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

PAISIO CE; M.A.TALANO; ANGELINI VA; AGOSTINI E

Buenos Aire

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

SETAC

Phenol constitutes oneof the main sources of aquatic ecosystem contamination. Therefore, it isimportant to treat phenol contaminated solutions and effluents before theirrelease to the environment. We have previously demonstrated that two nativebacterial strains isolated from polluted sites, Acinetobacter tandoii RTE1.4and Rhodococcus sp. CS1, were capable of removing this contaminant with highefficiency. However, the disappearance of a pollutant from a solution notalways implies detoxification. Thus, the aim of the present work was todetermine the toxicity of the remaining post-removal solutions (PRS) after abioremediation process, using tests with organisms of different trophic levels.Phenol solutions initially containing 200 and 600 mg/L or 200 and 1000 mg/L ofthe pollutant were treated with A. tandoii sp. RTE1.4 and Rhodococcus sp. CS1,respectively. Then, PRS derived from these treated solutions, were analyzedusing AMPHITOX, Microtox® and Lactuca sativa test. The toxicity of controlsolutions, such as culture media without phenol and culture media supplementedwith phenol (without inoculation) was also evaluated. All the assayed phenolsolutions, without bacterial treatment, were highly toxic for the testedorganisms. Contrarily, the toxicity of PRS varied depending on the testemployed, however it was generally observed that bacterial treatmentssignificantly reduced the toxicity of solutions supplemented with phenol. Atoxicity reduction of PRS was detected using Microtox®, compared with untreatedphenol solutions, while with AMPHITOX and Lactuca sativa, PRS showedsignificant toxicity even after bacterial treatment. We suggest that it wouldbe due to the high salinity of the culture media in which the reaction tookplace, and this effect could be reduced by water addition. Thus, as analternative strategy, PRS were diluted and the toxicity of these samples wassignificantly reduced. This is a practice usually applied in plants fortreating industrial effluents and represents a simple method for reducing thetoxicity of PRS. This study showed that phenol removal process, using A.tandoii RTE1.4 and Rhodococcus sp. CS1, was useful to bioremediate solutionscontaining high phenol concentrations since the toxicity of PRS wassignificantly reduced.