Organization of Chemical Production Based on the Principles of Green Chemistry: Waste Recycling and Resource Chains in the Production of Rubber Products

Abstract

A new look at the concept of green chemistry from the side of the laws of production organization allows for the development of organizational solutions for achieving environmental friendliness of chemical–technological processes without capital-intensive modernization of production lines. The uniqueness of chemical production, unlike most industries, is the maximum possibility of organizing a closed resource–waste production cycle. The purpose of the article is to develop solutions for organizing chemical production based on the principles of green chemistry with an emphasis on waste recycling and resource chains using the example of rubber product production. Analysis and critical assessment of publications and literary sources showed a shortage of research on organizational tools for creating green production systems with minimal resource losses and maximum product yield. Interpretation of the laws of production organization in the projection of “green” chemistry made it possible to identify six vectors for creating sustainable production with a high strength of interrelation between the laws of production organization and the principles of green chemistry. The solutions obtained in most cases are aimed at increasing the closed nature of production and organizing circular resource chains. Using the example of rubber tire and cover production, trends of waste recycling prevalence (69%) were revealed compared to their disposal (31%). Based on artificial neural networks, a model of usefully used waste in circular resource chains was built, where three variables act as factors of sustainable production: the mass of waste returned to its own production cycle; the mass of waste returned to the production cycle of another enterprise, and the mass of waste sent for storage or disposal at landfills. The highest rate of beneficially used waste in circular resource chains is achieved in the third scenario, which prioritizes reintegrating waste back into the production cycle (57.5%). The transition from one scenario to another does not result in a polar shift in this rate, which instead varies within a range of 50–58%. The proposed solutions can be used by enterprises when choosing engineering directions and tools based on the synthesis of “green chemistry” concepts and production organization laws. Prospects for the development of the topic lie in the development of the methodology for organizing environmental engineering in the proposed directions and implementation tools as well as research into the technology of organizing closed low-waste production processes.

1. Introduction

The uniqueness of chemical industries, unlike most industries, is the maximum possibility of organizing a closed resource–waste cycle of production. D.I. Mendeleev believed that there is no waste in chemistry, but unused raw materials [1]. If we talk about the traditional ecology of chemical production, then, first of all, we mean the methods of purification of process waste or localization of pollutants in the external environment.

Green chemistry goes one step further and advocates complete or partial modification of chemical technologies to reduce waste generation and pollutant emissions. Green chemistry revises the approach to chemical technologies and involves a shift from the utilization of pollutants to the creation of highly environmentally friendly chemical production processes. For example, the number of production steps can be reduced, and thus the amount of energy used can be reduced.

Green chemistry is an extension of the concept of sustainable development in the field of chemistry [2,3]. The value of the 12 basic principles of green chemistry lies not only in the proposed approaches to optimize the chemical technologies used. A deeper understanding of the principles of green chemistry allows, in some cases, the development of organizational solutions that allow the achievement of high environmental friendliness of chemical–technological processes without capital-intensive modernization of production lines [4,5].

At the same time, in studying scientific works in the field of green chemistry, it should be noted that most of the developments are related to the development of chemical technologies and processes, and the sphere of organization of green chemistry production remains poorly studied to date. At the same time, not all principles of sustainable production can be observed as a result of the development or improvement of chemical technology. The organization of the main, auxiliary, and supporting processes of production allows for the connection of knowledge and labor with the material elements of production so as to ensure the production of high-quality green products on the basis of rational, careful use of resources and means of production.

In turn, the careful use of resources can be achieved by organizing circular resource chains. The return of waste into the production cycle provides an opportunity to convert chemical production waste into energy or precursor substances for other processes.

The aim of the article is to develop solutions for the organization of sustainable chemical production on the principles of green chemistry with a focus on waste recycling and the organization of resource chains, using the example of rubber product production.

2. Literary Review

2.1. Environmental Sustainability of Production

Sustainable production in scientific and practical literature is often mentioned in the context of the concept of sustainable development, carbon sustainability, and the ESG agenda. Accordingly, most management and methodological researchers define sustainable production as the creation of products with minimal negative environmental, social, and economic impacts. Han D. from Nankai University and co-authors interpret sustainable production from the perspective of an organization’s ability to maintain stability, adapt, and grow in a low-carbon transformation [6]. The authors identify the positive impact of carbon sustainability on improving the ESG performance of industrial enterprises. Ma Y. from Nanjing University of Science and Technology, with a research team, identified the impact of ESG criteria on the green performance of new quality, particularly performance in green innovation [7]. The possibility of integrating sustainability and ESG criteria into the process of evaluating suppliers of industrial raw materials is studied by scientists of Opole University of Technology, Rudnik K., Chwastyk A., and Pisz I. In their opinion, the application of ESG criteria increases the value of the decision-making system by adapting to the current trends in green supply chain management [8].

