Sludge dewaterability and floc structure in dual polymer conditioning

Sludge conditioning by single and dual polymers was investigated in this study. Capillary suction time (CST) and specific resistance to filtration (SRF) were utilized to assess sludge dewaterability. Zeta potentials, flee sizes, and fractal dimensions were also measured to characterize the sludge. An ultrasonic field was applied to estimate flee strength. In single polymer conditioning, the sludge conditioned with the non-ionic polymer showed a better dewaterability than sludge conditioned with the cationic polymer. Non-ionic polymers generated flocs with a larger size, owing to the higher molecular weight. Experimental results indicate that sludge conditioned with dual polymers showed a better dewaterability with less chance of overdosing compared with sludge conditioned with a single polymer. No correlation between flee size and dewaterability was observed. Compared with single polymer conditioning, dual polymer conditioning generated flocs with enhanced strength. (C) 2001 Elsevier Science Ltd. All rights reserved.