Method for treating hydrogen sulfide-containing tail gas based on microalgae

Abstract

The invention provides a method for treating hydrogen sulfide-containing tail gas based on microalgae, and relates to a technology for converting hydrogen sulfide into solid microalgae biomass by utilizing the photosynthesis capacity of the microalgae so as to achieve the purpose of removing hydrogen sulfide. The technology comprises the following steps that tail gas containing hydrogen sulfide is fed into a reactor, hydrogen sulfide is converted into microalgae biomass through specific microalgae absorption, accumulation, conversion, photosynthesis and other mechanisms, nutrients and energy are generated, and sufficient oxygen and light sources are provided through an aeration system; meanwhile, conditions such as temperature, ORP (Oxidation Reduction Potential) and PH (Potential of Hydrogen) value in the reactor are adjusted to promote the growth and metabolism of the microalgae. And finally, collecting and treating the microalgae to achieve the purpose of removing hydrogen sulfide. The method provided by the invention has the advantages of high desulfurization efficiency, low treatment cost, simplicity and convenience in operation and the like, and can be widely applied to the fields of sulfur-containing tail gas treatment, resource recovery and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of gas purification, and in particular relates to a method for treating tail gas containing hydrogen sulfide based on microalgae. Background Art

[0002] Air pollution and atmospheric pollutants have become serious problems in public health and environmental protection. Hydrogen sulfide is a toxic and harmful gas that causes serious harm to the health of humans, animals and plants and the environment. It is widely present in industries that produce waste gas, such as sewage treatment plants, chemical plants and food processing plants. Traditional methods for removing hydrogen sulfide include chemical methods, physical methods and biological methods. Among them, the chemical method mainly uses chemical reagents such as oxidants, reductants and absorbents to remove hydrogen sulfide. This method has problems such as high cost, complex operation and secondary pollution. The physical method mainly uses physical processes such as adsorption and absorption to remove hydrogen sulfide. Although this method is more environmentally friendly than the chemical method, it has low efficiency. The biological method uses the ability of microbial desulfurization strains to metabolize hydrogen sulfide to remove hydrogen sulfide, which has the advantages of low cost, high efficiency, simple operation and environmental protection. However, the current method of removing hydrogen sulfide by microorganisms has defects such as slow microbial growth reaction rate and strain sensitivity to environmental conditions. Therefore, it is of great significance to develop a new desulfurization technology that is efficient, economical and environmentally friendly.

[0003] Microalgae refers to a type of microscopic single-cell colony, which can generally only be identified under a microscope. It is the lowest autotrophic aquatic organism and is widely found in various water bodies in nature, including oceans, fresh water, ponds, rivers, etc. Microalgae plays an important role in the entire earth's ecosystem. As the largest solar assimilation in the ecosystem, microalgae provide more than 50% of the primary productivity and oxygen for the earth with less than 1% of the biomass of higher plants, and are the most photosynthetic efficiency of the biological group.

[0004] There are many types of bioenergy that can be developed and their sources are wide-ranging. Among the many raw materials for producing bioenergy, microalgae have become a typical representative of the third generation of bioenergy due to their high photosynthesis efficiency, fast growth rate, high oil content, no occupation of arable land, can be cultivated using wastewater and waste gas, and can be produced all year round. They can be used to produce a variety of products such as health foods, cosmetics, medicines, biofuels, etc. In addition, microalgae can also be used for biological adsorption, water quality treatment and environmental purification.

[0005] At present, microalgae is only one of the tools for biological carbon fixation and removal of other harmful gases. However, the energy crisis has become increasingly prominent in recent years. Therefore, the use of microalgae resources to help solve environmental and energy problems simultaneously has attracted much attention. Microalgae desulfurization technology is still in the research stage, and there are few technologies for removing hydrogen sulfide using microalgae, and they are mainly used for biogas purification. Meier et al. used Chlorella to purify biogas, completely removed hydrogen sulfide gas in biogas, and found that there were high dissolved oxygen conditions in the system and the final oxidation product of sulfide was sulfate. Prandini et al. used microalgae to remove 3000ppm of hydrogen sulfide under autotrophic conditions. Unlike sulfur-oxidizing bacteria, the hydrogen sulfide removal process of microalgae can be attributed to direct assimilation and oxidation. Hydrogen sulfide is mainly oxidized to sulfide, thiosulfate and sulfite in the microalgae system. Subsequently, these sulfur oxides will be further oxidized by oxygen to form sulfate, which serves as the main sulfur source for the assimilation process of microalgae. The above results prove that microalgae has the potential to remove hydrogen sulfide.

