Abstract: Liquid solution separation (e.g., concentration and/or desalination) methods and related systems involving membrane separators having at least one-semipermeable membrane are provided. In some instances, at least some of the membrane separators permit a portion of solute in a retentate side input stream to pass through the semi-permeable membrane. In some instances, multiple membrane separators are employed, with the membrane separators having different solute permeabilities (e.g., due to varying pore size and/or molecular weight cutoffs). The methods and systems may be configured such that the ratio of mass flow and/or concentration of solute entering the retentate sides of the membrane separators are relatively high compared to the mass flow and/or concentration of solute exiting the retentate sides of the membrane separators.

Abstract: A serial filtration system for liquid purification includes a preliminary-stage reverse-osmosis (RO) module and a first-stage, high-permeability, reverse-osmosis (HiRO) module. Both modules include (a) a chamber including an inlet, a retentate outlet, and a permeate outlet, and (b) at least one membrane separating the chamber into a retentate side on an upstream side of the membrane and a permeate side on a downstream side of the membrane. The membrane in the preliminary stage is an RO membrane, while the membrane in the first stage is an oxidized membrane. The first-stage inlet is in fluid communication with the preliminary-stage, retentate outlet; and the oxidized membrane in the first stage, comprises an oxidized polyamide active layer coated on a porous support, wherein the oxidized polyamide active layer has an atomic oxygen/nitrogen ratio of at least 1.5.

Abstract: A serial filtration system for liquid purification includes a preliminary-stage reverse-osmosis (RO) module and a first-stage, high-permeability, reverse-osmosis (HiRO) module. Both modules include (a) a chamber including an inlet, a retentate outlet, and a permeate outlet, and (b) at least one membrane separating the chamber into a retentate side on an upstream side of the membrane and a permeate side on a downstream side of the membrane. The membrane in the preliminary stage is an RO membrane, while the membrane in the first stage is an oxidized membrane. The first-stage inlet is in fluid communication with the preliminary-stage, retentate outlet; and the oxidized membrane in the first stage, comprises an oxidized polyamide active layer coated on a porous support, wherein the oxidized polyamide active layer has an atomic oxygen/nitrogen ratio of at least 1.5.