DISINFECTION
OF
WASTEWATER
TASK FORCE REPORT
JULY 1975
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Reasearch and Development
Washington, D.C. 20460
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TASK FORCE REPORT
DISINFECTION
of
WASTEWATER
ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
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SECTION 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. Opajtken
NERC, Cincinnati
Advanced Waste Treatment Research Laboratory
Cecil Chambers
Office of Environmental Science
Ecological Processes and Effects Division
Frank G. Wilkes
Water Supply Resiearch Division
Hend Gorchev
NERC, Corvallis
National Water Quality Laboratory, Duluth, Minnesota
William A. Brjungs
William P. Dalvis
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 Introduction 6
IV Public Health Effects 8
V Effects of Disinfectants on 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 lo develop the neces-
sary background information for consideration of ogency policy on wastewater
disinfection requirements and the use of chlorine. During that time the major
consideration of the Task Force.w.as. 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, ORU was requested by the Deputy Assistant Administrator
for Water Programs, OWPO, onDecemberS, 1S'74, to assume the responsibility
of completing the Task Force report. .
Objective of the Task Force
The main objective of ihcOHD Disinfection PC licy Task Force was to provide
information in the form of guidance on public he ilth 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 summajy report for use by the Office
of Water Programs Operations in dealing with thi 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 docs provide an effective means of
reducing to a sale 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 toxicity
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 cisiorination; Results have shown that dechlor-
ination is effective in reducing the toxic effects associated with resi-
dual combined chloriae.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 disinfection. 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 water uses.
2. Chlorine is currently the predominant wastewater disinfectant and it is
essentially the exclusive disinfectant if one includes its counterpart, sod-
ium hypochlorite. Disinfection of secondary effluents with chlorine .can
reliably meet the present bacteriological standards for secondary treat-
ment.
3. Disinfection of water and wastewater with chlorine can result in the forma-
tion of halogenated organic compounds that are potentially toxic to man.
4. Disinfection of wastewaters with chlorine can result in a residual chlorine
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, indicate that chlorine at concentrations
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 removing
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 tertiary 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 wastewater,
there is limited information that indicates it may become a potentially
desirable alternative. It is the only physical process whereas all the
other disinfectants are chemical processes. On-going research will pro-
vide 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 regula-
tions 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 down stream water supply,
recreation, 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 of public health is not involved addi-
tional flexibility should be allowed in the consideration of across the board
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 total residual chlorine in the receiving waters
should not exceed the recommended levels outside a described mixing
zone. Use of alternate processes 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 drink-
ing 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 Stales, 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 colitorm-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 National 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 FWQA1 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
alternatives and the necessary bioassay support work. Consistent with the
state-of-the-art at that time, emphasis was put on further developing the de-
chlorination and ozonation processes as the likely candidates that could supple-
ment 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 applications, 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 develop* d 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,
enteropathogenic Escherichia coli, Pseudomanas aeruginosa and a variety
of enteric viruses^including hepatitis (1)1 Furthermore, outbreaks of
gastroenteritis, typhoid, shigeilosis, salmonellosis. ear infections due to
Psendpmonas aeruginosa, and infectious hepatitis have been reported a-
mohg individuals drinking or swunming in sewage contaminated waters
or consuming raw molluscan shellfish harvested therefrom (2-7).
The range and densities of pathogens in municipal waste water effluents
are,, of course, dependent on the number of active cases and carriers
in the discharging 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 pre-
sence 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 probability 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 coli-
forms per 100 ml in shellfish growing waters (8,9). From a limited
quantity of epidemiological 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 recommenda-
tion 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 re-
moval or chemical destruction{disinfecticm)of the pathogens and indicator
microorganisms at the source or their dilution together with natural
die-away in transit to the target. Primary and secondary treatment sys-
tems were not designed for nor are they particularly effective in reducing
xnicrobial densities in wastewaters. Their effectiveness as reported in
the literature varies w-ith the organisms being studied, the type of treat-
ment and the operative conditons during the study (13-15). In general,
the combined effect of primary and secondary treatment does not reduce
pathogenic bacteria and viruses or indicator bacteria more than 90 per-
cent. However, the effectiveness of disinfection is enhanced by the re-
moval of solids and nutrients during treatment.
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Benefits of Disinfection
Chemical disinfection of waste-waters using chlorine is an effective
means of reducing the density of pathogenic and indicator bacteria provided
that solids and interfering materials are reduced by preliminary treat-
ment, residual chlorine levels are maintained and the contact time is
su fficiently long. Reductions of 99. 9 to 99 percent have been reported
with salmonellae and coliform bacteria (16, 17). Velz (18) notes that it
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 chlor-
ine, although the sensitivity varies considerably by species, type, and
even strain. 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 HOC1 In r2~ seconds. At the same concentra-
tion of hypochlorous acid, a 99 percent kill of poliovirus 1 and coxsackie
virus A2 were attained in 8 minutes and 40 minutes respectively. Shuval
et al. (23) in their study of the effects of 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 destruction 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 out-
breaks. 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 occurred each
year in the United States (24). However, for 1971 and 1972 the rate
has increased to an average of 24 outbreaks per yg'ar. Most common
causes of these outbreaks are: lack of disinfection of groundwater, break-
down of chlorination equipment, cross-connections (25).
