Abstract Considering the global challenges arising from industrialization and economic activities, including biodiversity loss, climate change, and deteriorating health conditions, especially in developing countries, achieving sustainable development has become imperative. Sustainable development, which aims to meet present needs without compromising the ability of future generations to meet their own, encompasses three fundamental dimensions: environmental, economic, and social sustainability. Among these, environmental sustainability plays a pivotal role, emphasizing ecosystem preservation and responsible management of natural resources. Recycling, as a key element of environmental sustainability, contributes effectively by reducing waste, conserving natural resources, and lowering pollution and greenhouse gas emissions. Consequently, addressing environmental issues and promoting recycling for resource conservation and environmental sustainability has gained significant importance today. Numerous studies have thus focused on these issues. This research specifically concentrates on the collection, recycling, and utilization of waste materials while examining the government's role as an incentivizing agent. This study investigates the impact of various government incentive policies on the use of recycled materials in producing two substitute products—green and non-green—under two distinct supply chains. For precise analysis, two separate supply chains are considered: one for the green product (manufactured from recycled materials) and the other for the non-green product (produced from primary raw materials). The green supply chain structure includes a collector, recycler, manufacturer, and retailer, while the non-green supply chain consists of a supplier, manufacturer, and retailer. The role of the government as an incentivizing agent is analyzed through supportive policies aimed at enhancing waste collection and reducing environmental pollution. Three different scenarios are examined in this study. In the first scenario, the government influences the supply chains solely by imposing taxes without offering any supportive policies for the green supply chain. In the second scenario, the government incentivizes the green supply chain by subsidizing products made from recycled materials. In the third scenario, the government supports the green supply chain through tax reduction policies. Initially, equilibrium decisions are determined using game theory approaches. Based on the competitive and cooperative behaviors among players, Stackelberg and chain-to-chain models are developed, and equilibrium prices and greenness rates are eva‎luated under various scenarios. Subsequently, analytical comparisons of the implemented models are provided, offering diverse managerial insights. The results indicate that government support, under different scenarios, generally leads to better waste collection rates (government utility) and consequently improves environmental conditions compared to the case where no support is provided for the green supply chain. Moreover, the subsidy policy proves more beneficial for the profitability of green supply chain members and government utility than the tax reduction policy. Finally, a numerical example is presented to assess the impact of changing influential parameters on equilibrium decisions derived from the implemented models. The findings demonstrate that the government can enhance its utility (waste collection) by adopting policies that increase subsidy rates or tax reductions in the green supply chain or by implementing policies to lower tax rates across both green and non-green supply chains.

حامد جعفري

احسان آزاد فارساني , معصومه مسي بيدگلي