Effect of Zero Valent Iron Nanoparticles on Removal of Antibiotic Resistant Genes of Heterotrophic Bacteria in Urban Wastewater

Background and Application of nanomaterials is growing in removing various contaminants, pharmaceuticals, and in deactivation of water or sewage bacteria. However, the ability to degrade or eliminate the genetic components of bacteria by nanoparticles and preventing the increasing trend of antibiotic resistance from sewage treatment plants needs to be further investigated. This study aimed at eliminating the genetic components (antibiotic resistance genes) of heterotrophic bacteria from wastewater by Zero Valent Iron Nanoparticles.
To eliminate genetic components of bacteria, the ability of nZVI was measured by cellular and molecular methods to remove the genetic components of the bacteria. Selected genes included TetW (tetracycline) Ctx-m-32 (Ceftazidime), and CmlA1 (Chloramphenicol). Polymerase chain reaction (PCR) and specific primers were used to detect resistant genes.
The average concentrations of HPC and ARBs were 1.68 × 105 and 2.58 × 104 cfu/mL in primary effluent. The mean values for ARGs were (TetW)=33.71 ±10.66, (CmlA1)=57.71 ±11.60, and (Ctx-m-32)=37.71 ±4.85 ng/μl after the experiments. The proposed software model for HPC and ARBs included nZVI= 20-23 mg/l, QN2=7-7.8l/min, and time=23-30 min and for ARGs it included nZVI=28-30 mg/l, QN2=7-7.8l/min, and time=30-38 min.
Zero Valent Iron Nanoparticles can degrade and eliminate heterotrophic bacteria, and decompose and eliminate the genetic components of bacteria and antibiotic resistance genes. Unlike the chlorination units of sewage treatment plants that increase antibiotic resistance among effluent bacteria, iron significantly reduces the populations of antibiotic resistant bacteria. Compared to TetW and CmlA1, the Ctx-m-32 genes have high stability and durability against nZVI.