In both the shigella (3) and salmonella (2) outbreaks of swimming as-
sociated 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). Therefore, it would seem that proper disinfection
superimposed on secondary or tertiary treatment does render waste water
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
indicator microorganisms when the receiving stream is used for water
supply recreation and shellfish growing areas.
Obviously, the above definition "is not fixedin concrete". As advanced
methods for pathogen removal become available and better (in terms of
logistics, economics, ecological and health side effcts) disinfectants are
developed, the removal, disinfection and dilution can be treated as sep-
arate 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 whenthere 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 Raction Products
a. Chlorine
It has recently been reported that chlorination of water and wastewater
results in the formation of halogenated organic compounds that are sus-
pected 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 chlorin-
ation 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 I.
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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 I 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 concentrations, the chlorinated purines and pyrimidines
could potentially exhibit some teratogenic and carcinogenic activities.
Bellar et al .(33) determined the nature and concentrations of organo-
chlorine compounds in the effluent of a wastewater treatment plant re-
ceiving a mixture of domestic sewage and industrial wastes. Based on the
results presented 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 dibromochloro-
methane and assumed that these compounds are formed through the inter-
action of chlorine with organic compounds in drinking water. Table III
lists the concentration found at different sampling points of a water treat-
ment plant (see Figure 1).
Rook (34) found the following compounds to be formed by chlorination
of water supplies: chloroform, bromodichlorometane, dibromochloro-
methane, 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, bromo-
dichloromethane 20.0 ug/1, dibromochloromethane 13.3 ug/1, and
bromoformlO. 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
that 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 byMcCabe and Tardiff (37). However,
these compounds are not specifically mentioned here since 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 aera-
tion 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 research
to determine the interaction of halogenated organics such as chloroform
with de.chlorinating agents of the types mentioned above. Until more is
known on this subject, it cannot be stated with any certainty that con-
ventional dechlorinating 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 is pursued on a wide scale.
d. Other Disinfectants
Bromine, bromine chloride, chlorine dioxide, iodine, permangate,
silver, ultraviolet light have iaeen used to a limited extent for disinfection
purposes. Permanganate and -silver have no known application in waste-
waters. Drawbacks for the above include: high cast, toxic side effects,
inefficiency under turbid conditions, 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 pro-
ducts.
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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. Re cent 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) which if not exceeded
would result in protection of aquatic 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 con-
cluded 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 chlor-
amines 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 chlorine and that the toxicities of the chloramines
and free chlorine 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 chlor-
ination was temporarily interrupted and no mortality was observed.
Tsai (4) studied the effects on fish of 156 wastewater treatment plants in
Maryland, northern Virginia, and southeastern Pennsylvania. All the plants
discharged chlorinated municipal wastes into small streams containing fish .
Inmost 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 prin-
cipally fish, but observed typically a clean bottom without living organisms
in the area immediately below the chlorinated outfalls. Unchlorinated dis-
charge 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 concentrations above approximately
0.02 mg/1. Ten species were not found above 0.05 mg/1.
Arthur et al. (5) studied the effect of chlorinated secondary wastewater
treatment pTanT effluent containing only domestic sewage effluent on repro-
duction of fathead minnows, Dapfania magna, and the scud Gammarus pae-
udolimnaeus. D. magna apparently was the more sensitive invertebrate
species and died at a TRC concentration of 0. 014 mg/1. Successful repro-
duction 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, including 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 (Or c on e ct e s virilis), scud (Gammarus pseudolimnaeus), snails
(Phyaa Integra and Campeloma decisum),and stoneflies (Acroneuria lyco-
rias) indicated' that the crayfishv snails, and caddisfly larvae were least
sensitive (7-day TL50 values greater than 0.55 mg/1). Seven-day TL5Q
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 12 hr of the acute tests indicating
that the lethal effect of TRC occurs rapidly.
Esvelt et al. (6, 7) and Krock and Mason (8) conducted an extensive study
on the toxicity of chlorinated municipal wastewaters entering San Francisco
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 a 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 source 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 de-
monstrated 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 Agency, 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 toxicily of this
chlorinated effluent is similar to that described above. This siudy 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 irequently shown to be
inaccurate resulting in much higher concentrations than necessary for ad-
equate 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. ] 8 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 ampero-
metric 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-
inationtechniques on the toxicity characteristic of chlorinated wastes. Under
laboratory bioassay conditions dechlorination with sodium thiosulfate at sev-
eral Michigan plants resulted in no acute mortality after 4 days in undiluted
effluent (3). Chronic and acute toxicity tests by Arthur et al. (5) usin:
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
highest concentration jji 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 dechlorinated waste. No effect was indicated at 25 percent. During
this study there also may have been adverse effects in the undiluted, un-
treated 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. Un-
realistic ally high concentrations of ozone, relative to that needed for dis-
infection, were necessary to maintain concentrations of 0.2 to 0.3 mg/1
in a testing system where acute mortality occurred. Typically, ozone dis-
sipated rapidly between the contact chamber and the test chambers. Pre-
liminary results of comparable studies at the Grandville, Michigan waste
treatment pi mt indicate that, the ozonated effluent had no signi/icant effect
on fathead m nnow reproduction, growth, or survival.
