| The activated sludge process is the most mainstream treatment method in the current water treatment process,and the respiration rate is the parameter that can directly reflect the activity of the main microorganism in the treatment of the activated sludge system.The microbial activity information reflected by the respiratory rate is unmatched by environmental factors such as pH and temperature,as well as conventional water quality indicators such as COD and ammonia nitrogen.Traditional methods of testing respiratory rate include closed batch methods and continuous aeration methods,but both rely on sampling results of dissolved oxygen meters.This experiment designed a new method for testing the rate of respiration-the differential pressure method,which uses the pressure change formed by microbial respiration in a cavity above a closed can to obtain a real-time respiration rate.The new algorithm was first tested from the perspective of endogenous breathing.When the temperature,MLVSS and OUR is constant,the pressure difference in the algorithm is linearly related to the reaction time.The pressure difference measured in the experiment is also linearly related to the reaction time,which verifies the correctness of the algorithm.Under the longer period of monitoring,the endogenous respiration showed fluctuations,but the endogenous respiration rate measured by the differential pressure method and the traditional closed intermittent method can be consistent in the change trend,and the test results are basically the same.This result indicates that the differential pressure method can replace the closed batch method.The correctness of the new algorithm was then tested from the perspective of total respiratory rate.According to the literature,the specific breathing rate and sludge matrix load ratio follow the Mimen equation when the temperature is constant.In this experiment,the respiration rate data measured by the differential pressure method in half a year was simulated by Matlab at 28?,and the maximum specific respiration rate was 60.98 mgO2/(g MLVSS·h),and the half-saturation rate constant KF is 0.024,and the linear correlation coefficient in the(1/R-l/F)relationship diagram is 0.9654.The correlation is good.This result fully proves that the relationship between the specific breathing rate and the sludge matrix load ratio can well agree with the Mimen equation,and the correctness of the new algorithm is verified again.Finally,the feasibility test of the differential pressure method for measuring the respiratory rate in actual sewage treatment was carried out.The respiratory rate differential pressure curve was analyzed under the conditions of Cr3+ concentration of 40 mg/L and 80 mg/L.By comparison with the blank experimental group,it was found that the higher Cr3+ dosage corresponds to the lower activated sludge respiration rate.In the experiment,the difference in the slope of the pressure difference curve between the two concentrations is obvious,and the judgment can be made in a short time,which has far-reaching significance for the intelligent operation of the sewage treatment plant in the future.In the case of low BOD,by comparing the respiration rate of Prepared nutrient solution and actual domestic sewage,it is concluded that under the same COD,microorganisms have similar respiration rates under Prepared nutrient solution and domestic sewage,which provides a solid theoretical data support for the future development of curve models in laboratory conditions and then extended to field applications. |
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