Study On Integrated And External Biological Desulfurization At Anaerobic Fermentation Reactors

Desulfurization is an indispensable step in the biogas purification processes, which directly affects the subsequent biogas use. Biogas desulfurization methods can be divided into three general categories: dry, wet, and biological processes. Currently, biological processes become a research hotspot. According to the domestic and foreign studies and applications, two bio-desulfurization methods were divided: integrated and external biological technology at anaerobic fermentation reactors. Different pilot-scale tests were carried on with the two techniques. This dissertation, with the experience of the initial tests, the quantitative analysis of some effect factors, and the discussion of the desulfurization performance, characteristics, prospects, is expected to provide a clue or a reference for technique research and engineering application.Integrated biological desulfurization of biogas was tested under micro-aerobic condition with appropriate amount of air injected into CSTR. In the experiments, H₂S removal rate was increased with the increase of air feed rate. At a rate of 2.50ml/min air feed, the removal efficiency of H₂S in biogas were stable at 100% all the time. After desulfurization, methane （CH₄） content in biogas was decreased slightly, while COD removal rate was increased. And all the changes did not affect the quality of biogas production. In addition, the sulfur was mainly accumulated in the slurry with the form of sulfide and sulfur-containing solid.External biological method was also tested. A small amount of air was injected into the bio-packing towers for removing H₂S. The bio-packing towers were filled with plastic waste and compost respectively, and they also supplied the desulfurization bacterium. Studies showed that removal efficiency of H₂S in biogas was higher at a higher rate of air feed. When the air feed rate was 2.50ml/min, H₂S could be removed completely by the two kinds fillers. Of course, the compost’s desulfurization ability was relatively stronger than the plastic waste’s. And after adaptation under the rate of 0.63ml/min air feed, the removal efficiency was reached 100% in the compost tower. CH₄ concentration in biogas after desulfurization was slightly lower than before, but not necessary. The bottom of the compost filler was the main desulfurization part, and the bottom sulfur accounted for 69.8% in total sulfur in the compost tower.