of the art. A list of completed and on-going pro-
jects is presented in the Appendix to give the reader an overview of the
activity in this area.
An important and major part of the program in this area is an on-going
grant with the city of Wyoming, Michigan. The project was designed to test
the toxicity of residual chlorine to aquatic life; investigate alternative
methods for disinfection of wastewater; and test the toxicty of those methods
to aquatic life. The alternative processes being studied are disinfection
with ozone and bromine chloride, and the neutralization of residual chlorine
in chlorinated effluent with sulfur dioxide. The study is a cooperative
effort between the Grand Valley State Colleges, Allendale, Michigan, and the
cities of Wyoming and Grandville, Michigan. Funding for the bromine chloride
disinfection study has been totally provided by the Dow Chemical Company and
Ethyl Corporation. The Grace Chemical Company has provided ozonation equip-
ment and information dealing with the application of ozone to wastewater.
The following is a discussion on the alternative processes that have been
developed and their general standing in regard to immediate and future appli-
cation.
OPERATIONAL PROCESSES
Liquified Chlorine Gas (Molecular Chlorine)
General
Liquified chlorine gas (subsequently referred to as chlorine) is soluble
in water (0.0608 Ibs/gal. at 20°C). For practical purposes the storage life
of chlorine is essentially unlimited. It assumes two forms in wastewater
that account for most of its disinfecting activity:
1. HOC1 (hypochlorous acid) which is extremely effective in killing
both bacteria and viruses.
2. Monochloramine, the dominant form in wastewater, a persistent but
relatively slow acting disinfectant.
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The reason for the dominance of monochloramine is that practically all waste-
water contains ammonia and most of the chlorine applied is very rapidly con-
verted to monochloramine at normal wastewater pH of slightly above 7.0. Other
chlorinated compounds such as organic chloramines are formed but these are of
little germicidal importance in the disinfection of wastewater.
Status
Chlorine is currently the predominant wastewater disinfectant and it is
essentially the exclusive disinfectant if one includes its counterpart, sodium
hypochlorite, which will be covered subsequently in a separate section. A
minimum chlorine contact time with a specified chlorine residual is included
in some state standards. Others rest on EPA regulations or specify that cer-
tain bacteriological standards be met.
Equipment and Chemical Suppliers
There is a wide variety of sources of equipment for adequately applying
and controlling the use of chlorine for disinfection of wastewater. The field
is extremely competitive. There was some concern for availability of adequate
supplies of both chlorine and shipping containers early in 1974 (1). In the
EPA Disinfection Policy Task Force meeting on July 9, 1974, it was reported
that there was no shortage of either containers or chlorine for water and waste-
water disinfection.
Safety
Liquid chlorine is a hazardous chemical and chlorine gas is toxic and can
cause death by suffocation (2). It irritates the respiratory tract mucous sur-
faces and the skin. Direct contact with liquid chlorine can cause serious
burns. Safey equipment (gas masks) is required for emergency protection in all
potentially dangerous areas. Safety precautions must be excercised in all ship-
ment, storage, and use areas. The liquid vaporizes at atmospheric pressure
and ambient temperatures. The gas is 2-1/2 times as heavy as air and will per-
sist in low areas.
Reliability
Chlorine is generally a reliable disinfectant. There is clear-cut evi-
dence that chlorination of wastewater destroyed enteric pathogenic bacteria.
In a study on the occurrence of Salmonella in the receiving stream after waste-
water chlorination, Salmonella were not detected in either chlorinated effluents
or the receiving stream during a 7-month period when effluents were chlorinated.
After chlorination was discontinued, Salmonella were isolated. When chlorination
was resumed, however, they were not detected in samples collected during a
4-week period (3).
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The value of the coliform test is indicated by the fact that "... epide-
mics of hepatitis originating in chlorinated water supplies judged satisfactory
by the coliform test have not been reported except where obvious deficiencies
in chlorination practice were shown or suspected" (4). Apparently, the coli-
form test provides a good measure of protection against the one virus disease
that has frequently been the cause of waterborne epidemics. Basically, its
effective use for disinfection of wastewater requires an understanding of the
disinfecting efficiency of hypochlorous acid (HOC1) hypochlorite ion (OC1)~
and chloramines (4). The primary disinfectant form of chlorine in current
wastewater treatment practice is monochloramine and other forms of combined
chlorine. Disinfection of secondary effluents can reliably meet stringent
bacteriological standards. Only limited information is available on the
virucidal effect of monochoramine and what is available indicates that it is
a slow acting virucide (5). To ensure adequate protection from viruses, long-
term exposure to monchloramine is required, whereas chlorination to break-
point (HOC1 residual) will rapidly destroy both viruses and bacteria (6).
Research
The present research program is implementing a comprehensive project to
improve chlorine contactor design and mixing under EPA Grant No. 803459, "Re-
duction of Unit Toxicity Emission Rates from Wastewater Treatment Plants by
Optimization of the Chlorination Process." This will include preparation of
a design manual for chlorine contact systems. An improved understanding of the
effect of combined chlorine on viruses is being sought under EPA Grant No. 800370,
"A Comparative Study of the Inactivation of Viruses in Wastewater by Chlorine
and Chlorine Compounds." A search is underway for "New Microbial Indicators
of Disinfection Efficiency," jointly funded by EPA and the Army under an Inter-
agency Agreement EPA-LAG-D4-D432 (formerly EPA Grant No. R-800912).
Improved technology for application of chlorine to effluents from lagoons,
oxidation ponds, and related treatment processes will be investigated under a
contract with Utah State University to "Determine Chlorination Requirements
to Satisfactorily Disinfect Lagoon Effluent to Meet Secondary Treatment Stan-
dards." Award of contract is pending. There is a need for improved instrumenta-
tion for monitoring residual chlorine and automation for better control of dosage
response in relation to residual chlorine.
Costs
With the exception of chlorine much of the cost information presented must
be considered tentative at this time. For example there have been no full scale
plant demonstrations to support cost analysis for wastewater disinfection with
ozone, bromine chloride and ultraviolet light or dechlorination with carbon.
The dosage assumed for chemical disinfectants are 8 mg/1 to achieve disinfection.
Costs of disinfection with chlorine are presented in Table I (7).
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Table I
Chlorine Disinfection Cost
Plant Size, MGD 1 10 100
Capital Cost, $ 60,000 190,000 840,000
Disinfection Cost, tf/K Gal 3.49 1.42 0.70
Sodium Hypochlorite (NaOCl)
General
The disinfecting potency of 1.0 mg/1 of chlorine derived from sodium hypo-
chlorite is just as effective as an equivalent amount of chlorine as hypochlorite
ion (OC1)~ dervived from liquified chlorine gas. Either chlorine gas or sodium
hypochlorite in aqueous solution at concentrations used for wastewater disinfec-
tion, assume the same form and are equally available to react with ammonia or
other wastewater components (4). Sodium hypochlorite is only available as an
aqueous concentrate. The optimum concentration of sodium hypochlorite in terms
of maximum concentration and stability is 15 percent (8). Sodium hypochlorite
solutions must be protect from freezing. The concentrated solution is highly
corrosive to most common metals and wood. Sodium hypochlorite solutions lose
oxidizing power during storage. A solution of sodium hypochlorite that contains
15 percent of available chlorine by volume when stored at 75°F will lose half of
its original activity in 100 days (9). Storage above 850F is not recommended.
Lower concentrations will not deteriorate so rapidly, but increased storage
capacity is required.
Status
Increasingly, certain wastewater treatment plants are turning to the use
of sodium hypochlorite because it is safer than liquified chlorine gas (8).
