WO2008115200A1

WO2008115200A1 - Compositions and process to remove contaminants from wastewater generated by industry and other sources

Info

Publication number: WO2008115200A1
Application number: PCT/US2007/018364
Authority: WO
Inventors: Alexander Blake; Barbara Blake
Original assignee: Alexander Blake; Barbara Blake
Priority date: 2007-03-16
Filing date: 2007-08-17
Publication date: 2008-09-25

Abstract

The treatment compositions and method are provided for the simultaneous removal of a plurality of contaminants from waste¬ water. The treatment is usually achieved in a reaction phase of only 4 minutes and a settling phase of o.5 to 2 minutes. During the treatment of the wastewater with the compositions and method of the present invention the contaminants are adsorbed into the interstitial spaces of the sludge matrix. In most cases, the sludge is stable and meets the TCLP leachate requirements without further fixation. The treated water is suitable for discharge or reuse. The sludge dewaters easily and does not require drying beds or lagoons.

Description

Compositions and process to remove contaminants from wastewater generated by industry and other sources

BY ALEXANDER BLAKE, U.S. CITIZEN

AND

BARBARA BLAKE, U.S. CITIZEN REFERENCES CITED: U.S. PATENT NO. 4,765,908

BACKGROUND OF THE INVENTION

This invention relates to the treatment of industrial wastewater to produce a sludge containing the contaminants in a stable form.

Many types of industries generate wastewater in the course of their manufacturing operation. Environmental laws regulate the permissable contaminant levels in the discharge or disposal of wastewater into natural streams, lakes, sewers, land surfaces, or underground reservoirs. In general, these environmental laws and regulations prohibit the concentration levels of the contaminants from exceeding specific limits.

Many industrial manufacturing processes produce wastewater that contain contaminants, such as oils, fats, phosphates, dyes, nitrites, nitrates, sulfides, sulfites, arsenic, heavy metals, or organic compounds which greatly exceed the prescribed limits for safe discharge or disposal. Most wastewater treatment methods produce a sludge which contains the contaminants in a highly unstable and leachable condition. Contaminants in unstable sludge may leach from the sludge into the ground water, surrounding soil and streams and therefore cause additional environmental damage.

Various methods have been proposed to treat, remove, or stabilize hazardous contaminants in wastewater. These prior methods fail to remove, in a single step, a multiplicity of contaminants in a short treatment time and low capital and treatment cost, while, in most cases, producing a sludge containing the contaminants in a non-leachable condition. For example, a particular process may remove some contaminants, but the wastewater still requires, in most cases, additional treatment steps to remove all contaminants to acceptable limits prior to a safe discharge. Other methods may remove the contaminants from the wastewater resulting in a sludge which is not stable, and which allows the contaminants to leach from the sludge into the surrounding environment. Typically, most prior treatment methods require a large capital expenditure for equipment. In short, current methods have failed to provide a fast, efficient, relatively inexpensive, and easy to operate wastewater treatment process.

The present invention obviates these problems by providing a wastewater treatment technology capable of removing a plurality of contaminants from wastewater and adsorbing and fixing same in a sludge which is stable and prevents leaching of the contaminants not to exceed the limits set forth by laws and regulations. The technology and method of the present invention achieves a high degree of contaminant removal in a fast, efficient, easy to operate and use, and relatively economical method. The present invention is applicable to a number of different industrial wastewater streams. The treatment compositions of the present invention are capable of removing a variety of contaminants, such as phosphates, nitrites, nitrates, sulfates, sulfites, arsenic, barium, heavy metals, cyanate, hexane solubles, such as oil and grease, dyes, paints, latex, and others. In most cases, the method of the present invention is capable of removing a multiplicity of contaminants in a single step treatment, without the need of repetitive treatment steps. The process of the present invention also significantly lowers organics concentrations in the wastewater as measured by the Biological Oxygen Demand (BOD) tests without having an adverse affect on the pH of the water. The present technique does not create undesirable resinous or carbon conditions in the treated water.

