WO1995024266A1

WO1995024266A1 - Waste treatment agent

Info

Publication number: WO1995024266A1
Application number: PCT/AU1995/000122
Authority: WO
Inventors: Gunter Heinzel; Janos Papp; Erika Schodder
Original assignee: Mosaic Tile And Pottery Co. Pty. Ltd.; Zeokeramik Kft
Priority date: 1994-03-11
Filing date: 1995-03-10
Publication date: 1995-09-14
Also published as: MX9604012A; NO963797D0; HU9602472D0; FI963550A; AU1940895A; AU704478B2; BG100890A; BG61968B1; JPH10503459A; BR9507410A; EP0671210A3; ZA952006B; DE59508404D1; EP0671210B1; FI963550A0; ATE193463T1; NO963797L; DE4408302A1; EP0671210A2; HUT77690A

Abstract

The invention is directed to the treatment of waste water and other polluted materials. A compound of the general formula: (ZO)nAln(OH)n-mClm (or of closely related empirical formula), wherein Z is derived from an aluminosilicate material, is prepared by activating the aluminosilicate material by treating with acid or by subjecting the material to ammonium ion exchange and then heating the thus activated material in the presence of an alumino compound. The preferred aluminosilicate is a zeolite-containing mineral of a clinoptilolite structure and the preferred alumino compound is polyaluminiumchloride. The resultant product is pH neutral; non-toxic; suitable for use in flotation and sedimentation tanks; destabilizes suspensions, dispersions and emulsions; can be used over a wide pH range; is amphoteric and particularly suited for the elimination of heavy metal cations and phosphate anions; reduces chemical oxygen deficiency, biological oxygen deficiency and adsorbable organic halogenated hydrocarbons; decreases the amount of sludge while simultaneously increasing dry matter content; does not swell; is economical to use; and is not harmful to the environment.

Description

WASTE TREATMENT AGENT

FIELD OF THE INVENTION

THIS INVENTION relates to the treatment of waste water and other polluted materials. In particular, it is directed to the production and use of a compound which efficiently clarifies or otherwise treats these waste materials.

BACKGROUND OF THE INVENTION

Today it is a requirement of most Government Authorities that polluted waters and other waste materials are adequately treated before their use and/or disposal. This is of particular concern when conditioning water for drinking purposes and when treating effluent generated by industry. For example, a number of industries produce harmful by-products which must be disposed of carefully without undue harm to the environment.

It is a complex task to purify polluted water because the pollutants have quite different properties, particulate sizes and reactivities; they may appear in solution, in .colloid form, as a suspension, dispersion or aerosol, in small or large particulate size.

Traditionally, treatment of these waste waters is a multi-stage process requiring separate screening, sedimentation, filtering and other tanks where the undesirable components are eliminated by ion exchange, precipitation, flocking, filtration; centrifugation, oxidization or reduction, osmosis, electrolysis etc., as well as biological removal using microorganisms.

As waste water can contain many pollutants- cations such as ammonium or heavy metals, anions such as phosphates and sulphates, hydrocarbons, fats, proteins and carbohydrates etc. - several or all of the above processes are required and it is not uncommon for ten (10) separate stages to be undertaken to meet the required water quality standards.

When treating such waste materials, consideration must be given to the choice of agents to be used as these agents themselves, and the products resulting from their use, must also not have a detrimental impact on the environment.

Conventional products for water treatment are usually iron, aluminium or calcium compounds which induce precipitation and flocking. Such inorganic coagulants have long been used as an agent for treating polluted water. Much research has been undertaken to improve the efficiency of these agents. For example, polyaluminiumchloride is a favoured coagulant in sedimentation tanks and in a method described in Japanese Unexamined Patent Publication No 60-209214 (Application No 59-65078, filed April 3, 1984) it is blended with finely divided aluminosilicate-containing minerals to provide a means for improving the time taken for sedimentation to be effected.

However, even this improved sedimentation process is but one step in the many stages usually required to adequately treat waste water and research has continued to develop new methods which have fewer stages, reduce sludge quantity and/or make it possible to reuse the sludge as a raw material in some other application. Further, research is continuing to develop more effective reagents to render the water treatment process more economical.

