An optimization method for anaerobic treatment of food waste considering carbon emissions

Abstract

The present invention discloses a method for optimizing anaerobic treatment of food waste in consideration of carbon emissions, comprising step 1: pre-treating food waste and a substrate, mixing the food waste and the substrate in a certain proportion for anaerobic co-digestion reaction; step 2: determining the goal of anaerobic treatment of food waste, with minimizing carbon emissions as the main goal, and maximizing total profits and maximizing job opportunities as secondary goals; step 3: setting constraints, which include reaction material constraints, product constraints, food waste treatment constraints and inventory constraints; step 4: solving the goal according to the goal set in step 2 and the constraints in step 3 to obtain the optimal solution, that is, selecting the type of substrate and determining its quantity and the total quantity of food waste transported back from a secondary food waste collection point, thereby achieving a balance between economic benefits and carbon emissions.

Description

Technical Field

[0001] The present invention belongs to the technical field of food waste treatment, and in particular relates to an anaerobic treatment optimization method for food waste considering carbon emissions. Background Art

[0002] The accelerated development of the fast food economy and population growth have led to the generation of a large amount of food waste. Food waste is a valuable resource with great potential. Scientific use and treatment of food waste can promote sustainable development. The rise of the storm of reforms to "reduce, recycle and harmlessly treat" waste has led to the vigorous development of waste treatment technology.

[0003] Anaerobic monodigestion of food waste using microorganisms to produce biogas consumes less energy, causes less pollution and odor than other treatment methods such as incineration, landfill and composting. However, the low carbon-nitrogen ratio and high biodegradability of food waste can lead to rapid acidification during the process and the accumulation of volatile fatty acids, which in turn inhibit the digestion process. Therefore, other substrates are now commonly used for anaerobic co-digestion with food waste to solve the problems of high organic load, rapid acidification and toxic inhibitors. At present, there are still some shortcomings in the anaerobic treatment of food waste: the treatment volume of food waste and anaerobic co-digestion is uncertain, which makes it impossible for managers to accurately arrange procurement and storage plans; the treatment of food waste lacks comprehensive consideration of the impact of carbon emissions on the entire system, including carbon emissions from the entire link of pretreatment, treatment, transportation and storage. Summary of the invention

[0004] The purpose of the present invention is to provide a method for optimizing anaerobic treatment of food waste taking carbon emissions into consideration, which method can help a food waste treatment system determine the optimal mixed treatment scheme for multi-dimensional objectives, obtain different effects of different food wastes and different mixing ratios on the optimal system decision, and control the carbon emissions of the entire system to be minimal and the economic benefits to be maximized.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A method for optimizing anaerobic treatment of food waste considering carbon emissions comprises the following steps:

[0007] Step 1: pre-treating food waste and substrate to remove impurities and waste; mixing food waste and substrate in a certain ratio for anaerobic co-digestion reaction; products produced during the anaerobic co-digestion reaction include biogas, biodiesel and fertilizer;

[0008] Step 2: Determine the goals of anaerobic treatment of food waste, with minimizing carbon emissions as the primary goal and maximizing total profits and job opportunities as secondary goals, as follows:

[0009]

[0010] Where f1 is profit, which is the difference between total revenue and total cost; SR is total revenue, which is composed of sales revenue of all products including biodiesel, biogas and fertilizer; FC is fixed cost, VC is variable cost, and fixed cost and variable cost constitute total cost; f2 is carbon emission, E pre-treatment is the carbon emission during the pretreatment process, E treatment is the carbon emission during the anaerobic co-digestion reaction, E transportation is the carbon emission during transportation, E inventory is the carbon emission of inventory; f3 is job opportunities, which include the number of social service jobs in the process of food waste treatment; H pre-treatment is the number of jobs in the preprocessing process, H treatment is the number of jobs in the anaerobic co-digestion reaction process, E transportation The number of jobs in the transportation process.

[0011] Step 3: Set constraints, including reaction material constraints, product constraints, food waste disposal constraints and inventory constraints;

[0012] Step 4: Solve the goal to obtain the optimal solution based on the goal set in step 2 and the constraints in step 3, that is, select the type of substrate and determine its quantity and the total amount of food waste transported back from the secondary food waste collection point, so as to achieve a balance between economic benefits and carbon emissions.

[0013] Furthermore, the carbon emissions during the pretreatment process is the specific carbon emission associated with food waste and substrate during pretreatment; Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, i is the number of waste treatment plants, and m is the type of substrate.

