WO2012123965A2

WO2012123965A2 - Potentised coagulant dose generator

Info

Publication number: WO2012123965A2
Application number: PCT/IN2012/000136
Authority: WO
Inventors: Prasanna DESHMUKH
Original assignee: Deshmukh Prasanna
Priority date: 2011-03-01
Filing date: 2012-02-29
Publication date: 2012-09-20
Also published as: WO2012123965A3

Abstract

A method for generating a potentised coagulant solution which accelerates coagulation in water containing high organic contaminants is disclosed. The method comprises electrolyzing an aqueous solution of a coagulant compound to provide a chemical complex with at least one hydroxyl group.

Description

POTENTISED COAGULANT DOSE GENERATOR

FIELD OF DISCLOSURE

The present disclosure relates to water and wastewater treatment.

Particularly, the present disclosure relates to a coagulant for water and wastewater treatment and method thereof.

BACKGROUND

Water and wastewater treatment involves the steps of removing organic and inorganic impurities from the water to make it suitable for disposal or use. Domestic wastewater or wastewater from pharmaceutical, food, and beverage industries has a very high organic content. A treatment, subject to the local, state and federal regulations and standards, must be provided to this wastewater to remove the organic contaminants, before the treated water can be disposed in sewers, waterways, or re-used.

Chemical coagulation is an important unit process in water and wastewater treatment primarily for removing suspended solids, colloidal particles and turbidity in water. Various types of coagulants are being used, wherein, the most widely used coagulants include: aluminum sulphate (Alum), polyaluminum chloride (PAC), ferrous sulphate (FeSO₄), sodium aluminate, silicon derivatives, lime, and synthetic organic polymers, where, currently, alum, PAC, and ferrous sulphate are the most preferred. The coagulants are adapted to neutralize the repulsive electrical charges (typically negative) surrounding particles allowing the particles to "stick together" forming clumps or flocks. The conventionally available coagulants have a slow speed of action and a low potency to reduce the organic content in wastewater, due to their chemical stability. Therefore, there is felt a need to provide a coagulant which has an increased speed of action and high potency, being adapted to substantially reduce the organic content of wastewater in lesser time.

OBJECTS OF THE DISCLOSURE

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:

An object of the present disclosure is to provide a method and a device thereof for generating a potent coagulant for water and wastewater treatment.

Another object of the present disclosure is to provide a coagulant which is highly potent at removing organic impurities from water and wastewater.

Yet another object of the present disclosure is to provide a coagulant for water and wastewater treatment which can be produced on-site or off-site in very little time.

Still another object of the present disclosure is to provide a coagulant for water ¾nd wastewater treatment which reduces the number of microorganisms.

One more object of the present disclosure is to provide a coagulant for water and wastewater treatment which is easy-to-make.

Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present invention. SUMMARY

In accordance with the present disclosure, there is provided a method for generating a potentised coagulant solution which accelerates coagulation in water containing high organic contaminants, said method including the step of electrolyzing an aqueous solution of a coagulant compound to provide a potentised coagulant solution comprising a chemical complex with at least one hydroxy 1 group.

Typically, in accordance with the present disclosure, the method includes the step of electrolyzing the aqueous solution of the coagulant compound in an electrolytic cell comprising a pair of electrodes selected from iron, titanium, aluminum, Boron-Doped Diamond (BDD) and gas diffusing.

Preferably, in accordance with the present disclosure, the method includes the step of enhancing the electrolysis process by placing an anion exchange membrane between the pair of electrodes to define an anolyte section and a catholyte section, wherein the aqueous solution of the coagulant compound is received in the anolyte section and sodium chloride solution is received in the catholyte section.

Typically, in accordance with the present disclosure, the coagulant compound is ferrous sulfate (FeSO₄) and the chemical complex so formed is FeSO₄(OH)_n, wherein n > 1.

