WO1992000919A1

WO1992000919A1 - Process for color removal and detoxification of waste water

Info

Publication number: WO1992000919A1
Application number: PCT/EP1990/001081
Authority: WO
Inventors: Marian Stalmasek
Original assignee: Pure 1998 Ag
Priority date: 1990-07-05
Filing date: 1990-07-05
Publication date: 1992-01-23

Abstract

The invention relates to a process for catalyzed detoxification and removal of color and undesirable compounds from contaminated liquids in the presence of an oxidant and is characterized by adding to the liquid an effective amount of a blood protein or a mixture of blood proteins as a multifunctional biocatalyst to obtain a liquid phase essentially free from toxic substances and color. The invention also relates to the use of a blood protein or a mixture of blood proteins as a multifunctional biocatalyst for catalyzed detoxification and removal of color and undesirable compounds from contaminated liquids.

Description

PROCESS FOR COLOR REMOVAL AND DETOXIFICATION OF WASTE WATER.

Hazardous wastes pose major disposal problems for all industrialised

Societes. There is a great need for effective technology, particularly since a huge amount of wastes is generated by the industry each year, which requires some degree of detoxification before it can be safely released into the environment.

The present invention relates to a catalyzed process for color removal and detoxification of liquids using blood proteins as a biocatalyst. The technology is based on the multifunctional behavior of blood proteins.

The method is very useful for water purification in the pulp and paper industry, petroleum refining, dyes, resins, plastics, iron and steel industry, coal-conversion plants and chemical industry producing toxic high colored phenolic organic pollutants which are difficult to remove by means of the technology currently available. Current methods include solvent extraction, microbial degradation, absorbtion on activated carbon, chemical oxidation, enzymatic treatment, ultrafiltration and filtration through soil, ion-exchange chromatography, lime and alum precipitation, polymeric absorbtion and electro-chemical treatment. A number of other techniques have been investigated.

A novel enzymatic color removal process has been developed, using horseradish percxidase and hydrogen peroxide (A.M. Klibanov et al: SCIENCE, 1983, Vol. 221, p. 259-260; M.G. Paice, L. Jurasek: Biotechnol. Bioeng. 1984, Vol.

26, p. 477-480). Aeration in the presence of the enzyme laccase is also Known for color removal from effluents in the pulp and paper industry (K. Forss et al : Paper and Timber, 1989, Vol. 10, p. 1108-1112). The color, in the mentioned processes, was reduced by about 85% and toxicity in average by 90%. The main problem is, however, that enzymes cannot now be produced at acceptable costs and hydrogen peroxide is difficult to use.

Various oxidation-reduction enzymes initiate reactions that generate highly reactive free radical intermediates. These intermediates can react with either the initial substrate, causing polymerization, or with other substances, leading to complexation. Said enzymes can also catalyse various chemical reactions (dehaiogenation, decarbcxylation, hydroxylation, deamination etc.).

According to JP 47032637 it is known to catalyze polymerization of

2,6-xylenci in the presence of FeCl_a and hemoglobin by blowing air into the nixture for 2 hours to give 90% of poly(2,6-dimethyl-p-phenyiene ether).

Further, from JP 8774424 it is known that a filter composed of fibres loaded with metal porphyrins can be used for oxidation of mercaptans to an odourless material.

It is also known that heavy metals are removed from industrial waste water by passing it through ion-exchange resin prepared with wood chips covered by animal blood denaturated with steam and adding hydrogen peroxide or hypochlorite as an oxidant (CN 87100511).

The present invention relates to a process for catalyzed detoxification and removal of color and undesirable compounds from contaminated liquids in the presence of an oxidant. The process is characterized by adding to the liquid an effective amount of a blood protein or a mixture of blood proteins as a multifunctional biocatalyst to obtain a liquid phase essentially free from toxic and other undesirable substances and color.

The term "blood proteins" encompasses both natural and artifically made blood proteins. Thus, the blood proteins may be derived from blood from animals or be produced by microorganisms with cloned genes using gene technology.

According to a preferred embodiment of the process of the invention natural whole blood from animals is used as the mixture of blood proteins.

As oxidant one can use air, oxygen, ozone, hypochlorite, hydrogen peroxide or any other oxidant or a combination thereof, under atmospheric or high pressure conditions. The preferred oxidant is air since all other oxidants will increase the costs of the process.

