||Inactivation of Particle-Associated Coliforms by Chlorine and Monochloramine.
Berman, D. ;
Rice, E. W. ;
Hoff, J. C. ;
||Environmental Protection Agency, Cincinnati, OH. Water Engineering Research Lab.
Microorganism control(Sewage) ;
Water pollution control ;
Coliform bacteria ;
Chlorine inorganic compounds ;
Particle size ;
Sewage treatment effluent
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Sieves and nylon screens were used to separate primary sewage effluent solids into particle fractions of <7- or >7 micrometer size. Coliforms associated with the <7 micrometer fraction were inactivated more rapidly by 0.5mg of chlorine per liter at 5 deg C and pH 7 than coliforms associated with the >7 micrometer fraction. Homogenization of the >7 micrometer fraction not only resulted in an increase in the number of <7 micrometer particles, but also increased the rate of inactivation to a rate similar to that of the <7 micrometer fraction. With 1 mg of monochloramine per liter at 5 deg C and pH 7, particle size had no appreciable effect on the rate of inactivation. The results indicate that coliforms associated with sewage effluent particles are inactivated more rapidly with 0.5 mg of chlorine per liter than with 1.0 mg of monochloramine per liter. However, >7-micrometer particles can have a protective effect against the disinfecting action of chlorine.