Claims:1. A system (100) for treatment of a cyanide containing effluent, the system comprising:
a sectionalized tray column (110), said column comprising:
an effluent inlet (111) defined near a first end of the column;
a gas inlet (112) defined near a second end of the column;
a gas outlet (114) defined near the first end of the column;
a treated effluent outlet (113) defined near the second end of the column;
a plurality of liquid distribution trays (115), each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes (116) allowing passage of a gas therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon; and
a plurality of down-comers (117) configured along an inner surface of the column, each of said plurality of down-comers defining an upper section (117-1) and a lower section (117-2), said upper section (117-1) configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays (115a) and said lower section (117-2) configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) downstream from said one of the plurality of liquid distribution trays;
a unit (120) for controlling introduction of said cyanide containing effluent to the sectionalized tray column; and
a unit (130) for controlling introduction of the gas to the sectionalized tray column.
2. The system as claimed in claim 1, wherein said gas is an ozone containing gas.
3. The system as claimed in claim 1, wherein said gas is caused to flow through said sectionalized tray column (110) in a direction substantially opposite to the direction of flow of said cyanide containing effluent.
4. The system as claimed in claim 1, wherein the system (100) comprises an ozone generating unit (140).
5. The system as claimed in claim 1, wherein said plurality of holes (116) are of size ranging from 1 mm to 4 mm.
6. The system as claimed in claim 1, wherein said cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm and has a pH ranging from 9 to 12.
7. The system as claimed in claim 1 wherein said cyanide content in treated effluent is reduced to less than about 0.2 ppm.
8. A sectionalized tray column (110) for treatment of a cyanide containing effluent, said column comprising:
an effluent inlet (111) defined near a first end of the column;
a gas inlet (112) defined near a second end of the column;
a gas outlet (114) defined near the first end of the column;
a treated effluent outlet (113) defined near the second end of the column;
a plurality of liquid distribution trays (115), each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes (116) allowing passage of a gas therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon; and
a plurality of down-comers (117) configured along an inner surface of the column, each of said plurality of down-comers defining an upper section (117-1) and a lower section (117-2), said upper section (117-1) configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays (115a) and said lower section (117-2) configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) downstream from said one of the plurality of liquid distribution trays.
9. A process for treatment of a cyanide containing effluent, comprising the steps of:
a) controlling pH of the cyanide containing effluent in a range of 9 to 12;
b) introducing the cyanide containing effluent to a sectionalized tray column (110), said column comprising:
an effluent inlet (111) defined near a first end of the column;
a gas inlet (112) defined near a second end of the column;
a gas outlet (113) defined near the first end of the column;
a treated effluent outlet (114) defined near the second end of the column;
a plurality of liquid distribution trays (115), each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes (116); and
a plurality of down-comers (117) configured along an inner surface of the column, each of said down-comers defining an upper section (117-1) and a lower section (117-2), said upper section (117-1) configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays (115a) and said lower section (117-2) configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) downstream from said one of the plurality of liquid distribution trays; and
c) introducing an ozone containing gas to the column (110) such that the ozone containing gas passes through the plurality of holes (116) defined on each of the liquid distribution trays (115) and comes in contact with the volume of the cyanide containing effluent held thereon to produce a treated effluent.
10. The process as claimed in claim 9, wherein the step of controlling pH of the cyanide containing effluent comprises treating the cyanide containing effluent with a caustic lye.
11. The process as claimed in claim 9, wherein the process comprises: controlling any or a combination of: rate of feeding the cyanide containing effluent to the sectionalized tray column, and rate of introduction of the ozone containing gas to the column such that the cyanide containing effluent passes through the down-comer substantially precluding passage thereof through said plurality of holes defined on the liquid distribution trays.
12. The process as claimed in claim 9, wherein the process is a continuous process.
13. The process as claimed in claim 9, wherein the treated effluent has a cyanide content ranging from 0.01 ppm to 0.2 ppm.
14. The process as claimed in claim 9, wherein the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm, and wherein the ozone containing gas has an ozone concentration ranging from 5% to 20%.
