Performance And Influencing Factors Of Self-forming Dynamic Membrane Coupled Bioreactor For Domestic Wastewater Treatment

Membrane bioreactor is a kind of wastewater treatment process which mainly consists of bioreactor and membrane modules. The activated sludge in the bioreactor could biodegrade the pollutants in wastewater through biological reactions conducted by microorganism. The micro/ultra-filtration membrane modules were used to separate solid and liquid in the activated sludge and obtain high quality effluent by filtration. The high cost of micro/ultra-filtration membrane was an important restricting factor for the wide use of membrane bioreactor. To solve this problem, this study adopted the dynamic membrane filtration technology and developed a submerged self-forming dynamic membrane coupled bioreactor, which uses cheap coarse pore-sized material to replace the micro/ultra-filtration membrane. In this kind of bioreactor, the biomass layer dynamically formed on the material during filtration, i.e. dynamic membrane, plays the main role in solid and liquid separation. The performance and influencing factors of self-forming dynamic membrane coupled bioreactor for wastewater treatment was studied in order to provide theoretical and experimental basis for its practical application. This research mainly covered the three parts: 1) performance of self-forming dynamic membrane coupled bioreactor and function of the dynamic membrane, 2) comparison of aeration mode and coarse pore-sized material; 3) influence of cross flow rate on cake layer formation. The main conclusions are: 1) The dynamic membrane coupled bioreactor could remove organic pollutants and ammonia nitrogen effectively. The dynamic membrane could remove and convert some of the organic compounds and nitrogen in the supernatant. 2) When aeration device was placed below the membrane module, the fouling speed of dynamic membrane was accelerated and the effluent turbidity was high. Performance was better when aeration device was beside the module. 3) Four kinds of coarse pore-sized material were compared. It was found that the effluent turbidity of them was very similar. Flux was higher and the fouling was slower when the material was thinner. 4) The fouled coarse pore-sized material could be effectively cleaned by NaClO(5‰). The solid mass, polysaccharide and TOC content on the fouled material reduced after cleaning. 5) The dynamic membrane could be formed in a short time. Higher the cross flow rate was, quicker the deposition rate of cake layer was and denser the cake layer structure was.