Recycling Network Research Articles

Environmental Impacts of Plastic Materials Flow Minimisation Using Data-Driven Pinch Method

Plastics recycling, as a subclass of material recovery and recycling, features extensive and intensive properties. The intensive properties can be used to define a recyclability criterion and to classify the plastic materials for a symbiotic system (industrial, municipal and commercial) into recyclability categories, where the materials with higher recyclability can be either recycled/reused within the same category or cascaded and made available to categories with lower recyclability. The potential surplus waste materials of lowest-grade recyclability would be destined for waste treatment and disposal, while the potential deficit of materials in the highest-grade recyclability category would have to be fulfilled by supplying fresh plastic material produced from primary raw materials. The current contribution takes this problem formulation as a basis to optimise the plastics recycling of industrial symbiotic systems. It defines a Plastic Material Cascade Diagram and an associated set of Supply-Demand Composite Curves, identifying the recycling bottleneck – a Pinch Point limiting the rate of recycling and determining the most efficient material recycling network design. A case study is formulated to illustrate the usefulness of the new concept in reducing the consumption of raw materials and final waste.

Optimised design of concrete recycling networks: The case of North Rhine-Westphalia.

In Germany, construction and demolition waste is either landfilled or used for roadworks after being treated in recycling plants. However, recycled concrete aggregates from building demolition can be reused for the construction of new buildings, which allows to close the material loop of concrete. The aim of this study is to develop a decision support system (DSS) in order to investigate the economic impacts and consequences of recycling concrete from building demolition in a closed loop material cycle. To do so, we propose a bi-objective mixed-integer linear optimisation model that provides information on the number and location of installed sorting screens and defines the material flows within a comprehensive regional recycling network covering all processes from building demolition to construction of new buildings. While the economic objective function minimises the total costs of the recycling network, the circularity objective function minimises the amount of primary natural aggregates required for concrete manufacturing. We apply our optimisation model to the German federal state of North Rhine-Westphalia. Results show that under current conditions the manufacturing of concrete with recycled concrete aggregates is economically viable predominantly in areas without local supplies of natural aggregates. In addition, analysis of the trade-offs between the two objectives as well as recommendations on the design of political regulations and economic instruments to foster such recycling networks are presented.

Location-Routing Optimization with Renting Social Vehicles in a Two-Stage E-Waste Recycling Network

E-waste recycling has been a hot topic in recent years. The low efficiency and high-operation cost of recycling make it more important to build perfect e-waste recycling networks. To hedge against the limitation of vehicle resources being often neglected in existing research, we propose a mixed integer linear programming model of e-waste recycling by renting idle social vehicles. In the model, both decisions made on the location selection of recycling sites and vehicle routings satisfying all of the demand nodes over the network within time windows are required to minimize the total operating cost. An improved genetic algorithm and heuristic algorithm are designed to solve the model, and numerical experiments are produced to demonstrate the effectiveness of the proposed model and algorithms.

Reverse Logistics Network Design and Simulation for Automatic Teller Machines Based on Carbon Emission and Economic Benefits: A Study of the Anhui Province ATMs Industry

In recent years, mobile payments have gradually replaced cash payments, resulting in a gradual decline in the number of automatic teller machines (ATMs) demanded by banks. Through investigation and analysis, we determine four means to deal with decommissioned ATMs, and construct thereafter an ATM reverse logistics (RL_ATMs) network model, which includes suppliers, producers, warehouses, operators, maintenance centers, collection and inspection centers, disposal centers, remanufacturing centers, and recycling centers. This model is further expressed as a mixed integer linear programming (MILP) model. Given that an ATM recycling network has planned and batched characteristics, a percentage diversion method is proposed to transform a real multi-cycle problem to a single-cycle problem. The RL_ATMs network constructed in this study presents the two forms of ATMs, functional modules and the entire machine. We used the actual situations of the related companies and enterprises in Anhui Province and its surrounding areas, as well as major banks’ ATMs, as bases in using the LINGO software to solve the proposed MILP model with the objective function of minimizing costs and environmental emissions, and obtain the relevant companies’ launch operations. Lastly, we analyzed the relationship between coefficients in the percentage diversion method and calculation results, cost, and carbon emissions. Accordingly, we find that the number of remanufacturing and maintenance centers has no evident impact on the objective function, transportation costs account for a large proportion of the total cost, and emissions tax is small.

