Research On The Key Technologies Of High Efficiency Anaerobic Digestion For Municipal Sludge In Guangzhou

Municipal sludge contains complicated components,and most of them are harmful to the environment and human health.How to fulfill the “reduction,stabilization,harmlessness and recycling” is a big challenge for sludge treatment in the world.As the first choice for sludge disposal,anaerobic digestion technology(ADT)can make sludge stabiliable and recyclable effectively.However,direct anaerobic digestion occupies large area,with high running cost and low gas production rate,which limits its application in China.In view of the bottleneck of direct ADT at sludge disposal in Guangzhou,we take advantage of two different thermal pre-treatments on sludge digestion,and investegate the effects of experimental conditions and parameters on the treatment effectiveness via the small-scale and pilot-scale equipments respectively.According to the results,the high temperature(170?)thermal pretreatment-mesophilic anaerobic digestion is suggested for the small-scale study,while an alkali-heat pretreatment technology at 70 ? is for the pilot-scale study.Also,the economic comparison between two technologies is analyzed in this work.The results show that the sludge digestion rate and gas production efficiency can be significantly improved after the pre-treatments technologies,which is beneficial to decrease the volume of anaerobic reaction tank.After the disposal,the contents of sulfide and heavy metals in digestate are effectively degraded,which can meet the requirements of stabilization and harmlessness.The ratio of C/N to C/P in slurry is suitable as carbon source for sewage treatment plant.For municipal sludge in Guangzhou,the average organic content is about or less than 50%,thus a certain proportion of kitchen waste can increase the organic content of the sludge to produce more biogas.In view of the Guangzhou municipal sludge status and economic condition,the high temperature pretreatment-mesophilic anaerobic digestion is more economic and efficient,while the alkali-heat pretreatment technology shows an advantage at disposal sludge with high organic content,such as the mixture of kitchen waste-sludge.In this work,high temperature/ alkali-heat pretreatment-mesophilic anaerobic digestion is developed for the sludge treatment at Guangzhou.The results can provide strong theoretical basis and practical support for the upgrading and spreading of ADT.