The importance of Evaluation of microorganisms in raw sewage sludge intended for agriculture

Abstract

Abstract The present study was conducted to determine the microbiological characteristics of sewage sludge from five waste-water treatment plants (WWTPs) in eastern Algeria and to assess the efficiency of drying beds in lowering the microbial load in this sludge, which is typically used in agricultural fields. We chose the five most significant waste-water treatment facilities in Algeria's Eastern area to carry out this study. Where we have counted harmful microorganisms (Salmonella, Clostridium), and examined parasites. Total coliforms, fecal "E. coli" and fecal streptococci were used as indicators of fecal contamination. The obtained results indicate that the examined sewage sludge is a rich source of microorganisms, particularly bacteria of fecal origin, especially during the months of high temperature (Spring, Summer), and moor particular in the sludge of medium age (more than 1 month). As a result, we have reported a significant presence of anaerobic sulfate-reducingria (ASR), Salmonella spp., and E. coli. We also observed that this sludge included parasites, ranging from protozoa to helminth eggs. We may draw the conclusion that even if the microbiological load in the sewage sludge significantly decreased after treatment in the drying beds, the hazards associated with the spread of this sludge must be managed by adherence to a set of exact guidelines. This study allowed us to determine the microbiological properties of sewage sludge, through which we can reduce the risks or definitively eliminated, which allows the possibility of valued them in the agricultural sector by avoiding all possible environmental risks and even on health public.