Performance of co-composting waste activated sludge and aged refuse

This study was performed to investigate the effects of aged refuse (AR) as an amendment on waste activated sludge (WAS) composting dynamics. Four dosages of AR (5%, 10%, 15% and 20%, on WAS dry weight basis) were amended to WAS for composting during a 36 d period. Cornstalks were added at 15% (of total wet weight of WAS) to improve the co-composting process. Results show that appropriate AR proportion could rapidly initialize the co-composting process, enhance organic content for biodegradation, and increase the humification degree during composting. Moreover, AR significantly decreased total nitrogen losses and plant toxicity. The maturity parameters indicate that compost with AR became more matured and humified within 36 d of composting, with the maturity parameters being within the permissible limits of organic farming in contrast to the control without AR.