Proceedings

Solar radiation is considered the primary route for disinfection of pathogenic bacteria in maturation ponds. There is scarce information on depth profiling and attenuation of Photosynthetically Active Radiation (PAR), UV-A and UV-B in shallow maturation ponds operating in tropical climates. Data of solar irradiance of the three wavelengths, together with turbidity, have been acquired from different depths for over one year in a shallow maturation pond (45 cm of depth) operating in Brazil. UV-A and UV-B were still detected at 10 cm from the surface, but from 15 cm both waves were undetectable. PAR was still detected at 30 cm of depth. Attenuation of irradiation showed to be related to turbidity. Attenuation coefficients were calculated and a model including log10 of turbidity is proposed for predicting irradiance attenuation.