Water Disinfection Using Fixed Bed Reactors Packed with Silver Nanoparticle Immobilized Glass Capillary Tubes

The present study focused on development of a robust point-of-use (POU) water disinfection device employing immobilized silver nanoparticles (AgNPs) for water disinfection in continuous flow through mode. Glass capillary tubes functionalized with positively charged amino groups using silane as the cross-linking agent facilitated the immobilization of citrate stabilized AgNPs. A fixed bed reactor (FBR) packed with these AgNP immobilized glass substrate was used for conducting POU water disinfection. The effect of various parameters such as, flow rate, initial concentration of bacteria and bed volume on disinfection performance of the device was evaluated. The total volume of water treated at breakpoint was found to improve with increase in flow rate and 2596-5172 bed volumes of water could be disinfected under the various conditions tested, i.e., empty bed contact time (EBCT) 0.29 to 5.8 min. Silver leaching studied under various operating conditions revealed minimal release of silver (<100 μg/l) in treated water over time throughout the duration of the studies. Plug flow reactor with dispersion (PFDR) model with open boundary condition showed good fit to the E-curve generated by pulse input of chloride tracer and revealed significant dispersion in the FBR. Antibacterial material exhaustion rate (AER) was significantly affected by the EBCT, empty bed volume of the FBR, and load of bacteria in the influent.