Ultrafiltration and microfiltration module and system

Abstract

A method and apparatus of purifying feedwater to remove impurities including suspended solids therefrom, the method suitable for using in-line water pressure to permeate water through hollow fiber membranes and to backflush the membranes to remove solids collected or deposited thereon.

1 . A method for treating water comprising the steps of: 
 (a) filtering a feed water by flowing feedwater from a feed side of a membrane to a permeate side of the membrane to produce permeate on the permeate side of the membrane;    (b) collecting a portion of the permeate in communication with a resilient energy storage means and deforming the resilient energy storage means from an initial state by applying feed water under pressure to the feed side of the membrane, the collected permeate having a pressure equal to or less than the pressure of the applied feed water;    (c) periodically reducing the pressure on the feed side of the membrane to below the pressure of the collected permeate to flow at least a portion of the collected permeate from the permeate side of the membrane to the feed side of the membrane, the flow of collected permeate being assisted by the resilient energy storage means returning at least partially towards the initial state.    
   
   
       2 . The method of  claim 1  wherein, during step (a), feed water is applied under pressure to the feed side of the membranes and permeate is produced on an on-demand basis by reducing the pressure on the permeate side of the membrane as required.  
   
   
       3 . The method of  claim 2  wherein the pressurized feedwater is applied to the feed side of the membrane over an extended period of time and step (a) is performed during one or more portions of the extended period of time when permeate is required for use.  
   
   
       4 . The method of  claim 1  wherein, in at least some performances of step (b), the collected permeate is pressurized to the static pressure of the feed water applied to the feed side.  
   
   
       5 . The method of  claim 4  wherein at least some performances of step (c) are performed after the collected permeate has been pressurized to a static pressure of the feed water.  
   
   
       6 . The method of  claim 1  wherein the pressure is reduced on the feed side in step (c) by connecting the feed side to a drain.  
   
   
       7 . The method of  claim 6  wherein step c) of  claim 1  is performed by operating a single valve in communication between the feed side of the membrane and the drain.  
   
   
       8 . The method of  claim 1  wherein feed water is applied to the feed side of the membrane during step (c) of  claim 1 .  
   
   
       9 . The method of  claim 8  wherein, during step (c) of  claim 1 , feed water is flushed across the feed side of the membrane.  
   
   
       10 . The method of  claim 1  wherein steps (a), (b) and (c) are performed repeatedly with steps (a) and (b) being performed either before the other or partially simultaneously and each subsequent step (c) being performed after at least a performance of step (b).  
   
   
       11 . The method of  claim 1  wherein a step (b) is performed at least partially after each performance of step (a).  
   
   
       12 . The method of  claim 1  wherein a portion of the collected permeate is discharged for use during a portion of step (a).  
   
   
       13 . The method of  claim 1  wherein feed water is applied to the feed side under pressure throughout steps (a), (b) and (c).  
   
   
       14 . The method of  claim 1  wherein the resilient energy storage means is a diaphragm tank or a tank having a quantity of trapped air.  
   
   
       15 . An apparatus for filtering water comprising, 
 a) a chamber separated internally by a membrane into a feed side and a permeate side;    b) a supply of feed water connected to the feed side of the chamber;    c) a drain connected through a valve to the feed side of the chamber;    d) a network of pipes and valves for distributing water directly to points of use, the network connected to the permeate side of the chamber; and,    e) a tank for collecting a variable volume of permeate under pressure connected to the feed side of the chamber.    
   
   
       16 . The apparatus of  claim 15  wherein at least some of the valves of the network are operable on-demand to expose the network to atmosphere at one or more of the points of use.  
   
   
       17 . The apparatus of  claim 15  wherein the supply of feed water supplies feed water under pressure substantially continuously.  
   
   
       18 . The apparatus of  claim 15  wherein feed water enters chamber from the feed water supply at a point displaced from where feed water exits the chamber to the drain such that a flow of water from the feed water supply to the drain through the chamber flows across the membranes.  
   
   
       19 . The apparatus of  claim 18  wherein feed water enters the chamber from the feed water supply from a point above where feed water exits the chamber to the drain.  
   
   
       20 . The apparatus of  claim 15  wherein the membrane comprises a plurality of hollow fibers oriented vertically.  
   
   
       21 . The apparatus of  claim 15  wherein the valve is connected to a timer or controller configured to periodically open the valve to permit a flow of feed water from the feed water supply to the drain and a flow of permeated water from the tank to the drain.  
   
   
       22 . The apparatus of  claim 15  wherein the tank has a resilient energy storage means.  
   
   
       23 . The apparatus of  claim 22  wherein the tank is a tank having a trapped quantity of air or a diaphragm tank.