Disinfecting Potentials and Eco-Safety Evaluation of Nano-treated Surface Water Resources by Biogenic Silver Nanoparticles Using Bacterial and Phytotoxicity Indices
Résumé
Nanotreated wastewater safety is assessed via phytotoxicity tests, checking its impact on plants. So, understanding how nanoparticles treated surface water affect plant growth is key to assessing environmental risks to food safety and human health. This study was undertaken to determine the disinfecting potentials and ecological safety evaluation of post - nanotreated surface water resources by biogenic silver nanoparticles using bacterial load and phytotoxicity indices. M. oleifera and C. papaya aqueous seed extracts were phytochemically analyzed and used to synthesize silver nanoparticles via titration. The nanoparticles were characterized using UV-VIS spectroscopy. Surface water samples (1 L) treated with 5 mg/mL nanoparticles for 30 - 120 min were analyzed for physicochemical and bacterial changes. The phytochemical results revealed that flavonoids, terpenoids and saponins were present in both M. oleifera and C. papaya aqueous seed extracts. The conversion of colourless silver nitrate to brownish then to dark brown colour after 24 hr confirming the successful synthesis of silver nanoparticles. The UV - Vis spectral revealed that the maximum peak of both AgNPs was at 400 nm each while the minimum peaks were at 800 nm and 700 nm, respectively. It revealed that M. oleifera and C. papaya-synthesized silver nanoparticles effectively reduced bacteria count in water samples. The nanoparticles' effect increased with contact time (30 - 120 min) showing time dependence (P < 0.05). Also, it revealed that the bacterial strains were all Gram negative short rods and classically identified using Bergeys’ Manual as Klebsiella pneumoniae, Enterobacter aerogenes and Escherichia coli as the indigenious possible bacterial pathogens. Moreso, sample A of C. papaya treatment had the highest (68.19 %) and sample D of M. oleifera treatment had the lowest (29.74 %) germination index in Zea mays L. while sample C of CaOCl2 treatment had the highest (45.83 %) and sample E of C. papaya treatment had the lowest (6.66 %) germination index in Phaseolus vulgaris. Thus, the present study demonstrated the facile synthesis of low cost, moderate ecofriendly and efficient green water purifiers.
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