Membrane element and process for making the same

A reverse osmosis module comprising:

• a. a pressure vessel (8);
• b. pressure vessel (8) comprising a tubular container (81) and a cap (82) attached the upstream end of the tubular container, the cap (82) contains a feed water inlet (83) in the middle of the cap (82);
• c. tubular container (81) has a treated water outlet (84) and concentrated outlet (85) at the downstream end of the tubular container (81);
• d. spiral wound reverse osmosis membrane element (1) placed inside of the tubular container (81);
• the reverse osmosis membrane element (1) comprising:
• (i) a first reverse osmosis membrane set (2) spirally wound around a first central water collection tube (3);
• (ii) a second reverse osmosis membrane set (4) spirally wound around a second central water collection tube (5);
• and
• (iii) a connector (6) connecting the first central water collection tube (3) in fluid communication with the second central water collection tube (5);
• wherein the outer area (221) remote from the first central tube (3) of the side surface (22) of downstream end (21) of the first reverse osmosis membrane set (2), and the outer area (421) remote from the second central tube (5) of the side surface (42) of the upstream end (41) of the second reverse osmosis membrane set (4) are both sealed;
• and the outer area of joint (7) between the two reverse osmosis membrane sets are sealed such that the flow path of concentrated water from the downstream end (21) of the first reverse osmosis membrane set (2) is in fluid communication with the upstream end (41) of the second reverse osmosis membrane set (4);
• and wherein side surface of upstream end (23) of the first reverse osmosis membrane set (2) and side surface of downstream end (43) of second reverse osmosis membrane set (4) are fully sealed by means of glue and upstream end (32) of the first central water collection tube (3) are sealed by means of glue;
• and downstream end (52) of the second central water collection tube (5) is connected impermeably with treated water outlet (84);
• e. brine seal (9) is provided around the joint (7) between the two sets of reverse osmosis membrane, and between the reverse osmosis membrane element (1) and the inner wall of the tubular contain (81) to prevent the feed water flow from bypassing the spiral wound reverse osmosis membrane element (1);
• wherein the reverse osmosis module being arranged such that when the reverse osmosis module operates, the feed water is pumped inside of the pressure vessel (8) through the feed water inlet (83) and pushed inside of the first reverse osmosis membrane set (2) through the outside surface (24) of the first reverse osmosis membrane set (2), the feed water is filtered by the first reverse osmosis membrane set (2) to generate treated water and concentrated water and the treated water flows inside of the first central water collection tube (3) while the concentrated water flows out from the inner annular area (222) of the side surface (22) of the downstream end (21) of the first reverse osmosis membrane set (2) and into the inner annular area (422) of the side surface (42) of the upstream end (41) of the second reverse osmosis membrane set (4);
• and
• wherein the concentrated water is filtered again by the second reverse osmosis membrane set (4) and flows out from the outside surface (44) of the second reverse osmosis membrane set (4) and the treated water is discharged through the treated water outlet (84) and the concentrated are discharged through the concentrated water outlet (85).