Technology Analysis And Post-treatment Process Study On Domestic Sewage Purification Biogas Digester

Domestic sewage purification biogas digesters have a lot of advantages, such as decentralized investment, no consumption of power, low cost of running and saving lands etc., gradually becoming a primary technology of sewage decentralized treatment systems in the South of China. However, this technology has still some problems, the effluent can't meet the sewage discharge standard. It shoud be propitious to upgrade the capacity of treating wastewater and to promote the application by reinforcing studies on optimizing this technology or adding post-treatment equipments.The paper comprised two aspects of studies: (1) techlonogy analysis on the five representative designs selected from tens of sewage purification biogas digesters, which collected from some provinces in China; (2) two experiments, with the laboratory installations of Biological Contact Oxidation and Simulative Natural Ditch, had been done to find out how their efficiency was, as post-treatment process for treating sewage digested effluent .The main results were summarized as follows:(1) The five biogas digesters selected represented the general characteristics of sewage biogas purification technology, but they had different parameters. There was random in digester design, and some important parameters were not chosen strictly. All of these might influence the efficiency of sewage treating.(2) The results of experiments indicated that Biological Contact Oxidation Process could improve water quality very well as a post-treatment method for anaerobically pre-treated domestic sewage. When HRT=12h, COD and Ammonia-nitrogen concentration of the effluent could meet the first grade of Integrated Wastewater Discharge Standard (GB 8987-1996). Its TP could meet the second grade of Integrated Wastewater Discharge Standard (GB 8987-1996), but its TN removal efficiency was still a problem. It also could be found by the tests that TN and TP removal efficiency with intermittent aeration was better than that of continuous aeration.(3) Simulative Natural Ditch were studied in this paper when Simulative Natural Ditch was test as a experimental installation for treating sewage. When HRT=12h, COD concentration of effluent was 90 mg·L^-1 and ammonia-nitrogen concentration of effluent was 23.5 mg·L^-1, the concentration of two indexes met the second grade of Integrated Wastewater Discharge Standard (GB 8987-1996). The removal efficiency of COD and Ammonia-nitrogen was better when temperature was higher. TN and TP removal efficiency of the process was not in evidence.(4) Compare to the performance of two experimental equipments, Biological Contact Oxidation Process was better, that the process, as a post-treatment technology, was fit into large-scale projects. If Simulative Natural Ditch was used as post-treatment technology of little biogas tank, It would be suitable.