Study On The Efficiency Of Microbial Desalination Fuel Cell In Treaing High Concentration Ammonia Nitrogen Wastewater

Nitrogen is one of the essential and important elements in life on earth.Since the emergence of life on earth,nitrogen has been maintained in balance through the nitrogen cycle.However,with the surge of population and the development of modern industry and agriculture,the nitrogen cycle and nitrogen balance have been greatly affected,which is the trigger for water environment pollution problems such as water eutrophication and water quality deterioration.High concentration(NH3-N concentration > 500mg/L)ammonia nitrogen has obvious inhibitory effect on microbial activity,resulting in effluent quality exceeding the standard.Therefore,when using biochemical processes to treat high-concentration ammonia nitrogen organic wastewater,reasonable pretreatment is required to reduce the impact of ammonia nitrogen on subsequent biochemical stages.Compared with traditional pretreatment methods(stripping method,chemical precipitation method and electrodialysis method),the pretreatment method based on microbial desalination fuel cell(MDC)has the advantages of low carbon emission,energy saving and high efficiency,and co-generation of electricity.In recent years,it has received close attention from scholars at home and abroad.Previous research on microbial desalination fuel cells has confirmed that it has a high desalination effect."The microbial desalination fuel cell system of MDC has been carried out to study the effect of electrode spacing,anode COD concentration,influent ammonia nitrogen concentration and anode substrate type on the removal of high concentration ammonia nitrogen,electrochemical performance and organic matter degradation performance of MDC system.The main conclusions are as follows:1.The mixed bacterial colony inoculation was used to start,and the peak voltage was reached at the 48 th hour.The output voltage during the voltage stabilization period during the start-up phase was between 600-700 m V,and it continued to run for4 cycles(1371h).At this time,it was considered that the MDC was successfully started.2.The electrochemical performance of MDC during operation is good,the maximum power density it generates is 6.04 W/m3,the minimum ohmic internal resistance of the MDC system is 43.07Ω;for ammonia nitrogen removal,the highest ammonia nitrogen removal rate is 99%,and the removal rate is 9.71mg/L;in terms of organic matter degradation performance,the highest removal rate of anode COD is96.4%(300mg/LCOD).3.The optimization analysis of the four key factors affecting the performance of MDC—electrode spacing,COD concentration of anolyte,ammonia nitrogen concentration in the desalination chamber and anode matrix type shows that the smaller the electrode spacing,the better the performance of MDC in all aspects.When the electrode spacing is 3.5 cm,the maximum power density is 6.04 W/m3,the ammonia nitrogen removal rate is 3.17 mg/L,and the COD removal rate is96.4%(300mg/LCOD).Although the reduction of electrode spacing can provide MDC performance,too small spacing will be detrimental to the reactor.Amplification and follow-up maintenance;the smaller the COD of the anode influent,the better the MDC denitrification and electrochemical performance.When the anolyte COD concentration is 200mg/L,the maximum power density is 4.37 W/m3,The removal rate of ammonia nitrogen was 2.98 mg/L,but the COD concentration of the influent water became smaller,and the COD reduction rate was decreasing;when the concentration of ammonia nitrogen in the influent water increased,the denitrification and electrochemical performance of the microbial desalination fuel cell are improved.When the ammonia nitrogen concentration rises to 6000mg/L,the maximum removal rate is 99%,the maximum removal rate can rise to 9.71mg/L,and the maximum power density increases to 5.42 W/m3.However,the high concentration of ammonia nitrogen wastewater in the desalination chamber of the microbial desalination fuel cell will inhibit the activity of electricity-producing microorganisms.compared with glucose,acetic acid The performance of sodium as the anode substrate is better in all aspects,the ammonia nitrogen removal rate is increased by 39%,the maximum power density is increased by 76%,and the maximum COD removal rate is increased by1.8%.In this paper,the microbial desalination fuel cell is applied to the treatment of high-concentration ammonia nitrogen organic wastewater for the first time,and the removal effect of ammonia nitrogen has achieved ideal practical results.Preprocessing provides new methods.The effects of electrode spacing,anode COD concentration,influent ammonia nitrogen concentration and anode substrate type on the performance of MDC were investigated,and the influencing factors were optimized to provide technical support for the stable operation of the MDC system for treating highconcentration ammonia nitrogen organic wastewater.