Method and apparatus for biological wastewater treatment

• US 6,616,845 B2
• Filed: 05/29/2001
• Issued: 09/09/2003
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: Aqwise-Wise Water Technologies Ltd.
• Original Assignee: Aqwise-Wise Water Technologies Ltd.
• Inventors: Levy, Eytan, Shechter, Ronen
• Primary Examiner(s): Upton, Christopher
• Application Number:
  US09/866,886
• Publication Number:
  US 20020179526A1
• Time in Patent Office: 833 Days
• Field of Search: 210/150, 210/151, 210/194, 210/195.1, 210/202, 210/220, 210/258, 210/616, 210/620, 210/629, 210/903
• US Class Current: 210/616
• CPC Class Codes: B01J 19/30 Loose or shaped packing elements, e.g. Raschig rings or Berl saddles, for pouring into the apparatus for mass or heat transfer
• CPC Class Codes: B01J 2219/30223 Cylinder
• CPC Class Codes: B01J 2219/30242 Star
• CPC Class Codes: B01J 2219/30466 Plastics
• CPC Class Codes: C02F 3/02 Aerobic processes
• CPC Class Codes: C02F 3/087 Floating beds with contact bodies having a lower density than water
• CPC Class Codes: C02F 3/10 Packings; Fillings; Grids packing elements in general B01J19/30, B01J19/32
• CPC Class Codes: C02F 3/223 using "air-lift"
• CPC Class Codes: Y02W 10/10 Biological treatment of water, waste water, or sewage

Abstract

A method and apparatus for retrofitting existing waste water treatment facilities having at least one existing basin including installing generally vertical partitions at spaced locations in the at least one existing basin in order to divide the at least one existing basin into a plurality of treatment stage regions, installing at least one air lift in each of the plurality of treatment stage regions, loading each treatment stage regions with a quantity of floatable porous particles, supplying waste water to at least one of the plurality of treatment stage regions and allowing the waste water, but generally not the particles, to flow from at least one of the plurality of treatment stage regions to at least another of the plurality of treatment stage regions and operating the at least one air lift in each of the plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with the floatable porous particles.

Claims

1. A method for retrofitting existing waste water treatment facilities having at least one existing basin comprising:

installing generally vertical partitions at spaced locations in said at least one existing basin in order to provide said at least one existing basin into a plurality of treatment stage regions;

installing at least one air lift in each of said plurality of treatment stage regions;

loading each of said plurality of treatment stage regions with a quantity of floatable porous particles;

supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions below at least one of said generally vertical partitions; and

operating said at least one air lift in each of said plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with said floatable porous particles,

wherein;

said at least one air lift comprises a series of air lifts arranged in multiple process stages;

said series of air lifts includes an initial air lift assembly and at least one intermediate air lift assembly at each of said multiple process stages;

said initial air lift assembly includes an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin;

said supplying comprises providing a continuous flow of water from an upstream side of said basin from a waste water inlet to a treated water outlet; and

said flow is an undulating flow and includes passage under said upstream partitions which is of relatively low volume and generally does not carry said floatable particles into said series of air lifts, thereby constraining said particles to reside outside of and between said series of air lifts.

2. A method according to claim 1 and wherein at least some of said vertical partitions are spaced from said bottom of said at least one basin in order to allow said waste water to flow thereunder between adjacent ones of said plurality of treatment stage regions.

3. A method according to claim 1 and wherein said at least one air lift comprises at least one air diffuser disposed underlying a peripheral enclosure which defines a column of water which is lifted by air diffusing upwardly from said at least one air diffuser therethrough.

4. A method according to claim 3 and wherein said peripheral enclosure comprises a cylindrical enclosure.

5. A method according to claim 3 and wherein said peripheral enclosure comprises a plurality of spaced generally vertical walls which extend between walls of the basin and are separated from the bottom of the basin.

6. A method according to claim 1 and wherein said floatable particles comprise porous plastic particles having a density lower than that of pure water.

7. A method according to claim 6 and wherein said particles have a specific gravity between 0.65 and 0.95.

8. A method according to claim 6 and wherein said particles have an irregular shape, whose largest dimension is generally between 4-10 mm.

9. A method according to claim 6 and wherein said particles have a total porosity exceeding 50%.

10. A method according to claim 6 and wherein said particles have a mean pore diameter of pores, whose diameter exceeds 10 microns, of about 20 microns.

