Two birds with one stone: Degradation of pharmaceuticals and elimination of bacteria upon treatment of urban wastewater with a Fenton-like process, based on zero-valent iron at pH 4.

Abstract

ZVI-Fenton, which is the combination of zero-valent iron (metallic Fe) and H₂O₂ is a relatively cheap advanced oxidation process for the elimination of contaminants from wastewater. Here we experimentally tested the ZVI-Fenton reaction at pH 4 towards two crucial goals in the treatment of secondary (partially treated) urban wastewater: (i) degradation of pharmaceuticals such as anti-inflammatory drugs (ibuprofen) and antibiotics (cefazolin, sulfamethoxazole), and (ii) elimination of a considerable fraction of bacteria through a combination of acidic pH and strongly oxidising conditions. In detail, ZVI-Fenton at pH 4 achieved degradation of both primary contaminants and potentially problematic transformation intermediates. The latter include toxic 4-isobutylacetophenone from ibuprofen and compounds potentially retaining antibiotic properties, namely cefazolin products with an intact β-lactam ring and sulfamethoxazole products retaining the p-amino sulfonic acid moiety. Furthermore, the ZVI-Fenton process significantly lowered the total abundance of bacteria, greatly aiding the final disinfection stage. Overall, both objectives were successfully achieved demonstrating that ZVI-Fenton at pH 4 is an efficient treatment against chemical and microbiological contaminants.