In order to enchance the process one or more of the following substances can be added to the liquid to be purified: a) chemicals creating a two phase or multiphase system, b) oils or surfactants, c) coagulation factors, d) high reactive species stabilizers, e) oxygen vectors,

f) buffers, g) catalyst activators or inhibitors, h) mediators, i) reducing agents.

The multifunctional biocatalyst used in the process of the present invention acts by catalyzing the following reactions: a) dehalogenation, b) decarboxylation, c) hydroxylation, d) polymerization, e) deamination, f) oxidation.

According to a preferred embodiment of the present process an aqueous effluent to be purified is aerated in the presence of blood proteins and in the presence of a water phase/organic phase system and an oxygen vector also added to the effluent, the blood proteins then effecting their catalytic activity at the organic phase/water interface. The process will work within broad ranges of pH (1-14) and temperature (1-120'C). The concentration of the blood proteins mixture is preferably from 1 microgram to 15 grams per liter of liquid. The amount of organic phase such as an oil added to the liquid is preferably less than 0,1. but can be greater. The exact conditions must be selected according to the particular situation and this selection is within the skill of an expert. The same is valid for the choice of oxygen vector.

The final result of the treatment of the contaminated liquid according to the process of the present invention may be strong precipitation and sedimentation. The reaction is usually completed within about 5 to 60 minutes, typically already after 30 minutes. However, in case of e.g. dechlorination reactions a precipitation will normally not occur so a separation step will be superfluous.

When applying the process of the invention for the removal of color from a bleached kraft plant effluent (see Example 1 below), the color removal was about 94-99%, usually 98%. The color removal was a true catalytic effect and not simply an absorption of color by the proteins since when bovine serum albumine (BSA) was added instead of a mixture of blood proteins, a rapid decrease of color removal was observed under the same conditions (see Figure 1) . The contents of chlorinated phenols in bleaching plant waste water decreased by more than 95%, in the presence of a flocculant (Ca⁺⁺ ions or other) by more than 58.5% (see Example 1). Before this experiment, the waste water was toxic at 55% concentration, as expressed by LC₅₀, 24 hours (AMES TEST). After the experiment the water was nontoxic. Other pollutants, such as poiychlorinated biphenyls, polychlorinated dioxins and dibenzofurans can be coprecipitated in the same step. It is necessary to mention that also the contents of amines, heavy metals, cyano ions and odour in liquid can be decreased.

Any solid phase obtained in the process can be separated by sedimentation, filtration, centrifugation, filter pressing etc. The precipitation can be improved by existing technology as for example lime coagulation, polymeric anionic or cationic precipitation, by flocculants added etc.

As mentioned above flocculants can be added to improve the precipitation. Thus, calcium ions can be used as well as inorganic salts like aluminium sulphate and anionic and cationic polymeric flocculants. The flocculant can be added to the contaminated liquid before or after aeration or addition of any other oxidant.

Our process can be used also for endotoxins removal from liquids. The efficiency of the process is over 85% and can be used in several applications (see Example 3 below).

The multifuncional biocatalyst in the form of blood proteins can be used in a two phase or multiphase system, such as a water phase/organic phase system, e.g. an oil-in-water system, or immobilized on a liquid or solid support, co-immobilized with one or more catalysts or cofactors, co-immobilized with one or more low molecular weight activators or in crosslinked form.

The biocatalyst in the form of blood proteins can be modified by limited proteolysis, and chemical and biochemical modification or replacement of iron in heme-structure. The biocatalyst used in our process can also be activated by palmityl chloride and other fatty acid derivatives, activated polyethylene glycol PEG, washing with acetate buffer etc. In the case of immobilization of blood proteins on a solid support, the invention can be used in treatment of contaminated drinking water or in food industry (milk contaminated with pesticides or antibiotics etc.).

Our process can be used in open ponds, in a tower reactor as a batch process or in a fiuidized-bed biofilm reactor using the blood proteins in immobilized form. The process can be used in pulp and paper industry, mining and coal processing industry, in textile, chemical, pharmaceutical and food industry and for treatment of hazardaous and toxic materials, heavy contaminated waters and soil ect. in case of environmental accidents.

