Study On Aerobic Flat-sheet Membrane Bioreactor For Coal Gasification Wastewater Treatment

The aim of the present study was to find out the optimal operational mode and parameters of coal gasification wastewater treatment with aerobic flat-sheet membrane bioreactor?MBR?.And make the feasible methods to alleviate membrane fouling depending on the studies on membrane fouling.On the basis of initiation and operation of MBR,the conclusion were listed as follows:During the startup stage,the average volume of the influent load was1².27 kg COD/?m³·d?,the average sludge load was 0.17⁰.42 kg COD/?kg MLSS·d?,the MLSS concentration continues to grow,COD and ammonia removal had a good effect.The average removal rates were81.66%,71.66%,respectively.SV₃₀0 stabled at 30%⁵0%,SVI value stabled at 60¹00 mL/g,sludge had a good cohesion and settling properties.During the stable operation stage,maintained the MLSS concentration of 4000⁵500 mg/L and DO concentration of 3.5⁵.0 mg/L,influent COD concentration of 350¹000 mg/L,NH₄⁺-N of 25⁶0 mg/L,total phenols concentration of 23²60 mg/L.Continuous operation at different HRT?48 h,32 h,16 h,12 h,10 h?,the study of the impact of HRT on treatment effect.COD removal efficiency reached the highest in HRT of 16 h,with average removal rate of 91.97%;NH₄⁺-N removal in HRT 32 h was the best,with average removal rate of 91.13%;total phenols in HRT 12 h was the best,with average removal of 91.27%.Also studied the impact of influent water quality of on effluent COD concentration.The result indicated that the system had good anti-load capacity.Membrane fouling was intensified with the decreased of HRT.TMP was rapidly rising,exceed the maximum 0.055 MPa.Determined the best operating HRT was 16 h due to the effect of water treatment and membrane fouling.Through the study and analysis of membrane fouling and factors.Combined with the system operation,summarized mitigation measures against membrane fouling.Including aeration intensity,MLSS concentration,membrane pumping method,operating HRT and intermittent pumping water?pumping stops ratio 10 min:2min?.Finally,a small pilot study of membrane fouling cleaning agents was carried out.Selected alkaline and acid cleaning agents.Compared the membrane recovery rate,0.5%HCl was selected to be the best cleaning agent.Overall,the experiment had obtained better treatment effect.COD?NH₄⁺-N and total phenols average removal rate was 85.39%,91.13%,89.17%,respectively.The highest effluent concentration of COD,NH₄⁺-N and total phenols was 189 mg/L,7.89 mg/L,35.28 mg/L,respectively.The advanced treatment was needed to meet emission standards.