CN106635210A - Method for removing hydrogen sulfide in biogas by using Acidithiobacillus caldus - Google Patents

Abstract

The invention discloses a method for removing hydrogen sulfide in biogas by mesophilic acidophilic thiobacillus. hydrogen sulfide, the fermentation temperature is 40~45℃. The mesophilic acidophilic Thiobacillus is a strain with a strain number of 1.7296 preserved in the China Microorganism Culture Collection Center. The number of viable cells in the fermentation broth of mesophilic acidophilus thiobacterium was 2.0×10 ⁶ cells/mL~10.0×10 ⁶ cells/mL. The method has the advantages of convenient operation, simple process flow, improved resource utilization value, cost saving, and improved desulfurization efficiency, and can stably and efficiently remove hydrogen sulfide in biogas, which will help improve the utilization level of biogas and break through the difficult problem of biogas desulfurization.

Description

A method for removing hydrogen sulfide in biogas by mesophilic acidophilic thiobacillus

technical field

The invention belongs to the technical field of bioenergy, and in particular relates to a method for removing hydrogen sulfide in biogas by mesophilic acidophilus thiobacterium.

Background technique

With the rapid development of the economy, the demand for energy around the world is increasing day by day. In the energy structure, fossil energy such as oil and coal still occupies a dominant position. If human beings rely too much on these traditional fossil energy, their non-renewability will definitely cause an energy crisis. As a new green energy, biogas has gradually attracted people's attention. Biogas is a mixed gas, which generally contains 60%~70% _CH4 , 30%~40 _{% CO2} , and a small amount of H2S, water vapor, _NH3 , etc. Among them, hydrogen sulfide is harmful to personal safety, environment and equipment. For personal safety, hydrogen sulfide has a strong stimulating effect on mucous membranes and is a strong nerve poison. As far as the environment is concerned, hydrogen sulfide pollutes water bodies and air, and sulfur dioxide produced by combustion leads to acid rain. For equipment, there are corrosion hazards in the process of crude oil extraction, storage, transportation and processing, which may cause major safety accidents. Different uses of biogas have different requirements for H ₂ S content. The corresponding national and industry standards stipulate that: if biogas is used for power generation, the concentration of H ₂ S must be less than or equal to 200~300mg/m ³ ; if biogas is used as vehicle fuel or Incorporated into the gas pipeline network, the concentration of H ₂ S must be less than or equal to 15 mg/m ³ . The mass concentration of H ₂ S in biogas is generally 1~12g/m ³ , far exceeding the standard. If no pretreatment is carried out, the H ₂ S contained in biogas will corrode metal pipes, instruments and meters. Therefore, H ₂ S must be removed before comprehensive utilization of biogas.

Whether domestic or foreign, there are many methods for hydrogen sulfide removal, which can be simply divided into wet desulfurization, dry desulfurization and biological desulfurization. Wet desulfurization is a method of removing hydrogen sulfide by reacting specific solvents such as sodium hydroxide and ammonia water with hydrogen sulfide. The solvent is recycled through the action of oxygen on the solvent. Due to the influence of the flow rate and flow rate of sodium hydroxide, hydrogen sulfide cannot be completely dissolved in it, and thiosulfate will be produced during the dissolution process, which will affect the desulfurization effect, and there are many investment, complicated operation and management, There are problems such as high desulfurization cost and the need to replace the absorption liquid. Dry desulfurization is a desulfurization method that uses oxygen and iron oxide as an oxidant to oxidize hydrogen sulfide into elemental sulfur or sulfide. Elemental sulfur plays a catalytic role in the absorption process. However, the dry desulfurization technology has problems such as large equipment area, discontinuous operation, difficult regeneration and replacement of desulfurizer, and low desulfurization efficiency. Biological desulfurization technology is a removal technology that converts H ₂ S into sulfate or elemental sulfur through microbial metabolic pathways. However, its desulfurization stability is easily affected by the ambient temperature.