[0006] The technology of microalgae desulfurization is one of the current research hotspots and is still in the stage of continuous research and development and improvement. Compared with traditional chemical absorption and biological desulfurization methods, microalgae desulfurization technology has the advantages of low cost, low energy consumption, long service life, and no secondary pollution. It has broad application prospects and very important significance. Summary of the invention

[0007] The present invention aims at the problems and deficiencies in the prior art and provides a method for utilizing the photosynthesis and unique metabolic function of microalgae to achieve the treatment of gas containing hydrogen sulfide under simple and efficient conditions, thereby achieving the purpose of removing harmful gases. Specifically, specific microalgae are selected, and the cultivation environment of the microalgae and the contact conditions with hydrogen sulfide are optimized to enable them to have the ability to achieve efficient desulfurization. The microalgae produce oxygen and other organic matter through photosynthesis, and the metabolic function of the microalgae is used to react hydrogen sulfide with oxygen to form harmless substances such as sulfur, sulfate and water.

[0008] To this end, the first aspect of the present invention provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The process generally includes components such as an absorption reactor, a photobioreactor, a microalgae aeration system, and a circulation system.

[0009] According to the method provided by the present invention, microalgae treatment of hydrogen sulfide-containing tail gas mainly includes the following steps: S1: The pretreated tail gas containing hydrogen sulfide is fed into the input end of the primary reactor, the input end of the secondary reactor is connected to the output end of the primary reactor, and the output end of the secondary reactor is connected to the tail gas discharge; S2: The microalgae desulfurization liquid enters the liquid distributor from the upper part of the primary reactor and the secondary reactor, is evenly sprayed in the reactor, fully contacts with the hydrogen sulfide-containing tail gas to absorb hydrogen sulfide, and is discharged from the bottom; S3: The discharged microalgae desulfurization liquid is pumped into the heater and then enters the microalgae photoreactor to adjust the light source, promote the photosynthesis of microalgae to produce nutrients and energy, and convert part of the sulfide in the liquid into solid microalgae biomass; S4: The solution flowing out of the photoreactor enters the microalgae aeration reactor, and air is introduced through the aeration system. At the same time, the temperature, ORP, DO, pH value and other conditions in the reactor are adjusted to promote the sulfide to be catalyzed by the enzymes of the microalgae cells, to react and metabolize, to generate sulfur element and sulfate, and thus to carry out sulfur conversion; S5: The solution in the microalgae reactor is pumped into the primary reactor and the secondary reactor for recycling.

[0010] In the present invention, the primary reactor and the secondary reactor can be used in series or separately.

[0011] In the present invention, the main body of the microalgae photoreactor is generally made of transparent materials such as organic glass or plastic film, and the reactor structure can be a photobioreactor type of different sizes such as flat plate, column, tube, cone, etc.

[0012] In the present invention, the light source used in the microalgae photoreactor is white light or natural light with a wavelength between 400 and 700 nm. Photoperiod: 6 to 18 hours.

[0013] In the present invention, the temperature in the microalgae photoreactor and the microalgae aeration reactor is adjusted to 15-35°C.

[0014] In the present invention, the pH value in the microalgae photoreactor and the microalgae aeration reactor is adjusted to be 6.0-8.5.

[0015] In the present invention, the ORP in the microalgae photoreactor and the microalgae aeration reactor is adjusted to -500 to -200 ev.

[0016] In the present invention, the DO value in the microalgae photoreactor and the microalgae aeration reactor is adjusted to 2-10 mg / L.

[0017] In the present invention, the microalgae desulfurization liquid is prepared with sodium carbonate or potassium carbonate at a concentration of 0.5 to 10 g / L.

[0018] In the present invention, the density of the microalgae in the microalgae desulfurization liquid is 0.1-2.0 g / L.

[0019] In the present invention, the ORP value of the microalgae aeration reactor is interlocked with the air intake volume.

