Variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal

Abstract

The variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal is intended to solve the problem that the existing sewage treatment plant operating cost accounting cannot truly reflect the pollutant reduction cost, especially the existing accounting method ignores the impact of water quality changes on costs; the present invention counts the actual operating power consumption, chemical dosage, pollutant inlet and outlet concentrations and reduction load of the sewage treatment plant; determines the graded simulation threshold value based on the data distribution, and establishes a simulation curve of the response relationship between the pollutant reduction load and power consumption and chemical dosage under different thresholds; constructs a variable cost accounting model covering operating power consumption and chemical dosage; and then uses the model to calculate the actual variable cost; by selecting key indicators and establishing a mathematical accounting model, cost accounting with pollutant reduction level as the core is realized, which improves the scientificity, accuracy and practicality of the accounting, provides new ideas and method support for the cost accounting of urban sewage treatment systems, and has replicability and scalability.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a sewage treatment variable cost accounting method based on the evaluation of pollutant removal energy and material consumption. Background Art

[0002] The operating cost of a sewage treatment plant is a key factor affecting its operating efficiency, and it is also an important factor in determining whether energy conservation and emission reduction measures can be effectively implemented. During the operation of a sewage treatment plant, most of the energy consumption and material consumption are concentrated in the sewage treatment link, and these inputs are closely linked to production costs. Generally speaking, sewage treatment costs can be divided into two categories: fixed costs and variable costs. Fixed costs mainly involve the initial investment in the sewage treatment plant and labor costs, etc. These costs are relatively fixed and will not fluctuate significantly with changes in the treatment process. Variable costs are mainly caused by changes in factors such as the amount of water treated and water quality, including electricity costs, pharmaceutical costs, and tap water costs.

[0003] For sewage treatment plants that have been built and put into operation, their fixed costs are mainly related to the design parameters and the choice of process routes. Once determined, their investment is relatively stable. However, variable costs are closely related to the amount and quality of water treated. When the amount of water treated increases, the concentration of influent pollutants increases, or the requirements for effluent water quality become more stringent, the pollutant reduction load will increase accordingly. In order to meet higher treatment requirements, sewage treatment plants need to extend the hydraulic retention time and optimize the process flow, which will inevitably lead to an increase in the amount of electricity required for the operation of the treatment equipment and the amount of reagents added, which in turn changes the variable costs of operation.

[0004] At present, the charging standards for sewage treatment service fees in most cities in my country are mainly calculated based on the "sewage treatment volume". However, the input cost per unit of treated water is closely related to factors such as the design scale of the sewage treatment plant, the influent concentration, and the effluent water quality requirements. Therefore, using only the sewage treatment volume as the basis for determining the operating cost of the sewage treatment plant cannot truly reflect the cost of reducing pollutants. This practice not only affects the fair trading of sewage discharge rights, but also fails to effectively motivate sewage treatment companies to improve treatment efficiency and reduce more pollutants.

[0005] In addition, there is a significant problem with the existing cost accounting methods, namely, the lack of accurate calculation methods and billing models for the variable costs of sewage treatment plants. Since variable costs are closely related to the actual operating conditions of sewage treatment, a more refined accounting method is needed to accurately reflect their changes. However, in the existing domestic technical system, a complete and universal method and model for calculating the variable costs of sewage treatment plants has not yet been formed.

[0006] In summary, the existing cost accounting methods for sewage treatment plants have many shortcomings and are in urgent need of improvement and perfection. In order to solve these problems, the present invention proposes a variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal. This method aims to overcome the defects of the cost accounting method based on the amount of sewage treatment, and by constructing a cost accounting model related to the pollutant reduction load, it can more realistically reflect the operating costs of sewage treatment plants and provide a more scientific, accurate and practical method support for the cost accounting of urban sewage treatment systems. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal, so as to solve the problem of inaccurate cost accounting in the field of sewage treatment, especially the technical difficulty that the existing technology only determines the operating cost of the sewage treatment plant based on the sewage treatment volume, which cannot truly reflect the limitations of pollutant reduction costs.