Using the present invention at pollution sites leads to binding cf modified pollutants to soil particles or humic materials, immobilize pollutants and make them less harmful. Testing has shown that binding of toxic chemicals to humic substances tends to render them less toxic.

The advantages of the present invention is that the biocatalyst used is produced in an economically feasible way, has a broad substrate specificity and is much less sensitive than bacterial degradation to pH, concentration of toxic pollutants and temperature. Moreover, during the process highly reactive substances are produced, which allow detoxification of relatively inert pollutants coprecipitaiting it and, as has been already mentioned, heavy metals, substituted anilines, cyanide, thiocyanate and unpleasant odour is removed in one time. Immobilization of the blood proteins allows reuse of the biocatalyst. The efficiency of the process is the same or higher than in the case when enzymatic preparations are used.

The invention is further illustrated by the following non-limiting examples.

EXAMPLE 1

COLOR REMOVAL FROM B_LEACHED KRAFT PLANT EFFLUENT

To an effluent from the caustic extraction stage (E₁) of a bleached kraft plant having a pH of 8.9 and having been filtered through a 0.8 micron filter there were added 0.1% of an oil in small drops under vigorous mixing to obtain microscopic oil-in-water particles. Then 50 milligrams of animal whole blood, diluted in a physiological solution and with high affinity to the oil/water interface, were added per liter of effluent. To improve the solubility of polymerised substances dioxane was added in an amount of 0.1%. To the effluent also 0.1 grams of CaCl_a per liter was added. The reaction was initiated by blowing air through the mixture. After 60 minutes the process was stopped. The sample was centrifugated for 5 minutes at 5000 rpm. The color of the clear solution was measured at 465 nm after adjustment of pH to 7.5.

The procedure above was repeated with the exception that BSA (bovine serum albumine) was added instead of the whole blood in the same amount.

The results of these experiments are shown in Figure 1 wherein bar 1 represents the effluent before treatment, bar 2 represents the effluent ater treatment with BSA and bar 3 represents the effluent after treatment in accordance with our process. The total color removal was 94%.

EXAMPLE 2

DECHLORINATION OF CHLORINATED PHENOLIC SUBSTANCES

The procedure of Example 1 was repeated for toxicity removal experiments with first extraction stage (E₁) effluent and chlorination stage (C) effluent from a bleached kraft plant. The reduction of chlorinated aromatics was measured by standard gas chromatography analysis. The results are summarized in the table below. The total reduction of chlorinated phenolic substances was 97% and the aeration time was 60 minutes.

TABLE

Chlorinated aromatic Effluent Amount in micrograms per liter

Aeration time

0 min 60 min.

Chlorinated 380 7

phenols 67 ND

Chlorinated 160 5

catechols 1450 9

Chlorinated 1685 24

guaiacois 72 7

Chlorinated 743 63

vanillins 324 24

REMARKS : extraction stage effluent

chlorination stage effluent

ND not detected

The results are also presented in Figure 2 .

Dechlorination of a stage C bleach plant effluent having pH 2.8 was also detected by following the increase in absorbance at 280 nm in a GPC experiment. The conditions were the same as described in the procedure of Example 1, with the exception that the aeration time now was 20 minutes.

The result o f this dechlorination is presented in Figure 3 wherein the solid line represents the sample after treatment and the dotted line the sample before treatment.

EXAMPLE 3

REMOVAL OF ENDOTOXINS FROM A LIQUID

The proceture of Example 1 was repeated with a standard solution of endotoxins from E.coli bacteria (8 units/ml as measured by the Limulus method). After 60 minutes treatment, the precipitate obtained was removed by centrifugation for 5 minutes at 5,000 rpm. The endotoxin content was measured in clear solution. Result - 0.97 unit/ml corresponding to a 87% reduction. The result is also shown in Figure 4 where bar 1 represents the solution of endotoxins before treatment and bar 2 represents the solution after treatment with blood proteins.

EXAMPLE 4

MOLAR MASS DISTRIBUTION OF PHENOLIC SUBSTANCES

The procedure of Example 1 was repeated applied to waste water from a coal conversion plant. The time of treatment with blood proteins was

15 minutes. The molar mass distribution of phenolic substances was measured by CPC analysis; column: Sepharose 12; eluaπt: 0.5 N NaOH; sample was 50 times diluted.

