Ecotoxicological evaluation of oil wastewaters treated by solar photochemical oxidation with Poecilia reticulata

Abstract

The purpose of this work is to carry out an ecotoxicological evaluation of an aqueous effluent from Petróleos de Venezuela S.A. (PDVSA) treated with solar photochemical advanced oxidation (AOP) processes (photoFenton-like and Photocatalysis combined). The water sample was characterized through measurements such as: pH, conductivity, Chemical Oxygen Demand (COD); total petroleum hydrocarbons (TPH), sulfur, sulfates and Ion Chromatography (IC) for other ions. Subsequently, the organic species and ions present in the sample were identified by Mass Coupled Gas Chromatography (GC-MS). A simulation was carried out in the laboratory of the conditions of the activated sludge bioreactor of a wastewater treatment plant. Static ecotoxicological tests with Poecilia reticulata were carried out taking into account the USEPA OPPTS 850.1075 (1996) standard. As results it was obtained that when applying the AOPs with solar radiation, a reduction of 88.95% of the COD and 100% for the TPH and a conversion of sulfide to sulfate of 96.95% was observed. The simulation of the bioreactor in the laboratory yielded yield values of 88.89% and the ecotoxicological test yielded an LC50 of 0.26%. The combination of AOPs and biological oxidation reduced organic matter by 98.77% with a non-calculable LC50. Therefore, it is concluded that with the combination of AOP and biological oxidation techniques, innocuous effluents are obtained for the aquatic organisms of the surrounding ecosystem.