[0008] In order to solve the above technical problems, the technical solution adopted by the present invention is a method for calculating the variable cost of sewage treatment based on the energy and material consumption of pollutant removal, which comprises the following steps: Step 1: Calculate the actual power consumption of the sewage treatment plant, the dosage of the main chemicals, the influent concentration of related pollutants, the effluent quality and the load reduction; Step 2: Combine the numerical distribution differences of the sewage treatment plant's influent concentration, effluent water quality and pollutant reduction load, and determine the hierarchical simulation threshold according to the change nodes of the data distribution; Step 3: According to the graded simulation threshold, establish the response relationship simulation curves of influent concentration, effluent quality, pollutant reduction load, sewage treatment equipment operation power consumption, and agent dosage under different threshold conditions; Step 4: Select the simulation relationship based on the operation data of the sewage treatment plant during the evaluation period, and build a variable cost accounting model for the sewage treatment plant that covers the operation power consumption and the dosage of the reagents; Step 5: Use the cost accounting model to calculate the actual variable cost of the sewage treatment plant during the evaluation period.

[0009] In the preferred solution, the statistical calculation in Step 1 specifically includes: Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , electricity consumption of sewage treatment equipment , effective carbon source dosage , Effective phosphorus removal agent dosage , Effective dehydration agent dosage The statistical accounting data are all daily average values ​​of the sewage treatment plant. The statistical time range should cover at least one natural year and should be the actual operating data of the previous natural year of the evaluation period.

[0010] In the preferred solution, the pollutant reduction load calculation formula in Step 1 is as follows: (1) (2) (3) (4) In the formula, the amount of water treated for sewage treatment plants; , , , , , , , Represents water inlet Concentration, water concentration, inlet ammonia nitrogen concentration, outlet ammonia nitrogen concentration, inlet Concentration, water Concentration, water inlet Concentration, water concentration.

[0011] In the preferred solution, the specific steps of Step 2 are to calculate the daily average of the twelve months of the year. Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration The data is cumulatively distributed and statistics are taken, and the classification simulation threshold is determined according to the change nodes of the data distribution.

[0012] In the preferred scheme, when the cumulative distribution statistics of the daily average data of the sewage treatment plant for the twelve months of the year are performed in Step 2, the change nodes of the data distribution are considered to determine the graded simulation threshold, thereby reflecting the actual distribution of the inlet concentration, effluent water quality and pollutant reduction load.

[0013] In the preferred solution, the specific steps in Step 3 include: Load reduction , Ammonia nitrogen reduction load The hierarchical simulation threshold is established to establish the power consumption of sewage treatment equipment Model fitting relationship; According to the carbon-nitrogen ratio The threshold of graded simulation is established to establish the effective carbon source dosage Model fitting relationship; according to the water concentration The threshold of graded simulation is established to establish the dosage of effective phosphorus removal agent. The fitting relationship of Load reduction The threshold of the graded simulation is established to establish the effective dehydration agent dosage The fitting relationship is obtained, and the model equation with higher correlation is selected as the cost accounting basis for the electricity consumption of sewage treatment equipment and the dosage of effective reagents.

[0014] In the preferred solution, the equation with higher correlation is selected in Step 3. , , , It serves as the cost accounting basis for the electricity consumption of sewage treatment equipment and the amount of effective reagents added to ensure the accuracy of cost accounting.

[0015] In the preferred solution, in Step 4, according to the evaluation period of the sewage treatment plant Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration Select the simulation relationship under different classification threshold conditions and combine them to form the cost accounting model as follows: (5) In the formula, For variable costs, For electricity cost, For the cost of the drug; , , , They are unit electricity cost, carbon source agent price, phosphorus removal agent price, and dehydration agent price; To calculate the number of days, ; , They are , the weight coefficient of the impact of ammonia nitrogen reduction load on power consumption; For different water concentration conditions, and Representative correspondence Conditional Load reduction Power consumption Quantization equation between; For different influent ammonia nitrogen ratio conditions, and Representative correspondence Ammonia nitrogen ratio under the condition Carbon source dosage Quantization equation between; For different effluent ammonia nitrogen concentration conditions, and Representative correspondence Ammonia nitrogen reduction load under conditions Power consumption Quantization equation between; For different water concentration conditions, and Respectively represent the corresponding Water outlet under conditions concentration Phosphorus removal Quantization equation between; For different water concentration conditions, and Respectively represent the corresponding Conditional Load reduction Dosage of sludge dewatering agent The quantization equation between .

[0016] In the preferred scheme, the cost accounting model in Step 4 includes unit electricity charges, carbon source agent prices, phosphorus removal agent prices, dehydration agent prices, and quantitative equations and weight coefficients obtained according to the response relationship simulation equation. The weight coefficient is determined according to the correlation coefficient of the selected response relationship simulation equation. The larger the correlation coefficient, the larger the corresponding weight coefficient, so as to reflect the different effects of different pollutant reduction loads on electricity consumption and agent dosage.

