Abstract: Disclosed is an economical process for the purification of water containing soluble and sparingly soluble inorganic compounds using single-stage or two-stage membrane processes that integrate membrane water purification with chemical precipitation softening and residual hardness and silica removal from the membrane concentrates using ion exchange resins and silica sequestering media, respectively.

Abstract: Disclosed is a versatile multi-use high water recovery process that integrates the use of water purification membranes including reverse osmosis and nanofiltration with ion exchange water softening resins in a number of configurations that optimize operation and achieve maximum membrane permeate recoveries while eliminating the use of fresh water, sodium chloride and other chemicals needed to regenerate the IX resin. The invention provides process mobility and flexibility that enable selection of optimum process configurations and features to address variability in the Influent Water quality.

Abstract: Disclosed is an economical process for the purification of water containing soluble and sparingly soluble inorganic compounds using single-stage or two-stage membrane processes that integrate membrane water purification with chemical precipitation softening and residual hardness and silica removal from the membrane concentrates using ion exchange resins and silica sequestering media, respectively. The purified water recovery is not adversely affected by design and/or operational deficiencies in the chemical precipitation softening system that may result in higher residual hardness and silica in the supernatant from the clarifier.

Abstract: Disclosed is an improved method for extending the useful life of a reverse osmosis membrane having a high pressure side and a low pressure side, the membrane used for separating soluble and sparingly soluble inorganic materials from an aqueous solution, the process comprising introducing an aqueous solution containing the soluble and sparingly soluble inorganic materials to the high pressure side of a reverse osmosis membrane and pressurizing the aqueous solution on said high pressure side to produce liquid on the low pressure side substantially free of said inorganic materials. Solution containing concentrated inorganic materials is transformed from the high pressure side of the reverse osmosis membrane to a high pressure side of a microfiltration membrane, and soluble inorganic materials transferred to the high pressure side of the microfiltration membrane was precipitated to provide solution containing particles of the inorganic materials.

Abstract: Disclosed is an economical single stage membrane process intended to provide very high overall water recoveries from natural sources or wastewater containing high concentrations of hardness and other inorganic scale-forming compounds while preventing scale formation on the membrane and prolonging the useful life of the membrane. The water is first pre-treated in order to separate all suspended matter using a suitable oil separation device, dissolved air flotation, coagulation, flocculation, clarification, single or multi-media filtration, ultra-filtration, micro-filtration or a suitable combination of these pre-treatment steps. The pre-treated water is then purified using a simple, economical single stage membrane system operating at a suitable pressure depending on the water TDS and desired permeate recovery. In order to prevent scale formation on the membranes, the membrane concentrate is softened using a “low-cost” ion exchange softening resin with high selectivity for hardness precursors.