During a 6-week pilot plant study by Nebel e_t 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 acut< toxicity of
this effluent is similar to that for chlorine but the toxicity of :his effluent
declines at a. much greater rate than that for chlorine. The i ame is true
for-the chronic test. A 25 percent effluent concentration (0.018 n ij/1 bromine
residual) had no chronic effect on reproduction of the fathead min ow, where-
as a 20 percent effluent concentration of chlorinated waste (0.10 ! mg/1 chlo-
rine residual) killed all the test fish.
The principal characteristic of brominated effluent is thai 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 eit al (14) indicate that 0.25 mg/1
chlorine was lethal to Chinook salmon. AT an exposure time of 23 days,
the maximum 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. 5mg/l chlorine
and 3 mg/1 ammonia. Alderson (15) found that the-48 and 96 hr TLm for
plaice larvae was 0.032 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 percent. Eggs were not affected by ex-
posure to 0.075 and 0.04 mg/1 chlorine solution for 8 days indicating that
the protection of the egg membrane allows normal development over rela-
tively long periods even at chlorine concentrations which would be repidly
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 un-
chlorinated sewage-seawater mixture was reduced by 20 percent. Chlorin-
ated sewage further reduces fertilization success in concentrations as low
as 0. 05 mg/1 available chlorine. These results indicate that the use of chlo-
rine disinfection could contribute to reproductive failure in external ferti-
lization of marine invertebrates in the vicinity of sewage outfalls.
Galtsoff (17) observed that the pumping activity of oysters exposed to
0.01 to 0.05 mg/1 chlorine was reduced. Effective pumping could not be
maintained 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 commer-
sonii, the minnows, Notropis cornutus, N. analostanus and N. prooni, and
the catadromous eel, AnguillaTbstrata, in certain areas ofTKe 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 temperature
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. Barnacle
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
chlorination 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 cauaed respective mortality rates of 80
and 90 percent, 3 hours after exposure. Grass shrimp, Palaemontes pugio,
and the amphipod, Melita nitiday showed a delayed death response after ex-
posure 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 et al. (22) investigated the effects of chlorination on phyto-
plankton producHvTEy. 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 phy-
toplankton 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 et al. (24, 25) National Marine Water Quality Laboratory, West
Kingston,. REoHe Island, observed a 55 percent decrease in the ATP content
of marine phytoplankton exposed to 0. 32 mg/1 chlorine residual for two min-
utes and 77 percent decrease after 4.5 mimttes of exposure to chlorine con-
centrations below 0. 01 mg/1. A 50 percent depression, in the growth rates
of 10 species of marine phytoplankton exposed to chlorine concentrations rang-
ing from 0. 075 to 0. 25 mg/1 for 24 hours was also measured.
18
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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 mar-
ine 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 re-
sulting 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 populations. Basch and Truchan (26) recommended maximum con-
centrations of 0.02 and 0.005 mg/1 for warmwater and coldwater fish, re-
spectively. EIFAC (27) has suggested criteria dependent upon pH and temp-
erature with an acceptable upper limit of 0. 004 mg HOC1/1 (TRC from 0. 004
mg/1 at a 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 sen-
sitive 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., sodiuni
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 recommended 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 sadism! 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 tofreshwater 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. Sublethai concentrations of chlorine can reduce productivity of marine
phyt oplank ton.
9. Larval stages of marine forms appear to be more sensitive to chlorine
than cither 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 project;; have
provided the basis for the present research program and nave greatly
contributed to the present state of the art. A list of completed and on-going
projects 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 alter-
native methods for disinfection of wastewater; and test the toxicity of
those methods to aquatic life. The alternative processes being studied are
disinfection with ozone and bromine chloride, and the neutralization of re-
sidual 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 equipment 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 ap-
plication.
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 waste-
water 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 exMrtains ammonia and most of the chfo^eine applied is very rapidly con-
verted5 to monochloramine at normal wastewateir'pH of slightly above 7. 0. Other
chlorinated compounds such as organic chlgramines are formed but these are
of little germicidal importance in the disinfecticSn of wastewater.
Status
Chlorine is currently the predominant wa'atewater disinfectant and it is
essentially the exclusive disinfectant if one^uicludes its counterpart, sodium
hypochlorite, which will be covered subsequently1' in a separate section. A mini-
mum chlorine contact time with a specifiecU?phlorine residual is included in
some state standards. Others rest on. EPA^regulations or specify that certain
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 exteemely competitive. There was some^concern for availability of ade-
quate siajpplies of both chlorine and snipping*c.pntainers early in 1974 (1). In
ttoe EPA Disinfection Policy Ta-sk Force meej±r?gfon July 9, 1974, it was reported
that tkere was no shortage of either container^s^or chlorine for water and waste-
waiter disinfection.
Safety
Liquid chlorine is a hazardous chemical and chlorine gas is toxic and can
cause d^eath by suffocation (2). It irritates the^respiratory tract mucous surfaces
and the skin. Direct contact with liquid^Jchlorine can cause serious burns.
safety equipment (gas masks) is required forss|rp.ergency protection in all poten-
tially dangerous areas. Safety precautions iriu^ibe excercised in all shipment,
storage, and use areas. The liquid vapq^zjrs at atmospheric pressure and
ambient temperatures. The gas is 2-1/2 times^as heavy as air and will persist
in low areas.
Reliability
CMowine is generally a reliable diissara^ctant. There is clear-cut evi -
cLertee tfet chlorination of waystewater dtestrojjPBii enteric pathogenic bacteria.