Modelling nonlinear dynamics of interacting tipping elements on complex networks: the PyCascades package

Tipping elements occur in various systems such as in socio-economics, ecology and the climate system. In many cases, the individual tipping elements are not independent of each other, but they interact across scales in time and space. To model systems of interacting tipping elements, we here introduce the PyCascades open source software package for studying interacting tipping elements (https://doi.org/10.5281/zenodo.4153102). PyCascades is an object-oriented and easily extendable package written in the programming language Python. It allows for investigating under which conditions potentially dangerous cascades can emerge between interacting dynamical systems, with a focus on tipping elements. With PyCascades it is possible to use different types of tipping elements such as double-fold and Hopf types and interactions between them. PyCascades can be applied to arbitrary complex network structures and has recently been extended to stochastic dynamical systems. This paper provides an overview of the functionality of PyCascades by introducing the basic concepts and the methodology behind it. In the end, three examples are discussed, showing three different applications of the software package. First, the moisture recycling network of the Amazon rainforest is investigated. Second, a model of interacting Earth system tipping elements is discussed. And third, the PyCascades modelling framework is applied to a global trade network.

Total Site Material Recycling Network Design and Headers Targeting Framework with Minimal Cross-Plant Source Transfer

Proper resources recycle or reuse planning helps the industrial sites to reduce reliance on raw resources. There are a lot of previous researches that had applied the Pinch Analysis on the resources recycling problem. However, there is not much work completed on targeting the materials headers or mains from the sources of the plants. This work extends the Material Recovery Pinch Diagram to provide an insightful yet straightforward approach to targeting the material headers/mains with minimum fresh resource consumption (e.g. water, hydrogen or CO2) with single quality. The flowrates and the concentration of the exchanged streams in the material headers, as well as the minimum number of headers, can be targeted using a Pinch-based strategy, which can be applied at either process or Total Site scale. This study also proposes a novel algorithm to minimise the cross-plant material source transfer for the Total Site material network with header/mains design while ensuring the overall minimum fresh resource target is satisfied. A Source Transfer Diagram is proposed to identify optimal reuse opportunities of the purged sources from individual plants. A case study is used to demonstrate the proposed framework, comparing results obtained using direct integration and centralised headers. The benefits of this framework are two-fold. It provides the minimum resource consumption rates for the overall network, and it also enables the network and mains/header design through graphical visualisation, which is a non-linear problem. The graphical interface allows users to explore different source mixing options from individual plants while ensuring the number of headers, resource consumptions, and cross-plant source transfer are minimal.

Cascaded Design of Desalination Systems: A Graphical Approach

A graphical technique to design staged desalination systems is introduced in this work by utilizing the concept of composite curves. Material recycle networks (MRNs), which are very popular graphic...

Routing Optimisation of Urban Medical Waste Recycling Network considering Differentiated Collection Strategy and Time Windows

The increasing gap between medical waste production and disposal stresses the urgency of further development of urban medical waste recycling. This paper investigates an integrated optimisation problem in urban medical waste recycling network. It combines the vehicle routing problem of medical facilities with different requirements and the collection problem of clinics’ medical waste to the affiliated hospital. To solve this problem, a compact mixed-integer linear programming model is proposed, which takes account of the differentiated collection strategy and time windows. Since the medical waste recycling operates according to a two-day pattern, the periodic collection plan is also embedded in the model. Moreover, we develop a particle swarm optimisation (PSO) solution approach for problem-solving. Numerical experiments are also conducted to access the solution efficiency of the proposed algorithm, which can obtain a good solution in solving large-scale problem instances within a reasonable computation time. Based on the results, some managerial implications can be recommended for the third-party recycling company.

