Study On The Nitrogen Removal And Membrane Fouling Characteristics Of A Membrane Bioreactor Couple With Microbial Fuel Cell System

Membrane bioreactor is an effective technology in sewage treatment, but it haspoor efficient in TN removal, meanwhile membrane fouling is serious, thoseshortage limit its development; While the MFC could use NO₃^-as electronacceptor,use electron from anode as electron donor to remove nitrogen. In thisstudy, a new process combined MFC and MBR was established,firstly,it canremove nitrogen effectively, then it also can modify the property of the mixed liquorand mitigate membrane fouling.Compared with conventional MBR, this study discussed the characteristics ofwastewater treatment and electricity production. The result show that the combinedMFC-MBR has higher efficiency in ammonia nitrogen and COD removal, bothreached88%and99%, it’s as the same with conventional MBR. While the newprocess improve the efficiency of TN removal, making the rate of TN removalreach69%,14%higher than the conventional MBR, during the process of nitrogenremoval, the traditional denitrification play a lead role. Another advantage of thecombined MFC-MBR is the system can recycle electrical energy during waste watertreatment, the maximum power density reach to0.79W/m³.Different operation condition can lead different effect of water treatment. Thework shows that when increasing the concentration of COD, the effluentconcentration of COD and NH4₊^-N keep stable, while the rate of COD,TN removalincrease form79.45%to91.29%.67%to84%, respectively. The research also findthat higher COD load reduce the maximum power density of the system, when theconcentration of COD increase from200mg/L to500mg/L, the maximum powerdensity of the MFC-MBR decrease from1.42W/m3to0.84W/m3; The HRT alsocan affect the effect of water treatment, Within4h-8h, with the extension of HRT,there is no significant change in the removal rate of COD, while the removal rate ofNH4-N increased from90.4%to99.4%, TN increased from44.1%to75.3%. HRTalso affect output voltage of MFC, with the extension of HRT, the output voltage isreduced; The change of resistance also can affect the characteristics of electricityproduction and waste water treatment; With the increase of resistance, the effluentCOD and NH4+-N keep stable, while the removal rate of TN decrease slightly, When the resistance increase form50to500, the removal rate of TN decreaseform75.3%to67.2%,and at the same time, with the increase of resistance, OCV ofMFC increase from608mV to832mV, while the maximum power density of thesystem decrease from1.1W/m³to0.89W/m³.The work also study the characteristics of the membrane fouling in the twoprocess, the result indicate that the combined MFC-MBR could modify theproperties of mixed liquor, making a longer operational time. The combinedMFC-MBR has a lower concentration of EPS, higher particle size（239.5μm） thanthe conventional MBR （91.7μm）, meanwhile small particle size of less than50μmdecrease from more than30%to less than10%. Except that, the combinedMFC-MBR also has lower zeta potential（absolute value） and viscosity of mixedliquor. Moreover, The result of FTIR and EEM also show that the main contaminantare carbohydrate and protein.The work demonstrate that the combined MFC-MBR not only can remove TNeffectively, but also can modify the the properties of mixed liquor, making a longeroperational time.