In a study on the occurrence of Salmonellae in;the receiving stream after waste-
water chlorination, Salmonellae were not detected-in either chlorinated effluents
or the receiving stream during a 7-month period when effluents were chlorina-
ted. After chlorination was discontinued, Salm'bttellae were isolated. When chlo-
rination was resumed, however, they were^rnpt detected in samples collected
dmring a 4-week period (3).
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The value of the coliform test is indicated by the fact that "... epidemics
of hepatitis originating in chlorinated water supplies judged satisfactory by the
coliform test have not been reported except where obvious deficiencies in chlori-
nation practice were shown or suspected1 (4). Apparently, the coliform test pro-
vides a good measure of protection against the one virus disease that has fre-
quently been the cause of waterborne epidemics. Basically, its effective use
for disinfection of wastewater requires an understanding of the disinfecting effi-
ciency 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 monochloramine
and what is available indicates that it is a slow acting virucide (5). To ensure
adequate protection from viruses, long-term exposure to monochloramine is
required, whereas chlorination to breakpoint (HOC1 residual) will rapidly de-
stroy 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,
"Reduction 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 Interagency Agreement EPA-IAG-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 is 8 mg/1 to achieve disin-
fection. 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, jzr/KGal 3.49 1.42 0.70
Sodium Hypochlorite (NaOCl)
General
The disinfecting potency of 1. 0 mg/.l of chlorine derived from sodium hypo-
chlorite is just as effective as an equivalent amount of chlorine as hypochlorite
ion (OCirderived from liquified chlorine gas. Either chlorine gas or sodium
hypochlorite in aqueous solution at concentration's 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 hypo-
cfalorite solutions must be protected 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 85°F 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 prox-
imity to heavily populated areas.
Equipment and Chemical Supplies
With the exception of the feeder, storage, and some piping, a hypochlorina-
tion syste.m 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
problems are anticipated.
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Availability of sodium hypochlorite should be'essentially the same as for chlo-
rine. 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. Nevertheless, 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 «f differ-
ence in capital cost of liquid chlorine and sodium hypochlorite systems (9).
Current costs of sodium hypochlorite indicate that available chlorine 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 L
Dechlorination with Sulfur Dioxide (SO?)
General
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/galat 60°F).
Upon dissolving sulfur dioxide in water a weak solution cf sulfurous acid is
25
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formed. The dechlorination reaction of sulfur dioxide with both free and com-
bined 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 chloride ion. The sulfur 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 effep-t on chlorinated organic compounds resulting
from disinfection with chlorine. However research is required to determine
if this assumption is correct.
Status
Sulfur dioxide has long been used to neutralize chlorine in treatment of
idrinking water, but its use for .dechlorination of wastewater is just getting
underway. Information obtained in October 1974 on four wa.stewater treatment
plants with average daily flows -ranging from 4.0 mgd to 160 mgd indicaied
no serious problems in dechlorinating with sulfur -dioxide. Of these plants,
the Sacramento City plant (flow 50 mgd) had been using sulfur dioxide dechlori-
nation for 9 months (12).
Equipment and Chemical Supplies
-Equipment for feeding sulfur dioxide is very similar to thai used for chlorine
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 70 F 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
result, some states are requiring reaeration to increase the dissolved oxygen
content of the effluent when sulfur dioxide is used to dechlorinate.
26
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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 disin-
fectants such as ozone and ultraviolet light which leave no lasting residual.
Costs
Costs for both dechlorination with sulfur dioxide and restoration of dissolved
oxygen ccntent are presented in Tables II and III. To obtain the total cost of
disinfection, the chlorination cost in Table I must be added to the dechlorination
and the o :ygen restoration cost in Tables II and III (7).
Table II
Dechlorination with Sulfur Dioxide Cost
Plant Size, MOD 1 10 100
Capital Cost, $ 11,000 29,000 94,000
Disinfection Cost, /«/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/KGal 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
cm the carbon. This polishing step not only alleviates the problem of toxicity
associated with chlorine but it also removes residual refractory organics
and 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
facilities. This technology is applicable for the design and operation of car-
bon 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 treatment 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
tertiary 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 asso-
ciated 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. How-
ever 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 CO2 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 com-
bined chlorine. Long term tests are still required to determine the influence
of organic loadings on the efficiency of the chlorine removals and to deter-
mine if aftergrowth 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 assume that the carbon will perform for several years before
replacement, thereby eliminating carbon regeneration facilities. This as-
sumption needs verification before such a system can be placed into opera-
tion. Since the costs for dechlorination with carbon are significantly higher
than other alternative processes, carbon dechlorination research is classi-
fied 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, c/K Gal 19.00 8.60 3.28
Ozone
General
Because of its high oxidation potential, ozone has received the most
attention as a disinfectant alternative to chlorine. Ozone is a chemical
disinfectant that may derive its germicidal properties from the formation 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 gen-
eration is between 1 and 3 weight %. Ozone decomposes in water to formh
molecular oxygen.
29
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.Status
Ozone hasbeenused 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 tor ozunation.
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 manu-
facturers 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
«ir. 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 pre-
vent 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 allowable concentration for an eight hour day exposure of ozone
to huma.is 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 required. 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 waslew'c'.ter has assigned ozone a high priority. Work is underway to
optimize ozone utilization by improving various contacting systems. Re-
30
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search plans also call for demonstrating ozone at two of the five previous-
ly 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
dosage. Present technology utilizes a constant ozone dosage which results
in excessive ozone consumption or inadequate disinfection.
