A Study on Behavior of Substrate Degradation, Interaction of the Anaerobic Bacterial Groups and Upgrading of Process in Anaerobic Digestion

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The degradation characteristics of waste activated sludge (WAS), cellulose and the complex sludge in anaerobic digestion were investigated by conducting the batch and continuous experiments at 35ﾟC by this investigation, the following conclusions were reached : (1) the WAS was difficult to be degraded, compared with the cellulose and the complex sludge which composed of WAS and cellulose ; (2) the digester gas production and percentage of methane from complex sludge were significanthly affected by the composition of sludge ; (3) the rate-limiting step of overall process in anaerobic digestion of WAS and complex sludge, the hydrolysis rate of degradable particulate organic matter is expressed as a linear equation.Through the thermal pretreatment, the anaerobic degradability of WAS and the gas production from WAS were greatly increased, and the retention time necessary for anaerobic digestion was possible to be by 5 days. The optimum pretreatment temperature and pretreatment time for upg … More rading of anaerobic digestion of WAS were 170ﾟC and 60 minutes, respectively.Effects of temperature and hydraulic retention time (HRT) on the characteristics of acidogenesis in anaerobic digestion were investigated using anaerobic chemostat-type reactor which soluble starch was fed as a substrate. it was elucidated that the degradation efficiency of substrate, the composition of volatile fatty acids produced and the distribution of acidogenic bacteria and methanogenic bacteria were significantly affected by the temperature and HRT.The effects of substrate composition and high volumetric loading rate on the characteristics of substrate removal and biofilm formation in methanogenic phase of anaerobic two-phase digestion were investigated by using laboratory-scale anaerobic fluidized bed reactor. It was found that the substrate removal efficiencies were increased and the biofilm formation was accelerated by adding a small quantity of yeast extract or glucose to the substrate. While the loading rate increased to 30 kgCOD/m^3 day, the substrate removal efficiencies were also high as 98.8%. Less