Sludge Valorization Process for Waste-to-Value-Added Products: Process Simulation, Sustainability Assessment, and Fuzzy Multi-Criteria Decision Making

In this paper, a decision-making framework based on process simulation and the fuzzy PROMETHEE II method was proposed to evaluate the performances of the waste management alternatives considering the situation of lacking data and uncertainty. Process simulation and fuzzy multi-criteria decision-making methods were applied to deal with the problem of insufficient data and uncertain information from linguistic descriptions. First, a criteria system covering environmental, economic, technical, and social aspects was established for sustainability evaluation. Then, sustainability assessment was conducted based on the results of process simulation. The fuzzy best-worst method was applied to obtain the fuzzy weights for the criteria based on the preferences of stakeholders, and the fuzzy PROMETHEE II approach was presented to generate the ranking for all the alternatives. A case study for the prioritization of sludge-to-energy technologies was carried out to demonstrate the feasibility of the proposed framework. Sensitivity analysis and uncertainty analysis were also conducted to verify the stability and robustness of the model. Results indicate the effectiveness of the proposed model on providing reference for the waste-to-energy alternatives ranking and giving constructive suggestions for the industry and future research directions. The constructed model can not only provide useful references for decision-makers but also can inspire researchers to investigate biomass management technologies in a similar framework, and the application may even extend to other fields.