Recycling of alkali sulfate-rich wastewater by biological pretreatment with extreme halophilic organisms

Abstract

The present invention relates to an aqueous composition comprising cells of at least one halophilic microbial strain and an alkali metal sulfate in a concentration of at least 30 g / l based on the total volume of the aqueous composition. The present invention further relates to a method for treating wastewater, comprising obtaining or providing wastewater, contacting the wastewater with cells of at least one halophilic microbial strain and thereby generating an aqueous composition comprising an alkali metal sulfate in a concentration of at least 30 g / l, and incubating the aqueous composition under conditions allowing the treatment of the wastewater.

Description

Field of the Invention

[0001] The present invention relates to an aqueous composition comprising cells of at least one halophilic microbial strain and alkali sulfate in a concentration of at least 30 g / l based on the total volume of the aqueous composition. The present invention further relates to a method for treating wastewater containing alkali sulfate, comprising obtaining or providing wastewater containing alkali sulfate, contacting the wastewater with cells of at least one halophilic microbial strain, and thereby generating an aqueous composition containing alkali sulfate in a concentration of at least 30 g / l, and incubating the aqueous composition under conditions allowing the treatment of the wastewater. Background of the Invention

[0003] Solutions of sodium sulfate are produced in the reaction of many sodium compounds with sulfuric acid or with sulfur dioxide and oxygen. These solutions, as well as solutions of other alkali metal sulfates (such as potassium sulfate or lithium sulfate), must be treated to prevent water pollution.

[0004] Treatment of wastewater rich in sulfate includes physico-chemical methods (such as extraction or precipitation of sulfate) or biological treatment (such as the use of sulfate-reducing bacteria). However, these methods are complex, some require strong dilution, and use large amounts of energy and / or chemicals. The goal of conventional treatment is to convert sulfate into less ecologically harmful components and release them into the environment.

[0005] For conventional biological treatment, sulfate is degraded to form sulfide by sulfate-reducing bacteria. Organic impurities in wastewater are degraded with conventional methanogenic bacteria. However, this method produces sulfide, which shows obvious inhibition of conventional biological activity and causes unsatisfactory COD (chemical oxygen demand) removal performance. Therefore, further purification steps may be required, such as stripping, to reduce sulfide content (Yamaguchi et al., 1999).

[0006] So far, conventional biological treatments have only allowed the treatment of wastewaters with concentrations of up to 5 g of sodium sulfate per liter (see Vallero et al., 2005, Yamaguchi et al. 1999, or Saritpongteeraka, et al. 2008). In principle, higher concentrations of sodium sulfate in wastewaters inhibit biological activity. In order to allow biological treatment of sulfate-rich wastewaters, the sulfate content is currently reduced by a physico-chemical pretreatment step.

[0007] For example, US 5,346,620 discloses a method for treating wastewater rich in sodium sulfate (> 20% (w / v)) by extracting sulfate using an organic solvent. After removing the sodium sulfate, the wastewater is biologically treated by activated sludge to remove TOC (total organic carbon) and reduce organic nitrogen.

[0008] In contrast to the above-mentioned US patents, the concept of the present invention is to biologically treat sulfate-rich wastewater (> 30 g / L) without previous treatment. Since high sulfate concentrations lead to high osmotic pressures, microorganisms known to thrive in high osmotic environments are used: halophilic microorganisms. Experiments studying halophilic microorganisms are usually carried out on high concentrations of NaCl. The basic idea of ​​the present invention is to make the organisms thrive under high sodium sulfate concentrations rather than high NaCl concentrations. The response of halophilic cells to changes in cations or anions in the culture medium has been rarely studied. An exception was made by Amoozegar et al., who cultured moderately halophilic bacteria Halobionus species on a culture medium in which NaCl was replaced with KCl or NaNO3 (Amoozegar et al., 2008). Although growth was inhibited for KCl, the cells showed high cell density for NaNO3. However, for NaNO3, lipase production was highly inhibited, indicating that the exchange of anions / cations can have unpredictable consequences for enzyme production. The mechanisms and interactions of osmolytes in extreme halophiles are not yet fully understood.

[0009] The growth of halophilic microorganisms on sulfate-rich media is rarely reported in the literature. Amoozegar et al. described the growth of Halobacterium sp. strain MA-2 in media containing up to 15% (w / v) sodium sulfate (Amoozegar et al., 2003). When grown in high concentrations of sodium sulfate, Halobacterium showed significant growth and increased production of amylase in all samples. However, a later publication from the same group showed that the growth of Halobacterium MA-2 was significantly inhibited when sodium sulfate was substituted for sodium chloride (Karbalaei-Heidari et al., 2009). With 2M sodium sulfate, the formation of active product was reduced to 0 units / mL. This example shows that the response of microorganisms to high sulfate concentrations is difficult to predict and that the metabolic activity of halophilic microorganisms at high sulfate concentrations is not obvious.

[0010] The membrane electrolysis process is usually used to electrolyze solutions containing sodium chloride, but can also be used to split Na2SO4 into sulfuric acid and NaOH. Therefore, in principle, wastewater can be treated by sodium sulfate electrolysis. However, membrane electrolysis is only possible when the TOC (total organic carbon) of the solution is below a certain threshold. Higher concentrations of organic components act as confounding factors in the membrane electrolysis chamber.

[0011] Advantageously, it has been found in the studies that form the basis of the present invention that the total organic carbon content of solutions with high concentrations of sodium sulfate can be reduced by halophilic microorganisms. Therefore, halophilic microorganisms are valuable tools for treating wastewaters with high concentrations of sodium sulfate. Further, halophilic microorganisms can also be tools for treating wastewaters with high concentrations of other alkali metal sulfates, such as lithium sulfate or potassium sulfate. After the wastewater is treated by halophilic microorganisms, i.e., after the TOC content is reduced, the treated wastewater can be further subjected to electrophoresis. In the case of wastewater rich in sodium sulfate, the sodium sulfate content of the wastewater is reduced, and NaOH, sulfuric acid, oxygen and hydrogen are produced.

