The Electricity Generation And Pollutant Removal From Landfill Leachate By Using Microbial Fuel Cells(MFCs)

Sanitary landfill and waste incineration are the main disposal methods of garbage harmlessness in our country.The high concentrations of organic waste water generated during the landfill and dumping process of landfill leachate is characterized by complex water quality and varied compositions.It is the most difficult wastewater to be treated in the world.if handled improperly,it will pose a serious threat to human health and the environment.Landfill leachate contains large amounts of energy,ammonia nitrogen(NH3-N)and other resources.Recycling of these resources can improve the sustainability of leachate treatment.However,the existing treatment methods have high cost,high energy consumption,risk of secondary pollution and development investment The new technology of less recycling resources in waste water is the challenge of the future development of landfill leachate treatment.Microbial fuel cell(MFC),as a new type of wastewater treatment technology,can simultaneously remove pollutants such as organic matter,ammonia nitrogen,phosphorus and metal and generate energy to recover energy.In this paper,the MFC technology for landfill leachate treatment has the problems of low electricity production,poor stability and poor water quality of MFC alone,so as to optimize the structure and operating mode of the reactor and improve the electricity generation and pollutant removal performance of the landfill leachate by MFC,Stable treatment effect,and MFC technology combined with electrochemical oxidation method to optimize the electrolysis reaction conditions,improve water quality.Aiming at the problem of low electric power produced by MFC in landfill leachate,the influence of structural factors such as reactor electrode spacing and anode-anode area ratio on the performance of landfill leachate treated by MFC was studied.The results showed that the output voltage of waste water with low electrodeposition volume fraction treated by small electrode spacing reactor was high,the removal rate of NH3-N was up to 99%,the performance of large electrode spacing reactor was little influenced by the change of water quality,High COD and COD removal rates were above 82%.COD removal rate of different electrode spacing reactors was proportional to volume.COD removal rates of leachate stock solutions with 2cm,4cm and 6cm electrode spacing were 1.9g/d,4.1 g/d,6.2 g/d.The cathode reactors operating with low leachate volume fraction wastewater reactors produce electricity performance and pollutant removal performance better than unilateral cathode reactors,but the performance of bilateral cathode reactors affected by water quality,the operation of high-leachate filtrate volume fraction of wastewater When electricity is low,the pollutant removal rate is low.Aiming at the problem of instability of MFC wastewater containing high concentration of organic compounds,two kinds of MFC combination systems were proposed based on the characteristics of different structured reactors in wastewater treatment:four reactors with 2cm electrode separation and hydrostatic series system and 6cm electrode separation 2cm reactor and electrode distance Hydraulic series combined MFC system.The combined system processes leachate more than a single MFC,and the effluent pollutant concentration is effectively reduced and the electricity production performance is improved.The COD and NH3-N removal efficiencies of the combined system were 97.3%and 91.2%,respectively.However,the performance of reactors operating at high pollutant concentration was gradually aggravated.The COD and NH3-N removal rates of the combined system were 93.5%?52.6%.The reactor with electrode spacing of 6cm could run the leachate liquid continuously and steadily.The COD removal rate exceeded 92%and the output voltage was 287mV.Compared with the latter,the latter utilizes the advantages of different electrode spacing reactors for wastewater treatment,high power generation and stable pollutant treatment.Aiming at the problem of leachate containing a large amount of bio-refractory organic matter and the MFC leachate effluent quality is not ideal,the electrochemical effluent treatment of MFC is advanced to further improve the water quality.The electrode with high oxygen evolution potential is used to optimize the electrolysis conditions The removal of pollutants,considering a variety of factors,the Ti/SnO2-Sb-Ni electrode as the anode,the current density of 20mA/cm2,adding chloride ion concentration of 2.5g/L for the optimal reaction conditions,electrolysis 8h effluent COD,NH3-N total removal rates were 99%,100%.Energy analysis shows that MFC combination system can recover 2.79 kWh/m3 of energy from leachate,providing a new idea for efficient treatment of leachate.