Synthesis of wastewater treatment process (WWTP) and supplier selection via Fuzzy Analytic Hierarchy Process (FAHP)

Wastewater treatment process (WWTP) is essential in every manufacturing company to meet stringent discharge regulations and reduce environmental impacts. The wastewater generated from manufacturing companies need to be treated in a suitably designed WWTP. However, with countless wastewater treatment technologies available in the market, WWTP technologies are usually selected based on vague assumptions and past experience. This approach to technology selection may result in high loss of investment to a company on the long run. In addition, there is a paradigm shift in the current manufacturing industrial practise towards more sustainable practices. Therefore, aspects such as carbon footprint and area footprint are important criteria to be considered during the synthesis of WWTP. In that context, this work aims to develop a decision-making tool in technology selection for the synthesis of WWTPs driven by economic and environmental incentives while meeting with local discharge regulations. As multiple optimisation objectives are involved, Fuzzy Analytic Hierarchy Process (FAHP) is adapted in this work. FAHP assigns weighting factors to criteria and alternatives based on judgements from industrial domain experts. By implementing FAHP, the synthesised final WWTP traded off at a maximum degree of satisfaction of 67.5% had reduce 244.44 USD/day of total investment cost, 134.43 kg CO₂-eq/day of carbon footprint and 2 m² of area footprint. In addition, this work had extended further the decision-making to supplier selection of wastewater treatment equipment based on the wastewater treatment technologies from the synthesised sustainable WWTP. A case study on a sago wastewater treatment process is demonstrated in this work with this proposed approach.