A Mathematical Model for Improving Green Supply Chain Performance Using the Concept of Industrial Symbiosis

Industrial ecology is the identification and application of solutions aimed at reducing the environmental effects of products and processes of industrial systems. Industrial symbiosis is a practical application of industrial ecology where manufacturing companies cooperate by creating a network in the field of local exchange of water, energy, or industrial waste recycling. Industrial symbiosis plays an important role in reducing total costs in green supply chain management and its sustainability. Previous researches in the field of green supply chain management have somehow improved its performance by using different tools, but less on the impact of the new and effective industrial symbiosis concept has been discussed. In the current research, for the first time, a mathematical model is presented to apply the concept of industrial symbiosis in green supply chain management to minimize total costs with minimal carbon emissions. The proposed model is a multi-period single product and the lack of demand is allowed. To validate, the proposed model was used in the steel industry with 30 factories during 22 planning periods and with 15 types of raw materials. GAMS software is used to solve the model. The results of the numerical solution of the model have the greatest reduction of carbon emissions and adverse environmental effects with minimum total costs in factories. The sensitivity analysis showed that the value of the objective function of the model is high in relation to the changes in the parameters of the amount of the reproduced product, the rate of the collected return product, the amount of the returned product, the rate of the final disposed product, and the penalty for exceeding the permitted carbon emission limit. The results showed the alignment of green supply chain management policies and industrial coexistence.