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CN-121977966-A - Method for rapidly determining external reflux ratio of sewage plant

CN121977966ACN 121977966 ACN121977966 ACN 121977966ACN-121977966-A

Abstract

The invention provides a method for rapidly determining the external reflux ratio of a sewage plant, which solves the problem that the external reflux ratio is difficult to estimate accurately due to the lack of a flowmeter and difficult maintenance in the prior art. The method comprises the steps of collecting external reflux sludge, continuously sampling three times at a reflux pump outlet pipeline sampling point or a secondary sedimentation tank sludge reflux channel, taking the sludge as a sample to be tested after mixing uniformly, collecting anaerobic tank sludge, selecting three points along the length direction of the tank, and taking the sludge as the sample to be tested after mixing by adopting a multipoint mixing sampling method. The concentration was determined gravimetrically. And obtaining the external reflux ratio based on a calculation method deduced by a material balance principle. The method does not need additional purchasing equipment, relies on conventional laboratory equipment, takes no more than four hours for single-group testing, is suitable for the sewage plant of the A2O process and the derivative process thereof, has the advantages of high efficiency, economy, strong universality and accurate result, and can provide reliable basis for process regulation of the sewage plant.

Inventors

  • CHEN YANLIN
  • LI CHENG
  • JIAO YANG
  • ZHANG JUN
  • PENG MENGWEN
  • WANG FEI

Assignees

  • 中国长江三峡集团有限公司
  • 长江生态环保集团有限公司

Dates

Publication Date
20260505
Application Date
20260123

Claims (10)

  1. 1. The method for rapidly determining the external reflux ratio of the sewage plant is characterized by comprising the following steps of: a) Collecting an external reflux sludge sample and an anaerobic tank sludge sample; b) Respectively measuring the concentration of the external reflux sludge sample And the concentration S of the anaerobic tank sludge sample; c) Based on the principle of material balance, according to the formula: Calculating an external reflux ratio R; In the formula, The unit of the sludge concentration in the anaerobic zone is mg/L; the concentration of the returned sludge outside the secondary sedimentation tank is in mg/L.
  2. 2. The method for rapidly determining the external reflux ratio of the sewage plant according to claim 1, wherein in the step a), the external reflux sludge sample is collected by continuously taking 3 samples of 500mL each time at a reflux pump outlet pipeline sampling point or a secondary sedimentation tank sludge reflux canal, and uniformly mixing the samples to be tested.
  3. 3. The method for rapidly determining the external reflux ratio of the sewage plant according to claim 1, wherein in the step a), the sludge sample in the anaerobic tank is collected by taking 3 points along the length direction of the tank at the position 30-50cm below the liquid level in the middle of the anaerobic tank, and mixing the samples by a multi-point mixing sampling method to obtain the sample to be tested.
  4. 4. The method for rapidly determining an external reflux ratio of a sewage plant according to claim 1, wherein in the step b), the concentration determination is performed by a gravimetric method.
  5. 5. The method for rapidly determining the external reflux ratio of a sewage plant according to claim 4, wherein the specific steps of the gravimetric method comprise: i) Pretreating a filter membrane, namely adopting a glass fiber filter membrane with the thickness of 0.45 mu m, drying the filter membrane for 2 hours at 103-105 ℃ to constant weight, wherein the twice weighing difference is less than or equal to 0.4mg; ii) filtering and washing, namely taking 100-200mL of sample, carrying out suction filtration, and washing the filter membrane with distilled water for 3 times; iii) And (3) drying and weighing, namely placing the filter membrane in a drying oven at 103-105 ℃ for 2 hours, cooling the filter membrane in a dryer for 30 minutes, weighing, repeating the operation until the weight is constant, and calculating a concentration value.
  6. 6. The method for rapidly determining an external reflux ratio of a sewage plant according to claim 5, wherein in the step ii), the amount of the sample to be taken is adjusted according to the concentration of the sludge so that the mass of the trapped solid is 10-100mg.
  7. 7. The method for rapidly determining the external reflux ratio of a sewage plant according to claim 1, wherein the sewage plant adopts an A2O process or a derivative process thereof.
  8. 8. The method for rapidly determining an external reflux ratio of a sewage plant according to claim 1, wherein the formula is as follows Material balance formula for sludge concentration in anaerobic tank From the finishing derivation, wherein The unit of the water inflow rate is m 3 /h.
  9. 9. The method for rapidly determining an external reflux ratio of a sewage plant according to claim 8, wherein the external reflux sludge concentration is as follows Sludge concentration in anaerobic zone Satisfy the following requirements ≥1000mg/L。
  10. 10. The method for rapidly determining an external reflux ratio of a sewage plant according to claim 8, wherein the inflow rate is as follows The deviation between the value range of the real-time inflow or daily average inflow of the sewage plant and the designed treatment flow of the biological treatment unit of the sewage plant is less than or equal to +/-10 percent.

