Designing the Supply chain of microbial proteins from municipal solid waste and sewage

The growing concern for environmental sustainability and limited resources in recent years has stimulated innovative strategies for efficient waste management and sustainable resource utilization. A novel approach in this context involves replacing single-cell proteins based on residues, aiming to reduce reliance on animal protein. The paper has suggested a novel multi-level, multi-period, multi-product mixed-integer linear programming model to design an efficient single-cell protein supply chain network through recycling municipal solid waste and sewage. Seven recycling technologies are considered, and their capacities are optimized. The network investigation involves identifying the location and capacity of centers at each supply chain level, the production technology type used at these centers, and other logistics network management decisions like inventory level and material flow throughout network. The proposed model has been applied in a real case in Iran for a 20-year planning horizon. The production of additional by-products, including electricity, heat, and bio-fertilizer, is also studied. An extensive sensitivity analysis of key parameters, including demand, production center capacities, and costs related to feedstock and final product processing, is conducted. The research revealed that rail transportation was favored by 62% of respondents over road transportation. Furthermore, the study identified the medium capacity level as the most suitable, considering the high production volume, which constituted about 60% of the total output. The evaluation results emphasize the model's efficiency and performance, highlighting its potential to improve and optimize the single-cell proteins supply chain network.