| Abstract: | This paper examines the hydrophobicity and the surface charge of a range of foaming and nonfoaming activated sludges, together with an appraisal of the species involved. The results show that the solids in foaming sludges possess a higher hydrophobicity than those in nonfoaming sludges. The data also indicate that there are two distinct hydrophobicity/surface charge trends, depending on whether the sludges are foaming or nonfoaming. Sludges in which Nostocoida limicola was the dominant species did not conform to these patterns. In addition, the stability of the foam formed by these sludges was significantly lower. |