[0012] Based on the discovery of the present invention, it is possible to recycle wastewater streams with high alkali sulfate content. In the first step, wastewater rich in alkali sulfate, such as wastewater rich in sodium sulfate, is biologically treated for degradation of organic pollutants. As a result, total organic carbon (TOC) is reduced. In the second step of the process, alkali sulfates in the wastewater, such as Na2SO4, are electrochemically cracked, for example, into sulfuric acid and sodium hydroxide in the case of wastewater rich in sodium sulfate. Without previous biological treatment, organic components from industrial wastewater will cause membrane fouling very quickly. As a result, power consumption will increase significantly, and the migration of sodium ions will be hindered. A high-frequency cleaning system will be necessary. With the two-step process presented, effective recycling of wastewater rich in sulfate can be advantageously achieved.

[0013] The main advantage of this treatment is that chemical components are returned to the resource cycle rather than being disposed of. In the case of wastewater rich in sodium sulfate, chemicals NaOH, sulfuric acid, hydrogen and oxygen are produced from the waste stream. Compared with established disposal methods, if applied, the waste-to-value approach will be beneficial in terms of economic and ecological factors. The present invention helps to achieve a cheap, fast and effective recycling process for wastewater rich in sulfate. The extremophilic characteristics of the organisms used do not require aseptic treatment. This is an advantage in terms of cost and manageability of the process.

[0014] Brief description of the invention

[0015] The present invention relates to an aqueous composition comprising

[0016] (a) cells of at least one halophilic microbial strain, and

[0017] (b) Alkali metal sulfate

[0018] wherein the concentration of the alkali metal sulfate in the aqueous composition is at least 30 g / l based on the total volume of the aqueous composition.

[0019] In one embodiment of the present invention, the alkali metal sulfate is sodium sulfate (Na2SO4). In another embodiment of the present invention, the alkali metal sulfate is lithium sulfate (Li2SO4). In a further embodiment of the present invention, the alkali metal sulfate is potassium sulfate (K2SO4).

[0020] In one embodiment of the present invention, the concentration of alkali metal sulfate, such as sodium sulfate, in the aqueous composition is at least 50 g / l, in particular, the concentration of alkali metal sulfate in the aqueous composition is from 100 g / l to 150 g / l, based on the total volume of the aqueous composition.

[0021] In one embodiment of the present invention, the halophilic microorganism is a halophilic archaeon. In particular, the halophilic archaeon is an archaeon belonging to the family Halobacteraceae.

[0022] In a particularly preferred embodiment of the composition according to the invention, the halophilic archaea is selected from the group consisting of Haloferax mediterranei, Haloferax species D1227, Haloferax volcanii, Haloferax alexandrines, Haloferax chudinovii, Haloferax denitrificans, Haloferax elongans, Haloferax gibbonsii, Haloferax larsenii, Haloferax lucentense, Haloferax mediterranei, Haloferax mucosum, Haloferax prahovense and Haloferax sulfurifontis.

[0023] In another preferred embodiment, the halophilic archaeon is Natronobacterium gregoryi.

[0024] In another preferred embodiment of the composition of the present invention, the halophilic microorganism is a halophilic bacterium, in particular the halophilic bacterium is a bacterium belonging to the genus Halomonas, preferably Halomonasorganivorans, Halomonas species MA-C, Halomonas alimentaria, Halomonas halophila, Halomonas maura, Halomonas salina, Halomonas eurihalina.

[0025] In one embodiment of the invention, the aqueous composition further comprises at least one compound allowing the growth of the halophilic microorganisms, in particular glycerol, acetate, glucose, sucrose, lactate, malate, succinate or citrate.

[0026] In one embodiment of the present invention, the aqueous composition further comprises at least one organic contaminant, such as formate, phenol or aniline.

[0027] In one embodiment of the aqueous composition of the present invention, the aqueous composition has a TOC content of at least 50 mg / l.

[0028] In one embodiment of the aqueous composition of the present invention, the halophilic microorganism is grown in the aqueous composition.

[0029] The present invention also relates to a bioreactor comprising the aqueous composition of the present invention.

[0030] The invention further relates to a method for treating wastewater comprising

[0031] (a) obtaining or providing wastewater containing alkali metal sulphate,

[0032] (b) contacting said wastewater with cells of at least one halophilic microbial strain and thereby generating an aqueous composition according to the invention, and

[0033] (c) incubating the aqueous composition under conditions that allow for the treatment of wastewater.

[0034] In a preferred embodiment of the process according to the invention, the aqueous composition generated in step b) comprises at least one organic pollutant.

[0035] In a preferred embodiment of the process according to the invention, the treatment of the wastewater comprises reducing the total organic content of said wastewater and / or reducing the amount of at least one organic pollutant comprised by said wastewater.

[0036] In a preferred embodiment of the method of the present invention, the method further comprises the steps of separating cells from the treated wastewater to obtain a filtrate of the treated wastewater, and subjecting the obtained filtrate of the treated wastewater to alkali metal sulfate electrolysis, in particular sodium sulfate electrolysis.

[0037] Finally, the invention relates to the use of cells of at least one halophilic microbial strain for reducing the total organic carbon content of said wastewater and / or the amount of at least one organic pollutant in an aqueous composition according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0039] As mentioned above, the present invention relates to an aqueous composition comprising

[0040] (a) cells of at least one halophilic microbial strain, and

[0041] (b) Alkali metal sulfates (such as sodium sulfate (Na2SO4))

[0042] wherein the concentration of the alkali metal sulfate in the aqueous composition is at least 30 g / l.

[0043] The alkali metal sulfate is preferably sodium sulfate (Na2SO4), lithium sulfate (Li2SO4) or potassium sulfate (K2SO4).

[0044] The aqueous composition according to the invention comprises cells of at least one halophilic microbial strain.

[0045] In a preferred embodiment of the present invention, the halophilic microorganism is a halophilic archaeon (archaeon). Preferably, the halophilic archaeon is a halophilic archaeon belonging to the class Halobacterium. More preferably, the halophilic archaeon is an archaeon belonging to the order Halobacteriales. Even more preferably, the halophilic archaeon is an archaeon belonging to the family Halobacteraceae. Most preferably, the halophilic archaeon is an archaeon belonging to the genus Halobacterium.

