No abstract

This study evaluated the use of commercial rhamnolipid biosurfactant supplementation in the phytoremediation of a soil via sunflower (Helianthus annuus L.) cultivation. The soil, obtained from an industrial area, was co-contaminated with heavy metals and petroleum hydrocarbons. The remediation tests were monitored for 90 days. The best results for removal of contaminants were obtained from the tests in which the sunflower plants were cultivated in soil with 4 mg kg of the rhamnolipid. Under these conditions, reductions of 58% and 48% were obtained in the total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbon (PAH) concentrations, respectively; reductions in the concentrations of the following metals were also achieved: Ni (41%), Cr (30%), Pb (29%), and Zn (20%). The PCR-DGGE analysis of soil samples collected before and after the treatments verified that the plant cultivation and biosurfactants supplementation had little effect on the structure of the dominant bacterial community in the soil. The results indicated that sunflower cultivation with the addition of a biosurfactant is a viable and efficient technology to treat soils co-contaminated with heavy metals and petroleum hydrocarbons.

RESUMOEstudos sobre a contaminação de solos e seus mecanismos são cada vez mais explorados devido a necessidade de segurança a longo prazo exigida para sistemas de contenção de resíduos. Neste sentido, investigou-se o acúmulo de alguns metais pesados, a capacidade de impermeabilização do solo imediatamente abaixo de uma célula do Aterro de Resíduos Sólidos da Muribeca, e as características físico-químicas do percolado. Os perfis de concentração dos metais pesados e de sólidos voláteis no solo mostraram que existe uma frente de contaminação em direção ao fundo, evidenciando-se também que ocorre ampla faixa de concentração dos metais analisados, relacionada à concentração de cada espécie no percolado. O Chumbo, o Cobre e o Manganês foram os metais preferencialmente sorvidos e apresentaram uma velocidade média de frente de saturação de 2,3 x 10 -2 m/ano, que indica transporte por advectivo-dispersivo, em desacordo com a textura do solo. PALAVRAS-CHAVE:Contaminação, solo, metais pesados, resíduos sólidos urbanos. ABSTRACT INTRODUÇÃOA disposição inadequada de resídu-os no solo e nas águas superficiais é reconhecida como um dos graves problemas da atualidade. Os efeitos do lançamento de rejeitos na natureza são incalculáveis e recaem principalmente na escassez, na contaminação da água, e no aumento das doenças associadas à poluição ambiental. Entre as técnicas para tratamento e disposição final de resíduos sólidos urbanos (RSU), aterros controlados e aterros sanitários, estão entre as que apresentam menor relação de custo, especialmente quando se dispõe de áreas apropriadas. Nestes processos de disposição final, ocorre a decomposição do material originalmente disposto devido à ação da microbiota nativa, tanto em aerobiose, que ocorre nas regiões mais superficiais das células de confinamento, quanto em anaerobiose, estabelecida nas regiões mais profundas. Como produto da biodeterioração dos resíduos e somado à água infiltrada nas células, forma-se o líquido chamado de chorume ou percolado. As características físico-químicas e microbiológicas do percolado são função da composição, origem e idade dos resíduos originalmente dispostos, bem como da fase de decomposição do processo. De forma geral, este líquido contém, em concentrações variadas, compostos orgânicos polares, apolares, além de metais pesados que podem contaminar o meio ambiente e ser tóxicos aos seres vivos (Palmisano & Barlaz, 1996;Yasuhara et al., 1997).Sistemas de impermeabilização são requeridos para a confecção de aterros de RSU devido ao elevado potencial poluente do percolado, e ao fato de minimizarem Vol. 9 -Nº 3 -jul/set 2004,211-217

The aim of this work was to optimize the bioremediation of crude oil-contaminated sand sediment through the biostimulation technique. The soil was obtained in the mid-tide zone of Guanabara Bay, Rio de Janeiro, Brazil and was artificially contaminated with crude oil at 14 g kg(-1). Bioremediation optimization was performed using an experimental design and statistical analysis of the following factors: supplementation with commercial biosurfactant Jeneil IBR 425 and commercial mineral NPK fertilizer. The response variable used was the biodegradation of the heavy oil fraction, HOF. The analysis of the studied factors and their interactions was executed using contour plots, Pareto diagram and ANOVA table. Experimental design results indicated that the supplementation with fertilizer at 100:25:25 C/N/P ratio and biosurfactant at 2 g kg(-1) yielded biodegradation of HOF at about 30% during 30 days of process. Some experiments were carried out using the experimental design results, yielding 65% of biodegradation of HOF and 100% of n- alkanes between C15 and C30 during 60 process days. Intrinsic biodegradation test was carried out, yielding 85% of biodegradation of n-alkanes between C15 and C30 during 30 days of process.

Environmental and economic concerns accelerated biofuels research and industrial production. Many countries have been using diesel and biodiesel blends as fuels justifying research on biofilms formation and metals corrosion. Cylinders made of AISI-1020 carbon steel with an exposed area of 1587 mm2, water, and water associated with B3 fuel (diesel/biodiesel blend at 97 : 3 v/v) were used.The formation of biofilms was detected, and biocorrosion was detected on AISI-1020. The results showed a variation in sessile microflora during the experiments. In the biofilms, a significant concentration of aerobic, anaerobic, IOB,Pseudomonas aeruginosa, and sulfate-reducing bacteria was observed. The corrosion rates varied between0.45±0.01and0.12±0.01 mm/year, depending on the experimental conditions. The main corrosion products identified were various forms of FeOOH, magnetite, and all forms of FexSy. In systems where there were high levels of sulfate reducing bacteria, corrosion pits were observed. In addition, the aliphatic hydrocarbons present in the fluid containing 10% B3 were totally degraded.