Hyperfiltration system suitable for household use

1. 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%.

2. The method of claim 1 wherein the pump ( 30 ) is deactivated and reactivated between the steps of producing the permeate and flushing the spiral wound membrane element ( 28 ).