Claims:
1. A process comprising treatment of effluent by treating effluent with calcium hypochlorite.

2. The process as claimed in claim 1 wherein said process comprises in-situ generation of calcium hypochlorite for treating the effluent.

3. The process as claimed in claim 1 comprises adjusting pH of the effluent in the range from 10.5 to 12.5 and mixing with base to obtain a first treated mixture.

4. The process as claimed in claim 3 wherein treatment is carried out for a time period ranging from 20 minutes to 120 minutes at a temperature ranging from 25°C to 35°C.

5. The process as claimed in claim 3 further comprises mixing first treated mixture with chlorine for a time period ranging from 20 minutes to 120 minutes at a temperature ranging from 55°C to 85°C to obtain a second mixture.

6. The process as claimed in claim 5 further comprises filtering the mixture to obtain a treated effluent fit for discharge.

7. The process as claimed in claim 1 wherein said effluent is generated during production of Pendimethalin.

8. The process as claimed in claim 1 wherein said effluent before treatment having COD in the range of 10000 to12000 ppm, TSS <100 ppm, TDS content about 40000 ppm.

9. The process as claimed in claim 1 wherein the treated effluent fit for discharge having COD less than 250 ppm, TDS content in the range of about 10 to 15% TSS content less than 100 ppm, BOD content below detection limit.

10. The process as claimed in claim 1 is operated in a continuous mode in continuously stirred tank reactor.
, Description:TECHNICAL FIELD
[0001] The present disclosure pertains to the technical field of effluent treatment. In particular, the present disclosure relates to an improved process for treatment of effluents generated during production of Pendimethalin.

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] Pendimethalin is an herbicide of the dinitro-aniline class used in pre-emergence and post-emergence applications to control annual grasses and certain broadleaf weeds. It inhibits cell division and cell elongation. Currently, it is one of the most widely used and accepted pre-emergent herbicides in the urban residential environment. With increase in demand, there has been a sharp rise in the production of Pendimethalin over the years. Numerous methods were adopted by the scientists and researchers for the synthesis of Pendimethalin with high yield and purity. However, one of the main challenges is generation of effluents during the process of synthesis. Larger the number of reaction steps and requirement of purity of pendimethalin more is the waste generated. Direct discharge of such untreated effluent containing impurities and other side-products is not suitable, since it gives rise to various environmental concerns, such as the pollution of surface and groundwater resources. Accordingly, need is felt for the treatment of effluents generated during the production of Pendimethalin.
[0004] Numerous methods have been proposed so far directed towards improved methods of treatment of effluents generated during the production of pendimethalin, either to remove the pendimethalin and related products from the discharge or to minimize the amount thereof in an efficient manner, and sometimes both. However, these processes use bioreactors and the cost is too high. Other degradation methods like fenton, anaerobic degradation etc. are also reported in the literature, however, none of the current approaches/methods seem to satisfy the existing needs.
[0005] There is therefore a need in the art to develop a new and improved process of treatment of effluents generated during production of Pendimethalin that may overcome the limitations associated with the conventional processes and provide an effluents/discharge free of any impurities or side-products at reasonable cost.
[0006] The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.
[0007] 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
[0008] It is an object of the present disclosure to provide a process for treatment of effluents generated during production of Pendimethalin that overcomes one or more limitations associated with the conventional methods.
[0009] It is an object of the present disclosure to provide a process for treatment of effluents generated during production of Pendimethalin that is cost effective.
[0010] It is an object of the present disclosure to provide a continuous process for treatment of effluents generated during production of Pendimethalin that can be implemented at an industrial scale.
[0011] It is an object of the present disclosure to provide a process for treatment of effluents generated during production of Pendimethalin that precludes need of bioreactors.
[0012] It is an object of the present disclosure to provide a process for treatment of effluents generated during production of Pendimethalin that affords effluents that can be directly discharged.

