Claims:
1. A method for industrial effluent treatment comprising treating an untreated effluent with iron sulphate solution and purging chlorine gas for in situ formation of hypochlorous acid.

2. The process as claimed in claim 1, said process comprising the steps of
(i) feeding an untreated effluent into a reactor,
(ii) adding FeSO4 solution,
(iii) purging chlorine in an untreated effluent for in situ formation of hypochlorous acid and
(iv) separating the treated effluent.

3. The process as claimed in claim 1, wherein said purging of chlorine gas into untreated effluent is carried out with simultaneous dosing of iron sulphate solution to obtain treated effluent.

4. The process as claimed in claim 3, wherein said process comprises purging chlorine gas into the reactor material with simultaneous dosing of 15% iron sulphate solution for in situ hypochlorous acid generation for reducing the organic material in the effluent.

5. The process as claimed in claim 1, further comprises neutralization of treated effluent and separating the solids from the liquid.

6. The process as claimed in claim 1, wherein said untreated effluent hase a chemical oxygen demand (COD) content more than 1000 ppm and ammoniacal nitrogen content more than 40ppm.

7. The method as claimed in claim 1, wherein said iron sulphate solution is 10 to 20% FeSO4 solution.

8. The method as claimed in claim 1, wherein the ratio of said iron sulphate solution and said chlorine in the reaction is about 1:2.

9. The method as claimed in claim 1, wherein said treated effluent has a COD content below 500ppm and ammoniacal nitrogen content below 30ppm.

10. The method as claimed in claim 1, said method treats an effluent generated during production of an agrochemical and reduce a COD content below 500ppm.
, Description:
Field of the invention
The present disclosure relates to the technical field of treatment of industrial effluents. More specifically the present invention relates to a process of reducing Chemical Oxygen Demand (COD) and ammoniacal nitrogen content in the waste effluent generated in the agriculture industry.

Background and the prior art
In general iron-based advanced oxidation technologies, such as the Fenton process, are widely used for industrial wastewater treatment. However, this process uses chemicals such as hydrogen peroxide which is hazardous and costly. Also, wastewater sometimes contains chelating agents such as detergents, stabilizers, and masking agents for metallic ions, which have a potential to inhibit the iron-based advanced oxidation process through the masking of iron. Sodium hypochlorite as an alternative to hydrogen peroxide in Fenton process for industrial scale, Behin J, et. al., Water Research, 09 May 2017, 121:120-128, discloses that NaOCl/Fe²? process utilizing a conventional oxidant, in comparison to hydrogen peroxide, is an efficient cost effective process for Chemical Oxygen Demand (COD) removal from real wastewater, although the removal efficiency is not as high as in Fenton process; however it is a suitable process to replace Fenton process in industrial scale for wastewater involved aromatic compounds with high COD. However the use of Sodium Hypochlorite, is costly, not eco-friendly and also has stability issues.

US4769154 discloses a method for treating waste water containing solid, organic particles mixed in water for separating the particles into a sludge.

Usage of hydrogen peroxide, hypochlorite and chlorine dioxide for effluent treatment and disinfection is well known. However, none of the prior art provides a simple and economic process for treatment of effluent which provides ammoniacal nitrogen reduction along with reduction in COD via in-situ fenton like reaction.

The present invention satisfies the existing needs, as well as others, and generally overcomes the deficiencies found in the prior art.

Object of the invention
It is an object of the present invention to overcome the drawbacks of the prior art.
It is an object of the present disclosure to provide a process for treatment of effluents generated during production of agrochemicals that overcomes one or more limitations associated with the conventional methods.

It is an object of the present disclosure to provide a process for treatment of effluents generated during production of agrochemical such as propineb that is simple, economic and rapid.

It is an object of the present disclosure to provide a continuous process for treatment of effluents that can be implemented at an industrial scale.

It is an object of the present disclosure to provide a process for treatment of effluents that affords effluents that can be directly discharged.

It is another object of the present invention to complete eliminate the use of hazardous hydrogen peroxide usage for effluent treatment.

It is a yet another object of the present invention to reduce the chemical cost for effluent treatment.

Brief description of accompanying figures
Figure 1 illustrates the diagram of the process of the present invention.

Summary of the Invention
In an aspect the present invention provides a process for treatment of effluents generated during production of an agrochemical.

