Method for treating wastewater

• US 7,648,638 B2
• Filed: 12/21/2004
• Issued: 01/19/2010
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Veolia Water Solutions & Technologies Support
• Original Assignee: OTV S.A.
• Inventors: Ursel, Valery, Essemiani, Karim
• Primary Examiner(s): Hruskoci; Peter A
• Application Number:
  US10/583,802
• Publication Number:
  US 20070114184A1
• Time in Patent Office: 1,855 Days
• Field of Search: 210/711
• US Class Current: 210/712
• CPC Class Codes: B01D 21/0045 Plurality of essentially parallel plates
• CPC Class Codes: B01D 21/01 using flocculating agents for purifying water C02F1/52; for liquid radioactive waste G21F9/10
• CPC Class Codes: B01D 21/02 Settling tanks with single outlets for the separated liquid
• CPC Class Codes: B01D 21/08 provided with flocculating compartments
• CPC Class Codes: B01D 21/20 Driving mechanisms
• CPC Class Codes: B01D 21/2405 Feed mechanisms for settling tanks
• CPC Class Codes: B01D 21/2444 Discharge mechanisms for the classified liquid
• CPC Class Codes: B03D 1/1412 with baffles, e.g. at the wall for redirecting settling solids
• CPC Class Codes: B03D 1/16 with impellers; Subaeration machines mixing gases or vapours with liquids B01F23/20
• CPC Class Codes: C02F 1/24 by flotation C02F1/465 takes precedence
• CPC Class Codes: C02F 1/5281 Installations for water purification using chemical agents
• CPC Class Codes: C02F 2301/024 Turbulent
• CPC Class Codes: C02F 2305/12 Inert solids used as ballast for improving sedimentation C02F3/1226 takes precedence

Abstract

A method and apparatus for treating wastewater. The apparatus comprises a reactor having a flow channel generally centrally located in a reactor and immersed in the water or wastewater in the reactor. An agitator is disposed within the flow channel and induces water or wastewater to enter the open upper end thereof and to move downwardly through the flow channel where the water or wastewater is discharged via a flow divider. A reagent is injected into the water or wastewater and the agitator within the flow channel serves to mix the reagent with the water or wastewater passing therethrough and in the process causes at least a slightly turbulent and downward axial flow through the flow channel.

Claims

1. A method of treating water or wastewater in a system including a reactor, a vertical flow channel disposed in the reactor, and a separator, comprising:

a. adding a flocculant to the water or wastewater;

b. directing the water or wastewater into an open upper end of the flow channel immersed in the water or wastewater in the reactor, down through the flow channel, out a lower end of the flow channel and upwardly outside of the flow channel and through the reactor;

c. continuously recycling the water or wastewater by directing the water or wastewater into the upper open end of the flow channel, downwardly through the flow channel, out the lower end of the flow channel, upwardly outside of the flow channel and through the reactor, and back into the open upper end of the flow channel;

d. mixing the flocculant and water or wastewater as the water or wastewater passes downwardly through the flow channel and wherein the mixing of the flocculant with the water or wastewater forms a flocculated mixture including flocs; and

e directing at least some of the flocculated mixture to the separator and separating clarified effluent from sludge which contains the flocs.

2. The method of claim 1 including continuously recirculating the flocculated mixture from the reactor downwardly through the immersed flow channel.

3. The method of claim 1 wherein an agitator is disposed in the flow channel, and the method includes agitating the water or wastewater in the flow channel so as to give rise to an axial downward flow of the water or wastewater.

4. The method of claim 1 including dividing the flow of the water or wastewater being discharged from the lower end of the flow channel.

5. The method of claim 1 including directing an inlet flow of water or wastewater into the reactor and maintaining a flow rate through the flow channel greater than the flow rate of inlet water or wastewater.

6. The method of claim 1 including agitating the water or wastewater passing through the flow channel, and wherein the agitation within the flow channel is more intense than agitation occurring outside the flow channel.

7. The method of claim 1 wherein the flow channel is disposed generally centrally within the reactor, and wherein the reactor includes an inlet and outlet disposed such that substantial portions of the water or wastewater to be treated is required to be passed through the general central area of the reactor.

8. The method of claim 1 including agitating the water or wastewater at generally a mid height in the flow channel resulting in a downward turbulent axial flow in the flow channel.

9. The method of claim 1 including dividing the flow of the flocculated mixture being discharged from the lower end of the flow channel.

