The inactivation of microbes by sunlight: Solar disinfection as a water treatment process
This chapter reviews the solar water treatment. Sunlight is an important factor responsible for the inactivation of fecal bacteria in many natural environments, including fresh water and sea water, bathing waters, and waste waters. The chapter discusses the mechanisms of solar disinfection. This includes optical inactivation, thermal inactivation, and interaction between optical and thermal effects. At its simplest, batch-process solar disinfection, the method involves filling a transparent glass or plastic vessel with contaminated water and then keeping the vessel in full-strength sunlight for several hours to inactivate pathogenic microbes. Solar radiation can inactivate a wide range of micro-organisms—including fecal indicator bacteria such as Escherichia coli, water-borne pathogenic bacteria such as Salmonella typhi and Shigella flexneri, along with various yeasts and molds. Furthermore, solar disinfection is not universally applicable; it may be appropriate under circumstances in which there is no realistic alternative treatment process and where there is an unfulfilled need for safer water.