Urban Informatics in Sustainable Waste Management: A Spatial Analysis of Korea’s Informal Recycling Networks

Large-scale informal recycling networks often emerge among developing economies in response to the challenges of modern urban waste accumulation. South Korea, despite its highly industrialized, developed economy, still maintains an extensive informal recycling sector made up of networks of local junk shops and individual waste pickers. As cities’ large data sources have become more widely available, the use of urban informatics in sustainable smart waste management has become more widespread. In this paper, we use geographic information system (GIS) analysis in order to uncover patterns within Korea’s informal recycling system, looking at the relationship between population demographics, waste levels, and urban planning with the prevalence of junk shops across Korea. We then interviewed junk shop owners, urban planning researchers, and government officials in order to better understand the factors that led to the coexistence of the country’s informal and formal systems of waste management and how junk shops have changed their operations over time in response to recent developments in cities’ urban fabrics. We conclude by giving suggestions for how the usage of urban informatics could increase the efficiency and sustainability of the country’s waste management systems, while also discussing the possible pitfalls of using such existing datasets for future policy decisions.

Dual closed-loop chemical recycling of synthetic polymers by intrinsically reconfigurable poly(disulfides)

<h2>Summary</h2> The excessive use of plastics has led to severe global problems involving environmental, energy, and health issues and demands for sustainable and recyclable alternatives. Toward circular plastics, the development of efficient chemical recycling methods without loss of properties or allowing reprocessing into new materials offer tremendous opportunities. Here, we report an intrinsically recyclable and reconfigurable poly(disulfide) polymer using a natural small molecule, thioctic acid (TA), as the feedstock. Taking advantage of its dynamic covalent ring-opening polymerization, this material enables a dual closed-loop chemical recycling network among TA monomers and two kinds of polymer products, including self-healing elastomers and mechanically robust ionic films. Mild and complete depolymerization into monomers in diluted alkaline aqueous solution is achieved with yields of recovered monomers up to 86%. The polymer materials can be repeatedly recycled and reused with reconfigurable polymer composition and tunable mechanical properties offering prospects for sustainable functional plastics.

Constructed Governance as Solution to Conflicts in E-Waste Recycling Networks

Electronic waste (e-waste) has become an increasingly pressing problem worldwide because of the increase in the volume of waste, without a corresponding increase in the recycling rate. E-waste recycling models show a low percentage of reuse, at around 17.4% in the world, 11% in Latin America, and 3% in São Paulo City, Brazil. The sources of conflicts relating to e-waste recycling networks are diverse, including asymmetries of objectives, knowledge, ethical values, and culture of sustainability, which indicates the need for a system of regulatory mechanisms. The article’s main proposition is that constructed governance, which is a collective process involving many actors, could be an alternative to e-waste recycling management. The city of São Paulo was chosen to be analyzed. Using an abductive methodology, the data analysis shows a fragmented network, with conflicts of interest among commercial and sustainability objectives, an absence of legal knowledge, and increases in the incorrect disposal of waste. However, initiatives in small groups in Brazil, which can be considered as examples of constructed governance, show a better volume of waste and the transportation of waste material to the right destination. The authors argue that constructed governance could be an efficient tool for e-waste recycling management systems. Besides, the article offers a matrix of indicators that can be used by both researchers and recycling managers.

Research on Optimization of NEV Power Battery Recycling Network

With the increasing number of new energy vehicles (NEV), the NEV industry is facing a situation of large amounts of retired power battery. In this study, first, the relevant research of the power battery recycling mode is sort out. And this paper proposes a four-level power battery recycling network, which includes nodes such as collection warehouse, storage warehouse, transfer hub, echelon utilization enterprise, etc.Then, a Mixed-Integer Non-Linear Programming model is proposed to minimize the cost of the network.

Heterogeneous fleet recyclables collection routing optimization in a two-echelon collaborative reverse logistics network from circular economic and environmental perspective