SUMMARY OF THE INVENTION

The present invention provides treatment compositions for the removal of contaminants from a wastewater stream. The treatment compositions comprise effective amounts of montmorillonite; calcium bentonite; sodium bentonite; one or more flocculants; a carrier-dispersing agent; and a catalyst. More specifically, the treatment composition of the present invention comprises approximately 5 to 38% of a metal salt; about 1 to 4% of a carrier-dispersing agent; about 1-3% of dicarboxylic acid; 25 to 45% of montmorillonite; 0.5 to 4% of a polyelectrolyte; about 5 to 38% of calcium oxide; and about 11 to 30% calcium bentonite or sodium bentonite or a combination thereof, depending on the wastewater to be treated.

It is to be understood that the above percentages refer to each component's percentage of the total treatment composition.

It is also to be understood that the percentages are approximations, with deviations being permitted within the scope of the invention.

The treatment method of the present invention is capable of removing a multiplicity of contaminants from wastewater. The technique or method includes the steps of adding to the wastewater, containing one or more contaminants, the composition of the present invention. The wastewater, with the treatment composition added, is agitated for approximately 4 to 5 minutes. The sludge containing the adsorbed contaminants is the allowed to settle. After completion of the settling phase the supernatant is discharged. When the supernatant discharged is completed, the sludge is transferred to a sludge dewatering device. The method of the present invention can be either a batch or continuous type process. The treatment may be performed at the temperature of the wastewater as it emanates from the wastewater source.

The treatment system employed in the present invention is relatively basic and inexpensive. The system consists of a treatment vessel, which functions as a reaction and settling tank, a high/low level control, an agitator, valves, pumps and a sludge dewatering device. The treatment vessel and the agitator are specially designed to assure a fine distribution of the treatment chemical in the wastewater. In the case of large wastewater volumes, multiple treatment vessels, operating alternately, may be used. Extensive treatment systems, with separate units for each phase of the treatment, are not necessary. In some cases, existing treatment systems may be easily modified to accomodate the chemical process of the present invention DESCRIPTION OF THE DRAWING

1. Treatment vessel

2. Fill pump

3. High/low level control

4. Agitator

5. Chemical supply bin

6. Spiral type chemical elevator

7. Weigh cell batch chemical feeder

8. Supernatant drain valve

9. Supernatant drain pump

10. Sludge drain valve

11. Sludge pump to sludge dewatering device

12. Sludge dewatering device

13. Filtrate pump

14. Treated water discharge

15. Sludge discharge to deposit

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method, process and treatment compositions of the present invention are capable" of removing a variety and mul- plicity of contaminants that emanate from diverse manufacturing and other industrial processes. Depending upon the particular contaminants in the generated wastewater, the chemical treatment composition may be altered by adjusting the percentage of one or more of the components of the treatment composition of the present invention to remove specific contaminants. As used herein, contaminants include phosphates, nitrites, nitrates, sulfates, sulfites, arsenic, barium, heavy metals, cyanate, hexane solubles, such as oil and grease, dyes, paints, latex, and others.

To remove the contaminants effectively and efficiently from wastewater, the treatment compositions comprise effective amounts of montmorillonite ; calcium bentonite or sodium bentonite or a combination thereof; one or more flocculants; a carrier-dispersing agent; and a catalyst. Preferably, the montmorillonite is a drilling gel or mud with a high silica content of at least 60%. The bentonite is preferably Southern (calcium) bentonite, Western (sodium) bentonite or a combination thereof. Preferably, the carrier-dispersing agent is sodium carbonate or silisa gel or a combination thereof. The flocculants are calcium oxide and a metal salt, such as aluminium sulfate. An adjustment of the pH, as required to remove particular contaminants, is accomplished with an adjustment of the percentage of the calcium oxide and metal salt. The preferred catalysts are a dicarboxylic acid and one or more polyelectrolytes . Preferably, the dicarboxylic acid is either adipic acid or maleic acid. Preferably, the polyelectrolyte is a nonionic polyelectrolyte . However, depending on particular contaminants in the wastewater, the polyelectrolyte may be anionic or cationic or a combination of non- ionic and anionic or cationic. The preferred percent weight of the components in the treatment composition are 25 to 45% montmorillonite, 14 to 30% bentonite, 13 to 65 flocculants, 1 to 4% carrier-dispersing agent, and 1.5 to 6% catalysts. If activated carbon is added to the treatment composition, its concentration is about 1 to 3% of the total composition. The preferred treatment compositions comprise:

(a) About 5 to 38% of a metal salt;

(b) About 1 to 4% of a carrier-dispersing agent;

(c) About 1 to 3% of dicarboxylic or carboxylic acid;

(d) About 25 to 45% of montmorillonite ;

(e) About 0.5 to 5% of one or more polyelectrolytes

(f) About 5 to 38% of calcium oxide;

(g) About 11 to 30% of bentonite.

If the montmorillonite is, for example, 35% of the total composition, the amount of each of the other components is selected to total 65% of the total composition. The total of the percentages represent 100% of the composition.

In the treatment composition, the preferred metal salt is a metal sulfate, preferably aluminum sulfate. The preferred carrier-dispersing agent is sodium carbonate or silica gel or a combination thereof. The preferred dicarboxylic or carboxylic acid is adipic acid or maleic acid. The preferred montmorillomite is a drilling gel with a high silica content of at least 60%. The polyelectrolyte is either nonionic, anionic or cationic, or a combination of anionic or anionic or cationic, depending on the contaminants to be removed from the wastewater. The preferred bentonite is southern (calcium bentonite) or western (sodium bentonite) or a combination thereof.

Depending on the contaminants to be removed, activated carbon may be added to the treatment composition.

Preferably, the treatment composition comprises the following:

(a) About 5 to 38% of a metal salt;

(b) About 1 to 4% of a carrier-dispersing agent;

(c) About 1 to 3% of dicarboxylic or carboxylic acid;

(d) About 25 to 45% of montmorillonite;

(e) About 0.5 to 5% of one or more polyelectrolytes;

(f) About 5 to 38% of calcium oxide;

(g) About 11 to 30% of bentonite.

In the preferred treatment composition, the metal salt is a metal sulfate, preferably aluminum sulfate. The preferred carrier-dispersing agent is sodium carbonate, silica gel or a combination thereof. The preferred catalysts are dicarboxylic (maleic) or carboxylic (adipic) acid. The preferred montmoril- lonite is an activated drilling gel with a silica content of at least 60%. The preferred polyelectrolyte is either nonionic, or a combination of either nonionic and anionic or nonionic and cationic. The preferred bentonite is either southern (calcium) or western (sodium) bentonite, depending on the application, or a combination thereof. If activated carbon is included in the treatment composition, the concentration is about 1 to 3%. The percentages of each component expresses the percentage of the component by weight of the total composition.

Without being bound by theory, it is believed that the metal salt, i.e. aluminum sulfate, removes small particulates, especially organic contaminants, and acts as a flocculant, coagulant and as a pH adjuster. The carrier-dispersing agent, sodium carbonate or silica gel or both, prevent caking of the composition during the treatment process or reaction phase. The dicarboxylic (maleic) acid or carboxylix (adipic) acid act as catalyst. The montmoril- lonite acts as adsorbent and binder. The polyelectrolyte (s) act as ion exchanger and catalyst and also aids in the splitting of emulsions. The calcium oxide or hydrated lime aids in the removal of small particles, and especially heavy metals by floc- culation and pH adjustment. Although other caustics may be used, it is believed that the calcium oxide or hydrated lime form hydroxides to aid in the flocculation and heavy metals removal. The bentonite, either southern or western or a combination thereof, also act as adsorbent.

It is also believed, without being bound by theory, that the sodium carbonate aids in the activation of the montmorillonite and bentonite and also acts as a precipitation aid. If activated carbon is included in the treatment composition for the removal of organic contaminants, it is removed from the wastewater along with other contaminants by the treatment composition of the present invention.

