Thioalkalivibrio thiocyanate halophilic alkalinity bacteria for treating sulfur-containing gas and wastewater

Abstract

The invention discloses a halophilic and basophilic thialkali thiocyanate vibrio DS21 desulfurization strain, the preservation number is 28638, the S < 2-> oxidation speed of the strain can reach 0.3-0.5 g / (L.h) under the high saline-alkaline condition (2.5 mol / L Na < + >, pH is 11.5), and the high-concentration S < 2-> (gt) is adopted; according to the present invention, with the control strategy of S < 2-> stimulation treatment, 1.5 mmol / L) stimulation treatment and oxidation under the condition that the low ORP potential is less than-400 mv, the conversion rate of the S < 2-> oxidation to generate the elemental sulfur can achieve more than 95%, the generated elemental sulfur particles are large so as to easily achieve the subsequent settling separation, and in the 2.5 mol / L Na < + > high-salt environment in the bioreactor, the S < 2-> concentration is less than 1.5 mmol / L; the thioalkalivibrio thiocyanate halophilic and alkaliphilic bacteria strain can still keep S < 2-oxidation > not lower than 0.3 g / (L.h) (about 1 cubic meter of volume per day can be oxidized to generate 7.2 kg of elemental sulfur), the oxidation speed is basically equivalent to that of a low-salt desulfurization strain used for current biological desulfurization, elemental sulfur particles generated in a bioreactor are large, the diameter of 50% of the particles is larger than 0.1 mm, and the content of sulfur in the low-salt desulfurization strain is smaller than that of sulfur in the low-salt desulfurization strain. The solid elemental sulfur is easy to settle and concentrate in a precipitator, and the concentration of the solid elemental sulfur in every 100 mL of liquid in the precipitator can reach 30-50 ml.

Description

Technical Field

[0001] The invention relates to the technical field of environmental microorganisms, in particular to a thiocyanate alkalivibrio halophilic bacterium for treating sulfur-containing gas and wastewater. Background Art

[0002] With the vigorous promotion of ecological civilization construction in my country, the proportion of clean energy in total energy consumption is increasing. Biomass biogas, as a renewable clean gas fuel, has attracted much attention. However, biomass biogas generally contains a large amount of hydrogen sulfide and other sulfur-containing compounds. If it is directly used for combustion or power generation, the corrosive hydrogen sulfide will seriously corrode the equipment. Therefore, before comprehensive utilization, the sulfur-containing compounds in biomass biogas need to be removed.

[0003] With the maturity and popularization of biological desulfurization technology, this technology has been widely used in the field of biomass biogas desulfurization. However, the salt tolerance of the desulfurization strains currently used is not high. In an environment with Na+ higher than 1.0 mol / L, the oxidation rate of S2- is significantly reduced. For this reason, it is usually necessary to continuously change the water of the liquid in the bioreactor to maintain a low Na+ environment for the entire system. However, liquid alkali is discharged during the water change process, resulting in a large amount of liquid alkali loss, which is the main reason for the high consumption of liquid alkali in the alkaline biological desulfurization process. In addition, there is a lack of sophisticated process control strategies, and the relationship between process control parameters and elemental sulfur generation rate has not been established. At present, this extensive control method causes excessive S2- (>50%) to be oxidized into H2SO4, neutralizing the alkalinity in the system, which is another major reason for the loss of liquid alkali. After calculation, the consumption cost of liquid alkali accounts for about half of the total desulfurization cost. In order to reduce the consumption of liquid alkali in alkaline biological desulfurization and further enhance its competitiveness, it is urgent to screen new halophilic desulfurization strains and establish an effective control strategy.

[0004] In response to the technical problem of low salt tolerance of biological desulfurization strains, various companies and research institutions have also disclosed some invention patents. For example: Patent application number CN111676169 A discloses a halophilic alkaliphilic micro-oxygen sulfur microspirillium, which can grow under high salt and high alkaline conditions of 0.5-4.0mol / L Na+ and pH 8.0-12.0, and the elemental sulfur production rate can reach 95%; Patent application number CN105420139A discloses a halophilic desulfurization strain NPE-1, which can grow normally in a mixed solution of 14% Na2CO3 and NaHCO3 (about 1.5-2.0mol / L Na+) and pH 10.5-11.0 environment; Patent number CN104857842 A discloses an alkaline multifunctional sulfur-alkali vibrio, which can grow normally in an environment of 0.5-4.0mol / L Na+ and pH 9.0-12.0, and the elemental sulfur production rate is greater than 90%. There are no reports of halophilic and alkaliphilic Vibrio thiocyanate strains in the published patents, no reports of detailed process control strategies, and no reports of controlling the elemental sulfur conversion rate by combining high-concentration S2- stimulation treatment and low ORP oxidation S2- strategy.

