Evaluation of activated starch as an alternative to polyacrylamide polymers for drinking water flocculation

Polyacrylamide polymers (PAM) are one of the most common water treatment chemicals used in clarification processes. Concerns have been raised with regards to the aquatic and human toxicity of acrylamide monomer. Greener polymers, produced using potato starch, were investigated at lab-scale as a potential non-toxic alternative to the use of PAM within a ballasted flocculation process (Actiflo^®). Even under extreme temperature (1 °C), starch and PAM showed comparable turbidity removal performances, although higher starch dosages (four to five times) were needed to achieve such results. Compared to PAM, activated starch polymers also benefited from the use of lower mixing energy and smaller microsand. A slight biodegradable dissolved organic carbon (BDOC) release (≈0.15 mg C/L) was also measured while using starch polymer, but this did not impact trihalomethane and haloacetic acid formation. These results indicate that activated starch polymers represent a promising alternative to the use of PAM polymers in a ballasted flocculation process.