Recycling of alkali sulfate rich waste water by biological pre-treatment with an extreme halophilic organism

Abstract

The present invention relates to an aqueous composition comprising cells of at least one strain of a halophilic microorganism, 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 a waste water, comprising obtaining or providing a waste water, contacting said waste water with cells of at least one strain of a halophilic microorganism, and thereby generating an aqueous composition comprising alkali sulfate in a concentration of at least 30 g/l, and incubating said aqueous composition under conditions which allow for the treatment of the waste water.

Claims

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

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

3. The aqueous composition of claim 1, wherein said alkali sulfate is sodium sulfate (Na.sub.2SO.sub.4), lithium sulfate (LiSO.sub.4), or potassium sulfate (K.sub.2SO.sub.4).

4. The aqueous composition of claim 1, wherein the halophilic archaeon belongs to the family of the Halobacteriaceae.

5. The method of claim 1, wherein the halophilic archaeon is Haloferax mediterranei.

6. The aqueous composition of claim 1, wherein the aqueous composition further comprises at least one organic compound as an organic contaminant.

7. The aqueous composition of claim 1, wherein the composition has a total organic carbon content (TOC) of at least 50 mg/l.

8. The aqueous composition of claim 6, wherein the organic contaminant is selected from formate, phenol, and aniline.

9. The aqueous composition of claim 1, wherein the halophilic archaeon is growing in the aqueous composition.

10. The aqueous composition of claim 1, wherein the aqueous composition is a waste water comprising organic compounds resulting from chemical or biological production processes.

11. A bioreactor comprising the aqueous composition of claim 1.

12. A method for treating a waste water comprising alkali sulfate, comprising (a) obtaining or providing a waste water comprising alkali sulfate, having a concentration of alkali sulfate in the aqueous composition is at least 30 g/l based on the total volume of the of the aqueous composition, (b) contacting the waste water with cells of at least one strain of a halophilic archaeon microorganism, resulting in the aqueous composition according to claim 1, and (c) incubating said aqueous composition under conditions which that allow for the treatment of the waste water.

13. The method of claim 12, wherein the treatment of the waste water comprises the reduction of the total organic content of said waste water and/or the reduction of the amount of at least one organic contaminant comprised by said waste water.

14. The method of claim 12, further comprising the steps of separating the cells from the treated waste water to obtain a filtrate of treated waste water and subjecting the obtained filtrate of treated waste water to alkali sulfate electrolysis.

15. A method comprising providing cells of at least one strain of a halophilic archaeon and reducing an amount of total organic carbon content in a waste water and/or an amount of at least one organic contaminant in the aqueous composition according to claim 1.

Description

(1) In the figures:

(2) FIG. 1. Growth of HFX on Medium with 150 g/L NaCl and x % Na.sub.2SO.sub.4. Optical Density (OD) at 600 nm as a measure for the biomass concentration. The experiments were performed in triplicates (flask 1-3). Formation of biomass could be observed for all cases. Addition of sulfate had a positive influence on biomass growth up to 50 g/L Na.sub.2SO.sub.4. Reproducibility was high.

(3) FIG. 2: Growth of HFX on Medium with NaCl partially supplemented by Na.sub.2SO.sub.4. Optical Density (OD) at 600 nm as a measure for the biomass concentration. The experiments were performed in triplicates (flask 1-3). Formation of biomass could be observed for all cases. Addition of sulfate had a positive influence on biomass growth up to 75 g/L NaCl+91.2 g/L Na.sub.2SO.sub.4. Reproducibility was high.

(4) FIG. 3. Glycerol concentration in dependence of salt concentration in the medium. Addition of 5 g/L glycerol at 92 h culture time. Highest degradation of glycerol not in reference (150 g/L NaCl+0 g/L Na.sub.2SO.sub.4), but in shake flask containing sodium sulfate.

(5) FIG. 4. Formate reduction in dependence of salt concentration in the medium. Difference in concentration was referred to the start value. Decrease of formate concentration could be measured in all shake flasks.

(6) FIG. 5. Phenol reduction in dependence of salt concentration in the medium. Difference in concentrations was referred to the start value. Decrease of phenol concentration was repressed by NaCl. The lower the NaCl concentration was the higher was the phenol degradation.

(7) FIG. 6. Optical density difference between start (0 hours) and end of cultivation (95.5 hours) at 50-400 g/L Na.sub.2SO.sub.4 or 170 g/L NaCl (Reference). Optical Density (OD) at 600 nm is used as measure for the biomass concentration. ΔOD.sub.600 was referred to start concentration to obtain relative values in %. The experiments were performed in double determination. Sodium sulfate had a positive influence on biomass growth between 50-250 g/L Na.sub.2SO.sub.4. Reproducibility was high.

