Assessment of the Evolution and Efficiency of a Full-Scale Sewage Sludge Composting Process

The evolution of a compost, consisting of sewage sludge, straw and sawdust developed under full-scale conditions, was studied. During the composting process, the following parameters were analyzed: water-soluble C, UV-vis measurements, ash content, C/N ratio, humic substances, C mineralization and seed germination. The objectives were to select among the studied parameters those that could be used to monitor the process and to decide when the material could be considered ready to use in terms of stability and maturity. The results indicate that C mineralization, ash content and the absorbance at 665 nm could be used in the future for compost monitoring. Moreover, the compost material would be ready to use after approximately 40-50 days of composting.