To be published: Brittney Dawney and Joshua M. Pearce, “Optimizing the solar water disinfection (SODIS) method by decreasing turbidity with NaCl”, Journal of Water, Sanitation and Hygiene for Development, 2(2) pp, 87-94 (2012). doi: 10.2166/washdev.2012.043.
Optimizing the Solar Water Disinfection (SODIS) Method by DecreasingTurbidity with NaCl
Solar water disinfection (SODIS) has proven to be effective at reducing diarrheal incidence in epidemiological intervention studies. However, the SODIS method is limited to waters of low turbidity (<30NTU). This study investigates the use of common table salt (NaCl) to reduce the turbidity of water containing suspended colloidal clay particles for use in the SODIS method. Three representative clays found in tropical soils(kaolinite, illite, and bentonite) were tested at three levels of turbidity (50, 100, and 200NTU) for their flocculating behaviour with multiple NaCl concentrations to find theoptimum. Supernatants were tested for sodium concentration for comparison againsthealth and taste thresholds.
Results show that unlike kaolinite and illite, pure bentonite solutions were shown to be very responsive to NaCl and produced supernatants with as low as 4 NTU (98% particle removal efficiency). This study has shown that NaCl, incombination with high-activity clay particles in solution, may effectively reduce turbidityto levels suitable for SODIS treatment, thereby expanding the number of people who canutilize the technology effectively.