SUMMARY OF INVENTION
[0013] The present disclosure pertains to the technical field of effluent treatment. In particular, the present disclosure relates to an improved process for treatment of effluents generated during production of Pendimethalin.
[0014] An aspect of the present disclosure relates to a process for treatment of effluents generated during production of Pendimethalin, the process comprising the steps of: mixing the effluents generated during production of Pendimethalin with calcium hydroxide in a first reactor to generate a first mixture; adjusting pH of the first mixture to a pH ranging from 10.5 to 12.5; stirring the first mixture in said first reactor for a time period ranging from 20 minutes to 120 minutes at a temperature ranging from 25°C to 35°C to obtain a first treated mixture; mixing the first treated mixture with chlorine gas in a second reactor under stirring to obtain a second mixture; adjusting pH of the second mixture to a pH ranging from 5 to 8; stirring the second mixture in said second reactor for a time period ranging from 20 minutes to 120 minutes at a temperature ranging from 55°C to 85°C to obtain a second treated mixture; and subjecting the second treated mixture to filtration to obtain sludge, and a filtrate fit for discharge.
[0015] In an embodiment, the effluents generated during production of Pendimethalin comprise spent treated effluent and/or aqueous effluent and/or RVDF ML. (Rotary Vacuum Drum Filter Mother liquor- generated from other process). Spent treated effluent and aqueous effluent is generated during the synthesis of Pendimethalin.
[0016] In an embodiment, the effluents generated during production of Pendimethalin comprises traces of xylene, nitroso, HCl, ketone containing compounds, heavy metal not detectable, COD ~10000-12000 ppm, TSS <100 ppm, TDS ~ 40000 ppm and BOD is not detectable.
[0017] In an embodiment, the filtrate which is fit for discharge comprises COD less than 250ppm, and TDS: ~10 to 15% , TSS <100 ppm, BOD: Below detection limit, other parameters are within statutory norm specified by state pollution control board. In an embodiment, any or a combination of the first reactor and the second reactor are continuously stirred tank reactor (CSTR). In an embodiment, the process is operated in a continuous mode.
[0018] In an embodiment, calcium hydroxide is mixed with the effluents in the first reactor in an amount ranging from 0.5 to 3 MT (Metric ton)- preferably 1.6 MT per 10 KL of the effluents. In an embodiment, the first treated mixture is mixed & in the second reactor, Chlorine is added in an amount ranging from 1.1 to 1.2 MT to preferably 1.15 MT per 10 KL of the first treated mixture. In an embodiment, the second reactor is configured to allow egress of excess chlorine gas. In an embodiment, the second treated mixture is subjected to filtration in _filter press. However, other advance filtration equipment such as Agitated nutch filter, leaf filter, basket centrifuge etc can be used.
[0019] 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
[0020] 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.
[0021] FIG. 1 is a schematic illustrating a process for treatment of effluents generated during production of Pendimethalin, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.”
[0026] 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.
[0027] 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.
[0028] The term/expression mixed process effluent and RVDF mother liquor “effluents generated during production of Pendimethalin” as used herein throughout the present disclosure denotes the effluent containing impurities such as xylene, nitroso, HCL, ketone etc. generated during the production of Pendimethalin. Typically, various methods for production of Pendimethalin are known in the art and the process disclosed in the present disclosure is applicable for treatment of effluents generated during such methods of synthesis of Pendimethalin.
[0029] The term/expression “spent treated effluent” as used herein throughout the present disclosure denotes the treated effluents such as HCl neutralized effluents having pH ranging from about 7.5 to 8.
[0030] The term/expression “aqueous effluent” as used herein throughout the present disclosure denotes an effluent generated during the process of pendimethalin, which is considered as aqueous effluent. (other Aqueous except Spent HCL).
[0031] The term/expression “filtrate fit for discharge” as used herein throughout the present disclosure denotes the discharge that meets the effluent standards prescribed by the Pollution Control Board such as BOD (Biochemical oxygen demand), COD (Chemical Oxygen Demand) etc. In an instance the filtrate fit for discharge has COD of 250 ppm or below.