Sulfide-oxidizing bacteria are mainly divided into three categories: filamentous sulfur bacteria, photosynthetic sulfur bacteria and colorless sulfur bacteria, most of which are chemoautotrophic. Among them, Thiobacillus is the most common colorless sulfur bacteria in soil and natural water. It is generally a sporeless brevibacterium, Gram-negative, with terminal flagella, and can oxidize sulfide into elemental sulfur or sulfate, or Oxidizes thiosulfate to sulfate. So far, eight species of Thiobacillus have been identified: Thiobacillus thiooxidans, Thiobacillus thiaulans, Thiobacillus denitrificans, Thiobacillus ferrooxidans, Thiobacillus naples, Thiobacillus neoformans, Thiobacillus intermedius and Thiobacillus incomplete metabolism . Among them, the first four are most widely used in the research of sulfate wastewater treatment.

Acidithiobacillus caldus is the only moderately thermophilic bacterium in the genus Acidithiobacillus . It is acidophilic and aerobic. The active sulfide is used as the energy source, CO ₂ in the air is used as the carbon source, and inorganic nutrients such as nitrogen and phosphorus are absorbed to synthesize bacterial cells. Generally, sulfur powder, HS ^- and H ₂ S are oxidized to H ₂ SO ₄ .

Contents of the invention

The purpose of the present invention is to provide a method for removing hydrogen sulfide in biogas by mesophilic acidophilic thiobacillus, which has the advantages of convenient operation, simple process flow, improved resource utilization value, cost saving, and improved desulfurization efficiency, etc., and can remove hydrogen sulfide stably and efficiently The hydrogen sulfide in biogas will help to improve the utilization level of biogas and break through the problem of biogas desulfurization.

The technical scheme adopted in the present invention is:

The specific operation steps of the method for removing hydrogen sulfide in biogas by mesophilic acidophilus thiobacillus are as follows:

1) Reactor A is a biogas generating device;

2) Thermophilic Thiobacillus biological desulfurization device B is equipped with 9K medium and 3%~5% inoculum of Thermophilic Thiobacillus, to remove hydrogen sulfide from biogas by Thermophilic Thiobacillus;

3) Detect once a day the change of the concentration of hydrogen sulfide in the device for removing hydrogen sulfide from biogas by mesophilic acidophilus thiobacillus;

Step 1) Biogas fermentation raw materials in biogas-producing reactor A include organic waste water, livestock and poultry manure, domestic garbage and straw, etc.

Step 1) The hydrogen sulfide concentration of the biogas fermentation liquid in the biogas-producing reactor A is 1000ppm-2000ppm.

Step 2) The medium formula of the mesophilic acidophilus thiobacterium is: A: 3.0 g ammonium sulfate, 0.1 g potassium chloride, 0.5 g dipotassium hydrogen phosphate, 0.5 g magnesium sulfate heptahydrate, 0.01 g calcium nitrate, distilled water 1L, adjust the pH to 2.5 with dilute sulfuric acid, and autoclave for 20 minutes. B: Ferrous sulfate 3~4%, distilled water 10mL, pass membrane to sterilize. Add B to A medium before inoculation.

Step ² ) The 9K culture medium was used to cultivate the mesophilic acidophilic ^{thiobacterium} to the logarithmic phase, and a small amount of bacterial liquid was taken to count the viable cells. individual/mL.

Step 2) The hydrogen sulfide concentration after the biogas passes through the reactor B equipped with the mesophilic acidophilus thiobacillus liquid for biological desulfurization is not more than 30ppm, preferably lower than 10ppm.

The mesophilic acidophilic thiobacillus is a bacterial strain with a strain number of 1.7296 preserved by the China Microorganism Culture Collection Center. In sulfide deposits, acid mineral water and soil, it plays an important role in bacterial metallurgy, coal desulfurization and treatment of sulfur-containing wastewater, and also plays an important role in the natural sulfur cycle. Dopson and Lindtrom studied and analyzed that the metabolites of mesophilic acidophilus Thiobacillus have the effect of surfactant, so that sulfur can be fully dissolved. The mesophilic acidophilic thiobacterium has a strong oxidation ability, and the cell growth of 1g can generate more than 20g of elemental sulfur. Adjust the amount of fermentation broth, based on the hydrogen sulfide content in the collected biogas meeting the required target, and adjust according to the treatment capacity target.

