A method for optimizing operation of a sewage treatment plant considering sewage reuse

Abstract

The application discloses a sewage treatment plant optimal operation method considering sewage reuse, comprising the following steps: 1) obtaining basic parameters of the sewage treatment plant; 2) modeling equipment units of the sewage treatment plant according to the basic parameters of the sewage treatment plant to obtain sewage treatment plant equipment unit models; 3) establishing a sewage treatment plant optimal operation model considering sewage reuse according to the sewage treatment plant equipment unit models; and 4) solving the sewage treatment plant optimal operation model considering sewage reuse to obtain a sewage treatment plant optimal operation scheme. The application fully excavates flexibility of the sewage treatment plant, can make loads stable and carry out peak clipping and valley filling, and improves economic efficiency and load stability.

Description

Technical Field

[0001] This invention relates to the field of optimized operation of multi-energy systems, specifically a method for optimizing the operation of wastewater treatment plants that considers wastewater reuse. Background Technology

[0002] Currently, with the acceleration of urbanization and the continuous improvement of research on water-energy relationships, wastewater treatment has become a key area of ​​research in renewable energy utilization. Within water systems, wastewater treatment plants are energy-intensive facilities with high operating costs, consuming 3%-4% of the US power grid load.

[0003] In water-scarce and arid regions, effective water reuse can significantly conserve water, energy, and land. These areas face water resource pressures due to irregular water supply throughout the year. Recycling nutrients and water from urban wastewater into agriculture is key to effectively building a water-energy-food-climate network.

[0004] Current research on wastewater treatment plant management mainly focuses on optimizing wastewater quality to ensure public health and compliance with hygiene and environmental regulations. Most research on energy conservation in wastewater treatment plants remains focused on process optimization. As for wastewater reuse, it mainly focuses on recovering the thermal and chemical energy contained in wastewater. A small number of studies only explore the reuse options for wastewater without considering the impact of reuse on the energy consumption behavior of wastewater treatment plants. Summary of the Invention

[0005] The purpose of this invention is to provide a method for optimizing the operation of a wastewater treatment plant that considers wastewater reuse, comprising the following steps;

[0006] 1) Obtain the basic parameters of the wastewater treatment plant;

[0007] Furthermore, the basic parameters of the wastewater treatment plant include time-of-use electricity purchase price, time-of-use electricity sales price, gas price, wastewater load, irrigation water load, irrigation water price, secondary discharge revenue, tertiary discharge revenue, industrial miscellaneous water load, and industrial miscellaneous water price.

[0008] 2) Based on the basic parameters of the wastewater treatment plant, model the equipment units of the wastewater treatment plant to obtain the equipment unit model of the wastewater treatment plant;

[0009] Furthermore, the wastewater treatment plant equipment unit model includes a treatment unit model, a sludge-to-biogas production model, a CHP unit model, and an energy storage device model.

[0010] Furthermore, the treatment unit model includes a primary wastewater treatment unit model, a secondary wastewater treatment unit model, and an advanced wastewater treatment model;

[0011] The model for the primary wastewater treatment unit is shown below:

[0012] P t,clar =γ s Q t H t / 1000η (1)

[0013] H t =aQ t 2 +bQ t r+cr 2 (2)

[0014] In the formula, the subscript t indicates time t; P t,clar Let be the power of the cleaning pump at time t; η be the efficiency of the cleaning pump; Q t γ is the wastewater flow velocity entering the equalization tank at time t; s Specific gravity of wastewater; H t Let t be the head of the cleaning pump; r be the relative speed of the cleaning pump; and a, b, and c be empirical coefficients for the pump head curve.

[0015] The model of a secondary wastewater treatment unit is shown below:

[0016]

[0017] In the formula, P t,Aer R is the blower power at time t; R is the air gas constant; T in η is the inlet temperature of the fan; B P represents the mechanical efficiency of the blower. a Atmospheric pressure; P t,stat P is the static pressure at the outlet of the blower diffuser. t,dyn For dynamic pressure; Q t,air M is the air mass flow rate; air The molecular mass of air;

[0018] Among them, dynamic pressure P t,dyn Air mass flow rate Q t,air They are shown below:

[0019] P t,dyn =(Q t,air / A dif ) 2 k p (4)

[0020]

[0021] In the formula, A dif The diffuser cross-sectional area; coefficient k p =275N s 2 / m 4 ;K LaThis is the standard oxygen transfer efficiency. This refers to the mass of oxygen per unit mass of air. Standard oxygen transfer rate;

[0022] Standard oxygen transfer rate As shown below:

[0023]

[0024] m t,BOD =Q t,2 (BOD t,in -BOD t,out ConB (7)

[0025] m t,TKN =Q t,2 (TKN t,in -TKN t,out ConN (8)

[0026] In the formula, m t,BOD and m t,TKN The oxygen demand for oxidation and nitrification in the aeration tank are represented by β; β is the mass of oxygen per unit mass of air; C T and C T 0 At temperature T and reference temperature T, respectively. 0 Oxygen saturation concentration in freshwater; C d α is the dissolved oxygen concentration; α is the oxygen transfer ratio in the wastewater; θ is a constant; BOD t,in and BOD t,out The BOD concentration of the influent and effluent of the wastewater treatment plant; TKN t,in and TKN t,out TKN concentration in the influent and effluent of the wastewater treatment plant; ConN is the oxygen ratio required for TKN oxidation; ConB is the oxygen ratio required for BOD oxidation; Q t,2 The flow rate for secondary treatment wastewater;

[0027] The advanced wastewater treatment model is shown below:

[0028] P t,3 =η3V t,3 (9)

[0029] In the formula, η3 is the volume coefficient of wastewater treated per unit of electrical energy in the tertiary treatment stage; V t,3 P represents the volume of water entering the clear water tank after three stages of treatment at time t. t,3 The power consumption of the third-level processing at time t.

[0030] Furthermore, the sludge-to-biogas model includes equations for calculating biogas production, equations for calculating heat loss from the digester wall, and equations for calculating the heat energy required for heating the sludge.

[0031] The equation for calculating biogas production is shown below:

[0032]

[0033] In the formula, the subscript t indicates time t; m sl,t Let β be the sludge mass at time t; wsl p represents the sludge coefficient after wastewater has settled and settled. t,BG Let be the amount of biogas produced at time t; Reference temperature T 0 The sludge biogas production coefficient under the specified conditions; f t (T dig T represents the fermentation temperature T in the biogas digester at time t. dig Biogas production rate; f t (T 0 ρ represents the biogas production rate of the biogas digester at a reference temperature T0 at time t; wsl The average density of the wastewater after it has been left to stand and settle.

[0034] Among them, the gas production rate f t (T dig ) and fermentation temperature T dig The relationship is as follows:

[0035] f t (T dig )=m(T dig -T0) 2 +n (11)

[0036] In the formula, m and n are the coefficients in the quadratic expression;

[0037] The equations for calculating heat loss from the digester wall and the equations for calculating the heat energy required for sludge heating are as follows:

[0038] Heat loss H from the digester wall t,loss The heat energy required for heating sludge (H) t,sludge for:

[0039]

[0040] In the formula, H t,loss H t,sludge These represent the heat loss from the digester wall and the heat energy required for heating the sludge, respectively; cp sludge T represents the specific heat capacity of sludge. t,air and T t,soil The air and soil temperatures were measured at time t, respectively; k air and k soil These are the heat transfer coefficients of air and soil, respectively; T dig T is the fermentation temperature for anaerobic digestion.so A represents the average influent sludge temperature. sup and A base These are the lateral area and base area of ​​the digester, respectively.

[0041] Furthermore, the CHP unit model is shown below:

[0042] P t,CHP_G =p t,gas L gas η CHP,e (13)

[0043] H t,CHP =p t,gas L gas η CHP,h (14)

[0044] In the formula, P t,CHP_G H represents the total power generation of CHP at time t; t,CHP p is the thermal power of CHP at time t; t,gas L represents the biogas flow rate consumed by CHP at time t. gas η is the calorific value of biogas. CHP,e and η CHP,h The figures represent the electrical and thermal efficiencies of CHP, respectively.

[0045] Furthermore, the energy storage device model includes a battery model and a phase change thermal storage tank model;

[0046] The battery model is shown below:

[0047]

[0048] In the formula, E t,bat and E t-Δt,bat The battery charge stored at time t and time t-Δt are respectively; Δt is time; P t,bat_cha and P t,bat_dis These are the charging and discharging power, respectively. These are the upper and lower limits of charging power; The upper and lower limits of discharge power; 0-1 variable I t,cha To represent the state variable of charging, I t,cha =1 indicates charging, I t,cha =0 indicates no charging; 0-1 variable I t,dis To represent the state variable of discharge, I t,dis =1 indicates discharge, I t,dis =0 indicates no discharge; η cha and η dis These refer to the charging and discharging efficiency of the battery, respectively. and These represent the upper and lower limits of the battery's energy storage capacity; E t,batE represents the battery's energy storage capacity at time t. 0,bat and E T’,bat T' represents the initial and final values ​​of the battery within the scheduling cycle; T' represents the total number of time periods in a scheduling cycle.