[0014] Furthermore, the carbon emissions during the anaerobic co-digestion reaction are The specific carbon emissions from the treatment of a mixture of food waste and substrate in an anaerobic co-digestion reaction are: is the amount of food waste and substrate after mixing, and θ is the reaction ratio of the processed mixture.

[0015] Furthermore, the carbon emissions during the transportation process CE1, CE2 and CE3 are the unit carbon emissions related to food waste, substrate and product during transportation, respectively; S ij is the distance from the garbage treatment plant to the food waste collection site; Q ijThe amount of food waste transported from food waste collection sites to waste treatment plants; S ih The distance from the waste treatment plant to the bottom source site; S is the amount of substrate m purchased by the waste treatment plant from the substrate source site; iu is the distance from the waste treatment plant to the product demand site; LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu is the amount of fertilizer purchased by the product demand site from the waste treatment plant, j is the number of collection sites, h is the substrate purchase source site, m is the substrate type, and u is the product demand site.

[0016] Furthermore, the carbon emissions of the inventory IE1 and IE m is the unit carbon emission associated with the stockpiled food waste and substrate; Q ij The amount of food waste transported from food waste collection sites to waste treatment plants; is the quantity of substrate m purchased by the waste treatment plant from the substrate source site; Z i is the amount of pre-processed food waste, is the amount of pretreated substrate.

[0017] Furthermore, the reaction material constraint refers to the constraint between food waste and substrate. Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, ω mθ :v mθ is the ratio of mixed food waste and substrate, m is the substrate type, θ represents the reaction ratio of the treated mixture, WP is the amount of water required for the co-elimination anaerobic reaction process, The amount of food waste and substrate after mixing; the amount of food waste and substrate processed cannot exceed the amount transported to the waste treatment plant 0≤Z i ≤∑ j Q ij ,

[0018] Furthermore, trapezoidal fuzzy numbers are used to deal with uncertain parameters. and and are the total amount of food waste and substrate collected, respectively;

[0019]

[0020] In the formula, a is the determination The minimum value of b is determined The maximum value of c and d is The most likely value, e, is determined The minimum value of f is determined The maximum value of g and h is most likely value;

[0021] By combining the trapezoidal fuzzy number with the parameter π that describes the attitude of the decision maker towards the parameter, some equivalent parameters can be constructed and converted into them.

[0022] Furthermore, the product sales constraint means that all products (biodiesel, fertilizer and biogas) can be sold, and the sales volume is equal to the production volume. and is the specific biodiesel and fertilizer yield of food waste and substrate mixed at reaction ratio θ at waste treatment plant i; The amount of food waste mixed with substrate; LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu the amount of fertilizer purchased from the waste treatment plant for the product demand site;

[0023] The purchase volume of product demand stations does not exceed the sales volume of waste treatment plants LT iu and SY iu Biodiesel and fertilizer sales routes determined for waste treatment plants, LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu the amount of fertilizer purchased from the waste treatment plant for the product demand site;

[0024] Sales volume must meet or even exceed market demand GD、LD u , SD u Indicates market demand for biogas, biodiesel and fertilizers; is the unit biogas production of food waste and substrate mixed at reaction ratio θ at waste treatment plant i.

[0025] Furthermore, the food waste processing constraint refers to the maximum processing capacity of food waste (mixed substrate), VO i is the total number of fermentation agents, X max is the total number of fermentation agents in the waste treatment plant;

[0026] The total amount of dry matter (substances other than water) in the starter should be between [α,,β,], Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, Indicates the amount of food waste mixed with substrate.

[0027] Furthermore, the inventory constraint means that the unfermented food waste and substrate cannot exceed the maximum inventory of the waste treatment plant. are the maximum stock levels for food waste and substrate, respectively.

[0028] The present invention constructs a multi-objective mixed integer linear programming model with carbon emission minimization as the main goal, total profit maximization and job opportunity maximization as the secondary goals, to optimize the food waste and other substrate mixed treatment system based on anaerobic co-digestion and ester exchange technology; the present invention considers the influence of different substrates, different treatment ratios and different objective preference scenarios on system decision-making, and also considers the uncertainty of substrate source quantity. By constructing trapezoidal fuzzy numbers to solve, it can help food waste system managers determine the best mixed treatment scheme for multi-dimensional goals, and obtain different food wastes and different mixing ratios. The optimal system decision has different effects, and the carbon emissions of the entire system are controlled to be minimum. The present invention can determine whether the design and arrangement of the system balance economic, environmental and social goals at the same time, and at the same time provides a pre-purchase and storage plan, so that the control of carbon emissions is more comprehensive, scientific and reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the optimization process of the present invention.