In accordance with the present disclosure, there is provided a device for generating a potentised coagulant solution, said device comprising a reactor vessel having a pair of spaced apart electrodes connected to a DC power source, wherein said electrodes are fitted in an enclosed frame adapted to define a selective flow path for preventing short-circuiting of an incoming aqueous solution of a coagulant compound, thereby providing optimum electrolysis of the aqueous solution to obtain a potentised coagulant solution.

Typically, in accordance with the present disclosure, said electrodes are Boron-Doped Diamond (BDD) electrodes.

Preferably, in accordance with the present disclosure, said enclosed frame is a PVC frame held by metal oxide coated titanium contacts.

Typically, in accordance with the present disclosure, said electrodes are separated by means of plastic spacers.

Alternatively, in accordance with the present disclosure, an anion exchange membrane is positioned between said electrodes to define an anolyte section and a catholyte section.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The disclosure will now be described with the help of the non-limiting accompanying drawings, in which,

Figure 1 illustrates a schematic representation of an embodiment of the arrangement for generating the potentised coagulant solution for water and wastewater treatment in accordance with the present disclosure;

Figure 2 illustrates a schematic representation of the device for generating the potentised coagulant solution in accordance with the present disclosure; and Figure 3 illustrates a schematic representation of another embodiment of the arrangement for generating the potentised coagulant solution for water and wastewater treatment in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The present disclosure will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the disclosure.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

The description herein after, of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. The present disclosure envisages a method for generating a potentised coagulant solution for accelerating coagulation in water and wastewater treatment. The potentised coagulant solution of the present disclosure can be produced on-site or off- site in a very short duration and provides up to 90 % COD reduction and also gives a reduction in the microorganisms in the water and wastewater. The potentised coagulant solution of the present disclosure can be used for treating wastewater having high organic content such as domestic sewage, industrial wastewater from pharmaceutical, dyeing, food, and beverage industries, drinking water, ground water, and the like. Further, the present disclosure provides a device for generating the potentised coagulant solution, where the size of the device may be varied as per the application requirements.

Referring to Figure 1, therein is illustrated a preferred embodiment of an arrangement for generating the potentised coagulant solution in accordance with the present disclosure, the arrangement is generally referred by numeral 100. The device is illustrated in Figure 2, generally represented by numeral 200. A pair of spaced-apart Boron-Doped Diamond (BDD) electrodes comprising a BDD anode 104 and a BDD cathode 102 connected to a DC power source is placed in a reactor vessel. The electrodes are fitted in an enclosed frame 204 and supported on a gasket 202 being adapted to define a selective flow path for preventing short-circuiting of an incoming aqueous solution 108 of a coagulant compound, thereby providing optimum electrolysis of the aqueous solution. The BDD cathode 102 and the BDD anode 104 are separated by means of plastic spacers. The enclosed frame 204 is a PVC frame held by metal oxide coated titanium contacts.

Referring to Figure 1, ferrous sulphate (FeSO₄) is continuously pumped by pumping means 109 through supply line 108 along with distilled water which is carried through supply line 106, in the reactor vessel. A DC current, represented by numeral 113 in Figure 1, is passed through the electrodes which results in the formation of hydroxyl (OH) radicals at the BDD anode and free radicals (H) at the BDD cathode. The OH radicals, represented by numeral 110, generated at the BDD anode 104, react with the ferrous in the FeSO₄-distilled water solution as shown in (1). The bivalent ferrous is oxidized and converted to trivalent ferric resulting in the formation of a Fe complex (typically, FeSO₄OH).

The reaction is as follows:

FeSO₄ + OH → FeSO₄OH — (1)

The free radicals, represented by numeral 112, generated at the BDD cathode 102, are highly active and further react with FeSO₄ as shown in (2).