In recent years, production and consumption activities carried out in accordance with the “take-make-dispose” process have caused environmental damage and resource waste. Reverse logistics based on the concept of “sustainable development and circular economy” has gained public attention, including the recycling and reuse of recyclable wastes. In order to explore the impact of recyclable wastes transportation on cost, environment and resources, this paper focuses on a vehicle routing problem considering electric heterogeneous fleet for a two-echelon recycling network, recycling stations and recycling centers. With the goal of minimizing the total cost, a recycling heterogeneous fleet electric vehicle routing model with time windows is established under the consideration of vehicle load constraints, vehicle type constraints on the weight of loaded recyclable wastes and customer's allowable service time constraints. For carbon emissions reduction and environment protection, vehicles used in recycling stations are designated as electric vehicles. Then, a hybrid genetic algorithm with a large-scale neighborhood search algorithm is proposed. Finally, numerical experiments are conducted on vehicle types in recycling stations, and the computational results show the use of heterogeneous fleets could reduce costs. By analyzing the relationship between customer service time and total cost, the best service time rule could be obtained in the case of customer satisfaction. Meanwhile, by analyzing the relationship between the number and the loading capacity of electric vehicles in recycling stations and total cost, the best number and the loading capacity of electric vehicles could be obtained. This heterogeneous fleet recyclables collection routing model can greatly support the construction of recycling centers and the planning of recycling tasks, and provide a basis for recycling companies to deal with the relationship between economy, environment and resources.

Inclusive recycling movements: a green deep democracy from below.

This paper examines the multiple strategies articulated by grassroots recycler networks to bring about socioenvironmental change. The paper shows how these networks are an emblematic case of grassroots governmentality, whereby urban poor communities contribute to building more inclusive environmental regimes by developing technologies of power more typical of the powerful. These technologies include enumeration, with its resulting self-knowledge; the production of discourses and rationalities of social inclusion and environmental sustainability; and engagement in open and diverse alliances, at times with actors holding apparently antagonistic interests. The paper also reveals how recycling networks are a representative case of deep and green democracy. It is deep democracy, as grassroots networks strive to gain deep and true representativeness in their territories. It is green democracy, as it illustrates alternative pathways to environmental governance that is not limited to state and global organizations, but that also includes a range of control techniques emanating from the communities themselves.

Using the maximal covering location problem to design a sustainable recycling network

Recycling networks are essential to achieve sustainability in supply chains. Moreover, the design of recycling networks commonly focuses on reducing the costs of collecting a specific amount of end-of-life products or maximizing profit. We are interested in different scenarios with a non-profit approach where given an initial budget, our goal is to design a recycling network where the economic benefits from selling products for reuse or recycle are used to increase the network capacity so we maximize the amount of collected end-of-life products. We implement classic operations research techniques to represent the decision-making process with a maximal covering facility location problem that determines the following decisions: the number and location of capacitated collection centers with a limited-service area; the flow of end-of-life products from demand centers to collection centers and then, to capacitated recycling plants; and the amount of collected products sold to the secondary market. We design a mixed-integer linear formulation for our optimization problem, which can be solved with commercial solvers in short computational times for most of the large instances considered in our experimental stage. Numerical results on a case study in Brazil show that our optimization approach is a handy tool to design a recycling network and identify recycling plants with high low-usage rates.

Pinch Approach for Targeting in Multi-Contaminant Material Recycle/Reuse Network

Sophisticated approaches have been proposed to reduce material utilities such as water and hydrogen by designing resource allocation networks. For resource targeting, graphical methods have been developed for single quality material recycle/reuse. Up to now, systematic approaches to targeting fresh resources in a multi-contaminant material recycling network ahead of the detailed design are not readily available. This work presents a rigorous resource targeting procedure in the domain of multiple constraints (e.g. multi-contaminants). The problem is formulated as a resource-allocation superstructure model and modified to determine the model characteristics and obtain the optimal solution. These conditions are then transformed into a table and graphical forms to identify the minimum resource target. By inferring from the mathematical formulations, multiple cascades with individual contaminant/quality have to be analysed sequentially. The main issues are the identification of the proper assignment of material sinks or sources as well as their ranking into each cascade. An example is solved to illustrate the accuracy and applicability of the method. The method also provides insights into the problem as it could identify the limiting constraints for individual sinks.

A Nearest Neighbor Algorithm to Optimize Recycling Networks

This article analyses the processes of collecting used non-returnable packaging to improve the recycling of material. A collection system is proposed by applying a profitable visit algorithm based on the widely-known Nearest Neighbor Algorithm. A comparative study is performed to achieve a higher volume of recycled material while decreasing the cost of collection. The proposed algorithm shows a much better performance than the reference. The developed algorithm was evaluated in a real scenario and confirmed by a simulation runs. Savings in material sourcing processes can be achieved in real operations. The proposed algorithm shows some advantage.