Two examples suffice to illustrate this point, namely, the cities of New York
and Chicago. A limited number of other plants are making the change for the
same reason - to avoid storage of liquified chlorine gas in plants with close
proximity to heavily populated areas.
Equipment and Chemical Supplies
With the exception of the feeder, storage, and some piping, a hypochlorina-
tion system is very similar to that for a system using liquid chlorine (8).
Equipment is available for on-site generation of sodium hypochlorite or the
chemical can be purchased and stored in tanks; therefore no major supply prob-
lems are anticipated.
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Availability of sodium hypochlorite should be essentially the same as for
chlorine. Chlorine gas is produced by electrolysis of brine with sodium
hydroxide as a by-product. Sodium hypochlorite is produced by recombining
the chlorine with sodium hydroxide.
Safety
The primary reason for using sodium hypochlorite instead of liquified chlo-
rine gas is because it is safer. "Neverthless, it should be clearly understood
that sodium hypochlorite is hazardous and proper safety precautions should be
employed. However, a number of large users, including the cities of New York
and Chicago, are apparently willing to pay the premium for the greater safety
aspects of this product in comparison to liquid chlorine" (8).
Reliability
The active forms of chlorine derived from sodium hypochlorite and liquified
chlorine gas are the same when applied to wastewater. Accordingly, the advan-
tages and disadvantages with regard to disinfection reliability are essentially
the same for sodium hypochlorite and liquified chlorine gas.
Research
Needs essentially the same as for liquid chlorine.
Costs
When considering the entire system of piping, storage tanks, diffusers and
instrumentation and feeders, there is usually only a small percentage of differ-
ence in capital cost of liquid chlorine and sodium hypochlorite systems (9).
Current costs of sodium hypochlorite indicate that available chorine as sodium
hypochlorite costs approximately 2.5 to 10 times more than liquified chlorine
gas depending on the volume treated (10). For comparison, apply these factors
to the disinfection cost in Table I.
Dechlorination with Sulfur Dioxide (S02)
General I
Since chlorination of wastewater causes chlorine residuals that can be
toxic to aquatic life, dechlorination may have to be practiced in some situations.
Sulfur dioxide is the best direct reacting chemical agent available for
wide scale use in dechlorinating wastewater. It is available commercially as
the liquified gas and is much more soluble than chlorine in water (1.0 Ib/gal.
at 60°F). Upon dissolving sulfur dioxide in water a weak solution of sulfurous
acid is formed. The dechlorination reaction of sulfur doxide with both free
25
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and combined chlorine residuals is nearly instantaneous (11). Contact
chambers are not necessary but rapid and complete mixing at the point of
addition is important. The reaction weight ratio of sulfur dioxide to
chlorine is 0.9:1.0 which converts chlorine to the choride ion. The sul-
fur dioxide dosage needed is that sufficient to neutralize the residual
chlorine. Sulfur dioxide appears to be effective in preventing toxic stress
to receiving water biota. There is no reason to expect that its use will
exert any effect on chlorinated organic compounds resulting from disinfection
with chlorine. However, research is required to determine if this assump-
tion is correct.
Status
Sulfur dioxide has long been used to neutralize chlorine in treatment of
drinking water, but its use for dechlorination of wastewater is just getting
underway. Information obtained in October 1974 on four wastewater treatment
plants with average daily flows ranging from 4.0 mgd to 160 mgd indicated no
serious problems in dechlorinating with sulfur dioxide. Of these plants, the
Sacramento City plant (flow 50 mgd) had been using sulfur dioxide dechlorina-
tion for 9 months (12).
Equipment and Chemical Supplies
Equipment for feeding sulfur dioxide is very similar to that used for chlor-
ine and no serious difficulties in the supply situation for equipment or sulfur
dioxide are anticipated.
Safety
Sulfur dioxide is a hazardous highly corrosive and extremely irritating gas
that causes skin and eye burns and damages mucous surfaces. It is self-warning.
It is less prone to rapid volitalization than chlorine (vapor pressure of sulfur
dioxide at 7QOF is 35 psi while the corresponding value for chlorine is 90 psi).
Handling precautions are similar to chlorine but the lower pressures of sulfur
dioxide are less prone to cause leakage problems.
Reliability
Sulfur dioxide is a reliable chemical agent for removing residual chlorine
from water and wastewater. As sulfur dioxide is a reducing agent, careless
operation can lead to reduced dissolved oxygen content of effluents. As a re-
sult, some states are requiring reaeration to increase the dissolved oxygen
content of the effluent when sulfur dioxide is used to dechlorinate.
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Research
An important area where research is needed is in the study of aftergrowth
following dechlorination. Complete removal of bactericidal effects may result
in increased aftergrowth. This problem is likewise anticipated with disinfect-
ants such as ozone and ultraviolet light which leave no lasting residual.
Costs
Costs for both dechlorination with sulfur dioxide and restoration of dis-
solved oxygen content are presented in Table II and III. To obtain the total
cost of disinfection, the chlorination cost in Table I must be added to the
dechlorination and the oxygen restoration cost in Tables II and III (7).
Table II
Dechlorination with Sulfur Dioxide Cost
Plant Size, MGD 1 10 100
Capital Cost, $ 11,000 29,000 94,000
Disinfection Cost,. jfi/K Gal 0,88 0.33 0.19
Table III
Cost for Post Aeration Following Sulfur Dioxide Dechlorination
Plant Size, MGD 1 10 100
Capital Cost, $ 49,000 140,000 650,000
Disinfection Cost, tf/K Gal 3.29 0.64 0.30
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ALTERNATIVE PROCESSES
Dechlorination with Activated Carbon
General
Chlorinated effluent can be dechlorinated by treating the effluent with
activated carbon. This technique is a physical process in which chlorinated
amines, free chlorine and chlorinated organics are removed by sorption on the
carbon. This polishing step not only alleviates the problem of toxicity associ-
ated with chlorine but it also removes residual refractory organics and may
remove some of the potentially toxic chlorinated organics.
Status
Activated carbon is used as a tertiary treatment stage for reducing the
chemical oxygen demand (COD) of wastewater at several waste treatment facili-
ties. This technology is applicable for the design and operation of carbon
systems for dechlorination (13). The practice of dechlorination with activated
carbon is used as a supplementary treatment for water supply by the brewery
and soft drink industries (14). Its use in dechlorinating wastewater treat-
ment has been limited to a pilot plant evaluation at Owosso, Michigan (15).
The results from the Owosso facility proved the feasibility of this process to
adequately remove the free and combined chlorine from the effluent. However
a full scale demonstration is required to establish the cost of dechlorinating
with carbon. This process is the most costly of the many alternatives in regard
to both capital and operating costs.
Equipment and Chemical Suppliers
As mentioned above, activated carbon is used for COD reductions as a ter-
tiary treatment stage. The equipment and material (carbon) is available for
ready implementation. The mode of operation in which the effluent flows thru
a static bed of carbon reduces the operating difficulties normally associated
in dechlorination with chemicals, such as sulfur dioxide. Biological growth
on carbon may reduce the dissolved oxygen level of the effluent and require
post aeration treatment before discharge.
Safety
The operation of a carbon column requires no special precautions. However
when it becomes necessary to perform internal maintenance or inspect the inside
of the carbon column, special safety precautions must be taken to avoid CO and
C02 inhalation or an atmosphere devoid of oxygen.
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Reliability
The Owosso, Michigan pilot plant study for dechlorinating wastewater with
carbon showed that the carbon consistently removed the free and combined chlor-
ine. Long term tests are still required to determine the influence of organic
loadings on the efficiency of the chlorine removals and to determine if after-
growth occurs on the carbon beds.