In another aspect the present invention provides a method for effluent treatment comprising the steps of:
(i) feeding untreated effluent batch in a reactor
(ii) purging chlorine gas into the reactor with simultaneous dosing of FeSO4 solution and
(iii) neutralizing the treated batch and separating the solids.

Typically, the present process comprises in-situ generation of hypochlorous acid by way of purging chlorine gas in effluent. According to the present process hypochlorous acid reacts with the iron (II) complex in aqueous solution. This in situ generated Hydroxyl radicals are highly reactive to oxidise the organic contaminants present in the form of COD (Chemical Oxygen Demand). In specific embodiment 80-90% reduction in COD and 80-90.5% reduction in ammoniacal nitrogen content is achieved in treated effluent.

Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

Detailed description of the invention
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.

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. The terms method and process are used synonymously.

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.”

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.

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.

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.
In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, percentage, 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.

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.

The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.

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.

The present disclosure pertains to the technical field of effluent treatment. In particular, the present disclosure relates to a process for treatment of effluents generated during production of agrochemical for example a fungicide such as propineb technical.

High efficiency effluent treatment has become increasingly important and therefore there is a long felt need for a process for wastewater treatment in effluent treatment plant.

Typically, iron-based advanced oxidation technologies, such as the Fenton process, are widely used for industrial wastewater treatment. However, the Fenton process uses chemicals such as hydrogen peroxide which is hazardous and costly. Also, the wastewater sometimes contains chelating agents such as detergents, stabilizers, and masking agents for metallic ions, which have a potential to inhibit the iron-based advanced oxidation process through the masking of iron.

Further, most of the conventional processes involve treatment of the effluent generated from the process with sodium hypochlorite for COD and ammoniacal nitrogen reduction. After this treatment the effluent is sent for discharge that meets the effluent standards prescribed by the Pollution Control Board. There is a need for modified process to eliminate the use of sodium hypochlorite, which is costly, not eco-friendly and also has the stability issue during the effluent treatment.

The present invention is directed to address above problems of masking of Iron by continuous addition of iron using iron sulfate (FeSO4) solution and complete elimination of hydrogen peroxide and sodium hypochlorite. The present invention thus provides a simple and industrially feasible process by in-situ generation of hypochlorous acid thereby overcoming the problem of iron masking. Advantageously, the present process is much faster than the analogous reaction involving hydrogen peroxide (the Fenton reaction). Moreover, the COD and ammoniacal nitrogen level in the treated effluent is reduced efficiently. Particularly the about 90% reduction in COD and ammoniacal nitrogen is achieved in the present invention. It has been found that the untreated effluent can have a chemical oxygen demand (COD) content more than 1000 ppm and ammoniacal nitrogen content more than 40ppm which when treated in accordance with the present invention brings down the COD content to below 500ppm and ammoniacal nitrogen content to below 30ppm.

According to one embodiment of the present invention there is provided a method for industrial effluent treatment comprising treating an effluent with iron sulphate solution and purging chlorine for in situ formation of hypochlorous acid. In a preferred embodiment the purging of chlorine gas into untreated effluent is carried out with simultaneous dosing of FeSO4 solution to obtain treated effluent. Such dosing may be carried out with 15% FeSO4 solution for in situ hypochlorous acid generation for reducing the organic material in the effluent.

In another embodiment, the present invention provides a method for effluent treatment comprising the steps of:
(i) feeding untreated effluent into a reactor,
(ii) preparing a batch of FeSO4 solution,
(iii) transferring the batch of step (ii) into a reactor containing effluent,
(iv) purging chlorine gas into the reactor material with simultaneous dosing of FeSO4 solution for in situ formation of hypochlorous acid to treat said effluent and
(v) neutralizing the treated effluent and separating the solid from the liquid.

In an embodiment the untreated effluent having content of COD more than 1000ppm and ammoniacal nitrogen content more than 40ppm. Such effluent is not suitable for environment and does not meet standards prescribed by the Pollution Control Board.

In an embodiment the present invention provides a simple and cost-effective method for treatment of effluent generated in the production of agrochemicals.

In an embodiment iron sulphate (FeSO4) is directly treated with effluent.

In another embodiment FeSO4 solution is prepared in an effluent or water. In preferred embodiment 10 to 20% FeSO4 solution is used in the process.

In an embodiment chlorine gas is purged at the rate of 0.4-0.5 gram/ minute.

In an embodiment the method is carried out by purging chlorine gas and continuous dosing of FeSO4 in to effluent to be treated.

