PRE-SELECTION OF FLOCCULANTS BY THE SEPARATION ANALYZER LUMIFUGE 114
T. Sobisch, D. Lerche¹; Water Science and Technology, Vol 46 No 4-5 pp 441-446, IWA Publishing 2002.
Abstract: The paper reports on lab-scale investigations in relation to pre-selection of flocculants for sludge
dewatering with decanter centrifuges. Results obtained were compared with CST-measurements
and discussed in relation to findings under field conditions. Experiments were carried out with
sewage sludges of different origin and characteristics and a number of commercial flocculants.
Kinetics of sedimentation and clarification were measured as well as the compression behaviour
and shear sensitivity of sludge sediments. To measure flocculant performance stability against
intensive shearing, total solids in the sludge cake obtained and dewaterability of the sludge cake
during the first 20 – 50 s of centrifugation were compared. A screening test procedure was
developed. Efficient flocculants should produce high residual total solids and good initial
compressibility as well. Lab-scale investigations deliver more reliable results if the dynamic
behaviour of the sludge under centrifugal acceleration is also investigated. The separation analyser
Lumifuge 114 can provide results about the compression behaviour of sludges in the range
between 10 and 100 s. So far no other method or device is known which can deliver such results..
Key words: Flocculant selection • Polyelectrolyte • Sludge dewatering • Stability • Decanter centrifuges • LUMiFuge
¹ L.U.M. GmbH, Rudower Chaussee 29 (OWZ), D-12489 Berlin.Contact us
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