(8) FIG. 7. Glycerol degradation between 0 and 95.5 hours in dependence of salt concentration. Ac was referred to start concentration to obtain relative degradation in %. The experiments were performed in double determination. Highest degradation of glycerol in shake flask containing 100-150 g/L sodium sulfate.

(9) FIG. 8. Phenol degradation in between 98.5 and 146 hours in dependence of salt concentration. Δc was referred to start concentration to obtain relative degradation in %. Highest degradation of phenol was found in shake flask containing 100 g/L sodium sulfate.

(10) All references cited in this specification are herewith incorporated by reference with respect to their entire disclosure content and the disclosure content specifically mentioned in this specification.

(11) The invention will be merely illustrated by the following Examples. The said Examples shall, whatsoever, not be construed in a manner limiting the scope of the invention.

EXEMPLARY EMBODIMENTS

Example 1: Toleration of Sodium Sulfate in Combination with Sodium Chloride

(12) Haloferax mediterranei (DSM 1411) is an extreme halophilic archaeon which requires a minimum of 140 g/L NaCl for growth. Optimal growth is reported for concentrations of 170 g/L NaCl. The experiments described in this example should answer the following questions: 1) Can HFX tolerate high concentrations of sodium sulfate? 2) Can HFX degrade organic components when sodium chloride in the medium is partly replaced by sodium sulfate? 3) Can HFX degrade the components glycerol, phenol and formate in sulfate rich waste water?

(13) For part 1) of the experiment HFX was cultivated in medium containing 150 g/L sodium chloride and sodium sulfate in concentrations of 0 to 100 g/L. In part 2) the sodium chloride in the medium was replaced by sodium sulfate. Because Na.sub.2SO.sub.4 contains two sodium molecules, each mol of NaCl was replaced by 0.5 mol Na.sub.2SO.sub.4. In part 1) and 2) glycerol is used as substrate. A successful TOC reduction is shown, when glycerol concentration is decreased by the cell's metabolism. In part 3) the components phenol and formate were added to the shake flasks as pulses. HPLC analysis should show the degradation of the components over a period of 6 days.

(14) The basal medium for all experiments contained the following components: KCl 1.66 g/L, NH.sub.4Cl 1.5 g/L, KH.sub.2PO.sub.4 0.15 g/L, MgCl.sub.2.6H.sub.2O 1.3 g/L, MgSO.sub.4. 7H.sub.2O 1.1 g/L, FeCl.sub.3 0.005 g/L, CaCl.sub.2.2H.sub.2O 0.55 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 containing Fe, Cu, Mn, Co, Zn. Sodium chloride and sodium sulfate were added to the medium according to the description of the experiment. The 500 mL flasks were filled with a volume of 150 mL and sterilized prior to cultivation. Shake-flasks were inoculated with 30 mL preculture that did not contain any complex carbon or nitrogen source or sodium sulfate. The inoculum was free of any residual carbon source. Cells were grown in laboratory incubator (Infors, Switzerland) with 180 rpm and 37° C. Experiments 1 and 2 were done in triplicates together with a control experiment with only medium and no cells.

(15) Can HFX Tolerate High Concentrations of Sodium Sulfate?

(16) Results show that HFX can grow on the substrate glycerol at sodium sulfate concentrations of 0 to 100 g/L (see FIG. 1). Surprisingly the OD, as measure for the biomass concentration, is highest for the experiment with 150 g/L NaCl and 50 g/L Na.sub.2SO.sub.4. This indicates that growth of the organism is promoted by addition of sulfate. The results are supported by the measurement of glycerol in the medium (see FIG. 3). The results of the triplicates showed high reproducibility for this experiment part 1.

(17) Can HFX Degrade Organic Components when Sodium Chloride in the Medium is Partly Replaced by Sodium Sulfate?

(18) Results show that HFX can grow in medium where sodium chloride is replaced by sodium sulfate up to 100% (see FIG. 2). Surprisingly the OD, as measure for the biomass concentration, is highest for the experiment with 75 g/L NaCl and 91.2 g/L Na.sub.2SO.sub.4 and therefore higher than the reference with 150 g/L NaCl. This indicates that growth of the organism is promoted by addition of sulfate. The results are supported by the measurement of glycerol in the medium (see FIG. 3). The results of the triplicates showed high reproducibility for experiment part 2.

(19) Results from the glycerol measurements surprisingly show that HFX can degrade organic components in medium that contained sodium sulfate but no sodium chloride.

