Abstract: A process and apparatus for membrane treatment of a feed liquid to form a product liquid includes feeding a feed liquid, typically an aqueous solution such as tap water, to a primary membrane. The primary membrane separates the feed liquid into a primary membrane retentate which is retained by the primary membrane, and a primary membrane permeate. The primary membrane retentate is then fed to one or more supplemental primary membranes, or to a secondary membrane. The primary membrane retentate (or supplemental primary membrane retentate if a supplemental primary membrane is employed) is separated by the secondary membrane into a secondary membrane retentate which is retained by the secondary membrane, and a secondary membrane permeate passes through the secondary membrane. The secondary membrane retentate may either be collected and disposed of, or may be fed to one or more supplemental secondary membranes.

Abstract: A treatment tank for a water conditioning apparatus has a tank head with a wall, a rim defining a through hole in the wall and a tank ring fixed to the rim. The tank ring is coaxial with the tank head and extends generally axially. The tank also has a generally cylindrical flange defining a nipple portion with a peripheral wall that has a lower edge. The flange also has a shoulder extending radially from the nipple portion with a top surface and an outer peripheral wall extending downward from the top surface. A fastener assembly is engageable on the top surface of the shoulder for securing the flange on the tank head through contact between the fastener assembly and the tank ring.

Abstract: An improved method for regenerating ion exchange resin in a treatment tank having a flow direction, which includes the steps of providing a supply of regenerant under pressure into the tank, and introducing the regenerant into the tank in an opposite flow direction to the treatment flow direction. In the preferred embodiment, the regenerant is a combination of CO2 which is mixed with water to form carbonic acid and citric acid. This mixture is then introduced into the treatment tank without storage.

Abstract: A process is disclosed for treatment of dialysis feedwater using ozone. The ozone is added to the feedwater storage tank. It is removed prior to use of the feedwater in dialysis using ultraviolet light. A process for disinfecting a dialysis feedwater loop using ozonated water is also provided.