FeSO₄ + 2H → Fe + H₂SO4 — (2)

The Fe complex (typically, FeSO₄OH) obtained at supply line 114, is used as a coagulating agent for treating water and wastewater. This Fe complex reacts with the organic contaminants in the wastewater to generate metal hydroxides, carbon dioxide, and water; the reaction is shown in (3). n(CHO) + n(FeSO₄OH) → Fe (OH)₃ + Fe (OH)₂ + CO₂ + H₂O + CHO

+ FeSO₄OH + FeSO₄ — (3)

Referring to Figure 3, is illustrated an alternative embodiment of an arrangement for generating the potentised coagulant solution in accordance with the present disclosure, the arrangement is generally referred by numeral 300. A pair of electrodes comprising an anode 302 and a cathode 304 is placed in a reactor vessel, wherein, the anode 302 is a Boron-Doped Diamond (BDD) electrode and the cathode 304 is selected from a BDD, iron, titanium, aluminum, or a gas diffusing electrode. An anion exchange membrane 306 is placed between the anode 302 and the cathode 304 to separate the anode 302 and the cathode 304 as two sections, viz., an anolyte and a catholyte. An aqueous solution of ferrous sulphate (FeSO₄) in distilled water is pumped by pumping means via supply line 310 to the anolyte section and a solution of sodium chloride (0.1 M NaCl) in distilled water is pumped by pumping means via supply line 312 to the catholyte section.

A DC current, represented by numeral 308 in Figure 3, is passed through the electrodes which results in the formation of hydroxyl (OH) radicals at the anode 302 and free radicals (H) at the cathode 304. The OH radicals generated at the anode 302, react with the ferrous in the FeSO₄ solution as shown in (4). The bivalent ferrous is oxidized to form a Fe complex (typically, FeSO (OH) ₂).

The reaction is as follows:

FeSO₄ + n(OH) + CI- → FeSO₄(OH)n + HOCl — (4)

The free radicals generated at the cathode 304, react with NaCl as shown in (5).

NaCl + OH- → NaOH + CI- — (5)

The Fe complex (typically, FeSO₄(OH)₂) so obtained is used as a coagulating agent for treating water and wastewater. This Fe complex reacts with the organic contaminants in the wastewater to generate metal hydroxides, carbon dioxide and water. Further, hypochlorous acid (HOCl), which is used for treating water and wastewater, can be produced by similarly passing a sodium chloride (NaCl) and water solution through the anolyte section. The hypochlorous acid is used for disinfecting water, removing impurity, or as a pesticide for agricultural applications.

The potentised coagulant solution of the present disclosure gives up to 90 % COD reduction, therefore, also reduces the BOD (biological oxygen demand) content substantially. Further, the coagulant of the present disclosure also helps in reducing microorganisms and bacteria in the water and wastewater. The dosage of the coagulant of the present disclosure is much less, approximately l/3^rd, compared to the dosage of the conventional coagulants used in water and wastewater treatment, under the same conditions, thereby reducing the operation cost. The coagulant of the present disclosure reacts at a high speed completing the coagulation reaction in much less time compared to the conventional coagulants and is highly efficient at removing organic contaminants from the water and wastewater.

EXAMPLES

The disclosure will now be described with reference to the following examples which only exemplify the disclosure and in no way limit the scope and ambit of the disclosure.

EXAMPLE 1

The device for generating the potentised coagulant solution was constructed as follows. A 100 cm 2 BDD anode and a 100 cm 2 BDD cathode were placed in a reactor vessel, spaced apart by plastic spacers of 4 mm thickness. The electrode assembly was held in a PVC frame by means of metal oxide coated titanium contacts. The frame had a thickness of 20 mm and a flow volume of 150 cc. The flow path was covered by 20 mm PVC plates. The reactor assembly was tightened by SS nuts and bolts. The reactor assembly had a 0.25 inch inlet and outlet threaded connections.