[0020] In the present invention, the microalgae aeration reactor periodically takes out microalgae biomass, and the microalgae biomass can be added into a photoreactor.

[0021] The second aspect of the present invention provides an optimized cultivation method for microalgae for treating tail gas containing hydrogen sulfide: S1: Select appropriate microalgae species and perform pre-cultivation; S2: The pre-cultured microalgae are inoculated into a culture medium containing appropriate nitrogen, phosphorus and carbon sources. The culture time is generally about 5 to 20 days.

[0022] S3: Introduce hydrogen sulfide for co-cultivation to optimize the growth and reproduction of microalgae in a hydrogen sulfide environment and increase the metabolic activity and resistance of microalgae to hydrogen sulfide; S4: Under appropriate light intensity and light cycle, the pH value of the culture solution is maintained between 6.5 and 8.0, the temperature is maintained at 15 to 40°C, and an appropriate amount of oxygen is supplied to promote the growth and metabolism of microalgae; S5: Collecting microalgae.

[0023] In the present invention: the microalgae include but are not limited to one or a mixture of green algae, blue algae, diatoms, and Chlamydomonas; In the present invention, the microalgae culture methods include static culture, suspension culture, flow culture and continuous culture. Beneficial Effects

[0024] The present invention aims to provide a method for treating tail gas containing hydrogen sulfide based on microalgae. The method adopts a new type of biological treatment technology to achieve efficient removal of hydrogen sulfide through the adsorption, transformation, metabolism and photolysis of microalgae. Compared with the traditional hydrogen sulfide treatment method: (1) This method utilizes the photosynthesis and respiration of microalgae to absorb, transform and fix hydrogen sulfide in the exhaust gas. At the same time, a large amount of oxygen is released during the growth of microalgae, which can further oxidize hydrogen sulfide and transform it into non-toxic substances such as sulfur, sulfate and water, thereby achieving the purpose of efficiently removing hydrogen sulfide.

[0025] (2) Microalgae is a naturally grown biological resource with simple growth conditions, easy cultivation, low cost, and is suitable for different environments and scenarios. It has high applicability, no negative impact on the environment, and is reusable and has good sustainability. This method uses high-density cultivation and continuous gradient aeration to effectively improve the utilization efficiency and desulfurization efficiency of microalgae.

[0026] (3) Using microalgae to treat waste gas containing hydrogen sulfide will not cause secondary pollution, will not produce other waste materials and chemical substances, and will have little pollution to the environment. In addition, the useful substances produced by microalgae metabolism can be recycled to reduce pollutant emissions. It can be widely used in the fields of industrial waste gas and sewage treatment, which can reduce atmospheric pollutant emissions and protect the environment. At the same time, the generated biomass materials can be recycled to achieve sustainable development.

[0027] (4) Microalgae hydrogen sulfide removal technology has the advantages of low cost, high treatment efficiency, energy saving and environmental protection. In addition, through reasonable microalgae cultivation and extraction methods, efficient recovery and reuse of microalgae can be achieved, further improving the economy and sustainability of this method. It has strong practicality and social value and has broad application prospects and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a schematic diagram of the process flow of a method for treating tail gas containing hydrogen sulfide based on microalgae according to an embodiment of the present invention.

[0029] In the figure, 1 is a primary reactor; 2 is a secondary reactor; 3 is a microalgae photoreactor; 4 is a microalgae aeration reactor; 5 and 6 are circulation pumps; and 7 is an electric heater. Implementation

[0030] In order to make the present invention easier to understand, the present invention will be described in detail below in conjunction with embodiments and examples. These embodiments are only illustrative and are not intended to limit the scope of application of the present invention.

[0031] All reagents used in the examples were commercially available analytical grade reagents.

