Mitigation of the negative impacts of 84 disinfectant exposure for phenol treatment by an electro-enhanced SBR: Performance, oxidative stress, iron homeostasis and antibiotic resistance genes

A huge application of 84 disinfectant, a commercial disinfection product, attracts widely concerns as the primary recipients of 84 disinfectant are wastewater treatment plants (WWTPs). However, the impacts of 84 disinfectant on WWTPs and corresponding mitigation strategies remain unclear. Herein, we systematically investigated the effects of 84 disinfectant on the phenol treatment performance and microbial oxidative stress responses in control sequencing batch reactor (SBR) and electro-enhanced SBR (E-SBR). At a low concentration, the 84 disinfectant had no impact on the phenol treatment performance in both SBR and E-SBR. At higher concentrations, the 84 disinfectant significantly inhibited the phenol treatment performance in SBR, while the electrical stimulation in E-SBR significantly alleviated these negative impacts. Electrical stimulation alleviates the detrimental impacts on key enzymes involved in phenol degradation; it activates the antioxidant system, repressing the generation of reactive oxygen species. Electrical stimulation also inhibits the DNA repair system response, reduces cell membrane permeability, enhances cell membrane integrity, and maintains iron homeostasis by activating the ferric uptake regulator (Fur), ultimately reduces the total abundance of antibiotic resistance genes (ARGs) by changing their host bacteria.