Mathematical Modeling to Evaluate and Select the Best Coagulant in Drinking Water Treatment, using Multi-Attribute Group Decision Making

Urbanization, population growth, and changing the social attitude toward water consumption has increased the drinking water demand. Coagulation is one of the essential processes in drinking water treatment plants in which the particles and microorganisms attached to those particles are settled down and removed. While there are different kinds of coagulants and coagulant aids are being used in drinking water treatment plants, it is always important to select the best available options considering important factors (criteria) such as efficiency, cost, and effect on health and environment. These three criteria are used to compare three alternatives including ferric chloride, poly aluminum chloride, and alum associated with corn starch as a coagulant aid. To find the best coagulant combination, we performed multi-attribute group decision making (MAGDM) using the conventional Cook and Seiford method. After mathematical modeling, Hungarian method was used to solve the problem. Then, the priority among the coagulants was determined based on defined criteria. The results of this article showed that ferric chloride and corn starch was ranked first among the alternatives. Poly aluminum chloride and alum with corn starch was ranked second and third respectively. The analysis and results presented in this article have significant implications for different operating strategies and material selection in water treatment plants.