Effect of Bulking Agent Ratio on the Physicochemical Parameters of Sewage Sludge Composting

The sawdust was selected as the compost conditioner and the different sawdust content on physicochemical parameters of sewage sludge composting was studied.The results indicated that the proportion of 3.5∶1.0(m∶m) and 4.0∶1.0(m∶m) between sludge and sawdust during composting can achieve the highest temperature and the duration of high temperature and treatment the VS content compared to 3.0∶1.0 and 5.0∶1.0;where the proportion of 3.5∶1.0(m∶m) and 4.0∶1.0(m∶m)were serious,with the decline of 63.25% and 53.05% respectively. The nitrate nitrogen content performed to decline firstly and then increase. However ammonium nitrogen content changes just on the opposite trend. The p H,EC and GI during composting all met the requirements of harmless at the end of composting. Taking material cost and the nitrogen loss into account,it is recommended that 4.0∶1.0(m∶m) was the optimized ratio in the process of sludge and sawdust compost.