[0049] The phase change thermal storage tank model is shown below:

[0050]

[0051] In the formula, H t,bat and H t-Δt,bat The phase change thermal storage tanks store heat at time t and t-Δt, respectively; H t,bat_cha and H t,bat_dis These are the heat storage and heat release capacities, respectively. These are the upper and lower limits of thermal storage capacity; The upper and lower limits of heat release power; 0-1 variable I t,hcha It is a state variable used to represent thermal storage, I t,hcha =1 indicates thermal storage, I t,hcha =0 indicates no heat storage; 0-1 variable I t,hdis It is a state variable used to represent heat release, I t,hdis =1 indicates heat release, I t,hdis =0 indicates no heat release; η hcha and η hdis These refer to the heat storage and heat release efficiencies of the phase change thermal storage tank, respectively. and These represent the upper and lower limits of the thermal storage capacity of the phase change thermal storage tank; H t,bat H represents the thermal storage capacity of the phase change thermal storage tank at time t. 0,bat and H T’,bat These represent the initial and final values ​​of the phase change thermal storage tank within the scheduling cycle.

[0052] 3) Based on the wastewater treatment plant equipment unit model, establish an optimized operation model for the wastewater treatment plant that considers wastewater reuse;

[0053] Furthermore, the objective function of the optimized operation model for wastewater treatment plants considering wastewater reuse is shown below:

[0054]

[0055] In the formula, f t,gas For gas network transaction costs; f t,gird For grid transaction costs; f t,W For revenue from water sales; f t,en For environmental benefits.

[0056] Among them, the gas network transaction cost f t,gas , power grid transaction costs f t,gird Water sales revenue f t,W Environmental benefits ft,en They are shown below:

[0057]

[0058] In the formula, c t,gird and c gas These represent the time-of-use electricity price and gas price at time t, respectively; P t,gird and P t,gas These represent the interaction quantities with the power grid and gas grid at time t, respectively; c W2 and c W3 These are the secondary and tertiary water pricing systems, respectively; Q t,I and Q t,D These represent the secondary and tertiary water demands at time t, respectively; K en2 and K en3 These are the conversion factors for secondary and tertiary emissions, respectively; Q t,en2 Q represents the flow rate of water discharged after secondary treatment at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0059] Furthermore, the constraints of the optimized operation model of the wastewater treatment plant considering wastewater reuse include electrical power balance constraints, gas balance constraints, thermal power balance constraints, secondary water treatment balance constraints, tertiary water treatment balance constraints, upper and lower limits of CHP output constraints, equalization tank constraints, secondary storage tank constraints, and clear water tank constraints.

[0060] The power balance constraints are as follows:

[0061] P t,wind +P t,CHP_G +P t,gird +P t,bat_dis +P t,PV =P t,bat_cha +P t,clar +P t,Aer +P t,3 (19)

[0062] In the formula, P t,PV P represents the power generation capacity of the photovoltaic unit. t,wind P represents the power generation capacity of the wind turbine generator. t,Aer P is the blower power at time t; t,CHP_G P represents the total power generation of CHP at time t. t,gird P represents the interaction with the power grid at time t. t,bat_cha and P t,bat_dis These represent charging and discharging power, respectively; P t,clar P represents the power of the cleaning pump at time t. t,3 The power consumption of the third-level processing at time t;

[0063] The gas balance constraints are as follows:

[0064] p t,BG -p t,gas =P t,gas (20)

[0065] In the formula, p t,gas p is the biogas flow rate consumed by CHP at time t; t,BG Let be the amount of biogas produced at time t;

[0066] The thermal power balance constraints are shown below:

[0067] H t,CHP +H t,bat_dis =H t,loss +H t,sludge +H t,bat_cha (twenty one)

[0068] In the formula, H t,CHP H represents the thermal power of CHP at time t; t,bat_cha and H t,bat_dis These are the heat storage and heat release powers, respectively; H t,loss H t,sludge These are the heat loss from the digester wall and the heat energy required for heating the sludge, respectively.

[0069] The secondary water treatment balance constraints are shown below:

[0070] Q t,2 =α2Q t,se2 (twenty two)

[0071] In the formula, Q t,se2 αt is the flow rate after secondary water treatment at time t; α2 is the secondary water treatment flow rate ratio; Q t,2 Let t be the secondary treated wastewater flow rate.

[0072] The tertiary water treatment balance constraints are shown below:

[0073] Q t,3 =α3Q t,th3 (twenty three)

[0074] In the formula, Q t,th3 α is the flow rate after tertiary water treatment at time t; α3 is the tertiary water treatment flow rate ratio; Q t,3 Let t be the flow rate of the tertiary treatment wastewater.

[0075] The upper and lower limits of CHP output are constrained as follows:

[0076]

[0077] In the formula, and These are the upper and lower limits of CHP's electrical power output; and These represent the upper and lower limits of CHP thermal power output, respectively. t,CHP and Q t,CHP Let be the electrical power and thermal power of CHP at time t, respectively.

[0078] The constraints of the regulating pool are as follows:

[0079]

[0080] In the formula, R t,1 and R t-1,1 Let be the water storage capacity of the regulating tank at time t and time t-1; R represents the maximum water storage capacity of the equalization tank. 0,1 and R T,1 These are the initial and final values ​​within the regulating pool scheduling cycle, respectively; Q t Let t be the flow rate of wastewater entering the equalization tank.

[0081] The constraints of the secondary reservoir are as follows:

[0082]

[0083] In the formula, R t,2 and R t-1,2 Let be the water storage capacity of the secondary reservoir at time t and time t-1; R is the maximum water storage capacity of the secondary reservoir. 0,2 and R T,2 These are the initial and final values ​​within the scheduling cycle of the secondary reservoir; Q t,I Q represents the secondary water demand at time t; t,en2 Let t be the flow rate of water discharged after secondary treatment;

[0084] Clear water pool constraints:

[0085]

[0086] In the formula, R t,3 and R t-1,3 Let be the water volume stored in the clear water tank at time t and time t-1; R is the maximum water storage capacity of the clear water tank. 0,3 and R T,3 These are the beginning and end values ​​within the pool cleaning scheduling cycle, respectively; Q t,D Q represents the tertiary water demand at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0087] 4) Solve the optimal operation model of the wastewater treatment plant that considers wastewater reuse to obtain the optimal operation scheme of the wastewater treatment plant.

[0088] Furthermore, tools for solving optimal operation models of wastewater treatment plants that consider wastewater reuse include CPLEX.

[0089] The technical effects of this invention are undeniable. This invention addresses the problem of neglecting water resource reuse in the operation of existing sewage treatment plants, and fully considers the flexibility and wastewater reuse of sewage treatment plants, providing an optimized operation method for sewage treatment plants that takes wastewater reuse into account.

[0090] This invention fully leverages the flexibility of wastewater treatment plants, enabling them to stabilize loads and perform peak shaving and valley filling, thereby improving economic efficiency and load stability. Attached Figure Description

[0091] Figure 1 This is a flowchart illustrating the solution process of the method of the present invention.

[0092] Figure 2 This is a diagram illustrating the energy flow structure of a wastewater treatment plant that considers wastewater reuse, according to the present invention.

[0093] Figure 3 This is a schematic diagram of a wastewater treatment plant with a tiered treatment process that considers wastewater reuse, according to the present invention.

[0094] Figure 4 This is a comparison chart of secondary treatment water flow rates under three scenarios.

[0095] Figure 5 This is a comparison chart of the flow rates of the three-stage water treatment system under three different scenarios.

[0096] Figure 6 This is a comparison chart of biogas digester temperatures under three different scenarios. Detailed Implementation

[0097] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0098] Example 1:

[0099] See Figures 1 to 6 An optimized operation method for wastewater treatment plants that considers wastewater reuse includes the following steps;

[0100] 1) Obtain the basic parameters of the wastewater treatment plant;

[0101] The basic parameters of the wastewater treatment plant include time-of-use electricity purchase price, time-of-use electricity sales price, gas price, wastewater load, irrigation water load, irrigation water price, secondary discharge revenue, tertiary discharge revenue, industrial miscellaneous water load, and industrial miscellaneous water price.

[0102] 2) Based on the basic parameters of the wastewater treatment plant, model the equipment units of the wastewater treatment plant to obtain the equipment unit model of the wastewater treatment plant;

[0103] The wastewater treatment plant equipment unit model includes a treatment unit model, a sludge-to-biogas production model, a CHP unit model, and an energy storage device model.

[0104] The treatment unit model includes a primary wastewater treatment unit model, a secondary wastewater treatment unit model, and an advanced wastewater treatment model.

[0105] The model for the primary wastewater treatment unit is shown below:

[0106] P t,clar =γ s Q t H t / 1000η (1)

[0107] H t =aQ t 2 +bQ t r+cr 2 (2)

[0108] In the formula, the subscript t indicates time t; P t,clar Let be the power of the cleaning pump at time t; η be the efficiency of the cleaning pump; Q t γ is the wastewater flow velocity entering the equalization tank at time t; s Specific gravity of wastewater; H t Let t be the head of the cleaning pump at time t; r be the relative speed of the cleaning pump; a, b, and c be empirical coefficients of the pump head curve; the coefficients proposed in this embodiment are preset constants.

