Study On The Operating Characteristic Of Submerged Membrane Bioreactor

The membrane bioreactor (MBR) is a new technology combining membrane technology with wastewater treatment. Through the experiment of using MBR to treat wastewater, we studied the operational performance of membrane bioreactor with sludge discharge and no sludge discharge and discussed the influencing factors of membrane fouling and the method of reducing membrane fouling rate.In order to investigate the operating characteristics of MBR with no sludge discharge, we took hollow fiber membrane as the core and artificial sewage as the study object, designing and operating a membrane bioreactor device (MBR) of 19 liters treated wastewater. System operated properly 125 days with taking a way of flooding water continuously and pumped or suctioned intermittent with vacuum pump. Through the experiment, we found the sludge density of MBR grew with the run-time extension and stabilized at last with the influent concentration and hydraulic retention time keeping unchanged. The quality of water leakage became better and better with the sludge density growth. Because the dissolved oxygen of MBR pond reduced gradually with the sludge density rising. It need increase aeration intensity constantly in order to maintain constant dissolved oxygen systems.In order to investigate the operating characteristics of MBR with sludge discharge, an orthogonal analyzing model of MBR implementation was established with water quality (COD concentration, nitrogen concentration) and membrane fouling rate as the index, sludge concentration, dissolved oxygen and hydraulic retention time of the orthogonal test as the factors. The results showed that the sludge concentration had severe effect on membrane fouling and the quality of water leakage, but less effect on dissolved oxygen and hydraulic retention time. In addition, the optimal operation performance was recommended from effluent qualities and membrane fouling.During the study of membrane contamination, the system controlled effluent through the operation of constant pressure and constant-current. Membrane fouling rate rose with the rising sludge concentration regardless of taking every way to control system effluent, In addition, aeration intensity also had effect on membrane fouling. One hand, lower aeration intensity increased the speed of material that gathered particulate matter in the water mixture and macromolecules to the membrane surface, another hand, although the higher aeration intensity increased the effect of turbulent flow, it made the sludge more minor and increased membrane fouling.In order to overcome the shortcomings of MBR and compare it with the before, we optimized the aeration system, because MBR treated high concentration wastewater was easy to be plugged, The results showed that the improved aeration system had conspicuous effect to slow rate of membrane fouling.Basing on the small test of submerged membrane bioreactor and uniting the actual project case, we investigated the economic viability of membrane bioreactor and put forward suggestion for routine maintenance and management of the membrane biology reactor.