Class A Pathogen Reduction in the SSDML Process

Abstract

The agricultural use of sewage sludge is limited by the presence of toxic metals and pathogens. The simultaneous sludge digestion and metal leaching (SSDML) process has been developed to resolve this problem. In the present study, the performance of the SSDML process for the elimination of total coliforms, fecal coliforms, fecal streptococci, and coliphages from sewage sludge was verified by shake flask, laboratory bioreactor, and pilot plant bioreactors. The effect of pH, sludge solids concentration, temperature, and sludge types on the bacterial indicator's removal was evaluated. The results showed that the SSDML process was more efficient than the conventional mesophilic aerobic sludge digestion process for the elimination of bacterial (2.5 to >7.0 log units reduction) and viral (>8.0 log units reduction) indicator microorganisms.