Planning decentralized wastewater treatment systems by comparing through TOPSIS

This study evaluates 10 case studies of decentralized wastewater treatment systems (DEWATS) and compares them based on their environmental and economic performance. The aim is to identify the best treatment system composed of specific treatment processes that can be used in the future for hospitals, universities/colleges, and small communities. The comparison was conducted using the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) method of multiple criteria decision-making. According to the TOPSIS method, systems are ranked from 1 to 10 by normalizing and weighting the decision matrix criteria, measuring the alternative's distance from the ideal best to worst value, and then calculating the performance score of each system. The study found that the H4 system, which includes a septic tank, anaerobic baffled reactor, anaerobic filter, horizontal filter, and pond, achieved the highest performance score. Therefore, the processes of the H4 system are recommended as the best alternative for DEWATS. This study may therefore assist stakeholders on their decision to implement DEWATS in similar facilities.