Study On The Influence And Optimization Of Dosing GAC On Inverted A~2O-MBR System

Membrane bioreactor(MBR)combines the advantages of wastewater biological treatment technology and membrane separation technology.It has the advantages of small footprint,good treatment effect,and low residual sludge.However,the problem of membrane fouling is always the main constraint for its further application.The subject comparatively explored the impact of granular activated carbon(GAC)dosing on the mixed liquid characteristics and membrane fouling of the inverted A~2O-MBR system,and explored how to optimize the treatment effect and reduce the degree of membrane fouling from the perspective of operation.By analyzing the effects of different operating conditions on system treatment effects and membrane fouling,the effluent flux and the mixed liquid reflux ratio were optimized to provide basis and reference for its application in actual engineering.The main conclusions reached are as follows:(1)Inverted A~2O-MBR system with GAC added has better removal efficiency of COD and ammonia nitrogen than non-added systems,with removal rates increased by0.65%,1.48%,and 0.41%,respectively,all reaching new water quality standard;TMP's change rule shows that the membrane pollution rate of the system is significantly slowed after GAC is added;the EPS results of filter cake layer sludge show that the EPS concentration of filter cake layer sludge is lower,and the membrane pollution is lighter,which is similar to TMP The analysis results are consistent;It shows that adding GAC can improve the treatment effect and membrane fouling degree of the inverted A~2O-MBR system.(2)COD,ammonia nitrogen,and TN treatment effects are better when the flux is10,15,and 20 LMH,respectively.When the flux is 15 LMH,the treatment effect is the best and better than the new water quality standard;TMP The change law shows that as the flux increases,the transmembrane pressure difference cycle time becomes shorter,and the membrane fouling rate increases;the EPS results of the filter cake sludge show that the EPS concentration of the filter cake sludge is the lowest at a flux of 15 LMH At20LMH,the EPS concentration and polysaccharide concentration are both higher.Higher EPS concentration will increase the adhesion of sludge to the membrane.At this time,the membrane pollution is the most serious.The total membrane pollution resistance is the smallest at 15LMH and the flux is 20LMH.The time is the largest,which is consistent with the performance of EPS.Based on the above effluent effects and membrane pollution under different fluxes,15LMH is selected as the optimal effluent flux.(3)When the reflux ratio of the mixed solution is 50%,100%,and 150%respectively,the system has a good treatment effect on COD,ammonia nitrogen and total nitrogen with little difference;the change law of TMP shows that as the reflux ratio of the mixed solution increases,The system's transmembrane pressure difference period becomes shorter and the membrane fouling rate becomes larger.The EPS analysis results show that the EPS concentration of aerobic pond sludge and filter cake sludge increases with the increase of the mixed liquid reflux ratio;the total membrane fouling The resistance Rt is the smallest when the reflux ratio of 100%mixed solution is the largest,and the largest when it is 150%;considering the effluent effect and membrane fouling rate under different reflux ratio conditions,it is determined that 100%is the best mixed solution reflux ratio.