Methods for removing substances from aqueous solutions

• US 5,045,214 A
• Filed: 05/31/1989
• Issued: 09/03/1991
• Est. Priority Date: 03/21/1983
• Status: Expired due to Fees

• Current Assignee: Union Oil Company of California (Chevron Corp.)
• Original Assignee: Union Oil Company of California (Chevron Corp.)
• Inventors: Walker, Douglas T.
• Primary Examiner(s): Hruskoci, Peter
• Application Number:
  US07/359,872
• Time in Patent Office: 825 Days
• Field of Search: 75/108, 75/609, 204/DIG. 13, 210/702, 210/708, 210/714, 210/718, 210/721, 210/722, 210/724, 210/726, 210/738, 210/717, 210/750, 210/758, 210/912-914, 210/904, 210/908, 55/53, 55/38
• US Class Current: 210/717
• CPC Class Codes: C02F 1/52 by flocculation or precipitation of suspended impurities C02F1/463 takes precedence
• CPC Class Codes: C02F 1/5236 using inorganic agents
• CPC Class Codes: C02F 1/72 by oxidation C02F1/4672 takes precedence
• CPC Class Codes: C02F 2101/18 Cyanides
• CPC Class Codes: C02F 2101/20 Heavy metals or heavy metal compounds
• CPC Class Codes: C02F 2101/203 Iron or iron compound
• CPC Class Codes: C02F 2101/22 Chromium or chromium compounds, e.g. chromates
• CPC Class Codes: Y10S 210/904 -CN containing
• CPC Class Codes: Y10S 210/908 Organic
• CPC Class Codes: Y10S 210/912 Heavy metal

Abstract

Methods are provided for removing contaminants from an aqueous solution to yield a less contaminated aqueous effluent. In one embodiment of the invention, the method comprises coprecipitating non-volatile contaminants (i.e., heavy metals, light metals, cyanide, phenolics, oil and grease, TSS, BOD, COD, and/or TOC) with a carrier precipitate which is formed in situ within the aqueous solution. In another embodiment of the invention, the method comprises partitioning volatile organic contaminants between a liquid phase and a gas phase. In yet a further embodiment, the above versions of the invention are simultaneously performed in the same reaction vessel.

Claims

1. A method for removing one or more contaminants selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof from an aqueous solution comprising the contaminants and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants; and

(b) separating the amorphous precipitate from the solution so as to form an effluent solution having a substantially reduced contaminant concentration, wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a).

2. The method of claim 1 wherein step (a) includes the step of controlling the pH of the solution with a base selected from the group consisting of ammonia, hydroxide containing bases, and mixtures thereof.

3. The method of claim 1 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes.

4. The method of claim 1 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes.

5. The method of claim 1 wherein step (a) includes the step of introducing air into the solution at a rate of about 2 to about 8 l air per about 1000 ppm ferrous ion present in the solution prior to step (a).

6. The method of claim 1 wherein step (a) includes the step of mixing the aqueous solution.

7. The method of claim 1 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9.

8. The method of claim 1 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 7.5 to about 8.

9. The method of claim 1 wherein the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

10. The method of claim 1 wherein the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

11. The method of claim 1 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 2 to about 8 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9; and

the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

12. The method of claim 1 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 4 to about 10 1 air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of

13. The method of claim 1 further comprising the steps of:

(c) introducing additional ferrous ions in the effluent solution to form a modified effluent solution;

(d) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution; and

(e) separating the second precipitate from the modified effluent solution so as to form a second effluent solution having a contaminant concentration less than the contaminant concentration of the effluent solution.

14. The method of claim 13 wherein step (d) includes the step of controlling the pH of the modified effluent solution.

15. The method of claim 13 wherein substantially all of the ferrous ions in the modified effluent solution are oxidized to ferric ions within a period of less than about 30 minutes.

16. The method of claim 13 wherein step (d) includes the step of introducing air into the modified effluent solution at a rate of at least about 1 l air per 1000 ppm ferrous ion present in the modified effluent solution prior to step (d).

17. The method of claim 13 wherein step (d) includes the step of introducing air into the modified effluent solution at a rate of at least about 10 l air 1000 ppm ferrous ion present in the modified effluent solution prior to step (d).

18. The method of claim 13 wherein step (d) includes the step of mixing the aqueous solution.

19. The method of claim 13 wherein step (d) includes the step of controlling the pH of the modified effluent solution so that the pH of the modified effluent solution is about 6 to about 9.5.

20. The method of claim 1 wherein the method is a continuous process.

21. The method of claim 1 wherein the method is a batch process.

22. The method of claim 1 wherein the amorphous precipitate contains essentially all of the ferric ions formed in step (a).

