PRINCIPLES OF WET WEATHER HIGH-RATE DISINFECTION EXPERIENCES FROM THE 1970S TO THE PRESENT

Disinfection of wastewater commonly follows secondary treatment and has been practiced in this country since the early 1930s. As early as 1934, a classification scheme was developed to categorize the bacteria quality of Connecticut's shore bathing beaches. This method ultimately was adopted by the Public Health Association in 1943. In 1968 the U.S. Department of interior proposed the use of the total coliform (TC) indicator in determining swimming area suitability; shortly thereafter the Department proposed the use of the fecal coliform (FC) bacterial indicator in lieu of TC because it was more indicative of fecal contamination and less subject to variation. A study by the U.S. Public health Service on the Ohio River identified 200 FC/100 ml as being an appropriate threshold density of health risk. Most states adopted this criterion as a standard in 1968. It was about this same time the influence of wet-weather on health risk was being recognized.