Research
Dechlorination with carbon is a medium priority process in the program to
develop alternatives to chlorination. Cost estimates have shown this process
to be the most costly alternative. More significantly, the cost estimates as-
sume that the carbon will perform for several years before replacement, there-
by eliminating carbon regeneration facilities. This assumption needs verifica-
tion before such a system can be placed into operation. Since the costs for
dechlorination with carbon are significantly higher than other alternaive proc-
esses, carbon dechlorination research is classified at a medium priority level.
Costs
The cost of dechlorinating with carbon is shown in Table IV (7). The cost
for chlorination is included in the capital and disinfection cost for dechlori-
nation with carbon.
Table IV
Dechlorination with Carbon
Plant Size, MGD 1 10 100
Capital Cost, $ 640,000 2,800,000 8,400,000
Disinfection Cost, rf/K Gal 19.00 8.60 3.28
Because of its high oxidation potential, ozone has received the most atten-
tion as a disinfectant alternative to chlorine. Ozone is a chemical disinfect-
ant that may derive its gernricidal properties from the foramtion of nascent
oxygen in the breakdown of ozone. In addition to disinfection, ozone reduces
the color and odor of wastewater. Although ozone is 13 times more soluble in
water than oxygen, it is difficult to dissolve more than a few mg/1 of ozone
because the ozone gas concentration during generation is between 1 and 3 weight
%. Ozone decomposes in water to form molecular oxygen.
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Status
Ozone has been used for sixty years to treat water supplies in Europe and
Canada. Its use in wastewater applications has been limited to pilot plant
studies to establish feasibility, reliability, process .limitations and cost
information.
Although there are no full scale plants using ozone to disinfect waste-
waters at this time, there are five locations (Springfield, Missouri; Meander
Lake, Ohio; Estes Park, Colorado; Indiantown, Florida; Woodlands, Texas) that
have specified ozone for the disinfection stage. Several of these plants are
now under construction and all five locations have included filtration as a
pretreatment stage for ozonation.
Equipment
Ozone generation consumes more energy than other disinfectants. It is
produced on-site by the application of an electrical discharge across oxygen
or air. This phase is being gradually improved by the many manufacturers of
ozone equipment. At present, approximately 6 kilowatt hours of power are
required to generate one pound of ozone from pure oxygen; whereas 12 kilowatt
hours are required to generate one pound of ozone from air. For comparison,
chlorine uses 1.3 kilowatt hours of electricity to produce one pound of chlorine.
Safety
Ozone is a toxic gas that requires special design considerations to prevent
its escape into an operating area. Vent gases must be treated to convert the
ozone to oxygen before releasing the gas into the atmosphere. The maximum allow-
able concentration for an eight hour day exposure of ozone to humans is 0.1 ppm.
However, the odor of ozone is readily detected. The olfactory threshold odor
concentration for the general population is 0.02 to 0.05 ppm, which enables
operating personnel to take corrective action on sensing ozone (17).
Reliability
Recent pilot plant studies at Wyoming, Michigan, and Chicago, Illinois (18)
have shown that it is difficult to disinfect secondary effluents with ozone and
consistently meet nominal bacteriological standards. Tertiary treatment is re-
quired. Filtration has been shown to be an effective treatment stage to enhance
the disinfection efficiency of ozone.
Research
The EPA research program investigating alternatives in the disinfection of
wastewater has assigned ozone a high priority. Work is underway to optimize !
utilization by improving various contacting systems. Research plans also call
30
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for demonstrating ozone at two of the five previously listed sites. One site
will evaluate ozone produced from pure oxygen and the other site will evaluate
ozone produced from air to obtain comparative cost data for ozone application
as a disinfectant.
Research is still required to find a parameter for controlling ozone dos-
age. Present technology utilizes a constant ozone dosage which results in
excessive ozone comsumption or inadequate disinfection.
Residual oxidation products need to be invest!aged to determine if toxic
compounds are formed when the reaction of ozone with organics do not proceed
to completion (C02 and f^O).
Costs
The costs for disinfecting wastewater with ozone generated from air and
from oxygen are shown in Table V.
Table V
Ozone Disinfection Cost
Ozone Generated from Air
Plant Size, MGD 1 10 100
Capital Cost, $ 190,000 1,070,000 6,880,000
Disinfection Cost, rf/K Gal 7.31 4.02 2.84
Ozone Generated from Oxygen
Capital Cost, $ 160,000 700,000 4,210,000
Disinfection Cost, rf/K Gal 7.15 3.49 2.36
Ultra Violet (UV) Irradiation
General
Ultraviolet light is a germicide that is absorbed by organic molecular
components essential for the cell's biological functioning. The excitation
of the molecules causes disruption of unsaturated bonds that produces a pro-
gressive lethal biochemical change. For most species, the bactericidal effect
31
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is a function of wave length and is greatest between 2500 and 2600 ang-
stroms (A). With the advent of low-pressure mercury lamps approximately
85% of the lamp's energy is emitted at 2537 A (19).
For UV to be an effective germicide, the energy dosage must reach the
organism. Some of the factors that may effect the penetration of UV energy
into water are turbidity, color and organic compounds.
Status
UV is used as a disinfectant for dimineralized water systems. It is
used for disinfecting potable water systems in overseas hotel, cruise ships
restaurants and vacation camps. There are many industrial and product water
applications that use UV, such as breweries, pharmaceutical manufacturers,
and fish hatcheries (20).
UV has not been studied extensively as a disinfectant for wastewater;
however, its feasibility was demonstrated at 40,000 GPD at St. Michaels, MD
(21). Its reliability was highly dependant upon effluent quality. Additional
research is required to establish minimum pretreatment requirements to opti-
mize design parameters, such as UV dosage, hydraulics, contact time and energy
requirements.
There is under construction a 2 MGD treatment plant with UV disinfection
at a new community development near Rochester, N.Y. As with ozone, the facility
will utilize filtration as a tertiary treatment stage prior to UV disinfection.
This system is scheduled to go on stream at minimum flows during the spring
of 1975. Chlorination facilities have been included at the site to serve as
a backup disinfection process.
Equipment
There are numerous suppliers of UV equipment which will ensure a compet-
itive market if UV surfaces as a viable alternative. The equipment manufac-
turers have made significant product improvements in regard to equipment,
maintenance, contact, and dosage. The manufacturers incorporate a continuous
UV monitor to measure transmission, which can serve as a parameter to monitor
the disinfection.
Safety
The operation of a UV system can produce ozone and safety precautions
covered under ozone may also be required for UV systems. The newer designs
of UV equipment have enclosed chambers to protect against aganinst irradi-
ation exposure which can be harmful to the eyes and skin.
32
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Reliability
The small plant study at St. Michaels, Md. showed that good quality
effluent could be disinfected with UV, however, tertiary treatment may be
required to provide adequate disinfection whenever the effluent is high in
solids or turbidity. Additional research is needed to provide process and
cost optimization to ensure adequate disinfection with minimum treatment
stages.
Research
The EPA research program has initiated a study of UV at Dallas, Texas
to evaluate some of the latest equipment with various pretreatment stages
and to determine the most cost effective design combination. The facility
under construction near Rochester, N.Y. will be considered as a potential
demonstration site to establish cost for UV disinfection.
Costs
The estimated cost for disinfecting wastewater with UV is shown in
Table VI.
Table VI
Estimated Disinfection Costs with UV
Plant Size, MGD 1 10 100
Capital Cost, $ 71,000 360,000 1,780,000
Disinfection Cost, rf/K Gal 4.19 2.70 2.27
Bromine Chloride
General
Bromine chloride is a chemical disinfectant, and is similar to chlorine
in its germicidal qualities. One of its advantages is that bromamines, formed
as a reaction product of hypobromous acid with ammonia, are also effective
germicides. In fact, bromamines are far superior to chloramines in bacteri-
cidal and virucidal activity. In addition bromamines are less stable in water
and break down to form bromide salts (22).
