抄録
The objective of this study was to enhance the process of granulation in the anaerobic reactor using the method of over loading. At over loading, the oversupplied substrate is supposed to stimulate the microorganisms to excrete extracellular polymer, which acts as a bridge between the small flocculent sludge particles. It helps to develop the granular sludge so that the granulation process could be achieved in a relatively shorter time. In this study, the over loading was applied according to the thought that the biomass can be kept better at a fixed flow rate while the coagulation of sludge can be easier at unchanged substrate concentration. As a result, granulation was achieved in about 30 days while about 90 days were necessary when the reactor runs at the ordinary low loading rate. It is found that the content of extracellular polymer increased after the over loading was applied and then decreased gradually after the formation of granular sludge. The specific gravity of wet sludge changed in the same trend with the variation of extracellular polymer content in the sludge. Besides, the sludge particle size distribution changed from a normal distribution to a bimodal distribution and the coefficient of variation came to be a quantitative parameter to assess granulation at over loading condition.
