Study On Biological Nitrogen And Phosphorus Removal Properties Of Submerged Electric Field Membrane Bio-reactor And Membrane Fouling Control

As one of potential technology of wastewater reuse, membrane bioreactor (MBR) had been widely using in sewage treatment plants and on-site sewage treatment facilities in some developed country. Membrane module in it can separate solid and liquid perfectly instead of the secondary settler which shows great advantage in wastewater treatment and reuse. But the removal efficiencies of N and P are not satisfied and the membrane fouling is still a problem in MBR yet ,which are obstacles for the development of MBR. Submerged electric field membrane bio-reactor which was an innovative process, introduce electric field technology. Then, electronegativity sludge can be protected from accumulating in the hole of membrane and electric field in biological dephosphorization can come application. But the research about it is still on the phase of beginning .In this paper, the studies are carried out mainly about the operation characteristics , the microorganism characteristics ,membrane fouling control for the system.The results showed the best current density of experiment is determined: 0. 16mA/cm². Filtration characteristics and mechanism of membrane fouling were investigated with MBR mixed liquor. It was found that, the variation of filtration resistance was fit to the standard blocking filtration model in initial 5 min process. The relative flux was in the tendency to the linear decay along with filtration time after 5 min. It can be detected that the decline of flux in submerged electric field membrane bio-reactor is introduced in is more slow than the one in conventional MBR with operation in long time. The electric field is be coming to membrane fouling control, because cubic spline functions can be in submerged electric field membrane bio-reactor and exponential decay Model can be in conventional MBR by mathematical expression in evidence. Membrane flux in the front of 8 days can keep better level of membrane flux in submerged electric field membrane bio-reactor.Electric field is not suitable to the removal of COD and TN. But electric field has negative influence in the removal of NH4+-N. Aggrandizement of electric field has a positive effect, the electric field made more contribution to total phosphorus removal than other organic substances. The aggrandizement of electric field in polyphosphate accumulation could also increase efficiency of dephosphorization. At the last stage of the test, there were rises in the amount of COD, NH₃-N, TN and TP in membrane permeate , it was found that the operation without sludge wastage for a long period affected the performance of biological treatment units. The effluent in submerged electric field membrane bio-reactor could meet with the standard for water reuse basically.The result showed electric field can restrain the growth of filamentous bacterium. Also, electric field has detrimental effects on the operating stability of system. The accumulation inhibition make microbial activity turn low and make sludge accelerate ageing.For further investigating the ability of phosphorus removal of the submerged electric field membrane bio-reactor system, polyphosphate accumulation organisms were isolate and cultivated. Then, growth curve of strain were determined by absorbency.