33
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Status
Bromine chloride is the newest candidate in search of an alternate
disinfectant. Its applicability as a disinfectant has progressed rapidly
by the research activity of its manufacturers. The manufacturers have per-
formed bench scale feasibility studies on bromine chloride and moved rap-
idly into pilot plant evaluations, by joint funding with EPA on the bioassay
and disinfection study at Wyoming, Michigan. At the present time, there are
no bromine chloride facilities in operation nor are there any in the design
phase; however the State of Maryland is actively searching for a potential
site to demonstrate the effectiveness of bromine chloride as an alternate
to chlorine.
Equipment - Chemical Suppliers
Existing chlorination facilities would require only minor modifications
to convert from chlorine to bromine chloride.
There are three known manufacturers of bromine chloride. Each of the
three would actively promote bromine chloride for wastewater disinfection
if the product showed promise of replacing chlorine at specific locations.
Bromine chloride development as a disinfectant was initiated by Dow Chemi-
cal Co. when their marketing studies indicated that bromine would be avail-
able for other uses as the quantity of leaded gasoline decreases. Presently
55 to 60% of the bromine goes toward the production of ethylene dibromide
(EDB), a lead scavenger in leaded gasoline. Recent studies indicate that
the decay in EDB demand amounts to 5% a year. We may assume that BrCl sup-
plies are limited now and will be limited in the near future. According to
the manufacturer, "Requests for the chemical will be handled on an individual
basis."
Safety
Bromine chloride requires the same care in handling as chlorine. As
such the same precautions that are used in shipping, handling, and storing
chlorine are required for bromine chloride.
Reliability
The pilot plant work at Wyoming, Michigan, has shown that bromine chlor-
ide is an effective disinfectant requiring no pretreatment for an activated
sludge effluent. Bromine chloride can accomplish the same degree of disin-
fection as chlorine with a lower final halogen residual, but the minimum
level has not been established.
34
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Research
Additional research is required to optimize bromine chloride contact
systems and to establish a minimum effective halogen residual. The toxicity
of brominated organic compounds is generally greater than the corresponding
chlorine compounds and additional studies will be required to determine the
health effect consequences. Since its chemical behavior is similar to chlor-
ine, its development has progressed more rapidly than other alternatives. To
take advantage of the potential for lower halogen residuals, instruments need
to be developed to ensure adequate monitoring of the effluent. Because of the
potential commercial applicability of bromine chloride, the manufacturers have
made a major contribution to its accelerated development.
Costs
The cost of disinfecting wastewater with bromine-chloride is shown in
Table VII. A cost summary is shown in Table VII listing the disinfectants
with their capital and total disinfection costs.
Table VII
Bromine Choride Disinfection Cost (7)
Plant Size, MGD 1 10 100
Capital Cost, $ 47,000 129,000 414,000
Disinfection Cost, tf/K Gal 4.52 3.04 2.65
OTHER POTENTIAL DISINFECTANTS
Chlorine Dioxide
Chlorine dioxide (ClO^) is one of the newer halogen disinfectants that
has shown promise for use in water and wastewater treatment. It is a power-
ful oxidizing agent and an excellent disinfectant.
Chlorine dioxide is unstable and extremely corrosive. In practice, it
is usually generated from the redaction between sodium chorite solution and
chlorine in contact with the water to assure that the gas remains in solution
to avoid explosion hazard. Sodium chlorite (NaCIO), from which the gas is
usually generated, is also explosive and the hazards of handling chlorine have
already been listed. Proper handling minimizes these hazards but responsible
personnel are required where it is used.
35
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The lack of an adequate method for accurately determining low residual
concentrations of chlorine dioxide is a serious drawback. Because it is such
a strong oxidizing agent, more C102 than chlorine may be required to disinfect
wastewater.
Factors other than the cost of the chemicals used may govern the expense
of wastewater treatment. Here, however, only cost of materials is considered.
The cost of NaClOs and Cl2 required to produce one pound of C102 is about 13
times more than one pound of Cl2.
Lime at pH 11.0 or Higher
It is unlikely tha lime would be seriously considered for disinfection only.
However, lime has pronounced potential for combined treatment and disinfection
of wastewater.
Results from EPA sponsored studies under Grant No. 16100 PAK, "Lime Dis-
infection of Bacteria at Low Temperature," are indicative of the effectiveness
of lime as a disinfectant. Even in the presence of relatively high concentra-
tions of organic matter and under the adverse conditions of low temperature
sewage can be disinfected to a safe level by lime treatment of pH 11.5 or 12.0.
A variety of generic types of bacteria can be destroyed during lime treatment
as evidenced by the large reductions in total and fecal coliform content of
both the effluent and the sludge. The process of disinfection can be completed
within a relatively short time period (30 minutes or less), even at 1° C. Addi-
tional benefits that can be realized from lime treatment are reduction in organic
materials and phosphorus. If the removal of organic chemicals and phosphorus
is not necessary, the cost of disposing of the sludge resulting from lime treat-
ment would have to be considered as part of the disinfection cost.
Bromi ne
Bromine is a liquid at atmospheric pressure and is safer to handle than
chlorine. It produces fumes which are very irritating and the liquid causes
severe burns. It is a good germicidal agent and effective tests are available
for determining residual concentration. As with chlorine, the amine form is
produced when ammonia is present, and the breakpoint phenomenon has been dem-
onstrated. Bromine, hypobromous acid (HOBr), and monobromamine are considered
nearly equal in bactericidal properties and essentially equal to free- chlorine
at comparable pH. Some of the advantages give for using bromine are: (a) it
is easier to feed and not as hazardous to store as chlorine; and (b) the bac-
tericidal efficiency of bromamines is much greater than that of chloramines.
Data accumulated on an EPA sponsored Grant No. 17060 DNU by the Illinois Water
Survey Laboratory indicate that the effectiveness of chlorine decreases with
increasing pH, whereas bromine is most effective at high pH. This indicates)
potential for use with effluents subjected to phosphate removal with lime or
ammonia stripping where the effluents have high pH. Possible potential for
combing bromine and chlorine for disinfection was indicated. Cost-wise liquid
bromine costs approximately 3.5 times more than chlorine.
36
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Iodine
Commercial iodine is a nonmetallic solid. It is usually referred to as
"metallic" iodine and has the appearance of dark, shiny, thin pieces of metal.
In this form it is corrosive and ordinary metal containers are unsuitable for
shipment or storage. It is dense and sublimes slowly at room temperatures.
The hazards due to toxic vapors of iodine are less than the other halogens
considered for disinfection of water or wastewater. The vapor pressure of
iodine at 25o C is only 0.31 mm Hg. The corresponding figures for bromine
and chlorine are 215 and 5,300 mm Hg respectively. Iodine is not considered
to form iodamines under conditions prevailing in wastewater and organic demand
may be less of a problem than with chlorine and bromine. Plant treatment of
large volumes of wastewater with iodine would not ordinarily be economically
feasible because it is significantly more expensive than chlorine, in terms
of cost per unity of germicidal effectiveness. It primary potential may be
for use in arctic fly-in outpost settlements where it can be shipped in light
weight cardboard cartons. The cost of disinfecting with iodine is roughly 18
times more than the cost of an equivalent amount of chlorine. While some re-
duction in dosage with iodine might be considered becasue of probable increased
persistence of the germicidal residual, the economics are strongly against the
use of iodine as a substitute for chlorine except under circumstances where
cost is a secondary consideration.