[0017] In the preferred scheme, the time range of the sewage treatment plant operation data in Step 1 should at least cover the data of twelve months of the previous year, and the model fitting of Step 2 and Step 3 and the actual cost accounting of Step 4 should be carried out in time after the sewage treatment plant data is updated to ensure the timeliness and accuracy of the cost accounting.

[0018] The variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal provided by the present invention has the following beneficial effects: 1. The present invention solves the problem of inaccurate cost accounting in the field of sewage treatment, especially the problem that the existing technology only determines the operating cost of the sewage treatment plant based on the sewage treatment volume, which cannot truly reflect the limitations of pollutant reduction costs; 2. The present invention realizes the refined accounting of sewage treatment costs through the steps of statistical accounting data, determining the classification simulation threshold, establishing the response relationship simulation curve, etc.; 3. The present invention proposes that when a sewage treatment plant encounters equipment updates, process adjustments, etc., the variable cost model should be updated in a timely manner to ensure the accuracy and practicality of the model; 4. The method proposed in this invention is based on the energy and material consumption of pollutant removal, that is, the reduction load of pollutants. Compared with the traditional sewage treatment cost accounting which is mainly based on the sewage treatment volume, it more truly reflects the cost of pollutant reduction, improves the fair transaction of sewage discharge rights and the motivation of sewage treatment enterprises to improve treatment efficiency; 5. The present invention solves the problem of large calculation errors caused by differences in process scale effects and operation and management modes of different sewage treatment plants; 6. The method of the present invention can truly reflect the pollutant reduction cost of the sewage treatment plant during operation, and provide guidance and method support for the cost accounting of the urban sewage treatment system; 7. The present invention uses actual operation data to construct a cost accounting model, and regularly updates the model algorithm according to equipment and process conditions to avoid accounting errors and ensure the scientificity, accuracy and practicality of the accounting model; 8. The method of the present invention is a universal accounting method, which can be used to calculate variable costs for sewage treatment plants with different operating modes. It has certain replicability and scalability, and provides support for the establishment of a pay-per-performance mechanism for improving the quality and efficiency of urban sewage. 9. The present invention has strong scalability and compatibility, and can also realize automation and real-time monitoring of sewage treatment cost accounting by expanding the intelligent management system, thereby improving management efficiency and promoting sustainable development and cost optimization of the sewage treatment industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 It is a technical flow chart of the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments: Example 1 like Figure 1 As shown, a variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal is provided, comprising the following steps: Step 1: Calculate the actual power consumption of the sewage treatment plant, the dosage of the main chemicals, the influent concentration of related pollutants, the effluent quality and the load reduction; Step 2: Combine the numerical distribution differences of the sewage treatment plant's influent concentration, effluent water quality and pollutant reduction load, and determine the hierarchical simulation threshold according to the change nodes of the data distribution; Step 3: According to the graded simulation threshold, establish the response relationship simulation curves of influent concentration, effluent quality, pollutant reduction load, sewage treatment equipment operation power consumption, and agent dosage under different threshold conditions; Step 4: Select the simulation relationship based on the operation data of the sewage treatment plant during the evaluation period, and build a variable cost accounting model for the sewage treatment plant that covers the operation power consumption and the dosage of the reagents; Step 5: Use the cost accounting model to calculate the actual variable cost of the sewage treatment plant during the evaluation period.

[0021] In this embodiment, the statistical calculation in Step 1 specifically includes: Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , electricity consumption of sewage treatment equipment , effective carbon source dosage , Effective phosphorus removal agent dosage , Effective dehydration agent dosage The statistical accounting data are all daily average values ​​of the sewage treatment plant. The statistical time range should cover at least one natural year and should be the actual operating data of the previous natural year of the evaluation period.

[0022] Furthermore, the calculation formula for pollutant reduction load in Step 1 is as follows: (1) (2) (3) (4) In the formula, the amount of water treated for sewage treatment plants; , , , , , , , Represents water inlet Concentration, water concentration, inlet ammonia nitrogen concentration, outlet ammonia nitrogen concentration, inlet Concentration, water Concentration, water inlet Concentration, water concentration.

[0023] Furthermore, the specific steps of Step 2 are to calculate the daily average of the twelve months of the year. Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration The data is cumulatively distributed and statistics are taken, and the classification simulation threshold is determined according to the change nodes of the data distribution.

[0024] Furthermore, when the cumulative distribution statistics of the daily average data of the sewage treatment plant for the twelve months of the year are performed in Step 2, the change nodes of the data distribution are considered to determine the graded simulation threshold, thereby reflecting the actual distribution of the inlet concentration, effluent water quality and pollutant reduction load.