Researchers and practitioners of engineering and technology profile study the environmental sustainability of production from the position of the application of specific technologies, designs, and information systems. The developments are mostly focused on the creation of a closed production cycle based on new technologies and the use of secondary raw materials in homogeneous and related spheres of the economy and industry. The most frequent publications are devoted to the application of waste in the construction industry. For example, Ghazzawi S. and co-authors proposed the use of olive by-products as an environmentally friendly secondary raw material in the production of cement mortar [9], Indraratna B. and co-authors described the reuse of glass waste as a construction material for transportation infrastructure [10], and the possibility of using marble crumbs and powder from glass waste as binding materials in the production of mortar was studied by a scientific team led by Alemu M.Y. [11].

Many works are devoted to the use of biowaste as an alternative fuel: Brás I. and his team proposed the use of woody biomass for heat production, Dossow M. and co-authors assessed the potential of the sugar industry for the production of environmentally friendly aviation fuel based on the conversion of biomass into liquid products [12], and Wulyapash W. and his team studied the possibility of producing fuel from seafood processing waste and plastic waste from landfills [13].

The above suggests that the main principle of sustainable production in the works of scientists and practitioners describes waste recycling and circular supply chains. However, there are few works on organizational tools for creating green production systems with minimum resource losses and maximum product yield.

2.2. Green Chemistry

Green chemistry, as a progressive scientific direction, is oriented towards waste-free production. It denies the utilization of waste items and excludes the very possibility of their formation. This direction is quite new; it originated and has been developing since the 1990s of the last century. A significant contribution to the development of green chemistry was made by scientists P.T. Anastas and J.S. Warner [2,4]. Following the principles of green chemistry allows for the reduction in production costs by eliminating the stages of waste utilization and purification of harmful emissions.

At the initial stage of the development of green chemistry, there are many different versions among scientists regarding its essence and development, which is reflected in scientific publications. International scientific journals publish articles mainly in the framework of new developments of chemical synthesis technologies: environmentally friendly process of chemical recycling and reuse of polymers [14], sustainable catalysis for green chemistry [15], functional biomedical polymeric materials [16], industrial biotechnology for pharmacology [17], etc. Russian publishers similarly place scientific papers on the achievements of chemical technology in, for example, the production of construction materials [18], household chemistry and cosmetics [19,20], high-molecular compounds [21], and mining [22].

The list of directions can be continued indefinitely, but there is an opinion that most of the developments with a mention of green chemistry are related to the broader concept of the modern evolutionary chemistry of L. Pauling [23]. Green chemistry represents a narrower specific orientation, outlined in 12 principles of design and organization of chemical processes by a method that limits the use and formation of harmful substances and waste.

At the same time, an interesting development of green chemistry is the adaptation of the 12 principles to the laws of production organization. The organization of the main, auxiliary, and supporting processes of production allows for the connection of knowledge and labor with the material elements of production so as to ensure the production of high-quality green products on the basis of rational, careful use of resources and means of production.

2.3. Production Organization

Production organization as a science is a set of principles, concepts, and methods that ensure the optimal combination of factors and human labor, on the basis of which products are created. The industry of developed countries, which has moved far ahead, pays special attention to the organization and logistics of production. The reason for this is the possibility of increasing the resource efficiency of production and its environmental sustainability not only by, for example, changing chemical technology, but also by reorganizing the business processes of the enterprise.

The issues of organization and logistics of production concern various spheres of activity. In particular, scientists study the planning of human–machine–logistic resources in production [24], the design of sustainable supply chain management processes [25,26], sustainability risk management in the processes of product control, labeling, packaging, and storage [27], sustainable closed-loop production, and product life cycle organization [28].

The concepts and tools of sustainable production organization, such as lean production for elimination of resource losses [29,30], best available technologies [31], system of organized network recycling of resources [32], waste outsourcing technologies [33], energy audit and analysis [34], introduction of automated flow lines, product life cycle assessment (LCA) [35], and others are actively studied. The above-mentioned and other methods and tools can increase the sustainability of production facilities, including in conjunction with the directions of green chemistry.

3. Materials and Methods

3.1. Green Chemistry Metric E-Factor

Roger A. Sheldon’s green chemistry metric, the E-factor, is the ratio of the mass of by-products (waste) generated by a chemical process to the mass of the target product:

$$E={\displaystyle \raisebox{1ex}{$W_w$}\!\left/ \!\raisebox{-1ex}{$W_p$}\right.}$$

(1)

where W_w is the mass of by-products (waste); W_p is the mass of the target product.

