Study On Removal Of Nitrogen And Phosphorus Of Wastewater Treatment In The Dual Chamber Microbial Fuel Cell

Microbial fuel cells(MFCs)are the new type of bioelectrochemical device,which can directly convert chemical energy of biodegradable organic matter into electrical energy.In this research,the effects of the concentrations of inorganic carbon and dissolved oxygen(DO)in the cathode on microbial nitrogen removal were studied by using dual chamber MFC without pH buffer and external circulation device to improve the removal of pollutants and electricity generation performance.Two types of MFC with chemical or biological phosphorus removal in the cathode were constructed for simultaneous nitrogen and phosphorus removal.The main results are as follows:In the nirtogen removal MFC,nitrifying bacteria were inoculated in the cathode.The change of total nitrogen in the reactor was monitored.It was found that the electricity producing bacteria in the anode chamber had denitrification effect.With the increasing concentration of NaHCO3 and DO,the electricity production,power density and denitrification efficiency were all increased gradually.When NH4+-N was 200 mg/L,NaHCO3 was 1 g/L and DO was 6.8 mg/L in the influent,the removal rate of NH4+-N can reach 99.89±0.12%after 60h of operation.After 82h of operation,the removal rate of total nitrogen can reach 82.29±0.12%,and the maximum power density was 149.76 mW/m2 when the current density was 130.27 mA/cm2.By SEM and 16S rDNA analysis,we found Thauera,pesudomonas which can simultaneous nitrogen removal and electricity production and Nitrobacter,Nitrosomonas,Nitrosospira which have the single function of nitrogen removal.Compared with the traditional biological denitrification and related MFC nitrogen removal research,this method does not need pH buffer solution and external circulation device.Through the anion exchange membrane to balance the pH in the reactor,it can simultaneously produce electricity and remove nitrogen,and improve the oxygen utilization rate in the cathode.In the chemical phosphorus removal MFC,PO43--P was 102.86±15.29 mg/L,and NH4+-N was 200.90±9.27 mg/L in the influent.After 17 hours of operation,the removal rate of PO43-P and NH4+-N were 65.19±3.21%and 18.65±9.72%,respectively.In the biological phosphorus removal MFC,PO43--P was 109.42±12.67 mg/L,and NH4+-N was 205.21±12.27 mg/L in the influent.After 53h of operation,the removal rate of PO43--P and NH4+-N were 57.63±2.40%and 76.12±0.21%,respectively.The maximum power density was 45.45mW/m2,which was 40.73%lower than that of the chemical phosphorus removal MFC,indicating that the cathode inoculated phosphorus removal microorganism is not conducive to electricity production.Comparing these two kinds of MFC,it is found that MFC can be selected according to the concentration of nitrogen and phosphorus in wastewater.Chemical phosphorus removal MFC with shorter reaction time can be used for wastewater with high phosphorus and low ammonia nitrogen,while biological phosphorus removal MFC with longer reaction time can be selected for wastewater with high phosphorus and high ammonia nitrogen.SEM results showed that a kind of bacteria might be found as anammox bacteria besides the struvite on the cathodic surface of chemical phosphorus removal MFC.Phosphate accumulating organisms(PAOs),ammonia oxidizing bacteria(AOB)and nitrite oxidizing bacteria(NOB)could be found on the cathodic surface of biological phosphorus removal MFC.