SEQUENTIAL FILTRATION SYSTEMS FOR LIQUID PURIFICATION AND SEQUENTIAL FILTRATION METHODS

Abstract

The invention relates to a sequential filtration system for liquid recirculation comprising a reverse-osmosis (RO) primary stage module and a high-permeability, reverse-osmosis (HiRO) primary stage module. Both modules comprise (a) a chamber containing an inlet, an outlet for the osmotic material, and an outlet for the osmotic fluid, and (b) at least one membrane dividing the chamber into an osmotic side upstream of the membrane and an osmotic side downstream of the membrane. The membrane in the primary stage is an RO membrane, while the membrane in the primary stage is an oxidizing membrane. The primary stage inlet circulates the liquid with the primary stage osmotic material outlet; and the first-stage oxidation membrane, consisting of an oxidized polyamide active layer coated on a porous substrate, where the oxidized polyamide active layer has an oxygen / nylon ratio of at least 1.5. The invention also describes a sequential filtration method using a sequential filtration system.