The cultivation method of the strain is as follows: carry out recovery culture of the mesophilic acidophilus Thiobacillus strain, absorb 0.3-0.5mL of 9K medium with a sterile pipette, drop it into the ampoule, shake gently, and dissolve the freeze-dried bacteria into a Suspended, absorb all the bacterial suspension, transfer it to 5mL of 9K medium, set the stirring speed at 170 r/min, and incubate at 40-45°C for 48-72h. Since the bacteria are stored in a freeze-dried manner, the delay period is relatively long. Inoculate the first-generation mesophilic acidophilic thiobacillus culture solution into 5mL liquid medium at an inoculum volume of 3% to 5%, and carry out two consecutive subcultures under the same culture conditions. Acidthiobacillus culture solution was inoculated into 80mL liquid medium at an inoculum volume of 3%~5%, and the mesophilic acidthiobacillus was cultured to the mid-logarithmic phase (4~5d) under the same culture conditions. The biogas was passed into the fermentation broth of mesophilic acidophilus thiobacterium for desulfurization. During the desulfurization process, the stirring speed was controlled at 170 r/min and the temperature was 40-45°C.

The positive effects of the present invention are: because the present invention uses mesophilic acidophilic thiobacterium to remove hydrogen sulfide in biogas, thereby significantly reducing the amount of hydrogen sulfide in in-situ biogas, and removing hydrogen sulfide that is harmful to the environment and equipment , high removal efficiency, reducing the cost and workload of subsequent desulfurization. Thermophilic Acidophilus Thiobacillus has a strong oxidizing ability, and more than 20 g of elemental sulfur can be produced by 1 g of cell growth. Li Yaxin et al. carried out experiments on the conversion of sulfide into elemental sulfur through an aerobic colorless sulfur bacteria biofilm reactor. Hydrogen sulfide The removal rate reaches 87%, and the desulfurization efficiency of the present invention reaches 98.24%, far exceeding the desulfurization efficiency of the prior art.

Description of drawings

Fig. 1 is the schematic diagram of reaction device;

Figure 2 is the hydrogen sulfide concentration change curve for desulfurization by mesophilic acidophilus Thiobacillus.

detailed description

The specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

The mesophilic acidophilic Thiobacillus is a strain with a strain number of 1.7296 preserved in the China Microorganism Culture Collection Center.

Example 1

This example provides an experiment for removing hydrogen sulfide in biogas by adding a strain of mesophilic acidophilus Thiobacillus.

Step 1: Carry out recovery culture of mesophilic acidophilus Thiobacillus strain, draw 0.3~0.5mL of 9K medium with a sterile pipette, drop it into the ampoule, shake gently, so that the freeze-dried bacteria dissolve and form a suspension, absorb all The bacterial suspension was transferred to 5 mL of 9K medium, and the stirring speed was 170 r/min, and the temperature was 40-45 ° C for 48-72 hours. Since the strains were stored in freeze-drying, the lag period was long, so the cultured one generation The mesophilic acidophilus thiobacillus culture solution was inoculated into 5mL liquid medium at an inoculum volume of 3%~5%, and the same culture conditions were carried out for two consecutive subcultures, and the recovered mesophilic acidophilus thiobacillus culture solution Inoculate 3%~5% of the inoculum into 80mL liquid medium, and culture the mesophilic acidophilus Thiobacillus to the mid-logarithmic phase (4~5d) under the same culture conditions. The medium formula of thermophilic acidophilus thiobacterium is: A: 3.0 g ammonium sulfate, 0.1 g potassium chloride, 0.5 g dipotassium hydrogen phosphate, 0.5 g magnesium sulfate heptahydrate, 0.01 g calcium nitrate, 1 L distilled water, dilute sulfuric acid Adjust the pH to 2.5 and autoclave for 20 minutes. B: Ferrous sulfate 3~4%, distilled water 10mL, pass membrane to sterilize. Add B to A medium before inoculation.