[0025] Furthermore, the specific steps in Step 3 include: Load reduction , Ammonia nitrogen reduction load The hierarchical simulation threshold is established to establish the power consumption of sewage treatment equipment Model fitting relationship; According to the carbon-nitrogen ratio The threshold of graded simulation is established to establish the effective carbon source dosage Model fitting relationship; according to the water concentration The threshold of graded simulation is established to establish the dosage of effective phosphorus removal agent. The fitting relationship of Load reduction The threshold of the graded simulation is established to establish the effective dehydration agent dosage The fitting relationship is obtained, and the model equation with higher correlation is selected as the cost accounting basis for the electricity consumption of sewage treatment equipment and the dosage of effective reagents.

[0026] Furthermore, in Step 3, the equation with higher correlation is selected. , , , It serves as the cost accounting basis for the electricity consumption of sewage treatment equipment and the amount of effective reagents added to ensure the accuracy of cost accounting.

[0027] Furthermore, in Step 4, according to the evaluation period of the sewage treatment plant Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration Select the simulation relationship under different classification threshold conditions and combine them to form the cost accounting model as follows: (5) In the formula, For variable costs, For electricity cost, For the cost of the drug; , , , They are unit electricity cost (yuan / KWh), carbon source agent price (yuan / kg), phosphorus removal agent price (yuan / kg), and dehydration agent price (yuan / kg); To calculate the number of days, ; , They are , the weight coefficient of the impact of ammonia nitrogen reduction load on power consumption; For different water concentration conditions, and Representative correspondence Conditional Load reduction Power consumption Quantization equation between; For different influent ammonia nitrogen ratio conditions, and Representative correspondence Ammonia nitrogen ratio under the condition Carbon source dosage Quantization equation between; For different effluent ammonia nitrogen concentration conditions, and Representative correspondence Ammonia nitrogen reduction load under conditions Power consumption Quantization equation between; For different water concentration conditions, and Respectively represent the corresponding Water outlet under conditions concentration Phosphorus removal Quantization equation between; For different water concentration conditions, and Respectively represent the corresponding Conditional Load reduction Dosage of sludge dewatering agent The quantization equation between .

[0028] Furthermore, the cost accounting model in Step 4 includes unit electricity charges, carbon source agent prices, phosphorus removal agent prices, dehydration agent prices, and quantitative equations and weight coefficients obtained according to the response relationship simulation equation. The weight coefficient is determined according to the correlation coefficient of the selected response relationship simulation equation. The larger the correlation coefficient, the larger the corresponding weight coefficient, so as to reflect the different effects of different pollutant reduction loads on electricity consumption and agent dosage.

[0029] Furthermore, the time range of the sewage treatment plant operation data in Step 1 should at least cover the data of twelve months in the previous year of the accounting year, and the model fitting of Step 2 and Step 3 and the actual cost accounting of Step 4 should be carried out in a timely manner after the sewage treatment plant data is updated to ensure the timeliness and accuracy of the cost accounting.

[0030] Example 2 In another preferred embodiment, based on the above embodiment 1, Figure 1 As shown in the figure, a variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal is implemented as follows: 1. Step 2 classification simulation threshold is determined according to the water quality and quantity of the main influent and effluent of the sewage treatment plant. Generally, there should be no less than 2 sections of classification data, such as effluent The relationship curve can be established and the calculation equation can be determined by grading according to greater than or equal to 0.2 mg / L and less than 0.2 mg / L; 2. The correlation coefficients of the simulation equations of the response relationships between the inlet and outlet water quality of the sewage treatment plant selected in Step 3 and the operating power consumption and reagent dosage should all be greater than 0.5; 3. Step 4 Weight coefficient in variable cost accounting model , Determined by the correlation coefficient of the selected response relationship simulation equation, where , the larger the correlation coefficient, the larger the corresponding weight coefficient; 4. Step 4 The unit price of electricity, carbon source agent price, phosphorus removal agent price, and dehydration agent price corresponding to urban sewage treatment plants in different regions can be determined according to the actual level. , , , ; 5. If urban sewage treatment plants encounter equipment updates, process adjustments, etc., the variable cost model should be updated in a timely manner.

