چكيده به لاتين
Due to leachate contamination in groundwater as well as soil, global concerns about improper waste management have increased. Mismanagement of waste causes disease and environmental pollution, and at the same time, it is possible to reduce the environmental damage of waste by converting waste into by-products. With the emergence of the circular economy, increasing recycling rates, reducing landfill rates, and producing energy, biofuel, and compost from waste have become important. The lack of energy and other resources and consumerist behavior creates the need for a comprehensive vision that examines the relationship between waste and its derivatives with water and energy in the form of a water-energy-waste-carbon nexus. In this research, a chain consisting of a waste collector, a municipality, a compost plant, and a power plant that also produces biodiesel in the second model is considered in a Stackelberg game led by the municipality by presenting two mathematical models. The collector collects waste through two channels: one from the city's waste bins and the other through the purchase of recyclable waste from citizens, while each channel has its collection function. In the first model, the municipality collects a fee from the collector for the collection of recyclable waste, which in the second model is for both channels. In addition in the first model, where the government is the leader of the whole supply chain, it supports the citizens, the compost plant, and the power plant with subsidies to control the prices from an economic point of view, and the government sets penalties for the emission of greenhouse gases (GHGs) and the infiltration of leachate. The municipality carries out environmental efforts such as increasing people's awareness and investing in different levels of technology to separate waste and treat leachate. The municipality charges a fee to the collector for the royalty of collecting recyclable waste. The compost plant and power plant produce compost and energy from waste, respectively, and price their product based on the level of environmental efforts such as leachate treatment and GHG control. The results indicate that the environmental policy of the government, compared to the economic and social policy, maximizes the profit of players, environmental efforts of the waste supply chain, waste collection, and recycling, and minimizes landfilling. In the second model, the municipality supports the waste supply chain with penalties and subsidies and simultaneously controls environmental pollution and water and energy consumption with cooperation and the water-energy-waste-carbon nexus approach. The collector sells the recyclable waste of waste bins channel to suppliers and manufacturers and sells the rest to the electricity and biodiesel production plant (biofuel plant) and the compost plant. The biofuel plant also supplies the biodiesel required by the collector in the form of a circular supply chain. In addition, the compost plant tries to treat the leachate and sell it as water for use in agricultural or industrial sectors due to diminishing the costs. Due to the uncertainty of the amount of recyclable waste and the possibility of reducing the profit for the power plant, the risk aversion model for the amount of revenue from the sale of electricity is considered with the conditional value at risk method. The results show that the production of by-products in the waste supply chain reduces water and energy consumption and reduces GHG emissions. Furthermore, the risk aversion model dwindles the risk of the revenue reduction of the biofuel plant from the sale of electricity due to the uncertainty in the received waste of this biofuel power plant. On the other hand, the circular supply chain causes more cooperation among the members, and the collector benefits from zero waste.
