Co-removal Of Carbon And Nitrogen Contaminants In Microbial Photoelectrochemical System

In view of the shortage of water resources and the problem of water pollution is becoming more and more serious,and the state of the sewage treatment plant discharge standards are becoming increasingly stringent.For organic pollutants and nitrate coexist in the urban secondary effluent at present,we have to pay instensive attention to the development of adapted advanced technology for efficient carbon and nitrogen removal.This study introduced the titanium dioxide semiconductor photocatalytic material into the microbial electrochemical system,constructed the microbial photoelectrochemical system,confirmed the system can achieve the function of carbon and nitrogen contaminants removal.The different effects on the removal of nirate and electrochemical performance of the system were investigated.The microarganisms of nitrate with humic acid(HA)or bovine serum(BSA)were investigated.Finally,the disinfection performance were evaluated.The main conclusions are as follows:The biological denitrification process of nitrogen removal by light driven was realized by coupling the self-made Ti O2/Ti photoanode with the denitrifying biological cathode.The performance of denitrification cathode is positively related to the system current density,and the current efficiency of the system is approaching 100% with the increase of the system current density.By reducing the distance of the light source and increasing the number of electrodes,which can effectively improve the system current.The current of 0.5 cm is 2 times to the light source of 2.5 cm,and the current of 4 pieces is 1.5 times of the one piece,the higher current can improve the system denitrifying load;when the concentration of nitrate is below 30 mg/L,with the increase of the concentration,the current and nitrogen removal load increases.Extending the HRT can reduce the accumulation of intermediate products,and in this study the more suitable time is 9 h.Using humic acid and bovine serum albumin as the representative of the soluble microbial products in secondary effluent,which confirmed the system can removal of carbon and nitrogen at the same time,and nitrogen and carbon has interaction.In addition,the coupling system can achieve sterilization process.The coupling of the biological cathode and the photoanode is superior to that of the biological cathode and the photoanode alone.When humic acid and NO3--N coexist,the increase of the humic acid concentration result in the current and the denitrification ability decrease.With the increase of NO3--N concentration,the effluent of humic acid in the system decreased.When the BSA and NO3--N coexist,and with the increase of BSA concentration,the current of the system decreases from 4.37 m A to 1.3 m A.The bacterial can use BSA as the denitrification source and the process of biodegradation of BSA will result in the accumulation of NH4+-N.The ammonia nitrogen can be removed by photocatalytic reaction in the photo-anode chamber.With the increase of nitrate concentration,the current of the system increases and the removal efficiency of the effluent can be improved.At the same time,the efficiency of photo-anode sterilization is about 95%,the disinfection effect is good.