Depending on the type of production, the proposed threshold values vary from 0.1 in the production of petroleum products to 25 or more in the production of medicines. According to the literature sources, this criterion within the framework of one type of chemical production can objectively assess the change in the level of environmental friendliness of technological processes in dynamics, characterize the change in waste, and be of interest not only to process engineers and environmentalists, but also to economic services and logistics departments. In this case, the results of the assessment of green chemistry development can diagnose both optimization of chemical technologies and optimization of organizational solutions (lean production, automation of processes, reduction in production cycle, recycling, controlling, etc.).

Thus, the E-factor is of interest both for diagnosing the efficiency of chemical technologies and for organizational solutions. Further, this parameter is used as a basis for the development of criteria for the environmental friendliness of chemical production.

3.2. Methodology for Compiling the PL Adjacency Matrix

In order to determine the strength of the relationship between the law of production organization and the principle of green chemistry for the purpose of creating sustainable production, a method is proposed to build an adjacency matrix: “Laws of production organization (L)—principles of green chemistry (P)” (PL Matrix). The PL Matrix vertically represents the principles of green chemistry P1–P12, and horizontally—the laws of production organization L1–L6 (

Table 1. Layout of the adjacency matrix “Laws of production organization (L)—principles of green chemistry (P)” (PL Matrix) to determine the strength of the relationship between the law of production organization and the principle of green chemistry.

	PL Criterion Value				∑ PL	Power of PL
	L1	L2	…	L6
P1	[0,1]	[0,1]	…	[0,1]	∑ P1L = P1L1 + P1L2 + … + P1L6	PLmax/PLmed/PLmin
P2	[0,1]	[0,1]	…	[0,1]	∑ P2L = P2L1 + P2L2 + … + P2L6	PLmax/PLmed/PLmin
…	…	…	…	…	…
P12	[0,1]	[0,1]	…	[0,1]	∑ P12L = P12L1 + P12L2 + … + P12L6	PLmax/PLmed/PLmin

, Figure 1).

The PL criterion, named as “The strength of the relationship between the law of production organization and the principle of green chemistry for the purpose of creating sustainable production,” is introduced. The scale for determining the value of the PL criterion is conventionally adopted in the range [0,1], where 0 is the minimum strength and 1 is the maximum strength.

The PL amount is calculated by summing the points according to the laws of production:

$$\sum P_{n}L=P_n{L}_1+P_n{L}_2+P_n{L}_3+P_n{L}_4+P_n{L}_5+P_n{L}_6,\mathrm{where}\mathrm{n}=[1;12].$$

(2)

Determination of vectors of sustainable production engineering was carried out according to the total score of the PL criterion:

PL > 4.0—high strength of the relationship between the law of production organization and the principle of green chemistry for the purposes of creating sustainable production (PLmax);

3.5 < PL < 4.0—medium high strength of the relationship between the law of production organization and the principle of green chemistry for the purposes of creating sustainable production (PLmed);

PL < 3.5—low strength of the relationship between the law of production organization and the principle of green chemistry for the purposes of creating sustainable production (PLmin).

3.3. Method for Assessing the Significance of PL Criterion

The significance of the PL criterion was assessed on the basis of the expert method. Expert evaluation methods are used in situations where the selection, justification, and evaluation of decisions cannot be made on the basis of accurate calculations.

The decision was based on the opinions of six experts—representatives of environmental safety services of chemical enterprises and employees of government agencies in terms of management and monitoring of processes in industry and the ecosystem.

The expert selection procedure for the peer review included the following standard stages:

• Formulation of the expert review’s purpose and objectives.
• Definition of expert requirements: competency profile—environmental engineer, process engineer; experience—at least 10 years, highest qualification, proven experience in reengineering implementation.
• Formation of a base list of candidates: scientific publications, colleague recommendations, databases, authoritative organizations.
• Candidate assessment and selection: verifying candidate compliance with the criteria.
• Formation of the final expert group: determining the optimal number of experts to ensure representativeness and manageability.
• Checking the expert group’s reliability: assessing consensus of opinions using test questions, calculating the competence coefficient.

The assessments were obtained by the interview method on the basis of the developed regulations for collecting and analyzing expert assessments (the interview method involves a conversation with an expert according to the “question-answer” scheme). The experts’ expert assessments were developed on the basis of the method of preference vectors (selection of alternatives and determination of the most preferable one) and focal objects (method based on transferring the features of randomly selected analogs to the object under study). Further, the expertise of the received opinions and assessments of experts was carried out by the method of comparison of average scores (integral scores).

4. Results

4.1. Solutions for Organizing Sustainable Chemical Industries Based on the Principles of Green Chemistry

Production organization as a science is based on six basic principles or laws: synergy, self-preservation, development, information orderliness, unity of analysis and synthesis, composition, and proportionality. Observance of these laws in the organization of production allows the formation of an “ideal”, effectively functioning industrial object. When creating sustainable industries, following the laws of production organization is mandatory and important to achieve the maximum possible design goals and results.

