Behaviour of Main Microbiological Parameters And of Enteric Microorganisms During the Composting of Municipal Solid Wastes and Sewage Sludge in A Semi-Industrial Composting Plant

This study was focused on the microbiological aspects of composting and on the behaviour of main prevalent microbial communities (non-pathogenic and selected pathogenic bacteria) during the composting process of municipal solid wastes and sewage sludge in a semi-industrial composting plant. Results showed that the dehydrogenase activity and Biomass C / Biomass N ratio showed a noticeable increase in the two windrows W1 (100% of municipal solid wastes) and W2 (60% of municipal solid wastes and 40% of dried sewage sludge) during the thermophilic phase (≥45°C for 100 days) and marked a high microbial activity during this period of the composting process. During the thermophilic phase, the removal of faecal indicator bacteria is in order of 2 Ulog₁₀, and a total absence of Staphylococcus aureus and Salmonella was observed. The re-emergence of faecal indicator bacteria at the end of the composting progress (cooling step) could constitute a major problem for the agricultural use of compost.