Description

Method for rapidly determining external reflux ratio of sewage plant Technical Field The invention relates to the technical field of municipal sewage treatment, in particular to a method for rapidly determining the external reflux ratio of a sewage plant. Background In the operation management of municipal sewage treatment plants, the external reflux ratio of sludge is a key parameter for regulating and controlling the sludge concentration and sludge age of a biological treatment unit and realizing the aim of denitrification and dephosphorization. However, the existing external reflux ratio acquisition mode has the obvious defects that on one hand, a special online flowmeter is not installed in a sludge reflux pipeline of many sewage treatment plants due to design omission, cost control and the like, and a non-metering pump for conveying reflux sludge cannot provide accurate flow data, and on the other hand, a sludge reflux medium contains high-concentration suspended solids, so that scaling, blockage or abrasion of a flowmeter sensor is easily caused, inaccurate metering, difficult maintenance and high cost are caused. The above problems cause difficulty in quick and accurate acquisition of external reflux ratio by operation and maintenance personnel, and influence on accurate regulation and control of sewage treatment process, so that a practical and efficient alternative determination method is needed. Disclosure of Invention The invention aims to solve the problems of equipment deficiency, difficult maintenance, inaccurate measurement and the like in the prior art when an external reflux ratio is measured by a flow meter, and provides a rapid measuring method which is simple and convenient to operate, low in cost and high in applicability. In order to achieve the above purpose, the present invention adopts the following technical scheme: A method for rapidly determining the external reflux ratio of a sewage plant comprises the following steps: Sample collection: Continuously taking 3 times of samples at a sampling point of a reflux pump outlet pipeline or a sludge reflux channel of a secondary sedimentation tank, taking 500mL of samples each time, uniformly mixing the samples to be tested, and avoiding concentration deviation caused by sludge sedimentation; And 3 points are taken from the position 30-50cm below the liquid level in the middle of the anaerobic tank along the length direction of the anaerobic tank, and the sludge sample is mixed by adopting a multipoint mixing sampling method to be used as a sample to be detected, so that the sample representativeness is ensured. Concentration measurement: Respectively measuring the concentration of the external reflux sludge by adopting a weight method And anaerobic tank sludge concentration。 The method comprises the following specific steps: pretreating a filter membrane, namely adopting a glass fiber filter membrane with the thickness of 0.45 mu m, drying the filter membrane for 2 hours at 103-105 ℃ to constant weight, wherein the twice weighing difference is less than or equal to 0.4mg; Filtering and washing, namely taking 100-200mL of sample, carrying out suction filtration, adjusting the sample taking amount according to the sludge concentration to ensure that the trapped solid mass is 10-100mg, washing the filter membrane with distilled water for 3 times, and removing soluble impurities; And (3) drying and weighing, namely placing the filter membrane in a drying oven at 103-105 ℃ for 2 hours, cooling the filter membrane in a dryer for 30 minutes, weighing, repeating the operation until the weight is constant, and calculating a concentration value (unit: mg/L). And (3) calculating an external reflux ratio: Based on the principle of material balance, according to the formula Calculating the external reflux ratioThe formula is a sludge concentration material balance formula of an anaerobic tankFrom the finishing derivation, whereinThe unit is m3/h for the inflow water flow of the sewage plant. The difference between the concentration S 1 of the external reflux sludge and the concentration S of the anaerobic zone is more than or equal to 1000mg/L during calculation, the effectiveness of a calculation result is ensured, the real-time water inflow or daily uniform water inflow of the sewage plant is selected as the water inflow Q, and the deviation of the value of the water inflow Q and the design treatment flow of the biological treatment unit of the sewage plant is less than or equal to +/-10%. The method is suitable for the sewage treatment plant adopting an A2O (anaerobic-anoxic-aerobic) process or a derivative process thereof, and can be widely adapted to the working conditions of different equipment configurations and sludge properties. Working principle: In a sewage treatment plant adopting an A2O process or a derivative process thereof, sludge separated by the secondary sedimentation tank flows back to the anaerobic tank through an external reflux