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 ------- 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 ------- - 2 - 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- ------- - 3 - 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 ------- |