15. The process as claimed in claim 9, wherein the cyanide content in the treated effluent is less than 0.5 ppm.
, Description:TECHNICAL FIELD
[0001] The present disclosure pertains to the technical field of effluent treatment. In particular, the present disclosure relates to a system and method for treatment of cyanide containing effluent that is efficacious, simple to operate and cost effective.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Due to usage of cyanide derivatives in large number of chemical manufacturing operations such as gold/silver mining, dyeing, paper pulping, photograph processing, steel industry, agriculture industry, metal plating processes, presence of cyanide content in effluents released through such chemical industries is increasing, thereby posing serious pollution problems. Discharge of such effluents including cyanide content into water/water sources without proper treatment can cause contamination thereof, which is harmful to the society and overall ecosystem.
[0004] Considerable research has been done so far to achieve complete/maximum destruction of cyanide content in such effluents. For example, it has been proposed that the undesirable cyanides can be precipitated as insoluble heavy metal compounds by addition of heavy metal salt(s) to the cyanide containing effluents. This method, however, is somewhat disadvantageous in that - bulky equipment is required and the cyanides cannot be completely eliminated. Chemical methods has also been proposed and has been employed, albeit with little commercial success, for elimination or destruction of undesirable cyanides, which involves, for example, addition of peroxides and/or combination of peroxides with other chemicals; addition of active chlorine etc. for the purpose of causing oxidation of the cyanides. All such methods have their own sets of disadvantages such as these processes are very slow, generation of additional hazardous chemicals during effluent treatment and the likes. Further, such conventional chemical processes could not achieve the desired effect of complete/maximum destruction/elimination of cyanide(s) in the effluents so as to meet pollution standards (such as those prescribed by the Pollution Control Board).
[0005] Utilization of ozone has also been proposed in few studies to treat the cyanide containing effluents. For example, Nava et al. in “Use of ozone in the treatment of cyanide containing effluents”; The European Journal of Mineral Processing and Environmental Protection; Vol.3, No.3, 1303-0868, 2003, pp. 316-323 has summarized the research work, done at CINVESTAV between 1996 and 2001, studying the use of ozone to treat cyanide containing effluents, discussing the effects of pH, temperature and ozone addition rate on the cyanide oxidation rate, contents whereof are incorporated herein by way of reference. As noted by Nava et al. possibility of cyanide oxidation by ozone in synthetic solutions was first studied in 1959, and despite such possibility being known for such a long time (over 60 years), the technique of utilization of ozone for treatment of cyanide containing effluents has found little commercial application and/or commercial success, plausibly owing to requirement of extensive instrumentation and control thereof, lack of effectiveness/efficacy in terms of cyanide oxidation by ozone at a commercial scale, cost implications and such other shortcomings associated therewith.
[0006] Alike the study of Nava et al. discussed above, several other studies have been done so far towards treatment of cyanide containing solutions by ozone, for example, Teramoto et al. in “Overall rate of ozone oxidation of cyanide in bubble column”; Journal of Chemical Engineering of Japan, Vol. 14, No. 2, 1981, pp 111-115 proposed oxidation of cyanide with Ozone using a bubble column; F. Barriga-Ordonez et al. in “Cyanide oxidation by ozone in a steady-state flow bubble column”, Minerals Engineering, 19 (2006), 117–122 proposed oxidation of cyanide in synthetic alkaline solutions by ozone in a counter current bubble column; and F. R. Carrillo-Pedroza et al.in “Cyanide Oxidation by Ozone in Cyanidation Tailings: Reaction Kinetics” Minerals Engineering, Vol. 13, No. 5, pp. 541-548, 2000 proposed oxidation of cyanide by ozone in aqueous solutions using a bubble column reactor which was operated at different conditions of pH, ozone dosage rate, gas flow rate and cyanide concentration, contents of each of these documents are incorporated herein by way of reference. It could be noted that the bubble columns referred to and used in several studies make use of packed bubble columns (batch processes), wherein efficient cyanide effluent treatment could not be achieved; further, installation of such bubble columns and/or packed columns and operation thereof is not cost effective.
[0007] Accordingly, there remained a long felt need in the art of a system and method for treatment of cyanide containing effluent that is efficacious, simple to operate and cost effective.The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
[0008] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

OBJECTS OF THE INVENTION
[0009] It is an object of the present disclosure to provide a system for treatment of a cyanide containing effluent that is efficacious, simple to operate and cost effective.