11. A method according to claim 1 and wherein said generally vertical partitions divide said basin into between 4 and 12 process stages.

12. A method according to claim 1 and wherein said upstream partition extends fully from side to side of said basin.

13. A method according to claim 1 and wherein said initial air lift assembly also includes a downstream partition which extends fully from side to side of said basin but does not extend up to said water level.

14. A method according to claim 1 and wherein said intermediate air lift assembly includes an upstream partition which extends downwardly from a top location below said water level in said basin to a bottom location spaced from said bottom of said basin.

15. A method according to claim 1 and wherein said vertical partitions each extend fully from side to side of said basin.

16. A method according to claim 1 and wherein said installing also includes installing a final air lift assembly including an upstream partition which extends downwardly from a top location below said water level in said basin to a bottom location spaced from said bottom of said basin and extends fully from side to side of said basin.

17. A method according to claim 16 and wherein said final air lift assembly also includes a downstream partition which also extends fully from side to side of said basin and extends to a top location above said water level and closer to said bottom than does said upstream partition.

18. A method according to claim 17 and wherein said downstream partition is attached to a deflector plate which extends in an upstream direction from downstream partition at a location at said water level.

19. A method according to claim 1 and wherein:

said at least one air lift comprises a plurality of air lift assemblies each including upstream and downstream partitions;

a first plurality of air diffusers are disposed at said bottom of said basin intermediate upstream and downstream partitions of said plurality of air lift assemblies; and

a second plurality of air diffusers, lesser in number than said first plurality of air diffusers, are disposed at said bottom of said basin intermediate said plurality of air lift assemblies.

20. A method according to claim 19 and wherein said first plurality of air diffusers intermediate said upstream and downstream partitions of each air lift assembly causes water to flow upward between said upstream and downstream partitions of each air lift assembly.

21. A method according to claim 20 and wherein said second plurality of air diffusers intermediate said plurality of air lift assemblies allows water to flow downward.

22. A method according to claim 19 and also comprising controlling the flow velocity of water by controlling operation of said first and second pluralities of air diffusers.

23. A method according to claim 1 and wherein said loading comprises loading 10-40 percent of the volume of said basin with said particles in absence of water flow.

24. A method according to claim 1 and wherein said at least one air lift includes an adjustable angle deflector.

25. A method according to claim 1 and wherein said at least one air lift includes an integral curved downstream partition and deflector.

26. A method according to claim 1 and also comprising installing a denitrification unit in at least one of said plurality of treatment stage regions.

27. A method according to claim 26 and wherein said denitrification unit comprises a plurality of axial pumps which provide lift generally without an air flow, thereby to provide an anoxic de-nitrification process.

28. A method according to claim 1 and wherein said at least one air lift comprises an array of air lifts and wherein said array of air lifts comprises a multiplicity of cylindrical air lifts arranged in said plurality of treatment stage regions and separated by said vertical partitions which extend from a bottom location which is spaced from a bottom of said basin by a first vertical separation.

29. A method according to claim 28 and wherein said cylindrical air lifts each comprise:

a hollow shaft which extends from a bottom location spaced from a bottom of said basin by a second vertical separation which exceeds said first separation;

a deflector which is disposed in spaced relationship over each hollow shaft and is disposed at said water level; and

at least one air diffuser which is disposed underlying each hollow shaft to provide an air lift therethrough, thereby causing water to flow into said hollow shafts and upwardly through said hollow shafts, said deflectors causing said water exiting said tops of said hollow shafts to move sideways and downwardly.

30. A method according to claim 29 and also comprising:

a plurality of air diffusers disposed immediately upstream of each said vertical partition for providing control of particle movement and prevention of particle migration.

31. A method according to claim 1 and wherein said operating produces fluidization of said particles.

32. A method according to claim 1 and wherein said operating is operative, when said particles become heavily coated with biomass, to cause said particles sometimes to enter said at least one air lift and to be sloughed of some of said biomass as they are propelled upwards by action of said at least one air lift.

