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The most common methods for desulfurizing biogas: Biogas desulfurization methods can be classified into dry methods, wet methods, and biological desulfurization methods based on their principles. 1. Dry desulfurization: This is a type of dry desulfurization process that involves the use of a desulfurization tower of a certain height; biogas passes through the desulfurizing agent from bottom to top, thereby removing H2S and achieving desulfurization. This method is divided into adsorption desulfurization and catalytic conversion methods. Adsorption makes use of the strong adsorptive capacity of sulfides for solid desulfurization, primarily targeting iron oxide, activated carbon, zinc oxide, molecular sieves, etc. The catalytic conversion method uses a hydrodesulfurization catalyst to convert the organic sulfur compounds contained in the hydrocarbon feedstock into hydrogen sulfide, which can then be removed by other methods. The hydrodesulfurization catalyst is a combination of cobalt-molybdenum-alumina used for the hydroconversion of zinc oxide, enabling precise desulfurization. 2. In the wet desulfurization method, the desulfurizing agent is affected by the temperature of the liquid; it is generally used for the desulfurization of gases with high sulfur content and strong desulfurization capacity. Based on their different desulfurization mechanisms, they are classified into chemical absorption, physical absorption, physicochemical absorption, and wet oxidation. Chemical absorption is commonly used in wet flue gas desulfurization processes, with weakly alkaline solvents being employed for the absorption process as well as for chemical reactions and absorption; after H2S is absorbed, the temperature is adjusted, and reduced pressure is applied during regeneration. Lye absorption is one of the most commonly used chemical absorption desulfurization methods, and sodium carbonate solution, lime milk, or sodium hydroxide solution can be used as absorbents. The physical absorption method involves using organic solvents to carry out physical adsorption for desulfurization under certain pressure; thereafter, the pressure is reduced to release the sulfide gases, allowing the solvent to be regenerated. The physical-chemical absorption method combines the physical and chemical absorption properties of two solutions, resulting in a high desulfurization efficiency. Wet oxidation can generally only remove hydrogen sulfide, and cannot or can only remove a small amount of organic sulfur. The most commonly used wet oxidation method is the ADA method. 3. Biological desulfurization: Biological desulfurization makes use of light energy and autotrophic microorganisms to convert sulfur. Sulfur metabolism processes of different types of sulfur bacteria in natural water. Different types of microorganisms are distributed differently in various regions due to their own metabolic characteristics. There is sufficient dissolved oxygen on the water surface, where organisms can be in an aerobic state with H2S and convert it into elemental sulfur; at the bottom of the anaerobic zone, organic matter produces H2S. And in the photoautotrophic zone, there is still sufficient light as well as H2S. The H2S-containing gas is fed directly into the reactor, and both the absorption and oxidation processes take place within the reactor. To meet the requirements for microbial nutrition and the cleaning of the filter layer, the mixed solution circulation system needs to operate continuously. During the desulfurization process in the biological filter tower, the supply system for the mixed solution in the biological trickling filter and biological filter operates intermittently. In the two-stage desulfurization process, H2S in the gas phase is absorbed into the desulfurization reactor through adsorption belts, while the oxidation of sulfides takes place under the action of autotrophic microorganisms.