Method and apparatus for purifying fluids

• US 4,784,771 A
• Filed: 08/03/1987
• Issued: 11/15/1988
• Est. Priority Date: 08/03/1987
• Status: Expired due to Fees

• Current Assignee: Environmental Water Technology Incorporated
• Original Assignee: Environmental Water Technology Incorporated
• Inventors: Miller, Steven L., Wathen, Ronald L.
• Primary Examiner(s): Spitzer, Robert
• Application Number:
  US07/080,968
• Time in Patent Office: 470 Days
• Field of Search: 210/636, 210/639, 210/652-655, 210/96.2, 210/126, 210/128, 210/129, 210/195.2, 210/257.2
• US Class Current: 210/636
• CPC Class Codes: A61M 1/1656 Apparatus for preparing dialysates
• CPC Class Codes: A61M 1/1668 Details of containers
• CPC Class Codes: A61M 1/1672 using membrane filters, e.g. for sterilising the dialysate
• CPC Class Codes: A61M 1/169 using chemical substances
• CPC Class Codes: A61M 1/365 through membranes, e.g. by inverted trans-membrane pressure [TMP]
• CPC Class Codes: B01D 2321/02 Forward flushing
• CPC Class Codes: B01D 2321/164 Use of bases
• CPC Class Codes: B01D 61/025 Reverse osmosis; Hyperfiltration
• CPC Class Codes: B01D 61/12 Controlling or regulating
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: B01D 65/022 Membrane sterilisation
• CPC Class Codes: C02F 1/441 by reverse osmosis

Abstract

A method and apparatus for purifying and/or separating fluids including passing such fluid from a feed side of a reverse osmosis unit to the product side of such unit and to an ultimate user during a purifying cycle and recirculating residual fluid back to the feed side in bypass relation to the reverse osmosis unit during a treating cycle to introduce suitable treating fluids into the system for disinfecting and rejuvenating the system.

Claims

1. A method of purifying fluid utilizing reverse osmosis comprising:

passing fluid to be purified during a purifying cycle through an open ended feed zone, through a reverse osmosis zone to an open ended product zone and to an end user for a preselected time period;

interrupting said purifying cycle after said preselected time period by closing said feed and product zones and recycling residual fluid in by-pass relation to said reverse osmosis zone from said product zone in direct, continuously circulating flow to said feed zone for a preselected time period during a treating cycle; and

,

introducing treating fluid from a treatment zone in direct, continuously circulating flow into the recycled fluid during said treating cycle to continuously disinfect/rejuvenate and flush said reverse osmosis zone throughout.

2. The method of claim 1, said treating fluid being osmotically active to allow residual fluid to osmotically pass from the product zone through said reverse osmosis zone to said feed zone during said treating cycle.

3. The method of claim 1, said treating fluid being an osmotically active bacteria disinfectant/rejuvenant to allow residual fluid to osmotically pass from said product zone through said reverse osmosis zone to said feed zone to uniformly disinfect the feed, reverse osmosis and product zone.

4. The method of claim 1, said treating fluid being an osmotically active formaldehyde solution having a rejection range of approximately 38% to approximately 50% with respect to the reverse osmosis zone to allow residual fluid to osmotically pass from said product zone through said reverse osmosis zone to said feed zone for a period of approximately one (1) to two (2) minutes to an equilibrium stage, said equilibrium stage lasting approximately one and one-half (11/2) to two (2) hours.

5. The method of claim 1, said treating fluid being an osmotically active hydrochloric acid solution having a rejection range of approximately 97% to approximately 99% with respect to said reverse osmosis unit to allow residual fluid to osmotically pass from said product zone through said reverse osmosis zone to said feed zone for a preseected period to an equilibrium stage to be followed by a flushing stage of a preselected time period.

6. The method of claim 1, said treating fluid being an osmotically inactive alkali such as sodium hydroxide solution which would pass through the reverse osmosis zone from the feed zone to the product zone and be recycled back to the feed zone for a preselected time period to be followed by a flushing stage of a preselected time period.