33. A method for retrofitting existing waste water treatment facilities having at least one existing basin comprising:

installing generally vertical partitions at spaced locations in said at least one existing basin in order to divide said at least one existing basin into a plurality of treatment stage regions;

installing at least one air lift in each of said plurality of treatment stage regions;

loading each of said plurality of treatment stage regions with a quantity of floatable porous particles;

supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions; and

operating said at least one air lift in each of said plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with said floatable porous particles,

and wherein said at least one air lift comprises a series of air lifts arranged in multiple process stages,

and wherein said series of air lifts includes an initial air lift assembly and at least one intermediate air lift assembly at each of said multiple process stages,

and wherein said initial air lift assembly includes an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin,

and wherein said upstream partition is attached to a deflector which extends in a downstream direction from said upstream partition at said water level.

34. A method for retrofitting existing waste water treatment facilities having at least one existing basin comprising:

installing generally vertical partitions at spaced locations in said at least one existing basin in order to divide said at least one existing basin into a plurality of treatment stage regions;

installing at least one air lift in each of said plurality of treatment stage regions;

loading each of said plurality of treatment stage regions with a quantity of floatable porous particles;

supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions; and

operating said at least one air lift in each of said plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with said floatable porous particles,

and wherein said at least one air lift comprises a series of air lifts arranged in multiple process stages,

and wherein said series of air lifts includes an initial air lift assembly and at least one intermediate air lift assembly at each of said multiple process stages,

and wherein said at least one intermediate air lift assembly comprises an upstream partition separated from a deflector plate which extends in a downstream direction from said upstream partition at a water level in said basin.

35. A method according to claim 34 and wherein said at least one intermediate air lift assembly also includes a downstream partition which does not extend up to said water level or as close to a bottom of said basin as does said upstream partition.

36. A method for waste water treatment employing at least one basin comprising:

installing generally vertical partitions at spaced locations in said at least one basin in order to divide said at least one basin into a plurality of treatment stage regions;

installing at least one air lift in each of said plurality of treatment stage regions;

loading each of said plurality of treatment stage regions with a quantity of floatable porous particles;

supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions below at least one of said generally vertical partitions; and

operating said at least one air lift in each of said plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with said floatable porous particles,

wherein;

said at least one air lift comprises a series of air lifts arranged in multiple process stages;

said series of air lifts includes an initial air lift assembly and at least one intermediate air lift assembly at each of said multiple process stages;

said initial air lift assembly includes an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin;

said supplying comprises providing a continuous flow of water from an upstream side of said basin from a waste water inlet to a treated water outlet; and

said flow is an undulating flow and includes passage under said upstream partitions which is of relatively low volume and generally does not carry said floatable particles into said series of air lifts, thereby constraining said particles to reside outside of and between said series of air lifts.

37. A method according to claim 36 and wherein at least some of said vertical partitions are spliced from said bottom of said at least one basin in order to allow said waste water to flow thereunder between adjacent ones of said plurality of treatment stage regions.

38. A method according to claim 36 and wherein said at least one air lift comprises at least one air diffuser disposed underlying a peripheral enclosure which defines a column of water which is lifted by air diffusing upwardly from said at least one air diffuser therethrough.

39. A method according to claim 38 and wherein said peripheral enclosure comprises a cylindrical enclosure.

40. A method according to claim 38 and wherein said peripheral enclosure comprises a plurality of spaced generally vertical walls which extend between walls of the basin and are separated from the bottom of the basin.

41. A method according to claim 36 and wherein said floatable particles comprise porous plastic particles having a density lower than that of pure water.

42. A method according to claim 41 and wherein said particles have a specific gravity between 0.65 and 0.95.

43. A method according to claim 41 and wherein said particles have an irregular shape, whose largest dimension is generally between 4-10 mm.

44. A method according to claim 41 and wherein said particles have a total porosity exceeding 50%.

45. A method according to claim 41 and wherein said particles have a mean pore diameter of pores, whose diameter exceeds 10 microns, of about 20 microns.

46. A method according to claim 36 and wherein said generally vertical partitions divide said basin into between 4 and 12 process stages.

47. A method according to claim 36 and wherein said upstream partition extends fully from side to side of said basin.

48. A method according to claim 36 and wherein said initial air lift assembly also includes a downstream partition which extends fully from side to side of said basin but does not extend up to aid water level.

49. A method according to claim 36 and wherein said intermediate air lift assembly includes an upstream partition which extends downwardly from a top location below said water level in said basin to a bottom location spaced from said bottom of said basin.

