| Catering wastewater emissions accounted for more and more proportion of city sewage with the development of the catering industry,so the reasonable use has become a new trend.Microbial fuel cell(MFC)is a kind of renewable energy device,which can recycle organic compound containing energy in wasterwater.It also generates electirc energy when degradating organic compound in restaurant wastewate.The third canteen wastewater in a university was regarded as the research object to investigate the water quality characteristics and emission rules,and carried on the pretreated canteen wastewater as influent for continuous flow dual-chamber microbal fuel cell.The influence of the pH value,the dosage of NaCl hydraulic retention time and different cathode electron acceptors were studied on electrical properties and the effect of wastewater treatment in MFC.The third canteen wastewater was detected by instantaneous sampling method,the sampling time was 7:00-9:00,10:30-13:30 and 16:00-19:30,every half hour.The results showed the effluent of the third canteen wastewater was concentralized,partial acid and volatile.In wastewater the average concentration of COD,SS,animal and vegetable oil were 655.79,1920.95,388.012mg/L,respectively.The average concentration of ammonia and TP were 37.66,2.445mg/L,respectively.The experiment used the method of gravity-modified fiber ball filtration to pretreat canteen wastewater.The removal efficiency of COD,SS,animal and vegetable oil were improved with the increase of filter.When the thickness of modified fiber ball was 80cm,the average removal efficiency of COD,SS,animal and vegetable oil could reach 81.86%,10%,87.91%,respectively.The device continuous flow dual-chamber microbal fuel cell was cylinder butt type,the upper part was anode chamber,the lower part was cathode chamber,the middle part was separated by ion exchange membrane.The carbon felt was regarded as the anodic electrode and cathodic electrode,aerated on the cathode with aeration pump.The external circuit resistance was constantly 1000 ?,the temperature in incubator was 35 ?,started the contious flow microbal fuel cell with simulated sewage.The device run stably at the thirty-third day,the voltage could reach 0.34V,the removal rate of COD was about 70%.Then the trial regarded the pretreated canteen wastewater as influent of MFC,the voltage was 0.38V after 10 days.When studying the influence on MFC,the output voltage could reach 0.42V,the removal rate of COD was 73.72%while the pH value was7,the dosage of NaCl was lg/L and hydraulic retention time(HRT)was 24h.Potassium ferricyanide,potassium permanganate,potassium dichromate were respectively regarded as electron acceptors of cathode when other conditions were constant to study the influence of electrical properties and the effect of wastewater treatment on MFC.The results showed that the voltage and the external power density were 0.70V,77mW/m2,respectively,the effluent COD was 125mg/L,the removal rate of COD was 82%while potassium ferricyanide was regarded as electron acceptor of cathode with the concentration of 600mg/L,pH value of 3;The voltage and the external power density were 0.74V,86mW/m2,respectively,the effluent COD was 105mg/L,the removal rate of COD was 85%when potassium permanganate concentration was 300mg/L,pH value was 3;When the concentration of potassium dichromate was 500mg/L,pH value was 3,the output voltage could be as high as 0.85V,the external power density was 113mW/m2,the removal rate of COD was 85?86%,the COD of effluent was 100mg/L.By codtrast,cathodic reduction product MnO2 would increase the resistance of cathode electrode and affect the performance of MFC when potassium permanganate as electron acceptor of cathode;The reduction product Cr(III)could not be ignored for the environmental pollution when potassium dichromate as electron acceptor of cathode;Potassium ferricyanide than oxygen as electron acceptor of cathodec could improve the voltage and power density and no pollution to the environment,it could be widely used in the practical engineering. |
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