Hyperfiltration system suitable for household use

A method for treating a source of feed water (40) without using recirculated brine or a permeate holding tank, comprising the steps:

• i) obtaining a hyperfiltration system (10) comprising:
• a vessel (20) having a feed inlet (22), a permeate outlet (24), and a concentrate outlet (26);
• at least one spiral wound membrane element (28) located within the vessel (20);
• a pump (30) having a low pressure side (32) in fluid communication with the source of feed water (40) through a junction point (42), and a high pressure side (34) in fluid communication with the feed inlet (22);
• a permeate valve (50) connected to the permeate outlet (24) and adapted to selectively direct permeate flow between a treated water outlet (52) and the junction point (42);
• a flow path (60) between the concentrate outlet (26) and a discharge (62) which is characterized by being unconnected to the low pressure side (32) of the pump (30);
• and
• a flow restrictor (64) located along the flow path (60) and adapted to impose a variable resistance to concentrate flow between a high and low value;
• ii) activating the pump (30) to force water from the source of feed water (40), into the feed inlet (22) of the vessel (20) and through the spiral wound membrane element (28) to produce a permeate that exits the vessel (20) through the permeate outlet (24) and concentrate that exits the vessel (20) through the concentrate outlet (26), and while the pump is activated:
• iii) producing the permeate at the permeate outlet (24) by actuating the permeate valve (50) such that the permeate is directed to the treated water outlet (52) and actuating the flow restrictor (64) such that the low value of resistance is imposed upon the concentrate flowing to the discharge (62),
• iv) flushing the spiral wound membrane element (28) by actuating the permeate valve (50) such that the permeate is directed to the junction point (42) while no permeate is directed to the treated water outlet (52) and actuating the flow restrictor (64) such that the high value of resistance is imposed upon the concentrate flowing to the discharge (62), and
• v) deactivating the pump (30);
• and wherein:
• a) the step of producing the permeate at the permeate outlet (24) is characterized by operating the vessel (20) at a permeate recovery of from 25 to 70% wherein the permeate recovery is defined as the total permeate volume leaving the vessel compared to the volume of feed water entering the vessel;
• and
• b) the step of flushing the spiral wound membrane element (28) is characterized by operating the vessel (20) at a permeate recovery of from 70 to 97%.