For example, the above-described Japanese process has been further improved and is described in Japanese Unexamined Patent Publication No 3-056104 (Application No 1-192232, filed July 25 1989). In one embodiment of this improved prior process, separate quantities of an aluminosilicate mineral, particularly one containing a zeolite, are individually treated with (1) sulphuric acid to give a product "a", (2) with hydrochloric acid followed by polyaluminiumchloride to give a product "b", and (3) with sodium hydroxide to give a product "c". The products a, b and c are then blended together in a 1:1:1 ratio to give a mixture which is then used to clarify polluted water.

While this improved process may be successful, it would appear to be (1) less economical than the previous processes as it requires three separate components to be prepared before the actual clarification agent can be prepared, leading to higher costs of raw materials and longer production times; and (2) the negative charge of the skeleton of product "b" limits its effectiveness in a cation/anion environment. It is an object of the present invention to eliminate, or at least ameliorate, one or more of the above problems and to provide an agent for the treatment of waste water and other polluted materials which is economical to produce, effective in the removal of more than one type of pollutant and which is environmentally friendly.

SUMMARY OF THE INVENTION

It has now been established that by first activating an aluminosilicate material and then blending with an alumino compound followed by the application of a heat produces an agent which meets these objectives.

Therefore, according to a first aspect of the present invention, there is provided an agent for the treatment of waste water and other polluted materials, said agent comprising a compound of the general formula:

(ZO)_nAl„(OH)„__mCl_m

or a compound of closely related empirical formula, wherein Z is derived from an aluminosilicate material.

As a second aspect of the present invention there is provided a method for the preparation of a compound of the general formula:

(ZO)„Al_n(OH)„__mCl_m or a compound of closely related empirical formula, wherein Z is derived from an aluminosilicate material,

said method comprising:

1) activating said material; and

2) heating the thus activated material in the presence of an alumino compound.

A third aspect of the present invention is a method of purifying waste water and the like, said method comprising treating the waste water and the like with a compound having the following general formula:

(ZO)_nAl_n(OH)„__mCl_m

The aluminosilicate can be a natural or synthetic material.

Preferably, the material is a zeolite-containing mineral.

Preferably, the zeolite content of the mineral is 40 to 95% by weight.

Preferably, the Si:Al ratio of the zeolite is greater than 3. More preferably, the zeolite is of a clinoptilolite structure.

Most preferably, the mineral is finely divided to a particle size of 250 microns or less.

Preferably the zeolite-containing mineral is activated by treating with acid or by subjecting said mineral to ammonium ion exchange.

More preferably, the zeolite-containing mineral is activated by treatment with hydrochloric acid.

Preferably, the alumino compound is a polyaluminium salt.

More preferably, the polyaluminium salt is polyaluminiumchloride.

Preferably, the ratio of mineral : alumino compound is in the range of 1:0.01 to 1:2 by weight.

More preferably, the ratio is 1:1 by weight.

Preferably, the activated mineral and the alumino compound are heated together at, a temperature which is in the range 100 - 600°C.

More preferably, the heating is undertaken at 300°C.

Preferably, the product of the invention is granulated to a particle size of 0.25 - 100 mm. It is important to appreciate that the product of the present invention is different from product "b" referred to above with reference to the Japanese Unexamined Patent Publication No 3-056104. In the prior process, a mere admixture is formed, not a new and chemically distinct compound as in the present invention. Further, the prior process only applies sufficient heat to achieve drying of the product. Typical drying temperatures are in the range 40 to 60°C - any higher, and the polyaluminiumchloride begins to decompose and lose its effectiveness.

In contrast, the present invention generally applies heat at a much higher temperature but for a significantly shorter duration and in a manner which avoids significant decomposition of polyaluminiumchloride to form a completely new product.

DESCRIPTION OF THE INVENTION

GENERAL EXAMPLE

A naturally occurring, acid-resistant, thermostable, zeolite-containing mineral is first finely divided by any convenient means and then activated by washing with hydrochloric acid. An aqueous polyaluminiumchloride solution is then added and the mixture is heated between 150 and 250° C with simultaneous evaporation of water. The product is then cooled relatively rapidly by passing through a spray tower. The product formed preferably has a water content of less than 10 percent by weight, more preferably less than 5 percent by weight.

Although not wishing to be bound by theory, the reaction is believed to be a dehydroxylisation between the protonated zeolite and the hydroxyl groups of partially hydrolized polyaluminium chloride.

