Anaerobic Digestion Sludge Composting - Assessment of the Star-up process

The aim of this work was to follow the start-up of the composting process of sludge from the anaerobic digestion of municipal solid waste and to assess the quality of the final product. The temperature profile and dry matter content was registered over 10 weeks. The composting process was monitored by standard physical and chemical parameters and the quality of the final compost was assessed by phytotoxicity and stability assays. The low average temperature values registered during composting suggest over aeration. In addition, all the standard physical and chemical parameters analysed showed slight variations over composting, suggesting that the anaerobic digestion sludge was already a stable raw material. The final compost was not phytotoxic and was stable, but contained some inert materials. Overall, the final compost had quality compatible to be used as soil amendment. Nevertheless, the operational conditions optimization should be carried out to improve its quality