Implantação e otimização operacional de um sistema para remoção de sulfeto de hidrogênio, com uso de soluções de Fe/EDTA, de biogás proveniente de efluentes de suinocultura

Abstract

Alternative energy advances worldwide due to environmental problems resulting from the collection and use of conventional energy sources. An important alternative fuel, from the anaerobic treatment of waste or effluent, is biogas. Biogas because of its concentration of methane (CH4), has been used to generate electricity. However, the process efficiency is reduced due to high concentrations of carbon dioxide (CO2) and hydrogen sulfide (H2S). The CO2 reduces the calorific value of biogas and H2S has corrosive effect on production and energy conversion structures. Therefore, it is important to develop technologies that help reduce these two gases in biogas. This study aimed to investigate the influences of solutions containing chelated iron (Fe) with EDTA (Fe / EDTA) and the ratio of liquid flow and biogas (L / G), countercurrent in a tower absorption in removal of CO2 and H2S. To evaluate the removal efficiencies at different operating conditions, it was proposed a Central Composite Rotational Design (CCRD) 2², with three experiments in the central point and four in axial points. In the tests performed, the Fe/EDTA concentrations were adjusted between 0.100 and 0.200 mol L-1 and L/G ratio between 0.73 and 1.27. For the H2S in the range of values studied, the two variables, the concentration of Fe/EDTA and L/G were significant (p < 0.05) and the maximum efficiency was 97.84%. In relation to CO2 under the same conditions, the efficiency achieved was 18.19%. From analysis of the results with high removals for H2S and satisfactory for CO2, it can be concluded in general that this process of biogas purification allows an improvement in the quality of the biogas as a fuel and reduces efficiently the quantities H2S at levels that cause little harm to the process.