50. A method according to claim 36 and wherein said vertical partitions each extend fully from side to side of said basin.

51. A method according to claim 36 and wherein said installing also includes installing a final air lift assembly including an upstream partition which extends downwardly from a top location below the water level in said basin to a bottom location spaced from said bottom of said basin and extends fully from side to side of said basin.

52. A method according to claim 51 and wherein said final air lift assembly also includes a downstream partition which also extends filly from side to side of said basin and extends to a top location above said water level and closer to said bottom than does said upstream partition.

53. A method according to claim 52 and wherein said downstream partition is attached to a deflector plate which extends in an upstream direction from downstream partition at a location at the basin'"'"'s water level.

54. A method according to claim 36 and wherein:

said at least one air lift comprises a plurality of air lift assemblies each including upstream and downstream partitions;

a first plurality of air diffusers are disposed at said bottom of said basin intermediate upstream and downstream partitions of said plurality of air lift assemblies; and

a second plurality of air diffusers, lesser in number than said first plurality of air diffusers, are disposed at said bottom of said basin intermediate said plurality of air lift assemblies.

55. A method according to claim 54 and wherein said first plurality of air diffusers intermediate said upstream and downstream partitions of each air lift assembly causes water to flow upward between said upstream and downstream partitions of each air lift assembly.

56. A method according to claim 55 and wherein said second plurality of air diffusers intermediate said plurality of air lift assemblies allows water to flow downward.

57. A method according to claim 54 and also comprising controlling the flow velocity of water by controlling operation of said first and second pluralities of air diffusers.

58. A method according to claim 36 and wherein said loading comprises loading 10-40 percent of the volume of said basin with said particles in absence of water flow.

59. A method according to claim 36 and wherein said at least one air lift includes an adjustable angle deflector.

60. A method according to claim 36 and wherein said at least one air lift includes an integral curved downstream partition and deflector.

61. A method according to claim 36 and also comprising installing a denitrification unit in at least one of said plurality of treatment stage regions.

62. A method according to claim 61 and wherein said denitrification unit comprises a plurality of axial pumps which provide lift generally without an air flow, thereby to provide an anoxic de-nitrification process.

63. A method according to claim 36 and wherein said at least one air lift comprises an array of air lifts and wherein said array of air lifts comprises a multiplicity of cylindrical air lifts arranged in said plurality of treatment stage regions and separated by said vertical partitions which extend from a bottom location which is spaced from a bottom of said basin by a first vertical separation.

64. A method according to claim 63 and wherein said cylindrical air lifts each comprise:

a hollow shaft which extends from a bottom location spaced from a bottom of said basin by a second vertical separation which exceeds said first separation;

a deflector which is disposed in spaced relationship over each hollow shaft and is disposed at the basin'"'"'s water level; and

at least one air diffuser which is disposed underlying each hollow shaft to provide an air lift therethrough, thereby causing water to flow into said hollow shafts and upwardly through said hollow shafts, said deflectors causing said water exiting top portions of said hollow shafts to move sideways and downwardly.

65. A method according to claim 64 and also comprising:

a plurality of air diffusers disposed immediately upstream of each said vertical partition for providing control of particle movement and prevention of particle migration.

66. A method according to claim 36 and wherein said operating produces fluidization of said particles.

67. A method according to claim 36 and wherein said operating is operative, when said particles become heavily coated with biomass, to cause said particles sometimes to enter said at least one air lift and to be sloughed of some of said biomass as they are propelled upward by action of said at least one air lift.

68. A method for waste water treatment employing at least one basin comprising:

installing generally vertical partitions at spaced locations in said at least one basin in order to divide said at least one basin into a plurality of treatment stage regions;

installing at least one air lift in each of said plurality of treatment stage regions;

loading each of said plurality of treatment stage regions with a quantity of floatable porous particles;

supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions; and

operating said at least one air lift in each of said plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with said floatable porous particles,

and wherein said at least one air lift comprises a series of air lifts arranged in multiple process stages,

and wherein said series of air lifts includes an initial air lift assembly and at least one intermediate air lift assembly at each of said multiple process stages,

and wherein said initial air lift assembly includes an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin,

and wherein said upstream partition is attached to a deflector which extends in a downstream direction from said upstream partition at said water level.

