Water Supply Vol 6 No 1 pp 211–218 © IWA Publishing 2006
The influence of agitation on aggregates formed during treatment of water with a content of humic substances
L. Pivokonska* and M. Pivokonsky**
*Institute of Hydrodynamics ASCR, Pod Patankou 5, 166 12 Prague, 6, Czech Republic, (E-mail: pivokonska@ih.cas.cz)
**Institute of Hydrodynamics ASCR, Pod Patankou 5, 166 12 Prague, 6, Czech Republic, (E-mail: pivokonska@ih.cas.cz)
ABSTRACT
This study aims to evaluate the influence of agitation conditions on the efficiency of the aggregation process when treating surface water containing humic substances. Laboratory tests were conducted by the jar tests using a variable speed paddle gang stirrer. Optimization of agitation intensity was determined by a Couette flocculator. Suspension was prepared using aluminium chloride as a destabilising reagent. Aggregation efficiency was evaluated by the determination of the degree of aggregation and by the test of aggregation. For all surface waters treated, the optimum treatability was demonstrated by applying higher velocity gradients (G=200-250 s-1). In addition to the laboratory tests, the plant measurements with water containing increased amounts of humic substances were taken to evaluate the aggregation efficiency. The results obtained by the aggregation efficiency measurements show that the intensity of agitation, with the assistance of perforated baffle-type flocculation chamber, attains a low level of velocity gradient (G=22-113 s-1), in contrast to the optimized velocity gradient level (G=200-250 s-1). The aggregates formed in the water treatment plant have an unsuitably wide size-distribution.
Full article (PDF Format)
PAY-PER-VIEW: Buy this article for £20.00 (IWA MEMBER PRICE: £15.00)
|