[0030] Figure 2 It is a schematic diagram of the anaerobic treatment process of food waste of the present invention. DETAILED DESCRIPTION

[0031] like Figure 1 , Figure 2 As shown, this embodiment provides an optimization method for anaerobic treatment of food waste considering carbon emissions, comprising the following steps:

[0032] Step 1: Pre-treat food waste and substrate to remove other impurities and waste mixed in food waste and substrate; mix food waste and substrate in a certain proportion to ensure a suitable anaerobic co-digestion reaction. The biogas produced during the anaerobic co-digestion reaction is purified and injected into the municipal natural gas pipeline, the residue is treated and used to produce fertilizer, the lipid substances in the leachate are filtered and biodiesel is produced through ester exchange reaction, and the remaining sewage is purified and discharged; the whole process ensures the effective use and treatment of food waste. Since the anaerobic co-digestion of food waste and other substrates greatly improves production efficiency, the system-based operation goal is to select the type of substrate and determine its quantity and the total amount of food waste transported back from the secondary collection point of food waste.

[0033] Since the total amount of food waste and substrate is variable and uncertain, managers need to determine the uncertainty in advance in order to arrange appropriate treatment plans according to the reaction requirements, that is, the specific amount of food waste and substrate for mixed treatment, while untreated food waste and other substrates are temporarily stored. At the same time, in order to protect the environment and achieve the dual carbon goals, the total amount of carbon emissions is strictly controlled, and carbon emissions in each link are fully considered: garbage pretreatment, treatment, transportation of substrates, food waste, products, and storage of substrates and food waste, with the main goal of minimizing system carbon emissions. Then balance with economic and social goals as secondary goals.

[0034] The model proposed in this embodiment provides an effective tool for food waste treatment system managers because it can determine whether the design and arrangement of the system balance economic, environmental and social goals at the same time, while providing a forward-looking procurement and warehousing plan, making the control of carbon emissions more comprehensive, scientific and reasonable.

[0035] Step 2: Determine the goal of anaerobic treatment of food waste. In this embodiment, the primary goal is to minimize carbon emissions, and the secondary goals are to maximize total profits and maximize job opportunities. The details are as follows:

[0036]

[0037] Where f1 is profit, which is the difference between total revenue and total cost; SR is total revenue, which is composed of sales revenue of all products including biodiesel, biogas and fertilizer; FC is fixed cost, VC is variable cost, and fixed cost and variable cost constitute total cost; f2 is carbon emission, E pre-treatment is the carbon emission during the pretreatment process, E treatment is the carbon emission during the anaerobic co-digestion reaction, E transportation is the carbon emission during transportation, E inventory is the carbon emission of inventory; f3 is job opportunities, which include the number of social service jobs in the process of food waste treatment; H pre-treatment is the number of jobs in the preprocessing process, H treament is the number of workers in the anaerobic co-digestion reaction process, H transportation The number of jobs in the transportation process.

[0038] Carbon emissions during pretreatment is the specific carbon emission associated with food waste and substrate during pretreatment; Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, i is the number of waste treatment plants, and m is the type of substrate.

[0039] Carbon emissions during anaerobic co-digestion The specific carbon emissions from the treatment of a mixture of food waste and substrate in an anaerobic co-digestion reaction are: is the amount of food waste and substrate after mixing, and θ is the reaction ratio of the processed mixture.

[0040] Carbon emissions during transportation CE1, CE2 and CE3 are the unit carbon emissions related to food waste, substrate and product during transportation, respectively; S ij is the distance from the garbage treatment plant to the food waste collection site; Q ij The amount of food waste transported from food waste collection sites to waste treatment plants; S ih The distance from the waste treatment plant to the bottom source site; S is the amount of substrate m purchased by the waste treatment plant from the substrate source site; iu is the distance from the waste treatment plant to the product demand site; LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu is the amount of fertilizer purchased by the product demand site from the waste treatment plant, j is the number of collection sites, h is the substrate purchase source site, m is the substrate type, and u is the product demand site.

[0041] Carbon emissions from stocks IE1 and IE m is the unit carbon emission associated with the stockpiled food waste and substrate; Q ij The amount of food waste transported from food waste collection sites to waste treatment plants; is the quantity of substrate m purchased by the waste treatment plant from the substrate source site; Z i is the amount of pre-processed food waste, is the amount of pretreated substrate.