69. A method for waste water treatment employing at least one basin comprising:

installing generally vertical partitions at spaced locations in said at least one basin in order to divide said at least one basin into a plurality of treatment stage regions;

installing at least one air lift in each of said plurality of treatment stage regions;

loading each of said plurality of treatment stage regions with a quantity of floatable porous particles;

supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions; and

operating aid at least one air lift in each of said plurality of treatment stage regions to provide aerobic waste water flow therein in operative engagement with said floatable porous particles,

and wherein said at least one air lift comprises a series of air lifts arranged in multiple process stages,

and wherein said series of air lifts includes an initial air lift assembly and at least one intermediate air lift assembly at each of said multiple process stages,

and wherein said at least one intermediate air lift assembly comprises an upstream partition separated from a deflector plate which extends in a downstream direction from said upstream partition at a water level in said basin.

70. A method according to claim 69 and wherein said at least one intermediate air lift assembly also includes a downstream partition which does not extend up to said water level or as close to a bottom of said basin as does said upstream partition.

71. Retrofitted waste water treatment apparatus comprising:

at least one existing basin;

generally vertical partitions located at spaced locations in said at least one existing basin in order to divide said at least one existing basin into a plurality of treatment stage regions;

at least one air lift, located in each of said plurality of treatment stage regions, comprising a series of air lifts, arranged in each of multiple process stages, including;

an initial air lift assembly including an upstream partition which extends downwardly from top location above a water level in said existing basin to a bottom location spaced from a bottom of said existing basin; and

at least on intermediate air lift assembly; and

a quantity of floatable porous particles loaded into each of said plurality of treatment stage regions, whereby supplying waste water from an upstream side of said existing basin, by providing a continuous flow of water from a waste water inlet to a treated water outlet, to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions below at leas one of said generally vertical partitions and operating said at least one air lift in each of said plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with said floatable porous particles,

wherein said flow is an undulating flow and includes passage under said upstream partitions which is of relatively low volume and generally does not carry said floatable particles into said series of air lifts, thereby constraining said particles to reside outside of and between said series of air lifts.

72. Apparatus according to claim 71 and wherein at least some of said vertical partitions are spaced from said bottom of said at least one basin in order to allow said waste water to flow thereunder between adjacent ones of said plurality of treatment stage regions.

73. Apparatus according to claim 71 and wherein said at least one air lift comprises at least one air diffuser disposed underlying a peripheral enclosure which defines a column of water which is lifted by air diffusing upwardly from said at least one air diffuser therethrough.

74. Apparatus according to claim 73 and wherein said peripheral enclosure comprises a cylindrical enclosure.

75. Apparatus according to claim 73 and wherein said peripheral enclosure comprises a plurality of spaced generally vertical walls which extend between walls of the basin and are separated from the bottom of the basin.

76. Apparatus according to claim 71 and wherein said floatable particles comprise porous plastic particles having a density lower than that of pure water.

77. Apparatus according to claim 76 and wherein said particles have a specific gravity between 0.65 and 0.95.

78. Apparatus according to claim 76 and wherein said particles have an irregular shape, whose largest dimension is generally between 4-10 mm.

79. Apparatus according to claim 76 and wherein said particles have a total porosity exceeding 50%.

80. Apparatus according to claim 76 and wherein said particles have a mean pore diameter of pores, whose diameter exceeds 10 microns, of about 20 microns.

81. Apparatus according to claim 71 and wherein said generally vertical partitions divide said basin into between 4 and 12 process stages.

82. Apparatus according to claim 71 and wherein said upstream partition extends fully from side to side of said basin.

83. Apparatus according to claim 71 and wherein said initial air lift assembly also includes a downstream partition which extends fully from side to side of said basin but does not extend up to said water level.

84. Apparatus according to claim 71 and wherein said intermediate air lift assembly includes an upstream partition which extends downwardly from a top location below said water level in said basin to a bottom location spaced from said bottom of said basin.

85. Apparatus according to claim 71 and wherein said vertical partitions each extend fully from side to side of said basin.

86. Apparatus according to claim 71 and wherein said installing also includes installing a final air lift assembly including an upstream partition which extends downwardly from a top location below said water level in said basin to a bottom location spaced from said bottom of said basin and extends fully from side to side of said basin.

87. Apparatus according to claim 86 and wherein said final air lift assembly also includes a downstream partition which also extends fully from side to side of said basin and extends to a top location above said water level and closer to said bottom than does said upstream partition.

