| In recent years,the problem of environmental pollution and the energy crisis have become increasingly serious.If waste water treatment can be achieved at the same time,the recovery of resources is no doubt an effective solution to this crisis.The microbial fuel cell(MFC)is a device that simultaneously removes pollutants and generates electrical energy under the action of microorganisms,which is also an advantage compared to the traditional sewage treatment process.However,because MFC involves complex interdisciplinary subjects such as biology and chemical energy,and its research is still in a preliminary stage,its related theories are still immature and need further research to improve.In this dissertation,a dual-chamber MFC denitrification system using activated carbon particles and carbon brushes as electrode materials was chosen as the research object to study the feasibility of this system.Then,based on the completion of the MFC startup,the paper focused on the factors affecting the electricity generation and denitrification of denitrifying MFC.Finally,the feasibility of degradation of pentachlorophenol by MFC was verified,and the scope of MFC pollutant treatment was extended.The main conclusion are as follows:(1)The MFCs composed of activated carbon and carbon brushes were activated in two ways: continuous feed water and intermittent feed water.When the external resistance is 100?,the continuous inlet type is started after 13 d continuous operation,the voltage is stable at about 246 m V,and the intermittent inlet type is stable at about21.3m V after three cycles of operating voltage;The former COD removal load and NO3--N removal load were 1.209 kg/(m3·d)and 44.7 g/(m3·d),respectively,the latter were 1.04 kg/(m3·d)and 38.40 g/(m3·d),respectively.By comparison,it can be found that the continuous feed water start-up is more beneficial to the power generation and decontamination performance of MFC.The scanning electron microscopy(SEM)of the electrode material with stable denitrification MFC showed that a large number of intensive microbial flora appeared on the anode electrode material,mainly rod-shaped bacteria.The presence of microorganisms on the cathode electrode material is relatively loose,which also explains the high removal efficiency of the anode COD and the low removal of the cathode nitrate nitrogen.(2)The increase of nitrate nitrogen concentration in a certain range is beneficial to the denitrification power generation performance of MFC,and beyond thisconcentration range,the performance of MFC will be significantly reduced.When the concentration of nitrate nitrogen was 150mg/L,the power density and current density reached the maximum of 1.83W/m3 and 15.63A/m3,the removal load of nitrate nitrogen reached the maximum value of 61.44g/(m3·d),and the internal resistance dropped to the lowest 53?.(3)With the gradual increase of COD concentration,the power density of MFC continues to increase.When the COD concentration is 450mg/L,the power density reaches a maximum of 1.72W/m3;COD removal efficiency increases first with COD increasing.In the downward trend,when the COD concentration was 400 mg/L,the maximum COD removal load was 1.26 kg/(m3·d).When the COD concentration is250 mg/L,the anode Coulomb efficiency reaches a maximum of 13.9%.(4)The power density of the MFC increases first and then decreases with the increase of the stirring intensity.At a stirring intensity of 150 rpm,the power density reaches a maximum value of 15.01 W/m3,and the internal resistance of the MFC reaches a minimum value of 57 ?.The COD removal load is not greatly affected by the agitation strength and is always maintained at about 1.29 kg/(m3·d).Stirring intensity has a great influence on the removal of nitrate nitrogen in MFC,and it increases first and then decreases with increasing stirring intensity.When the stirring intensity is 150 rpm,the removal load of nitrate nitrogen reaches a maximum of 60.29g/(m3·d).By analyzing the amount of biofilm in the cathode chamber and the SS concentration in the effluent at different agitation strengths,it can be seen that the biofilm content increases first and then decreases with the increase of the agitation intensity,and the SS concentration in the effluent increases continuously as the agitation intensity gradually increases.(5)The removal load and power density of nitrate nitrogen increased first and then decreased with the increase of p H.When the p H of the cathode water was 6.5,the maximum power density was 1.22 W/m3,and the nitrate removal load reached the maximum value.69.12g/(m3·d).The smaller the external resistance,the better the removal of nitrate nitrogen.When the external resistance is 10?,the removal load of nitrate nitrogen is the highest,which is 55.30g/(m3·d).The concentration of nitrite nitrogen in the cathode increases gradually with the increase of external resistance.When the external resistance is 250?,the nitrite nitrogen accumulation concentration reaches the highest value of 0.29 mg/L.The power density gradually decreases with the increase of the external resistance.At 20?,the power density value is the largestat 1.72 W/m3.(6)The MFC with monochlorophenol as the biocathode was activated after 17 days.The concentration of monochlorophenol in the water inlet was set to 30 mg/L,the concentration of the outlet water was 18.4 mg/L,the voltage energy reached 73.56 m V,and the maximum power density was 0.737 W/m3.The internal resistance is161?.When the monochlorophenol influent concentration was 90 mg/L,the MFC generated electricity and the degradation of monochlorophenol reached the optimal value.The voltage reached 102.44 m V and the monochlorophenol removal was 18.61mg/L. |
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