Cost/Benefit Analysis for the Use of Different Coagulants in a Drinking Water Treatment Plant

Abstract

Water scarcity has increased and transformed into a global concern for sustainable development. Safe drinking water is essential for the sustainable development of any urban or rural community. Aluminum and iron salts are the two most used coagulants in conventional water treatment systems for human consumption. Though, limited economic resources in developing countries make it difficult to acquire these chemicals. Thus, there is an urgent need for alternative coagulant studies to assess costs and benefits in terms of removal efficiency in drinking water treatment plants. The main objective of this paper is to show a cost/benefit analysis for the use of different coagulants in a drinking water treatment plant in a developing country. The coagulants evaluated are aluminum hydroxychloride (PACl) + ferric chloride (FeCl₃) and aluminum hydroxychloride (PACl). The efficiencies of turbidity and color removal of each coagulant and the associated costs of dosing these inputs for drinking water treatment are studied. The results show that there are no significant differences in removal efficiencies of turbidity and color between the two coagulants under study: PACl + FeCl₃ and PACl. Though, comparatively the coagulant PACl + FeCl₃ shows better color removal efficiencies, while the coagulant PACl shows better turbidity removal efficiencies. Findings show that the cost-benefit of the coagulants PACl + FeCl₃ and PACl are 0.723 USD/% and 0.857 USD/%, respectively. Namely, coagulant PACl + FeCl₃ shows the lowest cost and the highest efficiency during its use in the drinking water treatment plant under study. The cost-benefit ratio of coagulant PACl + FeCl₃ is 1.19 times lower compared to the coagulant PACl.