INACTIVATION OF FECAL BACTERIA IN SEWAGE-SLUDGE BY ALKALINE TREATMENT

The efficacy of aqueous alkaline solutions to purify wastewater sludge s destined for agricultural land application was evaluated. Some fecal bacteria were tested as sanitary-quality indices, these included feca l streptococci, which were found to be more resistant than coli-forms. Hygienization within 10 days was obtained with ammonium hydrate at a dose that brought the pH of the sludge to about 10. Such a treatment w as effective above 10 degrees C. The total-bacteria number dropped onl y slightly, so that the sludge retained its potential biological activ ity. The efficacy of the treatment with NH4OH was better than that obs erved with KOH.