The type of. bentonite used in the treatment composition depends on the contaminants in the wastewater. Calcium (southern) has a lower swelling capacity but is effective for the removal of heavy metals, free or emulsified oils, latex, fats, and other organic or inorganic matter. Sodium Cistern) bentonite is particularly effective in the removal of nitrates, dyes, resins, cellulose, plastics, synthetic oils and others.

Without being bound by theory, the total percentage of montmorillonite and bentonite should total at least 50% of the treatment composition. It is believed that the contaminants adhered to and entrapped within the interstitial spaces of the montmorillonite and bentonite which, in most cases, prevents leaching of the contaminants from the resulting sludge in excess of allowable limits. It is believed that the montmorillonite and bentonite form a sludge matrix wich adsorbs the contaminants and prevents their leaching under natural conditions beyond acceptable limits.

The treatment composition of the present invention is prepared by adding the various components together and blending them in a solids blending apparatur to form a homogenous blend. In the preferred order of blending, the lesser components, such as the sdium carbonate or silica gel, the maleic or adipic acid and the polyelectrolyte or polyelectrolytes are blended together first to produce a homogenous blend. These pre-blended lesser components are then added to the other components as one single addition. All components are then blended until a homogenous blend of all components is achieved. Preferably, the components are of standard to fine commercial mesh. However, one or more components may vary in mesh size.

The volume (by weight) os the treatment composition for the treatment of a particular wastewater is determined through bench tests performed in a laboratory, usually a certified Environmental Testing Laboratory. Normally, the amount of treatment composition required to treat a particular wastewater scales up directly from the amount wetermined to treat the water in bench tests.

The pre-determined treatment composition is added to the wastewater which is then agitated with the added treatment composition for a short period of time, usually 4 to 5 minutes. After completion of the agitation or reaction phase, the floe is allowed to settle in the same tank. After completion of the settling phase, the supernatant is discharged into a sewer system or wherever desired, or into a holding vessel for reuse. Upon completion of the supernatant discharge, the settled sludge with the remaining water is pumped into a sludge dewatering device.

The treatment process is performed at ambient temperature. Usually, the treatment is performed at the temperature of the wastewater as it emanates from the source. Also, the treatment is performed at atmospheric pressure, or low or elevated pressure .

The treatment of the wastewater may be performed in either a batch type or continuous system. In Figure 1, a batch type system is illustrated. The wastewater generated by a manufacturing plant or other industrial source, is entered into the treatment vessel 1. When the vessel is full, the high/low level control 3 stops the fill pump 2 and signals the agitator 4 to start and the weigh cell chemical feeder 7 to dump the predetermined amount of treatment chemical into the treatment vessel 1. The wastewater with the treatment chemical added is agitated for approximately 4 minutes. When the weigh cell chemical feeder 7 is empty, a signal is send to the spiral type chemical elevator 6 to refill the weigh cell chemical feeder 7. A timer in the control panel stops the agitator 4 after the agitation or reaction phase of approximately 4 minutes. The floe with the entrapped contaminants is allowed to settle. The The required length of the settling phase is predetermined and a timer in the control panel signals the supernatant drain valve 8 to open and the supernatant drain pump 9 to pumps the supernatant from the treatment vessel 1. Upon completion of the supernatant drain, the high/low level control 3 signals the supernatant drain valve 8 to close and the supernatant drain pump 9 to stop. Simultaneously, the high/low level control 3 'signals the sludge drain valve 10 to open and the sludge pump 11 to start which pumps the sludge to the sludge dewatering device 12. After completion of the sludge discharge to the sludge dewatering device 12, which is controlled by a timer in the control panel and which is set to the predetermined time required to complete the sludge discharge, the sludge pump 11 is signaled to stop and the sludge drain valve 10 to close. At the same time, the fill pump 2 is signaled to start and fill the treatment vessel 1 to begin the next treatment cycle or batch.

It is to be understood that the apparati in Figure 1 is merely examplary of the present invention. Other appropriate apparati may be used within the scope of the present invention.

The following examples illustrate the process and compositions and the effectiveness for the removal of contaminants from wastewater. It is also to be understood that the examples are to be considered examplary and do not limit the scope of the present invention.

