Can polyacrylamide flocculation be used for alum coagulation?

There is a growing interest in the use of ultrafiltration (UF) for the treatment of micro-polluted surface waters for drinking water supplies. Effective pretreatment is required to mitigate membrane fouling and in this paper we have evaluated the application of polyacrylamide (PAM) flocculation with alum coagulation.

Are Pam flocculants toxic?

The potential environmental hazard does not concern the PAM itself, which is generally considered as not toxic (Andersen 2005), but the products of PAM degradation and the residual AMD contained in the flocculants due to incomplete polymerization process (Labahn et al. 2010; Young et al. 2007; Caulfield et al. 2002).

How do coagulant dosage and Pam type affect maturated flocculation?

Ballasted flocculation tests were done with changing coagulant dosage and PAM type. Major influencing mechanism of PAM type was explored via change of zeta potential. PAM type affected floc size, strength and recovery ability at the same AS dosages. Role of polymer-enhanced cohesion determined maturated floc physicochemical nature.

How do high molecular weight PAMS work as flocculants?

High molecular weight PAMs (10 6 to 10 7 g mol −1) work as flocculants by causing suspended particles to bind together to form larger aggregates, which can settle out quickly from solution leaving a clear supernatant (Heath et al. 2006).

Are cationic polyacrylamides better than anionic polyamides?

They suggested that cationic polyacrylamides (PAM) produced floc aggregates with larger size, greater shear-resistant ability and higher regrowth capacity than anionic one, arising from the contribution of charge neutralization and bridging effects , , .

Can a high mw Pam be used as a pretreatment method?

These results demonstrate that the combination of a high MW PAM with alum as a pretreatment method of UF process can effectively improve the floc properties and cake layer structure for controlling membrane fouling and producing high quality treated water. 1. Introduction