The results are shown in Figure 5 wherein the solid line represents the sample before treatment and the dotted line the sample after treatment.

EXAMPLE 5

COPRECIPITATION OF POLYCHLORINATED BIPHENYLS

The removal of 2 ,4,5-trichlorobiphenyl (PCB) from solution was studied under the same conditions as in Example 1. A 5 ppm solution of PCB was treated in 0.01 borate buffer (pH 9.3) with 100 micrograms of natural animal whole blood per liter and 0,1% of an oil and 15 minutes blowing of air (1 lit./min) without any measurable removal of the PCB pollutant.

When the same concentration of the PCB was dissolved in the E₁ bleach plant effluent, after treatment carried out as above 92% of the PCB pollutant was removed by coprecipitation. The reaction is very fast since PCB has high affinity to lipophilic substances. Bovine serum albumine (BSA) was used as a reference. The results are shown in Figure 6.

Claims

C L A I M S

1. Process for catalyzed detoxification and removal of color and undesirable compounds from contaminated liquids in the presence of an oxidant,

c h a r a c t e r i z e d by adding to the liquid an effective amount of a blood protein or a mixture of blood proteins as a multifunctional biocatalyst to obtain a liquid phase essentially free from toxic substances and color.

2. The process of claim 1, c h a r a c t e r i z e d by separating any solid phase precipitated upon addition of the blood protein to obtain a liquid phase essentially free from toxic substances and color.

3. The process of claim 1 or 2, c h a r a c t e r i z e d by using as oxidant air, oxygen, ozone, hydrogen peroxide or another chemical, biological, electrochemical or physical oxidant or an combination thereof under atmospheric or high pressure conditions or oxidative species produced by light.

4. The process of any of claims 1-3, c h a r a c t e r i z e d by further adding one or more of the following substances to enhance the process;

a) chemicals creating a twophase or multiphase system, b) oils or sufactants, c) coagulation factors, d) high reactive species stabilizers, e) oxygen vectors, f) buffers, g) catalyst activators or inhibitors, h) mediators, i) reducing agents.

5. The process of any of claims 1-4, c h a r a c t e r i z e d by adding natural animal whole blood as blood proteins.

6. The process of any of claims 1-5, cha r a c t e r i z e d by adding 1 microgram to 15 grams of the blood protein or proteins per liter liquid.

7. The process of any of claims 1-6, ch a r a c t e r i z e d by being effected in a two or multiphase system, preferably in an oil/water system.

8. The process of any of claims 1-7, c h a r a c t e r i z e d in that the biocatalyst used is a) immobilized on a solid support; b) co-immobilized with one or more other catalysts or cofactors; c) co-immobilized with one or more low molecular weight activators; f) in crosslinked form.

9. The process of any of claims 1-8, c h a r a c t e r i z e d in that the biocatalyst used has been modified by limited proteolysis or chemical or biochemical modification.

10. The process of any of claims 1-9, c h a r a c t e r i z e d by using one or more of the following methods in order to separate any solid phase obtained: a) ultrafiltration; b) sedimentation; c) flocculation;

d) centrifugation; e) filtration; f) absorbtion; g) coagulation; h) precipitation.

11. The process of claim 10, c h a r a c t e r i z e d by using as a flocculant, in order to improve the separation, inorganic salts like aluminium sulphate or anionic or cationic polymeric flocculants.

12. The process of claim 1, c h a r a c t e r i z e d by aerating the contaminated liquid in the presence of natural animal whole blood in an amount of from 1 microgram to 15 grams per liter liquid and in the presence of an oil and an oxygen vector to create a water phase/organic phase interface where the reaction proceeds, at a pH of from 1 to 14 and at a temperature of from 1 to 120ºC and within a time from 5 to 60 minutes.

13. The process of claim 1, c h a r a c t e r i z e d in that the contaminated liquid to be treated is an effluent from pulp and paper industry, mining and coal processing industry, textile, chemical, pharmaceutical or food industry.

14. The use of the process of any of claims 1-12 to bind toxic pollutants to soil and humic substances and make them less toxic.

It. The use of a blood protein or a mixture of blood proteins as a multifunctional biocatalyst for catalyzed detoxification and removal of color and undesirable compounds from contaminated liquids.