[0046] Several species belonging to the genus Haloferax have been described in the literature, such as Halobacterium salinarum, Haloferax volcanii, Haloferax alexandrines, Haloferax chudinovii, Haloferax denitrificans, Haloferax elongans, Haloferax gibbonsii, Haloferax larsenii, Haloferax lucentense, Haloferax mediterranei, Haloferax mucosum, Haloferax prahovense and Haloferax sulfurifontis. It is therefore envisaged that the cells of the aqueous composition of the present invention belong to any of these species.

[0047] Specifically, the halophilic archaeon is Haloferax mediterranei (abbreviated herein as "HFX"). This species has been described by Rodriguez-Valera, F., Juez, G., Kushner, DJ (1983). Halobacterium mediterranei sp. nov., a new carbohydrate-utilizingextreme halophile. Syst.Appl.Microbiol. 4: 369-381 description. This document is hereby incorporated by reference in its entirety. Further, this bacterial strain has been deposited in DSM (German Collection of Microorganisms and Cell Cultures (Deutsche Sammlung von Mikroorganismen und Zellkulturen), Braunschweig, Germany) with DSM numbering 1411. How to cultivate this bacterial strain is well-known in the art. For example, suitable culture conditions can be evaluated for example from the DSMZ database of this bacterial strain.

[0048] In another preferred embodiment, the halophilic archaeon is an archaeon belonging to the genus Halobacterium. Halobacterium is a genus of the family Halobacteraceae. Preferably, the archaeon belonging to the genus Halobacterium is N. moolapensis, more preferably, the archaeon belonging to the genus Halobacterium is N. pharaonic (Kamekura M, et al. (1997). Int. J. Syst. Bacteriol. 47 (3): 853–857).

[0049] In another preferred embodiment, the halophilic archaeon is Natronobacterium gregoryi. This strain has been deposited with DSM number 3393 in the DSM (Deutsche Sammlung von Mikroorganismen und Zellkulturen, Braunschweig, Germany).

[0050] In another preferred embodiment, the halophilic microorganism is a halophilic bacterium. Preferably, the halophilic bacterium is a halophilic bacterium belonging to the class of γ-Proteobacteria. More preferably, the halophilic bacterium is a bacterium belonging to the order of Oceanospirillales. Even more preferably, the halophilic bacterium is a bacterium belonging to the family of Halomonas. Most preferably, the halophilic bacterium is a bacterium belonging to the genus Halomonas. Preferred Halomonas strains and preferred culture media for strain growth are disclosed, for example, in Mata, JA, Martínez-Cánovas, J., Quesada, E., Béjar, V., 2002. A Detailed PhenotypicCharacterisation of the Type Strains of Halomonas Species. Systematic andApplied Microbiology 25, 360–375, which is incorporated herein by reference for all its disclosures. Preferably, the halophilic bacterium is Halomonas organivorans, Halomonas species MA-C, Halomonas alimentaria, Halomonas halophila, Halomonasmaura, Halomonas salina, Halomonas eurihalina.

[0051] The most preferred Halomonas strains are Halomonas organivorans and Halomonas species MA-C. Both strains are described in the scientific literature. Strain MA-C is described, for example, by Azachi et al. (Can. J. Microbiol., vol. 41 (1995): 548-553) and Oren et al. (Biodegradation (1992), 3: 387-398) (both of which are hereby incorporated by reference in their entirety). Strain MA-C has been deposited in DSM (Deutsche Sammlung von Mikroorganismen und Zellkulturen, Braunschweig, Germany) as DSM 7328.

[0052] Preferably, the halophilic microorganism is not Halobacterium sp. strain MA-2. Thus, the composition of the present invention does not comprise cells of Halobacterium sp. strain MA-2.

[0053] The aqueous composition of the present invention is preferably a suspension of cells of a halophilic microorganism in an aqueous solution. The aqueous solution is preferably composed mainly of wastewater. As described elsewhere herein, the wastewater is preferably an organic compound. In an embodiment, the wastewater is produced by a chemical or biological production process. Preferably, the aqueous solution has an alkali metal sulfate at a concentration as described elsewhere herein.

[0054] Thus, the composition of the invention can be obtained by contacting (e.g., mixing) the cells of at least one halophilic microbial strain with a wastewater containing an alkali metal sulfate in a concentration as specified above (e.g., a concentration of at least 30 g / l). In addition, substrates, nutrients and trace elements that allow cell growth can be added to the composition. In addition, the wastewater can be treated to a specific pH as described elsewhere herein (preferably before contacting the wastewater with the cells).

[0055] Wastewaters containing alkali metal sulfates are well known in the art and can be produced, for example, by chemical or biological production processes. For example, wastewaters containing sodium sulfate are described in ULLMANN'S Encyclopedia of Industrial Chemistry, 2012, Vol. 33, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, DOI: 10.1002 / 14356007.a24-355, in particular see Table 4 on page 389. Preferably, the wastewater is selected from wastewaters from viscose-fiber spinning baths, wastewaters from sodium dichromate production, wastewaters from ascorbic acid production, wastewaters from boric acid production, wastewaters from chlorine dioxide production, wastewaters from hydroxylamine production, wastewaters from lithium carbonate production, wastewaters from sulfuric acid waste neutralization, wastewaters from the roasting and chlorination of pyrite cinders and wastewaters from the desulfurization of flue gases.

[0056] The concentration of biomass of cells of halophilic microorganisms in the composition of the present invention is preferably at least 0.1 g / l, more preferably at least 1 g / l, and most preferably at least 2 g / l. The term "biomass" as used herein means dry biomass. Thus, the term refers to the dry matter of cells of halophilic microorganisms. In one embodiment, the composition comprises about 10 6 to about 10 12 The cells contained in the composition of the present invention should be alive, i.e., living cells. Whether the cells are alive can be evaluated by well-known methods.

