Micro processes in coagulation

• Published in: Water research (Oxford) 1976, Vol.10 (2), p.143-147
• Main Author: Licsko, I
• Format: Article
• Language: English
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/0043-1354(76)90114-7

A series of experiments is described, in which the optimal pH range in clarification, as well as the conditions affecting the interactions between the flocs and the dispergated colloidal particles were investigated. These experiments were carried out using a natural colloidal dispersion: the water of the River Danube. In the experiments the Zeta-potential and turbidity were measured, accompanied on occasion by microscopic observations. Aluminium sulphate was invariably used as the coagulant. From the experimental results the following conclusions have been arrived at: (1) optimal conditions for clarification were found to exist within a definite pH range, in which the Zeta-potential was virtually unaffected even by large changes in the concentration of the coagulant, whereby a saving in coagulant becomes possible: (2) in studying the interactions between the flocs and dispersed colloid particles, the freshly formed aluminium hydroxide sols were found to become adsorbed on the discrete colloid particles. The large “aged” flocs are no more capable of impairing substantially the stability of the colloidal dispersion.