Impact Of Temperature On The Performance Of A/O-MBR And The Membrane Follution

Membrane bioreactor (MBR) is more and more widely applied to the sewage treatment industry in rencent years. The membrane fouling is one of the main factors which restrict the widely development and application of MBR, so the research on\slowing down the rate of membrane fouling is of great significance in reality, As the main section of the reactor, the microorganisms community structure and characteristics of the metabolic products have a great influence on the membrane fouling. Meanwhile, the temperature is an important ecological factor which has a great influence on the growth and metabolism of the microorganisms.This study used Anoxic/aerobic-membrane bioreactor as experimental object and the temperature as the main changing parameters, running the A/O-MBR to process the artificial sewage under30℃,20℃and10℃respectively. The aim of the study is to monitor the content and composition of extracellular polymers (EPS) in mixed liquor and membrane module filter Cake layer of aerobic pond under different film pressure in a membrane pollution cycle, and to explore the microbial community composition in the A/O-MBR system using T-RFLP. At the same time, we intend to observe the microscopic structure of the membrane silk surface to examine the occurring process of the membrane fouling by Atomic Force Microscope (AFM). The relationship among the change of the microbial community, EPS and the process of membrane fouling would also be probed.The results show that the change of temperature has little influence on COD removing. When the temperature is20℃or30℃, A/O-MBR works very well on the removal of ammonia-nitrogen and nitrogen. But the nitrogen removal effect of A/O-MBR gets much worse when the temperature is10℃,. The A/O-MBR membrane pollution cycle approximately is23-31d when the temperature is20℃or30℃, and it is shorten seriously to5-6d when the temperature gets to10℃. The low temperature has a terribly influence on membrane fouling development and nitrogen removing of the A/O-MBR. The membrane silks are covered by heterology materials and membrane pores are blocked during the A/O-MBR operation process, which is the directed reason for the increasing of membrane press and the occurrence of membrane pollution. When the temperature is30℃, the main affected factor of A/O-MBR membrane fouling is SMP which produced in Cake layer. When the temperature is20℃and10℃, the main affected factor of A/O-MBR membrane fouling is Cake layer.In the process of A/O-MBR working, the microbial communities are inconsistent in mixed liquor, Cake layer and the surface of membrane silk of aerobic pool. The dominant species occurred inconsonantly and there exits the community succession process. There is an obvious difference about microbial community composition in the A/O-MBR system under different temperatures, and the microbial species which have great contribution to the membrane fouling are also different, Rhizobium, Thiothrix sp. and Zoogloea Ramigera caused membrane press increasing quickly when the temperature is30℃,Thiothrix sp. and Myxobacterium do obvious contribution to film fouling developing quickly under20℃, when the temperature turns to10℃, the bacteria species who have a great effect on the membrane fouling developing quickly are Thiothrix sp. And β-Proteus. There is a significant relationship between microbial community composition and the EPS.