Method and apparatus for measuring the fouling potential of membrane

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. In one embodiment, the cleaning frequency membrane used in the testing is comparable to the filter support used in the reverse osmosis system, but has no separation membrane thereon. A test cell for measuring permeation through the cleaning frequency membrane is provided.