[0042] Step 3: Set constraints to solve the target and obtain the optimal solution. The constraints include reaction material constraints, product constraints, food waste disposal constraints and inventory constraints.

[0043] Reaction mass constraints refer to the constraints between food waste and substrate Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, ω mθ :v mθ is the ratio of mixed food waste and substrate, m is the substrate type, θ represents the reaction ratio of the treated mixture, WP is the amount of water required for the co-elimination anaerobic reaction process, It is the amount of food waste mixed with substrate.

[0044] Food waste processed (Z i ) and substrate The amount of transportation cannot exceed the amount transported to the waste treatment plant 0≤Z i ≤∑ j Q ij ,

[0045] Due to the uncertainty of the reaction materials, this embodiment uses trapezoidal fuzzy numbers to deal with uncertain parameters and and are the total amount of food waste and substrate collected, respectively.

[0046]

[0047] In the formula, a is the determination The minimum value of b is determined The maximum value of c and d is The most likely value, e, is determined The minimum value of f is determined The maximum value of g and h is The most likely value.

[0048] By combining the trapezoidal fuzzy number with the parameter π that describes the decision maker's attitude towards the parameter, some equivalent parameters can be constructed and converted. The amount transported to the waste treatment plant cannot exceed the amount collected at the secondary recycling point, Y ij , Y ih For transportation route plan,

[0049] Product sales constraint: assume that all products (biodiesel, fertilizer and biogas) can be sold, and their sales volume is equal to production volume and is the specific biodiesel and fertilizer yield of food waste and substrate mixed at reaction ratio θ at waste treatment plant i; The amount of food waste mixed with substrate; LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu The quantity of fertilizer purchased from the waste treatment plant for the product demand site.

[0050] The purchase volume of product demand stations does not exceed the sales volume of waste treatment plants LY iu and SY iu Biodiesel and fertilizer sales routes determined for waste treatment plants, LQ iuThe quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu The quantity of fertilizer purchased from the waste treatment plant for the product demand site.

[0051] Sales volume must meet or even exceed market demand GD、LD u , SD u Indicates market demand for biogas, biodiesel and fertilizers; is the unit biogas production of food waste and substrate mixed at reaction ratio θ at waste treatment plant i.

[0052] Food waste treatment constraint refers to the maximum food waste (mixed substrate) treatment capacity. VO i is the total number of fermentation agents, X max is the total number of fermentation agents in the waste treatment plant. The total amount of dry matter (substances other than water) in the fermentation agent should be between [α,,β,], Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, Indicates the amount of food waste mixed with substrate.

[0053] The inventory constraint means that the unfermented food waste and substrate cannot exceed the maximum inventory of the waste treatment plant. MV i , are the maximum stock levels for food waste and substrate, respectively.

[0054] All variables must be non-negative And Y ij ={0,1},Y ih ={0,1},LY iu ={0,1},SY iu ={0,1}.

