| As a novel wastewater treatment technology,microbial electrochemical technology(MET)has been widely investigated by many researches because it has represented various advantages on higher efficient organic degradation,lower energy consumption,energy recovery,lower sludge production.While,in a typical microbial electrochemical system(MES),a cation exchange membrane often utilized as a separator,which lead to a higher cost and limit its application and promotion.At the same time,the cation exchange membrane will block the continuity on hydraulic between MES chambers,which make it more complex on system structure,the reason is that it will be necessary to set a flow around method to accomplish continuity on hydraulic when used to application.Besides,the law of nutrient removal and energy output is still unclear when using the practice wastewater as the substrate,the structure of MES needs more optimization to promote the pollutants removal rate and energy output efficiency.To solve above problems,and push the MES into application,to develop MES equipment for small scale decentralized sewage treatment in villages and towns This research will be studied following these aspects.In this study,a biocathode microbial electrolysis system based on dynamic biofilm separator theory was constructed,which also compared with traditional cation exchange membrane system on power output characteristics and pollutants removal rate.The results indicates that,the dynamic membrane MES obtained bigger output current density 5.99±0.11A/m3,which improved by 43% than cation exchange membrane MES.It can limit the directly diffusion of COD and DO when the dynamic biofilm separator presented.The anode chamber solution can directly enter the cathode chamber without flowing around,which ensure the internal hydraulic continuity.The results indicate that the porous separator material can not only solve the problem of high costs on cation exchange membrane but also the internal mass transfer and diffusion.In MES,it consists of various of processes,including aerobic metabolism,anaerobic metabolism and microbial electrochemical process,it is very important to understand the mass transfer and energy balance characteristics among this combined system.This research investigates the pollutants removal and energy dissipation characteristics under maximum power density(Pmax),maximum current density(Imax),open circuit(OC)conditions respectively.The results showed that pollutants removal rate can be significantly improved under closed circuit,the COD in effluent was lower than 50mg/L(A level).There was no obvious difference between Pmax and Imax conditions,while the energy removal efficiency can up to 90±2% under Imax condition.This research also suggests the internal theory of lower observered sludge yield,which may because of current presented in MES accelerate the decomposition on the electrode,which is also an advantage in MES.To further improve the dynamic biofilm separator MES performance on pollutants removal efficacy and output energy,this study discussed the impact of different electrode stack mode and showed that it has the highest power output 721±25m W/m3 when the number of anode and cathode ratio was 1:2,while these MES represents similar pollutants removal efficiency.Appropriate evaluation method was proposed for the selection of porous separator materials.Through evaluating the COD?DO mass transfer coefficient and charge transfer resistance of specific middle materials combined with corresponding power density,when the COD and DO mass transfer coefficient and charge transfer resistance were 1.78×10-3cm/s,0.85×10-3 cm/s,and 6.784?,this porous material can satisfy the requirement.In this research,it also indicates the key factors on long term sustainable operation,proposing and verifying the operating strategy.“Cycled no substrate and anaerobic” is one of the effective strategies to maintain the stability of MES pollutants removal efficiency and power output performance. |
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