Antimicrobial Activity of Silver Nanoparticles and Cold Plasma in the Treatment of Hospital Wastewater

Hospitals discharge large amounts of pathogenic microbes into municipal wastewater and aquatic environments, posing significant challenges in terms of human health and ecological impacts. It is crucial to develop and implement effective techniques for managing and treating such wastewater. In this study, we aimed to design a potential strategy for the treatment of microbial hospital wastewater (HWW) by utilizing a combination of cold plasma (CP) and silver nanoparticles (Ag NPs). Melia azedarach (M. azedarach) leaf extract was used for the biosynthesis of Ag NPs by the green method. Various techniques were employed for Ag NPs characterization. The results obtained from the ultra-violet visible (UV-vis) spectroscopy showed ab absorbance peak at 430 nm. The scanning electron microscope (SEM) images revealed that the biosynthesized Ag NPs appeared spherical with an average size of 13.6 nm. X-ray diffraction (XRD) analysis determined the formation of Ag NPs. Fourier-transform infrared spectroscopy (FTIR) indicated the involvement of biomolecules in the reduction and stabilization of the Ag NPs. For the treatment of HWW, the antibacterial activity of Ag NPs was evaluated at the highest concentration (1:1), while CP was tested at the longest duration of exposure (60 s). The results showed a significant reduction in the average number of bacterial colonies to 18 and 5 colonies, respectively, compared to the control sample (without treatment), which had an average of 175 colonies. Moreover, the combined treatment of Ag NPs and CP resulted in complete inhibition of bacterial growth, with an average number of zero colonies for all samples and treatment conditions. Based on these findings, we believe that the synergistic effect between Ag NPs and CP holds promise as an advanced treatment technology for the elimination of microbes from HWW. This technology has the potential to contribute to a more sustainable and environmentally responsible healthcare system.