Electrophoretic Studies of Coagulation and Flocculation of River Sediment Suspensions With Aluminum Sulfate

Since 1957, microelectrophoresis has been used by water chemists as a tool for investigating the basic mechanisms of coagulation and flocculation. Earlier studies, however, were conducted only on synthetic waters with pure‐clay suspensions, such as montmorillonite, kaolinite, and fuller's earth. In order to apply the results obtained by the previous investigators to water treatment, it seemed desirable to determine whether or not the types of turbidity actually present in several American rivers behave as those in pure‐clay suspensions. Accordingly, clay sediments from three selected rivers – the Sacramento, the Colorado, and the Apalachiocola – were investigated with the same experimental techniques as used previously by Black and his associates. The experiments reported here were performed in the pH range from 3 to 10, with aluminum sulfate dosages of 0, 5, 10, 20, and 50 ppm.