| With the shortage of water resources and low sewage treatment rate in country,Microbial fuel cell(MFC)-Constructed wetland(CW) systems has been used as a sewagetreatment technology with simultaneous electricity energy recovery from pollutantchemical energy in sewage.MFC-CW system was filled with three kinds of diameter of activated carbonparticles in anode with bio-cathode. Studying sewage treatment efficiency and capacityelectrical properties under five HRT, optimizing two HRT for domestic wastewatertreatment. Running MFC-CW and CW system with the same conditions under this twoHRT to examine the biological treatment and electricity production. Studyed MFC-CWand CW systems under12h, developed the distribution of organic pollutants andtransformation rules in the system in water DOM(Dissolved Organic Matter).The performance of sewage treatment and electricity generation has beeninvestigated with different hydraulic retention time (HRT). The results showed that withthe extension of HRT, the COD and NH4+-N removal efficiency increased initial anddecreased gradually, but the SS removal efficiency increased gradually. when HRT was12h, the removal efficiency of COD and NH4+-N achieved the highest,89.2%and36.0%respectively; SS removal efficiency was93.2%.The internal resistance of thesystem showed a gradually increasing trend with the extension of HRT, when HRT was6h, the system obtained a stable output voltage was0.68V, the minimum resistance andmaximum power density was46.2and1.30W/m3, respectively. The maximumcolumbic efficiency achieved7.96%when HRT was48h. The dissolved oxygen (DO)of cathodic chamber decreased from7.3mg/L to2.0mg/L after stopping aeration for12h,and the output voltage decreased by0.002V accordingly. Furthermore, the outputvoltage decreased by0.009V when stop aeration for24h.Results about MFC-CW and CW system showed that: PH value of water indifferent stroma of MFC-CW system were slightly smaller than the CW system,smaller PH value obtained under longer HRT (48h). when HRT was12h, MFC-CWsystem COD removal efficiency reached83.1%, CW system was74.6%. Bio-electricityproduction contributed to CW degradation of COD in wastewater. When HRT was12hMFC-CW system TN removal rate was16.6%, the removal rate reached8.3%whenHRT was48h. MFC-CW system NH4+-N removal rates were4.5%,3.4%and2.0%atdifferent layers when HRT was48h.Results of DOM showed that with the deepening of the two systems DOC removalwas improved. Biological effects can contribute to CW system HPI, HPO-A and HPO-Ndegradation; while HPO-N and TPI-N can be completely degraded.UV-254removalefficiency of MFC-CW system(74.2%) was better than CW system(69.9%). Further analysis showed that biological electricity production promoted hydrophilic(HPI)protein degradation and the degradation of TPI-A protein for CW system was better thanMFC-CW system. The removal of polysaccharides for MFC-CW system was better thanCW system. MFC-CW system had a better treatment effect not only for cellularmetabolites degradation also for fulvic acids which CW system could not degrade andhumic substances showed a accumulation trend in MFC-CW systems. |
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