Study On Purification Of Gaseous Xylene By Membrane Bioreactor

Air pollution is more and more serious with the development of the industry in recent years.As a kind of pollutants,VOCs are not only virulent and pungent but also do great harm to the environment and human health, therefore, more and more attention has been focused on the purification and treatment of VOCs.To resolve the problem,several purification technologies including adsorption, absorption,combustion,condensation,membrane separation and biological treatment have been employed for waste gas treatment.The membrane bioreactor which combines membrane sepraration technology and biological treatment technology, not only bonds the advantages of other traditional biological methods but also improves the reaction conversion and processing capacity effectively.In this paper,submerged menbrane bio-reactor were studied. Under the condition of the steady state,operational parameters,such as gas residence time,xylene inlet concentration,p H value in mixed liquor were changed,and their effects on degrading results including degrading efficiency,biochemical degradation were texted.The operation of themembrane bioreactor lasted for about 5 months and the experimental results show that:the outlet concentration and biochemical degradation are correlated with the inlet loading.In the same condition,microorganisms could work best when the p H is 7~7.5.Degrading efficiency increased with residence time prolonging.The maximum removal rate of xylene can reach 98% in the reactor. When the temperature is normal,the maximum biochemical degradation of submerged menbrane bio-reactor can reach 200 g/(m3 · h),however, the sprayed menbrane bio-reactor can only reach 64g/(m3·h).About 14% of the products that transformed from xylene by the microorganisms were converted to CO2,others were used for the growth of microorganisms for itself.In the process of purifying the waste gas containing xylene by using membrane bioreactor,the related kinetic model and simulation of the“Adsorption-Biofilm theory” and“Absorption-Biofilm theory”were investigated in this study.By contrasting the lab test data and the simulated data,the results indicated that the “Adsorption-Biofilm theory” results of the model was better,and the relative coefficient of the outlet concentration is 0.9309.