Interpretation of the laws of production organization in the projection of “green” chemistry allows the adaptation of the system of laws to the principles of formation of sustainable industries (Figure 1).

The law of synergy says that the properties of a sustainable production system as a whole exceed the sum of the properties of its elements. For example, investing resources in the ecologization of production will significantly strengthen the potential of the production system. The law of self-preservation takes place when there is an impact on production of external or internal factors that lead to increasing uncertainty. To maintain the sustainability of the production system, the organization uses its potential by adopting green technologies. Throughout its life cycle, chemical production is continuously improving, increasing environmental sustainability, which is regulated on the basis of the law of development. The law of awareness and orderliness is necessary to reduce the uncertainty of the environmental parameters of production. In order to study environmental parameters and improve the validity of decisions on greening production, it is necessary to consider the object as a system and subject it to analysis and synthesis. Such a system approach, based on the law of unity of analysis and synthesis, allows us to make a deep analysis of the elements or subsystems of the production system, identify problem areas, and find effective solutions. Finally, the law of composition and proportionality says that it is necessary to take into account the composition of structural elements of production when carrying out environmental engineering.

Using the logical content method, let us consider which of the 12 principles of green chemistry can be observed and developed within the framework of the laws of production organization. As stated earlier, achieving sustainable production is possible by changing the approaches to the synthesis and technology of chemical products, methods of cleaning pollutants, and methods of production organization—the re-engineering of main, auxiliary, and service production processes.

To visualize the relationships, we used the adjacency matrix RL, where the principles of green chemistry P1–P12 are represented vertically, and the laws of production organization L1–L6 are represented horizontally (

Table 2. Adjacency matrix “Laws of Production Organization (L)—Principles of Green Chemistry (P)” (PL Matrix) to determine the strength of the relationship between the law of production organization and the principle of green chemistry for the purpose of creating sustainable production.

	PL Criterion Value						∑ PL	Power of PL
	L1	L2	L3	L4	L5	L6
P1	1.0	0.8	0.6	0.4	0.8	0.8	4.4	PLmax
P2	0.8	0.4	1.0	0.6	0.8	0.6	4.2	PLmax
P3	0.6	0.4	0.6	0.4	0.6	0.2	2.8	PLmin
P4	0.6	0.4	0.6	0.4	0.6	0.2	2.8	PLmin
P5	0.4	0.4	0.6	0.6	0.4	0.4	2.8	PLmin
P6	0.6	0.4	0.6	0.6	0.6	0.4	3.2	PLmin
P7	0.8	0.6	0.6	0.6	0.6	0.8	4.0	PLmax
P8	0.8	1.0	0.8	1.0	1.0	0.6	5.2	PLmax
P9	0.6	0.4	0.6	0.6	0.4	0.6	3.2	PLmin
P10	0.8	0.6	0.8	0.6	0.8	0.8	4.4	PLmax
P11	0.4	0.6	0.8	0.8	0.6	0.6	3.8	PLmed
P12	0.4	0.6	0.8	1.0	0.8	0.8	4.4	PLmax

).

We believe that it is reasonable to choose vectors of sustainable production creation with PL values > 4.0 (PLmax) or high strength of interrelation between the law of production organization and the principle of green chemistry. PLmax is observed for six items—principles of green chemistry:

P1 Loss and waste prevention (PL = 4.4);

P2 Renewable raw materials and materials (PL = 4.2);

P7 Use of room temperature and pressure (PL = 4.0);

P8 Process monitoring (PL = 5.2);

P10 Maximization of product yield (PL = 4.4);

P12 Safe process (PL = 4.4).

Certain laws of production organization can have a greater regulatory impact in the creation of sustainable production and give high development efficiency: PL criterion values > 0.8. The laws of production organization with PL criterion value < 0.8, with the same organizational efforts, will show a relatively lower environmental result.

Thus, the system of vectors of engineering of sustainable chemical production based on the principles of green chemistry will have the following form:

$$S=f\left(\begin{array}{c}\overline{B_1}=\left\{P_1{L}_1;P_1{L}_2;P_1{L}_5;P_1{L}_6\right\}\\ \overline{B_2}=\left\{P_2{L}_1;P_2{L}_3;P_2{L}_5\right\}\\ \overline{B_3}=\left\{P_7{L}_1;P_7{L}_6\right\}\\ \overline{B_4}=\left\{P_8{L}_1;P_8{L}_2;P_8{L}_3;P_8{L}_4;P_8{L}_5\right\}\\ \overline{B_5}=\left\{P_{10}{L}_1;P_{10}{L}_3;P_{10}{L}_5;P_{10}{L}_6\right\}\\ \overline{B_6}=\left\{P_{12}{L}_3;P_{12}{L}_4;P_{12}{L}_5;P_{12}{L}_6\right\}\end{array}\right)$$

(3)

where S is a system of vectors of engineering of sustainable chemical production.