Residual oxidation products need to be investigated to determine if toxic
compounds are formed when the reaction of ozone with organics does not pro-
ceed to completion (CC>2and HJD).
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
-------
effect is a function of wave length and is greatest between 2500 and 2600
aagstroms (A). With the advent of low-pressure mercury lamps approxi-
mately 85% of fie lamp's energy is emitted at 2537 A (19).
For UV to l>e an effective germicide, the energy dosage must reach the
organism. Some of the factors that may affect the penetration of UV energy
into water are urbidity, 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 hotels, cruise ships
restaurants and vacation camps. There are many industrial and product
w-ater applications that use UV, such as breweries, pharmaceutical man-
ufacturers, and fish hatcheries (20).
UV has net been studied extensively as a disinfectant for wastewater;
however, its feasibility was demonstrated at 44, 9-&0 GPD at St. Michaels,
MD (21). Its reliability was highly dependant upon effluent quality. Addi-
tional research is required to establish minimum pretreatment require-
ments to optimize design parameters, such as UV dosage, hydraulics,
contact t me ard energy requirements.
There is under construction a 2 MGD treatment plant with UV disinfec-
tion 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
competitive market if UV surfaces as a viable alternative. The equipment
manufacturers have made significant product improvements in regard to
equipment, maintenance, contact, and dosage. The manufacturers incor-
porate 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 precau-
tions covered under ozone may also be required for UV systems. The
newer designs of UV equipment have enclosed chambers to protect opera-
tors .against irradiation 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. Poor quality effluent will require
tertiary treatment to provide adequate disinfection. Additional research is
needed to provide process and cost optimization to ensure adequate disinfec-
tion 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 costs 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, $/KGal 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 chlora-
mines in bactericidal and viricidal 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 Chem-
ical Co. when their marketing studies indicated that bromine would be a-
vailable for other uses as the quantity of leaded gasoline decreases. Pre-
sently 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 supplies 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
chloride is an effective disinfectant requiring no pretreatment i'or an acti-
vated sludge effluent. Bromine chloride can accomplish the same degree
of disinfection as chlorine with a lower final halogen residual, but the min-
imum 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. Thetoxicity
of brom'inated organic compounds is generally greater than the correspond-
ing chlorine compounds and additional studies will be required to determine
the health effect consequences. Since its chemical behavior is similar to
chlorine, its development has progressed more rapidly than other alterna-
tives. To take advantage of the potential for lower halogen residuals, in-
struments need to be developed to ensure adequate monitoring of the efflu-
ent. Because of the potential commercial applicability of bromine chloride,
the manufacturers have made a major contribution to its accelerated de-
velopment.
Costs
The cost of disinfecting wastewater with bromine-chloride is shown in
Table VII. A cost summary is shown in Table VIII listing the disinfectants
with their capital and total disinfection costs.
Table VII
Bromine Chloride Disinfection Cost (7)
Plant Size, MGD 1 10 100
Capital Cost, $ 47, 000 129, 000 414, 000
Disinfection Cost, «4/K Gal 4.52 3.04 2.65
OTHER POTENTIAL DISINFECTANTS
Chlorine Dioxide
Chlorine dioxide (C1O2 ) is one of the newer halogen disinfectants that
have shown promise for use in water and wastewater treatment. It is a
powerful oxidizing agent and an excellent disinfectant.
Chlorine dioxide is unstable and extremely corrosive. In practice, it
is usually generated from the reaction between sodium chlorite solution
and chlorine in contact with the water to assure that the gas remains in
solution to avoid explosion hazard. Sodium chlorite (NaClC^), 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 wastewaier.
Factors other than the cost of the chemicals used may govern the expense
of wastewater treatment. Here, -however, only cost of materials is consid-
ered. The cost of NaC103and CL^required to produce one pound of CIO is
about 13 times more than oae pound" of CL.
Lime at pH 11.0 or Higher
It is unlikely that lime would 3®e seriously considered for disinfection
only. However, lime has pronoimeed potential for icornbined treatment and
disinfection of wastewater.
Results from EPA sponsored studies under Grant No. 16100 PAK,
"Lime Disinfection of Bacteria at Low Temperature," are indicative of the
effectiveness of lime as a disinfectant. Even in the presence of relatively
high concentrations of organic matter and uncter the adverse conditions of
low temperature sewage can be disinfected to a safe level by lime treat-
ment to 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 peri-
od (30 minutes or less), even at 1° C. Additional benefits that can be
realized from lime treatment are reductions in organic materials and phos-
phorus. If the removal of organic chemicals and phosphorus is not neces-
sary, the cost of disposing of the sludge resulting from lime treatment would
have to be considered as part of the disinfection cost.