[0057] In a preferred embodiment of the aqueous composition of the present invention, the halophilic microorganism grows in the aqueous composition. Therefore, the halophilic microorganism should not only be alive, but it should also grow. The growth of the halophilic microorganism allows to reduce the TOC content and / or reduce the content of organic pollutants (such as phenol, formate and / or aniline) contained in the composition (as described elsewhere herein). Preferably, the halophilic microorganism grows at a rate of at least 0.005 h -1 Thus, the doubling time of the cells in the composition is 139 hours or less, for example, in the range of 5 to 139 hours. Also preferably, the growth rate μ is between 0.005 and 0.3 h -1 In the range of 0.008-0.02 h -1 Therefore, the doubling time of the cells in the composition of the present invention is preferably in the range of 2.3 to 139 hours, particularly in the range of 32.5 to 87 hours.

[0058] The composition of the present invention preferably comprises alkali metal sulfate, such as sodium sulfate, in a concentration of at least 30 g / l, more preferably in a concentration of 50 g / l, and most preferably in a concentration of 100 g / l. In the research as the basis of the present invention, a sodium sulfate concentration of 50 to 400 g / l was tested (see the Examples section). The growth of the test microorganisms was observed for a concentration of 50 to 250 g / l. For a sodium sulfate concentration of 100 to 150 g / l, the best results were obtained. Therefore, the concentration of the sodium sulfate in the composition is preferably 50 to 250 g / l, and more preferably 100 to 150 g / l. The concentrations given herein are preferably based on the cumulative volume of the aqueous composition of the present invention.

[0059] According to the art, the halophilic microorganisms require high concentrations of NaCl for growth. For example, it has been described that the strain Haloferax mediterranei tested in the examples requires a concentration of at least 60 g / l of NaCl for growth. Advantageously, it has been shown in the context of the studies underlying the present invention that Haloferax mediterranei is able to grow in an aqueous composition as defined herein, even in the absence of NaCl in the composition.

[0060] Therefore, in one embodiment of the invention, the composition does not contain NaCl, or contains NaCl at a concentration far below that required for normal growth. Preferably, the composition additionally contains less than 50 g / l of sodium chloride, more preferably less than 25 g / l of sodium chloride, even more preferably less than 10 g / l of sodium chloride.

[0061] Furthermore, it has been shown that the strains tested can grow if the composition comprises both sodium chloride and an alkali metal sulfate.Thus, sodium chloride may also be present in the composition in addition to an alkali metal sulfate, in particular in addition to sodium sulfate.

[0062] In another embodiment of the present invention, the composition may further comprise NaCl, i.e. may comprise NaCl in addition to the alkali metal sulfate (eg sodium sulfate). Preferably, the composition additionally comprises at least 50 g / l NaCl, in particular at least 100 g / l NaCl.

[0063] The pH of the composition of the aqueous composition should be adjusted for maintaining the viability of the cells of at least one halophilic microorganism. Specifically, the pH of the composition should allow the growth of the halophilic microorganism and / or reduce the TOC content or organic pollutants, as described elsewhere herein. Preferably, the pH value of the composition of the present invention is in the range of 4 to 9, more preferably in the range of 6.0 to 8.2, even more preferably in the range of 6.2 to 7.6, and most preferably in the range of 6.8 to 7.4. The optimal pH value is 7.0. In order to obtain these values, the composition can be neutralized with a suitable neutralizing agent.

[0064] Because the halophilic microorganism can grow in a composition as described above, it is a valuable tool for reducing total organic content (TOC) and therefore for treating wastewater rich in sulfate. Depending on the strain used, the amount of certain organic pollutants in the wastewater can also be reduced. For example, it was shown that HFX can reduce the degradation of formate and phenol in a composition rich in sulfate as defined herein.

[0065] Therefore, the composition of the present invention can further comprise at least one organic pollutant.Described at least one organic pollutant should be degraded by the cell of halophilic microorganism (for example by halobacteria).In a preferred embodiment, described at least one organic pollutant can be sugar, sugar alcohol, organic acid, polysaccharide, protein or aromatic organic compound (such as phenol or aniline).In an even more preferred embodiment, described organic pollutant is selected from formate, phenol and aniline.

[0066] For example, the composition preferably comprises formate in an amount of at least 10 mg / l, more preferably in an amount of at least 30 mg / l and most preferably in an amount of at least 100 mg / l (preferably based on the total volume of the composition).

[0067] For example, the composition preferably comprises aniline in an amount of at least 0.5 mg / l, more preferably in an amount of at least 2 mg / l and most preferably in an amount of at least 5 mg / l (preferably, based on the total volume of the composition).

[0068] For example, the composition preferably comprises phenol in an amount of at least 1 mg / l, more preferably in an amount of at least 5 mg / l and most preferably in an amount of at least 10 mg / l (preferably based on the total volume of the composition).

[0069] The total organic carbon content ("TOC") of the composition of the present invention is preferably at least 50 mg / l TOC, more preferably at least 75 mg / l TOC, and most preferably at least 100 mg / l TOC. TOC can be measured by methods well known in the art. In one embodiment, the TOC value is determined by high temperature catalytic oxidation. The organic carbon in the sample is oxidized using a platinum catalyst. The generated carbon dioxide gas is measured by a non-dispersive infrared (NDIR) detector.

[0070] The total organic carbon content according to the present invention does not cover cells of halophilic microorganisms. Therefore, the measurement of TOC may require the cells to be separated from the composition. For example, TOC can be measured in the clarified filtrate of the composition obtained after filtration.

[0071] The composition of the present invention preferably further comprises nutrients and trace elements, which allow the cells of halophilic microorganisms to grow in the composition. Preferably, the composition comprises at least one phosphorus source, at least one nitrogen source, at least one potassium source and at least one magnesium source as nutrients. In addition, the composition may comprise iron, copper, zinc, manganese and cobalt as trace elements.

[0072] Suitable concentrations of nutrients and trace elements can be determined by the skilled person without further effort. For example, the composition of the present invention may include one or more of the following:

[0073] (a) NH4Cl, concentration 0.5 to 3 g / l, e.g. 1.5 g / l

[0074] (b) KH2PO4, concentration 0.05 to 0.5 g / l, e.g. 0.15 g / l

[0075] (c) MgCl2* 6 H2O, concentration 0.5 to 3 g / l, e.g. 1.3 g / l

[0076] (d) CaCl2* 2 H2O, concentration 0.1 to 2 g / l, e.g. 0.55 g / l

[0077] (e) KCl, in a concentration of 0.5 to 3 g / l, e.g. 1.66 g / l

[0078] (f) MgSO4.7H2O, concentration 0.5 to 3 g / l, e.g. 1.15 g / l

[0079] (g) FeCl3, in a concentration of 0.001 to 0.1 g / l, e.g. 0.005 g / l

[0080] (h) KBr in a concentration of 0.1 to 2 g / l, e.g. 0.5 g / l

[0081] (i) MnCl2.4H2O in a concentration of 0.001 to 0.1 g / l, for example 0.003 g / l.