[0010] Another object of the present disclosure is to provide a method for treatment of a cyanide containing effluent that is efficacious, simple to operate and cost effective.
[0011] Another object of the present disclosure is to provide a system and method for treatment of a cyanide containing effluent that can be implemented at an industrial scale.
[0012] Further object of the present disclosure is to provide a method for treatment of a cyanide containing effluent that affords treated effluents meeting the discharge standards as prescribed by the Pollution Control Boards.
[0013] Further object of the present disclosure is to provide a method for treatment of a cyanide containing effluent that does not make use of hazardous chemicals.
[0014] Still further object of the present disclosure is to provide a method for treatment of a cyanide containing effluent that is less time consuming.
[0015] Still further object of the present disclosure is to provide a method for treatment of a cyanide containing effluent that precludes generation of additional sludge after oxidation of cyanide content of the effluent.

SUMMARY
[0016] The present disclosure pertains to the technical field of effluent treatment. In particular, the present disclosure relates to a system and method for treatment of cyanide containing effluent that is efficacious, simple to operate and cost effective.
[0017] An aspect of the present disclosure provides a system for treatment of a cyanide containing effluent, the system comprising: a sectionalized tray column, said column comprising: an effluent inlet defined near a first end of the column; a gas inletdefined near a second end of the column; a gas outletdefined near the first end of the column; a treated effluent outletdefined near the second end of the column; a plurality of liquid distribution trays, each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes allowing passage of a gas therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon; and a plurality of down-comers configured along an inner surface of the column, each of said plurality of down-comers defining an upper section and a lower section, said upper section configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays and said lower section configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray downstream from said one of the plurality of liquid distribution trays; a unit for controlling introduction of said cyanide containing effluent to the sectionalized tray column; and a unit for controlling introduction of the gas to the sectionalized tray column. In an embodiment, the gas is an ozone containing gas. In an embodiment, the gas is caused to flow through said sectionalized tray column in a direction substantially opposite to the direction of flow of said cyanide containing effluent. In an embodiment, the system (100) comprises an ozone generating unit. In an embodiment, the plurality of holes are of size ranging from 1 mm to 4 mm. In an embodiment, the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm. In an embodiment, the cyanide containing effluent has a pH ranging from 9 to 13.
[0018] Another aspect of the present disclosure provides a modified column for treatment of a cyanide containing effluent, said column comprising: an effluent inlet defined near a first end of the column; a gas inletdefined near a second end of the column; a gas outletdefined near the first end of the column; a treated effluent outletdefined near the second end of the column; a plurality of liquid distribution trays, each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes allowing passage of a gas therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon; and a plurality of down-comers configured along an inner surface of the column, each of said plurality of down-comers defining an upper section and a lower section, said upper section configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays and said lower section configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray downstream from said one of the plurality of liquid distribution trays. In an embodiment, the gas is an ozone containing gas. In an embodiment, the gas is caused to flow through the modified column in a direction substantially opposite to the direction of flow of said cyanide containing effluent. In an embodiment, the plurality of holes are of size ranging from 1 mm to 4 mm. In an embodiment, the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm. In an embodiment, the cyanide containing effluent has a pH ranging from 9 to 13.
[0019] Further aspect of the present disclosure relates to a process for treatment of a cyanide containing effluent, the process comprising the steps of: controlling pH of the cyanide containing effluent to be within the range of 9 to 13; introducing the cyanide containing effluent to a sectionalized tray column, said modified column comprising: an effluent inlet defined near a first end of the column; a gas inletdefined near a second end of the column; a gas outletdefined near the first end of the column; a treated effluent outletdefined near the second end of the column; a plurality of liquid distribution trays, each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes; and a plurality of down-comers configured along an inner surface of the column, each of said down-comers defining an upper section and a lower section, said upper section configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays and said lower section configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray downstream from said one of the plurality of liquid distribution trays; and introducing an ozone containing gas to the sectionalized tray column such that the ozone containing gas passes through the plurality of holes defined on each of the liquid distribution trays and comes in contact with the volume of the cyanide containing effluent held thereon to produce a treated effluent.