10. The method of claim 9 including positioning a flow divider adjacent the outlet end of the flow channel for dividing the flow of the flocculated mixture.

11. The method of claim 1 wherein the reactor includes a surrounding wall structure, and the flow channel is disposed inwardly and in spaced apart relationship to at least a substantial portion of the surrounding wall structure of the reactor, and wherein the bottom of the flow channel is located from the bottom of the reactor a distance of approximately ⅓

to ⅔

of the average width of the flow channel.

12. The method of claim 11 wherein the top of the flow channel is located a distance of approximately ⅓

to ⅔

of the average width of the flow channel under the surface of the water or wastewater in the reactor.

13. The method of claim 1 wherein the flow channel is disposed generally centrally within the reactor, and wherein the reactor includes an inlet and outlet disposed with respect to each other so as to generally require the water or wastewater to be treated to move through the flow channel during the course of treatment.

14. The method of claim 1 wherein the flocculating agent is introduced upstream of the reactor or is introduced into the reactor.

15. The method of claim 14 wherein the flocculant is introduced between an inlet to the reactor and the open upper end of the flow channel.

16. The method of claim 1 including introducing the flocculant into a central area of the reactor.

17. The method of claim 1 wherein at least a portion of the flocculant is injected into the reactor generally coaxially with the flow channel.

18. The method of claim 1 including mixing an insoluble granular material with the water or wastewater.

19. The method of claim 18 including mixing the coagulant with the water or wastewater to be treated.

20. The method of claim 1 including mixing a coagulant with the water or wastewater to be treated.

21. The method of claim 1 wherein the separator comprises a sedimentation tank and wherein the flocs of the flocculated mixture settle in the sedimentation tank.

22. The method of claim 1 including agitating the water or wastewater with an agitator in the flow channel to cause the flow to move axially down through the flow channel, and engaging the downward flowing water or wastewater with a flow divider and dividing the flow after which the water or wastewater moves upwardly in the reactor and outside of the flow channel.

23. The method of claim 22 wherein agitation in the flow channel causes the water or wastewater to be relatively more turbulent in the flow channel than outside the flow channel.

24. The method of claim 1 wherein the flow channel is an elongated conduit having a wall structure that constrains the water or wastewater entering the open top thereof to move downwardly through the entire conduit and to be discharged out the lower open end thereof.

25. The method of claim 1 including an agitator disposed in the flow channel between the upper and lower ends and agitating the water or wastewater as the water or wastewater flows downwardly through the flow channel such that the flow of the water or wastewater through the flow channel is relatively more turbulent than the flow of water or wastewater outside of the flow channel;

and engaging the water or wastewater in the vicinity of the lower end of the flow channel with a structure that causes the flow of water or wastewater leaving the flow channel and moving upwardly in the reactor to be less turbulent than in the flow channel.

31. The method of claim 1, wherein both the flow channel and reactor include a horizontal width and wherein the horizontal width of the flow channel is approximately 40% to approximately 60% of the horizontal width of the reactor.

32. The method of claim 1, wherein the reactor includes an inlet and an outlet and wherein the flow rate of water or wastewater passing through the flow channel is approximately 1 to approximately 20 times the flow rate of the water or wastewater passing out the outlet of the reactor.

26. A method of mixing a flocculant with water or wastewater in a water or wastewater treatment system including a reactor and a vertical flow channel disposed in the reactor, comprising:

a. adding a flocculant to the water or wastewater;

b. directing the water or wastewater into an open upper end of the flow channel immersed in the water or wastewater in the reactor and moving the water or wastewater downwardly through the flow channel, out the lower end of the flow channel, and upwardly outside the flow channel and through the reactor;

c. as the water or wastewater moves downwardly through the flow channel, mixing the flocculant with the water or wastewater;

d. wherein an agitator is disposed in the flow channel between the upper and lower ends thereof, and the method includes driving the agitator and causing water or wastewater from the reactor to be induced into the open upper end of the flow channel and to be moved downwardly therethrough such that the water or wastewater is mixed with the flocculant to form a water or wastewater mixture as the water or wastewater moves downwardly through the flow channel; and

e. directing at least some of the water or wastewater mixture to a separator and clarifying the water or wastewater mixture.

27. The method of claim 26 including a flow divider disposed in the vicinity of the lower end of the flow channel and wherein the method includes dividing the flow of water or wastewater being discharged from the lower end of the flow channel.

