Avaliação técnica e econômica do efeito da adição de minério de ferro de rejeito de mineração na produção de biogás de excrementos da suinocultura

Abstract

Anaerobic digestion represents a strategic treatment method to high generation of manure by swine, generating biogas, a type of renewable fuel and an organic substrate. However, the high variability of methane and cost of operation make its dissemination in Brazil minimal and slow. In this line, the innovation of the present study consists in the use of iron ore tailings to optimize this process in pig farming. For the study, mineralogical and toxicological analyzes were carried out of the mining waste from the Conceição II (Vale do Rio Doce Company), followed by the anaerobic digestion of the excrement in sequential batch reactors (SBRs) with tailings / substrate dosages of 1.56 kg / m3, 3.12 kg / m3 and 4.69 kg / m3 to then assess the use of the additive in the process by analyzing the reduction of organic constituents, trace elements, production and composition of the biogas generated. In the last part of the study, the toxicity of the substrate with the species E. Crypticus was analyzed, followed by the economic analysis of the entire process using uncertainty methodology. The results indicated the presence of the elements Fe, K, Si, Al, Mg, Ca, Na and P in the additive, obtaining the production of 8.41.10-2 m3 CH4 / kg substrate and reductions in organic load of 77% and 81, 4% for the maximum applied dosage. The level cost of electricity ranged from 350 - 450 R$ / MWh for scenarios with 50 thousand and 200 thousand heads, which values are not competitive in relation to other renewable energy sources in the country. The application of the substrate in the soil was highly toxic for organisms in all treatments. In this sense, although the promising use of this residue in this technology, further studies must be carried out to decrease the trace elements in the fertilizer generated