Abstract: A restrictor in the form of an elongated small duct or tube is employed for brine or concentrate flow control in a reverse osmosis system. The duct is composed of two portions, one end of one of these portions being connected to the brine output of a semipermeable membrane cartridge, and one end of the other of these two portions being connected to the brine disposal system. The other ends of both these duct portions communicate with the interior of a common compartment which, in turn, communicates through a pressure relief or check valve with the purified water collector of the semipermeable membrane cartridge. When the pressure in the purified water collector exceeds the pressure in the compartment, the check valve opens and purified water flows into the compartment and out through the portion of the elongated small duct or tube leading to concentrate disposal.

Abstract: A reverse osmosis apparatus includes a pump for pressurizing feed water introduced into a pressure resistant container in which is slidably mounted a semipermeable membrane cartridge. A rod, attached to an end of the semipermeable membrane cartridge, passes slidably and sealingly through one end of the pressure resistant container and is connected to means for reciprocal actuation. Means, preferably common, are provided to actuate the pump and the rod which imparts longitudinal reciprocal motion to the rod and the membrane cartridge within the pressure resistant container, thereby providing improved turbulence and circulation of the feed water through the semipermeable membrane cartridge over the membrane surfaces. The common means may be in the form of a lever operated by a handle or pedal, or by a power source such as an electric motor.

Abstract: A reverse osmosis apparatus comprises an elongated pressure container housing a plurality of semipermeable membrane cartridges in end-to-end relationship. A separate tap from the product water collector of the semipermeable membrane cartridge or cartridges nearest the inlet of the pressure container for introduction of pressurized feed liquid, produces a high quality water product. A tap from the product water collector of the remainder of the semipermeable cartridges in the pressure container produces a lower quality water product. A minor amount of high quality product water and a major amount of lower quality product water may readily be produced. The process and apparatus may advantageously be employed in the second or subsequent or final step of a multistage process for converting sea water to potable water.