Method of Treating Water by Ballasted Flocculation/Settling, Which Includes a Continuous Measurement of the Ballast, and Corresponding Installation

• US 20090308815A1
• Filed: 07/25/2007
• Published: 12/17/2009
• Est. Priority Date: 08/01/2006
• Status: Active Grant

• Current Assignee: Veolia Water Solutions & Technologies Support
• Original Assignee: OTV S.A. (Veolia Environnement SA)
• Inventors: Ursel, Valery, Guillot, Sonia, Sauvignet, Philippe, Beaudet, Jean-Francois
• Granted Patent: US 8,092,688 B2
• Time in Patent Office: Days
• US Class Current: 210/709
• CPC Class Codes: B01D 21/0018 provided with a pump mounted in or on a settling tank
• CPC Class Codes: B01D 21/003 Sedimentation tanks provided with a plurality of compartments separated by a partition wall B01D21/0039 takes precedence
• CPC Class Codes: B01D 21/0045 Plurality of essentially parallel plates
• CPC Class Codes: B01D 21/0057 with counter-current flow direction of liquid and solid particles
• CPC Class Codes: B01D 21/08 provided with flocculating compartments
• CPC Class Codes: B01D 21/2444 Discharge mechanisms for the classified liquid
• CPC Class Codes: B01D 21/245 Discharge mechanisms for the sediments
• CPC Class Codes: B01D 21/2488 bringing about a partial recirculation of the liquid, e.g. for introducing chemical aids
• CPC Class Codes: B01D 21/32 Density control of clear liquid or sediment, e.g. optical control ; Control of physical properties
• CPC Class Codes: B01D 21/34 Controlling the feed distribution; Controlling the liquid level ; Control of process parameters
• CPC Class Codes: C02F 1/008 Control or steering systems not provided for elsewhere in subclass C02F
• CPC Class Codes: C02F 1/52 by flocculation or precipitation of suspended impurities C02F1/463 takes precedence
• CPC Class Codes: C02F 1/5281 Installations for water purification using chemical agents
• CPC Class Codes: C02F 1/56 Macromolecular compounds
• CPC Class Codes: C02F 2305/12 Inert solids used as ballast for improving sedimentation C02F3/1226 takes precedence
• CPC Class Codes: Y02W 10/37 using solar energy

Abstract

A method for treating water in a ballasted flocculation system comprises directing water into a ballasted flocculation zone and adding ballast and a flocculation reagent to the water to form a water-floc mixture. The water-floc mixture is directed into a settling zone to form treated water and sludge containing ballast. The ballast is then directed to a recirculation line where the ballast is recirculated to the ballasted flocculation zone. The method further includes determining the ballast concentration and comparing the ballast concentration with a predetermined threshold value. The rate at which ballast is recirculated to the ballasted flocculation zone is adjusted based on the determined ballast concentration and the predetermined threshold value. A ballasted flocculation system for treating water comprises a ballasted flocculation zone, a water inlet for directing water into the ballasted flocculation zone, and a flocculation reagent inlet for directing flocculation reagent into the ballasted flocculation zone. The system includes a settling zone for separating treated water from sludge containing ballast and a recirculation line for recirculating ballast from the settling zone to the ballasted flocculation zone. A first ballast inlet is operatively connected to the recirculation line for directing ballast into the ballasted flocculation zone. Finally, the system includes a sensor for measuring a parameter of ballast in the system.

Claims

1-21. -21. (canceled)

22. A method for treating water in a ballasted flocculation system comprising:

directing water into a ballasted flocculation zone;

adding ballast and a flocculation reagent to the water to form a water-floc mixture;

directing the water-floc mixture into a settling zone to form treated water and sludge containing ballast;

directing ballast to a recirculation line and recirculating ballast to the ballasted flocculation zone;

determining the concentration of ballast in the ballasted flocculation system;

comparing the concentration of ballast in the ballasted flocculation system with a predetermined threshold value; and

adjusting the ballast concentration in the ballasted flocculation system based on the determined ballast concentration and the predetermined threshold value.

23. The method of claim 22 further comprising adjusting the rate at which ballast is recirculated to the ballasted flocculation system based on the determined ballast concentration and the predetermined threshold value.

24. The method of claim 22 further comprising adding additional ballast from a holding zone to the ballasted flocculation system based on the determined ballast concentration and the predetermined threshold value.

25. The method of claim 22 further comprising measuring the ballast concentration in the recirculation line.

26. The method of claim 22 further comprising maintaining a substantially constant ballast concentration in the ballasted flocculation zone.

27. The method of claim 26 wherein the ballast concentration is maintained between approximately 1 kg/m³ to approximately 20 kg/m³.

28. The method of claim 27 wherein the ballast concentration is maintained between approximately 3 kg/m³ to approximately 10 kg/m³.

