small staff carried out a study of the germicidal properties of the 

 quaternary ammonium compounds and their use and value for sanitizing milk 

 and food utensils. 



During the First World War methods were developed for the disinfection 

 of water at army posts and for military operations in the field. An inten- 

 sive and comprehensive study was made to evaluate the bactericidal 

 efficiency of free chlorine and chloramines at different residual levels. 

 The results of these studies were made available immediately to the army 

 and navy, and the results guided the military in obtaining the most 

 effective and economical use of chlorine for water disinfection. These 

 studies established a scientific basis for municipal water-chlorination 

 practice. 



The trend of water-supply research from the 1920's into the early 

 1940's is indicated by the title of papers from the Cincinnati laboratory. 

 Representative of these are the following: "The Bacteriological Examina- 

 tion of Water"; "The Selection of a Dilution Water for Bacteriological 

 Examinations"; "Suggested Procedures for the Presumptive Test in the Deter- 

 mination of the Coli-aerogenes Group"; "Comparison of the Enumeration of 

 Bacteria by Means of Solid and Liquid Media"; "Determining the Bacteriologi- 

 cal Quality of Drinking Water"; "Notes on the Relation Between Coliforms 

 and Enteric Pathogens"; "Influence of pH and Temperature on Survival of 

 Coliforms and Enteric Pathogens When Exposed to Free Chlorine"; "Relative 

 Resistance of Escherichia coli and Eberthel la typhi to Chlorine and 

 Chloramine"; Influence of pH and Temperature on Survival of Coliforms and 

 Enteric Pathogens When Exposed to Chloramine"; "Bactericidal Properties of 

 Free and Combined Available Chlorine"; Bactericidal Properties of 

 Chloramines and Free Chlorine in Water"; and "Bactericidal Efficiency of 

 Quaternary Ammonium Compounds." 



During the 1920's and 1930's the fecal coliform tests were used in 

 conjunction with the BOD (Biochemical oxygen demand) in all pollution sur- 

 veys. Methods for conducting these tests have been included in "Standard 

 Methods for the Examination of Water and Wastewater" by the American Public 

 Health Association, et al_. for many years. 



At the end of the Second World War, membrane filter techniques were 

 developed, compared with earlier procedures, and standardized. In this 

 period studies were made to develop methods for distinguishing human coli- 

 forms from those of other animals. In the early fifties viruses in water 

 supplies were studied at the Robert A. Taft Sanitary Engineering Center in 

 Cincinnati. These studies were directed toward the detection, enumeration, 

 and production of viruses in the laboratory, the determination of their 

 effects, and their control or removal by sewage treatment. A large number 

 of papers appeared in the 1960's describing the results of this research on 

 viruses in water supplies. 



Studies of the toxicity of heavy metals in domestic water supplies have 

 been in progress for a number of years in several laboratories. This 

 activity was expanded because of the increase in metals and the need for 

 more definite data for the setting of drinking water standards. The explo- 



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