23. The method of claim 1 wherein the amorphous precipitate consists essentially of an amorphous material.

24. The method of claim 1 wherein the contaminant is beryllium ions.

25. A method of removing contaminants selected from the group consisting of aluminum ions, beryllium ions, cyanide ions, and mixtures thereof from an aqueous solution comprising the contaminants and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants; and

(b) separating the amorphous precipitate from the solution so as to form an effluent solution having a substantially reduced contaminant concentration, wherein a portion of the contaminant concentration, wherein a portion of the contaminants are cyanide ions and a portion of the contaminants are selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof;

the molar ratio of the ferrous ions to the contaminants in the aqueous solution is about 1;

1 to about 10;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5;

the substantially completely amorphous precipitate comprises a substantial portion of the cyanide ions;

the effluent solution has a substantially reduced concentration of the cyanide ions; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a).

26. The method of claim 25 wherein the molar ratio of the ferrous ions to the contaminants in the aqueous solution is at least about 4:

1.

27. The method of claim 25 wherein the molar ratio of the ferrous ions to the contaminants in the aqueous solution is at least about 8:

1.

28. The method of claim 25 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 1:

1.

29. The method of claim 25 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 4:

1.

30. The method of claim 25 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 8:

1.

31. The method of claim 25 wherein the molar ratio of the ferrous ions to the contaminants in the aqueous solution is about 2:

1 to about 8;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 2 to about 8 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9; and

the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

32. The method of claim 25 wherein the molar ratio of the ferrous ions to the contaminants in the aqueous solution is about 4:

1 to about 8;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 4 to about 10 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 7.5 to about 8; and

the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

33. The method of claim 25 wherein a portion of the contaminants are beryllium ions.

34. The method of claim 25 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes.

35. The method of claim 25 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes.

36. The method of claim 25 wherein step (a) includes the step of introducing air into the solution at a rate of about 2 to about 8 l per about 1000 ppm ferrous ion present in the solution prior to step (a).

37. The method of claim 25 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9.

38. The method of claim 25 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 7.5 to about 8.

39. The method of claim 25 wherein the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

40. The method of claim 25 wherein the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

41. The method of claim 25 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 1:

1.

42. The method of claim 25 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 4:

1.

43. The method of claim 25 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 8:

1.

44. A method for removing contaminants selected the group consisting of aluminum ions, beryllium ions, heavy metal ions, and mixtures thereof from an aqueous solution comprising the contaminants and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants; and

(b) separating the amorphous precipitate from the solution so as to form an effluent solution having a substantially reduced contaminant concentration, wherein a portion of the contaminants are at least one heavy metal ion and a portion of the contaminants are selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof;

the weight ratio of the ferrous ions to the contaminants in the aqueous solution is at least about 1;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5;

the substantially completely amorphous precipitate comprises a substantial portion of the heavy metal ions;

the effluent solution has a substantially reduced concentration of the heavy metal ions; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a).

45. The method of claim 44 wherein the weight ratio of the ferrous ions to the contaminants in the aqueous solution is less than about 10:

1.

46. The method of claim 44 wherein the weight ratio of the ferrous ions to the contaminants in the aqueous solution is about 1:

1 to about 10;

1.

47. The method of claim 44 wherein the weight ratio of the ferrous ions to the contaminants in the aqueous solution is about 4:

1 to about 6;

1.

48. The method of claim 44 wherein the weight ratio of the ferrous ions to the contaminants in the aqueous solution is about 1:

1 to about 10;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 2 to about 8 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9; and

the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

49. The method of claim 44 wherein the weight ratio of the ferrous ions to the contaminants in the aqueous solution is about 4:

1 to about 6;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 4 to about 10 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 7.5 to about 8; and

the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

50. The method of claim 44 wherein the contaminants further comprise step (a) includes the step of occluding a substantial portion of the heavy metal contaminant in the amorphous precipitate.

51. The method of claim 44 wherein a portion of the contaminants are beryllium ions.

52. The method of claim 44 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes.

53. The method of claim 44 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes.

54. The method of claim 44 wherein step (a) includes the step of introducing air into the solution at a rate of about 2 to about 8 l per about 1000 ppm ferrous ion present in the solution prior to step (a).

55. The method of claim 44 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9.

56. The method of claim 44 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 7.5 to about 8.

57. The method of claim 44 wherein the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

58. The method of claim 44 wherein the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

59. The method of claim 44 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 1:

1.

60. The method of claim 44 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 4:

1.

61. The method of claim 44 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 8:

1.