[0020] In an embodiment, the step of controlling pH of the cyanide containing effluent comprises mixing the cyanide containing effluent with a caustic lye to control the pH of the cyanide containing effluent to be within the range of 9 to 13. In an embodiment, the process comprises: controlling any or a combination of: rate of introduction of the cyanide containing effluent to the modified column, and rate of introduction of the ozone containing gas to the sectionalized tray column such that the cyanide containing effluent passes through the down-comer substantially precluding passage thereof through said plurality of holes defined on the liquid distribution trays. In an embodiment, the process is a continuous process. In an embodiment, the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm, and wherein the ozone containing gas has an ozone concentration ranging from 5% to 20%. In an embodiment, the treated effluent has a cyanide content ranging from 0.01 ppm to 0.2 ppm.
[0021] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0023] FIG. 1 illustrates an exemplary schematic showing a system for treatment of a cyanide containing effluent, in accordance with an embodiment of the present disclosure.
[0024] FIG. 2 illustrates an exemplary sectional view of the sectionalized tray column, realized in accordance with an embodiment of the present disclosure.
[0025] FIG. 3 illustrates an exemplary flow chart illustrating a process for treatment of a cyanide containing effluent, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0026] The following is a detailed description of embodiments of the present invention. The embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
[0027] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0028] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability.
[0029] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0030] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0031] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0032] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0033] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Not with standing that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0034] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0035] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0036] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0037] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0038] The present disclosure pertains to the technical field of effluent treatment. In particular, the present disclosure relates to a system and method for treatment of cyanide containing effluent that is efficacious, simple to operate and cost effective.
[0039] An aspect of the present disclosure provides a system for treatment of a cyanide containing effluent, the system comprising: a sectionalized tray column, said column comprising: an effluent inlet defined near a first end of the column; a gas inletdefined near a second end of the column; a gas outletdefined near the first end of the column; a treated effluent outletdefined near the second end of the column; a plurality of liquid distribution trays, each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes allowing passage of a gas therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon; and a plurality of down-comers configured along an inner surface of the column, each of said plurality of down-comers defining an upper section and a lower section, said upper section configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays and said lower section configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray downstream from said one of the plurality of liquid distribution trays; a unit for controlling introduction of said cyanide containing effluent to the sectionalized tray column; and a unit for controlling introduction of the gas to the sectionalized tray column.
[0040] In an embodiment, the gas is an ozone containing gas. For example, a gas having ozone concentration ranging from 5% to 80%, preferably, having ozone concentration ranging from 5% to 40%, more preferably, having ozone concentration ranging from 5% to 20%, preferably 5% to 15%, and most preferably having ozone concentration ranging from 10% to 15%.. The ozone containing gas can be generated using the conventional ozonators or ozone generating devices/systems well known to persons skilled in the art. In an embodiment, the system comprises an ozone generating unit.
[0041] In an embodiment, the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm. However, the system can also be used for treatment of cyanide containing effluents having cyanide content less than about 2 ppm or more than about 30 ppm, by adapting the system suitably, for example, for treatment of cyanide containing effluents having cyanide content of more than about 30 ppm, residence time of the cyanide containing effluents in the sectionalized tray column may be increased and/or the dosage of ozone may be increased.
[0042] In an embodiment, the cyanide containing effluent has a pH ranging from 9 to 13. pH of the cyanide containing effluent can be adjusted by use of suitable acidic or alkaline substances as known to persons skilled in the art. For example, cyanide containing effluent can be mixed with desired amount of caustic lye to adjust the pH thereof to be within the range of 9 to 13. Preferably, the cyanide containing effluent has a pH ranging from 10 to 12.
[0043] In an embodiment, the gas is caused to flow through said sectionalized tray column in a direction substantially opposite to the direction of flow of said cyanide containing effluent. For example, the gas may be introduced near bottom of the column and the cyanide containing effluent may be introduced near top of the column, such that flow of the gas is counter-current to the flow of the cyanide containing effluent.
[0044] FIG. 1 illustrates an exemplary schematic showing a system (100) for treatment of a cyanide containing effluent, in accordance with an embodiment of the present disclosure. As can be seen from FIG. 1, the system (100) includes: a sectionalized tray column (110); a unit (120) for controlling introduction of said cyanide containing effluent to the column; and a unit (130) for controlling introduction of gas (such as ozone containing has) to the column. FIG. 2 illustrates an exemplary sectional view of the modified column, realized in accordance with an embodiment of the present disclosure.
