After anaerobic treatment in the process of resource utilization of organic waste, the biogas produced contains a variety of gases, of which CH4 is a very good clean energy, but H2S is a corrosive gas with odor, which is highly corrosive to subsequent pipelines, biogas cabinets and gas combustion equipment, and the concentration of SO2 produced after H2S combustion is very high, The pollution to the natural environment is very serious. Therefore, H2S in biogas shall be removed before biogas utilization to avoid corrosion to later equipment.
The alkaline biological desulfurization process is divided into two steps:
1： The H2S in biogas is converted from gas phase to liquid phase through desulfurization reactor. The desulfurization reaction tower is a scrubber, and the biogas enters from the bottom of the tower and passes through the filter bed. The slightly alkaline circulating water enters from the top of the tower, is dispersed by the special nozzle, and falls freely through the filter bed. The special filter material can further disperse the biogas and circulating water, prolong the contact time and improve the washing effect. The circulating water containing sulfide flows into the regeneration tank from the bottom of desulfurization reaction tower.
2： The regeneration tank completes the oxidation process of sulfide in circulating water. A large number of desulfurization bacteria (mainly colorless sulfur bacteria) in circulating water will feed on sulfide, convert sulfide into their own nutrients, enter the self circulation process of microorganisms, and discharge elemental sulfur and hydroxyl from bacteria, so as to achieve the purpose of degradation.
The regeneration tank creates a living environment for desulfurizing bacteria in circulating water, and the heat exchanger in the regeneration tank provides heat to the circulating water to ensure that the temperature of circulating water is about 33-34 degrees. The aeration head provides oxygen to the circulating water to ensure proper dissolved oxygen in the circulating water. Desulfurizing bacteria produce by-products elemental sulfur and sulfate by digesting sulfide metabolism in circulating water. Sulfate will reduce the pH value of circulating water. It is also necessary to add some alkali solution to neutralize the 5% sulfate through the dosing system.