Abstract
Dead-end ultrafiltration (UF) was integrated to a conventional drinking water treatment process (pre-oxidation, coagulation-flocculation, decantation and sand filtration) as a strategy for arsenic control in drinking water. Different turbidities (control, 300 and 1000 NTU) and arsenic concentration (0.015 – 0.4 mg/L) were considered, in addition to the interference of iron and manganese on arsenic removal as these metals occur concomitantly. The efficiency of coagulation-flocculation processes was assessed, stablishing multilinear regression models for predictive purposes. These are processes highly dependent on surface water quality, in which the average removal of arsenic, iron and manganese decreased as their initial concentration increased, although the removal of colour and turbidity seems not to be a major concern. The results reinforced the limitation of conventional treatment process for attaining the threshold values especially for arsenic and manganese, an issue overcame by the implementation of an UF (RAs: 96.9% RMn: 88.9% and RFe: 99.7%). Not only the efficiency in attaining the threshold values, but the UF performance was reassured by its operation stability, that showed no expressive flux decay (J/J0 > 0.93). A sensitive analysis demonstrated that the implementation of an UF becomes more economically attractive in facilities of a greater treatment flowrate. As the treatment capacity increase (0.108 – 12,690 m3/h) the operating costs decreases (0.98 – 0.81 US$/m3). The overall results suggested that UF can be used to retrofit drinking water treatment plants in view of the increased concentration of arsenic, and other ions as iron and manages, in drinking water sources.
Published Version
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