DE102008055079A1 - Removing substances e.g. selenium and/or tellurium from liquid/gaseous medium, using microorganisms, comprises culturing and enriching microorganism in medium containing substance and nutrients, and separating microorganism from the medium - Google Patents

Abstract

Removing substances from liquid or gaseous medium, using microorganisms, comprises culturing and enriching the microorganism in a medium containing the substance and nutrients, and finally separating the microorganism from the medium after culturing time, where: the microorganism contains the substance in it; and the selenide-ion, hydrogen selenide, telluride ion and/or hydrogen telluride are enriched using sulfide oxidizing microorganisms and separated from the medium.

Description

introduction

The The invention relates to a method for removing a substance a liquid or gaseous medium with the help of microorganisms, the microorganisms in which the substance and nutrient-containing medium is cultured and enriched and finally after a period of cultivation separated from the medium, wherein they contain the substance in itself.

State of the art

As is "bioleaching" a microbial ore leaching known in which heavy metals from their Ores by conversion of insoluble ore minerals to water-soluble salts are obtained by microorganisms. It is therefore a branch of biohydrometallurgy, d. H. a metal extraction by biological-wet-chemical processes, mainly copper, zinc, cobalt, nickel, gold and uranium are extracted. The most significant representatives more laxative Microorganisms are bacteria and archaea, the sulfide and elemental sulfur oxidize to sulfate. The oxidation of divalent was also proved to trivalent iron. Among the bacteria, it is mainly the so-called Sulfur bacteria Acidithiobacillus ferrooxidans and Acidithiobacillus Thiooxidans, which can be oxidized sulfide and sulfur compounds. With proper operation, bioleaching processes become apparent due to their low energy consumption and their environmental friendliness because there is no significant emission of pollutants.

task

Of the Invention is based on the object, a method for removal or to suggest enrichment of a substance with the help of microorganisms, which is also applicable to substances that have not previously been Procedures were removed or enriched.

solution

outgoing from a method of the type described above is the basis This object is achieved in that selenide ions and / or Selenium and / or telluride ions and / or tellurium hydrogen Enriched with the help of sulfide oxidizing microorganisms and be removed from the medium.

Surprisingly, it has been found that the microorganisms known per se from various bioleaching processes, ie in particular sulfur bacteria with oxidative sulfur metabolism, not only oxidize sulfide ions but also selenide ions and / or selenium and / or telluride ions and / or tellurium hydrogen and intracellular (periplasmic) can store in the elementary form. Using so-called XANES spectroscopy it could be proven that elemental selenium or tellurium are present in the sulfur bacteria in elemental form. The bacteria in question perform a kind of detoxification reaction and thus remove the selenide or telluride ions from the surrounding medium. The elemental selenium or tellurium is stored in the cells of the bacteria in chain form. Externally, it is surrounded by a protein shell and forms the shape of a sphere. Although it is known ( Applied and Environmental Microbiology, Jan. 2004, pp. 52-60 "Structural and Spectral features of Selenium Nanospheres Produced by Se-respiring Bacteria" by Ronald S. Oremland et al. ), that certain anaerobic bacteria (Sulfurospirillum barnesii, Bacillus selenitireducens, Selenihalanaerobacter shriftii) in terms of selenium, selenite and selenate can reduce to elemental selenium. The inventively discovered oxidative selenium metabolic processes of sulfur bacteria were previously unknown. The same applies to tellurites and tellurates in conjunction with the reducing bacterial strains Bacillus selenitireducens and Sulfurospirillum barnesii ( Applied and Environmental Microbiology, Apr. 2007, pp. 2135-2143 "Formation of Tellurium Nanocrystals During Anaerobic Growth of Bacteria That Use Te Oxyanions as Respiratory Electron Acceptors" by Shaun M. Baesman et al ).

selenium Although as an essential trace element is part of the 21st amino acid, Selenocysteine, as well as contained in bacteria archaea and eukaryotes. Selenium compounds are therefore offered as a dietary supplement and processed into feed and fertilizer additives. In the art, in the glass industry, in semiconductor manufacturing, as a latex additive, in toner and pigment production, as an alloying additive and used in so-called CIS solar cells.

Also if selenium deficiency diseases occur in some parts of the world, On the other hand, there is even the suspicion that certain carcinomas or type 2 diabetes favored by excessive selenium intake become. Selenium and selenium compounds are therefore considered toxic and A corresponding hazardous substance labeling is required.

