Prioritization of waste management strategies in sugar industry using Fuzzy Analytic Hierarchy Process (FAHP): a sustainable approach

The sugar industry is one of the most important agro-industrial sectors in Iran, generating substantial amounts of organic waste including sugarcane bagasse (SCB), bagasse fly ash (BFA), filter mud (FM) and sugar beet pulp (SBP). Existing studies are predominantly descriptive, focusing on waste types, compositions, or recycling pathways, but lack a systematic framework for prioritizing strategies while simultaneously considering economic aspect and operational/technical feasibility. This study employed the Fuzzy Analytic Hierarchy Process (FAHP) using linguistic variables converted to triangular fuzzy numbers. Two main criteria were economic aspect and feasibility (with the environmental criterion used as an initial filter). Waste management strategies were extracted from a review study and were considered as sub-criteria. Pairwise comparison matrices were completed by 20 experts (11 professors, 7 PhD students, and 2 waste management organization professionals). Weights were calculated via the geometric mean method, with consistency ratios (CR < 0.1) verified. Calculations were cross-validated using Excel 2021 and the FuzzyAHP package (v0.9.5) in R (v4.3.2). The Economic aspect criterion received higher weight (0.61) than Feasibility (0.39). The sub-criteria ranking from two point of view (economic aspect and feasibility) was fuel & energy production (0.25, 0.19), agricultural applications (0.24 - 0.20), industrial application (0.15-0.16), food/pharmaceutical/cosmetic production (0.14-0.14), construction materials production (0.11-0.16) & pollutant purification (0.11-0.15). The Gray Relational Analysis (GRA) was also performed, and the outcomes were seen to be consistent with those of FAHP. Under current economic and technical conditions of Iranian sugar factories, fuel & energy production and agricultural applications emerge as the most suitable strategies.