Studies On A Membrane Bioreactor For Biodegradation Of VOCs Contaminated Air

The membrane bioreactor combines the bioreactor with the membrane technology, whichnot only has advantage of environmental protection due to biological method but also ischaracterized by high specific surface area as mass transfer interface provided by membranematerial, so the effect of biological degradation is enhanced greatly. At present, the membranebiological process is one of the most developing potential treatment methods of industrywaste gases. After reviewing the previous studies, the paper emphasizes experimentalresearch and mass transfer process analysis in membrane bioreactor, main study contents areas follows:In this paper, an experimental system of vinylidence difluoride (PDVF) porous hollow fibermembrane bioreactor(HMBR) for treating volatile organic chemicals (VOCs) has beendesigned, The experiment makes use of sludge circulating flowing along shell side (theexternal surface of membrane fiber) to form a biofilm which grows on membrane fiber. Aircontaminated with VOCs passes through tube side (the lumen of micro porous hollow fiber),then permeates horizontally the membrane pores and finally is biodegraded by the biofilmwhich is appressed on the hollow fiber's outside surface.By studying the forming of the biofilm and the adaptation process of biofilm degradingtoluene, it shows that the biofilm formation on PVDF hollow fiber outside surface usingsludge circulating flow is good and the adaptability of HMBR for degrading VOCs is rapid.In the experiments, operational parameters, such as gas residence time, toluene inletconcentration, velocity of liquid phase flow and pH value in liquid phase, are changed, andtheir effects on degrading results including degrading efficiency, elimination capacity andmass transfer rate are tested experimentally, and then the regularities and optimal operationparameters are obtained.The operation of the system of HMBR lasts for a period of 8 months successfully. It showsthat the system of HMBR is steadily for long period running and has a good performance ofresistance impact loading and recovery capability.In this paper, HMBR is also used to deal with trichloroethylene (TCE), which has sometoxicity for the microorganism cells. With the increase of gas residence time, the degradingefficiency of TCE will be improved, and the maximum degrading efficiency is about 21ï¼….VOCs mass transfer process is analysised in HMBR. A mass transfer kinetic model ofHMBR is established and the optimum thickness is attained by numerical simulation. Basedon the model, the degrading efficiency of toluene is predicted by using this method.