Abstract: The present invention provides a method of treating a reverse osmosis membrane for boron rejection enhancement, comprising contacting the reverse osmosis membrane with a chemical coating such as PHMB, wherein the reverse osmosis membrane is part of a single-pass reverse osmosis system is configured to reduce the boron concentration of normal seawater or brackish water to less than a predetermined amount.

Abstract: A composition for minimizing biological and/or colloidal fouling is described, which includes an anionic antiscalant and a cationically charged biocide. Further, a method of controlling fouling is described and achieved by introducing a formulation of the present invention into an aqueous system which uses a separation membrane. The compositions used in the present invention are compatible with such separation systems and preferably prevent membrane fouling.

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.

Abstract: A method of increasing the time-averaged cross-flow filtration flux of a liquid through a porous filter medium over the period of a filtration run, comprising the steps of: (a) flowing the liquid transversely through the filter medium by establishing a pressure differential across the filter medium; and (b) maintaining the filtration flux rate through the filter medium at a preselected substantially constant value during the entire filtration run by applying a variable throttling pressure on the filtrate side of the filter medium and reducing the throttling pressure during the run to control the instantaneous value of the pressure differential as required to maintain the preselected flux rate, such flux rate being greater than the equilibrium flux rate.

Abstract: A method for softening a fluid containing hardness constituents, comprising the steps of: (a) mixing the fluid with sufficient amounts of a softening agent, and previously precipitated hardness constituents in a reactor to establish a softening reaction in the reactor for precipitating a substantial portion of the hardness constituents contained in the fluid; (b) removing a portion of the fluid and precipitated hardness constituents from the reactor as a slurry and filtering the slurry through a cross-flow microfiltration module containing at least one elongated filtration tube, whereby substantially all of the precipitated hardness constituents are removed from the portion of the fluid exiting from the module as filtrate; and (c) returning at least a portion of the filtered out precipitated hardness constiuents exiting from the module to the reactor as the previously precipitated hardness constituents.