[0032] Embodiment A method for treating tail gas containing hydrogen sulfide based on microalgae, wherein the microalgae are first selected and optimally cultivated: S1: Select green algae, blue algae, and chlorella and inoculate them in 9 culture vessels, marked as A1, A2, A3, B1, B2, B3, C1, C2, and C3; S2: Add A1, B1, and C1 to the nutrient solution in batches, illuminate for 12 hours under white light, maintain the temperature at 25°C, set the pH value of the culture solution to 7.0-7.5, and culture for 15 days; S3: A2, B2, and C2 were added to the nutrient solution in batches, and the illumination time was 12 hours under white light environment, the temperature was maintained at 25°C, 50ppm hydrogen sulfide gas was introduced for optimized cultivation, and air was introduced. The pH value of the culture solution was 7.0-7.5, and the culture period was 15 days; S4: A3, B3, and C3 were added to the nutrient solution in batches, the illumination time was 12 hours under white light environment, the temperature was maintained at 25°C, 50ppm hydrogen sulfide gas was introduced twice for optimized culture, and air was introduced. The pH value of the culture solution was 7.0-7.5, and the culture period was 15 days; S5: Collecting microalgae: The microalgae can be collected by sedimentation, filtration, centrifugation, etc.

[0033] The cultured microalgae were used to remove hydrogen sulfide. The process flow is shown in the attached Figure 1 . Example

[0034] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae A1) is added to a desulfurization experimental device to prepare a microalgae desulfurization solution A1-1 containing 7 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 12L-12D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 8.0, an ORP of -400ev, and a DO of 4 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0035] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae A2) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution A2-1 containing 6.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 10L-14D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 8.0, an ORP of -380ev, and a DO of 4 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0036] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae A3) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution A3-1 containing 6.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 8L-16D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 7.8, an ORP of -380ev, and a DO of 3.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0037] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae A3) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution A3-2 containing 6.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the secondary reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and then is discharged from the top to the air; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 10L-14D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 20°C, a pH value of 7.8, an ORP of -380ev, and a DO of 4.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0038] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae B1) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution B1-1 containing 7.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 12L-12D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 8.0, an ORP of -400ev, and a DO of 4 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0039] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae B2) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution B2-1 containing 7.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 10L-14D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 8.0, an ORP of -400ev, and a DO of 4 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0040] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae B3) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution B3-1 containing 7.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 8L-16D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 7.8, an ORP of -380ev, and a DO of 3.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0041] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae B3) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution B3-2 containing 7.5 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the secondary reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and then is discharged from the top to the air; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 10L-14D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 20°C, a pH value of 7.8, an ORP of -380ev, and a DO of 4.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0042] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae C1) is added to a desulfurization experimental device to prepare a microalgae desulfurization solution C1-1 containing 8 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 12L-12D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 25°C, a pH value of 8.0, an ORP of -400ev, and a DO of 4 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0043] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae C2) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution C2-1 containing 8 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 10L-14D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 20°C, a pH value of 7.8, an ORP of -360ev, and a DO of 3.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0044] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae C3) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution C3-1 containing 7.6 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the first reactor, is roughly desulfurized by the microalgae solution sprayed down, and is discharged from the top. It continues to enter the gas distributor of the second reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and is discharged from the top to empty; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 8L-16D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 20°C, a pH value of 7.8, an ORP of -360ev, and a DO of 3.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas. Example

[0045] This embodiment provides a method for treating hydrogen sulfide-containing tail gas based on microalgae. The cultured microalgae desulfurization liquid (green algae C3) is added to the desulfurization experimental device to prepare a microalgae desulfurization solution C3-2 containing 7.6 g / L of sodium carbonate. The specific desulfurization steps are as follows: S1: The raw gas containing hydrogen sulfide enters the gas distributor of the secondary reactor, fully contacts with the microalgae solution from top to bottom, absorbs hydrogen sulfide, and then is discharged from the top to the air; S2: The microalgae solution absorbing hydrogen sulfide at the bottom of the primary reactor and the secondary reactor is pumped into the microalgae photoreactor; S3: In the microalgae photoreactor, white light was used for illumination, the photoperiod was 10L-14D, and the temperature was maintained at 25°C; S4: The microalgae solution overflowing from the microalgae photoreactor enters the microalgae aeration system, where air is introduced to maintain a temperature of 20°C, a pH value of 7.8, an ORP of -370ev, and a DO of 4.5 mg / L; S5: The solution coming out of the microalgae aeration system is pumped into the liquid distributors of the primary reactor and the secondary reactor through a circulation pump to circulate and absorb the hydrogen sulfide waste gas.

[0046] Application Examples A certain concentration of H2S raw gas was prepared, and the microalgae desulfurization solutions of Examples 1-12 were used to desulfurize the H2S raw gas. The results are shown in Table 1.