[0109] The model of a secondary wastewater treatment unit is shown below:

[0110]

[0111] In the formula, P t,Aer R is the blower power at time t; R is the air gas constant; T in η is the inlet temperature of the fan; B P represents the mechanical efficiency of the blower. a Atmospheric pressure; P t,stat P is the static pressure at the outlet of the blower diffuser. t,dyn For dynamic pressure; Q t,air M is the air mass flow rate; air The molecular mass of air;

[0112] Among them, dynamic pressure P t,dyn Air mass flow rate Q t,air They are shown below:

[0113] P t,dyn =(Q t,air / A dif ) 2 k p (4)

[0114]

[0115] In the formula, A dif The diffuser cross-sectional area; coefficient k p =275N s 2 / m 4 ;K La This is the standard oxygen transfer efficiency. This refers to the mass of oxygen per unit mass of air. Standard oxygen transfer rate;

[0116] Standard oxygen transfer rate As shown below:

[0117]

[0118] m t,BOD =Q t,2 (BOD t,in -BOD t,out ConB (7)

[0119] m t,TKN =Q t,2 (TKN t,in -TKN t,out ConN (8)

[0120] In the formula, m t,BOD and m t,TKN The oxygen demand for oxidation and nitrification in the aeration tank are represented by β; β is the mass of oxygen per unit mass of air; C T and C T 0 At temperature T and reference temperature T, respectively. 0 Oxygen saturation concentration in freshwater; C d α is the dissolved oxygen concentration; θ is the oxygen transfer ratio in the wastewater; θ is a constant; BOD t,in and BOD t,out The concentrations of BOD (Biochemical Oxygen Demand) in the influent and effluent of the wastewater treatment plant; TKN t,in and TKN t,out TKN (Total Kjeldahl Nitrogen) concentration in the influent and effluent of the wastewater treatment plant; ConN is the oxygen ratio required to oxidize TKN; ConB is the oxygen ratio required to oxidize BOD; Q t,2 The flow rate for secondary treatment wastewater;

[0121] The advanced wastewater treatment model is shown below:

[0122] P t,3 =η3V t,3 (9)

[0123] In the formula, η3 is the volume coefficient of wastewater treated per unit of electrical energy in the tertiary treatment stage; V t,3 P represents the volume of water entering the clear water tank after three stages of treatment at time t. t,3 The power consumption of the third-level processing at time t.

[0124] The sludge-to-biogas model includes equations for calculating biogas production, heat loss from the digester wall, and heat energy required for heating the sludge.

[0125] The equation for calculating biogas production is shown below:

[0126]

[0127] In the formula, the subscript t indicates time t; m sl,t Let β be the sludge mass at time t; wsl p represents the sludge coefficient after wastewater has settled and settled. t,BG Let be the amount of biogas produced at time t; Reference temperature T 0 The sludge biogas production coefficient under the specified conditions; f t (T dig T represents the fermentation temperature T in the biogas digester at time t. dig Biogas production rate; f t (T 0 ρ represents the biogas production rate of the biogas digester at a reference temperature T0 at time t; wsl The average density of the wastewater after it has been left to stand and settle.

[0128] Among them, the gas production rate f t (T dig ) and fermentation temperature T dig The relationship is as follows:

[0129] f t (T dig )=m(T dig -T0) 2 +n (11)

[0130] In the formula, m and n are the coefficients in the quadratic expression;

[0131] The equations for calculating heat loss from the digester wall and the equations for calculating the heat energy required for sludge heating are as follows:

[0132] Heat loss H from the digester wall t,loss The heat energy required for heating sludge Ht,sludge for:

[0133]

[0134] In the formula, H t,loss H t,sludge These represent the heat loss from the digester wall and the heat energy required for heating the sludge, respectively; cp sludge T represents the specific heat capacity of sludge. t,air and T t,soil The air and soil temperatures were measured at time t, respectively; k air and k soil These are the heat transfer coefficients of air and soil, respectively; T dig T is the fermentation temperature for anaerobic digestion. so A represents the average influent sludge temperature. sup and A base These are the lateral area and base area of ​​the digester, respectively.

[0135] The CHP (Combined Heat and Power) unit model is shown below:

[0136] P t,CHP_G =p t,gas L gas η CHP,e (13)

[0137] H t,CHP =p t,gas L gas η CHP,h (14)

[0138] In the formula, P t,CHP_G H represents the total power generation of CHP at time t; t,CHP p is the thermal power of CHP at time t; t,gas L represents the biogas flow rate consumed by CHP at time t. gas η is the calorific value of biogas. CHP,e and η CHP,h The figures represent the electrical and thermal efficiencies of CHP, respectively.

[0139] The energy storage device model includes a battery model and a phase change thermal storage tank model;

[0140] The battery model is shown below:

[0141]

[0142] In the formula, E t,bat and E t-Δt,bat The battery charge stored at time t and time t-Δt are respectively; Δt is time; P t,bat_cha and P t,bat_disThese are the charging and discharging power, respectively. These are the upper and lower limits of charging power; The upper and lower limits of discharge power; 0-1 variable I t,cha To represent the state variable of charging, I t,cha =1 indicates charging, I t,cha =0 indicates no charging; 0-1 variable I t,dis To represent the state variable of discharge, I t,dis =1 indicates discharge, I t,dis =0 indicates no discharge; η cha and η dis These refer to the charging and discharging efficiency of the battery, respectively. and These represent the upper and lower limits of the battery's energy storage capacity; E t,bat E represents the battery's energy storage capacity at time t. 0,bat and E T’,bat T' represents the initial and final values ​​of the battery within the scheduling cycle; T' represents the total number of time periods in a scheduling cycle.

[0143] The phase change thermal storage tank model is shown below:

[0144]

[0145] In the formula, H t,bat and H t-Δt,bat The phase change thermal storage tanks store heat at time t and t-Δt, respectively; H t,bat_cha and H t,bat_dis These are the heat storage and heat release capacities, respectively. These are the upper and lower limits of thermal storage capacity; The upper and lower limits of heat release power; 0-1 variable I t,hcha It is a state variable used to represent thermal storage, I t,hcha =1 indicates thermal storage, I t,hcha =0 indicates no heat storage; 0-1 variable I t,hdis It is a state variable used to represent heat release, I t,hdis =1 indicates heat release, I t,hdis =0 indicates no heat release; η hcha and η hdis These refer to the heat storage and heat release efficiencies of the phase change thermal storage tank, respectively. and These represent the upper and lower limits of the thermal storage capacity of the phase change thermal storage tank; H t,bat H represents the thermal storage capacity of the phase change thermal storage tank at time t. 0,bat and H T’,bat These represent the initial and final values ​​of the phase change thermal storage tank within the scheduling cycle.

[0146] 3) Based on the wastewater treatment plant equipment unit model, establish an optimized operation model for the wastewater treatment plant that considers wastewater reuse;

[0147] The objective function of the optimized operation model for a wastewater treatment plant considering wastewater reuse is shown below:

[0148]

[0149] In the formula, f t,gas For gas network transaction costs; f t,gird For grid transaction costs; f t,W For revenue from water sales; f t,en For environmental benefits.

[0150] Among them, the gas network transaction cost f t,gas , power grid transaction costs f t,gird Water sales revenue f t,W Environmental benefits f t,en They are shown below:

[0151]

[0152] In the formula, c t,gird and c gas These represent the time-of-use electricity price and gas price at time t, respectively; P t,gird and P t,gas These represent the interaction quantities with the power grid and gas grid at time t, respectively; c W2 and c W3 These are the secondary and tertiary water pricing systems, respectively; Q t,I and Q t,D These represent the secondary and tertiary water demands at time t, respectively; K en2 and K en3 These are the conversion factors for secondary and tertiary emissions, respectively; Q t,en2 Q represents the flow rate of water discharged after secondary treatment at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0153] The constraints of the optimized operation model of a wastewater treatment plant considering wastewater reuse include electrical power balance constraints, gas balance constraints, thermal power balance constraints, secondary water treatment balance constraints, tertiary water treatment balance constraints, upper and lower limits of CHP output constraints, equalization tank constraints, secondary storage tank constraints, and clear water tank constraints.

[0154] The power balance constraints are as follows:

[0155] P t,wind +P t,CHP_G +P t,gird +P t,bat_dis +P t,PV =P t,bat_cha +P t,clar +P t,Aer +P t,3 (19)

[0156] In the formula, P t,PV P represents the power generation capacity of the photovoltaic unit. t,wind P represents the power generation capacity of the wind turbine generator. t,Aer P is the blower power at time t; t,CHP_G P represents the total power generation of CHP at time t. t,gird P represents the interaction with the power grid at time t. t,bat_cha and P t,bat_dis These represent charging and discharging power, respectively; P t,clar P represents the power of the cleaning pump at time t. t,3 The power consumption of the third-level processing at time t;

[0157] The gas balance constraints are as follows:

[0158] p t,BG -p t,gas =P t,gas (20)

[0159] In the formula, p t,gas p is the biogas flow rate consumed by CHP at time t; t,BG Let be the amount of biogas produced at time t;

[0160] The thermal power balance constraints are shown below:

[0161] H t,CHP +H t,bat_dis =H t,loss +H t,sludge +H t,bat_cha (twenty one)

[0162] In the formula, H t,CHP H represents the thermal power of CHP at time t; t,bat_cha and H t,bat_dis These are the heat storage and heat release powers, respectively; H t,loss H t,sludge These are the heat loss from the digester wall and the heat energy required for heating the sludge, respectively.

[0163] The secondary water treatment balance constraints are shown below:

[0164] Q t,2 =α2Q t,se2 (twenty two)

[0165] In the formula, Q t,se2 αt is the flow rate after secondary water treatment at time t; α2 is the secondary water treatment flow rate ratio; Q t,2 Let t be the secondary treated wastewater flow rate.

[0166] The tertiary water treatment balance constraints are shown below:

[0167] Q t,3 =α3Qt,th3 (twenty three)

[0168] In the formula, Q t,th3 α is the flow rate after tertiary water treatment at time t; α3 is the tertiary water treatment flow rate ratio; Q t,3 Let t be the flow rate of the tertiary treatment wastewater.

