DEFAR - Artigos publicados em periódicos
URI permanente para esta coleçãohttp://www.hml.repositorio.ufop.br/handle/123456789/531
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Item Simultaneous removal of sulfate and arsenic using immobilized nontraditional SRB mixed culture and alternative low-cost carbon sources.(2017) Matos, Letícia Paiva de; Costa, Patrícia Freitas; More, Mariana; Gomes, Paula Cristine Silva; Silva, Silvana de Queiroz; Gurgel, Leandro Vinícius Alves; Teixeira, Mônica CristinaThis study was designed to obtain simultaneous sulfate (SO4 2−) and As(III) ions removal by non-traditional sulfate-reducing bacteria (SRB) growing in the presence of a protein biomass (PCF), a solid residual material produced by the poultry industry. Microbial cells and PCF were immobilized into calcium alginate beads to reduce mass losses. Microbial consortium efficiency was tested under different operational conditions: sodium lactate, glycerol and PCF as carbon sources; increasing As(III) content; acidic pH (5.0). Microbial diversity was evaluated by PCR-DGGE. Pantoea agglomerans, Enterobacter sp., Citrobacter sp., Cupriavidus metallidurans, Ralstonia sp. and Burkholderia cepacia were found. With the aim to obtain SO4 2− and As(III) simultaneous removal, three semi-continuous up-flow reactors were constructed and operated for more than 100 days to prove their feasibility and reliability. Both SO4 2− and As(III) ions were removed with 74.8% and 80% efficiency, respectively. Solid products were characterized by SEM-EDX, confirming PCF and non-traditional SRB roles during arsenic immobilization. Arsenic/sulfur compounds (possibly As/sulfides) were produced by reaction between As(III) and biogenic sulfide. Microbial consortium proved its ability of growing in an acidic environment without losing its sulfate reductive capacity by using glycerol and PCF as alternative carbon sources and tap water as micronutrients source. The non-traditional SRB culture removed both SO4 2− and As(III) ions simultaneously, with no prior step needed to guarantee As(III) oxidation to As(V). Two different mechanisms could be involved: (i) precipitation as arsenic sulfide or, (ii) adsorption onto PCF/cells calcium alginate beads.Item Nickel, manganese and copper removal by a mixed consortium of sulfate reducing bacteria at a high COD/sulfate ratio.(2014) Barbosa, Leonardo de Paiva; Costa, Patrícia Freitas; Bertolino, Sueli Moura; Silva, Júlio César Cardoso da; Cota, Renata Guerra de Sá; Leão, Versiane Albis; Teixeira, Mônica CristinaThe use of sulfate-reducing bacteria (SRB) in passive treatments of acidic effluents containing heavy metals has become an attractive alternative biotechnology. Treatment efficiency may be linked with the effluent conditions (pH and metal concentration) and also to the amount and nature of the organic substrate. Variations on organic substrate and sulfate ratios clearly interfere with the biological removal of this ion by mixed cultures of SRB. This study aimed to cultivate a mixed culture of SRB using different lactate concentrations at pH 7.0 in the presence of Ni, Mn and Cu. The highest sulfate removal efficiency obtained was 98 %, at a COD/sulfate ratio of 2.0. The organic acid analyses indicated an acetate accumulation as a consequence of lactate degradation. Different concentrations of metals were added to the system at neutral pH conditions. Cell proliferation and sulfate consumption in the presence of nickel (4, 20 and 50 mg l-1), manganese (1.5, 10 and 25 mg l-1) and copper (1.5, 10 and 25 mg l-1) were measured. The presence of metals interfered in the sulfate biological removal however the concentration of sulfide produced was high enough to remove over 90 % of the metals in the environment. The molecular characterization of the bacterial consortium based on dsrB gene sequencing indicated the presence of Desulfovibrio desulfuricans, Desulfomonas pigra and Desulfobulbus sp. The results here presented indicate that this SRB culture may be employed for mine effluent bioremediation due to its potential for removing sulfate and metals, simultaneously.Item Bioremoval of arsenite and sulfate by a mixed culture with sulfate-reducing capacity growing on powdered chicken feathers.(2014) Costa, Patrícia Freitas; Matos, Letícia Paiva de; Leão, Versiane Albis; Teixeira, Mônica CristinaA relatively unusual and low-cost waste material was investigated for As(III) and SO4 2_ removal by a mixed culture containing sulfate-reducing bacteria (SRB). Powdered chicken feathers (PCF) were tested as an organic nutrient source for SRB growth and also as solid support for As(III) immobilization. PCF’s efficiency as a growth substrate was compared with that of sodiumlactate, used as a positive control. As(III) removal increased, from 38% (in the presence of sodium lactate only) to 80%, in the presence of PCF and sodium lactate together. The soluble organic part of PCF contained 2302 mg L_1 of carbon, suggesting the possibility of using PCF as an electron donor for SRB growth. When PCF was the only carbon source, the achieved sulfate removal was lower (13.4%) than that observed when PCF and lactate were added to the medium (27.0%), but higher than those obtained when only lactate was employed at COD/sulfate ratios of 0.67 or1. Arsenicremoval increasedfrom38%(lactate,COD/sulfate = 0.67) to80%inthe presence ofPCFand lactate. The results suggest an alternative biological route for arsenite removal which does not require the use of a strong oxidizing agent to promote As(III) oxidation to As(V) before its removal.