B1, … B6—vectors of engineering with high strength of interrelation of the law of production organization and the principle of green chemistry.

The set includes synthesized vectors of the organization of sustainable productions, which, according to the results of logical and content analysis, have a high potential for the implementation of environmental projects.

The interpretation of the sign representation of engineering vectors (B1–B6) in the decisions on the organization of sustainable production is presented in Figure 2.

In order to control the parameters on the solutions of sustainable production organization B1–B6, it is necessary to monitor such indicators (relative indicators) as the following:

• Volume of losses of material resources in production chains relative to the normative value (B1);
• Share of by-products and waste products returned to the production cycle (B2);
• Consumption of fuel and energy resources per unit of production (B3);
• Duration of the production cycle relative to its critical path (B4);
• Consumption of material resources per unit of production (B5);
• Emissions into the atmosphere, discharges into water bodies, and solid waste per unit of production (B6).

The above indicators are logically consistent with the metric of “green” chemistry development—the E-factor, which is the ratio of the mass of by-products (waste) to the mass of the obtained target product.

An example of the practical application of vector B3 can be shown using a real industrial facility—a gas condensate stabilization unit at an oil refinery. Here, thermos ream integration was applied to optimize the heat exchange system through pinch analysis. The results revealed a pinch point for the technology in question of 24 °C. This can lead to a reduction in fuel consumption of up to 30%, which translates into savings of up to USD 3 million per year.

4.2. Priority on the Useful Use of Waste and Circular Resource Chains

In one way or another, all synthesized solutions for the organization of sustainable chemical production are aimed at increasing the closed-loop production and organization of circular resource chains [35]. The return of waste into the production cycle is possible both within their own enterprise and by transferring waste to third-party organizations for recycling purposes.

According to state statistics, in the primary production and in the process of recovery of rubber tires, tires, and other rubber products at Russian enterprises in 2024, more than 50 types of waste were generated (FKKO code 3 31 200 00 00 0) [36,37]. For the analysis, 48 waste items were selected where the volume of accumulated waste materials exceeded 1 ton per year. Of the 48 waste items, 33 were returned to the production cycle within their own enterprise or sold to other organizations for beneficial use. Accordingly, 15 types of waste were not sent for recycling, but were disposed of in landfills (Figure 3 and Figure 4).

Analysis of the list of 15 types of waste sent for storage or disposal in landfills shows the presence of such materials as the following:

• Paper packaging contaminated with reagents;
• Waste of contaminated polyethylene and ferrous metal containers;
• Waste of gaskets made of sheet rubber;
• Waste of cotton fabric during the manufacture of cord;
• Bag filters used in gas purification and others.

The listed types of waste have a potential for recycling into associated or other products, which is justified by the availability of appropriate technology and global practices. However, at this stage of production, the listed waste items are not utilized but sent to landfills. In general, statistics show that in developed countries, industrial waste is recycled almost completely, whereas in Russia, the share of the useful use of industrial waste is about 40%.

Waste returned to the production cycle is predominantly recycled within the framework of its own production, as well as sold to other enterprises for reuse. Many enterprises combine their own recycling and organization of external resource chains in various proportions.

In our own production, four types of waste are fully recycled, which make up 3.19% of the mass of all waste (

Table 3. Waste processed only in our own production (model “I recycle waste myself”).

Name of Waste from the Production of Rubber Tires, Covers, and Other Rubber Products	Share of Waste Returned to Production, %
waste rubber–bitumen products during their production	41.94
cuttings of textile fabric made of cotton and artificial fibers during the production of rubberized fabric products	35.12
waste spinning tow during the de-fibering of textiles during the production of rubberized fabric products	28.29
polyethylene trimmings and scraps in the production of rubber products	0.91

). These are mainly residues of bitumen–rubber mastic, textile samples in the production of rubber products. These waste items can be processed using the main equipment of the enterprise, which is the reason for their own use.

A combination of in-house recycling and waste sales to third parties in various proportions is observed for 17 types of waste, which is 92.84% of the volume of usefully used waste (

Table 4. Waste processed in own and third-party production (model “I process and sell waste myself”).

