RESUMO
The use of biosurfactants in bioremediation of hydrocarbons and in the removal of heavy metals in crude oils is considered an attractive subject. The vanadium pollution in soil and sediments had attracted research interest in exploring eco-friendly methods of remediation. The present study was conducted to evaluate the potential of a biosurfactant to remove vanadium from artificially contaminated sand. The biosurfactant producer's strain selection process was carried out from 23 strains in two steps. In the primary screening, four preliminary tests were carried out: the emulsification index (24 and 72 h), the surface tension, and the rate of bacterial adhesion to hydrocarbons. In the secondary screening, the surface tension and rhamnolipids concentration were determined, also critical micellar concentration and dilution were calculated. The RNA 16s of selected strain was sequence and the strain was identified as Pseudomonas sp. By chromatographic and spectroscopic assays, the structure of the rhamnolipids was determined. The maximal vanadium removal efficiency (85.5%) was achieved with a rhamnolipids' concentration of 240 mg l-1. The vanadium concentration was determined by spectroscopic technique. Rhamnolipids produced by this strain can potentially be used in the removal of vanadium.
Assuntos
Poluentes do Solo , Vanádio , Biodegradação Ambiental , Glicolipídeos , TensoativosRESUMO
The creation of pit lakes is usually an acceptable solution from the landscaping point of view for voids left by discontinued open-pit mines. However, without rehabilitation, these voids represent a potential environmental risk. The aim of the present work was to assess, for the first time, the water quality, i.e., physicochemical characteristics, metal and metalloid (MM) content, and ecotoxicity of the waters of the El Cobre Blue Lagoon, a pit lake formed in an open-pit copper mine in Cuba. Potential effects of rainy season vs. dry season and spatial location (different depths) on water characteristics were considered. Results revealed that water contained was moderately acidic (pH = 4.6 ± 0.2), with high electrical conductivity (EC = 3.02 ± 0.03 mS cm-1), whatever the season. Dissolved oxygen (DO = 9.9 ± 2.0 mg L-1), total dissolved solid (TDS = 7003 ± 245 mg L-1), and sulfate concentration (6556 ± 1410 mg L-1) in the El Cobre Blue Lagoon water were above acceptable limits for sources of surface water as recommended by Cuban standard (NC 1021:2014). High copper (43.6 ± 1.7 mg L-1) and manganese (24.1 ± 1.1 mg L-1) contents were detected. Except for EC, sulfates, chlorides, TDS, nitrates, and phosphates, other physicochemical parameters were stable between dry and rainy seasons (p < 0.05). El Cobre Blue Lagoon waters showed an ecotoxicological impact on Vibrio fischeri. No significant differences were detected between all sampling points in the lake for each parameter monitored for a given time. These first results show the spatial homogeneity but poor quality of waters from El Cobre Blue Lagoon. Remediation processes need to be implemented in order to lessen the human and environmental health risk and favor potential water reuse. We suggest the use of constructed wetlands for water treatment. This preliminary research work can serve to alert Cuban local public authorities to the need to rehabilitate such sites.