[0031] Example 3 In another preferred embodiment, based on the above embodiments 1 and 2, as Figure 1As shown in the figure, statistical accounting is performed on the historical data of a certain year of a certain urban sewage treatment plant, and a model relationship is established with 2023 as the historical data to evaluate the energy consumption and material consumption cost investment in 2024, which should include the following steps: 1. Pass the average daily water intake in 2023 Concentration, water concentration, inlet ammonia nitrogen concentration, outlet ammonia nitrogen concentration, inlet Concentration, water Concentration, water inlet Concentration, water Concentration statistics for sewage treatment plants Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water output also needs to be counted concentration And the electricity consumption of sewage treatment equipment on the corresponding day , effective carbon source dosage , Effective phosphorus removal agent dosage , Effective dehydration agent dosage data; 2. Date of establishment of sewage treatment plant Load reduction , Ammonia nitrogen reduction load , Load reduction , water discharge concentration , effluent carbon-nitrogen ratio The distribution curve of the data, find the change nodes of the data distribution and determine the threshold of the classification simulation; The distribution range is 2~5 tons / day, 5~10 tons / day, 10~15 tons / day. It can be greater than or equal to 0.2 mg / L and less than 0.2 mg / L; 3. Establish the corresponding relationship simulation curves under different simulation threshold conditions respectively. Load reduction , Ammonia nitrogen reduction load The hierarchical simulation thresholds are established to respectively correspond to the power consumption of sewage treatment equipment. The fitting relationship; According to the carbon-nitrogen ratio The hierarchical simulation thresholds are established respectively with the effective carbon source dosage Model fitting relationship; according to the water concentration The threshold values ​​of the graded simulation are used to establish the dosage of effective phosphorus removal agents. The fitting relationship of Load reduction The threshold of the graded simulation is established to establish the effective dehydration agent dosage The above fitting relationship includes but is not limited to exponential relationship, linear relationship and logarithmic relationship. The equation with higher correlation is selected. , , , As the cost accounting basis for the electricity consumption of sewage treatment equipment and the dosage of effective reagents; Establish respectively as The distribution range is 2~5 tons / day, 5~10 tons / day, 10~15 tons / day and the corresponding sewage treatment equipment power consumption The fitting relationship, According to the above, the dosage of effective phosphorus removal agent should be established according to 0.2mg / L or more and less than 0.2mg / L respectively. The fitting relationship is finally formed, and the energy and material consumption accounting equations under different threshold conditions of each parameter are finally formed; 4. Taking 2024 as the evaluation period, determine the annual average Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration , select a simulation relationship corresponding to the hierarchical simulation threshold, and construct a cost accounting model formed by the combination in Step 4 of Example 1; 5. Calculate the energy and material consumption costs of the sewage treatment plant.

[0032] Example 4 In order to more thoroughly illustrate the variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal proposed by the present invention, a specific example will be described in detail below: 1. Data collection and preprocessing First, we selected a municipal sewage treatment plant that has been in operation for many years in a certain area as the specific implementation object; the sewage treatment plant is designed to treat 100,000 tons of sewage per day and adopts the activated sludge treatment process; to ensure the accuracy and representativeness of the data, we collected and counted the operation data of the sewage treatment plant for one year, including the actual daily operation power consumption, the dosage of the main reagents (such as carbon source reagents, phosphorus removal reagents, dehydration reagents), and the influent concentration ( , ammonia nitrogen, , etc.), effluent water quality and pollutant reduction load and other key parameters; all data are counted as daily averages, and the statistical time range is ensured to cover at least one natural year.

[0033] 2. Determination of the threshold value for graded simulation Based on the collected data, the daily average of the 12 months of the year Load reduction , Ammonia nitrogen reduction load , Load reduction , effluent carbon-nitrogen ratio , and water discharge concentration Perform cumulative distribution statistics; determine the threshold of graded simulation by analyzing the change nodes of data distribution; for example, Load reduction , it can be divided into three levels: high, medium and low, each level corresponds to a specific threshold range; similarly, similar grading is performed for other parameters.

[0034] 3. Establishment of response relationship simulation curve Based on the determined hierarchical simulation thresholds, the response relationship simulation curves of influent concentration, effluent quality, pollutant reduction load, sewage treatment equipment operating power consumption, and agent dosage under different threshold conditions are established. The specific approach is as follows: 1) For Load reduction and ammonia nitrogen reduction load , respectively establish their electricity consumption with sewage treatment equipment The model fitting relationship is selected, and the model equation with higher correlation is selected as the basis for cost accounting; 2) For carbon-nitrogen ratio , establish its relationship with effective carbon source dosage The model fitting relationship of 3) For water discharge concentration , establish its dosage with effective phosphorus removal agent The model fitting relationship of 4) For Load reduction , establish its dosage with effective dehydration agent The model fitting relationship.

[0035] When establishing these simulation curves, we used advanced data analysis methods such as nonlinear regression and machine learning to ensure the accuracy and reliability of the model.

