Vol.:(0123456789) 1 3 Photochemical & Photobiological Sciences (2021) 20:123–137 https://doi.org/10.1007/s43630-020-00008-4 ORIGINAL PAPERS A new continuous‑fow solar water disinfection system inactivating cysts of Acanthamoeba castellanii, and bacteria Beni Jequicene Mussengue Chaúque 1,3  · Antônio Domingues Benetti 2  · Gertrudes Corção 1  · Carlos Eugênio Silva 1  · Rodrigo Fernandes Gonçalves 1  · Marilise B. Rott 1 Received: 15 December 2020 / Accepted: 16 December 2020 / Published online: 25 January 2021 © The Author(s), under exclusive licence to European Photochemistry Association,European Society for Photobiology 2021 Abstract Solar water disinfection (SODIS) is an efective and inexpensive microbiological water treatment technique, applicable to communities lacking access to safely managed drinking water services, however, the lower volume of treated water per day (< 2.5 L per batch) is a limitation for the conventional SODIS process. To overcome this limitation, a continuous-fow solar water disinfection system was developed and tested for inactivation of Acanthamoeba castellanii cysts and Escherichia coli, Salmonella Typhimurium, Enterococcus faecalis, and Pseudomonas aeruginosa. The system consisted of a solar heater composed of a cylindrical-parabolic concentrator and a UV irradiator formed by a fresnel-type fat concentrator combined with a cylindrical-parabolic concentrator. Deionized water with low or high turbidity (< 1 or 50 nephelometric turbidity unit (NTU) where previously contaminated by 10 8  Cysts/L or 10 5 –10 6  CFU/mL of each of four bacterial species. Then was pumped from the heating tank fowing through the heater and through the UV irradiator, then returning to the heating tank, until reaching 45, 55, 60 or 70 °C. The water was kept at the desired temperature, fowing through the UV irradiator for 0.5 and 10 min. Trophozoites were not recovered from cysts (during 20 days of incubation) when water with < 1 NTU was exposed to UV and 60 °C for 0.5 min. In water with 50 NTU, the same result was obtained after 10 min. In water with < 1 NTU, the inactivation of all bacteria was achieved when the water with < 1 NTU was exposed to 55 °C and UV for 0.5 min; in water, with 50 NTU the same result was achieved by exposure to 60 °C and UV for 0.5 min. The prototype processes 1 L of water every 90s. The system is efective and has the potential to be applied as an alternative to the large-scale public drinking water supply. * Marilise B. Rott marilise.rott@ufrgs.br 1 Department of Microbiology, Immunology and Parasitology, Institute of Basic Health Sciences, Universidade Federal Do Rio Grande Do Sul, Sarmento Leite Street, N 500, Porto Alegre, Rio Grande do Sul 90050-170, Brazil 2 Department of Hydraulic Works, Hydraulic Research Institute, Universidade Federal Do Rio Grande Do Sul, Bento Gonçalves street 9500, Porto Alegre, Brazil 3 Department of Natural Sciences, Mathematics and Statistics, Niassa Branch, Universidade Rovuma, Nangala campus, Lichinga City, Mozambique