Bromine
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 residualcorreentrations. As with chlorine, the amine form
is produced when Ammonia is present, and the ^breakpoint phenomenon has
been demonstrated. Bromine, hypobromous.acid (HOBr), and monobroma-
mine are considered nearly equal in bactericidal properties and essentially
equal to free chlorine %t comparable pH. Some of the advantages given
for using bromine are: (a) it is easier to feed and not as hazardous to
store as chlorine; and (b) the bactericidal efficiency of bromamines is much
greater than thai 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 pll, 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 combining 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 unsuit-
able 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 25° 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 unit of germicidal
effectiveness. Its 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 reduction in dosage
with iodine might be considered because of probable increased presistence
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 produced 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, elec-
tron accelerators, reactor loops, fuel elements, and mbced fission pro-
ducts. Each must be analyzed in terms of cost, availability, characteris-
tics, and installation requirements. All radiation devices require special
shielding and handling facilities, constant monitoring of radiation areas,
keeping of personnel exposure records, etc. The electron accelerator fa-
cility 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 suspensions of Escherichia coli indicates at most an additive ef-
fect. 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 wastewater treatment.
37
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Low ptH as a Disinfectant
Exposure of microorganisms to extremes in hydrogen ion concentration
is a relatively ineffective method of disinfection. It is known that Escheri-
chia 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
entering the small intestine. Thus, for low pH to be a truly effective
disinfectant, extreme acidity .mast persist for a considerable period of
time.
38
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TABLE VIII
COST SUMMARY
PLAN'!' SlX/Ji, IV1C.D
CAPJTAJ, COST
PROCESS
Chlorine
Chln<-/ A ir
(l-.'.i.n,:-/() <, /•;< .-i
1
$K
GO
70
120
640
1'JO
160
70
f>0
1, 450
. . Q ! j
•'•' Teri.iui\y ( r'.-^
55.90 20.20 14.00
ir, not incliulod in lh<::::<.' costs.
-------
C hi "ri.no
TABLE IX
SUMMARY ON TIIK STATUS OF DISINFECTANTS
Stnle-of KiKM-gy Health
iho-Art KW.li/MG KJTc.cLs
Operational HO
Sodium "nynix.-hlori.itt Operrational XCO
'iiK'/Sull"'.!)- "Dioxido C Operational 90
1'Miloi. Plant. HO
( Mij
C)i'{(anics
Or gun- OK:
Toxrc
Efl'ccl:
Lo\v
Lo\v
Pilot Plant. 8u() Tini-;riown
Lov/
Pilot Plant 409 Uul;no\vn
Lo\v
Plan! 3-iO. A
Filc-H Plant. 90
40
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APPENDIX A - RESEARCH AND DEVELOPMENT PROJECTS
Listed below are brief descriptions of EPA research projects on
disinfection.
I. On Going Projects
A. "Parallel Ozonation and Chlorination with DechlorLnation of
Chlorinated Effluent." Project No. 802292, City of Wyoming.
A study on disinfection effectiveness 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 waste-
water.
C. "Reduction of Toxicity Emission Rates from Wastewater Treat-
ment 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 and
Effluent Disinfection", Project No. 803294, Utah State Univer-
sity
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 Com-
pounds". Project No. 800370, University of Cincinnati.
Determine the capability of chlorine and chlorinated com-
pounds to destroy viruses in wastewaters.
F. "NewMicrobial 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.
G. "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-660/2-73-017.
D. "Hypochlorite Generator for Treatment of Combined Sewer
Overflows", Report No. 11023 DAA 03/72, Ionics Incorpor-
ated.
E. "Ultraviolet Disinfection of Activated Sludge Effluent Discharg-
ing to Shellfish Waters", Project No. WPRD 139-01-68, The
Town of St. Michaels.
F. "Disinfection of Sewage Effluents'', Project No. 17060 DNU
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.
L Bench-Scale High-Rate Disinfection of Combined Sewer Over-
flows with Chlorine and Chlorine Dioxide'1, Project No. 802400,
O1 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 one.
- Seasonally or hydrqgraphically 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 exceptions: 1 State.
- Case-by-case disinfection requirements: 19 States.
- No specific requirements: 1 State.
- Secondary treatment - no specific disinfection requirment: 19 States.
- No standards: 8 States.
- Munimum chlorine residual: 5 States.
43
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APPENDIX C
TABLE I. Tentative Identifications and Concentrations of Chlorine-
Containing Constituents in Chlorinated Effluents
concentration of
Orcianic Compound
Identification a (up/liter)
5-Chlorouracil 4.3
5-Chlorouridine 1.7
8-Chlorocaffeine 1.7
6-Chloroguanine 0.9
8-Chloroxanthine 1.5
2-Chlorobenzoic acid 0.26
5-Chlorosalicylic acid 0.24
4-Chloromandelic acid 1.1
2-Chlorophenol 1.7
4-Chlorophenylacetic acid 0.38
4-Chlorobfinzoic 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 Hater from Sewaae Treatment Plant
Concentration Cwg/1)
Influent Effluent Effluent
before before after
Compound Treatment Chlorination Chlorination
Methylene chloride
Chloroform
1 ,1 ,1-Trichloroe thane
1 ,1 ,2-Trichloroethylene
1 ,1 ,2,2-Tetrachloroethylene
£ Dichlorobenzenes
£ Trichlorobenzenes
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
3A11 confirmed by GC-MS
45
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TABLE III. Trihalogenated Methane Content of Water from Water Treatment
Plant
Sample Source Sampl'rng
Point
Kaw river water ;i
River water treated with 2
thlorine and alum-
chlorine contact time
A' 80 min.