62. A method for removing contaminants selected from the group consisting of aluminum ions, beryllium ions, cyanide ions, heavy metal ions, and mixtures thereof from an aqueous solution comprising the contaminants and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants; and

(b) separating the amorphous precipitate from the solution so as to form an effluent solution having a substantially reduced contaminant concentration, wherein a portion of the contaminants are cyanide ions and at least one heavy metal ion and a portion of the contaminants are selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof;

the substantially completely amorphous precipitate comprises a substantial portion of the cyanide ions and the heavy metal ions;

the effluent solution has a substantially reduced concentration of the cyanide ions and the heavy metal ions;

the concentration of the ferrous ions in the aqueous solution is equal to about one to about ten times the molar concentration of the contaminants;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a).

63. The method of claim 62 wherein the concentration of the ferrous ions in the aqueous solution is equal to about two to about eight times the molar concentration of the contaminants.

64. The method of claim 62 wherein the concentration of the ferrous ions in the aqueous solution is equal to about four to about six times the molar concentration of the contaminants.

65. The method of claim 62 wherein the concentration of the ferrous ions in the aqueous solution is equal to about two to about eight times the molar concentration of the contaminants;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 2 to about 8 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9; and

the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

66. The method of claim 62 wherein the concentration of the ferrous ions in the aqueous solution is equal to about four to about six times the molar concentration of the contaminants;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes;

step (a) includes the steps of introducing air into the solution at a rate of about 4 to about 10 l air per about 1000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 7.5 to about 8; and

the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

67. The method of claim 62 wherein a portion of the contaminants are beryllium ions.

68. The method of claim 62 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 15 minutes.

69. The method of claim 62 wherein substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 10 minutes.

70. The method of claim 62 wherein step (a) includes the step of introducing air into the solution at a rate of about 2 to about 8 l per about 1000 pm ferrous ion present in the solution prior to step (a).

71. The method of claim 62 wherein step (a) includes the step of controlling the pH of the solution so that the pH of the solution is about 6.5 to about 9.

72. The method of claim 62 wherein step (a) includes the step of controlling the pH of the solution so That the pH of the solution is about 7.5 to about 8.

73. The method of claim 62 wherein the total concentration of the contaminants in the effluent solution is less than about 5% of the concentration of the contaminants in the aqueous solution prior to step (a).

74. The method of claim 62 wherein the total concentration of the contaminants in the effluent solution is less than about 1% of the concentration of the contaminants in the aqueous solution prior to step (a).

75. The method of claim 62 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 1:

1.

76. The method of claim 62 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 4:

1.

77. The method of claim 62 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 8:

1.

78. A method for removing volatile organics and one or more contaminants selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof from an aqueous solution comprising the volatile organics, the contaminants, and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants;

(b) removing a substantial portion of the volatile organics by introducing a gas into the solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(c) separating the precipitate from the solution so as to form an effluent solution having a reduced contaminant and volatile organic concentration, wherein steps (a) and (b) are performed simultaneously and include the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a), and the concentration of the volatile organics in the effluent is less than about 20% of the concentration of the volatile organics in the aqueous solution prior to step (b).

79. The method of claim 78 wherein steps (a) and (b) include the step of mixing the aqueous solution.

80. The method of claim 78 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution; and

(f) separating the second precipitate from the modified effluent solution so as to form a second effluent solution having a contaminant concentration less than the contaminant concentration of the effluent solution.

81. The method of claim 78 further comprising the steps of introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20 so that any volatile organic content to the effluent is further reduced.

82. The method of claim 78 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution;

(f) introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(g) separating the precipitate from the modified effluent solution so as to form a second effluent solution having a contaminant and volatile organic concentration less than the contaminant volatile organic concentration of the effluent solution.

83. The method of claim 78 wherein the contaminant is beryllium ions.

84. A method for removing volatile organics and contaminants selected from the group consisting of aluminum ions, beryllium ions, cyanide ions, and mixtures thereof from an aqueous solution comprising the volatile organics, the contaminants, and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants;

(b) removing a substantial portion of the volatile organics by introducing a gas into the solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(c) separating the precipitate from the solution so as to form an effluent solution having a reduced contaminant and volatile organic concentration, wherein a portion of the contaminants are cyanide ions and a portion of the contaminants are selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof;

the molar ratio of the ferrous ions to the contaminants in the aqueous solution is about 1;

1 to about 10;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

steps (a) and (b) are performed simultaneously and include the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5;

the substantially completely amorphous precipitate comprises a substantial portion of the cyanide ions;

the effluent solution has a substantially reduced concentration of the cyanide ions; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a), and the concentration of the volatile organics in the effluent is less than about 20% of the concentration of the volatile organics in the aqueous solution prior to step (b).

85. The method of claim 84 further comprising the step of adding ferrous ions to the aqueous solution to increase the ferrous ion-contaminant molar ratio to at least about 1:

1.