[0055] The above description is only a preferred implementation manner of the present invention, but the protection scope of the present invention is not limited thereto, and any modification and replacement based on the technical solution and inventive concept provided by the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing anaerobic treatment of food waste considering carbon emissions, characterized in that: The steps include: Step 1: pre-treating food waste and substrate to remove impurities and waste; mixing food waste and substrate in a certain ratio for anaerobic co-digestion reaction; products produced during the anaerobic co-digestion reaction include biogas, biodiesel and fertilizer; Step 2: Determine the goals of anaerobic treatment of food waste, with minimizing carbon emissions as the primary goal and maximizing total profits and job opportunities as secondary goals, as follows: Where f1 is profit, which is the difference between total revenue and total cost; SR is total revenue, which is composed of sales revenue of all products including biodiesel, biogas and fertilizer; FC is fixed cost, VC is variable cost, and fixed cost and variable cost constitute total cost; f2 is carbon emission, E pre-treatment is the carbon emission during the pretreatment process, E treatment is the carbon emission during the anaerobic co-digestion reaction, E transportation is the carbon emission during transportation, E inventory is the carbon emission of inventory; f3 is job opportunities, which include the number of social service jobs in the process of food waste treatment; H pre-treatment is the number of jobs in the preprocessing process, H treatment is the number of workers in the anaerobic co-digestion reaction process, H transportation The number of jobs in the transportation process; Step 3: Set constraints, including reaction material constraints, product constraints, food waste disposal constraints and inventory constraints; Step 4: Solve the target to obtain the optimal solution according to the target set in step 2 and the constraints in step 3, that is, select the type of substrate and determine its quantity and the total amount of food waste transported back from the secondary food waste collection point, so as to achieve a balance between economic benefits and carbon emissions; Wherein, the reaction material constraint refers to the constraint between food waste and substrate Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, ω mθ :v mθ is the ratio of mixed food waste and substrate, m is the substrate type, θ represents the reaction ratio of the treated mixture, WP is the amount of water required for the co-elimination anaerobic reaction process, The amount of food waste and substrate after mixing; the amount of food waste and substrate processed cannot exceed the amount transported to the waste treatment plant 0≤Z i ≤∑ j Q ij , The product constraint means that biodiesel, fertilizer and biogas can all be sold, and the sales volume is equal to the production volume. and is the specific biodiesel and fertilizer yield of food waste and substrate mixed at reaction ratio θ at waste treatment plant i; The amount of food waste mixed with substrate; LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu the amount of fertilizer purchased from the waste treatment plant for the product demand site; The purchase volume of product demand stations does not exceed the sales volume of waste treatment plants LY iu and SY iu Biodiesel and fertilizer sales routes determined for waste treatment plants, LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu the amount of fertilizer purchased from the waste treatment plant for the product demand site; Sales volume must meet or even exceed market demand GD、LD u , SD u Indicates market demand for biogas, biodiesel and fertilizers; is the specific biogas production of food waste and substrate mixed at reaction ratio θ at waste treatment plant i; The food waste processing constraint refers to the maximum food waste processing capacity. VO i is the total number of fermentation agents, X max is the total number of fermentation agents in the waste treatment plant; The total amount of dry matter in the starter should be between [α,β], Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, It indicates the amount of food waste and substrate after mixing; The inventory constraint means that the unfermented food waste and substrate cannot exceed the maximum inventory of the waste treatment plant. MV i , are the maximum stock levels for food waste and substrate, respectively.

2. The method for optimizing anaerobic treatment of food waste considering carbon emissions according to claim 1, characterized in that: Carbon emissions from the pretreatment process is the specific carbon emission associated with food waste and substrate during pretreatment; Z i is the amount of pre-processed food waste, is the amount of pretreated substrate, i is the number of waste treatment plants, and m is the type of substrate.

3. The method for optimizing anaerobic treatment of food waste considering carbon emissions according to claim 1, characterized in that: Carbon emissions during the anaerobic co-digestion reaction The specific carbon emissions from the treatment of a mixture of food waste and substrate in an anaerobic co-digestion reaction are: is the amount of food waste and substrate after mixing, and θ is the reaction ratio of the processed mixture.

4. The method for optimizing anaerobic treatment of food waste considering carbon emissions according to claim 1, characterized in that: Carbon emissions during transportation CE1, CE2, and CE3 are the unit carbon emissions associated with food waste, substrate, and products during transportation, respectively; S ij is the distance from the garbage treatment plant to the food waste collection site; Q ij The amount of food waste transported from food waste collection sites to waste treatment plants; S ih The distance from the waste treatment plant to the bottom source site; S is the amount of substrate m purchased by the waste treatment plant from the substrate source site; iu is the distance from the waste treatment plant to the product demand site; LQ iu The quantity of biodiesel purchased from the waste treatment plant for the product demand site; SQ iu is the amount of fertilizer purchased by the product demand site from the waste treatment plant, j is the number of collection sites, h is the substrate purchase source site, m is the substrate type, and u is the product demand site.

5. The method for optimizing anaerobic treatment of food waste considering carbon emissions according to claim 1, characterized in that: Carbon emissions from the stock IE1 and IE m is the unit carbon emission associated with the stockpiled food waste and substrate; Q ij The amount of food waste transported from food waste collection sites to waste treatment plants; is the quantity of substrate m purchased by the waste treatment plant from the substrate source site; Z i is the amount of pre-processed food waste, is the amount of pretreated substrate.

6. The method for optimizing anaerobic treatment of food waste considering carbon emissions according to claim 1, characterized in that: Using trapezoidal fuzzy numbers to deal with uncertain parameters and and are the total amount of food waste and substrate collected, respectively; In the formula, a is the determination The minimum value of b is determined The maximum value of c and d is The most likely value, e, is determined The minimum value of f is determined The maximum value of g and h is most likely value; By combining the trapezoidal fuzzy number with the parameter π that describes the decision maker's attitude towards the parameter, an equivalent parameter is constructed and converted into and

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