Study Of Novel MABR And Its Application In Wastewater Treatment

Membrane-aerated biofilm reactor?MABR?is mainly composed of two components,i.e.the membrane modules and biofilm,which integrates the traditional biofilm technology and the membranetechnology for gas separation.When intra-membrane air pressure is below the bubble point,air is supplemented to the biofilm under the bubbleless aeration pattern.Microbes inside the biofilm utilize the pollutants?organic carbon,nitrogen,phosphorus,etc.?for metabolism and proliferation,which improves the water quality of the wastewater simultaneously.MABR is characterized by the bubbleless aeration,counter-direction mass transfer,and biofilm stratification.Thus,MABR has unique advantage in the filed of wastewater treatment.1.A hybrid MABR system,integrating the MABR process and the deep treatment of ozone-biological activated carbon?O₃-BAC?,was constructed and applied in the treatment of oil-field wastewater.Effects of aeration pressure and feed flow rate of MABR and retention times of O₃-BAC on the systematic performance were investigated.Results showed that the effluent concentrations of COD,oil contents,total nitrogen?TN?and ammonia nitrogen?NH₄⁺-N?were 45 mg/L,2.7 mg/L,6.8 mg/L and 2.8 mg/L respectively,under the optimal conditions,achieving the requested discharge standards of oil-field wastewater.In this study,it proved that hydrolytic acidification and aerobic oxidation could be simultaneously completed during the same MABR process,which improves the removal efficiency of oil-field wastewater.As calculated,in the BAC process,only 25.2% of organic matters remained on the activated carbon and the others were degraded by the microbes of the BAC.Comparing with traditional activated carbon,BAC could greatly prolong the usage period of the membrane in this study.Therefore the hybrid MABR process is a promising technology for oil-field wastewater treatment.2.A laboratory MABR,inoculated with ADB350M?the engineering bacteria on degrading petroleum hydrocarbon?,was developed to process oil-contained seawater pretreated by rhamnolipid.Effects of the rhamnolipid/oil ratios,nitrogen and phosphorus additions,aeration pressures and setup rotation velocities on the MABR performance were investigated.Results showed that under the optimal conditions,effluent concentrations of COD,oil content,total phosphorus?TP?and TN were 39 mg/L,2.3 mg/L,0.29 mg/L and 1.9 mg/L,respectively.Throughout the treatment,the ADB350 M exerted good adherence to the aerated membranes,which reduced their loss in comparison with spreading engineering bacteria directly into seawater.Rhamnolipid addition was conducive to improve the biofilm hydrophobicity by changing the polysaccharide/protein ratios of extracelluar polymeric substances?EPS?.In conclusion,the MABR system substantially removed oil and other pollutants in the oil-spilled seawater.3.This study investigated the feasibility of enhanced MABR for the surface watertreatment.Membrane module suitable for efficient aeration and microbial adhesion was designed.In Phase 1,only half of the membrane modules were aerated to facilitate the formation of stable biofilm with aerobic and anaerobic microbial community,achieving the simultaneous hydrolytic-acidification,aerobic oxidation,and nitrification-denitrification effects.In Phase 2,all the membrane modules were aerated and polyhydroxyalkanoate?PHA?was utilized as carbon resource to promote the microbial growth.N itrogen and phosphorus were bio-transformed concurrently.At the 28 th day,the enhanced MABR was entirely lifted out to prevent pollutants further releasing back into the water.During the surface water treatment,the average effluent concentrations of COD,UV254,NH₄⁺-N,TN,TP and turbidity were 35 mg/L,0.03 cm^-1,0.21 mg/L,1.5mg/L,0.23 mg/L and 3.12 NTU,respectively.Conclusively,effective performance of the enhanced MABR was attained.