86. The method of claim 84 wherein a portion of the contaminants are beryllium ions.

87. The method of claim 84 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution; and

(f) separating the second precipitate from the modified effluent solution so as to form a second effluent solution having a contaminant concentration less than the contaminant concentration of the effluent solution.

88. The method of claim 84 further comprising the steps of introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20 so that any volatile organic content to the effluent is further reduced.

89. The method of claim 84 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution;

(f) introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(g) separating the precipitates from the modified effluent solution so as to form a second effluent solution having a contaminant and volatile organic concentration less than the contaminant and volatile organic concentration of the effluent solution.

90. A method for removing volatile organics and contaminants selected from the group consisting of aluminum ions, beryllium ions, heavy metal ions, and mixtures thereof from an aqueous solution comprising the volatile organics, the contaminants, and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants;

(b) removing a substantial portion of the volatile organics by introducing a gas into the solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(c) separating the precipitate from the solution so as to form an effluent solution having a reduced contaminant and volatile organic concentration, wherein a portion of the contaminants are at least one heavy metal ion and a portion of the contaminants are selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof;

the molar ratio of the ferrous ions to the contaminants in the aqueous solution is at least about 1;

1;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

steps (a) and (b) are performed simultaneously and include the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5;

the substantially completely amorphous precipitate comprises a substantial portion of the heavy metal ions;

the effluent solution has a substantially reduced concentration of the heavy metal ions; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a), and the concentration of the volatile organics in the effluent is less than about 20% of the concentration of the volatile organics in the aqueous solution prior to step (b).

91. The method of claim 90 wherein a portion of the contaminants are beryllium ions.

92. The method of claim 90 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution; and

(f) separating the second precipitate from the modified effluent solution so as to form a second effluent solution having a contaminant concentration less than the contaminant concentration of the effluent solution.

93. The method of claim 90 further comprising the steps of introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20 so that any volatile organic content to the effluent is further reduced.

94. The method of claim 90 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution;

(f) introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(g) separating the precipitates from the modified effluent solution so as to form a second effluent solution having a contaminant and volatile organic concentration less than the contaminant and volatile organic concentration of the effluent solution.

95. A method for removing volatile organics and contaminants selected from the group consisting of aluminum ions, beryllium ions, cyanide ions, heavy metal ions, and mixtures thereof from an aqueous solution comprising the volatile organics, the contaminants, and ferrous ions, the method comprising the steps of:

(a) rapidly oxidizing substantially all the ferrous ions in the solution to ferric ions so as to rapidly form a substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of the contaminants;

(b) removing a substantial portion of the volatile organics by introducing a gas into the solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20; and

(c) separating the precipitate from the solution so as to form an effluent solution having a reduced contaminant and volatile organic concentration, wherein a portion of the contaminants are cyanide ions and at least one heavy metal ion and a portion of the contaminants are selected from the group consisting of aluminum ions, beryllium ions, and mixtures thereof;

the substantially completely amorphous precipitate comprises a substantial portion of the cyanide ions and the heavy metal ions;

the effluent solution has a substantially reduced concentration of the cyanide ions and the heavy metal ions;

the concentration of the ferrous ions in the aqueous solution is equal to about one to abut ten times the molar concentration of the contaminants;

substantially all of the ferrous ions in the solution are oxidized to ferric ions within a period of less than about 30 minutes;

steps (a) and (b) are performed simultaneously and include the steps of introducing air into the solution at a rate of about 1 to about 10 l air per about 1,000 ppm ferrous ion present in the solution prior to step (a), and controlling the pH of the solution so that the pH of the solution is about 6 to about 9.5; and

the total concentration of the contaminants in the effluent solution is less than about 10% of the concentration of the contaminants in the aqueous solution prior to step (a), and the concentration of the volatile organics in the effluent is less than about 20% of the concentration of the volatile organics in the aqueous solution prior to step (b).

96. The method of claim 95 wherein a portion of the contaminants are beryllium ions.

97. The method of claim 95 further comprising the steps of:

(d) introducing additional ferrous ions into the effluent solution to form a modified effluent solution;

(e) rapidly oxidizing substantially all the ferrous ions in the modified effluent solution to ferric ions so as to rapidly form a second substantially completely amorphous precipitate comprising a substantial portion of ferric hydroxide and a substantial portion of any contaminant present in the effluent solution; and

(f) separating the second precipitate from the modified effluent solution so as to form a second effluent solution having a contaminant concentration less than the contaminant concentration of the effluent solution.

98. The method of claim 95 further comprising the steps of introducing additional gas into the effluent solution at a rate sufficient to achieve an average volumetric flux ratio of gas to water of at least about 20 so that any volatile organic content to the effluent is further reduced.