Solar disinfection at low costs: an experimental approach towards up-scaled continuous flow systems

Abstract

SOlar DISinfection (SODIS) systems have been studied with the aim of maintaining pathogen removal efficiencies and low costs. Such systems are useful for quickly improving the situation of more than 700 million people worldwide that lack access to an improved water source. Currently, SODIS is mainly used with PET-bottles that are exposed to UV-A radiation for 6 h in the sun. Up-scaled continuous flow SODIS systems could instead provide a continuous source of drinking water, whereas the use of plastic tubes, easily available on local markets, ensures a low construction cost of the systems. Such tubes (PVC) were tested and the best option showed a UV-A transparency ratio of ∼50%, to be compared with ∼60% for PET-bottles. By using static batches in samples of this tube, the residence time was investigated and the results show that E. coli concentrations of 0 CFU/ml are reached within less than 4 h of exposure to solar radiation, starting from an initial concentration of 106 CFU/ml. It can be concluded that cheap, easily available plastic tubes can be used for treating contaminated water with the SODIS technique, which is promising for future investigations towards constructing continuous flow SODIS systems at low costs.