Selecting water disinfection processes using fuzzy synthetic evaluation technique

Drinking water treatment strategies generally involve treatment processes such as screening, coagulation/flocculation, sedimentation, and filtration/adsorption followed by disinfection. Disinfection approaches include chlorine/chlorine (chloramine), granular activated carbon with post chlorine (chloramine), ozone/chlorine (chloramine), chlorine dioxide/ chlorine (chloramine), chloramine/chloramine, and ultraviolet radiation/chlorine (chloramine). However, comparative evaluation of these disinfection methodologies and their application to a particular source of water is rare. In this study, a framework for multicriteria decision making has been developed. Human health risk, cost, technical feasibility, and disinfection performance have been incorporated as the criteria for evaluation of the disinfection approach. A fuzzy synthetic evaluation technique has been incorporated where fuzzy triangular membership functions were developed to capture the uncertainties of the basic attributes. This paper compares three disinfection approaches: chlorination, granular activated carbon with post chlorination, and chloramination through a multistage hierarchy risk management model in which the analytical hierarchy process has been used to determine the relative importance of various attributes at different hierarchy levels. The evaluation process was found to be sensitive to the assignment of relative importance of the attributes. Chlorination was evaluated as the best disinfection approach in most of the cases.