Effect of magnetic nanoparticles and silver-loaded magnetic nanoparticles on advanced wastewater treatment and disinfection

Strict discharge standards necessitate the advanced treatment and disinfection of wastewater treatment plant (WWTP) effluents for environmental protection and water reuse purposes. This study aimed to apply magnetic nanoparticles (MNPs) and silver-loaded magnetic nanoparticles (Ag-MNPs) in the advanced treatment and disinfection of the secondary effluent from a municipal WWTP. The as-prepared nanoparticles were employed under various conditions of nanoparticle dose, contact time, and effluent contamination level. Total coliforms (TC), fecal coliforms (FC), heterotrophic bacteria (HB), and chemical oxygen demand (COD) were examined in the control and experimental samples to determine the treatment effectiveness. The findings showed that MNPs and Ag-MNPs were successfully synthesized with a mean size of 41 and 34 nm and the saturation magnetization of 62 and 67 emu/g, respectively. The results of advanced wastewater treatment showed that 105 mg/L nanoparticle dose, 70 min contact time, and 55% contamination level led to 0.65 TC, 0.48 FC, and 0.58 HB log reductions and 30.40% COD removal, on average. Increasing nanoparticle dose and contact time and decreasing contamination level enhanced the treatment efficacy. Switching from MNPs to Ag-MNPs significantly resulted in a 0.06 increase in TC, FC, and HB log reductions and a 6.16% increase in COD removal. Based on the findings, MNPs and Ag-MNPs are promising in the advanced wastewater treatment and disinfection. •Decorating MNPs with Ag-NPs enhanced the characteristics of the product.•TC, FC, and HB log reductions were 0.65, 0.48, and 0.58 in optimal conditions.•Average COD removal was 30.40% in optimal conditions.•Ag-MNPs were more efficient than MNPs in wastewater treatment and disinfection.