[0169] The upper and lower limits of CHP output are constrained as follows:

[0170]

[0171] In the formula, and These are the upper and lower limits of CHP's electrical power output; and These represent the upper and lower limits of CHP thermal power output, respectively. t,CHP and Q t,CHP Let be the electrical power and thermal power of CHP at time t, respectively.

[0172] The constraints of the regulating pool are as follows:

[0173]

[0174] In the formula, R t,1 and R t-1,1 Let be the water storage capacity of the regulating tank at time t and time t-1; R represents the maximum water storage capacity of the equalization tank. 0,1 and R T,1 These are the initial and final values ​​within the regulating pool scheduling cycle, respectively; Q t Let t be the flow rate of wastewater entering the equalization tank.

[0175] The constraints of the secondary reservoir are as follows:

[0176]

[0177] In the formula, R t,2 and R t-1,2 Let be the water storage capacity of the secondary reservoir at time t and time t-1; R is the maximum water storage capacity of the secondary reservoir. 0,2 and R T,2 These are the initial and final values ​​within the scheduling cycle of the secondary reservoir; Q t,I Q represents the secondary water demand at time t; t,en2 Let t be the flow rate of water discharged after secondary treatment;

[0178] Clear water pool constraints:

[0179]

[0180] In the formula, R t,3 and Rt-1,3 Let be the water volume stored in the clear water tank at time t and time t-1; R is the maximum water storage capacity of the clear water tank. 0,3 and R T,3 These are the beginning and end values ​​within the pool cleaning scheduling cycle, respectively; Q t,D Q represents the tertiary water demand at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0181] 4) Solve the optimal operation model of the wastewater treatment plant that considers wastewater reuse to obtain the optimal operation scheme of the wastewater treatment plant.

[0182] Tools for solving optimal operation models of wastewater treatment plants that consider wastewater reuse include CPLEX.

[0183] Example 2:

[0184] An optimized operation method for a wastewater treatment plant considering wastewater reuse includes the following steps;

[0185] 1) Obtain the basic parameters of the wastewater treatment plant;

[0186] 2) Based on the basic parameters of the wastewater treatment plant, model the equipment units of the wastewater treatment plant to obtain the equipment unit model of the wastewater treatment plant;

[0187] 3) Based on the wastewater treatment plant equipment unit model, establish an optimized operation model for the wastewater treatment plant that considers wastewater reuse;

[0188] 4) Solve the optimal operation model of the wastewater treatment plant that considers wastewater reuse to obtain the optimal operation scheme of the wastewater treatment plant.

[0189] Example 3:

[0190] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 2. The basic parameters of the wastewater treatment plant include time-of-use electricity price, time-of-use electricity price, gas price, wastewater load, irrigation water load, irrigation water price, secondary discharge revenue, tertiary discharge revenue, industrial miscellaneous water load, and industrial miscellaneous water price.

[0191] Example 4:

[0192] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 2. The wastewater treatment plant equipment unit model includes a treatment unit model, a sludge biogas production model, a CHP unit model, and an energy storage device model.

[0193] Example 5:

[0194] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 4. The treatment unit model includes a primary wastewater treatment unit model, a secondary wastewater treatment unit model, and an advanced wastewater treatment model.

[0195] The model for the primary wastewater treatment unit is shown below:

[0196] P t,clar =γ s Q t H t / 1000η (1)

[0197] H t =aQ t 2 +bQ t r+cr 2 (2)

[0198] In the formula, the subscript t indicates time t; P t,clar Let be the power of the cleaning pump at time t; η be the efficiency of the cleaning pump; Q t γ is the wastewater flow velocity entering the equalization tank at time t; s Specific gravity of wastewater; H t Let t be the head of the cleaning pump; r be the relative speed of the cleaning pump; and a, b, and c be empirical coefficients for the pump head curve.

[0199] The model of a secondary wastewater treatment unit is shown below:

[0200]

[0201] In the formula, P t,Aer R is the blower power at time t; R is the air gas constant; T in η is the inlet temperature of the fan; B P represents the mechanical efficiency of the blower. a Atmospheric pressure; P t,stat P is the static pressure at the outlet of the blower diffuser. t,dyn For dynamic pressure; Q t,air Air mass flow rate;

[0202] Among them, dynamic pressure P t,dyn Air mass flow rate Q t,air They are shown below:

[0203] P t,dyn =(Q t,air / A dif ) 2 k p (4)

[0204]

[0205] In the formula, A dif The diffuser cross-sectional area; coefficient k p =275N s 2 / m 4 ;K La This is the standard oxygen transfer efficiency. This refers to the mass of oxygen per unit mass of air. Standard oxygen transfer rate;

[0206] Standard oxygen transfer rate As shown below:

[0207]

[0208] m t,BOD =Q t,2 (BOD t,in -BOD t,out ConB (7)

[0209] m t,TKN =Q t,2 (TKN t,in -TKN t,out ConN (8)

[0210] In the formula, m t,BOD and m t,TKN The oxygen demand for oxidation and nitrification in the aeration tank are represented by β; β is the mass of oxygen per unit mass of air; C T and C T 0 At temperature T and reference temperature T, respectively. 0 Oxygen saturation concentration in freshwater; C d α is the dissolved oxygen concentration; θ is the oxygen transfer ratio in the wastewater; θ is a constant; BOD t,in and BOD t,out The BOD concentration of the influent and effluent of the wastewater treatment plant; TKN t,in and TKN t,out TKN concentration in the influent and effluent of the wastewater treatment plant; ConN is the oxygen ratio required for TKN oxidation; ConB is the oxygen ratio required for BOD oxidation; Q t,2 The flow rate for secondary treatment wastewater;

[0211] The advanced wastewater treatment model is shown below:

[0212] P t,3 =η3V t,3 (9)

[0213] In the formula, η3 is the volume coefficient of wastewater treated per unit of electrical energy in the tertiary treatment stage; V t,3P represents the volume of water entering the clear water tank after three stages of treatment at time t. t,3 The power consumption of the third-level processing at time t.

[0214] Example 6:

[0215] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 4. The sludge-to-biogas model includes equations for calculating biogas production, heat loss from the digester wall, and heat energy required for sludge heating.

[0216] The equation for calculating biogas production is shown below:

[0217]

[0218] In the formula, the subscript t indicates time t; m t,sl Let β be the sludge mass at time t; wsl p represents the sludge coefficient after wastewater has settled and settled. t,BG Let be the amount of biogas produced at time t; Reference temperature T 0 The sludge biogas production coefficient under the specified conditions; f t (T dig T represents the fermentation temperature T in the biogas digester at time t. dig Biogas production rate; f t (T 0 () represents the biogas production rate of the biogas digester at reference temperature T0 at time t;

[0219] Among them, the gas production rate f t (T dig ) and fermentation temperature T dig The relationship is as follows:

[0220] f t (T dig )=m(T dig -T0) 2 +n (2)

[0221] In the formula, m and n are the coefficients in the quadratic expression;

[0222] The equations for calculating heat loss from the digester wall and the equations for calculating the heat energy required for sludge heating are as follows:

[0223] Heat loss H from the digester wall t,loss The heat energy required for heating sludge (H) t,sludge for:

[0224]

[0225] In the formula, H t,loss H t,sludgeThese represent the heat loss from the digester wall and the heat energy required for heating the sludge, respectively; cp sludge T represents the specific heat capacity of sludge. t,air and T t,soil The air and soil temperatures were measured at time t, respectively; k air and k soil These are the heat transfer coefficients of air and soil, respectively; T dig T is the fermentation temperature for anaerobic digestion. so A represents the average influent sludge temperature. sup and A base These are the lateral area and base area of ​​the digester, respectively.

[0226] Example 7:

[0227] An optimized operation method for wastewater treatment plants considering wastewater reuse is described in Example 4, where the CHP unit model is shown below:

[0228] P t,CHP_G =p t,gas L gas η CHP,e (1)

[0229] H t,CHP =p t,gas L gas η CHP,h (2)

[0230] In the formula, P t,CHP_G H represents the total power generation of CHP at time t; t,CHP p is the thermal power of CHP at time t; t,gas L represents the biogas flow rate consumed by CHP at time t. gas η is the calorific value of biogas. CHP,e and η CHP,h The figures represent the electrical and thermal efficiencies of CHP, respectively.

[0231] Example 8:

[0232] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 4. The energy storage device model includes a battery model and a phase change thermal storage tank model.

[0233] The battery model is shown below:

[0234]

[0235] In the formula, E t,bat and E t-Δt,bat The battery charge stored at time t and time t-Δt are respectively; Δt is time; P t,bat_cha and P t,bat_dis These are the charging and discharging power, respectively. These are the upper and lower limits of charging power; The upper and lower limits of discharge power; 0-1 variable I t,cha To represent the state variable of charging, I t,cha =1 indicates charging, I t,cha =0 indicates no charging; 0-1 variable I t,dis To represent the state variable of discharge, I t,dis =1 indicates discharge, I t,dis =0 indicates no discharge; η cha and η dis These refer to the charging and discharging efficiency of the battery, respectively. and These represent the upper and lower limits of the battery's energy storage capacity; E t,bat E represents the battery's energy storage capacity at time t. 0,bat and E T’,bat T' represents the initial and final values ​​of the battery within the scheduling cycle; T' represents the total number of time periods in a scheduling cycle.