[0082] In a preferred embodiment of the present invention, the composition further comprises a matrix. The matrix should allow the growth of cells of the halophilic microorganism. Whether the compound allows microbial growth can be evaluated by the technician without further effort. Preferably, the matrix is ​​a carbohydrate, more preferably, the matrix is ​​glycerol, an organic acid or a sugar, more preferably, the matrix is ​​selected from glycerol, acetate, glucose, sucrose, lactate, malate, succinate and citrate. In a particularly preferred embodiment, the matrix is ​​glycerol.

[0083] In one embodiment of the composition of the invention, the composition comprises 0.5 g / l to 10 g / l, in particular 0.5 g / l to 5 g / l of the above-mentioned base, such as glycerol.

[0084] The nutrients, trace elements and, optionally, the substrate should allow the growth of the halophilic microorganisms, as specified elsewhere herein. Thus, the composition of the invention should comprise nutrients, trace elements and, optionally, the substrate in sufficient amounts (ie amounts that should allow growth).

[0085] Composition of the present invention is preferably comprised by bioreactor.Therefore, the present invention further relates to the bioreactor comprising composition of the present invention.Term " bioreactor " is well-known in the art, and preferably refers to the system in which condition is closely controlled to allow to reduce the content of at least one pollutant as mentioned herein.In one embodiment, the bioreactor is a stirred tank reactor.In a further embodiment, the bioreactor is a stripping reactor.In an even further embodiment, the bioreactor is a bubble column reactor.Preferably, the bioreactor is made of non-corrosive material, such as stainless steel, borosilicate glass or plastic (for example polysulfone (PSU), polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF)).

[0086] The definitions given above preferably apply mutatis mutandis to the following.

[0087] Therefore, the present invention further relates to a method for treating wastewater containing alkali metal sulfate, comprising

[0088] (a) obtaining or providing wastewater containing alkali metal sulphate,

[0089] (b) contacting the wastewater with cells of at least one halophilic microbial strain and thereby producing an aqueous composition of the invention, and

[0090] (c) incubating the aqueous composition under conditions that allow for the treatment of wastewater.

[0091] In a preferred embodiment, the method further comprises the step (d) of subjecting the treated (incubated) aqueous composition, ie the wastewater obtained after carrying out step (c), to electrolysis.

[0092] If the alkali metal sulfate is sodium sulfate, NaOH, sulfuric acid, oxygen and hydrogen can be produced by the electrolysis.

[0093] Therefore, the present invention further relates to a process for producing NaOH, sulfuric acid, oxygen and hydrogen, comprising

[0094] (a) obtains or provides wastewater containing sodium sulphate,

[0095] (b) contacting the wastewater with cells of at least one halophilic microbial strain and thereby producing an aqueous composition of the invention, and

[0096] (c) incubating said aqueous composition under conditions allowing for treatment of said wastewater, and

[0097] (d) subjecting the incubated aqueous composition to electrolysis, thereby producing NaOH, sulfuric acid, oxygen and hydrogen.

[0098] Before subjecting the treated wastewater to electrolysis, cells may be separated from the treated wastewater to obtain a filtrate of the treated wastewater. Thus, step d) may comprise separating cells from the treated wastewater to obtain a filtrate of the treated wastewater, and subjecting the obtained filtrate of the treated wastewater to electrolysis.

[0099] The term "treatment of wastewater" preferably refers to reducing the total organic carbon content of the wastewater and / or reducing specific organic pollutants, particularly formates, aniline and phenol. If step d) is implemented, the term preferably further includes reducing the alkali metal sulfate content, such as the sodium sulfate content of the wastewater. The term "reduction" as used herein should refer to significantly reducing (TOC content, the content of specific organic pollutants and / or the content of sodium sulfate). Preferably, the term represents reducing the TOC content, the content of specific organic pollutants and / or the content of sodium sulfate present in the composition generated in step b) by at least 30%, at least 50%, at least 70% or particularly at least 90% or at least 95%. Therefore, the content should be reduced by at least 30%, at least 50%, at least 70% or particularly at least 90% or at least 95%.

[0100] The two-step process presented here enables, in particular, the recycling of wastewaters rich in sodium sulfate. Although steps a) to c) of the process have the purpose of removing organic impurities from the wastewater, step d) recovers sulfuric acid and sodium hydroxide from the wastewater. Without previous biological treatment, organic components from industrial wastewaters will very quickly cause membrane fouling. As a result, power consumption will increase significantly and the migration of sodium ions will be hindered. A high-frequency cleaning system will be necessary. Thus, effective recycling of wastewaters rich in sulfate can be achieved.

[0101] In step b) of the aforementioned method, the wastewater is contacted with cells of at least one halophilic microbial strain. Preferably, the cells are contacted with the wastewater by mixing the cells with the wastewater, for example in a bioreactor.

[0102] By contacting the wastewater with the cells, a composition of the invention as defined above is generated. Depending on the composition of the wastewater, step b) may further comprise adding additional components to the composition. In a preferred embodiment, substrate, nutrients and / or trace elements are added to the composition.

[0103] After contacting the wastewater with the cells (and optionally adding a sufficient amount of substrate, nutrients and / or trace elements to the composition), the resulting composition is incubated to allow the treatment of the wastewater, i.e. for reducing the TOC content and / or the content of specific organic pollutants (such as formate and phenol). The incubation of the composition should be carried out under suitable conditions, i.e. under conditions that allow the reduction of the TOC content and / or the content of specific organic pollutants by the cells of the halophilic microorganisms as referred to herein. Preferably, the incubation is carried out in a bioreactor.