88. Apparatus according to claim 87 and wherein said downstream partition is attached to a deflector plate which extends in an upstream direction from downstream partition at a location at said water level.

89. Apparatus according to claim 71 and wherein:

said at least one air lift comprises a plurality of air lift assemblies each including upstream and downstream partitions;

a first plurality of air diffusers are disposed at said bottom of said basin intermediate upstream and downstream partitions of said plurality of air lift assemblies; and

a second plurality of air diffusers, lesser in number than said first plurality of air diffusers, are disposed at said bottom of said basin intermediate said plurality of air lift assemblies.

90. Apparatus according to claim 89 and wherein said first plurality of air diffusers intermediate said upstream and downstream partitions of each air lift assembly causes water to flow upward between said upstream and downstream partitions of each air lift assembly.

91. Apparatus according to claim 90 and wherein said second plurality of air diffusers intermediate said plurality of air lift assemblies allows water to flow downward.

92. Apparatus according to claim 89 and also comprising controlling the flow velocity of water by controlling operation of said first and second pluralities of air diffusers.

93. Apparatus according to claim 71 and wherein said floatable porous particles fill 10-40 percent of the volume of said basin in the absence of water flow.

94. Apparatus according to claim 71 and wherein said at least one air lift includes an adjustable angle deflector.

95. Apparatus according to claim 71 and wherein said at least one air lift includes an integral curved downstream partition and deflector.

96. Apparatus according to claim 71 and also comprising installing a denitrification unit in at least one of said plurality of treatment stage regions.

97. Apparatus according to claim 96 and wherein said denitrification unit comprises a plurality of axial pumps which provide lift generally without an air flow, thereby to provide an anoxic de-nitrification process.

98. Apparatus according to claim 71 and wherein said at least one air lift comprises an array of air lifts and wherein said array of air lifts comprises a multiplicity of cylindrical air lifts arranged in said plurality of treatment stage regions and separated by said vertical partitions which extend from a bottom location which is spaced from a bottom of said basin by a first vertical separation.

99. Apparatus according to claim 98 and wherein said cylindrical air lifts each comprise:

a hollow shaft which extends from a bottom location spaced from a bottom of said basin by a second vertical separation which exceeds said first separation;

a deflector which is disposed in spaced relationship over each hollow shaft and is disposed at said water level; and

at least one air diffuser which is disposed underlying each hollow shaft to provide an air lift therethrough, thereby causing water to flow into said hollow shafts and upwardly through said hollow shafts, said deflectors causing said water exiting said tops of said hollow shafts to move sideways and downwardly.

100. Apparatus according to claim 99 and also comprising:

a plurality of air diffusers disposed immediately upstream of each said vertical partition for providing control of particle movement and prevention of particle migration.

101. Apparatus according to claim 71 and wherein said at least one air lift produces fluidization of said particles.

102. Apparatus according to claim 71 and wherein said at least one air lift is operative, when said particles become heavily coated with biomass, to cause said particles sometimes to enter said at least one air lift and to be sloughed of some of said biomass as they are propelled upwards by action of said at least one air lift.

103. Retrofitted waste water treatment apparatus comprising:

at least one existing basin;

generally vertical partitions located at spaced locations in said at least one existing basin in order to divide said at least one existing basin into a plurality of treatment stage regions;

at least one air lift, located in each of said plurality of treatment stage regions, comprising a series of air lifts arranged in each of multiple process stages, including;

an initial air lift assembly including an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin; and

at least one intermediate air lift assembly; and

a quantity of floatable porous particles loaded into each of said plurality of treatment stage regions, whereby supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions and operating said at least one air lift in each of said plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with said floatable porous particles,

and wherein said upstream partition is attached to a deflector which extends in a downstream direction from said upstream partition at said water level.

104. Retrofitted waste water treatment apparatus comprising:

at least one existing basin;

generally vertical partitions located at spaced locations in said at least one existing basin in order to divide said at least one existing basin into a plurality of treatment stage regions;

at least one air lift, located in each of said plurality of treatment stage regions, comprising a series of air lifts, arranged in each of multiple process stages, including;

an initial air lift assembly; and

at least one intermediate air lift assembly including an upstream partition separated from a deflector plate which extends in a downstream direction from said upstream partition at a water level in said basin; and

a quantity of floatable porous particles loaded into each of said plurality of treatment stage regions, whereby supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions and operating said at least one air lift in each of said plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with said floatable porous particles.

