Solar Disinfection in a Community-Scale Water Treatment System: An Analysis of Design Parameters for Humanitarian Engineering and System Sustainability

SODIS, solar disinfection of water in plastic bottles, is a well-known water treatment method in communities lacking developed infrastructure. While SODIS is commonly employed by individuals and family units needing clean drinking water in many parts of the world, a community-scale solar disinfection system is presented in this paper as sustainable, humanitarian engineering concept. A community-scale system may be accepted by communities that reject the individual-bottle SODIS method. The triple bottom line of sustainability (society, environment, and economy) may be met by community-scale systems. To test the treatment effectiveness of the system, experiments were conducted to quantify the solar inactivation rate of total coliform bacteria from contaminated source water. Solar disinfection configurations in tanks and bottles were analyzed for the effect of ultraviolet (UV) light index, water temperature, tank color, plastic covering, and duration of sun exposure. A black tank, covered with a clear, plastic drop cloth of 2 MIL (0.0508 mm) thickness provided the highest inactivation rate of total coliforms. A contour plot of UV index versus water temperature provides guidelines for minimum required sun exposure times for disinfection.