Selection of a sustainable treatment process for removal of microplastics from wastewater by axiomatic design and PROMETHEE

Microplastics cause alarming levels of pollution in the receiving water environment. Therefore, various advanced treatment processes are being investigated to prevent microplastics from entering the receiving water environment. In this study, microplastic (MP) treatment processes were evaluated in terms of efficiency, economy, sustainability, and applicability using multi-criteria decision-making methods (MCDM). Fuzzy Axiomatic Design and fuzzy Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE) methods were preferred as MCDM. Photocatalytic degradation, membrane filtration, conventional wastewater treatment plant (WWTP), coagulation, adsorption, biological degradation, electrocoagulation, electrooxidation and chemical oxidation alternatives were determined for MP removal. These alternatives were examined with the criteria of MP removal efficiency, operation and maintenance cost, secondary waste generation, required installation space, green process, operating difficulty and industrializability. According to the results of both MCDM methodologies, electrocoagulation was determined as the most suitable MP treatment alternative, while conventional WWTP was the least preferred alternative. Finding that the most suitable and least suitable alternatives were found to be the same in both methodologies showed that the MCDM methodologies used are applicable in solving the current problem.