Research On Microbial Fuel Cells Enhanced Ammonia Nitrogen In Wetland At Low Temperature

The constructed wetland is an ecological sewage treatment with environment-friendly,it is more and more widely used in drinking water source purification,sewage plant tailings treatment and so on.However,the operation of constructed wetland will inevitably be affected by environmental conditions,especially in low temperature conditions,the removal effect of ammonia nitrogen will obviously deteriorate,often less than the expected treatment effect.In this paper,based on the configuration of traditional multi-medium constructed wetland,constructs a Constructed Wetland-Microbial Fuel Cell(CW-MFC),studies the nitrification performance under the condition of low temperature,and discusses the mechanism and feasibility of CW-MFC improving the nitrification performance of constructed wetland in low temperature.The main results are as follows:(1)Using zeolite as the water matrix layer can guarantee the effluent efficiency above 96.7% and up to 77.85% below the zeolite.Microbial nitrification is mainly affected by Deltaproteobacteria and Betaproteobacteria.The addition of microbial fuel cells is conducive to the enrichment of Betaproteobacteria.In addition,the wetland microbial fuel cell device outputs a stable power of 5.93 m W/m3 under the stable removal of ammonia nitrogen.(2)Low temperature will inhibit the efficiency of nitrification in wetlands,and the ammonia nitrogen removal rate of the final effluent of the four wetlands is reduced by 10.51±2.93% from 25℃ discontinuity reduced to 5℃.The efficiency of nitrogen removal before zeolite bed was decreased more obviously,the traditional multi-medium wetland decreased bu 57.57% and the CW-MFC decreased by30.06%-34.17% from 25℃ discontinuity reduced to 5℃.Microbiological analysis showed that the relative abundance of nitrifying bacteria in CW-MFC was higher than that in traditional multi-medium wetlands 8.37%-14.89%,the addition of MFC is beneficial to the enrichment of nitrogenation microorganisms in constricted wetland at low temperature,thus improving the efficiency of nitrogenation at low temperature.(3)During long-term winter operations,plants will death,CW-MFC are more conducive to the removal of ammonia nitrogen,adding separation materials can improve the denitrification efficiency of 7.51%;Separation materials and electrode spacing affect the nitrification of CW-MFC,and when there are separation materials and electrode spacing is 5cm,it is more favorable for ammonia nitrogen removal,and the maximum removal rate of ammonia nitrogen can be increased by 10.25%;The double anode structure can also improve the efficiency of constructed wetlands nitrification to a certain extent.a linear positive correlation between nitrogen removal efficiency and output voltage in CW-MFC.