The ZVI-Fenton process affects the total load of human pathogenic bacteria in wastewater samples

We investigated the performance of a heterogeneous Fenton-like reaction (ZVI-Fenton, i.e., ZVI + H2O2, where ZVI = zero-valent iron) towards the removal of potentially pathogenic bacteria in wastewater (WW). The effectiveness of the process was investigated towards live bacteria (measured by flow cytometry) as well as potentially pathogenic bacteria (identified by 16S rRNA amplicon sequencing), antibiotic resistance genes and class 1 integrons (assessed by qPCR). The ZVI-Fenton process resulted about as effective as H2O2 alone to decrease live bacteria (p > 0.05), if compared with the blank controls (neither ZVI nor H2O2, p = 0.00005), although it did not reduce the relative abundance of the tested antibiotic resistance genes or class 1 integrons (p > 0.05). However, ZVI-Fenton was quite effective in lowering the total content of the potentially pathogenic bacteria in WW when compared to the controls with H2O2 (p = 0.0186) and without H2O2 (p = 0.0252). These findings suggest that ZVI-Fenton has potential as an effective WW treatment technique that should be further investigated for future application in WWTPs.