[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. Notwithstanding 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 invention aimed to provide a cost effective and environment friendly process to treat the effluent of unwanted compounds which is fulfilled by calcium hypochlorite treatment, this process significantly reduces COD after the treatment.
[0039] The present disclosure mainly pertains to the technical field of effluent treatment. In particular, the present disclosure relates to an improved process for treatment of effluents generated during production of Pendimethalin.
An aspect of the present disclosure relates to a process for treatment of effluents generated during production of Pendimethalin.
Accordingly, the present invention provides a process comprising treatment of effluent generated during production of Pendimethalin, by treating effluents with calcium hypochlorite.
The present process comprises in-situ generation of calcium hypochlorite for treating the effluent.
[0040] In an embodiment the process for treatment of effluent generated during production of pendimethanlin is subjected to calcium hypo treatment to make it suitable for discharge without any further treatment. The treated effluent according to the present invention is having COD < 250 ppm, TDS: ~10 to 15%, TSS <100 ppm and BOD: below detection limit.
In an embodiment, the process comprising the steps of: mixing the effluents generated during production of Pendimethalin with base in a first reactor to generate a first mixture; adjusting pH of the first mixture to a pH ranging from 10.5 to 12.5; stirring the first mixture in said first reactor for a time period ranging from 20 minutes to 120 minutes at a temperature ranging from 25°C to 35°C to obtain a first treated mixture. The base used is selected from calcium hydroxide, sodium hydroxide, sodium carbonate, sodium bicarbonate or magnesium hydroxide. Preferably base used is calcium hydroxide. The first treated mixture is further contacted with chlorine in any form in a second reactor (calcium hypo treatment) under stirring to obtain a second mixture; alternatively ClO2 can also be used; adjusting pH of the second mixture to a pH ranging from 5 to 8; stirring the second mixture in said second reactor for a time period ranging from 20 minutes to 120 minutes at a temperature ranging from 55°C to 85°C to obtain a second treated mixture; and subjecting the second treated mixture to filtration to obtain sludge, and a filtrate suitable for discharge.
[0041] The present process eliminates use of bioreactors and the effluent treatment cost according to the present invention is reduced to half than the treatments by conventional methods. In an embodiment, the process comprises the steps of: mixing the effluents generated during production of Pendimethalin with calcium hydroxide in the first reactor to generate the first mixture; adjusting pH of the first mixture to a pH ranging from 11 to 12; stirring the first mixture in said first reactor at a rate ranging from 50 RPM to 200 RPM for a time period ranging from 40 minutes to 80 minutes at room temperature preferably at a temperature ranging from 25°C to 30°C to obtain a first treated mixture; mixing the first treated mixture with chlorine gas in the second reactor under stirring to obtain the second mixture; adjusting pH of the second mixture to a pH ranging from 6 to 7; stirring the second mixture in said second reactor at a rate ranging from 50 RPM to 200 RPM for a time period ranging from 40 minutes to 80 minutes at a temperature ranging from 60°C to 75°C to obtain the second treated mixture; and subjecting the second treated mixture to filtration to obtain sludge, and the filtrate fit for discharge.
[0042] The present process involves in-situ generation of calcium hypochlorite for treating the effluent thereby making the process efficient and commercially viable.
[0043] In an embodiment, the effluent generated during production of Pendimethalin comprises xylene, nitroso, HCL, ketone containing compounds etc., heavy metal- not detectable, COD in the range of 10000-12000 ppm, Total suspended Solid (TSS) <100 ppm, Total dissolved solid (TDS) ~ 40000 ppm, BOD is not detectable and pH is 8-10.
[0044] In an embodiment, the filtrate fit for discharge comprises COD < 250 ppm, TDS: ~10 to 15% , TSS <100 ppm, BOD: not detected.
[0045] In an embodiment, any or a combination of the first reactor and the second reactor are continuously stirred tank reactor (CSTR). Alternatively, any other reactor with the provision of stirring, as known to persons skilled in the art, can also be utilized to serve its intended purpose as laid down in embodiments of the present disclosure.
[0046] In an embodiment, the process is operated in a continuous mode. Alternatively, the process of the instant disclosure can be operated or run in a batch mode.