Ionizing Radiation
Ionizing radiation has been studied extensively as a potential sterilizing
agent for foods. Its use as a disinfectant of wastewater effluents, either
alone or in combination with another disinfectant, has been suggested in the
literature. Its potential advantages include: (a) greater penetrating power
than other forms of radiation, such as ultraviolet light; (b) no residual pro-
duced in the effluent stream; (c) capability of initiating oxidation of organic
molecules and refractory pollutants.
The sources of high energy radiation are cobalt-60, cesium-137, electron
accelerators, reactor loops, fuel elements, and mixed fission products. Each
must be analyzed in terms of costs, availability, characteristics, and install-
ation requirements. All radiation devices require special shielding and handling
facilities, constant monitoring of radiation areas, keeping of personnel expo-
sure records, etc. The electron, accelerator facility requires electric power
for operation. Due to the dearth of information relative to the practicality
of any of these radiation sources, only rough cost estimates have been made.
A recent study investigating the combined bactericidal effect of cobalt-60
gamma radiation and monochloramine on aqueous suspension of Escherichia coli
indicates at most an additive effect. Thus, unless a significant synergistic
effect can be demonstrated when radiation is used in combination with another
disinfectant, radiation disinfection costs appear prohibitive for general waste-
water treatment.
37
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Low pH as a Disinfectant
Exposure of microoganisms to extremes in hydrogen ion concentration
is a relatively ineffective method of disinfection. It is known that
Escherichia coli can withstand a pH 1-2 environment for one hour with only
a 75-80% loss in viability. Salmonella typhosa is somewhat more sensitive.
A pH value of 4-5 is ineffective in reducing the viable count of these organ-
isms. These statements are further substantiated when one considers that
enteric bacteria must survive the extreme acid pH of the stomach before enter-
ing the small intestine. Thus, for low pH to be a truly effective disinfectant,
extreme acidity must persist for a considerable period of time.
38
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PLANT SIZE, MGD
CAPITAL COST
PROCESS
Chlorine
Chlorine/S02
Chiorine/S02/Aeration
Chlorine/Carbon
Ozone/Air*
Ozone/Oxygen*
Ultraviolet*
Bromine Chloride
TABLE VIII
COST SUMMARY
1
$K
10
100
$K
60
70
120
640
190
160
70
50
190
220
360
2,800
1,070
700
360
130
840
930
1,580
8,400
6,880
4,210
1,780
410
Activated Sludge
DISINFECTION COST
PROCESS
Chlorine
Chlorine/S02
Chlorine/S02/Aeration
Chlorine/Carbon
Ozone/Air
Ozone/Oxygen*
Ultraviolet*
Bromine Chloride
1,450
iflKGal
3.49
4.37
7.66
19.00
7.31
7.15
4.19
4.52
5,790 39,800
rf/KGal. tf/KGal
1.42
1.75
2.39
8.60
4.02
3.49
2.70
3.04
0.70
0.89
1.19
3.28
2.84
2.36
2.27
2.65
Activated Sludge 55.90 20.20 14.00
* Tertiary treatment stage is not included in these costs.
39
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TABLE IX
SUMMARY ON THE STATUS OF DISINFECTANTS
Chlorine
Sodium Hypochlorite
Chlorine/Sulfur Dioxide
Chlorine/Carbon
Ozone/Ai r
Ozone/Oxygen
Ultraviolet
Bromine Chloride
State-of
the-Art
Energy
KWH/MG
Operational 90
Operational 280
Operational 90
Pilot Plant
Pilot Plant
Pilot Plant
Pilot Plant
Pilot Plant 90
Health
Effects
Assume
Chlorinated
Organics
Assume
Chlorinated
Organics
Assume
Chlorinated
Organics
Halogenated
Organics
Aquatic
Toxic
Effects
High
High
Low
no
800
400
350
Assume
Minimal
Unknown
Unknown
Assume
Minimal
Low
Low
Low
Assume
Low
Intermediate
40
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APPENDIX A - RESEARCH AND DEVELOPMENT PROJECTS
Listed below are brief descriptions of EPA research projects on
disinfection.
On Going Projects
A. "Parallel Ozonation and Chlorination with Dechlorination of
Chlorinated Effluent." Project No. 802292, City of Wyoming.
A study on disinfection effectivenss and bioassay effects of
chlorine, ozone, dechlorination with suflur dioxide and bromine
chloride. Estimated completion date, Jan. 1976.
B. "Ultraviolet Disinfection of Municipal Effluents", Project No.
803292, City of Dallas.
The evaluation of ultraviolet light as a disinfectant for
wastewater.
C. "Reduction of Toxicity Emission Rates from Wastewater Treatment
Plants by Optimization of the Chlorination Process." Project No.
803459, State of California.
Develop cost effective design parameters for the Chlorination
process.
D. "Multicell Lagoons - Micro Organism Removal Efficiency arid Effluent
Disinfection", Project No. 803294, Utah State University.
Define the lagoon equivalency to disinfection and determine
whether Chlorination will affect the organic content of effluent.
E. "A Comparative Study of the Inactivation of Viruses in Waste,
Renovated and Other Waters by Chlorine and Chlorine Compounds".
Project No. 800370, University of Cincinnati.
Determine the capability of chlorine and chlorinated com-
pounds to destroy viruses in wastewaters.
F. "New Microbial Indicators of Wastewater Chlorination Efficiency",
Project No. 800712, University of Illinois.
Develop a biological indicator that is more suitable and reli-
able than the coliform group. Report No. EPA 670/2-73-082.
6. "Ozone Contactor Study", AWTRL Pilot Plant,
An evaluation of ozone contactor efficiencies.
41
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II. Completed Projects
A. "The Detection and Inactivation of Enteric Viruses in Waste-
water", Project No. 800990, Hebrew University.
Develop effective and economical procedures for the in-
activation of viruses in wastewater by ozone.
B. "Batch Disinfection of Treated Wastewater with Chlorine at
Less Than 1 C," Project 16100 GKG, Arctic Environmental
Research Laboratory, Report No. EPA-660/2-73-005.
C. "Lime Disinfection of Sewage Bacteria at Low Temperature",
Project 16100 PAK, Colorado State University, Report No.
EPA-660/73-017.
D. "Hypochlorite Generator for Treatment of Combined Sewer
Overflows", Report No. 110233 DAA 03/72, Ionics Incorpor-
ated.
E. "Ultraviolet Disinfection of Activated Sludge Effluent Dis-
charging to Shellfish Waters", Project No. WPRD 139-01-68,
The Town of St. Michaels.
F. "Disinfection of Sewage Effluents", Project No. 17060 DNV
University of Illinois, Bromine and Chlorine Disinfection
Results.
G. "Demonstrate Effectiveness of Iodine for the Disinfection
of Public Water Supplies", Project No. 19-06-68, City of
Gainesville.
H. "Hypochlorination of Polluted Stormwater Pumpage at New
Orleans", Report No. EPA-670/2-73-067, Pavia-Byrne
Engineering Corporation, New Orleans, La.
I. "Bench-Scale High-Rate Disinfection of Combined Sewer Over-
flows with Chlorine and Chlorine Dioxide", Project No.
802400, O'Brien and Gere Engineers, Inc. Syracuse, New York.
42
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APPENDIX B - STATE STANDARDS (EXISTING)
A. Water Quality
- Coliform limitations based on stream use of basin designation:
all States except Nevada.
- Seasonally or hydrographically based: 9 States.
- General toxicity standard applied thru permits: 9 States.
- Maximum chlorine residual standard applied thru permits: 6 States.
- State maximum chlorine residual limitations: 3 States.
B. Disinfection
- Year-round disinfection: 21 States.
- Universal disinfection with case-by-case exception: 1 State.