[0005] To this end, the present invention discloses for the first time a thiocyanate thioalkalivibrio halophilic bacterium for treating sulfur-containing gas and wastewater to solve the above problems. Summary of the invention

[0006] In order to overcome the above-mentioned defects of the prior art, an embodiment of the present invention provides a thiocyanate alkalivibrio halophilus for treating sulfur-containing gas and wastewater to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above-mentioned object, the present invention provides the following technical solutions: 1. A thiocyanate thioalkalivibrio halophilic bacterium for treating sulfur-containing gas and wastewater, characterized in that: the thiocyanate thioalkalivibrio halophilic bacterium for treating sulfur-containing gas and wastewater is curved in shape, 5 to 8 μm long and 0.3 to 1.0 μm wide, and is a chemoautotrophic microorganism that can use the energy obtained by oxidizing low-valent sulfur to fix CO2 and maintain its own growth;

[0008] The preservation number of the Vibrio thioalkalivibro thiocyanoxidans is: CGMCC No.28638; the preservation unit is: General Microbiology Center of China Microbiological Culture Collection Administration; the preservation address is: No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing; the taxonomic name is: Thioalkalivibro thiocyanoxidans, the survival status is: alive; the preservation time is: October 16, 2023.

[0009] A method for cultivating thiocyanate thioalkalivibrio halophilic bacteria for treating sulfur-containing gas and wastewater, characterized in that: the method comprises cultivating thiocyanate thioalkalivibrio halophilic bacteria for treating sulfur-containing gas and wastewater with 0.5-2.0 mol / L Na+ The culture medium was obtained by culturing at 37°C.

[0010] In a preferred embodiment, the culture medium further comprises 0.25 g / L NH 4 C l 、0.25g / L KNO 3 , 0.5g / LK 2 HPO 4、 0.1g / L FeSO 4 、0.1g / L MgSO 4 and 0.01 g / L MnSO 4 .

[0011] A method for controlling oxidation of sulfur-containing gases and wastewater by thiocyanate thioalkalivibrio halophilic bacteria, characterized in that: the method comprises: 2 S gas (H 2 S>2500ppm) in the scrubbing tower 1 with alkaline NaHCO 3 The solution is contacted in countercurrent to complete H 2 The S gas is eluted, and the generated rich liquid flows into the retention tank through the bottom of the scrubbing tower. The retention time in the retention tank is completed. 2- The thiocyanate thioalkalivibrio halophilic bacteria strains used to treat sulfur-containing gases and wastewater are stimulated and then flow into the bioreactor. By adjusting the frequency of the aeration fan, the amount of air entering the bioreactor is controlled in real time, and the ORP potential in the bioreactor is controlled to be below -400mv. At this time, 0.3g S can still be oxidized per liter per hour. 2- rate.

[0012] In a preferred embodiment, the high concentration S 2- When treating sulfur-containing gases and wastewater with the thiocyanate alkalivibrio halophilus strain, S 2- The concentration is greater than or equal to 1.5mmol / L, and the stimulation treatment time is greater than 5min.

[0013] In a preferred embodiment, the ORP potential control method uses an online ORP meter to monitor the ORP value in the bioreactor in real time, adjust the air exposure amount, and control the low ORP environment, whose value is lower than -400mv.

[0014] In a preferred embodiment, the high concentration S 2- For the treatment of sulfur-containing gases and wastewater, the stimulation treatment of thiocyanate alkali Vibrio halophilus and the control of ORP potential must be used in combination, and high concentration of S 2- Stimulation treatment of thiocyanate-alkalivibrio halophilus strains used to treat sulfur gases and wastewaters must precede low ORP control.

[0015] Technical effects and advantages of the present invention:

[0016] (1) Alkaline NaHCO in the bioreactor 3 The solution can be a high salt solution, Na + The concentration can be increased to 2.5 mol / L without significantly reducing the oxidation of S by Vibrio thiocyanate 2- speed, but can reduce 30% of the liquid caustic soda loss caused by wastewater discharge.

