Abstract This study shows the results obtained of evaluation and comparison of chemical analysis and ecotoxicity for evaluated the quality of water contaminated with gasoline after Fenton process. The process Fenton was efficient to remove the aromatics organic compounds such as benzene, toluene and xylenes from water contaminated with gasoline. At 90 minutes of reaction time, the concentration measured of aromatics compounds by gas chromatography were less than limit of quantification (0.05mg L-1). This value is in accordance with the limits established by Brazilian legislation for the effluents discharge. On the other hand, analysis of total phenols and dissolved organic carbon demonstrated at 120 minutes that all dissolved organic compound and total phenols are not totally removed even though benzene, toluene and xylenes were almost completely removed. Phytotoxicity tests using Sinapis alba as biological response showed that water contaminated with gasoline are not toxic, however these results was probably influenced by volatilization of aromatics compounds during the assay. Differently, the ecotoxicity using Daphnia magna showed that water contaminated with aromatic compounds is toxic, but after 120 minutes of treatment the toxicity was reduced more than 50%. Then, Daphnia magna was the better bioindicator to evaluate the efficiency of Fenton process since these results were according with response of dissolved organic carbon and total phenol showing the toxicity of intermediates produced during the Fenton process.

In this work the potentiality of photo-Fenton processes were investigated toward the degradation of aromatic hydrocarbons (BTXs) from water contaminated with gasoline. The main results demonstrated that BTXs can be quickly degraded by photo-Fenton process assisted by solar or artificial UV-A radiation, degradation that leads to generation of characteristic phenolic transient species (ie. phenol, hydroquinone and catechol). In the treatment of contaminated water by photo-Fenton processes assisted by solar light, complete BTXs removal was observed in reaction times of about 5 min. Mineralization of about 90% was also observed by applying a multiple H2O2 addition system.

In this study the efficiency of advanced oxidative processes (AOPs) were investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX). The results indicated that BTX can be effectively oxidized by the UV-A-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolyc intermediates at reaction times of about 30 min. Preliminary investigations using solar light suggest a good potentiality of the process for the treatment of large volumes of aqueous samples containing these polluting species.

After decades of polluting actions the environment manifests serious and global consequences. The contamination of soils and groundwater by organic compounds is a widespread problem mainly on account of contamination by leakage from underground storage tanks, which often results in the release of gasoline or other chemicals. The main problem about groundwater contamination is due to the toxicity of water-soluble components such as benzene, toluene and xylene (BTX). In the present work a study about classical and modern methods for remediation of BTX is reported.