Studies On A Membrane Biofilm Reactor For VOC Contaminated Air Treatment

The membrane biofilm reactor combines conventional microbial technology for waste gas treatment with membrane technology, which not only has advantage of environmental protection due to biological method, also is characterized by high specific surface area as mass transfer interface provided by membrane material, so effect of biological degradation is enhanced greatly. At present, the membrane biofilm reactor is a kind of the most developing potential in all treatment methods of waste air. After reviewing the previous studies, the paper emphasizes experimental research and mass transfer process analysis in membrane biofilm reactor, and mainly including aspects are as follow:In this paper, A System of flat composite membrane biofilm reactor for volatile organic compound (VOC) treatment has been designed. The experiment makes activated sludge, which was used to treat waste water, circulate flow along liquid side to form a biofilm on the surface of dense layer in the composite membrane. Waste air with VOC passes through gas side (support layer), then permeate horizontally and get through the membrane and finally be biodegraded by microorganism biofilm.By analyzing the experiments on MBfR without biofilm, the mass transfer resistance, including gaseous film, membrane and liquid film, was obtained which provides the experiments of MBfR with biofilm key parameters.Through studying the forming of the biofilm and the adaptation process of biofilm degrading toluene, the feasibility of biofilm form on flat composite membrane outside surface using sludge circulating flow and rapid adaptability of MBfR for degrading VOC is provided.In the experiments, operational parameters, such as gas residence time, toluene inlet concentration, and pH value in liquid phase, are changed to investigate the effect on degrading results, including removal efficiency, elimination capacity and mass flux, then, the regularities and optimal operation parameters are obtained.The operation of the system of MBfR lasts for a period of 5 months successfully, which shows that the system of MBfR is steadily for long period running and has strong resistance impact loading and recovery capability. VOC mass transfer process is analyzed in MBfR, A mass transfer kinetic model of MBfR is established. By comparison of model and experimental results, the reliability of model was proved. Based on the model, the effect of MBfR by biofilm parameters was analyzed.