- Case-by-case disinfection requirements: 19 States.
- No specific requirements: 1 State.
- Secondary treatment - no specific disinfection requirement: 19 States.
- No standards: 8 States.
- Minimum chlorine residual: 5 States.
43
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APPENDIX C
TABLE I. Tentative Indentification and Concentrations of Chlorine-
Containing Constituents in Chlorinated Effluents
Concentration of
Organic Compound
Identification (ug/liter)
5-Chlorouracil 4.3
5-Chlorouridine 1.7
8-Chlorocaffei ne 1.7
6-Chloroguanine 0.9
8-Chloroxanthine 1.5
2-Chlorobenzoic acid 0.26
5-Chlorosalicylic acid 0.24
4-Chloromadnelic acid 1.1
2-Chlorophenol 1.7
4-Chlorophenylacetic acid 0.38
4-Chlorobenzoic acid 1.1
4-Chlorophenol 0.69
3-Chlorobenzoic acid 0.62
3-Chlorphenol 0.51
4-Chlororesorcinol 1.2
3-Chloro-4-hydroxy-benzoic acid 1.3
4-Chloro-3-methyl-phenol 1.5
44
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TABLE II. Organochlorine Compounds in Water from Sewage Treatment Plants
Influent
before
Compound3 Treatment
Concentration (ug/1)
Effluent Effluent
before after
Chl ori nation Chl ori nation
Methylene chloride
Chloroform
1 ,1 ,1-Trichloroethane
1 ,1 ,2-Trichloroethylene
1 ,1 ,2,2-Tetrachloroethylene
Dichlorobenzenes
Tri chl orobenzenes
8.2
9.3
16.5
40.4
6.2
10.6
66.9
2.9
7.1
9.0
8.6
3.9
5.6
56.7
3.4
12.1
8.5
9.8
4.2
6.3
56.9
confirmed by GC-MS
45
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TABLE III. Trihalogenated Methane Content of Water from Water Treatment
Plant
Sample Source • Sampling
Point
Concentration (ug/1 )
Free Bromo Dibromo-
Chlorine Chloro- dichloro- chloro-
ppm form methane methane
Raw river water 1
River water treated 2
with chlorine and alum-
chlorine contact time
80 min.
3-day-old settled water 3
Water flowing from 4
settled areas to filters^
Filter effluent 5
Finished water 6
0.0 0.9 a a
6 22.1 6.3 0.7
2 60.8 18.0 1.1
2.2 127 21.9 2.4
Unknown 83.9 18.0 1.7
1.75 94.0 20.8 2.0
aNone detected. If present, the concentration is less than 0.1 ug/1.
bCarbon slurry added at this point.
46
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TABLE IV
.SOME RECOGNIZED AND SUSPECT CARCINOGENS FOUND
IN MUNICIPAL WATER SUPPLIES
CHEMICAL ASSOCIATED WATERWAY
Bis (2-Chloroethyl) Ether Ohio River
Chlorodibromomethane Ohio River
Bromoform Ohio River
Benzene Ohio River and Wabash River
Carbon TetrachlorideR Ohio River
Bis Chioromethyl EtherR* Ohio River
Chloromethyl Methyl EtherR Ohio River
Choromethyl Ethyl Ether Ohio River
R = recognized carcinogen
* = decomposes readily
47
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TABLE V. Halo-organic Compounds Identified in Drinking Waters in the
United States (as of 11/25/74)
1. acetylene dichloride
2. aldrin
3. atrazine
4. (deethyl) atrazine
5. bromobenzene
6. bromochlorobenzene
7. bromodichloromethane
8. bromoform
9. bromoform butanal
10. bromophenyl phenyl ether
11. carbon tetrachloride
12. chlordan (e)
13. chlorobenzene
14. chlorodibromomethane
15. 1,2-bis-chloroethoxy ethane
16. chloroethoxy ether
17. bis-2-chloroethyl ether
18. b-chloroethyl methyl ether
19. chloroform
20. chlorohydroxy benzophenone
21. bis-chloroisopropyl ether
22. chloromethyl ether
23. chloromethyl ethyl ether
24. m-chloronitrobenzene
25. 3-chloropyridine
26. DDE
27. DDT
28. dibromobenzene
29. dibromochloromethane
30. dibromodichioroethane
31. 1,4-dichlorobenzene
32. dichlorodifluoroethane
33. 1,2-dichlorobenzene
34. dichloroethyl ether
35. dichloromethane
36. dieldrin
37. heptachlor
38. heptachlor epoxide
39. 1,2,3,4,5,6,7,7-heptachloronorbornene
40. hexachlorobenzene
41. hexachloro-1,3-butadiene
42. hexachlorocyclohexane
43. hexachloroethane
48
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TABLE V (cont.)
44. methyl chloride
45. octyl chloride
46. pentachlorobiphenyl
47. pentachlorophenol
48. 1,1,3,3-tetrachloroacetone
49. tetrachlorobiphenyl
50. tetrachloroethane
51. tetrachloroethylene
52. trichlorobenzene
53. trichlorobiphenyl
54. 1,1,2-trichloroethane
55. 1,1,2-trichloroethylene
56. trichlorofluoromethane
57. 2,4,6-trichlorophenol
49
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CHLORINE ALUM
SETTLED WATER
AVERAGE AGE -
3 DAYS
*— CHLORINE
CARBON SLURRY
FILTER
CHLORINE
- FINISHED WATER
INDICATES
SAMPLING POINT
Figure i. WATER TREATMENT PLANT SAMPLING POINTS
50
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APPENDIX D
SECTION IV REFERENCES
1. Geldreich, E.E., "Water Borne Pathogens in Water Pollution Micro-
biology ed R. Mitchel, Wiley-Interscience, New York, 1972 p. 207-235.
2. Flynn, M.J. and Thistlewayte, D.K.B., "Sewage Pollution and Sea
Bathing", Second International Conference on Water Pollution Research,
1964.
3. Morbidity and Motality Weekly Report. "Shigellosis Associated with
Swimming in the Mississippi River", National Center for Communicable
Disease, U.S.D.H.E.W., Vol. 23, No. 46, 1974.
4. Ibid. Morbidity arid Mortality Weekly Reports. "Hepatitis in Camps -
Florida". National Center for Communicable Diseases, U.S.D.H.E.W.,
Vol. 20, No. 26, 1971.
5. Jones, E.H. "External Otitis, Diagnosis and Treatment", C.C. Thomas
Publications, Springfield, Illinois, 1965.
6. Fisher, L.M., 1937, "Report of the Committee on Shellfish", Public
Health Engineering Section, American Public Health Association, Am.
J. Publ. Hlth 27:180-196, Supplement March 1973.
7. Mosely, J.W., "Epidemiological Aspects of Microbial Standards for
Bathing Beaches", International Symposium on Discharge of Sewage
from Sea Outfalls, London, England, August 1974, Paper No. 9.
8. National Shellfish Sanitation Program Manual of Operations. Part I,
Sanitation of Growing Areas, U.S. Department of Health, Education
and Welfare, Shellfish Sanitation Branch, Washington, D.C., 1965,
p. 36.
9. Hunt, D.A. and Springer, J. 1975, Preliminary Report on A Compar-
ison of Total Coliform and Fecal Coliform Values in Shellfish Growing
Areas and a Proposed Fecal Coliform Growing Area Standard." Pre-
sented at the 8th National Shellfish Sanitation Workshop, F.D.A.,
Washington, D.C.
10. National Technical Advisory Committee, Water Quality Criteria, Fed-
eral Water Pollution Control Administration, Department of Interior
Washington, D.C., 1968, pp. 7-14.