[0036] 4. Construction of variable cost accounting model After obtaining the above response relationship simulation curve, we constructed a variable cost accounting model for sewage treatment plants that covers operating power consumption and reagent dosage. The model is as follows: (5) When constructing the model, we determined the weight coefficient based on the correlation coefficient of the selected response relationship simulation equation. The larger the correlation coefficient, the larger the corresponding weight coefficient. At the same time, we also considered actual factors such as the unit price of electricity and chemical prices of urban sewage treatment plants in different regions to ensure the practicality and accuracy of the model. 5. Cost accounting and result analysis Using the constructed variable cost accounting model, we calculated the actual variable cost of the sewage treatment plant for one year; by comparing with the traditional cost accounting method based on sewage treatment volume, we found that the cost accounting method of the present invention can more truly reflect the operating cost of the sewage treatment plant, especially can accurately reflect the impact of pollutant load reduction on cost; in addition, we also found that in different seasons and when the pollutant concentration fluctuates, the model can dynamically adjust the cost accounting, which provides strong support for the operational decisions of the sewage treatment plant and helps to achieve the dual optimization of economic and environmental benefits.

[0037] In the preferred solution, the statistical calculation in Step 1 specifically includes: Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , electricity consumption of sewage treatment equipment , effective carbon source dosage , Effective phosphorus removal agent dosage , Effective dehydration agent dosage The statistical accounting data are all daily average values ​​of the sewage treatment plant. The statistical time range should cover at least one natural year and should be the actual operating data of the previous natural year of the evaluation period. The above settings can comprehensively reflect the operating efficiency and cost investment of the sewage treatment plant in the past year, provide a scientific basis for optimizing the treatment process, adjusting the use of chemicals and energy conservation and emission reduction, and ensure the economy and environmental protection of the sewage treatment process.

[0038] In the preferred solution, the specific steps of Step 2 are to calculate the daily average of the twelve months of the year. Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration The data is cumulatively distributed and statistically analyzed, and the graded simulation threshold is determined according to the change nodes of the data distribution. The above settings can more accurately reflect the changes in key parameters in the water quality treatment process, provide a scientific basis for the subsequent establishment of a graded simulation model, ensure that the model can accurately predict and control under different working conditions, and improve the overall treatment efficiency and stability.

[0039] In the preferred scheme, when the cumulative distribution statistics of the daily average data of the sewage treatment plant for the twelve months of the year are performed in Step 2, the change nodes of the data distribution are considered to determine the graded simulation threshold, so as to reflect the actual distribution of the inlet concentration, effluent water quality and pollutant reduction load; the above settings can more accurately divide the simulation scenarios under different working conditions, optimize the sewage treatment process parameters, improve the treatment efficiency and stability, ensure that the effluent water quality continues to meet the standards, while reducing operating costs, and achieving a win-win situation of environmental and economic benefits.

[0040] In the preferred solution, the specific steps in Step 3 include: Load reduction , Ammonia nitrogen reduction load The hierarchical simulation threshold is established to establish the power consumption of sewage treatment equipment Model fitting relationship; According to the carbon-nitrogen ratio The threshold of graded simulation is established to establish the effective carbon source dosage Model fitting relationship; according to the water concentration The threshold of graded simulation is established to establish the dosage of effective phosphorus removal agent. The fitting relationship of Load reduction The threshold of the graded simulation is established to establish the effective dehydration agent dosage The fitting relationship is established, and the model equation with higher correlation is selected as the cost accounting basis for the electricity consumption of sewage treatment equipment and the effective dosage of reagents; the above settings can accurately predict the energy consumption and reagent consumption under different operating conditions to achieve cost optimization. At the same time, the solution also includes a dynamic adjustment strategy, which automatically adjusts the model parameters according to real-time monitoring data to ensure the dual improvement of sewage treatment efficiency and economic benefits.

[0041] In the preferred solution, the equation with higher correlation is selected in Step 3. , , , It serves as the cost accounting basis for the electricity consumption of sewage treatment equipment and the effective amount of chemical dosage to ensure the accuracy of cost accounting; the above settings can fully reflect the energy consumption and chemical consumption in the sewage treatment process and improve the scientific nature of cost control; at the same time, the plan also includes a mechanism for regular verification of equation parameters to adapt to changes in water quality and ensure the cost-effectiveness of long-term operation.

