Predicting the bactericidal efficacy of solar disinfection (SODIS): from kinetic modeling of in vitro tests towards the in silico forecast of E. coli inactivation

In this study, the possibility of predicting the efficacy of Solar water disinfection (SODIS) for the removal of bacterial pathogens was assessed by the development of a three-level plan: firstly, systematic E. coli inactivation was performed (in vitro) in Lake Geneva water, under otherwise controlled conditions of water temperature (20–50 °C), sunlight intensity (0–1200 W/m2), presence of natural dissolved organic matter (DOM, 0–6 mg/L) and turbidity (0–50 NTU). As a second step a kinetic evaluation led to the selection of the most relevant parameters to be included in a novel static and dynamic model theoretical formulation. The static and dynamic models reliably described the experimental findings (bacterial inactivation under various climatic conditions) and were considered as equally eligible candidates for disinfection modeling. The final step considered ambient temperature, incident radiation and cloud-cover data to forecast (in silico) SODIS efficacy in Africa as a case study. The simulation results were compared with the experimental data and indicated that most African regions are suitable for SODIS processes, but there are areas of risk correlated with climatological conditions (cloud-cover and temperature). The results of this study could be applied for regional in decision-making strategies for application of SODIS or in the search for viable alternatives to SODIS in cases where it is deemed unsuitable.