[0047] In an embodiment, calcium hydroxide is mixed with the effluents in the first reactor in an amount ranging from 0.5 tons to 3.5 tons per 10 KL of the effluents. In an embodiment, calcium hydroxide is mixed with the effluents in the first reactor in an amount ranging from 0.75 tons to 1.5 tons per 10 KL of the effluents.
[0048] In an embodiment, the first treated mixture is mixed with chlorine gas in the second reactor in an amount ranging from 1.1 tons to 1.2 tons per 10 KL of the first treated mixture. In this step effluent is subjected to calcium hypo treatment which comprises in-situ generation of calcium hypo chlorite. In an embodiment, the second reactor is configured to allow egress of excess chlorine gas.
[0049] In an embodiment, the second treated mixture is subjected to filtration in filter filter press. However other advance filtration equipment such as Agitated nutch filter, leaf filter, basket centrifuge etc can be used.
[0050] However, it should be appreciated that any other filtration assembly, as known to persons skilled in the art can also be utilized to effect separation of sludge.
[0051] The present disclosure provides a continuous process for treatment of effluents generated during production of Pendimethalin that can be implemented at an industrial scale affording direct discharge of filtrate into the environment. The filtrate generated for discharge meets all the requirements of Pollution Control Board discharge norms and Chemical Oxygen Demand (COD) of the filtrate is well below the allowed limit of 250 ppm.
[0052] The process for effluent treatment according to the present invention is illustrated in following embodiments, but not limited to, the subsequent description and the figures/drawings referred therein.
[0053] Referring to FIG. 1, an exemplary schematic illustration of a process for treatment of effluents generated during production of Pendimethalin, in accordance with an embodiment of the present disclosure.
[0054] As can been seen in FIG. 1, the effluents generated during production of Pendimethalin are fed into the first reactor 110 defining one or more feeding lines 102 (through which effluent, aqueous effluent, (calcium hydroxide is introduced in the first reactor), a stirrer 104 or such other mechanism that affords stirring of the reaction mass, an outlet 106 (through which first treated mixture is taken out from the first reactor 110 and fed to second reactor 120), and one or more outlets for the gas(es) 108 generated during the course of reaction. Any conventional reactor known to persons skilled in the art may be used, for example, continuously stirred reactor (CSTR), glass lined reactor (e.g. MSGL reactor) and the likes. In an embodiment calcium hydroxide is mixed with the effluents in the first reactor in an amount ranging from 0.5 MT to 3.5 MT per 10 KL of the effluents. In an embodiment the first treated mixture is mixed with chlorine gas in the second reactor in an amount ranging from 1.1 MT to 1.2 MT per 10 KL of the first treated mixture.
[0055] As can also be seen from FIG. 1, a second reactor 120 is connected to the first reactor 110. The second reactor defines a gas inlet 112 and a gas outlet 114 affording entry and exit of chlorine gas, a stirrer 116 or such other mechanism that affords stirring of the reaction mass and an outlet 118, through which the second treated mixture is taken out from the second reactor 120 and fed to the holding tank 130 or filtration unit 140. The second reactor 120 is optionally connected to a holding tank 130 for holding the second treated mixture or directly to a filtration unit 140 that filters the second treated mixture to obtain sludge and a filtrate fit to discharge. Any conventional filtration unit known to a person skilled in the art may be used- for example filter press. However other advance filtration equipment such as Agitated nutch filter, leaf filter, basket centrifuge etc can be used.
[0056] The process of present invention has various advantages including (1) the overall effluent treatment time is reduced from 5 days to less than 1 day; (2) Volume handling reduced from 900 m3 to 150 m3; (3) This process provides lesser footprint area compared to conventional process; (4) Present process is simple and very cost-effective process; (5) No further processing for final filtrate is required; (6) The present process provides direct disposal of effluent making the process industrially feasible.
