Activated starch as an alternative to polyacrylamide-based polymers for in-line filtration of low turbidity source water

Polyacrylamide-based polymers are commonly used as coagulant aids in water treatment, but there is some concern about their potential toxicity. This work investigated a novel alternative, Hydrex TM 3841 activated starch polymer, as a coagulant aid for alum to treat low turbidity source water at pilot scale using in-line filtration. Compared to two typical polyacrylamide-based polymers, Magnafloc ® LT22S and Superfloc ® A-100, at an alum dose of 0.95 mg Al/L, activated starch could reach a similarly optimal unit filter run volume (∼116 m 3 /m 2 ), while the required dose (0.48 mg/L) was approximately 2–10 times higher than those for the other two types of polymers. Since polymer cost has been reported to be a minimal proportion of the total chemical cost at a water treatment plant, activated starch may be a promising alternative to polyacrylamide.