7. The method of claim 1, said treatment fluid being a flushing fluid which is passed through the reverse osmosis zone from said treatment and feed zone to said product zone and recycled back to the treatment and feed zone for a preselected time period.

8. The method of claim 1, said treatment fluid being passed transverse the path of normal fluid flow through said reverse osmosis zone to be in shear-like, turbulent relation with respect to said normal flow path through said reverse osmosis zone.

9. The method of claim 1, said treatment fluid being a flushing fluid such as water which is passed through the reverse osmosis unit from the treatment and feed zone to the product zone and recycled back in direct, continuously circulating flow to the treatment and feed zone for a preselected time period, said flushing fluid passing through said zones at a controlled flow rate substantially equal to the passing of said flushing fluid to a drain zone.

10. The method of claim 1, said treating fluid being osmotically inactive with said feed zone including a subzone of preselected back pressure to enhance flow of said osmotically inactive fluid through said reverse osmosis zone.

11. The method of claim 1, said treating fluid being osmotically inactive with said feed zone including a subzone of preselected pressure between said reverse osmosis zone and said treatment zone to enhance flow of said osmotically inactive fluid through said reverse osmosis zone.

12. The method of claim 1, including sensing and controlling the introduction of said treating fluid to avoid system overflow and unintentional introduction of undesirable fluids during said treating cycle.

13. A method of purifying fluid utilizing reverse osmosis comprising:

passing fluid to be purified during a purifying cycle for a time period of approximately three (3) to four (4) hours through an open ended feed zone, through a reverse osmosis zone in shearlike relation with the feedside thereof to an open ended product zone and to an end user;

interrupting said purifying cycle at the end of said time period by closing said feed and product zones and recycling residual fluid in by-pass relation to said reverse osmosis zone from the product zone to the feed zone;

introducing an osmotically active formaldehyde solution having a rejection range of approximately 38% to approximately 50% with respect to the reverse osmosis zone to allow residual fluid to osmotically pass from said product zone through said reverse osmosis zone to said feed zone for a period of approximately one to two minutes to an equilibrium stage, said equilibrium stage lasting for a suitable preselected period of time;

passing a flushing fluid at a controlled rate equal to passing said fluid simultaneously to a drain zone through said reverse osmosis unit from said treatment and feed zone to said product zone and recycling same back to said feed and treatment zone for a suitable preselected period of time;

repeating said treatment and flushing step with a solution of hydrochloric acid having a rejection range of approximately 97% to approximately 99% with said initial treating stage lasting for a preselected period of time to equilibrium state and said equilibrium state lasting for a suitable preselected period of time;

passing an osmotically inactive sodium hydroxide solution in similar fashion as said flushing solution but without draining through said zones for a suitable preselected period of time; and

,

repeating said flushing cycle.

14. A fluid purification apparatus comprising:

a primary flow conduit having spaced upstream fluid feed inlet means and downstream fluid product outlet means;

a reverse osmosis means disposed in said primary flow circuit between said fluid feed inlet means and said fluid product outlet means to include a feed side and a product side;

motive means communicating with said primary flow conduit to enhance fluid flow from said feed inlet means through said reverse osmosis means to said product outlet means;

treatment means connectable into said primary conduit to selectively introduce separate treating fluids into said primary flow conduit to treat said reverse osmosis means; and

a secondary flow global loop conduit connectable to extend parallel said primary flow conduit in by-pass relation to said reverse osmosis means to communicate in direct, continuously circulating flow between said product outlet means and said feed inlet means of said primary conduit and with said treatment means to continuously treat said reverse osmosis means throughout when a separate treating fluid is selectively introduced into said treatment means.

15. The fluid purification apparatus of claim 14, said secondary flow global loop conduit comprising part of the product side of said primary flow conduit reconnectable from the produce side in global loop fashion to the feed side of said primary flow conduit.