[0042] In the preferred scheme, the cost accounting model in Step 4 includes unit electricity charges, carbon source agent prices, phosphorus removal agent prices, dehydration agent prices, and quantitative equations and weight coefficients obtained according to the response relationship simulation equation. The weight coefficient is determined according to the correlation coefficient of the selected response relationship simulation equation. The larger the correlation coefficient, the larger the corresponding weight coefficient, so as to reflect the different effects of different pollutant reduction loads on electricity consumption and agent dosage. The above settings ensure the accuracy and rationality of cost accounting. At the same time, the model also takes into account indirect costs such as equipment operation and maintenance costs and labor costs, and obtains the total cost through comprehensive calculation, which provides decision makers with a comprehensive and scientific basis for cost analysis, and helps to achieve dual optimization of environmental protection and economic benefits.

[0043] In the preferred scheme, the time range of the sewage treatment plant operation data in Step 1 should at least cover the data of the twelve months of the previous year, and the model fitting of Step 2 and Step 3 and the actual cost accounting of Step 4 should be carried out in time after the sewage treatment plant data is updated to ensure the timeliness and accuracy of the cost accounting; the above settings can also adjust the data time range according to actual needs. For example, when encountering special weather, equipment failure, etc., the data time length can be appropriately increased to fully reflect the actual operation status of the sewage treatment plant and provide more accurate data support for cost accounting.

[0044] In summary, the variable cost accounting method for sewage treatment based on the energy consumption and material consumption of pollutant removal provided by the present invention solves the problem of inaccurate cost accounting in the field of sewage treatment, especially the problem that the existing technology only determines the operating cost of sewage treatment plants based on the sewage treatment volume, which cannot truly reflect the limitations of pollutant reduction costs; the present invention proposes to use the energy consumption and material consumption of pollutant removal as the evaluation basis for variable cost accounting of sewage treatment, which is completely different from the traditional accounting method based on sewage treatment volume. It takes into account key indicators such as influent concentration, effluent water quality and pollutant reduction load, and is more accurate. It reflects the cost input of sewage treatment in real life; the present invention describes in detail how to determine the graded simulation threshold value based on the numerical distribution differences of the influent concentration, effluent water quality and pollutant reduction load of the sewage treatment plant, and respectively establish the response relationship simulation curves under different threshold conditions. This method is not common in the previous sewage treatment cost accounting, and provides a new perspective and idea for cost accounting; it establishes a variable cost accounting model for sewage treatment plants covering operating power consumption and chemical dosage. The model takes into account multiple factors (such as unit electricity cost, carbon source chemical price, phosphorus removal chemical price, dehydration chemical price, etc.), and is based on Dynamic adjustment is made according to actual conditions, thereby improving the accuracy and practicality of cost accounting. The present invention statistically calculates the actual operating data of the sewage treatment plant (such as power consumption, dosage of reagents and pollutant concentration, etc.), combines the graded simulation threshold and the response relationship simulation curve, and establishes a cost accounting model directly related to the power consumption and dosage of the sewage treatment equipment. This technical innovation has significant application value in the field of sewage treatment. A cost accounting method with pollutant reduction load as the core is proposed, which overcomes the defects of the cost accounting method based on sewage treatment volume. This method can more truly reflect the actual operating cost of the sewage treatment plant and stimulate the motivation of enterprises to improve treatment efficiency and reduce more pollutants. The method of the present invention is not only suitable for variable cost accounting of sewage treatment plants with different operating modes, but also has replicability and promotion. It can provide support for the establishment of a pay-per-performance mechanism for improving the quality and efficiency of urban sewage, and help promote the sustainable development of the sewage treatment industry. At the same time, the method provides data support for the government to formulate a more scientific sewage treatment subsidy policy through refined cost accounting, promotes the deep integration of environmental protection policies and market mechanisms, and lays a solid foundation for achieving a win-win situation of environmental benefits and economic benefits.

Claims

1. A method for calculating the variable cost of sewage treatment based on the evaluation of energy and material consumption of pollutant removal, characterized in that: The method comprises the following steps: Step 1: Calculate the actual power consumption of the sewage treatment plant, the dosage of the main chemicals, the influent concentration of related pollutants, the effluent quality and the load reduction; Step 2: Combine the numerical distribution differences of the sewage treatment plant's influent concentration, effluent water quality and pollutant reduction load, and determine the hierarchical simulation threshold according to the change nodes of the data distribution; Step 3: According to the graded simulation threshold, establish the response relationship simulation curves of influent concentration, effluent quality, pollutant reduction load, sewage treatment equipment operation power consumption, and agent dosage under different threshold conditions; Step 4: Select the simulation relationship based on the operation data of the sewage treatment plant during the evaluation period, and build a variable cost accounting model for the sewage treatment plant that covers the operation power consumption and the dosage of the reagents; Step 5: Use the cost accounting model to calculate the actual variable cost of the sewage treatment plant during the evaluation period.