A comparative study on end-of-life vehicles network design

This paper investigates the current research in the field of the end-of-life vehicles (ELV) recycling network. The optimisation of the location of a network facilities in forward logistics in the automotive industry has received a lot of attention for many years but the reverse logistics for ELVs has been a subject of investigations since the beginning of 21st century. ELV recycling network design gained in popularity after the European Union and other countries like Japan, South Korea and recently China introduced legal obligations to organize a collecting or recycling network for used vehicles. When regulations are introduced, there is a need for a systemic solution to the problem, especially since the obligation to create a collection network is often accompanied by requirements related to its accessibility for vehicle owners or efficiency of operation. With the growing scope of legal regulations, companies or organisations responsible for the network are forced to redesign the existing recycling infrastructure in a given area so that it meets specific requirements. Initially, the most important criterion was network availability. Currently, the same importance is attached to economic, environmental and social aspects in order to meet the sustainability criteria. In this paper, forty one peer-reviewed published studies focused on network design were classified. Its main purpose is to provide an extensive review of state-of-the-art research published in the period 2000-2019. The scope of the review is limited to network design problems including facility location and flow allocation problems. Only papers that present mathematical models are considered. Studies on the ELV network design are classified based on: type of supply chain, type of network, optimisation problem, type of facilities, modelling technique, single/multi objectivity, objective function, period of time, solution approach and scope of implementation. The final part of the paper includes discussion of the methodology of the reviewed studies and some recommendations for future research area.

Environmental change and the informal plastic recycling networks of Kolkata

This article introduces plastic recycling networks in Kolkata, India, as a case to illustrate the contradictory entanglement of economic and environmental change in urban informal contexts of the Global South. In light of the prevailing environmental critique of informal plastic recycling in India, this article discusses plastic recyclers’ environmental impact and contribution as well as the potential to enhance the environmental and economic performance of their business. Network and chain approaches in the emerging field of Environmental Economic Geography are combined with the notion of social metabolism to conceptualize the entanglement of environmental and economic processes as well as socio‐environmental inequalities entailed in recycling networks. The analysis reveals the impact that the heterogeneity and fluctuation of plastic waste supply has on the economic organization of recycling networks, giving rise to distinct forms of governance in its intermediate and down‐stream segments. Such an integrated perspective also serves to explain why environmental upgrading is hard to achieve under prevailing circumstances by plastic recyclers in Kolkata. Based on an assessment of the social and political conditions of informality under which plastic recyclers operate, the adoption of common assumptions about ecological modernization imbuing parts of Environmental Economic Geography is called into question.

Stable recycling networks under the Extended Producer Responsibility

A recently emerging concept, Extended Producer Responsibility (EPR), is being adopted by the government in more and more countries and regions. It shifts the burden of proper disposal of end-of-life consumer products from (local) governments to the producers that bring the products to the market. To comply with governments’ EPR-type legislation, producers form coalitions to have their products recycled in a more efficient way. In this paper, we study how two important determinants of recycling costs, fixed recycling costs and material-stream heterogeneity, influence producers’ recycling network (structure of producers’ recycling coalitions). On one hand, large fixed recycling costs make the coalitions typically larger, due to the economies of scale. On the other hand, large coalitions generate typically more heterogeneous material streams, which increase the variable recycling costs due to additional separation and disassembly efforts. This paper discusses two currently existing scenarios: one exists prior to EPR-type legislation (referred to as the Disparate Problem, or DP) and the other is motivated by EPR-type legislation (referred to as the Endogenous Problem, or EP). In DP, the recycling of end-of-life products is not the responsibility of any producer but the government. Therefore, the recycling network is determined to minimize the total recycling cost, which also maximizes the social welfare, while the outputs are determined by producers without concerns about recycling. In EP, producers who compete in a horizontally differentiated primary market may also collaborate at the same time to organize proper disposal of their products. As each producer is only interested in maximizing its own payoff and there may exist conflict of interests, we use the game-theoretical methodology to analyze the endogenous process of coalition-formation. We find structural differences in these two scenarios and conclude by discussing implications for social welfare of imposing tax or subsidy.