[0236] The phase change thermal storage tank model is shown below:

[0237]

[0238] In the formula, H t,bat and H t-Δt,bat The phase change thermal storage tanks store heat at time t and t-Δt, respectively; H t,bat_cha and H t,bat_dis These are the heat storage and heat release capacities, respectively. These are the upper and lower limits of thermal storage capacity; The upper and lower limits of heat release power; 0-1 variable I t,hcha It is a state variable used to represent thermal storage, I t,hcha =1 indicates thermal storage, I t,hcha =0 indicates no heat storage; 0-1 variable I t,hdis It is a state variable used to represent heat release, I t,hdis =1 indicates heat release, I t,hdis =0 indicates no heat release; η hcha and η hdis These refer to the heat storage and heat release efficiencies of the phase change thermal storage tank, respectively. and These represent the upper and lower limits of the thermal storage capacity of the phase change thermal storage tank; H t,bat H represents the thermal storage capacity of the phase change thermal storage tank at time t. 0,bat and H T’,bat These represent the initial and final values ​​of the phase change thermal storage tank within the scheduling cycle.

[0239] Example 9:

[0240] An optimized operation method for wastewater treatment plants considering wastewater reuse is described in Example 2. The objective function of the optimized operation model for wastewater treatment plants considering wastewater reuse is shown below:

[0241]

[0242] In the formula, f t,gas For gas network transaction costs; f t,gird For grid transaction costs; f t,W For revenue from water sales; f t,en For environmental benefits.

[0243] Among them, the gas network transaction cost f t,gas , power grid transaction costs f t,gird Water sales revenue f t,W Environmental benefits f t,en They are shown below:

[0244]

[0245] In the formula, c t,gird and c gas These represent the time-of-use electricity price and gas price at time t, respectively; P t,gird and P t,gas These represent the interaction quantities with the power grid and gas grid at time t, respectively; c W2 and c W3 These are the secondary and tertiary water pricing systems, respectively; Q t,I and Q t,D These represent the secondary and tertiary water demands at time t, respectively; K en2 and K en3 These are the conversion factors for secondary and tertiary emissions, respectively; Q t,en2 Q represents the flow rate of water discharged after secondary treatment at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0246] Example 10:

[0247] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 2. The constraints of the optimized operation model for the wastewater treatment plant considering wastewater reuse include electrical power balance constraints, gas balance constraints, thermal power balance constraints, secondary water treatment balance constraints, tertiary water treatment balance constraints, upper and lower limits of CHP output constraints, equalization tank constraints, secondary storage tank constraints, and clear water tank constraints.

[0248] The power balance constraints are as follows:

[0249] P t,wind +P t,CHP_G +P t,gird +P t,bat_dis +Pt,PV =P t,bat_cha +P t,clar +P t,Aer +P t,3 (1)

[0250] In the formula, P t,PV P represents the power generation capacity of the photovoltaic unit. t,wind P represents the power generation capacity of the wind turbine generator. t,Aer P is the blower power at time t; t,CHP_G P represents the total power generation of CHP at time t. t,gird P represents the interaction with the power grid at time t. t,bat_cha and P t,bat_dis These represent charging and discharging power, respectively; P t,clar P represents the power of the cleaning pump at time t. t,3 The power consumption of the third-level processing at time t;

[0251] The gas balance constraints are as follows:

[0252] p t,BG -p t,gas =P t,gas (2)

[0253] In the formula, p t,gas p is the biogas flow rate consumed by CHP at time t; t,BG Let be the amount of biogas produced at time t;

[0254] The thermal power balance constraints are shown below:

[0255] H t,CHP +H t,bat_dis =H t,loss +H t,sludge +H t,bat_cha (3)

[0256] In the formula, H t,CHP H represents the thermal power of CHP at time t; t,bat_cha and H t,bat_dis These are the heat storage and heat release powers, respectively; H t,loss H t,sludge These are the heat loss from the digester wall and the heat energy required for heating the sludge, respectively.

[0257] The secondary water treatment balance constraints are shown below:

[0258] Q t,2 =α2Q t,se2 (4)

[0259] In the formula, Q t,se2 αt is the flow rate after secondary water treatment at time t; α2 is the secondary water treatment flow rate ratio; Q t,2 Let t be the secondary treated wastewater flow rate.

[0260] The tertiary water treatment balance constraints are shown below:

[0261] Q t,3 =α3Q t,th3 (5)

[0262] In the formula, Q t,th3 α is the flow rate after tertiary water treatment at time t; α3 is the tertiary water treatment flow rate ratio; Q t,2 Let t be the flow rate of the tertiary treatment wastewater.

[0263] The upper and lower limits of CHP output are constrained as follows:

[0264]

[0265] In the formula, and These are the upper and lower limits of CHP's electrical power output; and These represent the upper and lower limits of CHP thermal power output, respectively. t,CHP and Q t,CHP Let be the electrical power and thermal power of CHP at time t, respectively.

[0266] The constraints of the regulating pool are as follows:

[0267]

[0268] In the formula, R t,1 and R t-1,1 Let be the water storage capacity of the regulating tank at time t and time t-1; R represents the maximum water storage capacity of the equalization tank. 0,1 and R T,1 These are the initial and final values ​​within the regulating pool scheduling cycle, respectively; Q t Let t be the flow rate of wastewater entering the equalization tank.

[0269] The constraints of the secondary reservoir are as follows:

[0270]

[0271] In the formula, R t,2 and R t-1,2 Let be the water storage capacity of the secondary reservoir at time t and time t-1; R is the maximum water storage capacity of the secondary reservoir. 0,2 and R T,2 These are the initial and final values ​​within the scheduling cycle of the secondary reservoir; Q t,I Q represents the secondary water demand at time t; t,en2 Let t be the flow rate of water discharged after secondary treatment;

[0272] Clear water pool constraints:

[0273]

[0274] In the formula, R t,3 and R t-1,3 R represents the water volume stored in the clear water tank at time t and time t-1. max3 R is the maximum water storage capacity of the clear water tank. 0,3 and R T,3 These are the beginning and end values ​​within the pool cleaning scheduling cycle, respectively; Q t,D Q represents the tertiary water demand at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0275] Example 11:

[0276] An optimized operation method for a wastewater treatment plant considering wastewater reuse is described in Example 2. The tool for solving the optimized operation model of the wastewater treatment plant considering wastewater reuse includes CPLEX.

[0277] Example 12:

[0278] An optimized operation method for wastewater treatment plants considering wastewater reuse is described below:

[0279] A wastewater treatment plant considering wastewater reuse includes treatment units and equipment units at various levels; the treatment units at each level include equalization tanks, cleaning pumps, primary sedimentation tanks, blowers, biological denitrification tanks, secondary sedimentation tanks, secondary storage tanks, advanced treatment units, clear water tanks, and filter membranes; the equipment units include photovoltaic generator sets, wind turbine generator sets, biogas generators, biogas digesters, electric boilers, batteries, and thermal storage tanks; characterized in that: the wastewater treatment plant is also equipped with lines and pipelines to achieve interaction with the power grid and gas grid; the electric boiler transfers heat energy to the thermal storage tanks and biogas digesters via heat pipes.

[0280] The technical solution of this invention is: a method for optimizing the operation of a wastewater treatment plant considering wastewater reuse. The main steps of this method are as follows: Step 1: First, input the basic parameters of the wastewater treatment plant. Step 2: Model each unit in the wastewater treatment plant. Step 3: Establish the objective function and constraints for optimizing the operation of the wastewater treatment plant considering wastewater reuse. After piecewise linearization of the nonlinear constraints, use the commercial solver CPLEX to solve the problem and obtain the optimal solution. Specific implementation steps are as follows:

[0281] Input basic data

[0282] 1.1 Input basic data

[0283] Input the basic parameters of the wastewater treatment plant, including: time-of-use electricity purchase price, time-of-use electricity sales price, gas price, wastewater load, irrigation water load, irrigation water price, secondary discharge revenue, tertiary discharge revenue, industrial miscellaneous water load, and industrial miscellaneous water price.

[0284] Wastewater treatment plant unit models

[0285] 2.1 Processing Models at Each Level

[0286] The power consumption of the primary treatment is mainly due to the cleaning pump:

[0287] P t,clar =γ s Q t H t / 1000η (1)

[0288] H t =aQ t 2 +bQ t r+cr 2 (2)

[0289] In the formula, the subscript t indicates time t, and P t,clar Let be the power of the cleaning pump at time t; η be the efficiency of the cleaning pump; Q t γ is the wastewater flow velocity entering the equalization tank at time t; s Specific gravity of wastewater; H t Let t be the head of the cleaning pump at time t; r be the relative speed of the cleaning pump; and a, b, and c be empirical coefficients for the pump head curve.

[0290] In the secondary wastewater treatment model, the power consumption of the aeration unit mainly comes from the power consumption of the blower.

[0291]

[0292] In the formula, the subscript t indicates time t, and P t,Aer R is the blower power at time t; R is the air gas constant; T in η is the inlet temperature of the fan; B P represents the mechanical efficiency of the blower. a Atmospheric pressure; P t,stat This refers to the static pressure at the outlet of the blower diffuser.

[0293] Dynamic pressure P t,dyn It can be calculated using the following formula:

[0294] P t,dyn =(Q t,air / A dif ) 2 k p (4)

[0295] In the formula, the subscript t indicates time t, and Q t,air For air mass flow rate; A dif k is the cross-sectional area of ​​the diffuser. p =275Ns 2 / m 4

[0296] Air mass flow rate Q t,air It can be calculated using the following formula:

[0297]

[0298] In the formula, the subscript t indicates time t, and K La n is the standard oxygen transport efficiency. O2 The mass of oxygen per unit mass of air, m t,O2 This is the standard oxygen transfer rate.