16. The fluid apparatus of claim 14, said treatment means including separate containers of treatment fluids.

17. The fluid purification apparatus of claim 14, said motive means being a pump positioned in communicative relation with said primary conduit between said feed inlet means of said primary conduit and said reverse osmosis means.

18. The fluid purification apparatus of claim 14, said treatment means being positioned in communicative relation with said primary conduit between said feed inlet means of said primary conduit and said reverse osmosis means.

19. The fluid purification apparatus of claim 14, said motive means and said treatment means being positioned in communicative relation with said primary flow conduit as part of a secondary closed loop conduit nested with said primary flow conduit.

20. The fluid purification apparatus of claim 14, said motive means and said treatment means being positioned in communicative relation with said primary flow conduit as part of a secondary closed loop conduit nested with said primary flow conduit and flow control means regulating relative flow in the primary flow conduit and the flow through said treatment means in said nested loop.

21. The fluid purification apparatus of claim 14, said motive means and said treatment means being positioned in communicative relation with said primary flow conduit as part of a secondary closed loop conduit nested with said primary flow conduit and flow control means including a flow restricting controller in said primary flow conduit and an inlet sensing and control and an outlet check valve arrangement in said treatment means to regulate the relative flow in the primary flow conduit and flow through said treatment means in said nested loop.

22. The fluid purification apparatus of claim 14, said motive means and said treatment means being positioned in communicative relation with said primary flow conduit as part of a secondary closed loop treating conduit nested in parallel relation with said primary flow conduit, said secondary closed loop conduit including a recirculation valve therein to control the amount of fluid circulation therethrough.

23. The fluid purification apparatus of claim 14, said motive means and said treatment means being positioned in communicative relation with said primary flow conduit between said feed inlet means and said feed side of said reverse osmosis means as part of a secondary closed loop treating conduit nested in parallel relation with said primary flow conduit.

24. The fluid purification apparatus of claim 14, said primary flow conduit having a prefilter disposed therein downstream of said feed inlet means with one end of said secondary global loop conduit being connectable to said primary flow conduit between said feed inlet means and said prefilter.

25. The fluid purification apparatus of claim 14, said primary flow conduit having quick connect fittings upstream and downstream said reverse osmosis means to cooperate with quick connect fittings at opposite ends of said secondary flow loop conduit to allow placing of said secondary global loop conduit in quick connected by-pass relation to said reverse osmosis means.

26. The fluid purification apparatus of claim 14, said treatment means communicating with said primary conduit through quick connect fittings.

27. The fluid purification apparatus of claim 14, said treatment means including a treating fluid container having treating fluid inlet and outlet conduits communicating with said primary flow conduit and container valve control means to regulate flow of fluid therethrough to said primary conduit.

28. The fluid purification apparatus of claim 14, said treatment means including a treating fluid container having treating fluid inlet and outlet conduits having quick connect fittings communicating with quick connect fittings in said primary flow conduit and valve control means cooperating with said container to regulate flow of fluid through said container to said primary conduit.

29. The fluid purification apparatus of claim 14, said primary conduit including a solvent feed control means disposed in said primary conduit to control the supply of fluid to be purified in accordance with the introduction of treatment fluid.

30. The fluid purification apparatus of claim 14, said primary conduit further including a fluid feed control means including a rinse control valve in said primary flow conduit downstream of said feed inlet means and a flow control restrictor in said primary conduit in parallel with said rinse control valve to control the supply of fluid therethrough in accordance with the introduction of treatment fluid.

31. The fluid purification apparatus of claim 14, said primary conduit including a flow restrictor and said treatment means including a vented treating fluid container having treating fluid inlet and outlet conduits communicating with said primary flow conduit and level sensing and check valve members cooperating with said container inlet and outlet to regulate flow of fluid through said container to said primary conduit.

32. The fluid purification apparatus of claim 14, said primary circuit including fluid drain control means and a fluid condition monitor means operative to open said drain control means when fluid conditions in said primary conduit reach a preselected condition.

