Optimization of operation conditions for the start-up of a pilot-scale anaerobic biofilm digester treating leachate

摘要

In solid waste management, treating putrid leachate is the most challenging part especially for Malaysia, which has hot and humid weather and raining season throughout the year. Leachate pollution has become a more serious problem these recent years as lack of proper treatment facilities at waste disposal sites affected the quality of water supply due to the penetration of leachate into the groundwater table and its discharge into the rivers. Anaerobic treatment has recently been mentioned by the Malaysian government as the most sustainable technology for waste treatment. Hence, the objective of this study is to optimize the operation conditions for the start-up of a pilot-scale anaerobic biofilm digester at UKM Biogas Site for leachate treatment. In this paper, the results of two separate preliminary operations of anaerobic digestion of leachate are presented. The first operation, conducted with 20-d HRT (daily feed 0.30 m(3)/d) and pH adjustment, was halted after 35 d due to the hydraulic and organic overloads, resulting into system failure. The results were taken into account while commencing the second operation by using the buffering step where small amount of leachate was fed for a month (0.03 m(3)/d for the first week and 0.06 m(3)/d for the rest weeks), with no pH adjustment. This buffering step was conducted to enable the microbes to acclimatize to leachate's low pH and its high organic contents. This step was proven better as parameters observed (pH, total suspended solids, volatile suspended solids, chemical oxygen demand, NH3-N, total volatile fatty acids) showed more consistent values than those of the first operation.