Temperature effects on flocculation, using different coagulants
- 1 December 2004
- journal article
- conference paper
- Published by IWA Publishing in Water Science & Technology
- Vol. 50 (12), 171-175
- https://doi.org/10.2166/wst.2004.0710
Abstract
Temperature is known to affect flocculation and filter performance. Jar tests have been conducted in the laboratory, using a photometric dispersion analyser (PDA) to assess the effects of temperature on floc formation, breakage and reformation. Alum, ferric sulphate and three polyaluminium chloride (PACl) coagulants have been investigated for temperatures ranging between 6 and 29°C for a suspension of kaolin clay in London tap water. Results confirm that floc formation is slower at lower temperatures for all coagulants. A commercial PACl product, PAX XL 19, produces the largest flocs for all temperatures; and alum the smallest. Increasing the shear rate results in floc breakage in all cases and the flocs never reform to their original size. This effect is most notable for temperatures around 15°C. Breakage, in terms of floc size reduction, is greater for higher temperatures, suggesting a weaker floc. Recovery after increased shear is greater at lower temperatures implying that floc break-up is more reversible for lower temperatures.Keywords
This publication has 1 reference indexed in Scilit:
- Monitoring floc formation and breakageWater Science & Technology, 2004