EXAMPLE 2

The device of Example 1 was evaluated using the following steps. A liquid feeding pump of capacity 1.8 LPM, and feed and treated water storage tanks of 10 liters each were provided. Flow meter was placed inline to measure the flow. An adjustable DC power supply having current range of 3 - 30 A and voltage of 0 - 60 V was provided. An aqueous solution of FeSO4 in distilled water was prepared by mixing 100 gms of FeSO₄ in 10 liters of water. The aqueous solution was mixed for 10 minutes to obtain a uniform solution. This aqueous solution was passed through the device of Example 1. Flow through the reactor was adjusted at 50 - 60 LPH by adjusting bypass line valve and feed line valve. The power supply was set at 12 A. At the outlet of the device, a potentised coagulant solution is generated. The potency of the coagulant can be varied by varying the flow rate of feed and the applied current. This device can be run in a batch mode when flow is high and current is low.

EXAMPLE 3

The device of Example 1 was evaluated for disinfectant generation. In this case the feed solution was sodium chloride (NaCl) in distilled water. On electrolysis, a disinfectant solution was obtained which can be used for disinfection of domestic or industrial wastewater after biological treatment. Also, the disinfectant solution can be used for disinfecting drinking water, surface water, washing fruits and vegetables or even for swimming pool disinfection.

TECHNICAL ADVANTAGES

A method for generating a potentised coagulant solution for accelerating coagulation in water and wastewater treatment, as described in the present disclosure has several technical advantages including but not limited to the realization of:

• the method provides a potentised coagulant solution which is highly powerful at removing organic impurities from water and wastewater; up to 90% COD removal can be obtained in very little time using the coagulant of present disclosure; • the method of the present disclosure is simple and can be used to produce the potentised coagulant on-site or off-site in very little time; and

• the potentised coagulant of the present disclosure reacts with organic contaminants at a high speed thereby completing the coagulation reaction in much less time compared to the conventional coagulants.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression "at least" or "at least one" suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results.

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the invention as it existed anywhere before the priority date of this application.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary. In view of the wide variety of embodiments to which the principles of the present disclosure can be applied, it should be understood that the illustrated embodiments are exemplary only. While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principle of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

Claims

CLAIMS:

1. A method for generating a potentised coagulant solution which accelerates coagulation in water containing high organic contaminants, said method including the step of electrolyzing an aqueous solution of a coagulant compound to provide a potentised coagulant solution comprising a chemical complex with at least one hydroxyl group.

2. The method as claimed in claim 1, which includes the step of electrolyzing the aqueous solution of the coagulant compound in an electrolytic cell comprising a pair of electrodes selected from iron, titanium, aluminum, Boron-Doped Diamond (BDD) and gas diffusing.

3. The method as claimed in claim 2, which includes the step of enhancing the electrolysis process by placing an anion exchange membrane between the pair of electrodes to define an anolyte section and a catholyte section, wherein the aqueous solution of the coagulant compound is received in the anolyte section and sodium chloride solution is received in the catholyte section.

4. The method as claimed in claim 1, wherein the coagulant compound is ferrous sulfate (FeSO₄).

5. The method as claimed in claim 1, wherein the chemical complex is FeSO₄(OH)_n, wherein n > 1.

6. A device for generating a potentised coagulant solution, said device comprising a reactor vessel having a pair of spaced apart electrodes connected to a DC power source, wherein said electrodes are fitted in an enclosed frame adapted to define a selective flow path for preventing short-circuiting of an incoming aqueous solution of a coagulant compound, thereby providing optimum electrolysis of the aqueous solution to obtain a potentised coagulant solution.

7. The device as claimed in claim 6, wherein said electrodes are Boron-Doped Diamond (BDD) electrodes.

8. The device as claimed in claim 6, wherein said enclosed frame is a PVC frame held by metal oxide coated titanium contacts.

9. The device as claimed in claim 6, wherein said electrodes are separated by means of plastic spacers.

10. The device as claimed in claim 6, wherein an anion exchange membrane is positioned between said electrodes to define an anolyte section and a catholyte section.