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Highlights Saccharomyces cerevisiae showed 76% Cu(II) removal efficiency. The biosorption process was adjusted to the Langmuir isotherm. The yeast presented maximum biosorption capacity of 4.73 mg g −1 . The analyzed variables influence the biosorption process.

A biorremediação é uma alternativa atraente para o tratamento de solos contaminados com hidrocarbonetos de petróleo. No entanto, a efetividade do processo pode ser limitada não só pelas características do contaminante, mas também pela sua biodisponibilidade. Este trabalho tem como meta o estabelecimento de procedimento preliminar para identificar o fator principal (recalcitrância ou biodisponibilidade) que interfere negativamente na biodegradação, resultando em baixas eficiên-cias. Foram realizados testes em microcosmos contendo solo aplicando as técnicas de bioestímulo e bioaumento. Experimentos semelhantes foram conduzidos em meio líquido contendo óleo cru e microorganismos extraídos do solo contaminado, nutrientes e inóculo microbiano (Rhodoturula glutinis e Nocardia nova). Após 30 dias, o maior nível de biodegradação (98.8%) foi obtido na condição com bioaumento em meio líquido, indicando que o problema principal de biodegradação de hidrocarbonetos de petróleo pode estar associado à baixa biodisponibilidade destes no solo e não apenas a recalcitrância intrínseca do poluente residual.Bioremediation is an attractive alternative to treat soils contaminated with petroleum hydrocarbons. However, the effectiveness of biodegradation process can be limited by both contaminant characteristics and its bioavailability in soil. This work aims at establishing a preliminary procedure to identify the main factor (hydrocarbon recalcitrance or its bioavailability) that impairs the biodegradation, possibly resulting in low remediation efficiencies. Tests in soil microcosms were carried out applying biostimulation and bioaugmentation techniques. Similar experiments were conducted using liquid medium containing crude oil and microorganisms, both of them extracted from a weathered contaminated soil sample, nutrients and microbial inoculum constituted of Rhodoturula glutinis and Nocardia nova. After 30 days, highest microcosms biodegradation levels (98.8%) were obtained with bioaugmentation in liquid medium, pointing out that the main problem of petroleum hydrocarbon utilization by microorganisms was associated to its availability and not only to the intrinsic recalcitrancy of remaining pollutants.

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Bioremediation processes are being applied nowadays for treatment of contaminated soils by petroleum products. However, only chemical analyses are used for efficiency verification, without taking into account a biological indicator. The aim of this work was the application of two ecotoxicological tests for the evaluation of a soil contaminated by crude oil, after treatment on a bioreactor, in different conditions. Sample A was treated with biostimulation (pH, nutrients and moisture control), while samples B and C, besides biostimulation was applied bulking material (sawdust; 10% w/w) also. The ecotoxicological tests chosen were luminescent bacteria Vibrio fischeri (ISO 11348-3:1998) and an avoidance behavior test with Eisenia fetida earthworms (still in a draft form). This test consists in the exposition of the organisms to contaminated soil and control soil samples, simultaneously, to evaluate the percentage of organisms that goes from the center of the recipient to the control sample sector. The results of avoidance behavior tests of samples A, B and C were, respectively, 52%, 29% and 50%. Those results indicate no toxicity, once the criteria for a sample be considered toxic is that more than 80% of the total exposed organisms are in the control soil at the end of the test. However, the test with Vibrio fischeri indicated toxicity for sample B (CE 50 13.8%), probably because of the recent contamination. Those results indicate that, although the importance of ecotoxicological tests inclusion for the complementation of bioremediation processes evaluation, at least two tests, using different organisms must be performed for a better consideration.