28. The method of claim 26 wherein the agitator causes the water or wastewater passing downwardly through the flow channel to be at least slightly turbulent, and wherein the method entails engaging the water or wastewater being discharged from the flow channel so as to cause the water or wastewater moving upwardly through the reactor and outside of the flow channel to be less turbulent than the flow of water or wastewater through the flow channel.

29. The method of claim 28 including continuously recirculating water or wastewater from the reactor into the open upper end of the flow channel and downwardly through the flow channel where the water or wastewater is discharged therefrom and thereafter moves upwardly in the reactor outside of the flow channel.

30. The method of claim 26 wherein the agitator causes the water or wastewater passing through the flow channel to become at least slightly turbulent and to move downwardly in an axial flow pattern, and wherein the method entails engaging the flow of water or wastewater being discharged from the flow channel and dividing the flow of water or wastewater being discharged from the flow channel.

33. The method of claim 26 including continuously recirculating the water or wastewater by directing the water or wastewater into the upper open end of the flow channel, downwardly through the flow channel, and out the lower end of the flow channel, upwardly outside of the flow channel and through the reactor, and back into the open upper end of the flow channel.

34. The method of claim 26, wherein the flow channel is disposed generally centrally within the reactor, and wherein the reactor includes an inlet and outlet disposed such that substantial portions of the water or wastewater to be mixed with the flocculant is required to be passed through the general central area of the reactor.

35. The method of claim 26 including agitating the water or wastewater with the agitator in the flow channel to cause the flow to move axially down through the flow channel, and engaging the downward flowing water or wastewater with a flow divider and dividing the flow, after which the water or wastewater moves upwardly in the reactor and outside of the flow channel.

36. The method of claim 26, wherein the mixing of the flocculant with the water or wastewater forms a flocculated mixture including flocs;

and directing at least some of the flocculated mixture to a separator and separating clarified effluent from sludge which contains the flocs.

37. The method of claim 36 including dividing the flow of water or wastewater being discharged from the lower end of the flow channel.

38. The method of claim 37 including directing the water or wastewater through a flow divider disposed adjacent the lower end of the flow channel and dividing the flow of the flocculated mixture and directing at least a portion of the flocculated mixture upwardly outside of the flow channel and through the reactor and back into the open upper end of the flow channel.

39. A method of treating water or wastewater in a system including a reactor, a vertical flow channel disposed in the reactor, and a separator, comprising:

a. adding a flocculant to the water or wastewater;

b. directing the water or wastewater into an open upper end of the flow channel immersed in the water or wastewater in the reactor, down through the flow channel, out a lower end of the flow channel and upwardly outside of the flow channel and through the reactor;

c. mixing the flocculant and water or wastewater as the water or wastewater passes downwardly through the flow channel and wherein the mixing of the flocculant with the water or wastewater forms a flocculated mixture including flocs;

d. agitating the water or wastewater as the water or wastewater flows downwardly through the flow channel such that the flow of the water or wastewater through the flow channel is relatively more turbulent than the flow of water or wastewater outside of the flow channel, and engaging the water or wastewater in the vicinity of the lower end of the flow channel with a structure that causes the flow of water or wastewater leaving the flow channel and moving upwardly in the reactor to be less turbulent than in the flow channel, and recirculating the water or wastewater from the reactor into and downwardly through the flow channel; and

e. directing at least some of the flocculated mixture to the separator and separating clarified effluent from sludge which contains the flocs.

40. The method of claim 39 including continuously recirculating the flocculated mixture from the reactor downwardly through the immersed flow channel.

41. The method of claim 39 including dividing the flow of the water or wastewater being discharged from the lower end of the flow channel.

42. The method of claim 39 including directing an inlet flow of water or wastewater into the reactor and maintaining a flow rate through the flow channel greater than the flow rate of inlet water or wastewater.

43. The method of claim 39 wherein the flow channel is disposed generally centrally within the reactor, and wherein the reactor includes an inlet and outlet disposed such that substantial portions of the water or wastewater to be treated is required to be passed through the general central area of the reactor.

44. The method of claim 39 including positioning a flow divider adjacent the outlet end of the flow channel for dividing the flow of the flocculated mixture.

45. The method of claim 39 wherein the reactor includes a surrounding wall structure, and the flow channel is disposed inwardly and in spaced apart relationship to at least a substantial portion of the surrounding wall structure of the reactor, and wherein the bottom of the flow channel is located from the bottom of the reactor a distance of approximately ⅓

to ⅔

of the average width of the flow channel.