Clean environmental strategy applied to anatomy laboratory wastewater purification: a hybrid and integrated performance of a photo-electro-Fered-Fenton process

Abstract

Formaldehyde (CH₂O) is an important preservative of anatomic pieces in laboratories; Solutions with high concentrations of CH₂O are used to avoid the deterioration of anatomic pieces. Besides the high concentration of CH₂O, organic content may leachate from the material stored in the tanks, increasing the complexity of the wastewater generated. The anatomy laboratory wastewater with high formaldehyde concentration (ALW-CFA) presents potential toxic effects to humans and the ecosystem in general, for this reason, proper treatment is demanded before its discharge. In the present work, the degradation of CH₂O and reduction of toxicity levels of ALW-CFA samples were studied through the application of the process photo-electro-Fered-Fenton process (PEF-Fered). The suitable operational conditions of the process PEF-Fered such as initial solution pH, current intensity, and H₂O₂ initial concentration, were studied by the application of an RSM evaluating the reduction of concentrations of CH₂O and TOC. Then, the increment of O₃ to the PEF-Fered process was performed (PEF-Fered-O₃), aiming to increase the oxidative potential of the system. However, it was observed that the use of many oxidative inputs at the same time (hybrid process) was not interesting for the ALW-CFA degradation, thus, the best treatment strategy which provided a lower toxicity level (LC_{50 %}= 56.94) was the AO followed by H₂O₂ and O₃, with a removal of 90 % of CH₂O and 85 % of TOC, under the following operational conditions, solution pH 4.5; the current intensity of 2.4 and H₂O₂ concentration of 24,000 mg l^-1. With the application of the advanced combined treatment, the pollution potential of this wastewater was reduced, evidencing the protection of human health and ecosystems in general.