The Effect Of Bioelectrochemistry Systems Combined With Actived Carbon On The Transition Of Sludge Particle And Membrane Fouling Characteristic During Methanol Treatment In AnMBR

Under the background of increasingly tight international fossil energy supply and promotion of ecological civilization construction,how to achieve synchronous industrial wastewater treatment and energy recovery has become a hot issue in this industry.The anaerobic membrane bioreactor（AnMBR）based on traditional anaerobic digestion technology cannot only effectively improve the anaerobic bioconversion of wastewater,but also reduce the loss of highly active microorganisms in reactor through the efficient filtration performance of the membrane module.This further improves the permeate quality and energy conversion efficiency of AnMBR.However,in the treatment process of methanolic wastewater,the long-term stable operation of AnMBR is seriously restricted by membrane fouling problem caused by sludge particle refinement and microbial metabolism.Based on this,this thesis takes methanolic wastewater as an example,and AnMBR as the core technology to explore the influence of bioelectrochemical systems（BES）and granular activated carbon（GAC）on the membrane fouling behaviors and the characteristics of anaerobic sludge particles.The stimulation effect of electrochemical system on methane transformation and metabolism mechanism in anaerobic treatment of methanol wastewater was investigated to provide technical guidance for the promotion of AnMBR technology in the real-world treatment of industrial methanolic wastewater.The main conclusions are as follows:（1）A bioelectrochemical system coupled anaerobic membrane bioreactor（BES-AnMBR）was operated to treat methanol wastewater.This system was run to investigate the effect on anaerobic methane conversion（increased from 76.66%to 79.77%）and membrane fouling control under different voltages.The results show that BES-AnMBR system can improve the methane conversion of methanolic wastewater in AnMBR.With the external voltage applied,the disintegration trend of sludge particles was effectively alleviated.To some extent,the stimulation of weak current could alleviate the sludge particle refining problem in the long-term operation process of methanol wastewater.The microbial analysis showed that Mesotoga accounted for a large proportion of methanogens after the voltage was applied.And the methanotrophic methanogens in the system transformed from methyl methanotrophic methanogens to acetic acid methanotrophic methanogens.This change was the most obvious at the voltage of 0.6 V.Therefore,applying appropriate intensity voltage（0.6 V）can improve the methane conversion efficiency and alleviate the sludge particle refining phenomenon in the long-term operation process.（2）Different dosages of GAC was added into a lab-scale AnMBR to explore the efficiency on anaerobic methane conversion and sludge granulation.The results show that the AnMBR fed with GAC could promote sludge agglomeration.The addition of GAC could drive the metabolic activity of microorganisms and promoted the secretion of EPS,especially the TB-EPS.After adding GAC,the disintegration trend of sludge particles was effectively alleviated.However,adding over dosage of GAC would also hinder the development of microorganisms,secreting much EPS to protect the cells and enlarge the sludge viscosity.The fluidization of GAC also mitigated the formation of cake layer,which aggravated other types of membrane fouling inversely,not conducive to the long-term process stability of AnMBR.Therefore,the addition of 1.0 g/L of GAC can promote the granulation of sludge particles under appropriate（HRT>14 h）,which facilitates the treatment of methanol wastewater in AnMBR.（3）The anaerobic methane conversion and membrane fouling control efficiency of methanol wastewater were explored in a GAC-AnMBR system under different applied voltages.After voltage appiled,AnMBR could maintain steady operation（COD removal rate:94%-96%,p H:6.5-7.11）.The results show that under the same HRT and applied voltage（HRT 14 h,0.8 V）,the CH₄ yield was significantly higher than that of single BES-AnMBR system(increased from 5.39 L CH₄/L_–reactor/d to 7.30 L CH₄/L_–reactor/d).The tolerance of the hybrid system to the applied voltage was also higher than that of BES-AnMBR.At the voltage of 0.2 V,the median particle size of sludge particles increased,which means that applying appropriate voltage can reduce the sludge particle refinement problem in the long-term process of methanolic wastewater.At the voltage of 0.8 V,the TMP rose slowly with the corresponding stable CH₄ yield(7.30 L CH₄/L_–reactor/d),conducive to the stable operation of AnMBR.To sum up,applying appropriate intensity of voltage（0.8 V）can improve the methane conversion efficiency of AnMBR and alleviate the membrane fouling.