Abstract: Colloidal matter is removed from a fluid flow by first adsorbing a coagulant onto the surface of a finely divided filter media, and thereafter passing a colloid-containing fluid through the filter media. The adsorbing of coagulant is accomplished with the filter off-line, and it is returned on-line for filtering of the fluid. After the coagulant is adsorbed onto the filter media, it is not necessary to continue feeding coagulant during on-line operation, as the adsorbed coagulant captures the colloidal matter in the fluid and retains it on the surface of the filter media. The captured colloidal matter is removed during back washing of the filter media.

Abstract: The optimum antifoulant concentration and cleaning interval for reverse osmosis membranes is determined by providing samples of a liquid to be purified in a reverse osmosis system, the samples having a range of antifoulant concentrations added. The zeta potential for each sample is measured, and the amount of antifoulant that provides the lowest (most negative) zeta potential is selected as the preferred antifoulant concentration. A cleaning frequency sample of the liquid to be purified with the preferred antifoulant concentration is prepared and passed across a cleaning frequency membrane that passes dissolved matter in the permeate but does not pass colloidal material. The rate of change in flow of the permeate of the cleaning frequency sample is measured as a function of time, and the cleaning frequency of the cleaning frequency sample is determined.