33. The fluid purification apparatus of claim 14, said primary conduit including fluid drain control means and pressure limit valve control means operative to open said drain control means when fluid pressures in said primary conduit reach a preselected pressure level.

34. The fluid purification apparatus of claim 14, said primary circuit including fluid drain control means and pressure limit control means on both feed and product sides of said reverse osmosis means to selectively open each of said drain control means when preselected fluid pressure levels have been reached in the primary circuit on each side of said reverse osmosis means.

35. The fluid purification apparatus of claim 14, said primary circuit including fluid drain control means and a fluid current conductivity/resistivity monitor means operative to open said drain control means when fluid current conductivity/resistivity conditions in said primary circuit reach a preselected current level.

36. The fluid purification apparatus of claim 14, said primary conduit including fluid drain control means, and a fluid current conductivity/resistivity monitor means operative to open said drain control means when fluid current conductivity/resistivity conditions in said primary conduit reach a preselected current level;

and means to render said current conductivity/resistivity monitor means inoperative with respect to such drain control means when said secondary flow loop conduit is connected to said primary conduit in by-pass global loop relation to said reverse osmosis means.

37. The fluid purification apparatus of claim 14, said primary flow conduit including pressure restrictive means on said feed side of said reverse osmosis means to permit use of osmotically inactive fluids in said purification apparatus.

38. The fluid purification apparatus of claim 14, said primary flow conduit including pressure restrictive means between said feed side of said reverse osmosis means and said means connectable to said primary conduit to selectively introduce separate treating fluids.

39. A fluid purification apparatus comprising:

a primary flow conduit having spaced upstream fluid feed inlet means and downstream fluid product outlet means;

a reverse osmosis means disposed in said primary flow conduit between said fluid feed inlet means and said fluid product outlet means to include a feed side and a product side;

said primary flow conduit successively including downstream of said feed inlet means and before said reverse osmosis means, a carbon treating tank, a rinse control valve having a flow control restrictor parallel thereto, a prefilter, and a recirculating valve;

said primary flow conduit further including solvent drain control means and pressure limit control means on both feed and product sides of said reverse osmosis means to selectively open each of said drain control means when preselected fluid pressure levels have been reached in the primary circuit on each side of said reverse osmosis means and also including a conductivity/resistivity monitor means on said product side of said reverse osmosis means to open said drain control means when fluid current conductivity/resistivity conditions in said primary circuit reach a preselected level;

pump means positioned in communicative relation with said primary conduit as part of a secondary nested closed loop treating conduit nested in parallel relation with said primary conduit before said recirculating valve and said feed side of said reverse osmosis means;

treatment means communicating with said primary conduit through quick connect fittings on opposite sides of said recirculating valve, said treatment means including a vented treating fluid container having inlet and outlet conduits communicating with said primary flow conduit through said quick connect fittings and further including an inlet sensing and control valve sized to provide a preselected flow restriction and an outlet check valve in said container to regulate flow of fluid through said container to said primary conduit and through said drain control means in accordance with fluid level in said container; and

,

a secondary flow global loop conduit having quick connect fittings, at opposed ends thereof connectable to primary conduit fittings to extend parallel said primary flow conduit in by-pass relation to said reverse osmosis means to communicate directly between said product outlet means and said feed inlet means of said primary conduit and with said treatment means to flush said reverse osmosis means when a separate chemical treating fluid is selectively introduced into said treatment means, said primary flow conduit having quick connect fittings upstream said feed side of said reverse osmosis means and said prefilter and downstream said conductivity/resistivity monitor means on said product side of said reverse osmosis means to cooperate with quick connect fittings of said secondary flow loop conduit to allow placing of said secondary global loop conduit in by-pass relation to said reverse osmosis means, said quick connect fittings in said global loop including means to render said current conductivity/resistivity detection means inoperative with respect to drain when said secondary flow loop conduit is connected to said primary conduit in by-pass relation to said reverse osmosis means.