A hybrid life cycle assessment based fuzzy multi-criteria decision making approach for evaluation and selection of an appropriate municipal wastewater treatment technology

Abstract

Multiple-criteria decision-making (MCDM) has become a main area of research for dealing with complex environmental decision-making problems. In this paper, a hybrid life cycle assessment (LCA) based fuzzy MCDM methodology is developed for the evaluation and selection of appropriate municipal wastewater treatment (WTT) technology based on expert opinion and questionnaires. Further, the study also aims to identify the key evaluation criteria in the process of selecting WTT from a sustainability perspective. The use of fuzzy MCDM in wastewater management has the advantage of rendering subjective and implicit decision-making more objective and analytical, with its ability to accommodate both qualitative and quantitative data. This study provides a systematic approach towards WWT technology selection, in which four-phase procedure is proposed. First, the appropriate technology evaluation and selection criteria were derived from the literature, LCA and experts’ opinion. Next, in the second stage, the fuzzy Delphi method was used to evaluate and screen the critical factors for the evaluation of technology alternatives by interviewing the experts. Twelve criteria including sustainability and those derived from LCA and life cycle costing were obtained consisting of both qualitative and quantitative criteria. In the third stage, the weights of the selection criteria as the measurable indices of the WWT technologies were determined by fuzzy pairwise comparison matrices of analytic hierarchy process. Finally, the fuzzy the technique for order of preference by similarity to ideal solution technique was used for ranking the alternatives. The six most commonly used WWT technologies, viz. sequencing batch reactors (SBR), membrane bioreactor (MBR), moving bed bio-film reactor (MBBR), soil biotechnology, facultative aerated lagoon and activated sludge process were evaluated. The present study is the first study of its kind to develop a hybrid LCA-based fuzzy MCDM methodology for the selection of best WWT alternatives. Results illustrated that advanced technologies, MBR, SBR and MBBR are the preferred options with MBR the most preferred one followed by SBR and MBBR. The developed technology assessment framework enables decision makers to understand the complete evaluation and selection process better and provide a more accurate, effective, and systematic decision support framework. The framework is superior to existing methods since it has the capability of representing vague qualitative data and presenting all possible results with different degrees of membership. The framework developed and applied in this work will help identify appropriate WWT technologies for various decision-making situations faced while managing wastewaters.