105. Apparatus according to claim 104 and wherein said at least one intermediate air lift assembly also includes a downstream partition which does not extend up to said water level or as close to a bottom of said basin as does said upstream partition.

106. Waste water treatment apparatus comprising:

at least one basin;

generally vertical partitions located at spaced locations in said at least one basin in order to divide said at least one basin into a plurality of treatment stage regions;

at least one/air lift, located in each of said plurality of treatment stage regions, comprising a series of air lifts, arranged in each of multiple process stages, including;

an initial air lift assembly including an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin; and

at least one intermediate air lift assembly; and

a quantity of floatable porous particles loaded into each of said plurality of treatment stage regions, whereby supplying waste water from an upstream side of said basin, by providing continuous flow of water from a waste water inlet to a treated water outlet, to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions below at least one of said generally vertical partitions and operating said at least one air lift in each of said plurality oft treatment stage regions provides aerobic waste water flow therein in operative engagement with said floatable porous particles,

wherein said flow is an undulating flow and includes passage under said upstream partitions which is of relatively low volume and generally does not carry said floatable particles into said series of air lifts, thereby constraining said particles to reside outside of and between said series of air lifts.

107. Apparatus according to claim 106 and wherein at least some of said vertical partitions are spaced from said bottom of said at least one basin in order to allow said waste water to flow thereunder between adjacent ones of said plurality of treatment stage regions.

108. Apparatus according to claim 106 and wherein said at least one air lift comprises at least one air diffuser disposed underlying a peripheral enclosure which defines a column of water which is lifted by air diffusing upwardly from said at least one air diffuser therethrough.

109. Apparatus according to claim 108 and wherein said peripheral enclosure comprises a cylindrical enclosure.

110. Apparatus according to claim 108 and wherein said peripheral enclosure comprises a plurality of spaced generally vertical walls which extend between walls of the basin and are separated from the bottom of the basin.

111. Apparatus according to claim 106 and wherein said floatable particles comprise porous plastic particles having a density lower than that of pure water.

112. Apparatus according to claim 111 and wherein said particles have a specific gravity between 0.65 and 0.95.

113. Apparatus according to claim 111 and wherein said particles have an irregular shape, whose largest dimension is generally between 4-10 mm.

114. Apparatus according to claim 111 and wherein said particles have a total porosity exceeding 50%.

115. Apparatus according to claim 111 and wherein said particles have a mean pore diameter of pores, whose diameter exceeds 10 microns, of about 20 microns.

116. Apparatus according to claim 106 and wherein said generally vertical partitions divide said basin into between 4 and 12 process stages.

117. Apparatus according to claim 106 and wherein said upstream partition extends fully from side to side of said basin.

118. Apparatus according to claim 106 and wherein said initial air lift assembly also includes a downstream partition which extends fully from side to side of said basin but does not extend up to said water level.

119. Apparatus according to claim 106 and wherein said intermediate air lift assembly includes an upstream partition which extends downwardly from a top location below said water level in said basin to a bottom location spaced from said bottom of said basin.

120. Apparatus according to claim 106 and wherein said vertical partitions each extend fully from side to side of said basin.

121. Apparatus according to claim 106 and wherein said installing also includes installing a final air lift assembly including an upstream partition which extends downwardly from a top location below the water level in said basin to a bottom location spaced from said bottom of said basin and extends fully from side to side of said basin.

122. Apparatus according to claim 121 and wherein said final air lift assembly also includes a downstream partition which also extends fully from side to side of said basin and extends to a top location above the water level and closer to said bottom than does said upstream partition.

123. Apparatus according to claim 122 and wherein said downstream partition is attached to a deflector plate which extends in an upstream direction from downstream partition at a location at the water level.

124. Apparatus according to claim 106 and wherein:

said at least one air lift comprises a plurality of air lift assemblies each including upstream and downstream partitions;

a first plurality of air diffusers are disposed at said bottom of said basin intermediate upstream and downstream partitions of said plurality of air lift assemblies; and

a second plurality of air diffusers, lesser in number than said first plurality of air diffusers, are disposed at said bottom of said basin intermediate said plurality of air lift assemblies.

