Efficiency And Mechanism Of 2-bromoethanesulfonate And Lysozyme In Microbial Fuel Cell To Enhance Sludge Degradation And Electricity Generation

The number and scale of sewage treatment plant in China are increasing year by year.The excess sludge is a by-product of the sewage treatment process,and its production is also increasing.The treatment and disposal of excess sludge has become an urgent environmental problem.In microbial fuel cell(MFC),the electricigens attached to the surface of the anode can convert the biomass energy in the substrate into electrical energy to achieve sludge degradation and electricity generation simultaneously.In order to enhance the power generation and the degradation of excess sludge,the substrate additives were optimized among 2-bromoethanesulfonate(BES),sophorolipid and lysozyme,and the effect of the amount of them on the performance of MFC was discussed.In order to study the effect of additives in MFC,50 mmol/L of BES,0.1 g/g TS of sophorolipid and 0.1 g/g TS of lysozyme were added to the excess sludge in the anode champer respectively.At the same time a blank control group and a glucose control group were set up.The results show that in terms of power generation performance,after adding BES,the startup time was 15 days and the maximum full battery voltage was 0.80 V.The startup time is 42.3% shorter and the full battery voltage is 23.1% higher than that of the blank control group.Adding sophorolipid and lysozyme can only shorten the start-up time but cannot enhance the power generation of the system.In terms of organic matter removal,sophorolipid and lysozyme can improve the removal rate of TCOD.After adding lysozyme,the removal rate of TCOD was the highest(78.6%).The addition of BES had no significant effect on the removal rate of TCOD,but the coulomb efficiency was the highest(0.26%).In order to study the effect of additives' dosage on MFC,BES and lysozyme were selected as the additives.The dosage of BES was 150 mmol/L and 250 mmol/L and the dosage of lysozyme was 0.3 g/g TS and 0.5 g/g TS.The results showed that when the dosage of BES was 250 mmol/L,the voltage was the highest(0.70 V),which was slightly higher than that of the blank control group(0.65V).When the dosage of BES was 150 mmol/L,the voltage during the operation process had no significant change compared with the blank control group,but the internal resistance(118 ?)was the lowest and the maximum power density(3.35 W/m3)was the highest.When dosing with the lysozyme,it failed to enhance the power generation of the system and the internal resistance of the system increased.When the dosage increased,the removal rate of TCOD also increased.When the dosage of lysozyme was 0.5 g/g TS,the TCOD removal rate was 79.1%.The addition of BES had no obvious effect on the removal of TCOD.Microbiological mechanism analysis showed that the addition of BES had an influence on the microbial community structure of the anode biofilm.Proteobacteria associated with electricity generation had the highest abundance,which was conducive to electricity generation.The abundance of other bacterial groups such as Chloroflexi,Bacteroidetes,Actinobacteria,Firmicutes,etc.were slightly increased,which can promote the degradation of organic matter and electricity generation.The addition of lysozyme had a great influence on the microbial community structure,and Firmicutes was the dominant bacterial group in the anode biofilm.And BES inhibited the methanogenesis of microorganisms.At the functional genes level,the addition of BES and lysozyme had only a minor effect on a small number of functional genes.The twocomponent system may have an important influence on the power generation process.Environmental information processing related genes were the dominant functional gene group in the power generation process.Adding BES can increase the abundance of related genes,which was conducive to electricity generation.The study showed that adding a certain amount of BES to the sludge in the anode chamber can enhance the power generation of MFC,and adding a certain amount of lysozyme can enhance the degradation of sludge.This method provided new ideas and methods for enhancing the power generation and excess sludge degradation of MFC.