[0299] The standard oxygen transfer rate can be calculated using the following formula:

[0300]

[0301] m t,BOD =Q t,2 (BOD t,in -BOD t,out ConB (7)

[0302] m t,TKN =Q t,2 (TKN t,in -TKN t,out ConN (8)

[0303] In the formula, the subscript t indicates time t, and m t,BOD and m t,TKN The oxygen demand for oxidation and nitrification in the aeration tank are represented by β, where β is the mass of oxygen per unit mass of air, and C is the mass of oxygen per unit mass of air. T and C T 0 The oxygen saturation concentrations in freshwater at temperatures T and a reference temperature, respectively, are C. d α is the dissolved oxygen concentration, θ is the oxygen transfer ratio in the wastewater, and θ is a constant. BOD t,in and BOD t,out TKN represents the BOD concentration of the influent and effluent of a wastewater treatment plant. t,in and TKN t,out Here, TKN is the concentration of influent and effluent from the wastewater treatment plant; ConN is the oxygen ratio required to oxidize TKN; CONB is the oxygen ratio required to oxidize BOD; and Q... t,2 This refers to the flow rate of wastewater undergoing secondary treatment.

[0304] Deep processing model:

[0305] P t,3 =η3V t,3 (9)

[0306] In the formula, η3 is the volume coefficient of wastewater treated per unit of electrical energy in the tertiary treatment stage; V t,3 P represents the volume of water entering the clear water tank after three stages of treatment at time t. t,3 The power consumption of the third-level processing at time t.

[0307] 2.2 Sludge-to-biogas production model

[0308] The sludge obtained from the secondary treatment process is then subjected to anaerobic digestion to obtain biogas. The biogas yield is:

[0309]

[0310] In the formula, the subscript t indicates time t; m t,sl Let β be the sludge mass at time t; wsl p represents the sludge coefficient after wastewater has settled and settled. t,BG β represents the amount of biogas produced at time t; S2B,T0 This represents the sludge biogas production coefficient at temperature T0, which is typically 35℃. t (T dig T represents the fermentation temperature T in the biogas digester at time t. dig The biogas production rate.

[0311] The relationship between biogas yield and fermentation temperature can be expressed as:

[0312] f t (T dig )=m(T dig -T0) 2 +n (11)

[0313] In the formula, m and n are the coefficients in the quadratic expression.

[0314] Heat loss H from the digester wall t,loss The heat energy required for heating sludge (H) t,sludge for:

[0315]

[0316] In the formula, cp sludge The specific heat capacity of sludge is 3.62 kJ / kg℃; T air and T soil Temperatures were measured in air and soil, respectively; k air and k soil These are the heat transfer coefficients of air and soil, respectively; T dig The fermentation temperature is the temperature for anaerobic digestion, while the average influent sludge temperature T is... soIt should be 15℃; A sup and A base These are the lateral area and base area of ​​the digester, respectively, in m. 2 .

[0317] 2.3 CHP Unit Model

[0318] The CHP unit model is as follows:

[0319] P t,CHP_G =p t,gas L gas η CHP,e (13)

[0320] H t,CHP =p t,gas L gas η CHP,h (14)

[0321] In the formula, P t,CHP_G H represents the total power generation of CHP at time t; t,CHP p is the thermal power of CHP at time t; t,gas L represents the biogas flow rate consumed by CHP at time t. gas η is the calorific value of biogas. CHP,e and η CHP,h The figures represent the electrical and thermal efficiencies of CHP, respectively.

[0322] 2.4 Energy Storage Device

[0323] Wastewater treatment plants are equipped with storage batteries and phase change thermal storage tanks;

[0324] The battery model is shown below:

[0325]

[0326] In the formula, E t,bat and E t-Δt,bat The battery charge stored at time t and time t-Δt are respectively; Δt is time; P t,bat_cha and P t,bat_dis These are the charging and discharging power, respectively. These are the upper and lower limits of charging power; The upper and lower limits of discharge power; 0-1 variable I t,cha To represent the state variable of charging, I t,cha =1 indicates charging, I t,cha =0 indicates no charging; 0-1 variable I t,dis To represent the state variable of discharge, I t,dis =1 indicates discharge, I t,dis =0 indicates no discharge; η cha and η dis These refer to the charging and discharging efficiency of the battery, respectively. and These are the upper and lower limits of the battery's energy storage capacity, respectively. Et,bat E represents the battery's energy storage capacity at time t. 0,bat and E T’,bat T' represents the initial and final values ​​of the battery within the scheduling cycle; T' represents the total number of time periods in a scheduling cycle.

[0327] The phase change thermal storage tank model is shown below:

[0328]

[0329] In the formula, H t,bat and H t-Δt,bat The phase change thermal storage tanks store heat at time t and t-Δt, respectively; H t,bat_cha and H t,bat_dis These are the heat storage and heat release capacities, respectively. These are the upper and lower limits of thermal storage capacity; The upper and lower limits of heat release power; 0-1 variable I t,hcha It is a state variable used to represent thermal storage, I t,hcha =1 indicates thermal storage, I t,hcha =0 indicates no heat storage; 0-1 variable I t,hdis It is a state variable used to represent heat release, I t,hdis =1 indicates heat release, I t,hdis =0 indicates no heat release; η hcha and η hdis These refer to the heat storage and heat release efficiencies of the phase change thermal storage tank, respectively. and These represent the upper and lower limits of the thermal storage capacity of the phase change thermal storage tank; H t,bat H represents the thermal storage capacity of the phase change thermal storage tank at time t. 0,bat and H T’,bat These represent the initial and final values ​​of the phase change thermal storage tank within the scheduling cycle.

[0330] Establish the objective function and constraints for optimal operation and solve them.

[0331] 3.1 Establish the objective function that minimizes operating costs

[0332] Based on the above model, the following objective function is established:

[0333]

[0334] In the formula, f t,gas For transaction costs with the gas network; f t,gird For grid transaction costs; f t,W For revenue from water sales; f t,en For environmental benefits.

[0335] Each cost and benefit is calculated using the following formula:

[0336]

[0337] In the formula, c t,gird and c gas These represent the time-of-use electricity price and gas price at time t, respectively; P t,gird and P t,gas These represent the interaction quantities with the power grid and gas grid at time t, respectively; c W2 and c W3 These are the secondary and tertiary water pricing systems, respectively; Q t,I and Q t,D These represent the secondary and tertiary water demands at time t, respectively; K en2 and K en3 These are the conversion factors for secondary and tertiary emissions, respectively; Q t,en2 Q represents the flow rate of water discharged after secondary treatment at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

[0338] 3.2 Establish various constraints

[0339] The power balance constraint is:

[0340] P t,wind +P t,CHP_G +P t,gird +P t,bat_dis +P t,PV =P t,bat_cha +P t,clar +P t,Aer +P t,3 (19)

[0341] In the formula, P t,PV P represents the power generation capacity of the photovoltaic unit. t,wind The power generation capacity of the wind turbine.

[0342] Gas balance constraints:

[0343] p t,BG -p t,gas =P t,gas (20)

[0344] Thermal power balance constraint:

[0345] H t,CHP +H t,bat_dis =H t,loss +H t,sludge +H t,bat_cha (twenty one)

[0346] Secondary water treatment balance constraints:

[0347] Q t,2 =α2Q t,se2(twenty two)

[0348] In the formula, Q t,se2 α1 is the flow rate after secondary water treatment at time t; α2 is the flow rate ratio after secondary water treatment.

[0349] Tertiary water treatment balance constraints:

[0350] Q t,3 =α3Q t,th3 (twenty three)

[0351] In the formula, Q t,th3 α is the flow rate after tertiary water treatment at time t; α3 is the tertiary water treatment flow rate ratio.

[0352] CHP output upper and lower limit constraints:

[0353]

[0354] In the formula, and These are the upper and lower limits of CHP's electrical power output; and These are the upper and lower limits of CHP thermal power output, respectively.

[0355] Adjustment pool constraints:

[0356]

[0357] In the formula, R t,1 Let t be the water storage capacity of the regulating tank at time t; R is the maximum water storage capacity of the equalization tank. 0,1 and R T,1 These are the initial and final values ​​within the regulation pool scheduling cycle, respectively.

[0358] Constraints of the secondary reservoir:

[0359]

[0360] In the formula, R t,2 R represents the water storage capacity of the secondary reservoir at time t; max2 R is the maximum water storage capacity of the secondary reservoir. 0,2 and R T,2 These are the beginning and end values ​​within the scheduling cycle of the secondary reservoir.

[0361] Clear water pool constraints:

[0362]

[0363] In the formula, R t,3 R represents the water volume in the clear water tank at time t; max3 R is the maximum water storage capacity of the clear water tank. 0,3 and RT,3 These are the beginning and end values ​​within the pool cleaning scheduling cycle, respectively.

[0364] 3.3 Constraint Handling and Solution

[0365] Equations (1)-(8) and (10)-(11) are piecewise linearized and then solved using the CPLEX solver.