[0045] As can be seen from FIG. 1 and FIG. 2, the sectionalized tray column includes: an effluent inlet (111) defined near a first end of the column, for example, near top of the column; a gas inlet(112) defined near a second end of the column, for example, near bottom of the column; a gas outlet(114) defined near the first end of the column, for example, near top of the column; a treated effluent outlet(113) defined near the second end of the column, for example, near bottom of the column; a plurality of liquid distribution trays (115a, 115b... collectively shown as 115); and a plurality of down-comers (117a, 117b,117c...collectively shown as 117) configured along an inner surface of the column. Each of the liquid distribution trays (115) are configured to hold a volume of the cyanide containing effluent, and each of the liquid distribution trays defines a plurality of holes (collectively shown as 116) allowing passage of a gas (such as ozone containing gas) therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon. In an embodiment, the plurality of holes are of size ranging from 1 mm to 4 mm, preferably, of size ranging from 1 mm to 3 mm. As can also be seen from FIG. 2, each of the down-comers (117) defines an upper section (117-1) and a lower section (117-2);the upper section (117-1) is configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays (115a) and the lower section (117-2) is configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) downstream from said one of the plurality of liquid distribution trays (115a), preferably, with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) immediately downstream from said one of the plurality of liquid distribution trays (115a).
[0046] The unit (120) for controlling introduction of said cyanide containing effluent to the sectionalized tray column may include: one or more flow and/or pressure regulating devices such as commercially available flow control valves (e.g. ball valve) that may be used for controlling flow and/or pressure of the fluid; one or more flow and/or pressure measurement devices such as rotameter; one or more pumping devices such as peristaltic pump and such other devices as known to persons skilled in the art. In an embodiment, the unit (120) for controlling introduction of said cyanide containing effluent to the column includes a peristaltic pump (121) and a rotameter (122).
[0047] The unit (130) for controlling introduction of gas (such as ozone containing has) to the sectionalized tray column may include: one or more flow and/or pressure regulating devices such as commercially available flow control valves (e.g. ball valve) that may be used for controlling flow and/or pressure of the gas; one or more flow and/or pressure measurement devices such as rotameter and such other devices as known to persons skilled in the art. In an embodiment, the unit (130) for controlling introduction of gas (such as ozone containing has) to the sectionalized tray column includes: a rotameter (131) and a flow regulating valve (132).
[0048] The system can also include an ozone generating unit (140), such as ozonators as known to persons skilled in the art. One or more oxygen gas cylinders may be connected to the ozonato(s) affording production of ozone containing gas. It should be appreciated that instead of the ozone generating unit (140), the system can have one or more sources of the ozone containing gas (for example, cylinders filled with ozone containing gas) that may be connected to the unit (130) for controlling introduction of the ozone containing gas to the sectionalized tray column.
[0049] In operation, in accordance with an embodiment, the cyanide containing effluent is introduced in the column through effluent inlet (111), and the ozone containing gas is introduced in the column through gas inlet (112). The unit (120) affords controlling of introduction of the cyanide containing effluent to the column, while the unit (130) affords controlling of introduction of ozone containing gas to the column. As the cyanide containing effluent enters the column, a volume of the cyanide containing effluent is held on the first liquid distribution tray (115a). Holes (116) defined on the first liquid distribution tray (115a) affords passage of the ozone containing gas therethrough such that the ozone present in the gas comes in contact with the volume of the cyanide containing effluent causing oxidation of the cyanide present in the effluent. Rate of introduction of the cyanide containing effluent and/or rate of introduction of the ozone containing gas to the column should be controlled/adjusted such that the cyanide containing effluent does not substantially pass through the plurality of holes (116) defined on the liquid distribution tray (115a). As the cyanide containing effluent rises above the level of upper section (117b-1) of the down-comer (117b), the cyanide containing effluent flows through the down-comer (117b) and a volume of the cyanide containing effluent is held on the liquid distribution tray (115b) downstream from the first liquid distribution tray (115a). Holes (116) defined on the liquid distribution tray (115b) affords passage of the ozone containing gas therethrough while substantially preventing passage of the cyanide containing effluent therethrough, such that the ozone present in the gas comes in contact with the volume of the cyanide containing effluent causing oxidation of the cyanide present in the effluent. As the cyanide containing effluent rises above the level of upper section (117c-1) of the down-comer (117c), the cyanide containing effluent flows through the down-comer (117c) and a volume of the cyanide containing effluent is held on the liquid distribution tray (115c) downstream from the liquid distribution tray (115b). As can also be seen from FIG.2, the