Approaches to Recultivation of Sewage Sludge Cards of Biological Treatment Facilities of the City of Kazan

Abstract

Quantitative, physicochemical, toxicological and microbiological characteristics of sewage sludge accumulated on sewage sludge cards of Municipal Unitary Enterprise Vodokanal in Kazan are determined. The use of sewage sludge for land restoration and as organic fertilizers is limited by the high content of bacteria of the group of Escherichia coli and heavy metals. Considering the significant volumes of sewage sludge, a method for their restoration directly in sewage sludge cards using quicklime and zeolite is proposed. Experiments have shown that the introduction of calcium oxide and activated zeolite in the amount of 2.5–5.0 % and 20–30 % by weight of the raw sludge, respectively, stops the fermentation processes, provides disinfection, dehydration and structuring of sewage sludge, promotes the immobilization of heavy metals. The intensity of ammonia release into the atmosphere was determined for different technological parameters of sewage sludge treatment.