[0366] Example 13:

[0367] A verification experiment of the optimized operation method of a wastewater treatment plant considering wastewater reuse, as described in Examples 1-12, is as follows:

[0368] 1) The wastewater treatment plant considering wastewater reuse is equipped with a tiered treatment system, including an equalization tank, a secondary storage tank, a clear water tank, primary treatment, secondary treatment, and tertiary treatment. The primary treatment includes pumps and a primary sedimentation tank. The secondary treatment includes blowers, an anoxic / aerobic (A / O) tank, and a secondary sedimentation tank. The tertiary treatment includes a tertiary treatment tank. Wastewater first enters the equalization tank to ensure uniform water quality. After filtration in the primary sedimentation tank, it enters the A / O tank for anoxic denitrification, aerobic organic matter removal, and nitrification stages with aeration. Sludge is obtained in the secondary sedimentation tank. The secondary-treated water can be used for agricultural irrigation and for discharge to generate wastewater benefits. The sludge is then anaerobic treated to reduce its volume and generate biogas for power generation or heating. Finally, the tertiary-treated wastewater is used for miscellaneous industrial applications and for discharge to generate wastewater benefits. The wastewater treatment plant is equipped with an equalization tank, a secondary storage tank, and a clear water tank to achieve flexible tiered control.

[0369] As attached Figure 2 As shown, an energy flow for a wastewater treatment plant considering wastewater reuse includes electrical energy, thermal energy, water, and biogas. Specifically: the electrical busbar is connected to the power grid, storage batteries, wind and solar generators, CHP (concentrated water supply), and energy-consuming equipment in the wastewater treatment plant; the thermal pipeline is connected to the CHP, thermal storage tank, and biogas digester; the gas pipeline is connected to the CHP, biogas digester, and gas network; and the wastewater, after treatment at the wastewater treatment plant, is reused via water pipelines.

[0370] 2) The method of this invention optimizes the operation of a wastewater treatment plant:

[0371] 2.1) Input basic data

[0372] Input the basic parameters of the wastewater treatment plant, including: time-of-use electricity purchase price, time-of-use electricity sales price, gas price, wastewater load, irrigation water load, irrigation water price, secondary discharge revenue, tertiary discharge revenue, industrial miscellaneous water load, industrial miscellaneous water price, and wind and solar power output.

[0373] The time-of-use electricity purchase price and time-of-use electricity sale price are given in Table 1; the gas price, irrigation water price, secondary emission revenue, tertiary emission revenue, and industrial miscellaneous water price are given in Table 2; the wastewater load, irrigation water load, and industrial miscellaneous water load are given in Table 3.

[0374] Table 1 Time-of-use electricity prices

[0375]

[0376] Table 2 Costs and Benefits

[0377] Irrigation water price 0.1 cent / m 3 ]] Secondary emission benefits 0.01 yuan / m 3 ]] Gas purchase price 1.5 units / m 3 ]] Gas price 1.0 m 3 ]] Level 3 emission benefits 0.09 yuan / m 3 ]] Industrial miscellaneous water price 0.5 cents / m 3 ]]

[0378] Table 3 Water Load During the Scheduling Cycle

[0379] Time period Sewage load / m 3 ]] <![CDATA[Irrigation water load / m 3 > <![CDATA[Industrial miscellaneous water load / m 3 > 0 1500 85.40 10 1 1360 70.55 0 2 1356 87.68 10 3 1360 109.59 10 4 1320 70.55 20 5 1300 109.36 180 6 1260 109.36 70 7 1220 90.02 60 8 1280 119.43 50 9 1276 161.34 50 10 1362 264.56 90 11 1450 432.22 90 12 1540 514.01 20 13 1520 546.81 20 14 1480 538.38 30 15 1530 513.99 30 16 1510 408.48 20 17 1450 324.36 20 18 1420 204.00 70 19 1430 163.48 40 20 1426 149.56 60 21 1460 135.89 60 22 1480 94.28 0 23 1490 114.83 10

[0380] 2.2) Establish and solve a model of a wastewater treatment plant for wastewater reuse.

[0381] Based on the unit models, objective functions and constraints of the wastewater treatment plant listed above, equations (1)-(8) and (10)-(11) are piecewise linearized and then solved using the CPLEX solver. The operating cost error and solution time under different number of segments are obtained, as shown in Table 4.

[0382] Table 4. Operating cost error and solution time under different number of segments.

[0383] Number of segments Total cost / yuan relative error Solution time / s 5 1198.7 0.016％ 50 10 1198.6 0.0083％ 169 15 1198.5 / 891

[0384] 2.3) Experimental Results

[0385] Three operating modes were proposed for a wastewater treatment plant to compare and verify the effectiveness and superiority of the method of this invention. Scenario 1: Wastewater reuse is considered. Scenario 2: Wastewater reuse is not considered. Scenario 3: No clear water tank, secondary storage tank, or equalization tank components are configured, and the biogas temperature is constant.

[0386] (a) Comparison of operating costs

[0387] Table 5 shows the operating costs and total operating costs of the wastewater treatment plant under three scenarios.

[0388] Table 5 Operating Costs in Different Scenarios

[0389]

[0390] A comprehensive comparison reveals that Scenario 1 has higher electricity transaction costs than Scenario 2 due to the need for water reuse, resulting in higher water sales revenue by sacrificing less electricity costs. Scenario 3, lacking components such as water storage tanks, cannot reduce load during periods of high electricity prices, leading to even higher electricity transaction costs. Scenario 1 has the lowest overall operating cost compared to the other scenarios, highlighting the effectiveness and economy of this invention.

[0391] (b) Comparison of operating status of major equipment units

[0392] As attached Figure 4 Appendix Figure 5 As shown, in Scenario 3, due to the lack of components such as a water storage tank, load reduction is impossible during periods of high electricity prices, and the treated water volume is consistent with the sewage load. In Scenarios 1 and 2, due to lower wind and solar turbine output and lower electricity prices between 6:00 and 9:00, the sewage treatment plant purchases electricity to minimize power consumption and battery discharge, resulting in less secondary treated water. Between 12:00 and 17:00, due to lower electricity prices and higher irrigation demand, more secondary treated water is needed, and increased electricity purchases are required to store energy in the batteries to cope with peak electricity prices. Since tertiary treatment is more energy-intensive, it is mainly performed during off-peak electricity prices. In Scenario 1, due to water demand, tertiary water treatment is required during periods of flat electricity prices. In Scenario 2, since water reuse is not considered, tertiary treatment is not performed during periods of high electricity prices. (See attached image) Figure 6 As shown, scenarios 1 and 2 use higher temperatures to produce more biogas for sale when electricity prices are low, while maintaining lower temperatures and using more biogas for power generation when electricity prices are high. At 20:00, due to the low volume of water in the secondary treatment, the temperature needs to be increased to increase biogas production. Therefore, this invention fully leverages the flexibility of wastewater treatment plants to stabilize the load and perform peak shaving and valley filling, improving economic efficiency and load stability.

Claims

1. A method for optimizing the operation of a wastewater treatment plant considering wastewater reuse, characterized in that, Includes the following steps; 1) Obtain the basic parameters of the wastewater treatment plant; 2) Based on the basic parameters of the wastewater treatment plant, model the equipment units of the wastewater treatment plant to obtain the equipment unit model of the wastewater treatment plant; 3) Based on the wastewater treatment plant equipment unit model, establish an optimized operation model for the wastewater treatment plant that considers wastewater reuse; 4) Solve the optimal operation model of the wastewater treatment plant that considers wastewater reuse to obtain the optimal operation scheme of the wastewater treatment plant; The wastewater treatment plant equipment unit model includes a treatment unit model, a sludge-to-biogas production model, a CHP unit model, and an energy storage device model. The treatment unit model includes a primary wastewater treatment unit model, a secondary wastewater treatment unit model, and an advanced wastewater treatment model. The model for the primary wastewater treatment unit is shown below: P t,clar =c s Q t H t / 1000th (1) H t =aQ t 2 +bQ t r+cr 2 (2) In the formula, the subscript t indicates time t; P t,clar Let be the power of the cleaning pump at time t; η be the efficiency of the cleaning pump; Q t γ is the wastewater flow velocity entering the equalization tank at time t; s Specific gravity of wastewater; H t Let t be the head of the cleaning pump; r be the relative speed of the cleaning pump; and a, b, and c be empirical coefficients for the pump head curve. The model of a secondary wastewater treatment unit is shown below: In the formula, P t,Aer R is the blower power at time t; R is the air gas constant; T in η is the inlet temperature of the fan; B P represents the mechanical efficiency of the blower. a Atmospheric pressure; P t,stat P is the static pressure at the outlet of the blower diffuser. t,dyn For dynamic pressure; Q t,air M is the air mass flow rate; air The molecular mass of air; Among them, dynamic pressure P t,dyn Air mass flow rate Q t,air They are shown below: P t,dyn =(Q t,air / A dif ) 2 k p (4) In the formula, A dif The diffuser cross-sectional area; coefficient k p =275N s 2 / m 4 ;K La This is the standard oxygen transfer efficiency. This refers to the mass of oxygen per unit mass of air. Standard oxygen transfer rate; Standard oxygen transfer rate As shown below: m t,BOD =Q t,2 (BOD t,in -BOD t,out )ConB (7)m t,TKN =Q t,2 (TKN t,in -TKN t,out )ConN (8) In the formula, m t,BOD and m t,TKN The oxygen demand for oxidation and nitrification in the aeration tank are represented by β; β is the mass of oxygen per unit mass of air; C T and C T 0 At temperature T and reference temperature T, respectively. 0 Oxygen saturation concentration in freshwater; C d α is the dissolved oxygen concentration; θ is the oxygen transfer ratio in the wastewater; θ is a constant; BOD t,in and BOD t,out The BOD concentration of the influent and effluent of the wastewater treatment plant; TKN t,in and TKN t,out TKN concentration in the influent and effluent of the wastewater treatment plant; ConN is the oxygen ratio required for TKN oxidation; ConB is the oxygen ratio required for BOD oxidation; Q t,2 The flow rate for secondary treatment wastewater; The advanced wastewater treatment model is shown below: P t,3 =η3V t,3 (9) In the formula, η3 is the volume coefficient of wastewater treated per unit of electrical energy in the tertiary treatment stage; V t,3 P represents the volume of water entering the clear water tank after three stages of treatment at time t. t,3 The power consumption of the third-level processing at time t.

2. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that, The basic parameters of the wastewater treatment plant include time-of-use electricity purchase price, time-of-use electricity sales price, gas price, wastewater load, irrigation water load, irrigation water price, secondary discharge revenue, tertiary discharge revenue, industrial miscellaneous water load, and industrial miscellaneous water price.

3. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that, The sludge-to-biogas model includes equations for calculating biogas production, heat loss from the digester wall, and heat energy required for heating the sludge. The equation for calculating biogas production is shown below: In the formula, the subscript t indicates time t; m sl,t Let β be the sludge mass at time t; wsl p represents the sludge coefficient after wastewater has settled and settled. t,BG Let be the amount of biogas produced at time t; Reference temperature T 0 The sludge biogas production coefficient under the specified conditions; f t (T dig T represents the fermentation temperature T in the biogas digester at time t, indicating the anaerobic digestion process. dig Biogas production rate; f t (T 0 ρ represents the biogas production rate of the biogas digester at a reference temperature T0 at time t; wsl The average density of the wastewater after it has been left to stand and settle. Among them, the gas production rate f t (T dig ) and fermentation temperature T dig The relationship is as follows: f t (T dig )=m(T dig -T0) 2 +n (11) In the formula, m and n are the coefficients in the quadratic expression; The equations for calculating heat loss from the digester wall and the equations for calculating the heat energy required for sludge heating are as follows: Heat loss H from the digester wall t,loss The heat energy required for heating sludge (H) t,sludge for: In the formula, H t,loss H t,sludge These represent the heat loss from the digester wall and the heat energy required for heating the sludge, respectively; cp sludge T represents the specific heat capacity of sludge. t,air and T t,soil The air and soil temperatures were measured at time t, respectively; k air and k soil These are the heat transfer coefficients of air and soil, respectively; T so A represents the average influent sludge temperature. sup and A base These are the lateral area and base area of ​​the digester, respectively.

4. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that, The CHP unit model is shown below: P t,CHP_G =p t,gas L gas η CHP,e (13) H t,CHP =p t,gas L gas η CHP,h (14) In the formula, P t,CHP_G H represents the total power generation of CHP at time t; t,CHP p is the thermal power of CHP at time t; t,gas L represents the biogas flow rate consumed by CHP at time t. gas η is the calorific value of biogas. CHP,e and η CHP,h The figures represent the electrical and thermal efficiencies of CHP, respectively.

5. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that, The energy storage device model includes a battery model and a phase change thermal storage tank model; The battery model is shown below: In the formula, E t,bat and E t-Δt,bat The battery charge stored at time t and time t-Δt are respectively; Δt is time; P t,bat_cha and P t,bat_dis These are the charging and discharging power, respectively. These are the upper and lower limits of charging power; The upper and lower limits of discharge power; 0-1 variable I t,cha To represent the state variable of charging, I t,cha =1 indicates charging, I t,cha =0 indicates no charging; 0-1 variable I t,dis To represent the state variable of discharge, I t,dis =1 indicates discharge, I t,dis =0 indicates no discharge; η cha and η dis These refer to the charging and discharging efficiency of the battery, respectively. and These represent the upper and lower limits of the battery's energy storage capacity; E t,bat E represents the battery's energy storage capacity at time t. 0,bat and E T’,bat represents the initial and final values ​​of the battery within the scheduling cycle; T' represents the total number of time periods in a scheduling cycle. The phase change thermal storage tank model is shown below: In the formula, H t,bat and H t-Δt,bat The phase change thermal storage tanks store heat at time t and t-Δt, respectively; H t,bat_cha and H t,bat_dis These are the heat storage and heat release capacities, respectively. These are the upper and lower limits of thermal storage capacity; The upper and lower limits of heat release power; 0-1 variable I t,hcha It is a state variable used to represent thermal storage, I t,hcha =1 indicates thermal storage, I t,hcha =0 indicates no heat storage; 0-1 variable I t,hdis It is a state variable used to represent heat release, I t,hdis =1 indicates heat release, I t,hdis =0 indicates no heat release; η hcha and η hdis These refer to the heat storage and heat release efficiencies of the phase change thermal storage tank, respectively. and These represent the upper and lower limits of the thermal storage capacity of the phase change thermal storage tank; H t,bat H represents the thermal storage capacity of the phase change thermal storage tank at time t. 0,bat and H T’,bat These represent the initial and final values ​​of the phase change thermal storage tank within the scheduling cycle.

6. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that, The objective function of the optimized operation model for a wastewater treatment plant considering wastewater reuse is shown below: In the formula, f t,gas For gas network transaction costs; f t,gird For grid transaction costs; f t,W For revenue from water sales; f t,en For environmental benefits; Among them, the gas network transaction cost f t,gas , power grid transaction costs f t,gird Water sales revenue f t,W Environmental benefits f t,en They are shown below: In the formula, c t,gird and c gas These represent the time-of-use electricity price and gas price at time t, respectively; P t ,gird and P t , gas represents the interaction quantities with the power grid and gas grid at time t, respectively; c W2 and c W3 These are the secondary and tertiary water pricing systems, respectively; Q t , I and Q t , D These represent the secondary and tertiary water demands at time t, respectively; K en2 and K en3 These are the conversion factors for secondary and tertiary emissions, respectively; Q t,en2 Q represents the flow rate of water discharged after secondary treatment at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

7. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that, The constraints of the optimized operation model of a wastewater treatment plant considering wastewater reuse include electrical power balance constraints, gas balance constraints, thermal power balance constraints, secondary water treatment balance constraints, tertiary water treatment balance constraints, upper and lower limits of CHP output constraints, equalization tank constraints, secondary storage tank constraints, and clear water tank constraints. The power balance constraints are as follows: P t,wind +P t,CHP_G +P t,gird +P t,bat_dis +P t,PV =P t,bat_cha +P t,clar +P t,Aer +P t,3 (19) In the formula, P t,PV P represents the power generation capacity of the photovoltaic unit. t,wind P represents the power generation capacity of the wind turbine generator. t,Aer P is the blower power at time t; t,CHP_G P represents the total power generation of CHP at time t. t ,gird is the interaction quantity with the power grid at time t; P t,bat_cha and P t,bat_dis These represent charging and discharging power, respectively; P t,clar P represents the power of the cleaning pump at time t. t,3 The power consumption of the third-level processing at time t; The gas balance constraints are as follows: p t,BG -p t,gas =P t,gas (20) In the formula, p t,gas p is the biogas flow rate consumed by CHP at time t; t,BG P represents the amount of biogas produced at time t. t gas represents the amount of interaction with the gas network at time t; The thermal power balance constraints are shown below: H t,CHP +H t,bat_dis =H t,loss +H t,sludge +H t,bat_cha (21) In the formula, H t,CHP H represents the thermal power of CHP at time t; t,bat_cha and H t,bat_dis These are the heat storage and heat release powers, respectively; H t,loss H t,sludge These are the heat loss from the digester wall and the heat energy required for heating the sludge, respectively. The secondary water treatment balance constraints are shown below: Q t,2 =α2Q t,se2 (22) In the formula, Q t,se2 αt is the flow rate after secondary water treatment at time t; α2 is the secondary water treatment flow rate ratio; Q t,2 Let t be the secondary treated wastewater flow rate. The tertiary water treatment balance constraints are shown below: Q t,3 =α3Q t,th3 (23) In the formula, Q t,th3 α is the flow rate after tertiary water treatment at time t; α3 is the tertiary water treatment flow rate ratio; Q t,3 Let t be the flow rate of the tertiary treatment wastewater. The upper and lower limits of CHP output are constrained as follows: In the formula, and These are the upper and lower limits of CHP's electrical power output; and These represent the upper and lower limits of CHP thermal power output; P t,CHP and Q t,CHP Let be the electrical power and thermal power of CHP at time t, respectively. The constraints of the regulating pool are as follows: In the formula, R t,1 and R t-1,1 Let be the water storage capacity of the regulating tank at time t and time t-1; R represents the maximum water storage capacity of the equalization tank. 0,1 and R T,1 These are the initial and final values ​​within the regulating pool scheduling cycle, respectively; Q t Let t be the flow rate of wastewater entering the equalization tank. The constraints of the secondary reservoir are as follows: In the formula, R t,2 and R t-1,2 Let be the water storage capacity of the secondary reservoir at time t and time t-1; R is the maximum water storage capacity of the secondary reservoir. 0,2 and R T,2 These are the initial and final values ​​within the scheduling cycle of the secondary reservoir; Q t , I Q represents the secondary water demand at time t; t,en2 Let t be the flow rate of water discharged after secondary treatment; Clear water pool constraints: In the formula, R t,3 and R t-1,3 Let be the water volume stored in the clear water tank at time t and time t-1; R is the maximum water storage capacity of the clear water tank. 0,3 and R T,3 These are the beginning and end values ​​within the pool cleaning scheduling cycle, respectively; Q t , D Q represents the tertiary water demand at time t; t,en3 Let t be the water flow rate discharged after three stages of treatment.

8. The optimized operation method for a wastewater treatment plant considering wastewater reuse according to claim 1, characterized in that: Tools for solving optimal operation models of wastewater treatment plants that consider wastewater reuse include CPLEX.

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