Study On The Extracellular Electron Transfer Dependent Anammox Process And Application

Compared with the traditional biological nitrogen removal process,anammox technology is expected to be applied to nitrogen removal in sewage with low carbon nitrogen ratio because of its significant advantages such as low operating cost and low sludge yield.However,due to the lack of nitrite,slow growth of anammox bacteria and high requirement of culture conditions in actual sewage,the single application of this technology in actual sewage treatment is restricted.In recent years,it has been proved that anaerobic ammox bacteria have the ability of extracellular electron transfer.Therefore,under this premise,this paper combines anaerobic ammox technology with electrochemistry to construct a microbial electrochemical system to achieve nitrogen removal without nitrite.The main research contents and results are as follows:(1)A three-electrode anaerobic ammox reactor was constructed to successfully remove nitrogen through an anaerobic ammox process dependent on extracellular electron transfer,and the maximum nitrogen removal efficiency was 93.2%.Compared with nitrite-driven anammoxidation process,it is difficult to maintain stable nitrogen removal load using only ammonia nitrogen as substrate by applied voltage.In the absence of nitrite,the decrease of Candidatus Brocadia abundance was the main reason for the significant reduction of nitrogen removal load.Candidatus Kuenenia was the dominant bacterial species in the electroactuated anammox process,and both nitrifying bacteria and denitrifying bacteria contributed to the nitrogen removal in this system.(2)The output voltage of microbial fuel cell based on carbon brush air cathode anode is about 0.3 V.A microbial fuel cell coupled electric driven anaerobic ammox process was constructed to simulate the treatment of municipal sewage,with the highest COD removal rate up to 88.94% and total nitrogen removal rate up to 76.80%.Microbial fuel cells can provide stable voltage output to maintain the anaerobic ammox process dependent on extracellular electron transfer.In addition,the three electrode anammox reactor can also provide energy that can be recycled.