Tellurium is a rare chemical element whose frequency is approximately that of gold, with which it also enters into various compounds. Tellurium, together with selenium, is obtained industrially exclusively from by-products of large-scale electrolytic copper and nickel production. In the resulting anode slurries contain water-insoluble noble metal tellurides and selenides. In the art, it is used in the metal industry as an alloying additive as well as in the preparation of compound semiconductors. In contrast to selenium, tellurium is considered to be a non-essential trace element, ie a tellurium-based biological function is suspected but has not yet been detected. However, tellurium is a poisonous element for the human organism and must therefore be marked with the corresponding hazard symbol.

With the process of the invention has now been a very useful and efficient method discovered to Loads of liquid or gaseous media with selenide ions and / or selenium and / or telluride ions and / or telluric hydrogen with the help of sulfur bacteria to remove and to gain elemental selenium and / or tellurium in this way. If Strain of a medium with both selenium and tellurium These can be removed at the same time and selenium and tellurium are obtained in elemental form. In particular, come Bacteria of the families Chromaticeae, Beggiatoaceae, Achromaticeae, Sulfolobus, Halorhodospiraceae, Ectothiorhodospiraceae, Chlorobiaceae, Pseudomonaceae, Thiobacillaceae in question.

Furthermore, it has been found that the microorganisms used for carrying out the method according to the invention may preferably be strains from the group of the phototrophic sulfur bacteria, in particular Allochromatium vinosum, in particular Allochromatium vinosum DSMZ 180 ^T , wherein the cultivation takes place at a pH of between 6 and 8, preferably about 7, and in the absence of oxygen.

alternative It is also possible, as microorganisms strains to use from the group of chemotrophic sulfur bacteria, in particular Acidithiobacillus ferrooxidans, in particular Ferrobacillus acid dioxide DSMZ 584/585, wherein the cultivation at a pH between 2 and 7 and in the presence of oxygen.

To Expiration of the selected cultivation period can the microorganisms in a simple manner by centrifugation removed from the medium. After that they can, for example be destroyed by ultrasonic treatment, thereby Selenium and / or Tellurkugeln be free, which in turn by a Centrifugation be sedimented, with any Enveloped proteins removed by enzymatic treatment can be.

If phototrophic sulfur bacteria can be used, the irradiation a reactor in which the medium to be treated is contained, carried out with the growth of microorganism-promoting light become. In this way, regardless of the outer Environmental conditions a reproducible and easily controllable procedure be achieved. It may be useful to the artificial irradiation to terminate and any others present, d. H. in particular natural (solar) radiation from the microorganisms at some point in the process keep. In this way it can be prevented that the intracellular formed selenium or tellurium balls to selenate or tellurate be oxidized.

alternative However, this can also be aware of the cultivation of microorganisms continue until elemental selenium or tellurium of the microorganisms is oxidized to selenate or tellurate, including in particular microorganisms of the strains Acidithiobacillus ferrooxidans be used.

at It has been found that the cultivation of microorganisms preferably at temperatures between about 15 ° C and 40 ° C, preferably between about 20 ° C and 35 ° C, should be done, as here is a particularly large Activity is observed.

by virtue of the use of so-called sulfur bacteria it is possible simultaneously with the removal of selenide ions and / or hydrogen selenide and / or telluride ions and / or tellurium hydrogen also sulfide ions and / or to remove hydrogen sulphide. In the bacteria will then at the same time also elemental sulfur accumulated.

in principle the process of the invention can be used either as continuous flow process or in batch mode become. When using pure cultures of the bacterial strains mentioned become well reproducible results with the invention Procedure achieved.

embodiment

The inventive method is described below an embodiment explained in more detail. Task is the removal of selenide and / or telluride ions and / or selenium and / or tellurium hydrogen from a polluted aqueous Solution, for example, from an industrial wastewater treatment plant comes.

The substances to be removed are in the aqueous solution to be treated in a concentration of 10 g Na ₂ Se or Na ₂ Te ad 100 ml distilled water. contain. The aqueous solution is mixed with phototrophic sulfur bacteria of the strain Allochromatium vinosum DSMZ 1807. The bacteria are in prior to adding the aqueous solution in the sta tionary phase. As a nutrient medium, RCV medium is used for good bacterial growth (photoorganoheterotrophic growth) ( Weaver et al., 1975 Weaver, PF, Wall, JD & Gest, H. (1975). Characterization of Rhodopseudomonas capsulata. Arch Microbiol 105, 207-216 ).

To Start of cultivation on 10 bacterial culture 10 ml solution (see above) (corresponds to 1 g of selenide or telluride). The glass reactors will be with light from several household light bulbs (each 60 watts), with the tungsten filaments typical broad emission spectrum, irradiated and by means of a Stirred stirred, so that the entire reactor contents temporarily circulated near the glass mantle.