EXAMPLE NO. 1 ' .

A treatment composition with the components indicated in Table 1 was prepared in accordance with the present invention.

TABLE 1

Component Percentage

Sodium carbonate 2.83

Polyelectrolyte-nonionic 1.89

Magnesium carbonate 1.89

Aluminum sulfate 18.87

Montmorillonite 32.07

Calcium hydroxide 23.58

Calcium bentonite 18.87

The prepared treatment composition of Table 1 was added to a wastewater having the contaminants listed in Table 2 at a dose of 2g/l. TABLE 2

Contaminant Concentration (ug/1)

Benzoic acid 2000

Naphtalene 580

Diothylphthalate 160

N-Nitrosodiphenylamine 310

Anthrocene 200

Di -n-Butylphthalate 140

Pyrene 100

Batylbenzylphthalate 590

2-Ethylhexyl phthalate 3700

Oil/grease 1275 mg/1

TPHC 13.8 mg/1

Upon completion of a 4 minute agitation phase and a 1 minute settling phase, the treated wastewater was analyzed and found to have the contaminant concentrations shown in Table 3.

TABLE 3

Contaminant Concentration (ug/1)

Benzoic acid ND

Naphtalene 38

Diothylphthalate ND

N-Nitrosodiphenylamine 27

Anthrocene ND

Di-n-Butylphthalate ND

Pyrene ND

Batylbenzylphthalate ND

2-ethylhexyl phthalate ND TABLE 3 cont'd

Oil/grease 2 mg/1

TPHC 0.7 mg/1

EXAMPLE NO. 2

A treatment composition with the components indicated in Table 4 was prepared in accordance with the present invention.

TABLE 4

Component Percentage

Sodium carbonate 3.62

Polyelectrolyte-nonionic 2.71

Polyelectrolyte-cationic 1.36

Adipic acid .90

Magnesium carbonate 1.81

Aluminum sulfate 18.10

Montmorillonite 32.58

Calcium hydroxide 19.00

Calcium bentonite 19.91

The prepared treatment composition of Table 4 was added at a dose of 2g/l to a wastewater having the contaminants listed in Table 5 and was agitated for 3 minutes and allowed to settle for one minute.

TABLE 5

Contaminant Concentration (mg/1)

Copper, total . 14.4

Chromium, total 15.4

Nickel, total 20.8

Zinc, total 64 TABLE 5 cont'd

Phosphate, total as P 6.4

Oil and grease, soluble 1330.0

Upon the completion of a 3 minute agitation phase and a 1 minute settling phase, the wastewater was analyzed and found to have the contaminant concentrations shown in Table 6.

TABLE 6

Contaminant Concentration (mg/1)

Copper, total 1.08

Chromium, total 0.12

Nickel, total 13.8

Zinc, total 10.2

Phosphate, total as P 0.13

Oil and grease, soluble 20.0

Upon the completion of a 4 minute agitation phase and a 1 minute settling phase, the wastewater in Table 5 was analyzed and found to have the contaminant concentrations shown in Table 7.

TABLE 7

Contaminant Concentration (mg/1)

Copper, total 0.97

Chromium, total 0.02

Nickel, total 0.11

Zinc, total 0.18

Phosphate, total as P 0.1

Oil and grease, soluble 12.0

The difference between Tables 6 and 7 indicate that the 1 minute increase of the agitation phase and therefore the reaction time has significant effect in the removal of the contaminants listed in Table 5. EXAMPLE NO. 5

A treatment composition with the components indicated in Table 8 was prepared in accordance with the present invention.

TABLE 8

Component Percentage

Sodium carbonate 3.74

Polyelectrolyte-nonionic 1.87

Polyelectrolyte-anionic .93

Magnesium carbonate 1.87

Aluminum sulfate 16.82

Montmorillonite 37.38

Calcium hydroxide 18.69

Calcium bentonite 18.69

The prepared treatment composition of Table 8 was added at dosage of 2g/l to a wastewater having the contaminants listed in Table 9 and was agitated with the wastewater for 4 minutes and allowed to settle for 1 minute.

