A solar radiation and biosand filtration system for cooking and water treatment

A significant portion of the world’s rural population does not have access to adequate sources of electricity and fuel to produce healthy food and clean water. Many rural areas, however, have an abundance of solar radiation which can be harnessed for cooking and water treatment. This paper presents the design and testing of a solar radiation and biosand filtration system that can provide cooking and water treatment capabilities. The proposed system addresses a need for a solar cooker that is durable, theft resistant, and efficient for use by an entire village. Thermal pasteurization is used for water treatment in the proposed system, and a built prototype is analyzed for heat transfer and water treatment efficiency. Water treatment is assessed through turbidity testing and Escherichia coli + other coliform counts. Given proper sunlight exposure, the proposed system reaches adequate temperatures to pasteurize water as documented with thermocouples, but testing in central Pennsylvania is difficult because of relatively low direct normal irradiance. A decrease in Escherichia coli and other coliform counts has been observed for post-treatment versus pretreatment water samples, but the counts are not sufficient to meet the Environmental Protection Agency drinking water standards. This correlates with the inability to maintain the warmer temperatures in central Pennsylvania during the cooler nights.