Silver nanowire-decorated glass fiber filters for bacteria removal from water


Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Graduate School of Natural and Applied Sciences, Turkey

Approval Date: 2019

Thesis Language: English

Student: ECEM BAHÇELİOĞLU

Principal Consultant (For Co-Consultant Theses): Tuba Hande Bayramoğlu

Co-Consultant: Hüsnü Emrah Ünalan

Abstract:

Investigation of a new, low-cost, safe and highly efficient water disinfection alternative to conventional methods has prime importance. This study aims to develop silver nanowire decorated glass fiber (AgNW-GF) filters for the removal of E. coli from water. This study is one of the first studies to fabricate a novel AgNW-GF filter and to investigate its use for point-of-use (POU) water disinfection. To this purpose, effect of flow rate, AgNW loading and influent E. coli concentration on the removal efficiency of E. coli and Ag release from AgNW-GF filters were investigated. In addition, effect of volume of filtrate on Ag release was also analyzed. Disk diffusion tests revealed that AgNW-GF filters having different AgNW loadings had antibacterial effects against E. coli at concentration range of 103 – 108 CFU/ml. In order to investigate optimal conditions at which AgNW-GF filters achieved the highest removal efficiencies, flow tests were conducted with different flow rates (1, 2.5, 5 ml/min), AgNW loadings (0.95, 4.8, 9.9 mg/g) and E. coli concentrations (103, 105, 108 CFU/ml). Optimal flow rate, AgNW loading and influent E. coli concentration were found out as 1 ml/min, 9.9 mg/g, and 103 CFU/ml, respectively. The highest removal efficiency was obtained as 2.12 log after two-stage serial filtration application applied under optimal conditions. The released Ag amounts were all below the limit value of 100 ppb for potable water. Under determined optimal conditions, AgNW-GF filter was found as a promising alternative for POU water disinfection method to be used in contaminated natural water (<103 CFU/ml). In order to achieve higher removal efficiencies for more contaminated water and improve POU water disinfection with AgNW-GF filters, low-voltage can be applied to the developed AgNW-GF POU disinfection system.