Evaluation of phenol bioremediation process by two native bacterial strains using different toxicity test

? C.E. PAISIO, ; M.A. TALANO,; V.A. ANGELINI,; E. AGOSTINI.

BsAs

Congreso; 11th SETAC Latin America Biennial Meeting; 2015

Phenol constitutes one of the main sources of aquatic ecosystem contamination. Therefore, it is important to treat phenol contaminated solutions and effluents before their release to the environment. We have previously demonstrated that two native bacterial strains isolated from polluted sites, Acinetobacter tandoii RTE1.4 and Rhodococcus sp. CS1, were capable of removing this contaminant with high efficiency. However, the disappearance of a pollutant from a solution not always implies detoxification. Thus, the aim of the present work was to determine the toxicity of the remaining post-removal solutions (PRS) after a bioremediation process, using tests with organisms of different trophic levels.Phenol solutions initially containing 200 and 600 mg/L or 200 and 1000 mg/L of the pollutant were treated with A. tandoii sp. RTE1.4 and Rhodococcus sp. CS1, respectively. Then, PRS derived from these treated solutions, were analyzed using AMPHITOX, Microtox® and Lactuca sativa test. The toxicity of control solutions, such as culture media without phenol and culture media supplemented with phenol (without inoculation) was also evaluated. All the assayed phenol solutions, without bacterial treatment, were highly toxic for the tested organisms. Contrarily, the toxicity of PRS varied depending on the test employed, however it was generally observed that bacterial treatments significantly reduced the toxicity of solutions supplemented with phenol. A toxicity reduction of PRS was detected using Microtox®, compared with untreated phenol solutions, while with AMPHITOX and Lactuca sativa, PRS showed significant toxicity even after bacterial treatment. We suggest that it would be due to the high salinity of the culture media in which the reaction took place, and this effect could be reduced by water addition. Thus, as an alternative strategy, PRS were diluted and the toxicity of these samples was significantly reduced. This is a practice usually applied in plants for treating industrial effluents and represents a simple method for reducing the toxicity of PRS.This study showed that phenol removal process, using A. tandoii RTE1.4 and Rhodococcus sp. CS1, was useful to bioremediate solutions containing high phenol concentrations since the toxicity of PRS was significantly reduced.