[0047] Table 1 Data sheet of desulfurization of microalgae solution As can be seen from Table 1, the method provided by the present invention has a high removal capacity for H2S-containing waste gas, and can efficiently remove H2S gas while maintaining the metabolic growth of microalgae.

[0048] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for treating tail gas containing hydrogen sulfide based on microalgae, characterized in that: The treatment of tail gas containing hydrogen sulfide mainly includes the following steps: S1: The pretreated tail gas containing hydrogen sulfide is fed into the input end of the primary reactor, the input end of the secondary reactor is connected to the output end of the primary reactor, and the output end of the secondary reactor is connected to the tail gas discharge; S2: The microalgae desulfurization liquid enters the liquid distributor from the upper part of the primary reactor and the secondary reactor, is evenly sprayed in the reactor, fully contacts with the hydrogen sulfide-containing tail gas to absorb hydrogen sulfide, and is discharged from the bottom; S3: The discharged microalgae desulfurization liquid is sent to the heater and then enters the microalgae photoreactor to adjust the light source, promote the photosynthesis of microalgae to produce nutrients and energy, and convert part of the sulfide in the liquid into solid microalgae biomass; S4: The solution flowing out of the microalgae photoreactor enters the microalgae aeration reactor, and air is introduced through the aeration system. At the same time, the temperature, ORP, DO, and pH value in the reactor are adjusted to promote the catalysis of sulfide by the enzymes of the microalgae cells, to carry out reaction metabolism, to generate sulfur element and sulfate, and to carry out sulfur conversion; S5: The solution from the microalgae aeration reactor is sent to the primary reactor and the secondary reactor for recycling.

2. The method according to claim 1, characterized in that: The microalgae first need to be optimized for cultivation, and the specific optimization cultivation method is as follows: S1: Select microalgae species and perform pre-cultivation; S2: inoculating the pre-cultured microalgae into a culture medium containing nitrogen, phosphorus and carbon sources, and the culture time is about 5 to 20 days; S3: Introduce hydrogen sulfide for co-cultivation to optimize the growth and reproduction of microalgae in a hydrogen sulfide environment and increase the metabolic activity and resistance of microalgae to hydrogen sulfide; S4: Under the light intensity and light cycle, the pH value of the culture solution is maintained between 6.5 and 8.0, the temperature is maintained at 15 to 40°C, and oxygen is supplied to promote the growth and metabolism of microalgae; S5: Collecting microalgae.

3. The method according to claim 1, characterized in that: The primary reactor and the secondary reactor are used in series or individually.

4. The method according to claim 1, characterized in that: The main body of the microalgae photoreactor is made of transparent material such as organic glass or plastic film, and the reactor structure is a flat plate, column, tube, or conical photobioreactor type of different sizes.

5. The method according to claim 1, characterized in that: The light source used by the microalgae photoreactor is white light or natural light with a wavelength between 400 and 700 nm, and the illumination time is 6 to 18 hours.

6. The method according to claim 1, characterized in that: The temperature in the microalgae photoreactor and the microalgae aeration reactor is adjusted to 15-35°C, the pH value in the microalgae photoreactor and the microalgae aeration reactor is adjusted to 6.0-8.5, the ORP is adjusted to -500-200ev, and the DO value is adjusted to 2-10mg / L.

7. The method according to claim 1, characterized in that: The microalgae desulfurization liquid is prepared with sodium carbonate or potassium carbonate at a concentration of 0.5 to 10 g / L.

8. The method according to claim 1, characterized in that: The density of the microalgae in the microalgae desulfurization liquid is 0.1-2.0 g / L.

9. The method according to claim 1 or 6, characterized in that: The ORP value of the microalgae aeration reactor is interlocked with the air intake volume for control.

10. The method according to claim 2, characterized in that: The microalgae include a mixture of one or more of green algae, blue algae, diatoms and Chlamydomonas.

11. The method according to claim 2, characterized in that: The microalgae culture methods include static culture, suspension culture, flow culture and continuous culture.

12. The method according to claim 1, characterized in that: The microalgae aeration reactor periodically takes out microalgae biomass, and the microalgae biomass can be added into the microalgae photoreactor.

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