Optimizing Sustainable Biorefinery Production with Controllable Waste, Emission, and Wastewater from the Footwear Industry

Circularity and sustainability are gaining more attention in production economics and supply chain management. An inventory model that examines the sustainable strategies adopted in each production stage, from the raw material preparation to the post-consumption practices adopted by the customer, is a need of this era. A multi-echelon inventory model adopted for the leather footwear industry consisting of a primary supplier, secondary supplier, manufacturer, retailer, and customer is discussed in this paper. The proposed model aims to maximize the expected average integrated total profit of the system with optimal lot size and optimal investment technologies used to reduce waste, minimize emissions, and control the wastewater from the footwear industry. A genetic algorithm (GA) is used to find the optimal values of the decision variables. The feasibility of the proposed model in the leather industry has been validated through both numerical and theoretical analyses. The adoption of green investment in the secondary supplier leads to a 60.47% reduction in emission costs, while the manufacturer achieves a 71.99% reduction, compared to the scenario where no investment is made. The study concludes that the adoption of sustainable strategies and circular practices, coupled with government assistance, could help the leather footwear industry achieve its maximum profit.