Document Type : Research Paper

Authors

• Mehdi Seifbarghy
• Shaghayegh Zangeneh

Department of Industrial Engineering, Faculty of Engineering, Alzahra University, Tehran, Iran

Abstract

The increasing volume of industrial waste and the environmental pressures caused by non-biodegradable products have highlighted the necessity of redesigning supply chains within the framework of a circular economy. Polyester carpets, as a high-consumption product with a short lifecycle, play a significant role in this challenge. This study presents a mixed-integer linear programming model for the design and optimization of a closed-loop supply chain in the Iranian polyester carpet industry. In the proposed model, forward and reverse flows are integrated across multiple levels, including raw material supply, production, distribution, collection of used products, refurbishment, and recycling. The objectives of the model are to minimize the total network costs and enhance environmental performance through the use of eco-friendly materials and clean technologies. To address the multi-objective nature of the problem, fuzzy programming and goal programming approaches are employed. The model is validated through a case study in the Iranian carpet industry using real-world data. The results show that the fuzzy programming approach provides much better environmental performance than other methods. The environmental index value in this method is equal to 259,658, which shows a significant improvement compared to the value of 54437 of the goal programming method. However, this improvement is naturally accompanied by an increase in the total network costs. Overall, the proposed model creates a favorable trade off between the total network costs and environmental goals.
Introduction
In recent years, increasing environmental concerns and the rapid growth of industrial waste have drawn researchers’ attention toward the development of sustainable supply chains and circular economy approaches. In this context, the textile industry, particularly polyester carpet, has become one of the main sources of environmental pollution due to high consumption levels and the non-biodegradable nature of its materials. Despite advantages such as affordability and attractive appearance, these products create significant waste management challenges due to their short lifespan and multilayer structure. Conventional disposal methods such as landfilling and incineration are not only unsustainable but also result in severe environmental impacts, including the release of microplastics and toxic gases. In this regard, closed-loop supply chains have been introduced as an effective solution to integrate forward and reverse flows and reduce environmental impacts. However, there is still a lack of comprehensive models that simultaneously consider both economic and environmental objectives in the carpet industry. Therefore, this study proposes a multi-objective mixed-integer linear programming model for designing a sustainable supply chain in the Iranian polyester carpet industry.
Methodology
In this study, a multi-objective mixed-integer linear programming (MILP) model is developed for designing a closed-loop supply chain network. The network consists of multiple echelons, including suppliers, manufacturing plants, retailers, customer zones, collection centers, refurbishment facilities, recycling centers, and industrial companies. In the forward flow, raw materials are delivered to manufacturing plants, where polyester carpets are produced and distributed to customer zones through retailers. In the reverse flow, used products are collected and classified based on their condition; reusable products are sent to refurbishment centers, while non-reusable items are directed to recycling facilities. The recycling process includes shredding and melt-spinning stages, enabling the recovery of polyester fibers. The proposed model includes two objective functions: minimizing total network cost and maximizing environmental performance through the use of eco-friendly materials and clean technologies. To solve this multi-objective problem, three approaches fuzzy programming, weighted goal programming, and multi-choice goal programming are applied. The model is implemented and solved in GAMS based on a real case study from the Iranian carpet industry.
Results and Discussion
The results indicate that different solution approaches exhibit different behaviors in balancing economic and environmental objectives. The fuzzy programming approach achieves the best environmental performance and provides a satisfactory balance between conflicting objectives, although this comes at the cost of higher total system cost. In contrast, weighted goal programming and multi-choice goal programming approaches, which focus on minimizing deviations from aspiration levels, yield lower costs but weaker environmental performance. The findings also show that refurbishment plays an important role in reducing costs and improving sustainability, while recycling enhances resource efficiency by returning materials to the production cycle. Furthermore, sensitivity analysis indicates that parameters such as demand, return rate, and recycling capacity have a significant impact on system performance, highlighting the importance of their optimal configuration.
Conclusion
This study presents a comprehensive multi-objective framework for designing a sustainable closed-loop supply chain in the polyester carpet industry, enabling simultaneous decision-making based on both economic and environmental criteria. The results show that the fuzzy programming approach achieves the best balance between cost and sustainability, while goal-based approaches are more suitable under strict financial constraints. From a managerial perspective, the development of collection infrastructure, expansion of refurbishment and recycling facilities, and adoption of clean technologies are key strategies for improving system sustainability. Moreover, collaboration among manufacturers, policymakers, and consumers plays a crucial role in the successful implementation of such systems. Ultimately, the findings demonstrate that integrating environmental considerations into supply chain design not only reduces negative environmental impacts but also enhances overall system efficiency and long-term sustainability.
For future research, incorporating uncertainty in key parameters such as demand, return rate, and cost through fuzzy or stochastic approaches can improve model accuracy. In addition, the use of metaheuristic algorithms for solving large-scale problems, the assessment of advanced environmental indicators such as carbon footprint, and the inclusion of social sustainability dimensions such as job creation in collection and recycling centers can further enhance the model’s applicability and development under real-world conditions.

Keywords

• Closed-Loop Supply Chain
• Carpet Refurbishment
• Environmental Considerations
• Polyester Carpet

Main Subjects

• supply chain management