Effect Of Sludge Age On Kinetics Parameters Of SBR/OSA Process

In the 21st century,the rapid development of activated sludge method,at the same time,it costs a lot of money and the sludge treatment with serious secondary pollution has become the focus of water treatment workers.The invention of OSA process has met the desire of water treatment researchers all over the world to solve the surplus sludge problem from the source.Although OSA process can reduce the generation of surplus sludge in the process of water treatment,how to achieve the best effect still needs to be studied step by step.This paper is based on the theory of endogenous respiration and activated sludge model to compare the difference of SBR/OSA process kinetics parameters under different sludge age conditions and demonstrate the relationship between sludge reduction effect and kinetics parameters.In the study of sludge reduction effect,SBR/OSA process was used as the experimental group,and SBR process was used as the control.The effluent water quality of 100 days and residual sludge discharge of 60 days were measured under the condition of 10 and 30 days of sludge age in the stable operation stage of the two processes,to verify whether the sludge reduction effect of SBR/OSA process conforms to the previous conclusions.Then,dynamic parameters of SBR/OSA process at 10 and 30 days of sludge age were measured to verify the conclusion that dynamic parameter bH was the main reason for sludge reduction and explore the influence of dynamic parameters of SBR/OSA process at sludge age.The following conclusions can be drawn by analyzing the experimental results:（1）Under different sludge age conditions,the two processes run stably,and the basic water quality indexes of effluent except total phosphorus all reach grade A standard.Under the condition of 10d and 30d sludge age,the sludge yield of SBR/OSA process was reduced by 22.86%and 19.79%compared with SBR process,respectively.The value of MLVSS/MLSS of the sludge is stable around 0.85,and the sludge index SVI is less than 150,indicating that the inorganic particle content of the sludge is small and the degradation performance is good,which is beneficial to the subsequent determination of kinetic parameters.（2）The kinetic parameters of SBR/OSA processes of different mud ages were determined by respiration method.Under the condition of 10d and 30d mud age,the yield coefficient of heterotrophic bacteria in SBR/OSA system was 0.7945 and 0.8149,respectively,and there was no significant difference between the two groups.The maximum growth rates of heterotrophic bacteria were 4.3432 d-1 and 4.2772 d-1,respectively.The attenuation coefficient bH of 10d mud age is 1.35d-1 and that of 30d mud age is 0.69d-1.It can be considered that YH and μ max have little relation with sludge reduction and are not affected by sludge age,while bH is greatly affected by sludge age,and bH of 10d sludge age is larger than bH of 30d sludge age.（3）Dynamic parameters of SBR/OSA under two mud age conditions were checked by Yobs formula derived from Lawrence-McCarty equation.The difference between the calculated Yobs of 10d mud age and the measured results was 14.09%,and the difference was 29.60%for 30d mud age.It may be that bH of 10d is larger and that of 30d sludge age is smaller,or it may be that the apparent yield coefficient of sludge is smaller.bH after correction still accords with the conclusion that the larger the attenuation coefficient is,the better the sludge reduction effect is.In general,the measured kinetic parameters are more reliable.（4）By comparing the data of the previous researchers,it was found that sludge age had no effect on YH and μ max of SBR/OSA process;Three groups of bH have obvious differences,but 10 d sludge age of bH is greater than 20d sludge age bH and sludge age of 20d reduction effect is better than 10d sludge age,it is not about the attenuation coefficient,the greater the sludge reduction effect is good conclusion,comparison of the experimental data of different research therefore only prove influential to bH sludge age doesn’t prove that the influence related to sludge reduction.Finally,by analyzing and summarizing the research conclusions of other literatures on the kinetic parameters of aerobic bacteria,it is verified that sludge age has little effect on YH and μmax,but has a great effect on bH.