125. Apparatus according to claim 124 and wherein said first plurality of air diffusers intermediate said upstream and downstream partitions of each air lift assembly causes water to flow upward between said upstream and downstream partitions of each air lift assembly.

126. Apparatus according to claim 125 and wherein said second plurality of air diffusers intermediate said plurality of air lift assemblies allows water to flow downward.

127. Apparatus according to claim 124 and also comprising controlling the flow velocity of water by controlling operation of said first and second pluralities of air diffusers.

128. Apparatus according to claim 106 and wherein said floatable porous particles fill 10-40 percent of the volume of said basin in the absence of water flow.

129. Apparatus according to claim 106 and wherein said at least one air lift includes an adjustable angle deflector.

130. Apparatus according to claim 106 and wherein said at least one air lift includes an integral curved downstream partition and deflector.

131. Apparatus according to claim 106 and also comprising installing a denitrification unit in at least one of said plurality of treatment stage regions.

132. Apparatus according to claim 131 and wherein said denitrification unit comprises a plurality of axial pumps which provide lift generally without an air flow, thereby to provide an anoxic de-nitrification process.

133. Apparatus according to claim 106 and wherein said at least one air lift comprises an array of air lifts and wherein said array of air lifts comprises a multiplicity of cylindrical air lifts arranged in said plurality of treatment stage regions and separated by said vertical partitions which extend from a bottom location which is spaced from a bottom of said basin by a first vertical separation.

134. Apparatus according to claim 133 and wherein said cylindrical air lifts each comprise:

a hollow shaft which extends from a bottom location spaced from a bottom of said basin by a second vertical separation which exceeds said first separation;

a deflector which is disposed in spaced relationship over each hollow shaft and is disposed at said water level; and

at least one air diffuser which is disposed underlying each hollow shaft to provide an air lift therethrough, thereby causing water to flow into said hollow shafts and upwardly through said hollow shafts, said deflectors causing said water exiting said tops of said hollow shafts to move sideways and downwardly.

135. Apparatus according to claim 134 and also comprising:

a plurality of air diffusers disposed immediately upstream of each said vertical partition for providing control of particle movement and prevention of particle migration.

136. Apparatus according to claim 106 and wherein said at least one air lift produces fluidization of said particles.

137. Apparatus according to claim 106 and wherein said at least one air lift is operative, when said particles become heavily coated with biomass, to cause said particles sometimes to enter said at least one air lift and to be sloughed of some of said biomass as they are propelled upwards by action of said at least one air lift.

138. Waste water treatment apparatus comprising:

at least one basin;

generally vertical partitions located at spaced locations in said at least one basin in order to divide said at least one basin into a plurality of treatment stage regions;

at least one air lift, located in each of said plurality of treatment stage regions, comprising a series of air lifts arranged in each of multiple process stages, including;

an initial air lift assembly including an upstream partition which extends downwardly from a top location above a water level in said basin to a bottom location spaced from a bottom of said basin; and

at least one intermediate air lift assembly; and

a quantity of floatable porous particles loaded into each of said plurality of treatment stage regions, whereby supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions and operating said at least one air lift in each of said plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with said floatable porous particles,

and wherein said upstream partition is attached to a deflector which extends in a downstream direction from said upstream partition at said water level.

139. Waste water treatment apparatus comprising:

at least one basin;

generally vertical partitions located at spaced locations in said at least one basin in order to divide said at least one basin into a plurality of treatment stage regions;

at least one air lift, located in each of said plurality of treatment stage regions, comprising a series of air lifts, arranged in each of multiple process stages, including;

an initial air lift assembly; and

at least one intermediate air lift assembly including an upstream partition separated from a deflector plate which extends in a downstream direction from said upstream partition at a wafer level in said basin; and

a quantity of floatable porous particles loaded into each of said plurality of treatment stage regions, whereby supplying waste water to at least one of said plurality of treatment stage regions and allowing said waste water, but generally not said particles, to flow from at least one of said plurality of treatment stage regions to at least another of said plurality of treatment stage regions and operating said at least one air lift in each of said plurality of treatment stage regions provides aerobic waste water flow therein in operative engagement with said floatable porous particles.

140. Apparatus according to claim 139 and wherein said at least one intermediate air lift assembly also includes a downstream partition which does not extend up to said water level or as close to a bottom of said basin as does said upstream partition.