In an embodiment the ratio of iron sulphate (FeSO4) and chlorine is about 1:2.

In an embodiment the treated effluent is having 86.8-90.7% reduction in COD and 83.3-97.5% reduction in ammoniacal nitrogen content.

In an embodiment neutralization step involves flowing the treated batch material into a separate container and adding sodium hydroxide solution to adjust the pH in the range of 7-9.

In an embodiment the process further comprises passing the pH adjusted treated effluent through a filtration device to separate liquid from the solids and collecting the solids from the filtration device.

In an embodiment the remaining effluent is safe for final discharge after mixing with other effluent streams and polishing treatment.

In the present invention COD content is reduced to below 500ppm preferably below 300ppm more preferably about 250 ppm and ammoniacal nitrogen content is reduced to less than 30ppm preferably about less than 15ppm, more preferably about less than 10ppm.

The present process surprisingly provides approximately 90% reduction in COD and ammoniacal nitrogen content in the effluent. Particularly, the present invention achieves 86.8-90.7% reduction in COD and 83.3-97.5% reduction in ammoniacal nitrogen content.

The present invention thus provides a continuous process for treatment of effluent wherein the COD content and ammoniacal nitrogen content in the effluent is reduced to about 90%.

According to a specific embodiment of the present invention the present effluent treatment process is preferably used to treat the effluent generated in the production of propineb.

Apart from providing high reduction in COD and ammoniacal nitrogen, the present process is highly cost effective.

Advantages of the Invention
1. Complete elimination of hazardous hydrogen peroxide usage for effluent treatment.
2. Reduction in chemical cost for effluent treatment. The proposed treatment scheme will have a saving potential of Rs.45-50/ KL effluent.
3. Reduction in effluent quantity due to elimination of Sodium hypochlorite addition (1 Kiloliter/ 6 Kiloliter of effluent).
4. The present process can be applied to other effluent streams either for complete treatment or as a pretreatment method for improving their biological treatment efficiency.

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.

EXAMPLES
Example 1
A sample of effluent generated during the production process of propineb was taken from the plant site. The initial parameters of effluent were as follows:
pH- 8.3
COD- 2800 ppm
Ammoniacal Nitrogen- 149 ppm

In the reaction vessel 900 millilitre effluent was taken and chlorine purging was started at the rate of 0.4-0.5 gram/ minute. For continuous feeding of FeSO4 during the reaction, 15% solution of FeSO4 was prepared in the effluent in a separate vessel and fed in the reaction vessel continuously during the reaction with the aid of a peristaltic pump at the rate of 1.5-1.7 millilitre /minute. Overall an optimized ratio of FeSO4 and Chlorine (1:2 respectively) was maintained during the course of reaction. For 1000 millilitre effluent (900 millilitre effluent in the reaction vessel + 100 millilitre in the form of 15% FeSO4 solution) a total of 15gram FeSO4 and 30gram chlorine gas was used. To study the reaction time course, samples were withdrawn at different chlorine dosing and analysed for COD and Ammoniacal nitrogen reduction. After completion of reaction, an aliquot of 500 millilitre reaction mass was taken and pH of this aliquot was adjusted to 8.13 using 32% caustic lye solution. For neutralization of 500 millilitre reaction mass, a total of 32.55 gram of 32% caustic lye solution was utilized. After pH adjustment, the treated reaction mass was filtered using a common lab filtration device. The wet sludge cake quantity was 20.7 gram. The parameters of treated filtrate mother liquor were as follows:
pH- 8.13
COD- 261 ppm
Ammoniacal Nitrogen- 12 ppm

The results indicate a 90.7% reduction in COD and 91.9% reduction in Ammoniacal Nitrogen. The detailed data of above-mentioned experiment and similar four other experiments is shown below tables.
Table 1A
Experiment-1 Experiment-2 Experiment-3 Experiment-4 Experiment-5
Samples Sample-1 Sample-2 Sample-3 Sample-4 Sample-5
Initial pH 8.3 8.15 8.88 12.94 12.93
Initial COD 2800 3115 2748 2984 2971
Initial AN 149 244 57 42 36
Initial TDS 66212 60242 63829 71584 67224
Effluent Vol. (ml) 1000 1000 1000 1000 1000
FeSO4 (gm) 15 15 15 15 15
Cl2 (gm) 30 30 30 30 30
FeSO4 dosing 15% FeSO4 solution prepared in effluent and continuous dosing through peristaltic pump
Cl2 purging Chlorine gas purging done till 2 times of FeSO4 qty. and in between samples withdrawn