(20) Can HFX Degrade the Components Glycerol Phenol and Formate in Sulfate Rich Waste Water?

(21) Degradation of glycerol was shown in experiment part 1) and 2). For the degradation of phenol and formate, those substances were added to the shake flasks as a pulse after 92 h of inoculation. Earlier studies showed that the removal of phenol and formate was more effective when a second substrate had been added. For this reason the pulse were 5 g/L glycerol+0.1 g/L phenol or 5 g/L glycerol+1.5 g/L sodium formate. Results from experiment part 3) showed that both formate and phenol could be degraded in sulfate rich waste water by HFX (see FIGS. 4 and 5). The extreme halophilic archaeon thereby showed simultaneous degradation of glycerol and formate or glycerol and phenol. Surprisingly it could be observed that degradation of phenol is suppressed by NaCl. While phenol concentration could be reduced only little in medium containing 150 g/L NaCl+x g/L Na.sub.2SO.sub.4, the phenol was degraded significantly when NaCl was replaced by Na.sub.2SO.sub.4. Highest degradation of phenol surprisingly showed for medium with 182.3 g/L Na.sub.2SO.sub.4 and no NaCl (see FIG. 5).

Example 2: Variation of Sodium Sulfate Concentration in the Medium

(22) 1) Can Haloferax mediterranei tolerate high concentrations of 50-400 g/L sodium sulfate without any NaCl? 2) Can HFX degrade organic components (e.g. glycerol, phenol) in sodium sulfate rich medium without any NaCl?

(23) For part 1) of the experiment, instead of sodium chloride different concentrations of sodium sulfate were added to the synthetic HFX medium. Due to the maximum solubility of 480 g/L at 37° C., sodium sulfate was added in concentrations of 50-400 g/L. Glycerol was used as carbon source in a concentration of 2 g/L. A successful TOC reduction is shown, when the glycerol concentration is decreased by the cell's metabolism during 5 days of cultivation.

(24) When the glycerol was fully degraded at 96 hours, one shake flask of every double determination was pulsed with 0.1 g/L phenol and 2 g/L glycerol as second substrate. The second shake flask was pulsed with 2 g/L glycerol. The HPLC analysis should show the degradation of the components over a period of 2 days. In both parts the pH in the shake flasks was adjusted every 24 hours using 1 M NaOH.

(25) The basal medium for all experiments contained the following components: KCl 1.66 g/L, NH.sub.4Cl 1.5 g/L, KH.sub.2PO.sub.4 0.15 g/L, MgCl2.6H.sub.2O 1.3 g/L, MgSO.sub.4. 7H.sub.2O 1.1 g/L, FeCl.sub.3 0.005 g/L, CaCl.sub.2.2H.sub.2O 0.55 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 containing Fe, Cu, Mn, Co, Zn. Sodium chloride and sodium sulfate were added to the medium according to the description of the experiment. The 500 mL flasks were filled with a volume of 150 mL and sterilized prior to cultivation. Each shake-flask was inoculated with 4.5 ml preculture with 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 an additional sodium sulfate and sodium chloride concentration of 0.34 and 0.28 g/L in the shake flasks. The inoculum was free of any residual carbon source. Cells were grown in laboratory incubator (Infors, Switzerland) with 180 rpm and 37° C. Experiments 1 and 2 were done in double determination 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.

(26) Can Haloferax mediterrnei (HFX) tolerate high concentrations of 50-400 g/L sodium sulfate without any NaCl?

(27) The results show, that HFX can grow on the substrate glycerol at sodium sulfate concentrations of 50-250 g/L without any sodium chloride (see FIG. 6). The results are supported by the measurement of glycerol in the medium (see FIG. 7). Surprisingly HFX grew even better in medium with 50-150 g/L Na.sub.2SO.sub.4, than in the reference with 170 g/L NaCl. As in the previous experiment, this indicates again, that growth of the organism is promoted by addition of sulfate.

(28) Can HFX Degrade Organic Components (e.g. Glycerol, Phenol) in Sodium Sulfate Rich Medium without any NaCl?

(29) Degradation of glycerol was shown in experiment part 1). 100% glycerol degradation was found for 100 and 150 g/L Na.sub.2SO.sub.4 (see FIG. 7).

(30) Surprisingly it could be observed that the phenol concentration could be reduced only a little in medium containing 170 g/L NaCl, while phenol was fully degraded when NaCl was replaced by 100 g/L Na.sub.2SO.sub.4 (see figure). The results indicate that phenol degradation is suppressed when NaCl is contained in the medium.

CITED LITERATURE

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