Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4485405 | Water Research | 2007 | 6 Pages |
Cyclodextrins (CDs) increase the cake solids and drainage rate of belt-pressed biological or primary sludge when added to the sludge slurry along with conventional conditioning chemicals. These benefits are obtained at very low CD dosage. A 2.8 percentage point increase in cake solids was obtained in a full-scale trial with mixed primary and biological sludge from a paper mill. CDs also decrease the specific resistance to filtration and increase the capture rate of solids during belt pressing. Mechanistic studies showed that CDs increase the surface tension of c-PAM polymers in water and reduce the turbidity, indicating that they are able to aggregate the charged polymers, and, by inference, sludge particles treated with the polymer. A mechanism is proposed where CDs reduce excessively charged regions of the polymer-treated surface of the sludge, thereby facilitating its flocculation.