Apparatus for reverse osmosis using fluid recirculation

Claim 1

A membrane element pumping and circulation mechanism, comprising: (a) a cylindrical casing acting as a pressure vessel capable of withstanding reverse osmosis pressure; (b) a centrifugal pumping mechanism, within, and at one end of, said pressure vessel, having an impeller driven by a driving means, and having a formed housing circumferentially perforated towards its pump end, so constructed as to provide 360 degree radial discharge and to provide high volume, low pressure flow; (c) a first end plate support at the pump impeller end of the casing, in which fluid input and first output conduits are contained, said first end plate support also being sealingly joined to the casing by a coupling device; (d) a second end plate support at the opposite end of the casing to the impeller end, said second end cap containing a second output conduit running from the interior side to the exterior side for exit of permeate, said second end cap being sealingly joined to the casing by a coupling device; (e) a connector of smaller diameter than the casing sited immediately inside the casing and abutting, on one side, said second end plate support, said connector acting as a restraint mechanism and containing a longitudinal passageway; said connector being arranged so that its passageway is aligned with said second output conduit contained in said second end plate support so that unimpeded throughflow of fluid is possible; (f) a membrane module of overall cylindrical shape of smaller diameter than the casing, but of larger diameter than the connector; said membrane module being held within the casing, at the pump impeller end by said formed impeller housing and, at the other end, by the other side of the connector so that a continuous space exists between the membrane module and the inside surface of the casing; said membrane module having a central, longitudinal passageway into which permeate passes, said membrane passageway being sealed at the impeller end by a sealing means and aligned at the connector end with said connector in such a manner that permeate may flow from said membrane passageway into the adjoining passageway of said connector; wherein said input and first output conduits contained in said first end plate support are arranged in such a manner that fluid entering the input conduit is driven along the space between the membrane module and the inside surface of the casing, towards the connector end, where said fluid enters the membrane in which a first portion of the fluid passes into said membrane passageway as permeate which then passes through said connector passageway to said second output conduit, and a second portion of non-permeate fluid returns to the impeller through the membrane module so as to be removed as concentrate via the output conduit or to be recirculated by mixture with more incoming fluid.