The Treatment Of Azo Dye Wastewater By The Membrane Bioreactor

Azo dyes are widely used for printing,papermaking,cosmetic industries as well as textile dyeing because of their chemical stability,easiness of synthesis,and versatility.Azo dyes with complex structures and high toxicity are usually difficult to degrade.So the wastewater with Azo dyes do harm to environment continuously.The treatment of azo dyes in wastwater is very difficult.Besides that,because armatic amine is the precursors and the degradation products of azo dye has carcinogenicity,the degradation of azo dyes is received much concern.In recent years,membrane bioreactor(MBR) which is a new wastewater treatment process as a combination of traditional activated sludge process and membrane has great advantage in decoloration of azo dyes.It has some advantages such as small floor area,good effluent quality and little excess sludge,but the membrane fouling is always a main obstacle to its extensive application.A lot of study show that the problem of energy consumption is the problem of membrane fouling actually.According to the report,the extracellular polymeric substances(EPS) of activated sludge is an important reason of membrane fouling.Using Acid OrangeⅡas an example,this paper studied the degradation of its by genetic engineering bacteria Escherichia coli JM109 in anaerobic membrane bioreactor.The results show that genetic engineering bacteria Escherichia coli JM109 had a good degradation to Acid OrangeⅡin anaerobic condition.Second,this paper also studied the metabolic behavior of genetic engineering bacteria Escherichia coli JM109 and the relationship between the metabolic behavior and the membrane fouling in anaerobic membrane bioreactor.It had been found that the more metabolic behavior was vigorous,the more extracellular polymeric substances were producted and the more membrane fouling was serious.At the same time, the operational conditions on the membrane fouling were experimented.The HMBR system was operated intermittently with the the proper suction time was 6 min,halt time was 5 min, aeration intensity was 6 m~3/(m~2·h),the concentration of suspended sludge was 2 g/L and the attach was 6 g/L,membrane flux was 20L/(m~2·h).And net aeration,water backwash and chemical washing take the TMP lower effectively.