New hybrid strategy of the photo-Fered-Fenton process assisted by O for the degradation of wastewater from the pretreatment of biodiesel production.

The present work aims to fill a scientific gap regarding the treatment of wastewater from the enzymatic pretreatment of biodiesel production (WEPBP), as well as the identification of organic contaminants present in this complex matrix. Different treatment strategies were proposed for the removal of total organic carbon (TOC) and chemical oxygen demand (COD) from WEPBP. The interesting combination of O/HO/UV-Vis and electrocoagulation (EC) process was studied in two setups, with the EC process applied prior to O/HO/UV-Vis and vice versa. Further, the innovative hybrid system based on the photo-Fered-Fenton process with O addition (PEF-Fere-O) was preliminarily studied for WEPBP treatment. The hybrid system provided the best results for the WEPBP treatment when the reactor was operated at pH of 4.5, 65 mg O L and 10000 mg HO L, UV-Vis was used as the irradiation source, and the current intensity of 3.0 A. Removals of 45% of TOC and 68.7% of COD were reached within 45 min. Oleic acid, linoleic acid, and Diisooctyl phthalate (DIOP) were the main organic contaminants identified in the WEPBP as determined by Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Acute toxicity assays with the bio indicator Artemia salina were carried out in untreated and treated WEPBP samples, indicating that the PEF-Fere-O treatment decreased the amount of contaminants present in the WEPBP as well as reduced the toxicity levels and increased biodegradability index, suggesting its great potential for the treatment of complex industrial wastewaters.