[0104] The term "incubating the aqueous composition under conditions that allow the treatment of the wastewater" is well known to the skilled person. The treatment of the wastewater described in step c) of the method of the invention is achieved by the activity of cells of at least one halophilic microbial strain. As the skilled person will understand, such cells require certain conditions to be active. For example, the pH value or the temperature must be within a specific range. Further, the presence of oxygen may be required. In addition, nutrients may have to be present. The establishment of suitable conditions can be implemented by the skilled person without further effort. In addition, it is usually assessed whether the cells are active.

[0105] Preferred pH values ​​and temperatures are given below.

[0106] Preferably, the incubation in step c) is carried out at a temperature of 18 to 55° C., more preferably at a temperature of 25 to 45° C., even more preferably at a temperature of 30 to 40° C., most preferably at a temperature of 35 to 40° C. The optimal temperature is 37° C.

[0107] Preferably, the incubation in step c) is carried out at a pH value in the range of 4.0 to 9.0, more preferably in the range of 6.0 to 8.2, even more preferably in the range of 6.2 to 7.6, most preferably in the range of 6.8 to 7.4. The optimum pH value is 7.2.

[0108] Depending on the pH of the wastewater to be treated, the wastewater may be neutralized. Thus, the method of the invention may further comprise the step of treating the wastewater to a pH value as indicated above, for example a pH value in the range of 4.0 to 9.0. This step is preferably performed before contacting the cells with the water. In one embodiment, the wastewater is treated to a pH value as specified herein by adding a neutralizing agent to the wastewater.

[0109] Further, the process should be carried out under aerobic conditions. Preferably, aerobic conditions are maintained by introducing air or purified oxygen into the bioreactor.

[0110] After carrying out the incubation step c), the wastewater obtained (ie the treated wastewater) can be disposed of or subjected to further steps.

[0111] In one embodiment of the method of the present invention, cells are separated from treated wastewater to obtain a filtrate of treated wastewater. Separation of cells from wastewater can be achieved by methods well known in the art. In one embodiment, cells are separated from wastewater by centrifugation. In a further embodiment, cells are separated from wastewater by decantation. In an even further embodiment, cells are separated from wastewater by sedimentation. In a particularly preferred embodiment, cells are separated from treated wastewater by filtration. Preferably, the filtration is membrane filtration.

[0112] In a preferred embodiment of the present invention, the method further comprises a step of concentrating the filtrate of the treated wastewater obtained. This step will increase the alkali metal sulfate concentration, such as sodium sulfate concentration, of the treated wastewater, i.e., sodium sulfate is concentrated upward in the treated wastewater.

[0113] The separation step and the concentration step are preferably carried out before subjecting the treated wastewater to electrolysis.

[0114] Further, the treated wastewater obtained in step c) of the method of the present invention, the filtrate of the treated wastewater obtained, or the concentrated filtrate can be subjected to a further purification step. In one embodiment of the method of the present invention, the method further comprises removing inorganic components. The inorganic components are preferably trace elements and / or salts of culture medium components. Before the treated wastewater obtained in step c), the filtrate of the treated wastewater obtained, or the concentrated filtrate is subjected to alkali metal sulfate electrolysis, such as sodium sulfate electrolysis, a further purification step should be implemented.

[0115] How to carry out the electrolysis of alkali metal sulfates is well known in the art (see, for example: ULLMANN'S Encyclopedia of Industrial Chemistry, 2012, Vol. 33, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, p. 383 -397; DOI: 10.1002 / 14356007.a24_355). The electrolysis of sodium sulfate proceeds according to the following overall reaction:

[0116] 2 Na2SO4 + 6 H2O → H2SO4 + 4 NaOH + 2H2 + O2.

[0117] In one embodiment, the electrolysis chamber is divided into two compartments separated by an ion exchange membrane. At the anode, water is oxidized into protons and oxygen. Sodium ions migrate to the cathode space through the ion exchange membrane under the action of the electric field. On the cathode side, water is electrochemically reduced to hydroxide ions and hydrogen. As a result, sulfuric acid and oxygen are formed in the anode space, and hydrogen is formed together with sodium hydroxide in the cathode space.

[0118] In another embodiment, the electrolysis chamber is divided into three compartments. In this case, the filtrate or the concentrate of the filtrate is fed to a compartment which is connected to the anode space via an anion exchange membrane on one side and to the cathode space via a cation exchange membrane on the other side. As a result, the product can be extracted with higher purity and to a higher concentration.

[0119] In another embodiment, the cathode is an oxygen depolarized cathode. In this case, the electrolysis of sodium sulfate proceeds according to the following overall reaction:

[0120] 2 Na2SO4 + 4 H2O → H2SO4 + 4 NaOH.

[0121] In the figure:

[0122] Figure 1 . Growth of HFX on medium with 150 g / L NaCl and x % Na2SO4. Optical density (OD) at 600 nm as measure of biomass concentration. Experiments were performed in triplicate (flasks 1-3). Biomass formation could be observed for all cases. Sulfate addition up to 50 g / L Na2SO4 had a positive effect on biomass growth. High reproducibility.

[0123] Figure 2: Growth of HFX on a medium with NaCl partially supplemented with Na2SO4. The optical density (OD) at 600 nm was used as a measure of biomass concentration. The experiment was performed in triplicate (flasks 1-3). Biomass formation could be observed for all cases. Sulfate addition up to 75 g / L NaCl + 91.2 g / L Na2SO4 had a positive effect on biomass growth. High reproducibility.

[0124] Figure 3 .Glycerol concentration depends on the salt concentration in the medium. 5 g / L glycerol was added at 92 h culture time. The highest degradation of glycerol was not in the reference (150 g / L NaCl + 0 g / L Na2SO4) but in the shake flasks containing sodium sulfate.

[0125] Figure 4 The formate reduction depends on the salt concentration in the medium. The differences in concentrations refer to the starting values. The reduction in formate concentration can be measured in all shake flasks.

[0126] Figure 5 .Phenol reduction depends on the salt concentration in the medium. The difference in concentrations refers to the starting value. NaCl inhibits the reduction of phenol concentration. The lower the NaCl concentration, the higher the phenol degradation.