TABLE 9

Contaminant Concentration (mg/1)

Zinc 540

Boron 51.7

Suspended solids 6650

Upon completion of the 4 minute agitation phase and the 1 minute settling phase, the wastewater was analyzed and found to have the contaminant concentrations listed in Table 10. TABLE 10

Contaminant Concentration (mg/1)

Zinc 0.08

Boron 14.5

Suspended solids 26.0

EXAMPLE NO. 4

A treatment composition with the components listed in Table 11 was prepared in accordance with the present invention.

TABLE 11

Component Percentage

Sodium carbonate 4.20

Polyelectrolyte-nonionic 2.52

Polyelectrolyte-cationic .84

Aluminum sulfate 16.81

Montmorillonite 36.97

Cacium Hydroxide 19.33

Calcium bentonite 19.33

The prepared treatment composition of Table 11 was added at a dosage of .75g/l to a wastewater having the contaminants listed in Table 12 and was agitated with the wastewater for 4 minutes and was allowed to settle for .5 minute.

TABLE 12

Contaminant Concentration (mg/1)

Chromium 18.6

Copper 37.2

Iron 11.2

Zinc 22 Upon completion of a 4 minute agitation phase with an addition of .75g/l of the treatment composition of Table 11, the treated water was analyzed and found to have the contaminant concentrations shown in Table 13.

TABLE 13

Contaminant Concentration (mg/1)

Chromium .036

Copper .012

Iron *ND

Zinc *ND

*ND=non-detectable

Upon completion of a 4 minute agitation phase with an addition of l.Og/1 of the treatment composition of Table 11, the treated water was analyzed and found to have the contaminant concentrations as shown in Table 14.

TABLE 14

Contaminant Concentrations (mg/1)

Chromium .020

Copper *ND

Iron *ND

Zinc *ND

*ND=non-detectable

It is indicated that in certain cases, depending on the type of wastewater to be> treated, only a slight increase in the dosage of the treatment composition, in this case .25g/l, has an impact on the removal capabilities of the treatment composition as shown in the difference between Table 13 and 14.

Claims

WHAT IS CLAIMED IS:

1. Treatment compositions to remove one or more contaminants simultaneously from wastewater and comprising effective amounts of

(a) one or more flocculants and pH adjustment agents

(b) a carrier-dispersing agent

(c) one or more catalysts

(d) adsorbents

2. Treatment compositions per claim 1 wherein the flocculants and pH adjustment agents are a metal salt and calcium hydroxide.

3. Treatment compositions per claim 1, wherein the carrier- dispersing agents are either sodium carbonate or silica gel.

4. Treatment compositions per claim 1, wherein the catalysts are dicarboxylic acid and one or more polyelectrolytes which are either nonionic, anionic or cationic or a combination thereof.

5. Treatment compositions per claim 1, wherein the adsorbents are activated montmorillonite , sodium bentonite or calcium ben- tonite or a combination thereof.

6. Treatment compositions per calim 1, wherein the percent weight of a metal salt as a flocculant and pH adjustment agent is 5 to 38% of the total treatment composition.

7. Treatment compositions per claim 1, wherein the percent weight of the carrier-dispersing agent is 1 to 4% of the total treatment composition.

8. Treatment compositions per claim 1, wherein the percent weight of dicarboxylic acid as a catalyst is 1 to 3% of the total treatment composition.

9. Treatment compositions per claim 1, wherein the percent weight of the polyelectrolyte or polyelectrolytes as catalyst and ion exchanger is 0.5 to 4% of the total treatment composition.

10. Treatment compositions per claim 1, wherein the percent weight of montmorillonite v/ith a silica content of at least 60% as an adsorbent is 25 to 45% of the total treatment composition.

11. Treatment compositions per claim 1, wherein the percent weight of calcium oxide as a flocculant and pH adjustment agent is 5 to 38% of the total treatment composition.

12. Treatment compositions per claim 1, wherein the percent weight of the sodium bentonite or calcium bentonite or a combination thereof as adsorbent is 11 to 30% of the total treatment composition