GREEN SYNTHESIS AND CHARACTERIZATION OF SILVER NANOPARTICLES (AGNPS) FROM BASIL (OCIMUM BASILICUM) SEEDS AND ITS EFFECTS ON WASTEWATER NUTRIENT REMOVAL BY CONSTRUCTED WETLANDS.

Background: In industrial and commercial items, silver nanoparticles (AgNPs) are widely used, which inevitably increases the release of AgNPs into wastewater which could have a negative impact on the sewage treatment plan. Objective: the experiments were carried out to assess the impact of AgNPs on nutrient removal in constructed wetlands. Materials and Methods: AgNPs were synthesized from seeds of basil (Ocimum basilicum) and characterized by the UV–Vis Spectrometer, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Results: NH3, NO2, NO3, P and PO4, were similar to the control group during the first week of the treatment period. The mean removal efficiencies of NH3, NO2, and P were 90.64%, 13.68%, and 13.09%, respectively. AgNPs had no impact on removing ammonia, nitrite and phosphorous at the level of 0.1 μg.L-1. The removal of NH3, NO2 and P showed no differences at the three levels of AgNPs in the first seven days of treatment, while the inhibition of NH3 removal occurred after two weeks of exposure to 0.1, 5 and 10 μg.L-1 each. After exposure for 4 weeks, NH3 and P concentrations were significantly increased, as well as a significant reduce was recorded in removal efficiency. Conclusion: High AgNPs' levels can affect the nutrients' removal after exposure for a long period of time, as the a positive relationship was recorded between the AgNPs' concentration with the removal efficiency.