[0127] Figure 6 .Difference in optical density between the beginning (0 h) and the end (95.5 h) of cultivation at 50-400 g / L Na2SO4 or 170 g / L NaCl (reference). The optical density (OD) at 600 nm was used as a measure of biomass concentration. ΔOD 600 is called the starting concentration to obtain relative values ​​in %. The experiment was performed in duplicate. Sodium sulfate has a positive effect on biomass growth between 50-250 g / L Na2SO4. High reproducibility.

[0128] Figure 7 Glycerol degradation between 0 and 95.5 hours depends on the salt concentration. Δc is referenced to the starting concentration to obtain the relative degradation in %. The experiments were performed in duplicate. Glycerol degradation was highest in shake flasks containing 100-150 g / L sodium sulfate.

[0129] Figure 8 Phenol degradation between 98.5 and 146 hours depended on the salt concentration. Δc was referenced to the starting concentration to obtain the relative degradation in %. The highest phenol degradation was found in the shake flasks containing 100 g / L sodium sulfate.

[0130] All references cited in the present specification are hereby incorporated by reference with respect to their entire disclosure content and the disclosure content specifically mentioned in the present specification.

[0131] The present invention will be illustrated solely by the following examples which are not to be construed in any way as limiting the scope of the present invention.

[0132] Exemplary embodiments

[0133] Example 1: Tolerance of sodium sulfate in combination with sodium chloride

[0134] Halophilus mediterranei (DSM 1411) is an extremely halophilic archaeon that requires a minimum of 140 g / L NaCl for growth. Optimal growth was reported for a concentration of 170 g / L NaCl. The experiments described in this example should answer the following questions:

[0135] 1) Can HFX tolerate high concentrations of sodium sulfate?

[0136] 2) Can HFX degrade organic components when sodium chloride in the culture medium is partially replaced by sodium sulfate?

[0137] 3) Can HFX degrade glycerol, phenol and formate components in sulfate-rich wastewater?

[0138] For part 1 of the experiment, HFX was cultivated in a culture medium containing 150 g / L sodium chloride and a sodium sulfate concentration of 0 to 100 g / L. In part 2), the sodium chloride in the culture medium was replaced with sodium sulfate. Because Na2SO4 contains two sodium molecules, every mol of NaCl is replaced by 0.5 mol Na2SO4. In parts 1) and 2), glycerol was used as a matrix. When the metabolism of the cell reduced the glycerol concentration, successful TOC reduction was shown. In part 3), the components phenol and formate were added as pulses to the shake flask. HPLC analysis should be shown in the degradation of the components over a period of 6 days.

[0139] The basal medium for all experiments contained the following composition: KCl 1.66 g / L, NH4Cl 1.5 g / L, KH2PO40.15 g / L, MgCl2.6H2O 1.3 g / L, MgSO4. 7H2O 1.1 g / L, FeCl3 0.005 g / L, CaCl2.2H2O0.55 g / L, KBr 0.5 g / L, Mn stock 3 ml and trace elements 1 ml. The pH was adjusted to 7.0. Trace elements contained Fe, Cu, Mn, Co, Zn. Sodium chloride and sodium sulfate were added to the medium as described in the experiment. Prior to cultivation, 500 mL flasks were filled to a volume of 150 mL and sterilized. Shake flasks were inoculated with 30 mL of preculture that did not contain any complex carbon or nitrogen source or sodium sulfate. The inoculum did not contain any residual carbon source. Cells were grown in a laboratory incubator (Infors, Switzerland) at 180 rpm and 37° C. Experiments 1 and 2 were performed in triplicate along with control experiments with medium only and no cells.

[0140] Can HFX tolerate high concentrations of sodium sulfate?

[0141] The results showed that HFX could grow on glycerol substrate at sodium sulfate concentrations ranging from 0 to 100 g / L (see Figure 1 Surprisingly, the OD (as a measure of biomass concentration) was highest for the experiment with 150 g / L NaCl and 50 g / L Na2SO4. This suggests that the growth of the organisms was promoted by the addition of sulfate. The results are supported by the measured values ​​of glycerol in the culture medium (see Figure 3 ). The triplicate results showed high reproducibility of this experimental part 1.

[0142] Can HFX degrade organic components when sodium chloride in the culture medium is partially replaced by sodium sulfate?

[0143] The results showed that HFX could be grown in culture medium with up to 100% replacement of sodium chloride by sodium sulfate (see Figure 2 ). Surprisingly, the OD (as a measure of biomass concentration) was the highest for the experiment with 75 g / L NaCl and 91.2 g / L Na2SO4 and was therefore higher than the reference with 150 g / L NaCl. This indicates that the growth of the organisms was promoted by the addition of sulfate. The results are supported by the measured values ​​of glycerol in the culture medium (see Figure 3 ). The triplicate results showed high reproducibility of Experimental Part 2.

[0144] The results from the glycerol measurements surprisingly showed that HFX could degrade organic components in a medium containing sodium sulfate, but not sodium chloride.

[0145] Can HFX degrade glycerol, phenol and formate components in sulfate-rich wastewater?

[0146] In experimental parts 1) and 2) the degradation of glycerol is shown. For the degradation of phenol and formate, those substances were added as a pulse to the shake flasks 92 h after inoculation. Earlier studies have shown that the removal of phenol and formate is more effective when a second substrate has been added. For this reason, the pulses were 5 g / L glycerol + 0.1 g / L phenol or 5 g / L glycerol + 1.5 g / L sodium formate. The results from experimental part 3) show that HFX can degrade both formate and phenol in sulfate-rich wastewater (see Figure 4 and 5 ). Extremely halophilic archaea thus showed simultaneous degradation of glycerol and formate or glycerol and phenol. Surprisingly, it could be observed that NaCl inhibited the degradation of phenol. Although the phenol concentration in the medium containing 150 g / L NaCl + xg / L Na2SO4 could be reduced only slightly, phenol was significantly degraded when Na2SO4 replaced NaCl. Surprisingly, the highest degradation of phenol was shown for the medium containing 182.3 g / L Na2SO4 and no NaCl (see Figure 5 ).