11. Cabelli, V.J., M.A. Levin, Dufour, A.P. and McCabe, L.J. "The
Development of Criteria for Recreational Waters" International
Symposium on Discharge of Sewage from Sea Outfalls, London, England,
August 1974, Paper No. 7.
51
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12. National Academy of Sciences, "Water Quality Criteria 1972",
Washington, D.C.
13. Lui, 0. and McGowan, F., Northeastern U.S. Water Supply Study
Potomac Estuary Water Supply: A Consideration of Viruses, U.S.
Army Eng. Div., N. Atlantic, 1970.
14. Chambers, C.W., 1971, "Chlorination for Control of Bacteria and
Viruses in Treatment Plant Effluents", Jl. Water Pollution Control.
Federation. 43:228-241.
15. Scarpino, P.V., "Human Enteric Viruses and Bacteriophages as
Indicators of Sewage Pollution", International Symposium on Dis-
charge of Sewage from Sea Outfalls, London, England, August 1974,
Paper No. 6.
16. Chang, C.M., Boyle, W.C. and Goepfent, J.M., "Rapid Quantitative
Method of Salmonella Detection in Polluted Waters", Applied Micro-
biol. 1971, 21:662.
17. Merrell, J.C. et^ al_. 1967, "The Sante Recreation Project", Sante
California, F.W.P.C.A., D.I., WP - 20-7.
18. Velz, Calrence J., "Applied Stream Sanitation", Wiley-Interscience,
New York, 1970, p. 17.
19. Jackson, S., 1974, "Disinfection of Secondary Effluent with Bromine
Chloride", Workshop on Disinfection of Wastewater and its Effect
on Aquatic Life", Grand Rapids, Michigan.
20. Rosen, H.M., Lawther, F.E. and Clark, R.G., 1974, "Getting Ready
for Ozone", Water and Waste Eng. ll(Jul):25.
21. Kelly, S. and Sanderson, W.W., 1960, "The Effect of Combined Chlorine
on Poliomyelitis and Coxachie Viruses", A.J.P.H. 50:14.
22. Clarke, N.A. et. al_. 1964, "Human Enteric Viruses in Water", Source
Survival and Removability in: Adv. Water Pollution Res. Vol. 2.,
McMillan, New York.
23. Shuval, H.I. ejt al_. 1966, " The Inactivation of Enteric Viruses in
Sewage by Chlorination in : Adv. Water Pollution Res., Vol. 4,
McMillan, New York.
24. Craun, F.G. and McCabe, J.L. "Review of the Causes of Waterborne
Disease Outbreaks", JAWWA 65, 74 (1973).
52
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25. Craun, F.G. and McCabe, J.L. "Outbreaks of Waterborne Disease in
the United States", 1971-1972, The Journal of Infectious Diseases,
Vol. 129, 614, May 1974.
26. Mason, J.O., and McLean, W.R., 1962, "Infectious Hepatitis Traced
to The Consumption of Raw Oysters", AM. J. Hyg. 75_:90-111.
27. Pameroy, R.D., "Empirical Approach for Determining Required Length
of an Ocean Outfall", Proc. 1st. Int. Conf. Waste Disposal Mar. Env.
Pergamon Press, London, 1960, pp. 268-278.
28. Gunnerson, C.G. "Discharge of Sewage from Sea Outfalls", London,
August 1974, Paper No. 41.
29. Pearson, E.A., "Conceptual Design of Marine Waste Disposal System",
Int. Symp. on Discharge of Sewage from Sea Outfall, London, August
1974, Paper No. 40.
30. Cabelli, V., EPA National Marine Water Quality Laboratory, Narragan-
sett, R.I., Personal Communication.
31. Jolly, R.W., "Chlorination Effects on Organic Constituents in Effluents
from Domestic Sanitary Sewage Treatment Plants", Oak Ridge National
Laboratory, October, 1973.
32. Ajami, A.M., "Review of the Environmental Impact of Chlorination and
Ozonation By-products", Eco-Control, Inc., Cambridge, Mass., June,
1974.
33. Bellar, T.A., Lichtenberg, J.H. and Kroner, C.R., " The Occurrence
of Organohalides in Chlorinated Drinking Waters", EPA-670/4-74-008,
November, 1974.
34. Rook, J.J., "Formation of Haloforms During Chlorination of Natural
Waters", The Journal of the Society for Water Treatment and Examina-
tion, Vol. 23, part 2, p. 234 (1974).
35. Kraybill, H.F., "The Distribution of Chemical Carcinogens in Aquatic
Environments", National Cancer Institute, October, 1974.
36. Little, A.D. Inc., Cambridge, Mass., "Organic Chemical Pollution of
Freshwaster", EPA #18010 DPV 12/70.
37. McCabe, L. and Tardiff, R., Derived from a Paper presented before
the DHEW Committee to Coordinate Toxicology and Related Programs,
November, 1974.
53
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38. Snoeyink, V.L. ejt al_. "Active Carbon: Dechlorination and the Adsorption
of Organic Compounds", Chemistry of Water Treatment and Distribution,
A.J. Rubin, Ed., Ann Arbor Science, 1974.
39. Fair-, G.M. and Geyer, J.C., "Water Supply and Waste-Water Disposal",
John Wiley and Sons, 1954.
54
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SECTION V - REFERENCES
1. Merkens, J.C., "Studies on the Toxicity of Chlorine and Chloramines
to the Rainbow Trout". Water and Waste Trt. Jour. (G.B.), 7, 150 (1958).
2. Doudoroff, P., and katz, M., "Critical Review of Literature on the
Toxicity of Industrial Wastes and Their Components to Fish". Sew. and
Ind. Wastes, 22, 1432 (1950).
3. "Chlorinated Municipal Waste Toxicities to Rainbow Trout and Fathead
Minnows". Mich. Dept. of Natural Resources, Water Pollution Control Res.
Ser., 18050 GZ2, EPA, Washington, D.C. (1971).
4. Tsai, C., "Water Quality and Fish Life Below Sewage Outfalls". Trans.
Amer. Fish. Soc., 102, 281 (1973).
5. Arthur, J.W., et^ a\_., "Comparative Toxicity of Sewage-Effluent Dis-
infection to Freshwater Aquatic Life". Water Poll. Control Res. Ser.
EPA, Washington, D.C. (1975).
6. Esvelt, L.A., ejt aj_., "Toxicity and Removal from Municipal Wastewaters".
Vol. IV, "A Study of Toxicity and Biostimulation in San Francisco Bay-
Delta Waters". SERL Rep. No. 71-7, San Eng. Res. Lab., Univ. of
California, Berkeley (1971).
7. Esvelt, LA., et^ aj_., "Toxicity Assessment of Treated Municipal Waste-
water". Jour. Water Poll. Control Fed., 45, 1558 (1973).
8. Krock, H., and Mason, D.T., "Bioassay of Lower Trophic Levels". Vol VI,
"A Study of Toxicity and Biostimulation in San Francisco Bay-Delta
Waters". SERL Rept. No. 71-8, San Eng. Res. Lab., Univ. of California,
Berkeley (1971).
9. Martens, D.W., and Serviat, J.A., "Acute Toxicity of Municipal Sewage
to Fingerling Sockeye Salmon". International Pacific Salmon Fisheries
Commission Progress Report No. 29, New Westminster, B.C. 18 p (1974).
10. Servizi, J.A. and Martens, Ej.W., "Preliminary Survey of Toxicity of
Chlorinated Sewage to Sockeye and Pink Salmon". International Pacific
Salmon Fisheries Commission Progress Report No. 30, New Westminster,
B.C. 42 p (1974).
11. Enoeyink, V.L., and Markus, F.I., "Chlorine Residuals in Treated Effluents",
Water adn Sewage Works, 121, 35 (1974).
