Study On SBR-FO Coupling Process For Domestic Sewage Treatment

The process of rapid urbanization and industrialization has led to an increase in pollution and wastewater.Sewage which untreat or treat substandard may enter the water body.Water pollution may endanger human health,damage the ecological environment,and cause losses to industry and agriculture.Therefore,sewage need to be effectively treated.When a single SBR process is used to treat sewage,the high impact load will inhibit microbial activity and the treatment effect is unsatisfactory.The SBR effluent still contains a certain amount of pollutants.Forward osmosis?FO?,as a low-energy,energy-saving membrane separation technology,widely used in seawater desalination,agricultural fertilizers,wastewater treatment,seawater power generation,food processing and other fields,showing its potential use value.In addition,there will be more serious membrane fouling during the long-term operation of FO process,resulting in decreased membrane water flux,lower water production rate,faster membrane replacement and cleaning frequency,etc.Therefore,it is necessary to delay membrane fouling.This study intends to combine the SBR process and the FO technology to construct a new SBR-FO small-scale test process for the treatment of sewage and wastewater,and to examine the effects of the process on the removal of sewage and wastewater and membrane fouling.Firstly,the sludge from the secondary sedimentation tank of a sewage treatment plant in Guangzhou was used as the inoculum sludge to study the effects of SBR small-scale test process and the characteristics of activated sludge.Then,3.6 wt%NaCl solution was used as the draw liquid,and SBR process water was used as the raw material liquid.The SBR effluent was intensified in the FO mode to investigate the effect of the SBR-FO pilot process effluent.Finally,the membrane fouling of the SBR-FO pilot process was studied and the membrane fouling mechanism was analyzed.The main conclusions are as follows:?1?The concentration of COD,NH₄⁺-N,and TP in the influent water of SBR process was350,35,and 5.3 mg/L,respectively,and the removal efficiency of the effluent was good;the influent COD,NH₄⁺-N,and TP were gradually increased to 950,95,and 12.67mg/L.The concentrations of COD,NH₄⁺-N,TP,NO₂^--N,and NO₃^--N in the effluent were stable at 66,9.8,3.24,1.45,and 9.49 mg/L,respectively,and the effluent effect was not satisfactory.The effect of pollutant removal needs further improvement.?2?The changes of SV,MLSS and SVI indicate that the settled performance of activated sludge after SBR process is stable is good.The change in the SOUR value indicates that the performance of activated sludge is better.Fluorescence spectrum analysis,infrared spectrum analysis and analysis of extracellular polymer components all showed that activated sludge contained a certain amount of polysaccharides and proteins.?3?The SBR-FO process has a significant effect on the removal of wastewater.The removal rates of COD,NH₄⁺-N,and TP are much higher than those of the single SBR process,and the comparison shows that the removal rate of COD,NH₄⁺-N,and TP is relatively high.The removal rate of COD,NH₄⁺-N,and TP is higher by 6.07%,8.35%,and 24.39%than SBR.?4?In the SBR-FO process,unavoidable membrane fouling occurs,especially biological contamination,and the main components of the formed biofilm are bacteria,polysaccharides and proteins.In summary,the SBR-FO process has a significant effect on the removal of domestic sewage,but the long-term operation can not eliminate the occurrence of membrane fouling,which can provide a theoretical basis for the practical application of the SBR-FO process.