[0147] Example 2: Changes in Sodium Sulfate Concentration in the Culture Medium

[0148] 1) Can Halobacterium mediterraneum tolerate high concentrations of 50-400 g / L sodium sulfate without any NaCl?

[0149] 2) Can HFX degrade organic components (e.g., glycerol, phenol) in sodium sulfate-rich medium without any NaCl?

[0150] For part 1 of the experiment, sodium sulfate of different concentrations was added to the synthetic HFX medium instead of sodium chloride. Since the maximum solubility at 37°C was 480 g / L, sodium sulfate was added at a concentration of 50-400 g / L. Glycerol was used as a carbon source at a concentration of 2 g / L. When the metabolism of the cells during the 5-day culture reduced the glycerol concentration, successful TOC reduction was shown.

[0151] When glycerol was completely degraded at 96 hours, one shake flask of each duplex determination was pulsed with 0.1 g / L phenol and 2 g / L glycerol as the second substrate. The second shake flask was pulsed with 2 g / L glycerol. HPLC analysis should show degradation of the components over a 2-day period. In both parts, 1 M NaOH was used to adjust the pH in the shake flask every 24 hours.

[0152] The basal medium for all experiments contained the following composition: KCl 1.66 g / L, NH4Cl 1.5 g / L, KH2PO40.15 g / L, MgCl2.6H2O 1.3 g / L, MgSO4. 7H2O 1.1 g / L, FeCl3 0.005 g / L, CaCl2.2H2O0.55 g / L, KBr 0.5 g / L, Mn stock 3 ml and trace elements 1 ml. The pH was adjusted to 7.0. Trace elements contained Fe, Cu, Mn, Co, Zn. Sodium chloride and sodium sulfate were added to the medium as described in the experiment. Prior to cultivation, 500 mL flasks were filled to a volume of 150 mL and sterilized. Each shake flask was inoculated with 4.5 ml of preculture at an OD of 17, resulting in an initial OD of 0.5. The preculture did not contain any complex carbon or nitrogen source. The preculture contained 91 g / L sodium sulfate and 75 g / L sodium chloride, resulting in additional sodium sulfate and sodium chloride concentrations of 0.34 and 0.28 g / L in the shake flask. The inoculum did not contain any residual carbon source. The cells were grown in a laboratory incubator (Infors, Switzerland) at 180 rpm and 37°C. Experiments 1 and 2 were performed in duplicate assays together with a reference experiment with 170 g / L sodium chloride medium and a control experiment with 150 g / L sodium sulfate medium without cells.

[0153] Can Halofergi mediterranei (HFX) tolerate high concentrations of 50-400 g / L sodium sulfate without any NaCl?

[0154] The results showed that HFX could grow on glycerol substrate at sodium sulfate concentrations of 50-250 g / L without any sodium chloride (see Figure 6 The results are supported by the measured values ​​of glycerol in the culture medium (see Figure 7 ). Surprisingly, in the medium with 50-150 g / L Na2SO4, the growth of HFX was even better than in the reference with 170 g / L NaCl. As in the previous experiments, this again shows that the growth of the organism is promoted by the addition of sulfate.

[0155] HFX can degrade organic components (such as glycerol, benzene, Phenol)

[0156] The degradation of glycerol is shown in the experimental part 1). For 100 and 150 g / L Na2SO4, 100% glycerol degradation was found (see Figure 7 ).

[0157] Surprisingly, it was observed that in a medium containing 170 g / L NaCl, the phenol concentration could be reduced only slightly, whereas when NaCl was replaced by 100 g / L Na2SO4, phenol was completely degraded (see Figure). The results indicate that phenol degradation is inhibited when NaCl is present in the medium.

[0158]

Claims

1. An aqueous composition comprising at least one organic pollutant and (a) cells of at least one halophilic archaeon strain, wherein the halophilic archaeon belongs to the genus Halophora, and (b) Alkali metal sulfate wherein the aqueous composition comprises less than 50 g / l of sodium chloride and the concentration of alkali metal sulfate in the aqueous composition is at least 30 g / l based on the total volume of the aqueous composition.

2. The aqueous composition of claim 1, wherein the aqueous composition comprises the alkali metal sulfate in a concentration of at least 50 g / l, based on the total volume of the aqueous composition.

3. The aqueous composition of any one of claims 1 and 2, wherein the alkali metal sulfate is sodium sulfate (Na2SO4), lithium sulfate (Li2SO4) or potassium sulfate (K2SO4).

4. The aqueous composition of any one of claims 1 to 2, wherein the halophilic archaeon is Halophyte mediterraneum.

5. The aqueous composition of any one of claims 1 to 2, wherein the composition has a total organic carbon content (TOC) of at least 50 mg / l.

6. The aqueous composition of claim 5, wherein the organic contaminant is selected from formates, phenol or aniline.

7. The aqueous composition of any one of claims 1 to 2, wherein the halophilic archaea grows in the aqueous composition.

8. The aqueous composition of any one of claims 1 to 2, wherein the aqueous composition is wastewater comprising organic compounds, partly wastewater generated by chemical or biological production processes.

9. A bioreactor comprising the aqueous composition of any one of claims 1 to 8.

10. A method for treating wastewater containing alkali metal sulfate, comprising: (a) obtaining or providing wastewater containing alkali metal sulphate, (b) contacting the wastewater with cells of at least one halophilic archaea strain and thereby producing an aqueous composition according to any one of claims 1 to 8, and (c) incubating the aqueous composition under conditions enabling treatment of the wastewater.

11. The method of claim 10, wherein the treatment of the wastewater comprises reducing the total organic carbon content of the wastewater and / or reducing the amount of at least one organic pollutant contained in the wastewater.

12. The method of any one of claims 10 to 11, further comprising the steps of: The cells are separated from the treated wastewater to obtain a filtrate of the treated wastewater, and the obtained filtrate of the treated wastewater is subjected to alkali metal sulfate electrolysis.

13. The method of claim 12, wherein the alkali metal sulfate electrolysis comprises sodium sulfate electrolysis.

14. Use of an aqueous composition according to any one of claims 1 to 8 for reducing the amount of at least one organic pollutant and / or the total organic carbon content of wastewater.

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