12. McKersie, J., "A Study t)f Residual Chlorine below Selected Sewage Treat-
ment Plants in Wisconsin, Summer, 1974". Wise. Dept. of Nat. Res.
Water Quality Evaluation Section, Mimeo 18 p (1974).
55
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13. Nebel, C., ejt aj_., "Ozone Disinfection of Industrial-Municipal Secon-
dary Effluents." Jour. Water Poll. Control Fed. 45, (1973).
14. Holland, G.A. ejt al_., "Toxic Effects of Organic Pollutants on Young
Salmon and Trout". Wash. Dept. Fish., Res. Bull. No. 5. 260 p
(1960).
15. Alderson, R., "Effects of Low Concentrations of Free Chlorine On
Eggs and Larvae of Plaice, Pleutonectes platessa L." In: Marine Pol-
lution and Sea Life. Fishing News, Ltd., London pp 312-315 (1972).
16. Muchmore, D. and D. Epel., "The Effects of Chi orination of Waste-
water on Fertilization in Some Marine Invertebrates". Mar. Biol.
19:93-95 (1973).
17. Galtsoff, P.S., "Reactions of Oysters to Chiorination". USFWS. Res.
Rpt. 11 (1946).
18. Tsai, C., "Effects of Chlorinated Sewage Effluents on Fishes in Upper
Patuxent River, Maryland". Chesapeake Sci. 9:83-93 (1968).
19. Tsai, C., "Changes in Fish Populations and Migration in Relation to
Increased Sewage Pollution in Little Patuxent River, Maryland". Ches-
apeake Sci. 11:34-41 (1970).
20. Waugh, G.D., "Observations on the Effects of Chlorine on the Larvae
of Oysters, Ostrea edulis L., and Barnacles Elminius modestus, Dar-
win". Ann. Appl. Biol. 54:423-440 (1964).
21. McLean, R.I., "Chlorine and Temperature Stress in Estuarine Inver-
tebrates". Jour. WPCF. 45:837-841 (1973).
22. Carpenter, E.J., B.B. Peck and S. J. Anderson, "Cooling Water Chlor-
ination and Productivity of Entrained Phytoplankton". Mar. Biol.
16:37-40 (1972).
23. Hirayama, K. and R. Hirano, "Influences of High Temperature and Residual
Chlorine on Marine Phytoplankton". Mar. Biol. 7:205-213 (1970).
24. Gentile, J.H., J. Cardin, M. Johnson and S. Sosnowski. "The Effects
of Chlorine on the Growth and Survival of Selected Species of Estuarine
Phytoplankton and Zooplankton". Unpublished Manuscript (1972).
56
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25. Gentile, J. H., S. Cheer and N. Lackie, "The Use of ATP in the
Evaluation of Entrainment." Unpublished Manuscript (1973).
26. Basch, R. E., and Truchan, J. G., "Calculated Residual Chlorine
Concentrations for Fish." Michigan Water Resources Commission,
Lansing, Michigan 29 p (1974).
27. EIFAC, "Report on Chlorine and Freshwater Fish." European Inland
Fisheries Advisory Commission Technical Paper No. 20, Food and
Agriculture Organization of the United States, 11 p (1973).
28. Brungs, W. A., "Effects of Residuals Chlorine on Aquatice Life."
Jour. Water Poll. Control Fed. 45, 2180 (1973).
57
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SECTION VI REFERENCES
1. "Summary Report: The Extent of Shortages for Chlorine and Other
Water Sanitation Chemicals". U.S. Environmental Protection Agency
(April 1974).
2. "Chlorine - Its Manufacture Properties and Uses". J.S. Sconce (Ed)
American Chemical Society Monograph Series No. 154 Reinhold Pub. Corp.,
New York (1962).
3. Brezenski, F.T., e_t aj_, "The Occurrence of Salmonella and Shingella in
Post-Chlorinated and Non-Chlorinated Sewage Effluents and Receiving
Waters". Health Lab. Sci., 2., 40 (1965).
4. Chambers, C.W., "Chiorination for Control of Bacteria and Viruses in
Treatment Plant Effluents" Jour. Water Poll. Control Fed., 43_, 230
(1971).
5. Scarpino, P.V., et al, "Destruction of Viruses and Bacteria in Water
by Monochlorimine71" In Press, Proc. 7th Intnl. Conf. Water Poll. Res.
Pergamon Press, Paris, France.
6. Scarpino, P.V., et^ aj_, "A Comparative Study of the Inactivated of
Viruses in Water by Chlorine" Water Res. (G.B.) 6_, 959 (1972).
7. Smith, R., et_ aj_, "Cost of Alternative Processes for Wastewater Dis-
infection" Presented - Workshop on Disinfection of Wastewater and
Its Effect on Aquatic Life, Wyoming, Michigan. (Oct. 1974).
8. "Disinfection of Wastewater with Sodium Hypochlorite" Chapter VII,
(Author - T. Kennedy - Chicago Metro. Sanitary District) Manual of
Practice for Chiorination of Wastewater, Water Poll. Control Fed.
In press.
9. Baker, R.J., "Characteristics of Chlorine Compounds" Jour. Water Poll.
Control Fed., 41482 (1969).
10. Baker, R.J. (Wallace and Tiernan Co. - Belleville N.J.) Personal
Communication (Jan. 2, 1975).
11. White, George Clifford, "Handbook of Chlorination" Van Nostrand-Reinhold
New York (1972).
12. Personal Communication to: W. McMichael, AWTRL, NERC-Cincinnati
(oct. 1974).
58
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13. "Process Design Manual for Carbon Adsorption". Environmental
Protection Agency, Technology Transfer, October 1973.
14. Collins, H.F. ejt al_ "Interim Manual for Wastewater Chlorination
and Dechlorination Practices", California State Department of
Health, February, 1974.
15. "Ammonia Removal in a Physical-Chemical Wastewater Treatment
Process, Environmental Protection Agency, No. EPA-R2-72-123,
November 1972.
16. Lee, J.S. et^ al_, "Ozonation as an Alternative to Chlorination for
the Disinfection of Treated Wastewaters, Metropolitan Sewer Board
of the Twin Cities, October, 1973.
17. Mittler, S. e£ al_, "Toxicity of Ozone", Ozone Chemistry and Technology
American Chemical Society, Washington, D.C. 1959, pp. 344-351.
18. Greening, E. "Feasibility of Ozone Disinfection of Secondary Effluent",
Illinois Institute for Environmental Quality, IIEQ No. 74-3, January,
1974.
19. Huff, C.B. ejt aj_, "Study of Ultraviolet Disinfection of Water and
Factors in Treatment Efficiency", Public Health Reports, August 1965,
volume 80, number 8, pp 695-705.
20. "Facts You Should Know About Ultradynamics", Brochure by Ultradynamics
Corporation, Patterson, N.J.
21. "Ultraviolet Disinfection of Activated Sludge Effluent Discharging to
Shellfish Waters", Draft Report, Project WPRD 134-01-68.
22. Filbrey, A.H., "Bromine Chloride as an Alternate Disinfectant" Chlorine
Residual Policy Seminar, State of Maryland, November 1974.
23. Jackson, S.C. "Chiorobromination of Secondary Sewage Effluent", Dow
Chemical Company, December 1974.
24. Walkenhuth, E.C. et^ ail_, "An Investigation of Bromine Chloride as a
Biocide in Condenser Cooling Water, 35th Annual Meeting International
Water Conference, Pittsburgh, Pennsylvania, October 1974.
59
•&U.S. GOVERNMENT PRINTING OFFICE: 1976-678-102/356 REGION NO. S
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