upper section of the down-comer (117b-1, 117c-1.. collectively, 117-1) is configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays (115a) and the lower section (117b-2, 117c-2... collectively, 117-2) is configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) downstream from the one of the plurality of liquid distribution trays (115a). Accordingly, the cyanide containing effluent flows through the sectionalized tray column and the cyanide present therein gets oxidized generating a treated effluent having reduced cyanide content. Typically, the residence time of the cyanide containing effluent in the column may be in the range of 5 minutes to 200 minutes, preferably, in the range of 5 minutes to 100 minutes, more preferably, in the range of 5 minutes to 30 minutes and most preferably, in the range of 10 minutes to 20 minutes. The treated effluent, having reduced cyanide content as compared to the cyanide containing effluent introduced in the column, leaves the column from the treated effluent outlet (113) defined near bottom of the column. The unreacted ozone and oxygen gas (generated upon reaction between the ozone and the cyanide content) leaves the column through a gas outlet (114) defined near the top of the column. The unreacted ozone and oxygen gas leaving the column may be sent to one or more scrubbing zones or one or more ozone destruction zones, as known in the art, before being released in the environment.
[0050] It is noteworthy that the conventional bubble columns define a long continuous section, typically, across whole of the volume/length of the column, and several publications suggested utilization thereof for effecting treatment of cyanide containing effluent (e.g. some of the documents referenced in the background section hereinabove), wherein ozone or ozone containing gas is bubbled from/near the bottom such that the rising ozone or ozone containing gas reacts with the cyanide containing effluent held in the column resulting in oxidation of the cyanide. Utilization of the modified sectionalized tray column of the present disclosure affords several fold increase in surface area of the cyanide containing effluent coming in contact with the ozone containing gas (as compared to the conventional bubble columns), as a volume of cyanide containing effluent is held over each of the liquid distribution trays and the ozone containing gas passes through the holes defined on each of the liquid distribution trays coming in contact therewith, as would be apparent to persons skilled in the art. Utilization of the sectionalized tray column of the present disclosure also affords better control over the uniformity of treatment of the cyanide containing effluent and less wastage of ozone or ozone containing gas (i.e. the amount of unreacted ozone leaving the column through its outlet is less), while allowing for continuous operation/process of treatment of the cyanide containing effluent.
[0051] Accordingly, another aspect of the present disclosure provides a sectionalized tray column for treatment of a cyanide containing effluent, said column comprising: an effluent inlet defined near a first end of the column; a gas inlet defined near a second end of the column; a gas outlet defined near the first end of the column; a treated effluent outlet defined near the second end of the column; a plurality of liquid distribution trays, each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes allowing passage of a gas therethrough such that the gas comes in contact with the volume of the cyanide containing effluent held thereon; and a plurality of down-comers configured along an inner surface of the column, each of said plurality of down-comers defining an upper section and a lower section, said upper section configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays and said lower section configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray downstream from said one of the plurality of liquid distribution trays. In an embodiment, the gas is an ozone containing gas. In an embodiment, the gas is caused to flow through the sectionalized tray column in a direction substantially opposite to the direction of flow of said cyanide containing effluent. In an embodiment, the plurality of holes are of size ranging from 1 mm to 4 mm. In an embodiment, the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm. In an embodiment, the cyanide containing effluent has a pH ranging from 9 to 13.
[0052] Further aspect of the present disclosure relates to a process for treatment of a cyanide containing effluent, the process comprising the steps of: controlling pH of the cyanide containing effluent to be within the range of 9 to 13; introducing the cyanide containing effluent to a sectionalized tray column, said modified column comprising: an effluent inlet defined near a first end of the column; a gas inletdefined near a second end of the column; a gas outletdefined near the first end of the column; a treated effluent outletdefined near the second end of the column; a plurality of liquid distribution trays, each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes; and a plurality of down-comers configured along an inner surface of the column, each of said down-comers defining an upper section and a lower section, said upper section configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays and said lower section configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray downstream from said one of the plurality of liquid distribution trays; and introducing an ozone containing gas to the sectionalized tray column such that the ozone containing gas passes through the plurality of holes defined on each of the liquid distribution trays and comes in contact with the volume of the cyanide containing effluent held thereon to produce a treated effluent.
