WAtER diSinfEction uSing nAnotEchnology foR SAfER iRRigAtion: A dEmonStRAtion PRojEct in SWAzilAnd

This case study assesses the feasibility of a point-of-use (POU), nanomaterial-enabled photocatalytic water treatment device for use in rural areas in Swaziland. Small reservoirs provide water for irrigation and community consumption, but this water is highly contaminated with human and animal wastes. A prototype fluidized bed photoreactor—amended with nano-sized TiO2 coated on silica beads (60 wt%) and illuminated by UV light (254 nm, 18 W cm-2)—was capable of removing 99.9% of bacteria and viruses with less than 60 seconds of contact time. However, control tests showed that the majority of the disinfection was accomplished by UV light alone, with the photocatalytic material unable to significantly add to the disinfection at such short contact times. A potential benefit of using nano-sized TiO2 photocatalyst was the removal of a model pesticide (carbaryl) whose concentration was reduced by approximately 50% (compared to controls) with a contact time of 3 minutes. This research highlights the importance of POU water treatment systems, and demonstrates the potential feasibility and limitations of using nanotechnologyenabled small reactors to help relieve high water-related disease and mortality rates in developing countries.