| In the face of increasingly stringent wastewater discharge standards,the wastewater treatment system is constantly improving its processes,which in turn has higher requirements for the monitoring of wastewater treatment processes.However,the monitoring methods of existing sewage plants are mostly limited to some conventional physical and chemical indicators,which cannot truly and fully reflect the status of sludge,and have poor timeliness.In view of the fact that the sewage treatment system in our country is dominated by activated sludge treatment,this study developed an online monitoring platform for the process characteristics of the activated sludge system to monitor the microbial activity and degradation ability in the activated sludge system in real time.First,the performance of the two dissolved oxygen meters was analyzed through the step response experiment.It was found that the response curves of the dissolved oxygen meter to the step signal are first-order linear systems.The gain constants of the two dissolved oxygen meters during the rising and falling processes were obtained by fitting.And the time constant,which is substituted into the model to obtain the response time of the dissolved oxygen meter.Then,by analyzing the response lag between the two dissolved oxygen meters in the system through the raw water response experiment,the response time of the two dissolved oxygen meters was obtained by the method used to analyze the performance of the dissolved oxygen meter,and the response lag between the two was calculated,and the correction was corrected.By measuring the change in the DO value in the system under endogenous respiration at different flow rates,it can be seen that the change in flow rate has basically no effect on the DO in T2,while the DO in T3 has a downward trend with decreasing flow rate,and the decreasing rate In the future,in order to reduce the interference of the flow rate on the change of DO in the system,the total flow rate of the system with a constant breathing rate was measured in this study.The total flow rate of the system should be around 100-200ml/min by calculation.Discuss the method of measuring the oxygen uptake rate of activated sludge on the online monitoring platform.Measure the actual oxygen uptake rate,endogenous oxygen uptake rate and maximum oxygen uptake rate of activated sludge under the same experimental conditions.Analyze the change trend of various oxygen uptake rate curves and find the actual oxygen uptake rate.The characteristics of the measurement curve are in good agreement with the relationship between the microbial proliferation rate and the substrate concentration described in the Monod equation;the trend of the measurement curve of the endogenous oxygen uptake rate is maintained at a stable value when no matrix and toxic substances are added;the matrix concentration in the raw water when measuring the maximum oxygen uptake rate The ratio of sludge concentration(L)is greater than 0.05.To explore the method of characterizing the nitrification activity of activated sludge with oxygen uptake rate,using ATU as an inhibitor,and the difference between oxygen uptake rate before and after inhibition to represent the nitrification activity.In addition,the relationship between the concentration of NO3--N in activated sludge with time under the same conditions was measured.Straight-line fitting the NO3--N concentration at different times to obtain the production rate of NO3--N.Compare the oxygen consumption to NO3--N under the experimental conditions with the theoretical oxygen consumption to verify the measurement of this monitoring platform.The accuracy of the obtained nitrification activity.Establish a sludge nitrification model on the basis of the original ASM3,refine and delete the components and reaction processes involved in the ASM3 model,focus on the nitrification process,and discuss the ammonia nitrogen oxidation and nitrous nitrogen oxidation separately in the nitrification reaction,and the process of hypoxia reaction is removed.Finally,based on the established sludge nitrification model,the Monod equation is used to describe the expression of microbial growth and matrix degradation,and the relationship between the degradation rate of ammonia nitrogen and the concentration of ammonia nitrogen in the inlet and outlet water and the hydraulic retention time.The calculation formula of the saturation constant and the yield coefficient of the bacteria,the saturation constant and the yield coefficient are calculated.Based on the measured online oxygen uptake rate and kinetic parameters,the nitrogen concentration in the system is estimated,and the application of the monitoring platform in estimating the nitrogen concentration is verified. |
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