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ARSENIC REMOVAL BY SOFTENING AND COAGULATION
Description:
Drinking water regulations for arsenic (As) and disinfection by-product precursor materials (measured as TOC) are becoming increasingly stringent. Among the modifications to conventional treatment that can improve removal of As and TOC, precipitative softening and coagulation are the most attractive. This work is aimed at improving As and combined As/TOC removals at existing water treatment plants through two phases of study. The first phase examines As(III) and As(V) behavior during softening in synthetic solutions, both with and without individual ionic constituents present (e.g., calcium, magnesium, manganese, carbonates, NOM and orthophosphates). This allows the precise role of each ion and corresponding solids in mediating As removal during softening to be elucidated. The second phase of the study will examine optimization of As and TOC removal during coagulation. An exhaustive experimental matrix will be completed that provides insight into the role of different NOM sources, acid addition, alkalinity and coagulants in the determining contaminant removals. The final phase of testing will provide confirmation of the most important optimization strategies in real waters.