| The twelfth "Roadmap for Five Years" of our nation conveys important information:the zero pollutant discharge is a key goal of the future wastewater treatment in China. Among all the potential zero-discharge technologies membrane-based technique is the most promising one. A membrane bioreactor (MBR) combines the advantage of both conventional biological process and membrane technology and, hence, will be the first choice in future to meet the zero discharge. In recent years, anaerobic technique returns to the hot spot of environmental engineering, and the anaerobic MBR (AnMBR) also draws more and more attention. In this thesis, the impact of two key factors (substrate and temperature) to AnMBR was investigated based on three criteria:COD removal performance, membrane fouling and its control, and sludge characteristics.Two types of carbon source were selected:sole VFAs and VFAs+glucose. The results showed that AnMBR had the similar COD removal capacity regardless of different substrate types. The combined substrate (applied to 2#MBR) caused more severe membrane fouling to AnMBR than the sole substrate (applied to 1#MBR). The fouling rate of 2#MBR was nearly the 4 times higher than that of 1#MBR. The higher content of hydrolytic bacteria may cause such severe fouling. The cake layer is the key reason decreasing the efficiency of AnMBR on one hand, but on the other hand the cake layer plays a role as the "second stage of filtration", which effectively avoid the penetration of small particles into membrane holes. In addition, the sludge characteristics determine the precipitation rate of small particles to the surface of membrane, and hence influence the critical flux indirectly.Two temperatures were chosen to assess their impact on the AnMBR:30℃(3#MBR) and 55℃(4#MBR). The results showed that the thermophilic AnMBR has higher COD removal capacity than the mesophilic one since the biomass has the higher activity in degrading soluble and insoluble organic matter under high temperature. However, the biomass yield of the thermophilic AnMBR is 35% lower than the mesophilic one. Severe accumulation of acetic and propionic acid was observed in the mesophilic AnMBR probably due to the overload of organic matter. The sludge viscosity under high temperature is much lower than mesophilic condition and, hence, the cake layer of 4#MBR is less than 3#MBR.To investigate the effective way to control membrane fouling, the applied flux should be always under the critical flux. The penetration of small particles into the membrane hole is a long-time process, causing the irreversible membrane fouling. It is useful to keep the applied flux low and back wash the membrane in order to avoid sever irreversible membrane fouling. From a microcosmic perspective, a physical clean only wash out the loose cake layer on the membrane surface. A membrane module after chemical clean still has an 18% increase in filtration resistance compared to a virgin one, indicating that even the chemical clean cannot completely remove the small particles. This study also proves that no matter in what substrate or under what temperature, the increase of aeration rate only has very limited positive influence to enhance the critical flux of the membrane module. Interestingly, the high aeration rate makes small particles prone to attach or precipitate onto the membrane surface and cause severer membrane fouling.
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