In more detail, referring to the accompanying drawing, a mixture of a finely divided zeolite- containing mineral and an aqueous polyaluminiumchloride solution containing 30 to 70 weight percent polyaluminiumchloride is mixed in a container 1, and acidified with hydrochloric acid to a pH of at least 1.5. The mixture is fed to the upper end of a spray tower 4 via line 3 provided with a pump 2. Alternatively, these components can be fed separately to the top of the tower. The tower height is in the range of about 10 to 30 metres. For atomizing the mixture, a rotating disk 5 is provided at the top of the tower 4. From its upper to lower end, hot air is passed through the spray tower 4, as shown by arrows 6. The temperature of the air stream 6 is not more than 250°C, preferably not more than 200°C. If the temperature is significantly higher, the polyaluminiumchloride tends to decompose to aluminiurahydroxide or aluminiumoxide before the zeolite can react.

The composite product formed leaves the base of the tower 4 in solid form, as shown by arrow 7. During the passage, the water produced by the reaction evaporates (arrow 8). Due to this evaporation, the temperature of the air stream 6 decreases constantly. That is, the solid composite product 7, leaving the base of the tower 4 has a temperature of less than 100°C, preferably less than 90°C.

The residence time of the mixture in tower 4 is between 2 and 10 minutes.

The product of the present invention is believed to be of the general formula (Z-0)„Al_r.(OH)_Λ__ra(Cl)_ιn, wherein m is greater than 0. However, it is difficult to provide an exact empirical formula because the product of the invention can exist in various forms. Three examples of these forms are given below:

z - 0 Z - 0 Z - 0

\ \ \

Al - OH Al - OH Al ^■ - Cl

/ / / z - 0 Z - 0 Z - 0

\ \ \

Al - OH Al - OH Al - - Cl

/ / / z - 0 Z - 0 Z - 0

\ \ \

Al - OH Al - Cl Al - - OH

/ / / z - 0 Z - 0 Z - 0

\ \

Al - Cl Al - OH / /

Modifications to this general example are possible. For example, the mixture of activated zeolite and aqueous polyaluminiumchloride can first be dried at less than 100°C (to avoid decomposing the polyaluminiumchloride) and under vacuum if that is deemed necessary to further reduce the likelihood of the polyaluminiumchloride decomposing, and then the mixture is heated between 250 and 600°C.

The product of the invention is usually used at the rate of 0.1 g to 10 g/1 of waste water, more particularly, 0.2 to 0.5 g/1 of waste water.

SPECIFIC EXAMPLES

Example 1

A mineral containing about 60 weight percent of clinoptilolite and having a grain size of not more than 250 micron is mixed in a weight ratio of 1 : 1 with an aqueous polyaluminiumchloride solution having a polyaluminiumchloride content of about 50 weight percent. To this mixture is added hydrochloric acid, until a pH of less than 1.5 is obtained. The mixture is fed to the top of the spray tower where it is atomized by the rotating disk. Air at a temperature of 150 to 200°C is fed to the top of the spray tower. The residence time of the mixture in the tower is about 3 to 5 minutes. The solid composite product leaves the tower at a temperature of about 90 to 95°C with a water content of about 2 to 5 weight percent.

Example 2

Waste water was used from an optical plant and contained a large amount of hydrocarbons, a high value of chemical oxygen deficiency and a significant quantity of heavy metal ions, such as zinc and nickel. The product of the invention was prepared in accordance with Example 1 above and the waste water was treated with the following compovmds for comparison:

A) 1₂(S0₄)3 Aluminiumsulfate

B) Zeolite + Al₂(SO-_)₃ mixed 1 : 1

C) Zeolite + PAC mixed 1 : 1 (PAC = Polyaluminiumchloride)

D) Product according to Example 1

All analyses were conducted according to the German standard DIN.

Compounds A-D were tested at 1 g/1 of waste water and the pH adjusted to 8 with Ca(OH)₂.

After addition of the product, the waste water was stirred at 500 rpm at 18 to 20°C for 10 minutes.

The resultant precipitate was separated by filtration using a paper filter. The filtration rate was measured.

The determination of the heavy metal ion content was performed with an atomic absorption spectrometer.

