Calcution Of ASM Parameters Y_H,S_S And X_S Based On In-situ Determination Of Carbon Dioxide Concentration

The starch wastewater and the glucose wastewater were used as degrading substrates in this experiment,Through the analysis of the carbon dioxide in-situ determination curve in the process of wastewater degradation by Sequencing Batch Reactor（SBR）,the method for the determination of the heterotrophic bacteria yield coefficient（Y_H）,readily biodegradable material（S_S）and slowly biodegradable material（X_S）was established based on carbon dioxide in-situ determination.This study evaluates the quality of the results of this method from three aspects:carbon recovery rate,precision and accuracy,and explored the effects of aeration flow rate and organics concentration on the measured value of the Y_H,S_S and X_S.The results of the study are as follows:Carbon dioxide in-situ determination of strach wasterwater glucose wastewater has three obvious periods:The first stage is S_S degradation stage,in which the peak value of CO₂ concentration curve of biochemical reaction begins to decrease from aeration reaction to biochemical reaction.The second stage is the X_S degradation stage,which lasts from the peak of the biochemical reaction CO₂ concentration curve to the beginning of the stable stage,and the third stage is the endogenous respiration stage,which lasts from the stable stage of the biochemical reaction CO₂ concentration curve to the end of the reaction.For the same wastewater,the smaller the aeration flow rate,the higer the peak value of biochemical decomposition CO₂ curve,and the higher the matrix concentration,the longer the peak duration of CO₂ concentration curve and the later the end time.The calculation formulas of YH,SS and XS are Y_H=1-（QB）/（?COD·V）、S_S=1/V·Q_s/1-Y_H and X_S=_V¹·1^{Q_s+x-（Q_s）}/1-Y_H respectively by in-situ determination of carbon dioxide concentration.In order to evaluate the quality of In situ determination of carbon dioxide concentration,the carbon budget analysis and the calculation of accuracy and precision of the experimental results were carried out respectively.The results showed that the carbon recovery rates of glucose wastewater and starch wastewater were 96%～104% and 96%～105% respectively during the in-situ carbon dioxide determination experiment;The average value of Y_H is 0.68 mg·mg^-1,which is close to but slightly higher than the recommended value of 0.67 mg·mg^-1 by IAWQ.The accuracy（standard deviation）of Y_H is 0.09.The experiment of the influence of aeration flow on the determination of Y_H,Ss and X_S show that the aeration flow rate and aeration time have a great influence on the results of Y_H determination,and the Y_H value measured at 0.6 L·min^-1 aeration flow rate is significantly lower than that measured at other four higher aeration flow rate.The aeration flow rate also has a great influence on S_S and X_S,for the same wastewater,when the aeration flow rate is small,the concentration of S_S is higher and the concentration of X_S is lower.The experimental results show that:The Y_H of glucose wastewater was 0.91±0.01 mg·mg^-1.The fitting value of S_S concentration to glucose concentration ratio is 0.7045 mg_COD·mg^-1,the fitting degree R² is 0.9959;the fitting value of X_S concentration to glucose concentration ratio is 0.053 mg_COD·mg^-1,and the fitting degree R² is 0.8358.In this study,the in-situ determination curve of CO₂ concentration was correlated with the degradation stages of S_S and X_S in ASM model,which provides a new method for the determination of stoichiometric parameters Y_H and water quality characteristic parameters S_S and X_S in ASM,and promotes the ASM to better serve the design,operation and management of wastewater treatment plants.