DEFAR - Departamento de Farmácia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/530
Navegar
4 resultados
Resultados da Pesquisa
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 A sulfate-reducing bacterium with unusual growing capacity in moderately acidic conditions.(2007) Rampinelli, Letícia Roni; Azevedo, Roberta D'Angelo; Cota, Renata Guerra de Sá; Leão, Versiane Albis; Teixeira, Mônica CristinaThe use of sulfate-reducing bacteria (SRB) is a cost-effective route to treat sulfate- contaminated waters and precipitate metals. The isolation and characterization of a SRB strain from an AMD in a Brazilian tropical region site was carried out. With a moderately acidic pH (5.5), the C.1 strain began its growth and with continued growth, modified the pH accordingly. The strain under these conditions reduced sulfate at the same rate as an experiment performed using an initial pH of 7.0. The dsrB gene-based molecular approach was used for the characterization of this strain and its phylogenetic affiliation was similar to genus Desulfovibrio sp. The results show an SRB isolate with unexpected sulfate reducing capacity in moderately acidic conditions, bringing new possibilities for the treatment of AMD, as acid water would be neutralized to a mildly acidic condition.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.Item Specific growth rate of sulfate reducing bacteria in the presence of manganese and cadmium.(2006) Medírcio, Silvia Nicolato; Leão, Versiane Albis; Teixeira, Mônica CristinaThe development of technologies based on the use of sulfate-reducing bacteria (SRB) to treat sulfate contaminated wastewaters has produced a cost-effective route to precipitate metals. In this work the effects of cadmium and manganese in the SRB growth rates were assessed. It was observed that duplication time is 50 h in the presence of cadmium and 6 h in the presence of manganese, thus showing that the SRB growth rate was more affected by the presence of cadmium. A low sulfate reduction (maximum 25%) occurred which was sufficient for metal precipitation. The results are discussed considering their implications for metal precipitation in acid mining drainage.