Patent ID: 8216473

Claim:
A process for processing an original solution into two process streams; the process comprising steps of: (a) providing a cascading reverse osmosis system including at least: (i) a first, final, solvent outlet-generating reverse osmosis unit; (ii) a first, final, concentrate outlet-generating reverse osmosis unit; and, (iii) an intermediate reverse osmosis membrane unit system comprising multiple reverse osmosis units; and, (b) operating the reverse osmosis system to process the original solution such that: (i) concentrate from the first, final, solvent outlet-generating reverse osmosis unit is directed into the intermediate reverse osmosis membrane unit system, as at least part of a feed stream thereto; (ii) reduced-solute solvent from the intermediate reverse osmosis membrane unit system is directed into the first, final, solvent outlet-generating reverse osmosis unit as at least part of an inlet feed stream thereto; (iii) concentrate from the intermediate reverse osmosis membrane unit system is directed into the first, final, concentrate outlet-generating reverse osmosis unit as at least part of an inlet feed stream thereto; (iv) each reverse osmosis unit in the intermediate reverse osmosis membrane unit system is conducted with both a high pressure side inlet feed and a low pressure side inlet feed; (v) each reverse osmosis unit of the intermediate reverse osmosis membrane unit system provides a high pressure side concentrate outlet and a low pressure side outlet; and, (vi) the original solution to be processed is directed into at least one of the: first, final, solvent outlet-generating reverse osmosis unit; the intermediate reverse osmosis membrane unit system; and, the first, final, concentrate outlet-generating reverse osmosis unit; (c) the intermediate reverse osmosis membrane unit system being operated with multiple reverse osmosis membrane units; (d) the intermediate reverse osmosis membrane unit system being operated with no pressure reduction step in liquid flow paths between any two of the reverse osmosis membrane units therein; and, (e) a low pressure side outlet flow from at least one reverse osmosis membrane unit in the intermediate reverse osmosis membrane unit system being split into two streams including: (i) a first stream which is directed into a low pressure side inlet stream of a next permeate direction reverse osmosis membrane unit in the intermediate reverse osmosis membrane unit system; and, (ii) a second stream which is pressurized and is then directed into a high pressure side outlet stream from the next, upstream, concentrate flow-direction, reverse osmosis membrane unit in the intermediate reverse osmosis membrane unit system.