Study On Domestic Wastewater Treatment Technology And Energy Recovery Based On Anaerobic Membrane Bioreactor

Aerobic biological treatment has played a very important role in the treatment of urban domestic sewage and the improvement of urban water environment in China.While the conventional aerobic biological treatment is an energy-intensive activity and will produce a large amount of excess sludge.Not only potential available energy in wastewater has been ignored,but also the excess sludge will caused environmental pollution.With the development of the idea of wastewater treatment and resourcing,people start to reclaim wastewater treatment to build predicated energy utilization technology of wastewater.Although the treatment of wastewater with traditional anaerobic biological reactor can achieve good treating effect,such problems as loss of sludge,low energy recovery rate and sensitive to temperature still exist.An effective measure to avoid above problems is that to combine anaerobic bioreactor and membrane bioreactor together.Concerning the problems above,an labe-scale anaerobic membrane bioreactor（AnMBR）was built to conduct this research with the simulated domestic sewage as research object.The treatment effect,biogas production and membrane fouling characteristic of AnMBR was investigated by changing organic loading rate and hydraulic retention time during operation period.Furthermore,comprehensive environmental performance evaluation of AnMBR was also conducted.During the operation period with HRT from 8 to 15 h,OLR from 0.77 to 1.82 kg COD/m³?d,high removal of COD and stable operation state of AnMBR was observed at 35℃.The research results showed that AnMBR has a certain degree of impact load capacity.The COD concentration of effluent is lower than 100mg/L,which meets the standard of pollutants for municipal wastewater treatment plant and irrigation in farmland.With the improvement of OLR,the methane production showed a linear trend,which the linear equation is CH₄（g）=356.16×OLR+182.34.The dissolved methane yield percentage of the total methane yield was 36.72%.The membrane has a certain effect on the pollution in the water,which plays an important role in the stabilization of the anaerobic membrane bioreactor.AnMBR in the hydrolysis fermentation stage occupies the dominant position,and the methanogenic stage accounted for a small proportion of the microbial biochemical process.The results of membrane fouling characteristic research showed that the total resistance and TMP of the membrane was influenced effluent flux.Protein was more likely to cause membrane fouling than polysaccharide.The sludge concentration and sludge viscosity could reflect the degree of membrane fouling to a certain extent.The cake layer of membrane was helpful to improve the effluent quality of AnMBR.AnMBR membrane fouling was mainly controlled by cake layer,which its linear equation is.The inherent resistance of AnMBR was higher,but the membrane fouling rate K was relatively slow,which showed that the shear force produced by the stirring paddle in the reactor can produce better water conservancy conditions and reduce the process of membrane fouling.The main energy consumption of AnMBR during operation period is 0.23kW?h/m³,which came from the mechanical equipment.An MBR has a great energy potential cause of no need to aeration and no excess sludge production.During the production stage of AnMBR wastewater treatment plant,the highest environment load is global warming which was mainly derived from dissolved methane.And the AnMBR WTTP may lead to eutrophication because of the effluent containing a large amount of nitrogen,phosphorus.The effect of global warming and eutrophication can’t be ignored during the production stage of AnMBR wastewater treatment plant and the highest environment load is global warming.The carbon emissions of AnMBR WTTP was mainly derived from dissolved methane,which can further reduce the energy consumption and achieve the goal of energy saving and emission reduction by taking some measures to maximize methane in the water.The AnMBR WTTP may lead to eutrophication because of the effluent containing a large amount of nitrogen,phosphorus,which can be used to irrigate farmland to avoid nutrients directly into the natural water and reduce the consumption of synthetic fertilizer.The maximum collection of methane and utilization of nutrients in the effluent can reduce the impact of AnMBR WTTP on the environment.