The Temperature of the aqueous medium during the cultivation period is about 30 ° C and the pH is about 6.8

To a treatment duration of approx. 2 to 5 h, the lighting of the Shut off the glass reactor and the pH to 8, to a further oxidation to prevent selenate or tellurate. With the help of a centrifuge The bacteria are removed from the aqueous solution deposited. Subsequently, the bacteria are sonicated treated so that their cell membranes, eg. T also ball enveloping membranes, be destroyed, creating elemental selenium and / or tellurium get free. These are sedimented by further centrifugation.

Provided a sufficient amount of time is available to the bacteria (depending on temperature, light conditions, Nutrient media, etc.), finds a complete implementation all selenide or telluride to elemental selenium or tellurium instead. To poison and die off the bacteria The concentration of selenide or telluride ions should be avoided in the solution to be treated below about 1 to 2 g / l.

Next the application of the method described above to wastewater treatment wastewater leaves the method also apply to loaded gas mixtures, such as For example, in oil processing or in the Natural gas production available.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - Applied and Environmental Microbiology, Jan. 2004, pp. 52-60 "Structural and Spectral features of Selenium Nanospheres Produced by Se-respiring Bacteria" by Ronald S. Oremland et al. [0005]
• - Applied and Environmental Microbiology, Apr. 2007, p. 2135-2143 "Formation of Tellurium Nanocrystals During Anaerobic Growth of Bacteria That Use Te Oxyanions As Respiratory Electron Acceptors" by Shaun M. Baesman et al [0005]
• Weaver et al., 1975 Weaver, PF, Wall, JD & Gest, H. (1975). Characterization of Rhodopseudomonas capsulata. Arch Microbiol 105, 207-216 [0019]

Claims (11)

Method for removing a substance from a liquid or gaseous medium with the aid of microorganisms, wherein the microorganisms are cultured and enriched in the medium containing the substance and nutrients and are finally separated from the medium after a cultivation period, wherein they contain the substance, characterized in that selenide ions and / or selenium and / or telluride ions and / or tellurium hydrogen are enriched by means of sulfide oxidizing microorganisms and removed from the medium. A method according to claim 1, characterized in that the microorganisms are strains from the group of phototrophic sulfur bacteria, in particular Allochromatium vinosum, in particular Allochromatium vinosum DSMZ 180 ^T , wherein the cultivation at a pH of between 6 and 8, preferably about 7 to 7, 5, and in the absence of oxygen. Method according to claim 1, characterized in that that the microorganisms strains from the group of chemotrophic Sulfur bacteria, in particular Acidithiobacillus ferrooxidans, in particular Ferrobacillus acidithiooxidans DSMZ 584/585, wherein culturing at a pH between 2 and 7 and in the presence of oxygen. Method according to one of claims 1 to 3, characterized in that the microorganisms from the medium be removed by centrifugation. Method according to one of claims 1 to 4, characterized in that the microorganisms, preferably after their removal from the medium, by means of ultrasound treatment are destroyed, thereby releasing selenium and / or tellurium balls which are sedimented by centrifugation, possibly Enveloped proteins removed by enzymatic treatment become. Method according to one of claims 2 to 5, characterized in that in the case of use phototrophic Sulfur bacteria containing an irradiation of the medium to be treated Reactor with the growth of microorganisms promoting Light is emitted and the irradiation stops and eventually existing other radiation is kept away from the microorganisms, if intracellular selenium and / or tellurium balls have been formed are. Method according to one of claims 1 to 6, characterized in that the cultivation of microorganisms is continued until elemental selenium from the microorganisms is oxidized to selenate, including in particular microorganisms of Strains Acidithiobacillus ferrooxidans be used. Method according to one of claims 1 to 6, characterized in that the cultivation of microorganisms at temperatures between about 15 ° C and 40 ° C, preferably between about 20 ° C and 35 ° C, he follows. Method according to one of claims 1 to 7, characterized in that simultaneously with the distance of selenide ions and / or selenium and / or telluride ions and / or tellurium hydrogen also sulfide ions and / or hydrogen sulfide Will get removed. Method according to one of claims 1 to 9, characterized in that a starting concentration of the selenide ions or telluride ions in the liquid medium at the beginning the cultivation is less than 2 g / l, preferably less than 1.5 g / l, more preferably less than 1.0 g / l. Method according to one of claims 1 to 9, characterized in that the method as continuous Flow process or runs in batch mode.