Study On Kinetic Parameters Of Endogenous Respiration In SBR/OSA Sludge Reduction Process

With the continuous development of sewage treatment technology,how to deal with a large number of surplus sludge becomes the new research hotspot,OSA(Oxic-Settling-Anaerobic)as a kind of has a huge application prospect of sludge reduction technology has been widely concerned.In this paper,SBR and OSA processes are combined into SBR/OSA process,and the sludge reduction effect,kinetic parameters,aeration process and endogenous respiration process of SBR/OSA process are analyzed to explore the sludge reduction mechanism of SBR/OSA process.In this study,SBR process was used as the control group and SBR/OSA process as the experimental group.The effluent quality and residual sludge discharge of the two processes in 180 days of stable operation were investigated,and the sludge reduction effect of SBR/OSA process was analyzed.Based on the theory of endogenous respiration,the differences between the kinetic parameters of the SBR and SBR/OSA processes and the differences in the endogenous respiration process were analyzed,and the oxygen utilization in the aeration process of the two processes was combined to explore the reasons for the sludge reduction in the SBR/OSA process.Research indicates:(1)The overall operation of SBR and SBR/OSA process was stable,and the effluent quality basically reached the A in first grade standard.The sludge apparent yield of the SBR process in the control group was 0.202gMLSS/gCOD,and the sludge apparent yield of the SBR/OSA process in the experimental group was 0.1324gMLSS/gCOD.The sludge reduction of the experimental group compared to the control group was 34.46%.This shows that the SBR/OSA process can achieve sludge reduction without affecting the effluent quality.(2)Respirometry measurements have shown that there is no significant difference between the heterotrophic bacteria yield coefficient YH and the maximum specific growth rate ?max in the SBR and SBR/OSA processes at 25?.However,the sludge attenuation coefficient bH of the SBR/OSA process is 20%higher than that of the SBR process.Further measurement found that at 15?,the sludge attenuation coefficient bH of SBR/OSA process increased by 40%compared with that of SBR process,so it can be determined that the larger attenuation coefficient of SBR/OSA process is the main reason for sludge reduction.(3)Under the same feed composition and operating parameters of SBR and SBR/OSA.processes,the use of oxygen by heterotrophic and autotrophic bacteria is significantly different during aeration.Compared with the SBR process,the SBR/OSA process reduced the proportion of oxygen used by heterotrophic bacteria and increased the proportion of oxygen used by autotrophic bacteria.This indicates that the anaerobic sludge backflow of the SBR/OSA process may cause the ratio of heterotrophic bacteria to autotrophic bacteria in the reactor to change,causing the proportion of heterotrophic bacteria to decrease and the proportion of autotrophic bacteria to increase.(4)The activated sludge of SBR and SBR/OSA process enter the endogenous respiration time,but the entire endogenous respiration phase of the SBR/OSA process lasts longer,and the non-recoverable part of the heterotrophic and autotrophic bacteria in the endogenous respiration phase is more.This indicates that more microorganisms have died at this stage in the SBR/OSA process,resulting in a larger sludge attenuation coefficient in the SBR/OSA process.(5)Heterotrophic and autotrophic bacteria in SBR and SBR/OSA activated sludge enter the endogenous respiration time,but in the absence of substrates,heterotrophic bacteria can use autotrophic bacteria to attenuate the dead part to maintain their own life activities,the recoverable part of heterotrophic bacteria is larger than the autotrophic bacteria,which indicates that the heterotrophic bacteria have stronger anti-hunger ability than the autotrophic bacteria.(6)The conclusion of aeration process was verified by the endogenous respiration process characterized by respiration ratio in SBR and SBR/OSA.In the SBR/OSA process,the proportion of microorganisms in the activated sludge was changed due to the anaerobic sludge reflux,which caused the proportion of heterotrophic bacteria to decrease and the proportion of autotrophic bacteria to increase.This shows that SBR/OSA process activated sludge contains a lager proportion of autotrophic bacteria,and autotrophic bacteria are more vulnerable to decay in the absence of substrates,resulting in the SBR/OSA process sludge decay is more severe.In this study,through in-depth study of kinetic parameters,aeration process and endogenous respiration process in SBR and SBR/OSA process,it was found that SBR/OSA process sludge reduction phenomenon was caused by the change of activated sludge species ratio and the larger attenuation coefficient.