Is conventional drinking water treatment more economically viable than ultrafiltration in Brazil? A technical, economic, comparative study with risk assessment

Water treatment systems using ultrafiltration (UF) membranes constitute a viable option for producing drinking water for human consumption. The present study aimed to perform a comparative analysis of conventional water treatment and UF. The treatment methods were compared considering the quality of the treated water and the cost of implementing a water treatment plant (WTP) and operating the systems, with a risk assessment of the influence of the deterioration of water quality on costs. Data were obtained from the operations of a conventional WTP in the municipality of Lages, Brazil, and a pilot plant employing UF. In the conventional and UF systems, treated water had turbidity of 1.90 and 0.19 NTU, an apparent color of 2.12 and 0.28 mg L−1 Pt/Co, and pH of 6.94 and 7.04, respectively. Average total cost (ATC) was $0.0496/m3 in the conventional system and $0.0596/m3 in the UF system. Chemical inputs and sludge treatment were the main variables that affected the ATC in conventional treatment, whereas energy and plant costs were the main components affecting the ATC in the UF system. A 30% reduction in water quality increased the ATC by 2.6% for the conventional and 1.5% for the UF system.