Long-term disinfection performance of silver nanoparticles impregnated membranes

Abstract

There is a major need for effective and sustainable point-of-use (POU) methods for drinking water treatment especially in remote rural areas. We present a study on the effectiveness and sustainability of POU woven fabric microfiltration (WFMF) membranes impregnated with silver nanoparticles (AgNPs) for water disinfection. The critical aspects investigated include: the period of effective disinfection performance; quantification of silver elution from the membranes with time; and the relationship between silver elution and the disinfection efficacy. The disk diffusion and glass bottle tests confirmed the antimicrobial effectiveness of the coated membranes as distinguished from the uncoated membranes which showed no antimicrobial properties under similar conditions. Synthetic feed water (10,000–85,000 Colony Forming Units/100 mL Escherichia coli) was treated for 90 d and no E. coli was detected in permeate for 63 d of continuous operation. Silver elution from the membranes was far below the maximum acceptable limit of 0.1 mg/L for drinking water throughout the period of investigation. To the best of our knowledge, this is the first study to investigate the long-term performance of AgNPs-coated WFMF membranes. The cost effective and extremely robust-coated membranes provided clean and safe drinking water for at least two months of continuous operation.

Keywords:

• Disinfection
• E. coli
• Membranes
• Silver nanoparticles
• Silver elution

Acknowledgements

The authors would like to acknowledge Durban University of Technology for sponsoring this work. Sincere gratitude to Jimmy Chetty from the Department of Chemistry for the ICP-AES tests and the Institute of Water and Waste Water Treatment for the E. coli testing facilities.