Name of Waste from the Production of Rubber Tires, Covers, and Other Rubber Products	Structure of the Mixed Model of Waste Recycling, %		Share of Waste Returned to Production, %
	Processed in Our Own Production	Recycled in Third-Party Production
waste rubber compounds for the production of automobile tires	74.35	25.65	74.20
cuttings of rubberized cord during the cutting of fabrics in the production of tires	47.56	52.44	60.44
vulcanized rubber waste in the production of automobile tires	4.90	95.10	53.59
waste rubber compounds from cleaning equipment for the production of rubber compounds	99.98	0.02	52.86
waste diaphragms during the production of automobile tires	48.93	51.07	52.72
waste unvulcanized rubber compounds for the production of automobile tires	9.55	90.45	46.86
waste carbon black in the form of dust during the production of rubber compounds	67.18	32.82	43.41
rubber–metal product rejects	4.68	95.32	35.43
cuttings of vulcanized rubber	23.70	76.30	27.58
dust from gas cleaning of the production of rubber compounds	56.12	43.88	24.55
waste carbon black during its preparation for the production of rubber compounds	88.25	11.75	20.18
dust (flour) rubber	96.03	3.97	19.05
waste rubberized fabric products during their production	74.98	25.02	18.02
waste from the preparation of bulk mineral materials for the production of rubber compounds	80.36	19.64	8.58
rubber–metal shavings in the manufacture of shafts with an elastomer coating	41.39	58.61	5.58
talc waste in the powdering of rubber compounds and rubber blanks	59.26	40.74	2.92
rubber waste from cleaning process equipment in the production of rubber tires	50.00	50.00	0.03

). Five types of waste are used at 50% or more of their mass: these are the readily recyclable waste of rubber mixtures and cord trimmings in the production of automobile tires. Less than 20% of waste from rubber–fabric products and rubber–metal shavings is returned to the production cycle, which is due to the more complex technology of their secondary use. The choice of in-house recycling or waste sales is also made by taking into account the availability of equipment and technology at the enterprise for the secondary use of materials. Mainly, rubber mixture waste without significant impurities is processed at in-house production facilities (more than 70%).

Twelve types of waste are sold for recycling to third-party organizations, which is 3.97% of the volume of usefully used waste (

Table 5. Waste processed only in third-party production (model “I sell waste”).

Name of Waste from the Production of Rubber Tires, Covers, and Other Rubber Products	Share of Waste Returned to Production, %
paper packaging laminated with polyethylene contaminated with bulk reagents for the manufacture of polymer-bound additives	100.00
waste from cleaning oleic acid storage tanks	64.88
waste of sidewalls of automobile tires and tires	51.97
waste from cleaning equipment for the manufacture of polymer-bound additives for the production of rubber products	50.00
paper packaging laminated with polyethylene contaminated with bulk reagents for the manufacture of polymer-bound additives	50.00
latex waste during the production of products from it	16.96
cuttings of rubber sheeting and defective rubber coatings in their production	13.46
gasket fabric that has lost its consumer properties during the storage of rubber products	12.32
waste from paper packaging contaminated with bulk materials for the production of rubber compounds	3.04
waste braided rubber shock-absorbing cords during their production	0.63
waste from cleaning of machines and equipment for the production of tires containing petroleum products of 15% or more	0.44
waste of rubber glue in the production of automobile tires	0.16

). Subject to sale on the side is the waste of contaminated paper packaging and gasket fabric, as well as the waste of latex and rubber shock-absorbing cords and the waste of rubber glue that requires special equipment.

The high level of natural resources in Russian industry has a somewhat restraining effect on the level of waste recycling. In this regard, the waste recycling industry is poorly developed both in organizational and technical terms and from an economic point of view. There are also administrative difficulties, consisting of the lack of a legislative base and state support.

4.3. Modeling the Dependence of the Waste Recycling Level on the Model of Waste Management Organization for Rubber Tires and Covers

In Russian industry, as in the industry of any country, a general model of waste management organization is formed under the influence of legislation and other factors [36]. The general model includes three priorities in a certain ratio: the first priority is for waste recycling in own production, the second priority is for waste recycling in third-party production, and the third priority is for waste storage and disposal. The task is to build a mathematical model of usefully used waste in circular resource chains. The data array covers 48 types of waste from the production of rubber tires, covers, and other rubber products.

For modeling, we use the method of creating mathematical models based on artificial neural networks. The fact that the problem is nonlinear is beyond doubt, which is why preference is given to neural networks [38,39,40]. Neural networks are capable of learning from examples when the type and structure of the relationships between input and output data are unknown, and of identifying hidden patterns [41,42].

Most classical regression models assume that the relationship between the features and the target variable can be easily transformed into a linear relationship using polynomial features. If the actual relationship resembles a spiral or a complex curve, regression will provide a rough approximation [43]. A neural network, thanks to its activation functions and multiple layers, is inherently capable of approximating a continuous function of any complexity. The network architecture automatically identifies and models complex interactions between multiple features in hidden layers [44].

At the input to the neural network, we accept the following variables:

• Dependent variable y is the specific weight of usefully used waste in circular resource chains;
• Independent variable x1 is the mass of waste returned to its own production cycle;
• Independent variable x2 is the mass of waste returned to the production cycle of another enterprise;
• Independent variable x3 is the mass of waste sent for storage or disposal at landfills.

