Remoção biológica de gás sulfídrico concentrado para tratamento do biogás

Abstract

The biogas is a product of the microbiological degradation process of organic matter. Biogas consists mainly in methane, carbon dioxide and small amounts of hydrogen, nitrogen and hydrogen sulfide. The high methane concentration in biogas made it an attractive fuel and its use solves a problem of emission, since methane has a polluting effect superior than of carbon dioxide. The hydrogen sulfide, although present in small amounts, is a toxic and highly corrosive gas, and besides being a major pollutants of the atmosphere. In this sense, this work is dedicated to investigate the removal efficiency for H2S biofiltration process in a synthetic biogas flow. The biological processes it is an interesting alternative as compared to physical-chemical processes, and the biofiltration represents the most widely used. Performed an experimental bioreactor biofilter model and evaluated vegetable sponge as a packing for immobilization of microorganisms of the genus T. thioparus and activated sludge as medium for acclimatization of bacteria. The experiment took place within 31 days, with a flow gas of 0.02 m³.h-1, a residence time of empty bed of 190s and an affluent concentration of 10000 ppmv. During the study the system temperature kept in mesophilic range registering 28.3°C as average, however the pH range preserved below of recommended at T. thioparus bacteria, reaching pH = 2.48. The moisture of the environment remained around 55%. The removal efficiency achieved was 67% corresponding to an effluent concentration of 3314 ppm to an elimination capacity of 177 g.m-3h-1. However, the final concentration of methane decreases from 59.9% to 49.5% this is explained by the dilution of the gas by supplied air system, which is essential to feed the microbiological requirements for the H2S oxidation. The results show that it is possible to apply the vegetable sponge to biofiltration of H2S.