[0017] (2) After high concentration S 2- Stimulation treatment, oxidation at low ORP potential, more than 95% S in the bioreactor 2- It can be converted into elemental sulfur, which is about 50% higher than the efficiency in current bioreactors and can save 20% of liquid alkali consumption.

[0018] (3) 2.5 mol / L Na in the bioreactor + In a high-salt environment, the halophilic strain of Vibrio thiocyanate can still maintain an S of no less than 0.3 g / (L·h). 2- Oxidation (about 1 cubic meter of volume can oxidize and process 7.2 kg of elemental sulfur per day), which is basically equivalent to the oxidation rate of low-salt desulfurization bacteria currently used in biological desulfurization.

[0019] (4) The elemental sulfur particles generated in the bioreactor are relatively large, with 50% of the particles having a diameter greater than 0.1 mm. They are easily precipitated and concentrated in the precipitator. The concentration of solid elemental sulfur in every 100 mL of liquid in the precipitator can reach 30-50 ml. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The plate colony of Vibrio thiocyanate halophilus for treating sulfur-containing gas and wastewater of the present invention;

[0021] Figure 2 This is a microscope photo of the thioalkalivibrio thiocyanate used for treating sulfur-containing gas and wastewater of the present invention;

[0022] Figure 3 This is a schematic diagram of treating sulfur-containing gas and high-salt wastewater by using the thioalkalivibrio thiocyanate to treat sulfur-containing gas and wastewater;

[0023] Figure 4 The halophilic characteristics of the thioalkalivibrio thiocyanate used in the treatment of sulfur-containing gas and wastewater of the present invention;

[0024] Figure 5 The alkaliphilic characteristics of the thioalkalivibrio thiocyanate used in the treatment of sulfur-containing gas and wastewater of the present invention;

[0025] Figure 6is the 30-min elemental sulfur sedimentation ratio of the liquid in the bioreactor of the present invention;

[0026] Figure 7 The invention provides a method for treating sulfur-containing gas and wastewater by oxidizing sulfur at low ORP by using thiocyanate alkalivibrio halophilic bacteria. 2- performance.

[0027] The accompanying drawings are marked as follows: 1. washing tower; 2. retention tank; 3. bioreactor; 4. air; 5. precipitator. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Embodiment 1

[0030] Experiment on the halophilicity of Vibrio thiocyanate

[0031] Prepare 1L of the liquid culture medium shown in claim 3, adjust its pH to 8.0, take 160ml of each and add 0g, 4.68g, 9.36g, 14.04g, 18.72g and 23.40g of sodium chloride, adjust the salt concentration to 1.0mol / L, 1.5mol / L, 2.0mol / L, 2.5mol / L, 3.0mol / L, 3.5mol / L, respectively, and after dissolving, divide it into 3 conical flasks. Inoculate 18 conical flasks at 10% inoculation amount, shake and culture at 37°C, 200r / min shaking table for about 30h, and measure OD600nm at 0h, 3h, 6h, 9h, 12h, 15h, 18h, 21h and 24h, respectively, to explore the salt tolerance of Vibrio thiocyanate DS21 strain.

[0032] like Figure 4 As shown in the figure, the DS21 strain of Thioalkalivibrio thiocyanate can + Normal growth in concentration, when Na + When the concentration reaches 3.0 mol / L, the growth is slow.

[0033] Embodiment 2

[0034] Alkaliphilic experiment of Vibrio thiocyanate DS21

[0035] Prepare 2L of the liquid culture medium shown in claim 3, adjust its pH to 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5 and 12.0, a total of 9 pH gradients (adjust the pH with 10M NaOH), and after adjusting the pH, divide 160ml of the liquid culture medium into 3 conical flasks, 50ml in each flask, inoculate 5ml of the bacterial solution (10% of the inoculation amount) into 27 conical flasks respectively, and culture at 37°C, 200r / min shaking on a shaking incubator for about 30h, take samples every 3h, measure OD600nm once, and draw its 24h growth curve to observe the effect of different pH gradients on the growth of the strain.

[0036] like Figure 5 As shown, the DS21 strain of Vibrio thiocyanate can grow normally in an environment of pH 11.5, but grows slowly when the pH reaches 12.0 mol / L.