3-day-old settled water 3
Water flowing from 4
settled areas to filters'3
Filter effluent 5
'Finished water 6
Free
Chlorine
ppm
u.u
6
2
2.2
Unknown
1.75
Concentration
Bromo
Ghloro- dichloro-
fonp methane
O.y
22.1
60.8
127
83.9
94.0
a
6.3
18.0
21.9
18.0
20.8
lug/i)
Dibromo-
chloro-
methane
a
0.7
1.1
2.4
1.7
2.0
JNone detected. If present, the concentration is 0.1 uq/1.
^Carbon slurry added at this point.
46
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TABLE IV
SOME RECOGNIZED AND SUSPECT CARCINOGENS FOUND
IN MUNICIPAL WATER SUPPLIES
CHEMICAL
Bis (2-Chloroethyl) Ether
Chlorodibromome thane
Bromoform
Benzene
Carbon Tetrachloridc R
Bis Chloromethyl Ether R
Chloromethyl Methyl EtherR
Chloromethyl Ethyl 1,'ther
ASSOCIATED WATERWAY
Ohio River
Ohio River
Ohio River
Ohio River and Wabash River
Ohio River
Ohio River
Ohio River
Ohio River
R
*
recognized carcinogen
decomposes readily
47
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TABLE V. Halo-organic Compounds Identified 1n 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
TO. bromophenyl phenyl ether
11. carbon tetrachloride
12. chlordan(e)
T3. chlorobenzene
74. chlorodibromomethane
15. 1,2-bis-chloroethoxy ethane
16. chloroethoxy ether
17. bis-2-chloroethyl ether
T8. b-chloroethyl methyl ether
19. chloroform
20. chlorohydroxy benzophenone
21. bis-chloroisopropyl ether
22. chlororcethyl ether
23. chloromethyl ethyl ether
24. m-chloronitrobenzene
25. 3-chloropyridine
26. DDE
.27. DDT
28. dibromobenzene
29. dibromochloromethane
30. dibromod.ichloroethane
31. 1,4-dichlorobenzene
32. dichlorodifluoroethane
33. 1,2-dichloroethane
34. dichloroe.thyl ether
35. dichloromethane
36. dieldrin
37. heptachlor
38. heptachlor epoxide^
39. 1,2,3,4,5,7,7-heptachloronorbornene
40. hexachlorobenzene
41. hexachloro-1,3-butadiene
42. hexachlorocyclohexane
43. hexachloroet'hane
48
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TABLE V (cont.)
44. methyl chloride
45. octyl chloride
46. pentachlorobiphenyl
47. pentachlorophencl
48. 1,1,3,3-tetrachloroacetone
49. tetrachlorobiphcnyl
50. tetrachloroethare
51. tetrachloroethylene
52. trichlorobenzene
53. trichlorobiphenyl
54. 1 ,T ,2-trichlorocthane
55. 1,1,2-trichloroethylene
56. trichlorofluorofrethane
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 U
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 Thistlewayfe, D. K. B., " Sewage Pollution and Sea
Bathing", Second International Conference on Water Pollution Research,
1964.
3. Morbidity and Motality Weekly Reports. "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 and 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., 19£8, 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 Sym-
posium 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, O. and McGowan, F., Northeastern U.S. Water Supply Study
Potomoc 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 Poll. 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 Quanti-
tative Method for Salmonella Detection in Polluted Waters ', Applied
Microbiol. 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, Clarence 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 Coxsachie 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. Vol2.,
McMillan, New York.
23. Shuval, H.I. et al. 1966, "The Inactivation of Enteric Viruses in
Sewage by ChTormation in: Adv. Water Pollution Res., Vol. 4,
McMillan, New York.
24; Craun, F.G. and McCabe, J. L. "Review of the Causes of Water-
borne-Disease Outbreaks", JAWWA 65, 74(1973)
52
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25. Craun, K.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, Aug.
1974, Paper No. 41.
29. Pearson, E. A., "Conceptual Design of Marine Waste Disposal System",
Int. Symp. on Discharge of Sewage from Sea Outfalls, London, Aug.
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. II. 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
Freshwater", 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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3B.. Snoeyink, V.L., etal. A-ctive Carbon: Dechlorination and the Adsorption
of Organic Compounds11, Chemistry of Water Supply Treatment send
Distribution, A. J. Rubin, Ed., Ann Arbor Science, 1974.
39. Pair, 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. Mcrkens, J. C., "Studies on the Toxicity of Chlorine and Chloramines
to the Rainbow Trout. "Water & 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. &
Ind. Wastes, 22, 1432 (1950).
3. "Chlorinated Municipal Waste Toxicities to Rainbow Trout and Fathead
Minnows. " Mich. Dept. of Natural Resources, Water Poll. 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 al., "Comparative Toxicity of Sewage-Effluent Dis-
infection to FresKwaFer Aquatic Life. " Water Poll. Control Res. Ser.
EPA, Washington, D.C. (1975).
6. Esvelt, L. A., et al., "Toxicity Removal from Municipal Wastewaters. "
Vol. IV, "A Stud~y~of Toxicity and Bio stimulation in San Francisco Bay-
Delta Waters. " SERL Rept. No. 71-7, San Eng. Res. Lab., Univ.
of California, Berkeley (1971).
7. Esvelt, L. A. , et al., "Toxicity Assessment of Treated Municipal Waste-
water. " Jour. Wafer 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 Serviai, J. A., "Acute Toxicity of Municipal Sew-
age to Fingerling Sockeye Salmon. " International Pacific Salmon Fish-
eries Commission Progress Report No. 29, New Westminster, B.C.