Step 2, biogas production: the chemical oxygen demand (COD) of alcohol wastewater is 29,000 mg/L, the pH is 3.78, the total nitrogen is 74.84 mg/L, the total volatile fatty acids (VFAs) are 21.45 mM, and the activated sludge can be volatilized The fermentation broth of VSS (36.49 g/L) was used as raw material for biogas production;

Step 3, take 2 sets of devices, numbered A0 and A1, add 80mL of the fermentation broth obtained in step 2 to the two devices A, add 80mL of 9K medium to the reactor B of the desulfurization device numbered A1, and inoculate 3%~5% The mesophilic acidophilus bacterium liquid obtained in step one;

Step 4: Put devices A0 and A1 into a shaker with a rotation speed of 170 r/min and a temperature of 40 °C to react for 6 days, and record the change of hydrogen sulfide concentration.

From Figure 2, it can be concluded that the concentration of hydrogen sulfide in the control sample without adding mesophilic thiobacterium was 1423.05 ppm, and the concentration of hydrogen sulfide in the biogas produced by the desulfurization device added with mesophilic thiobacterium was 22.41 ppm on the first day, and the concentration of hydrogen sulfide in the sixth day was 22.41 ppm. The concentration of hydrogen sulfide in the biogas produced every day is 5.93 ppm, and the desulfurization effect is obvious. It can be seen that the mesophilic acidophilus Thiobacillus can significantly reduce the content of hydrogen sulfide, and the removal effect of hydrogen sulfide is better.

Claims (6)

1. A method for removing hydrogen sulfide in biogas by mesophilic acidophilic thiobacterium, characterized in that: the biogas to be treated is passed into the fermentation broth of mesophilic acidophilic thiobacterium, and removed by fermentation of mesophilic acidophilic thiobacterium For hydrogen sulfide in biogas, the fermentation temperature is 40~45℃. 2. the method for removing hydrogen sulfide in biogas by the mesophilic acidophilic thiobacillus according to claim 1, is characterized in that: the fermented liquid of the mesophilic acidophilic thiobacterium is inoculated into the Obtained by fermentation culture in fermentation medium, the formula of said fermentation medium includes component A and component B, component A is: ammonium sulfate 3.0 g, potassium chloride 0.1 g, dipotassium hydrogen phosphate 0.5 g, heptahydrate Magnesium sulfate 0.5 g, calcium nitrate 0.01 g, distilled water 1 L, adjust pH to 2.5 with dilute sulfuric acid, autoclave for 20 min; component B: ferrous sulfate 3~4%, distilled water 10 mL, sterilize through membrane; before inoculation Component B was added to component A to obtain a fermentation medium. 3. The method for removing hydrogen sulfide in biogas by the mesophilic acidophilic thiobacillus according to claim 1, characterized in that: the mesophilic acidophilic thiobacterium is the strain number 1.7296 preserved by the China Microorganism Culture Collection Center strain. 4. The method for removing hydrogen sulfide in biogas by mesophilic acidophilic thiobacillus according to claim 1, characterized in that the number of viable cells in the fermentation broth of mesophilic acidic thiobacterium is 2.0×10 ⁶ /mL ~10.0×10 ⁶ cells/mL. 5 . The method for removing hydrogen sulfide in biogas by mesophilic acidophilus thiobacillus according to claim 1 , characterized in that the raw material for biogas fermentation includes at least one of organic wastewater, livestock and poultry manure, domestic garbage or straw. 6 . The method for removing hydrogen sulfide in biogas by mesophilic acidophilus thiobacillus according to claim 1 , wherein the concentration of hydrogen sulfide after the biogas is desulfurized by the fermentation liquid of mesophilic acidophilus thiobacterium is not more than 30 ppm.