29. The method of claim 22 further comprising:

pumping ballast through the recirculation line; and

adjusting the rate at which ballast is pumped through the recirculation line such that the ballast concentration in the ballasted flocculation zone is generally maintained at a selected level.

30. The method of claim 25 further comprising sensing a parameter of the ballast in the ballasted flocculation system with an ultrasound sensor and determining the concentration of the ballast in the recirculation line based on the sensed parameter.

31. The method of claim 25 wherein the ballasted flocculation system includes a hydrocyclone having an overflow and an underflow and the method further comprises sensing a parameter of the ballast in the underflow of the hydrocyclone.

32. The method of claim 22 further comprising calculating the loss of ballast in the ballasted flocculation zone over time.

33. The method of claim 32 further comprising calculating the instantaneous loss of ballast in the ballasted flocculation zone over time.

34. The method of claim 32 further comprising adding additional ballast from a holding zone to the ballasted flocculation zone based on the calculated loss of ballast in the ballasted flocculation zone.

35. The method of claim 22 further comprising triggering an alarm indicating that the ballast concentration in the ballasted flocculation zone is either higher or lower than the predetermined threshold value.

36. The method of claim 22 wherein the settling zone includes a scraper and the method further comprises adjusting the speed of the scraper such that the ballast concentration in the ballasted flocculation zone is generally maintained at a selected level.

37. A ballasted flocculation system for treating water comprising:

a ballasted flocculation zone;

a water inlet for directing water into the ballasted flocculation zone;

a flocculation reagent inlet for directing flocculation reagent into the ballasted flocculation zone;

a settling zone disposed downstream from the ballasted flocculation zone for separating treated water from sludge containing ballast;

a first recirculation line for recirculating ballast from the settling zone to the ballasted flocculation zone;

a first ballast inlet operatively connected to the recirculation line for directing recirculated ballast into the ballasted flocculation zone;

a sensor for measuring a parameter of ballast in the ballasted flocculation system that is correlated to the ballast concentration in the ballasted flocculation system; and

a flow controller in the first recirculation line for varying the flow of ballast so as to generally control the ballast concentration in the ballasted flocculation zone.

38. The system of claim 37 further comprising:

a second recirculation line for recirculating ballast from the settling zone directly to the ballasted flocculation zone; and

a flow controller in the second recirculation line for varying the flow of ballast so as to generally control the ballast concentration in the ballasted flocculation zone.

39. The system of claim 37 wherein the first ballast inlet is operatively connected to a separator that separates ballast from sludge.

40. The system of claim 37 further comprising a second ballast inlet for directing additional ballast from a holding zone into the ballasted flocculation zone.

41. The system of claim 37 wherein the sensor is disposed on the first recirculation line and measures the parameter of the ballast passing through the recirculation line.

42. The system of claim 39 wherein the separator is a hydrocyclone having an underflow and an overflow;

and wherein the sensor is disposed in the underflow of the hydrocyclone and measures the parameter of the ballast in the underflow.

43. The system of claim 37 wherein the sensor is submerged in the ballasted flocculation zone and measures the parameter of the ballast in the ballasted flocculation zone.

44. The system of claim 37 wherein the sensor is an effect mass flowmeter sensor.

45. The system of claim 37 wherein the sensor is an ultrasound sensor.

46. The system of claim 37 wherein the sensor is an acoustic sensor.

47. The system of claim 46 wherein the sensor is a piezolelectric sensor.

48. The system of claim 37 wherein the sensor is an infrared absorption sensor.

49. The system of claim 48 wherein the infrared sensor measures the concentration of suspended solids in the concentration range of 0.001 to 50 g/l.

50. The system of claim 37 further comprising an alarm that indicates that the ballast concentration in the ballasted flocculation zone is either higher or lower than the predetermined threshold value.

51. The system of claim 37 further comprising a pump for pumping the ballast through the first recirculation line.

52. The system of claim 37 wherein the flow controller is a pump.

53. A method for treating water in a ballasted flocculation system comprising:

directing water into a ballasted flocculation zone;

adding ballast and a flocculation reagent to the ballasted flocculation zone to form a water-floc mixture;

directing the water-floc mixture into a settling zone to form treated water and sludge containing ballast;

continuously measuring the concentration of ballast in the ballasted flocculation system;

comparing the measured concentration of ballast in the ballasted flocculation system with a predetermined threshold value;

pumping the sludge containing ballast from the settling zone to a separator through a first recirculation line, separating the ballast from the sludge, and directing the ballast from the separator to the ballasted flocculation zone or directly recirculating the sludge containing ballast from the settling zone through a second recirculation line to the ballasted flocculation zone;

determining the flow rate of the ballast in the ballasted flocculation system in either the first or the second recirculation line;

comparing the measured concentration of ballast in the ballasted flocculation system with a predetermined threshold value; and

adjusting the flow rate of the ballast in either the first or second recirculation line based on the measured ballast concentration and the predetermined threshold value to maintain a predetermined concentration of ballast in the ballasted flocculation zone.