[0037] Embodiment 3

[0038] Thioalkalivibrio thiocyanate DS21 treated with H 2 Experiment on treatment of S gas and sulfur-containing high-salt wastewater

[0039] Using 0.1 mol / L Na 2 The S solution simulates the rich liquid absorbed by the scrubber, and the 5L fermenter simulates the bioreactor. The overall structure is as follows Figure 3 As shown, the liquid composition in the bioreactor is 2.5 mol / L NaHCO 3 , 0.25 g / L NH 4 C l ,0.25g / LKNO 3 , 0.5g / L K2HPO4, 0.1g / L FeSO4, 0.1g / L MgSO4, 0.01g / L MnSO4, culture conditions: 37℃, pH8.5-9.0, ORP controlled below -400mv, Na 2 The S solution was added at a constant speed via a metering pump.

[0040] After the whole system is stable, measure S 2- , S 2 O 3 2- 、SO 4 2- Content, calculate S 2- The oxidation rate and elemental sulfur conversion rate are shown in the following table. Figure 7As shown, as the controlled ORP potential decreases, the growth conversion rate of elemental sulfur rapidly increases from 75.1% to 95.8%. By measuring the alkalinity of the overall reaction system before and after the reaction, it is calculated that approximately 0.1 mol NaOH is consumed for each oxidation of 1 mol S2- (excluding the NaOH consumed by external discharge).

[0041] Finally, a few points should be explained: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, which may refer to mechanical connection or electrical connection, or internal communication between two components, or direct connection. "upper", "lower", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may change;

[0042] Secondly: In the drawings of the embodiments disclosed in the present invention, only the structures involved in the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other; Finally: The above are only preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A thiocyanate thioalkalivibrio halophilic bacterium for treating sulfur-containing gases and wastewater, characterized in that: The thiocyanate thioalkalivibrio halophilic bacteria for treating sulfur-containing gas and wastewater has a curved shape, is 5 to 8 μm long and 0.3 to 1.0 μm wide, has a preservation number of 28638, is a chemoautotrophic microorganism, and can use the energy obtained by oxidizing low-valent sulfur to fix CO2 and maintain its own growth.

2. A method for cultivating Vibrio thiocyanate halophilic bacteria for treating sulfur-containing gases and wastewater, characterized in that: The method comprises treating sulfur-containing gas and wastewater with thiocyanate thioalkalivibrio halophilic alkali bacteria through a 0.5-2.0 mol / L Na + The culture medium was obtained by culturing at 37°C.

3. The method according to claim 2, characterized in that The culture medium also includes 0.25 g / L NH4C l 、0.25g / LKNO3、0.5g / L K2HPO 4、 0.1g / L FeSO4, 0.1g / L MgSO4 and 0.01g / L MnSO4.

4. A method for controlling oxidation of thiocyanate-alkalivibrio halophilus for treating sulfur-containing gases and wastewater, characterized in that: The method comprises the following steps: the H2S-containing gas (H2S>2500ppm) before purification is contacted with an alkaline NaHCO3 solution in a washing tower 1 in countercurrent flow to complete the elution of the H2S gas; the generated rich liquid flows into a retention tank 2 through the bottom of the washing tower 1, and stays in the retention tank 2 for a certain period of time to complete the high-concentration S 2- The thiocyanate thioalkalivibrio halophilic bacteria strains used to treat sulfur-containing gases and wastewater are stimulated and treated, and then flow into the bioreactor 3. By adjusting the frequency of the aeration fan, the amount of air 4 introduced into the bioreactor 3 is controlled in real time, and the ORP potential in the bioreactor 3 is controlled to be below -400mv. At this time, 0.3g S can still be oxidized per liter per hour. 2- rate.

5. The method according to claim 4, characterized in that The high concentration S 2- When treating sulfur-containing gases and wastewater with the thiocyanate alkalivibrio halophilus strain, S 2- The concentration is greater than or equal to 1.5mmol / L, and the stimulation treatment time is greater than 5min.

6. The method according to claim 4, characterized in that The ORP potential control method uses an online ORP meter to monitor the ORP value in the bioreactor 3 in real time, adjust the air 4 exposure amount, and control the low ORP environment, whose value is lower than -400mv.

7. The method according to claim 2, characterized in that: The high concentration S 2- For the treatment of sulfur-containing gases and wastewater, the stimulation treatment of thiocyanate alkali Vibrio halophilus and the control of ORP potential must be used in combination, and high concentration of S 2- Stimulation treatment of thiocyanate-alkalivibrio halophilus strains used to treat sulfur gases and wastewaters must precede low ORP control.

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