Research On Decolorization Of Methyl Orange By Co-substrate Microbial Fuel Cell

In this paper,we aimed to construct a microbial fuel cell(MFC)to achieve the biodegradation of methyl orange in the anode chamber,and to explore the degradation pathways of methyl orange and intermediates in the reaction.The effects of anode operation parameters on the methyl orange decolorization and the electrogenesis were evaluated as well.Based on biocathodes MFC technology,we also evaluated the feasibility of synchronous degradation of nitrate and methyl orange by the co-substrates MFC.The main conclusions are as follows:The new dual-chamber co-substrate MFC utilize the mixture of methyl orange and glucose as fuel.Compared with the traditional biological degradation,the decolorization rate of methyl orange can be as high as 96.38%,and the output voltage reached 0.51 V.With Liquid Chromatograph Mass Spectrometer(LC-MS)detection of the degradation liquid,we found the main intermediate products were found to be the amino benzene sulfonic acid and N,N-dimethyl-p-Phenylenediamine.The decolorization of methyl orange and the efficiency of electricity production of the co-substrate MFC were influenced by the several key parameters of the anode,including the concentration of methyl orange,the concentration of mixture substrate,anode liquid PH,external resistance,temperature,and suspended sludge.Low concentration(100-300 mg/L)of methyl orange have little effect on the output voltage of MFC,indicating that microbial tolerance exists in a certain degree of low concentration of methyl orange;When the initial concentration of methyl orange was300 mg/L,the optimum substrate concentration for the decolorization of methyl orange and microbial growth was 500 mg/L.The pH of anode liquid can influence the decolorization performance by affecting the microbial activity.When the pH was 6.80,the microorganism showed a strongest metabolism,and thus the MFC showed a best decolorization performance.The decolorization rate at 12 h was more than 90% and the removal rate of chemical oxygen demand(COD)reached 57.25%;the external low resistance will accelerate the electron transfer,and decolorization rate of methyl Orange and the removal rate of COD can achieve a higher level;high temperature has some obvious effects on the decolorization and electricity production performance of the MFC system.When the operating temperature was 35 ?,it showed the best electricity production and decolorization performance;The decolorization of methyl orange byco-substrate MFC was mainly relying on the metabolism of the microorganism adhered on anode surface,while a certain amount of suspended sludge will not only increase the output voltage,but also improve the removal rate of methyl orange decolorization and COD removal efficiency.When the performance of nonbiocathode MFC was stable,the 50 mmol/L potassium ferricyanide in cathode was replaced by 50 mmol/L nitrate to construct a biocathode co-substrate MFC.The MFC worked well and following results can be concluded: when the concentration of cathode nitrate was 50 mg/L,the average denitrification rate can reach 2.015 mg/(L?d),the highest output voltage was 0.3 V,the decolorization rate of methyl Orange can reach 72.36% and the removal rate of COD was 43.24% after48h-reaction.The new nonbiocathode MFC can degrade methyl orange efficiently and can be reformed into the co-substrate biocathode MFC,in which the pollution can be synchronously degradated both in cathode chamber and anode chamber.With the advantage of no pollution production,wide application range,and high efficiency,MFC can be a promising tool for azo dyes wastewater treatment.