[0053] In an embodiment, the step of controlling pH of the cyanide containing effluent comprises mixing the cyanide containing effluent with a caustic lye for example sodium hydroxide to control the pH of the cyanide containing effluent to be within the range of 9 to 13.
[0054] In an embodiment, the process comprises: controlling any or a combination of: rate of introduction of the cyanide containing effluent to the sectionalized tray column, and rate of introduction of the ozone containing gas to the column such that the cyanide containing effluent passes through the down-comer, substantially precluding passage thereof through said plurality of holes defined on the liquid distribution trays.
[0055] In an embodiment, the process is a continuous process. In an embodiment, the cyanide containing effluent has a cyanide content ranging from 2 ppm to 30 ppm. In an embodiment, the ozone containing gas has an ozone concentration ranging from 5% to 40% preferably 5% to 15%. In an embodiment, the treated effluent has a cyanide content ranging from 0.01 ppm to 0.5 ppm. In an embodiment, the treated effluent has a cyanide content ranging from 0.01 ppm to 0.2 ppm. In an embodiment, the cyanide content in treated effluent according to the present invention is reduced to less than about 0.2 ppm.
[0056] FIG. 3 illustrates an exemplary flow chart illustrating a process for treatment of a cyanide containing effluent, in accordance with an embodiment of the present disclosure. As can be seen from FIG. 3, step 310 includes controlling pH of the cyanide containing effluent to be within the range of 9 to 12; step 320 includes introducing the cyanide containing effluent to a sectionalized tray column (110),said column comprising: an effluent inlet (111) defined near a first end of the column; a gas inlet (112) defined near a second end of the column; a gas outlet (113) defined near the first end of the column; a treated effluent outlet (114) defined near the second end of the column; a plurality of liquid distribution trays (115), each tray configured to hold a volume of the cyanide containing effluent and defining a plurality of holes (116); and a plurality of down-comers (117) configured along an inner surface of the column, each of said down-comers defining an upper section (117-1) and a lower section (117-2), said upper section (117-1) configured to be in fluidic communication with a volume of the cyanide containing effluent held on one of the plurality of liquid distribution trays (115a) and said lower section (117-2) configured to be in fluidic communication with a volume of the cyanide containing effluent held on a liquid distribution tray (115b) downstream from said one of the plurality of liquid distribution trays; and step 330 includes introducing an ozone containing gas to the sectionalized tray column (110) such that the ozone containing gas passes through the plurality of holes (116) defined on each of the liquid distribution trays (115) and comes in contact with the volume of the cyanide containing effluent held thereon to produce a treated effluent.
[0057] While the foregoing description discloses various embodiments of the disclosure, other and further embodiments of the invention may be devised without departing from the basic scope of the disclosure. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.
[0058] A system having sectionalized tray column having 8 liquid distribution trays, of design as shown in FIG. 1, was constructed and used for below experiments. Five samples of cyanide containing effluents were taken and passed through the column continuously. Table 1 below provides details of various parameters and analysis of cyanide ions present in the treated effluent leaving the column at specified time periods.