To achieve a balance between overfitting and underfitting of the network, we split the dataset into subsamples in the ratio: training—70%, test—30%. We use a universal function approximator for regression models—a direct propagation neural network, MLP. We train the network based on the iterative numerical optimization algorithm BFGS. The resulting neural network with a training performance of 0.87 has a three-layer MLP 3-3-1 architecture with three hidden neurons, where each neuron of the first layer is connected to each neuron of the hidden layer. The activation functions of the hidden neurons and the output neuron are logistic. Synaptic weights for a more accurate approximation of the function y = f (x) are presented in the

Table 6. Coefficients characterizing connections (synapses) between variables of a neural network.

Connections MLP 3-3-1	Values of Scales MLP 3-3-1
x1 ⟶ hidden neuron 1	0.94160
x2 ⟶ hidden neuron 1	−0.33711
x3 ⟶ hidden neuron 1	−1.12569
x1 ⟶ hidden neuron 2	1.31538
x2 ⟶ hidden neuron 2	0.28686
x3 ⟶ hidden neuron 2	−1.95471
x1 ⟶ hidden neuron 3	0.27639
x2 ⟶ hidden neuron 3	0.28279
x3 ⟶ hidden neuron 3	−0.75149
input offset ⟶ hidden neuron 1	−0.06199
input offset ⟶ hidden neuron 2	−0.08930
input offset ⟶ hidden neuron 3	−0.14256
hidden neuron 1 ⟶ y	1.99508
hidden neuron 2 ⟶ y	0.12657
hidden neuron 3 ⟶ y	−0.96566
hidden offset ⟶ y	−0.22207

.

The adders of the input variables x1, x2, x3 and the synaptic weights t1, t2, t3, respectively, will have the following form:

$${\mathrm{t}}_1={0.94\mathrm{x}}_1+1.31{\mathrm{x}}_1+0.27{\mathrm{x}}_1-0.062=2.52{\mathrm{x}}_1-0.062;$$

$${\mathrm{t}}_2={-0.34\mathrm{x}}_2+0.29{\mathrm{x}}_2+0.28{\mathrm{x}}_2-0.089=0.23{\mathrm{x}}_2-0.089;$$

$${\mathrm{t}}_3={-1.12\mathrm{x}}_3-1.95{\mathrm{x}}_3-0.75{\mathrm{x}}_3-0.142=-3.82{\mathrm{x}}_3-0.142.$$

The activation function of hidden neurons transforms adders t1, t2, t3 into the output signal of the hidden layer neuron (σ1, σ2, σ3):

$$\sigma \left(x_1\right)=\mathrm{ }{\displaystyle \frac{1}{1+e^{2.52x_1+0.062}}};$$

$$\sigma \left(x_2\right)=\mathrm{ }{\displaystyle \frac{1}{1+e^{0.23x_2+0.089}}};$$

$$\sigma \left(x_3\right)=\mathrm{ }{\displaystyle \frac{1}{1+e^{3.82x_3+0.142}}}.$$

The adder of the output variable y and the synaptic weights t4 will have the following form:

$$t_4={\displaystyle \frac{1.99}{1+e^{2.52x_1+0.062}}}+{\displaystyle \frac{0.13}{1+e^{0.23x_2+0.089\mathrm{ }}}}-{\displaystyle \frac{0.96}{1+e^{3.82x_3+0.142\mathrm{ }}}}-0.22.$$

The activation function of the output neuron y or the model of usefully used waste in circular resource chains will have the following form:

$$y=\mathrm{ }{\displaystyle \frac{1}{1+e^{-\left(\frac{1.99}{1+e^{2.52x_1+0.062}}+\frac{0.13}{1+e^{0.23x_2+0.089\mathrm{ }}}-\frac{0.96}{1+e^{3.82x_3+0.142\mathrm{ }}}-0.22\right)}}}.$$

Based on the obtained model, the specific gravity of usefully used waste in circular resource chains was predicted (

Table 7. Forecasting the specific gravity of usefully used waste in circular resource chains based on the neural network model.

Scenarios for the Development of Models for Organizing Production and Waste Management	Share of Waste Returned to Own Production Cycle, Thousand Tons	Share of Waste Returned to the Production Cycle of Another Enterprise, Thousand Tons	Share of Waste Sent for Storage or Disposal at Landfills, Thousand Tons	Forecast: Share of Usefully Used Waste in Circular Resource Chains, %
	x1	x2	x3	y_(t)
scenario 1	0.250	0.350	0.400	50.841
scenario 2	0.333	0.333	0.333	53.454
scenario 3	0.450	0.350	0.200	57.489

). Three scenarios of waste production and turnover models were selected:

• Scenario 1—development of the model towards the priority of waste storage and disposal at landfills (ratio x1:x2:x3 = 0.25:0.35:0.40);
• Scenario 2—development of the model in equal ratios (ratio x1:x2:x3 = 0.33:0.33:0.33);
• Scenario 3—development of the model towards the priority of waste return to the production cycle (ratio x1:x2:x3 = 0.45:0.35:0.20).

