Study On Removal Effect Of Nitrogen And Phosphorus In Farmland Drainage By Microbial Fuel Cell

The total amount of water resources in China is very limited,and the per capita water resources possession is far below the world average.Even in the case of such a shortage of water resources,however,with the development of the economy,the situation of water pollution is becoming more and more serious,which leads to the dual pressure of water resources shortage and pollution.Nitrogen and phosphorus in water body are important factors causing water pollution,because excessive nitrogen and phosphorus entering water body is very easy to cause eutrophication of water body.In addition,the concentration and variation characteristics of these nitrogen and phosphorus pollutants in the drainage ditch are still unclear,and we need further investigation and evidence collection and analysis.In the face of water pollution problems,the previous methods have not been effective,so we need to find new ways to replace them.A microbial fuel cell is a device in which microorganisms oxidize and metabolize organic matter while generating electrical energy.It has the characteristics of wide raw materials,mild reaction conditions and green high efficiency.However,there are still problems such as fuzzy motor production and unreasonable operating parameters,so we need to further study the above issues.This test uses a single-chamber microbial fuel cell device in which the anode and cathode are respectively a carbon brush and a platinum-loaded stainless steel mesh.The inoculated bacteria of the experiment are taken from a lotus pond sludge in the Liangyuan park of Shangqiu city,simulating the nitrogen and phosphorus in the farmland drainage as the anode substrate,and studying the electricity generation characteristics of the microbial fuel cell and the removal efficiency of the pollutants.The effects of pH,temperature,nitrogen concentration and carbon-nitrogen concentration on the performance of microbial fuel cells are investigated.The mechanism of microbial fuel cell production and the efficiency of carbon removal and dephosphorization are discussed.The results show that:(1)In the process of carbon and nitrogen removal and phosphorus removal by single-chamber microbial fuel cell,the temperature,nitrogen concentration and C/N ratio of the anode solution are controlled unchanged,and only the pH value of the anode solution is changed.The output voltage increases first and then decreases with the increase of the pH value.The peak value of the output voltage is 202.11 mV for the treatment of pH=8;The removal rates of COD,ammonia nitrogen,nitrate nitrogen and total nitrogen first increase and then decrease with the increase of pH value.When pH value is 8,the removal rates of COD,ammonia nitrogen,nitrate nitrogen and total nitrogen are the highest,74%,89%,97% and 90% respectively.Therefore,pH=8 can be used as the appropriate pH value for this experiment.(2)In the process of carbon and nitrogen removal and phosphorus removal by single-chamber microbial fuel cell,the pH value,nitrogen concentration and C/N ratio of the anode solution are controlled unchanged,and only the temperature value of the anode solution is changed.The output voltage increases first and then decreases with the increase of the temperature value.The peak value of the output voltage is 183.38 mV when the temperature is 35?.Ammonia nitrogen,nitrate nitrogen,total phosphorus and total nitrogen all show the law of first increasing and then decreasing.The removal rates of COD,ammonia nitrogen,nitrate nitrogen,total phosphorus and total nitrogen are 69%,88%,98%,85% and 90% respectively at 35?.According to the electricity generation performance and pollutant removal efficiency of microbial fuel cell,the temperature value of 35?should be selected.(3)In the process of carbon,nitrogen and phosphorus removal by single chamber microbial fuel cell,the pH value,temperature and C/N ratio of the anode solution are controlled unchange,and the nitrogen concentration of the anode solution is changed only.The output voltage increases first and then decreases with the increase of nitrogen concentration.The peak value of the output voltage is 173.83 mV when the nitrogen concentration is 4 mg/L.With the increase of nitrogen concentration,COD,nitrate-nitrogen,total phosphorus and total nitrogen all increase first and then decrease.The maximum removal rates of COD,nitrate,total phosphorus and total nitrogen are 74%,98%,88% and 93% respectively at 4 mg/L nitrogen concentration.Therefore,the nitrogen concentration of 4 mg/L is selected as the appropriate value.(4)In the process of carbon and nitrogen removal and phosphorus removal by single-chamber microbial fuel cell,the pH value,temperature and nitrogen concentration of the anode solution are controlled unchanged,and only the C/N ratio concentration of the anode solution is changed.The output voltage increase first and then decrease with the increase of C/N ratio.The peak value of the output voltage is 158.33 mV when the C/N ratio is 4:1.The removal rates of COD,nitrate nitrogen and total phosphorus are the highest when C/N ratio is 4:1,which are 65%,94% and 82% respectively.The removal rate of total nitrogen increases with the increase of C/N concentration.When the C/N ratio is 16:1,the removal rate of total nitrogen is the highest,which is 90%.Considering comprehensively,the C/N ratio concentration is 4:1 as the suitable C/N ratio concentration in this experiment.