2. The variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal as described in claim 1 is characterized by: The specific statistical calculation in Step 1 includes Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , Power consumption of sewage treatment equipment , effective carbon source dosage , Effective phosphorus removal agent dosage , Effective dehydration agent dosage The statistical accounting data are all daily average values ​​of the sewage treatment plant. The statistical time range should cover at least one natural year and should be the actual operating data of the previous natural year of the evaluation period.

3. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 2 is characterized in that: The calculation formula for pollutant reduction load in Step 1 is as follows: （1）； （2）； （3）； （4）； In the formula, the amount of water treated for sewage treatment plants; , , , , , , , Represents water inlet Concentration, water concentration, inlet ammonia nitrogen concentration, outlet ammonia nitrogen concentration, inlet Concentration, water Concentration, water inlet Concentration, water concentration.

4. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 3 is characterized by: The specific steps of Step 2 are to calculate the daily average of the twelve months in a year. Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration The data is cumulatively distributed and statistics are taken, and the classification simulation threshold is determined according to the change nodes of the data distribution.

5. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 4 is characterized by: When the cumulative distribution statistics of the daily average data of the sewage treatment plant for the twelve months of the year are performed in Step 2, the change nodes of the data distribution are considered to determine the graded simulation threshold, thereby reflecting the actual distribution of the inlet concentration, effluent water quality and pollutant reduction load.

6. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 5 is characterized by: The specific steps in Step 3 include: Load reduction , Ammonia nitrogen reduction load The hierarchical simulation threshold is established to establish the power consumption of sewage treatment equipment Model fitting relationship; According to the carbon-nitrogen ratio The threshold of graded simulation is established to establish the effective carbon source dosage Model fitting relationship; according to the water concentration The threshold of graded simulation is established to establish the dosage of effective phosphorus removal agent. The fitting relationship of Load reduction The threshold of the graded simulation is established to establish the effective dehydration agent dosage The fitting relationship is obtained, and the model equation with higher correlation is selected as the cost accounting basis for the electricity consumption of sewage treatment equipment and the dosage of effective reagents.

7. The variable cost accounting method for sewage treatment based on the energy and material consumption of pollutant removal according to claim 6 is characterized by: In Step 3, select an equation with higher correlation , , , It serves as the cost accounting basis for the electricity consumption of sewage treatment equipment and the amount of effective reagents added to ensure the accuracy of cost accounting.

8. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 7 is characterized by: In Step 4, according to the evaluation period of the sewage treatment plant Load reduction , Ammonia nitrogen reduction load , Load reduction , carbon-nitrogen ratio , water discharge concentration Select the simulation relationship under different classification threshold conditions and combine them to form the cost accounting model as follows: （5）； In the formula, For variable costs, For electricity cost, For the cost of the drug; , , , They are unit electricity cost, carbon source agent price, phosphorus removal agent price, and dehydration agent price; To calculate the number of days, ; , They are , the weight coefficient of the impact of ammonia nitrogen reduction load on power consumption; For different water concentration conditions, and Representative correspondence Conditional Load reduction Power consumption Quantization equation between; For different influent ammonia nitrogen ratio conditions, and Representative correspondence Ammonia nitrogen ratio under the condition Carbon source dosage Quantization equation between; For different effluent ammonia nitrogen concentration conditions, and Representative correspondence Ammonia nitrogen reduction load under conditions Power consumption Quantization equation between; For different water concentration conditions, and Respectively represent the corresponding Water outlet under conditions concentration Phosphorus removal Quantization equation between; For different water concentration conditions, and Respectively represent the corresponding Conditional Load reduction Dosage of sludge dewatering agent The quantization equation between .

9. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 8 is characterized by: The cost accounting model in Step 4 includes unit electricity charges, carbon source agent prices, phosphorus removal agent prices, dehydration agent prices, and quantitative equations and weight coefficients obtained according to the response relationship simulation equation. The weight coefficient is determined according to the correlation coefficient of the selected response relationship simulation equation. The larger the correlation coefficient, the larger the corresponding weight coefficient, so as to reflect the different effects of different pollutant reduction loads on electricity consumption and agent dosage.

10. The variable cost accounting method for sewage treatment based on the evaluation of energy and material consumption of pollutant removal according to claim 9 is characterized by: The time range of the sewage treatment plant operation data in Step 1 should at least cover the data of twelve months in the previous year of the accounting year, and the model fitting of Step 2 and Step 3 and the actual cost accounting of Step 4 should be carried out in time after the sewage treatment plant data is updated to ensure the timeliness and accuracy of the cost accounting.

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