Table 1: Parameters and analysis of cyanide ions present in the treated effluents
Parameter Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
Effluent hold up volume in column (lit) 0.8 0.8 0.8 0.8 0.8
Cyanide content in effluent (ppm) 24.94 18.13 21.06 18.01 21.07
pH of effluent 11.51 10.68 11.83 11.48 11.00
TDS of effluent (ppm) 5100 3030 7650 3030 5780
Flow rate of the effluent (lit/min) 0.08 0.08 0.08 0.08 0.08
Ozone flow rate (lit/min) 0.50 0.50 0.50 0.50 0.50
Residence time (min) 10.70 10.70 10.70 10.70 10.70
Ozone generation rate (gm/hr) 0.95 1.04 1.46 1.50 1.52
Ozone escape rate (gm/hr) 0.16 0.28 0.19 0.20 0.34
Efficiency (%) 83 73 87 87 78
Mole ratio (O3 : CN-) 3.81 5.00 7.26 8.69 6.74
Analysis of cyanide(CN --) content of treated effluent
Time(hrs) CN- (ppm)
0.00 24.94 18.10 21.06 18.01 21.07
0.50 0.00 0.00 0.50 0.12 0.73
1.00 0.00 0.00 2.12 0.12 0.28
1.50 0.00 0.00 1.81 0.09 0.14
2.00 0.00 0.00 3.16 0.14 0.12
2.50 0.00 0.00 4.58 0.00 0.11
3.00 0.00 0.08 4.31 0.00 0.09
3.50 0.00 0.10 0.13 0.12 0.12
4.00 0.00 0.00 0.12 0.11 0.11
4.50 0.00 0.00 0.00 0.12 0.15
5.00 0.00 0.00 0.00 0.12 0.10
5.50 0.00 0.08 0.09 0.09 0.08
6.00 0.00 0.08 0.00 0.12 0.03
6.50 0.00 0.09 0.00 0.12 0.10
7.00 0.00 0.00 0.00 0.11 0.09
7.50 0.00 0.06 0.00 0.09 0.07
Composite analysis 0.09 0.22 0.07 0.07 0.15

[0059] A pilot scale system having sectionalized tray column with 8 liquid distribution trays, of design as shown in FIG. 1, was constructed and used for below experiments. Two samples of cyanide containing effluents were taken and passed through the column continuously. Table 2 below provides details of various parameters and analysis of cyanide ions present in the treated effluent leaving the column at specified time periods.
Table 2: Parameters and analysis of cyanide ions present in the treated effluents
Parameter Sample 5 Sample 6
Effluent hold up volume in column (lit) 20.5 20.5
Cyanide content in effluent (ppm) 23.9 20.5
pH of effluent 12.6 13.1
TDS of effluent (ppm) 5500 3300
Flow rate of the effluent (lit/min) 111.82 105
Ozone flow rate (lit/min) 383.7 309.5
Residence time (min) 11.0 11.7
Ozone generation rate (gm/hr) 34.5 27.9
Ozone escape rate (gm/hr) 2.42 2.10
Efficiency (%) 93 92
Mole ratio (O3 : CN-) 7 7
Analysis of cyanide(CN --) content of treated effluent
Time (hours) CN- (ppm)
0.0 23.9 20.5
0.5 0.00 0.00
1.0 0.00 0.00
1.5 0.09 0.00
2.0 0.10 0.00
2.5 0.00 0.00
3.0 0.00 0.06
3.5 0.15 0.12
4.0 0.00 0.11
4.5 0.17 0.00
5.0 0.00 0.00
5.5 0.00 0.03
6.0 0.06 0.08
6.5 0.00 0.05
7.0 0.11 0.00
7.5 0.05 0.02
8.0 0.00 0.00
Composite analysis 0.09 0.11

[0060] As can be seen from Table 1 and 2 above, the system and method of the present disclosure affords removal of 90% - 95% cyanide (CN-) from the cyanide containing effluents within short span of time. It could further be noted that the system and method of the present disclosure is amenable to treatment of cyanide containing effluents having varying amounts of cyanides, while affording generation of treated effluents having cyanide content less than about 0.2 ppm.

ADVANTAGES OF THE PRESENT INVENTION
[0061] The present disclosure provides a system for treatment of a cyanide containing effluent that is efficacious, simple to operate and cost effective.
[0062] The present disclosure provides a method for treatment of a cyanide containing effluent that is efficacious, simple to operate and cost effective.
[0063] The present disclosure provides a system and method for treatment of a cyanide containing effluent that can be implemented at an industrial scale.
[0064] The present disclosure provides a method for treatment of a cyanide containing effluent that affords treated effluents meeting the discharge standards as prescribed by the Pollution Control Boards.
[0065] The present disclosure provides a method for treatment of a cyanide containing effluent that does not make use of hazardous chemicals.
[0066] The present disclosure provides a method for treatment of a cyanide containing effluent that is less time consuming.
[0067] The present disclosure provides a method for treatment of a cyanide containing effluent that precludes generation of additional sludge after oxidation of cyanide content of the effluent.