[0057] As described above in detail, effluents generated during production of Pendimethalin and calcium hydroxide are fed into the first reactor 110 through feeding lines 102 to generate a first mixture. The pH of the first mixture is adjusted from 11 to 12. The first mixture may be stirred using a stirrer 104 for 40 to 100 minutes at a temperature ranging from 25°C to 35°C to obtain a first treated mixture. The first treated mixture is then fed into the second reactor 120 through an outlet 106 and chlorine gas is passed through the first treated mixture via a gas inlet 112, under stirring to obtain a second mixture. The pH of the second mixture is adjusted from 5 to 7 and is stirred using a stirrer 116 for about 40 to 100 minutes at a temperature ranging from 60°C to 80°C to obtain a second treated mixture. Any excess chlorine gas is removed from a gas outlet 114 provided at the top of second reactor 120. The second treated mixture is then optionally fed into a holding tank 130 to allow it to settle for some time or is fed directly to a filtration unit 140 to filter the mixture to separate sludge 142 and a filtrate 144 which is suitable for safe discharge.
[0058] The present disclosure provides a continuous process for treatment of effluents generated during production of Pendimethalin that can be implemented at an industrial scale affording direct discharge of filtrate into the environment. The filtrate generated for discharge meets all the requirements of Pollution Control Board discharge norms and Chemical Oxygen Demand (COD) of the filtrate is well below the allowed limit of 250 ppm.
[0059] 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.
[0060] EXAMPLES
[0061] EXAMPLE - 1
[0062] The effluent generated during the production of Pendimethalin was taken. The initial pH of the effluent was from 1 to 2. The effluent was first treated with lime powder to neutralize any spent HCl present in the effluent, raising the pH of the effluent to about 7.5 to 8. This neutralized mass was filtered and referred to herein as spent treated effluent.
[0063] About 280 gm of spent treated effluent, 270 gm of aqueous effluents and 450 gm lime aqueous slurry (containing 30% lime powder aqueous solution) were fed to the first reactor (mixture having pH of around 11.5), and were continuously stirred for about 60 minutes at 27°C to obtain the first treated mixture. The first treated mixture was then fed into the second reactor, and about 108 gm chlorine gas was added/passed into first treated mixture (pH of this mixture was around 6.5) and were continuously stirred for about 60 minutes at 70°C to obtain the second treated mixture. The second treated mixture was then passed through a filtration unit that filters the mixture to separate sludge and a filtrate having COD of about 167 ppm (initial COD of first effluent was 9800ppm) fit for direct discharge without any further treatment.
[0064] EXAMPLE - 2
[0065] The effluent generated during the production of Pendimethalin was taken. The initial pH of the effluent is from 1 to 2. The effluent was first treated with lime powder to neutralize any acid in the effluent, raising the pH of the effluent to about 7.5 to 8. This mass is filtered and referred to herein as spent treated effluent.
[0066] Spent treated effluents at a rate of about 1.75 Kiloliter/hour, aqueous effluent at a rate of about 5 Kiloliter/hour and Calcium hydroxide at a rate of about 0.79 ton/hour were fed into the first reactor to obtain the first mixture. pH of this first mixture was adjusted to around 11.5 and was continuously stirred for about 60 minutes at 27°C to obtain the first treated mixture. The first treated mixture was then fed into the second reactor and chlorine was passed through this first treated mixture at the rate of 0.86 ton per hour to obtain the second mixture. pH of this second mixture was adjusted to around 6.5 and was continuously stirred for about 60 minutes at 70°C to obtain the second treated mixture. The second treated mixture was then passed through a filtration unit that filters the mixture to obtain sludge (about 0.33 ton per hour) and a filtrate (About 6.95 ton per hour) having COD of about 212 ppm (initial COD of first effluent was ~10500 ppm) fit for direct discharge without any further treatment.

ADVANTAGES OF THE PRESENT INVENTION
[0067] The present disclosure provides a process for treatment of effluents generated during production of Pendimethalin that overcomes one or more limitations associated with the conventional methods.
[0068] The present disclosure provides a process for treatment of effluents generated during production of Pendimethalin that is cost effective.
[0069] The present disclosure provides a continuous process for treatment of effluents generated during production of Pendimethalin that can be implemented at an industrial scale.
[0070] The present disclosure provides a process for treatment of effluents generated during production of Pendimethalin that precludes need of bioreactors.
[0071] The present disclosure provides a process for treatment of effluents generated during production of Pendimethalin that affords effluents that can be directly discharged.