The table shows that the transition from one scenario to another is not accompanied by a polar change in the specific gravity of usefully used waste, and the range of y_(t) values varies in the range of 50–58%. The ternary graph confirms the relative stability of the dependent variable when changing x1–x3 (Figure 5).

It is logical that the highest value of the specific weight of usefully used waste in circular resource chains during forecasting (y = 57.489) is obtained in the third scenario with the development of the model towards the priority of returning waste to the production cycle (ratio x1:x2:x3 = 0.45:0.35:0.20).

5. Conclusions

The study of models for organizing chemical production based on the principles of green chemistry allowed us to obtain the following scientific and practical results:

• Analysis and critical assessment of publications and literature sources related to the environmental sustainability of production showed an emphasis on waste recycling and circular resource chains. At the same time, there is a shortage of research on organizational tools for creating green production systems with minimal resource losses and maximum product yield. An interesting development of green chemistry is the adaptation of its principles to the laws of organizing the main, auxiliary, and supporting production processes for the purposes of producing environmentally friendly products. The concepts and tools of lean manufacturing, the best available technologies, an organized network resource recycling system, waste outsourcing technologies, energy audit and analysis, the introduction of flow-automated lines, product life cycle assessment, and others have high potential for creating sustainable production. The listed methods and tools can increase the sustainability of production, including in combination with green chemistry areas.
• Interpretation of the laws of production organization in the projection of “green” chemistry allowed the adaptation of the system of laws to the principles of the formation of sustainable production. It is shown which of the 12 principles of green chemistry can be observed and developed within the framework of the laws of production organization. To determine the strength of the relationship between the law of production organization and the principle of green chemistry for the purpose of creating sustainable production, the adjacency matrix “Laws of production organization (L)—principles of green chemistry (P)” (Matrix PL) is proposed. Six vectors of the creation of sustainable production with a high strength of relationship between the laws of production organization and the principles of green chemistry are identified:
  • P1 + (L1, L2, L5, L6) = B1 “Control of resource losses in production chains at all stages of the production life cycle”;
  • P2 + (L1, L3, L5) = B2 “Organization of maximum return of waste (secondary resources) to the production cycle”; P7 + (L1, L6) = B3 “Integration of thermal flows, automation of energy processes to optimize the consumption of thermal energy resources”;
  • P8 + (L1, L2, L3, L4, L5) = B4 “Control and optimization of production cycle time by closing processes and reducing intermediate stages”;
  • P10 + (L1, L3, L5, L6) = B5 “Control of the level of waste and resource intensity of products, increasing the closed nature of the production system (B5)”;
  • P12 + (L3, L4, L5, L6) = B6 “Automation of control of production parameters in order to minimize the impact on the environment”.
• The synthesized solutions for organizing sustainable chemical production are aimed at increasing the closed nature of production and organizing circular resource chains. Using the example of rubber tire and cover production, trends were identified in favor of waste recycling over disposal: 69% of waste was returned to the production cycle, 31% of waste was sent for storage and disposal at landfills. In 92% of cases, a mixed model of “I recycle and sell waste myself” is used: enterprises combine their own recycling and organization of external resource chains in varying proportions. A third of the waste (31%) sent for storage and disposal at landfills has a high recycling potential, but is not returned to the production cycle: contaminated paper packaging, polyethylene container waste, sheet rubber waste, cotton fabric waste, etc.
• A model of usefully used waste in circular resource chains was constructed using the method of creating mathematical models based on artificial neural networks. Since the vectors of sustainable chemical production organization B1-B6 are primarily aimed at increasing the closed nature of production and organizing circular resource chains, three variables act as factors of sustainable production: the mass of waste returned to the own production cycle; the mass of waste returned to the production cycle of another enterprise; and the mass of waste sent for storage or disposal at landfills. The specific gravity of usefully used waste was predicted for three scenarios of organizing production and waste turnover: Scenario 1—development of the model towards the priority of storage and disposal of waste at landfills; Scenario 2—development of the model in equal proportions; Scenario 3—development of the model towards the priority of returning waste to the production cycle. The highest value of the specific gravity of usefully used waste in circular resource chains is obtained in the third scenario with the development of the model towards the priority of returning waste to the production cycle (57.5%). It is shown that the transition from one scenario to another is not accompanied by a polar change in the specific gravity of usefully used waste, but varies in the range of 50–58%.

The proposed solutions can be used by enterprises when choosing directions and tools of engineering based on the synthesis of the concepts of “green chemistry” and the laws of production organization. The prospects for the development of the topic are the development of the methodology of organizing environmental engineering in the proposed directions and the tools of implementation, and research into the technology of organizing closed, low-waste production processes.