Aplicação de reatores anaeróbios para remoção de sulfato de águas de drenagem ácida de minas
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
Resumo
Descrição
O presente trabalho teve, por objetivo principal, analisar a remoção de sulfato em águas de drenagem ácida de minas em dois tipos de reatores anaeróbios, um com crescimento granular (UASB) e outro com biomassa aderida (RAHLF). Estudos anteriores publicados na literatura apresentam resultados positivos quanto ao tratamento anaeróbio de drenagem ácida de minas, entretanto, na maioria deles, é aplicado um tratamento preliminar à água residuária antes do tratamento principal. Esse trabalho avaliou a operação de reatores anaeróbios sem prévio tratamento da drenagem ácida sob diferentes variáveis. Para o reator anaeróbio horizontal de leito fixo (RAHLF), foram analisadas as variáveis relação DQO/\'SO IND.4\'POT.2-\', correção do pH afluente, carga de sulfato aplicada e a recirculação da fase líquida. Os resultados mostraram que a redução da carga de sulfato aplicada foi o fator determinante para os bons resultados de remoção, encontrados ao longo da operação dos reatores (70% de remoção de sulfato e 75% de remoção de DQO). A relação DQO/\'SO IND.4\'POT.2-\' também foi importante e quando utilizada a relação estequiométrica de 0,67, a eficiência de remoção de sulfato atingiu níveis superiores a 70% com pequeno acúmulo de ácido acético no efluente. Para a operação do reator anaeróbio de manta de lodo (UASB), as variáveis analisadas foram o volume da manta de lodo, a relação DQO/\'SO IND.4\'POT.2-\', a carga de sulfato aplicada e a recirculação da fase líquida. Como para o RAHLF, a redução da carga de sulfato aplicada foi essencial para o melhor funcionamento do UASB. A relação DQO/\'SO IND.4\'POT.2-\' de 1,0 promoveu melhora na eficiência do reator, quando comparada à relação estequiométrica e a recirculação no reator só foi positiva quando realizada com água de abastecimento, tendo o reator entrado em colapso quando a recirculação foi realizada com o efluente tratado.
The main objective of this work was to evaluate the sulfate removal from acid mine drainage in two types of anaerobic reactors, one with a granular sludge (UASB) and another with immobilized biomass (HAIB reactor). Previous published studies have showed positive results for the anaerobic treatment of acid mine drainage, however, in most of them, it was applied a pre-treatment operation. This study evaluated the operation of anaerobic reactors without pre-treatment of the acid mine drainage under different parameters. The parameters COD/\'SO IND.4\'POT.2-\' ratio, correction of affluent pH, sulfate loading and recirculation of the liquid phase were tested for horizontal-flow anaerobic immobilized biomass (HAIB) reactor. The results showed that the decrease in the sulfate loading was a determining factor for the successful sulfate removal found throughout the operation of the reactors. The COD/\'SO IND.4\'POT.2-\' ratio was also important and the removal efficiency of sulfate reached levels above 70% with a small accumulation of acetic acid in the effluent when using stoichiometric ratio of 0.67. For the operation of the upflow anaerobic sludge blanket (UASB) reactor, the parameters were the volume of the sludge blanket, the COD/\'SO IND.4\'POT.2-\' ratio, the sulfate loading and the recirculation of the liquid phase. Similarly ti the HAIB reactor, reducing the sulfate load was essential for obtaining better results. The COD/\'SO IND.4\'POT.2-\' ratio of 1.0 showed a improved sulfate removal efficiency for the UASB reactor when compared to stoichiometric ratio at 0.67 ant the recirculation in this reactor was only positive when carried out with tap water. The UASB reactor collapsed when recirculation was carried out whit the treated effluent.
The main objective of this work was to evaluate the sulfate removal from acid mine drainage in two types of anaerobic reactors, one with a granular sludge (UASB) and another with immobilized biomass (HAIB reactor). Previous published studies have showed positive results for the anaerobic treatment of acid mine drainage, however, in most of them, it was applied a pre-treatment operation. This study evaluated the operation of anaerobic reactors without pre-treatment of the acid mine drainage under different parameters. The parameters COD/\'SO IND.4\'POT.2-\' ratio, correction of affluent pH, sulfate loading and recirculation of the liquid phase were tested for horizontal-flow anaerobic immobilized biomass (HAIB) reactor. The results showed that the decrease in the sulfate loading was a determining factor for the successful sulfate removal found throughout the operation of the reactors. The COD/\'SO IND.4\'POT.2-\' ratio was also important and the removal efficiency of sulfate reached levels above 70% with a small accumulation of acetic acid in the effluent when using stoichiometric ratio of 0.67. For the operation of the upflow anaerobic sludge blanket (UASB) reactor, the parameters were the volume of the sludge blanket, the COD/\'SO IND.4\'POT.2-\' ratio, the sulfate loading and the recirculation of the liquid phase. Similarly ti the HAIB reactor, reducing the sulfate load was essential for obtaining better results. The COD/\'SO IND.4\'POT.2-\' ratio of 1.0 showed a improved sulfate removal efficiency for the UASB reactor when compared to stoichiometric ratio at 0.67 ant the recirculation in this reactor was only positive when carried out with tap water. The UASB reactor collapsed when recirculation was carried out whit the treated effluent.
Palavras-chave
Sulfato, Recirculação, Reator UASB, RAHLF, Drenagem ácida de minas, Carga de sulfato aplicada, HAIB reactor, COD/'SO IND.4'POT.-2' ratio, Recirculation, Sulfate, Sulfate load, Acid mine drainage