18 p (1974).
10. Servizi, J. A. and Martens, D. W., "Preliminary Survey of Toxicity
of Chlorinated Sewage to Sockeye and Pink Salmon. " International Paci-
fic Salmon Fisheries Commission Progress Report No. 30, New West-
minster, B.C. 42 p (1974).
11. Enoeyink, V. L. , and Markus, F. I. , "Chlorine Residuals in Treated
Effluents." Watep & Sew. Works, 121, 35(1974).
12. McKersie, J., "A Study of Residual Chlorine below Selected Sewage
Treatment 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. , et al., "Ozone Disinfection of Industrial-Municipal Secon-
dary Effluents. """Jour. Water Poll. Control Fed. 45, (1973).
13. Holland, G. A. et al. , "Toxic Effects of Organic Pollutants on young
Salmon and TrouTT "~~ 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 3Rlaice, Pleutonect.es platessa L. " In:. Marine Pol-
lution and Sea Life. "Fishing News, Ltd., LondorTp 312-315 (1972).
.tJB. Muchmore, D. amd B. Epel. , "The Effects of Chlorination of Waste-
water on Fertilization in .Some Marine Invertebrates. " Mar. Biol.
19:93-95 (1973).
•17. Galtsoff, P. S. , "Reactions of Oyste-rs lo Chlorination. " 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).
IB. Tsai, C., "Changuss in Fish Populations and Migration in Relation to_
Increased Sewage Pollution in Little Ratux-ent River, Maryland. " Ches-
apeake Sci. 11:34-41 (1970).
20. Waugh, G.D., "Observations on the -Effects of Chlorine on the Larva**
of Oysters, Ostr.ea edulis L. , and Barnacles Elminius modestus, Dar-
win. " Ann. Appl. .Biol. 54r??3-440 (1964).
21. McLean, R. I., "Chlorine and Temperature Stress in Estuarine Inver
tebrates. " Jour. WPCF. 45:837-841 (1-973).
22. Carpenter, E. J.,, B.B. Peck and S. J. Anderson., "Cooling Wate
Chlorination and IRroductivity of Entrained Phytoplankton. " Mar. Bio]
16:37-40 (1072).
"23. Hiray.ama, K. and iR. ZHmana. ., "inHuences of High Temperature aj
Residual Chlorine on Marine Phytopfcankton.. " Mar. Biol. 7:205-21.3
(1970).
24. Gentile, J. H., J. Cardin, M. Johnson and S. Sosnowski. , "The
of Chlorine on thfe 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. Ell*AC, "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 Residual Chlorine on Aquatic 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 Scries No. 154 Reinhold Pub.
Corp., New York (1962).
3. Brezenski, F. T-, et al. "The Occurrence of Salmonella and Shingella
in Post-ChlorinatecTand Non-Chlorinated Sewage Effluents and Receiv-
ing Waters." Health Lab. Sou, 2, 40 (1965).
4. Chambers, C.W., "Chlorination 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 Monochlorimine" Tin Press, Proc. 7th Intnl. Conf. Water Poll. Res.
Presented in Sept. 1974, Paris] France.
6. Scarpino, P.V., et al. WA Comparative Study of the Inactivation of
Viruses in Water~"T>y~~ChIorine" Water Res. (G. B.) 6, 959 (1972).
7. Smith, R., ej, al. "Cost of Alternative Processes for Wastewater
Disinfection" 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 Chlorination of Wastewater, Water Poll. Control Fed.
In press. "
9. Baker, R.J.,. " Characteristics of Chlorine Compounds" Jour. Water
Poll. Control Fed., jU 482 (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 (Oc-l. 1974).
58
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13. " Process Design Manual for Carbon Adsorption." Environmental
Protection Agency, Technology Transfer, October, 1973.
14. Collins, H. F. et al. "interim Manual for Wastewater Chlorination
and DechlorinationTractices",' 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. e_t al. "Ozonation as an Alternative to Chlorination for the
Disinfection~bTTreated Wastewaters, Metropolitan Sewer Board of
the Twin Cities, October, 1973.
17. Mittler, S. et al. "Toxic ity of Ozone", Ozone Chemistry and Tech-
nology 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. et al. "Study of Uliraviolet Disinfection of Water and Fac-
tors in Treatment Efficiency ^',.,Pjit>Uc Health Reports, August 1965,
volume 80, number 8, pp 695-705, " '
20. " Facts You Should Know About XHtfadynamics", Brochure by Ultra-
dynamics Corporation, Pattersdn,' N. J.
21. " Ultraviolet Disinfection of Activated Sludge Effluent Discharging to
Shellfish Waters", Draft Report, Project WPRD 134-01-68.
22. Filbey, A.H., "Bromine Chloride as an Alternate Disinfectant",
Chlorine Residual Policy Seminar, State .of Maryland> November,
1974.
23. Jackson, S. C. "Chlqrobromination of Secondary Sewage Effluent"
Dow Chemical Company, December, 1974.
24. Walkenhuth, E.G. e_t al. "An Investigation of Bromine Chloride as a
Biocide in Condenser Cooling : Water, 35th Annual Meeting Inter-
national Water Conference, Pittsburgh, Pennsylvania, October, 1974.
59
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