The Research On The Performance Of The Treatment Of Saline Wastewater By Constructed Wetlands Combined With Microbial Fuel Cell

The vertical flow constructed wetlands in combination with microbial fuel cells?CW-MFC?was used as the research object in this study,and it studied the generation of biomass electric energy and the removal efficiency of total phosphorus?TP?,total nitrogen?TN?,ammonia nitrogen?NH₄⁺-N?and chemical oxygen demand?COD?in the synthetic wastewater by introducing saline wastewater treatment?ST?and non-saline wastewater treatment?NT?.Based on the analysis and comparison of the relative abundance of microbial community,types of extracellular polymers substance?EPS?and functional microbial groups of the inoculated original sludge and two sets of CW-MFC sludge in anode and cathode,this paper expounds the water purification effect and the conclusion of power generation.Finally,through the cost-benefit analysis model?CBA?,it used the cost-benefit ratio?CBR?to characterize the comprehensive benefit ratio of several CW-MFC systems in wastewater treatment,so as to preliminarily evaluate the social and economic benefits of constructed wetland microbial fuel cell in the treatment of saline wastewater.The results showed that:?1?The removal rate of TP and COD was not significantly inhibited by salinity,but the removal rate of NH4+-N and TN in ST was significantly lower than that of NT?p<0.05?when using the vertical flow constructed wetland microbial fuel cell to treat the saline wastewater.?2?The introduction of salinity directly increased the total ion concentration in wetland environment?the maximum conductivity could reach 9.85 mS/cm?,while also it effectively reduced the internal resistance of the device?140.29?in ST and 415.21?in NT?,and the maximum power output in ST and NT can reach 16.4 mW/m²and 3.9 mW/m²respectively.?3?From the start-up to the stable operation of the device,although the diversity of microorganisms in ST has decreased compared with NT,the proportion of electrochemically active bacteria?EAB??such as Ochrobactrum,etc.?has increased significantly?p<0.05?and EAB was dominant in microbial community gradually.However,compared with ST,the proportion of functional microbiology such as AOB,NOB and DNB in NT increased significantly?p<0.05?.?4?In addition to genes related to lipid metabolism,xenobiotics biodegradation and metabolism,and metabolism of other amino acids,the values of other functional genes in ST were significantly lower than those in NT?p<0.05?.?5?The enzymes related to oxidative respiratory chain were significantly higher in ST than in NT?p<0.05?and the species number of EPS produced by the microorganisms in ST was higher than that of the original inoculated sludge and NT.The enzymes related to the oxidative respiratory chain and EPS?such as aromatic protein,fulvic acid-like,etc.?,which are relatively high in ST,can act as electron transfer shuttle to promote the transfer of electrons and protons in ST.?6?Finally,it used the cost-benefit analysis model for analysis and comparison and the CBR value of CW-MFC constructed in this study is lower than that of other devices with the same electrode area under the situation of practice,so it has better comprehensive economic benefits.