Enhanced solar photo-electro-Fenton by Theobroma grandiflorum addition during pharmaceuticals elimination in municipal wastewater: Action routes, process improvement, and biodegradability of the treated water

Abstract

This work shows, for the first time, the use of the autochthonous Amazonian fruit copoazu (COPE, Theobroma grandiflorum) as an enhancer of the solar photoelectroFenton (SPEF) performance. SPEF, using a BDD anode with Na2SO4 or IrO2 anode in NaCl and actual sunlight, was applied to degrade four representative pharmaceuticals (acetaminophen, diclofenac, ciprofloxacin, and sulfamethoxazole) simultaneously in raw municipal wastewater (MWW). The effect of COPE addition on both pharmaceuticals degradation and keeping iron in solution at near-neutral pH is presented. In the SPEF process based on IrO2-NaCl, electrogenerated reactive chlorine species played the main degrading role. Meanwhile, in the BDD-based process, hydroxyl radical and photolysis were the main agents responsible for the elimination of pharmaceuticals. The two SPEF processes, IrO2-NaCl and BDD-Na2SO4, led to ~99 and ~49% of pondered degradation of pharmaceuticals, respectively. The addition of an extract of copoazu to the reactor equipped with the BDD anode improved the elimination, achieving ~70% of pondered removal of the pharmaceuticals. COPE acted as a natural complexing agent, favoring the catalytic cycle of iron in the system. Finally, the biodegradability (using aerobic microorganisms) of the MWW treated by the improved SPEF (with the BDD anode) was tested. It was found that the microorganisms were able to remove up to 54.6% of the organic carbon content in the sample, indicating the high biocompatibility of water resultant from the treatment by the SPEF improved with the copoazu presence.