Table 1B

Sampling COD NH3-N COD NH3-N COD NH3-N COD NH3-N COD NH3-N
Sample-1 363 * 469 * 366 * 525 * 394 *
Sample-2 326 * 419 * 345 * 372 * 373 *
Sample-3 321 * 469 * 347 * 355 * 341 *
Sample-4 246 * 443 * 326 * 324 * 368 *
Sample-5 318 12 446 6 365 6 308 9 375 6
Neutralization with 32% NaOH
Effluent Vol. (ml) 500 500 500 500 500
32% NaOH used (gm) 32.55 29 28 29.8 30.35
Sludge generated (gm) 20.7 15 16.8 15 16
Parameters after neutralization with NaOH
pH 8.13 9.57 9.23 8.33 7.66
COD ppm 261 411 347 335 315
NH3-N ppm 12 6 6 6 6
Total dissolved solid (TDS) ppm 89070 88550 84545 91530 86895
R.Chlorine ppm 9 42 0 42 4
Chloride ppm 16061 17633 13617 16236 15887
% reduction COD 90.7 86.8 87.4 88.8 89.4
% reduction NH3-N 91.9 97.5 89.5 85.7 83.3

Example 2
Experimental detail:
In the reaction vessel 900-1000 millilitre effluent was taken and chlorine purging was started at different rates. For direct FeSO4 addition 1000 millilitre effluent was taken and various quantities of FeSO4 was added (0.5-2%). For continuous feeding of FeSO4 during the reaction, 15% solution of FeSO4 was prepared in the effluent in a separate vessel and fed in the reaction vessel continuously during the reaction with the aid of a peristaltic pump at the rate of 1.5-1.7 millilitre /minute. Overall an optimized ratio up to FeSO4 and Chlorine (1:2 respectively) was maintained during the course of reaction. To study the reaction time course, samples were withdrawn at different chlorine dosing and analysed for COD. After completion of reaction sample COD was checked after neutralization and filtration using a common lab filtration device.

Table 2A

E-1 E-2 E-3 E-4
Concept of Expt 1% FeSO4 direct addition 2% FeSO4 direct addition 1.5% FeSO4 solution in water and continous dosing 2% FeSO4 solution in water and continous dosing
Initial pH 8.14 8.14 8.14 8.15
Initial COD 3033 3033 3033 2931
Initial AN 149 149 149 88
Initial TDS 70339 70339 70339 67933
Effluent Vol. (ml) 1000 1000 1000 1000
FeSO4 (gm) 10 20 15 20
Dosing Once initial dosing Drop wise (15%) Drop wise (20%)
Cl2 qty. gm COD gm COD gm COD gm COD
0.25X Fe 3 1858 5 2269
0.5X Fe 5 1270 10 1529 8 875 10 686
0.75X Fe 8 739 15 819 11 708
1X Fe 10 772 20 462 15 472 20 414
1.25X Fe 12 767 25 363 19 338 25 354
1.5X Fe 15 574 30 347 23 284 30 317
1.75X Fe 26 251 35 259
2X Fe 20 412/315 40 261 30 276 40 346
After neutralization COD 315 261 276 253
% COD reduction 90 91 91 91

Table 2B
E-5 E-6
Concept of Expt 1.5% FeSO4 solution in water and continous dosing + fast Cl2 purging (17 min WRT 2 hrs) Feed pH increased to 12 + 1.5% FeSO4 solution in water and continous dosing
Initial pH 8.15 8.15
Initial COD 2931 2931
Initial AN 88 88
Initial TDS 67933 67933
Effluent Vol. (ml) 1000 1000
FeSO4 (gm) 15 15
Dosing Drop wise (15%) Drop wise (15%)
Cl2 qty. gm COD gm COD
0.25X Fe
0.5X Fe 8 1042 8 943
0.75X Fe 11 690 11 530
1X Fe 15 734 15 356
1.25X Fe 19 453 19 299
1.5X Fe 23 346 23 330
1.75X Fe 26 387 26 268
2X Fe 30 386 30 360
After neutralization COD 300 255
% COD reduction 90 91

Result:
It is evident from above table that in all the batches at least 90% reduction in COD was achieved.