The results are shown in Table I. Table I legal untreated maximum concentration mg/1

CSB* - 12800.0 4740.0 4200.0 4100.0 1800.0

KW** 10.0 1470.0 40.0 25.0 18.0 6.0

Zn 2.0 12.8 10.4 8.3 6.5 1.4

PG 0.5 3.0 2.4 1.2 0.6 < 0.5

2.4 1.6 0.9 0.4 < 0.1

1.2 1.1 0.6 0.4 < 0.1 lh 45' 48' 28" 17' 3¹ ro deficiency

untreated ion

48000.0 22300.0 18100.0 14400.0 8450.0

KW 10.0 2400.0 90.0 785.0 38.0 9.0

Fe 3.0 60.0 44.0 18.0 8.0 1.4

Filtation _ _ lh 5' 47' 38 18; rate

Example 3

Waste water from a bath for degreasing and phosphating metal was used. Products A-D were tested at 5 g/1 of waste water.

In all other respects, the same conditions and measurements were undertaken as in Example 2.

The results are shown in Table II.

The product of the invention is multi-functional. Due to the presence of anionic oxygen, it can act as an ion exchanger to absorb, for example, heavy metal cations; as it is partly protonated, it can exchange those protons to appropriately proton-acceptable groups such as those found in dyes; the aluminiumchloride groups can split off chloride anions thus exhibiting cationic properties to enable the removal of, for example, phosphate anions.

Importantly, by varying the degree of activation of the aluminosilicate component and the ratio of polyaluminiumchloride, these multi-functional properties can be adjusted to suit the waste material being heated.

By using the present invention, clarification of waste water and other polluted materials can be achieved more effectively than prior processes and offers at least the following advantages:

it is pH neutral; it is not toxic;

it is suitable for use in flotation and sedimentation tanks;

it destablizes suspensions, dispersions and 5 emulsions;

the only anion present is hydroxyl;

it can be used over a wide pH range;

it is amphoteric and particularly suited for the elimination of heavy metal cations and 10 phosphate anions;

it reduces chemical oxygen deficiency, biological oxygen deficiency and adsorbable organic halogenated hydrocarbons;

it decreases the amount of sludge while 15 simultaneously increasing dry matter content;

it does not swell;

it is economical; and

is not harmful to the environment.

Claims

CLAIMS :

1. A method for the preparation of a compound of the general formula:

(ZO)»Al_Λ(OH)»__ιnCl_ιn

or a compound of closely related empirical formula, wherein Z is derived from an aluminosilicate material,

said method comprising:

1) activating said material; and

2) heating the thus activated material in the presence of an alumino compound.

2. A method as defined in Claim 1, wherein the material is a zeolite-containing mineral.

3. A method as defined in Claim 2, wherein the zeolite content of the mineral is 40 to 95% by weight.

4. A method as defined in Claim 2 or Claim 3, wherein the Si:Al ratio of the zeolite is greater than 3.

5. A method as defined in Claim 4, wherein the zeolite is of a clinoptilolite structure.

6. A method as defined in any one of Claims 2 to 5, wherein the mineral is finely divided to a particle size of 250 microns or less.

7. A method as defined in any one of Claims 2 to 6, wherein the mineral is activated by treating with acid or by subjecting the mineral to ammonivun ion exchange.

8. A method as defined in Claim 7, wherein the mineral is activated by treatment with hydrochloric acid.

9. A method as defined in any one of Claims 1 to 8, wherein the alumino compound is a polyaluminium salt.

10. A method as defined in Claim 9, wherein the polyaluminium salt is polyaluminiumchloride.

11. A method as defined in any one of Claims 1 to 10, wherein the alumino compound is added as an aqueous solution.

12. A method as defined in any one of Claims 2 to 11, wherein the ratio of mineral:alumino compound is in the range of 1:0.01 to 1:2 by weight.

13. A method as defined in Claim 12, wherein the ratio is 1:1.

14. A method as defined in any one of Claims 2 to 13, wherein the activated mineral and the alumino compound are heated together at a temperature which is in the range 100 to 600°C.

15. A method as defined in Claim 14, wherein the temperature is 300°C.

16. A method as defined in Claim 11 wherein the activated mineral and aqueous alumino compound are heated at a temperature in the range of 150 to 250°C with the simultaneous evaporation of water.

17. A method as defined in any one of Claims 1 to 15 wherein the activated material and alumino compound are first dried at a temperature less than 100°C and then heated to a temperature between 250 and 600°C.

18. An agent for the treatment of waste water and other polluted materials, said agent comprising a compound of the general formula:

(ZO)_ΛAl_β(OH)„__IBCl_ιn

19. An agent as defined in Claim 18, when prepared by a method as defined in any one of Claims 1 to 17.

20. A method of treating waste water and other polluted materials by the application of an agent as defined in Claim 18 or Claim 19.