膜生物反应器处理甲苯性能及机制

Mechanism and Performance of a Membrane Bioreactor for Treatment of Toluene Vapors

采用膜生物反应器处理甲苯有机废气,研究了进气浓度、停留时间、循环液喷淋密度和pH值对甲苯去除率的影响.膜生物反应器能高效净化挥发性有机废气,甲苯去除率可达99%.适宜运行条件为:pH值为7.2、停留时间为6.4 s、循环液喷淋密度为2.5 m3.(m2.h)-1.采用GC-MS分析出口气样,研究结果表明乙醛酸(C2H2O3)和乙烯基甲酸(C3H4O2)为甲苯生物降解的中间产物.膜生物反应器处理甲苯机制为甲苯气体通过中空纤维膜传质到生物膜,被生物降解为乙醛酸和乙烯基甲酸,然后继续好氧降解为最终产物二氧化碳和水.

The performance of a membrane bioreactor for treatment of toluene as a model pollutant is presented.Effects of toluene inlet concentration,residence time,spray density and pH of liquid phase on the toluene removal rate were evaluated.The experimental results showed that the toluene removal efficiency reached 99%.The optimal pH,residence time and spray density were 7.2,6.4 s and 2.5 m3·（m2·h）-1,respectively.The gas-phase biodegradation intermediate products were acetaldehyde acid（C2H2O3） and vinyl formic acid（C3H4O2）,which were identified by means of gas chromatography/mass spectrometry（GC/MS）.The mechanism of toluene degradation using a membrane bioreactor can be described as the combination of mass transfer from hollow fiber membrane to biofilm and biological degradation.Toluene（C6H5CH3） and oxygen diffused from the gas phase to the wet layer of the biofilm and were then consumed by the microbial communities.Toluene was oxidized to the intermediate organic products such as acetaldehyde acid（C2H2O3） and vinyl formic acid（C3H4O2）,and the intermediate products were then converted to CO2 and H2O through continuous biological oxidation reactions.