DISINFECTION
OF
WASTE WATER
1970 STATUS
DOI/FWQA-0002
ROBERT A. TAFT WATER RESEARCH CENTER
ADVANCED WASTE TREATMENT RESEARCH LABORATORY
FEDERAL WATER QUALITY ADMINISTRATION
U.S. DEPARTMENT OF THE INTERIOR
CINCINNATI OHIO
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Introduction
In this first annual report covering the status of disinfection of wastewater
and AWT treatment plant effluents, it is "believed that a look at where we
stand new and what is planned for the future should provide a "better under-
standing of what may "be expected from this subprogram.
Present Status of Chlorination
The most desirable objective is to be able to say that application of a
specified dose of chlorine would provide safe disinfection of all effluents.
The coliform test should be considered the primary standard; the chlorine
residual can only be considered as a secondary standard and it is only valid
to the extent confirmed by the results obtained in the coliform test. The
conclusions of Browning and McLaren (jour. Water Poll. Control Fed., August
1967) indicate the problems of operating on a basis of a specified combination
of chlorine residual and contact time. They state "Generally speaking, a
correlation exists between chlorine residual and coliform density (coliform
densities decrease with increased chlorine residuals) but the individualities
of waste treatment plants and their effluents make it difficult to apply a
correlation determined from one plant to other plants." Each plant must
develop its own data for correlating chlorine dosage, residual, and contact
time to yield predictably the desired reduction in coliform count.
The most highly clarified and oxidized effluents are the easiest to disinfect.
If good control of microorganism content is to be attained by Chlorination,
good secondary waste treatment should be the minimum. Chlorination of pri-
mary effluents should not be considered an acceptable practice in most sit-
uations except as an interim process until secondary treatment facilities
can be constructed.
Some concern has been expressed regarding the fact that numerous viruses
are more resistant to chlorine than the coliform bacteria. Methods of using
viruses as an indicator of Chlorination efficiency have not reached the stage
where practical tests for routine use are available. The coliform test still
remains an effective criterion for disinfection of drinking water. Except
for hepatitis, clearly defined outbreaks of virus diseases traceable to
drinking water have not been reported (Clarke, Berg, et al., Adv. Water Pol.
Control Research, Pergammon Press, McMillan Company, New York, Vol. 1, 1964).
Epidemics of hepatitis originating in chlorinated water supplies judged satis-
factory by the coliform test have not been reported except in instances where
obvious deficiencies in Chlorination were shown or suspected. It is not,
therefore, considered likely that effluents disinfected to satisfactory coliform
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destruction levels are much of a health hazard. JWQA. has funded a grant
(69-G385) to investigate the possibility of locating a new "bacterial indi-
cator that is sufficiently more resistant than coliform organisms to pro-
vide a safety factor for virus destruction. The emphasis is on the dis-
covery of an organism that can be enumerated by simple plate count or MP
procedures.
Status of Besearch
Because of personnel limitations and other problems, research in the dis-
infection program has been limited in scope thus far. The outlook for the
future is improving and a marked increase in the number and variety of
grant and contract projects is anticipated in FY 19T1.
In-House;
There have been numerous reports in the literature of a major synergistic
effect of gamma radiation on the disinfecting action of chlorine, but the
work reported has not been adequately controlled. An investigation to de-
termine whether gamma radiation exerts a synergistic effect on the dis-
infecting action of chlorine is now in progress. This work is being done
under very carefully controlled conditions. Present progress indicates
that this project will be completed in SY 19T1> and it is anticipated that
definitive data will be produced to either support or negate the existence
of a synergistic effect.
Grants;
Grantee Subject project Director
Expected Comp. Date
Illinois State Water Disinfection of _ „ ,,
Survey, University of Sewage Effluents v *' w* b°-LXO
Illinois, Urbana, with Chlorine and 9/3Q/TO
Illinois. Bromine.
City of St. Michaels Controlled Treatment John A. Roeber
St. Michaels, Maryland. System-Ultraviolet 7/0/70
(Clow Waste Treatment Disinfection; ''y/ '
Division Aer-o-Flo
Yeomans, Melrose
Park, Illinois En-
gineering Operator for
Grantee)
University of Illinois New Microbial Indi- Dr. R. S. Engelbrecht
Urbana, Illinois cators of Wastewater 9/30/71
"* Disinfection.
Much of our research in disinfection of wastewater deals with problems re-
lated to the use of chlorine. Chlorine, however, is not necessarily the
answer to all of our disinfection problems, and little information is avail-
able regarding the use of other disinfectants for the destruction of micro-
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organisms in wastewater. .Other disinfectants are, therefore, "being in-
vestigated. The program is planned to develop, as rapidly as possible,
methods for the use of a variety of disinfectants and provide guidelines
'for their practical application. The rationale for this approach is to
make avs-ilable to the sanitary engineer a spectrum of proven disinfection
processes from which he can select the one most applicable to a specific
•waste treatment disinfection problem.
Research Statements of Heed
The extent to which the Disinfection Subprogram can satisfy the needs of
the respective Regional Programs depends upon how veil we can identify
those needs and formulate work programs to satisfy them. Satisfaction
of those needs can best be expedited by good liasonwith the Region. It
would be most helpful if the Regions would submit statements of research
needs to cover specific problems in need of solution. The development
of an adequate research work plan to satisfy a particular need, however,
depends upon the content of the need submitted. This can best be accom-
plished through a preliminary discussion of the proposed need by the
Program Chief and the proponent.
The Commercial Telephone Number: (513)-8Tl-l820, ext. 202
The JTS Telephone Number: (513)-871-l820, 6-202-
C. W. Chambers
Program Chief, PPB 1706
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