Improvement of sludge dewaterability is greatly hindered by the presence of large amount of water molecules trapped in sludge as a result of its strong hydrophilic characteristics. This study investigates the influence of linear and branched structures of polyacrylamide (PAM) with different charge density (CD) on the electro-kinetics, dewatering and volume reduction of highly stable industrial membrane bioreactor (MBR) sludge. The presence of PAM has induced intensive impact on the flocculation behaviour of the sludge as revealed by supernatant turbidity, zeta potential, capillary suction time (CST), flocs size and settleability. Enhancement of the flocculation and dewatering of sludge is correlated to the surface charge neutralization and bridging mechanisms. The highest optimum dose is obtained as 70 mg.L-1 for linear PAM of 40% CD whereas the lowest value is determined as 30 mg.L-1 for branched PAMs. In all cases, turbidity removal of 99.9% and CST reduction of 51-64% are attained where the linear PAMs revealed the highest CST reduction. As per the flocs formation, higher PAM dose results in bigger flocs until the saturation point, beyond which the surface saturation occurs. The sludge percent volume reduction is measured and correlated to the flocs size and PAM dose. At an optimum PAM’s dose, bigger flocs resulted in higher percent volume reduction, however, at a unified PAM’s dose, branched structure of PAM achieved higher percentage volume reduction having smaller flocs size. Overall, the branched structure of polyacrylamide was more efficient in flocculation of MBR sludge at lower dose of 30 mg.L-1 for both 40 and 60% CD and attaining the highest percentage volume reduction of 58%.

Influence of polyelectrolyte architecture on the electro-kinetics and dewaterability of industrial MBR activated sludge

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.