International Journal of Fisheries and Aquatic Studies
2023, Vol. 11, Issue 6, Part B
Solar water disinfection: A probabilistic methodology for predicting exposure period from time series of insolation data
Author(s): Ekene Jude Nwankwo
Abstract: Complete and irreversible inactivation of microbial pathogens in solar water disinfection (SODIS) requires that a certain irradiation/disinfection threshold is received uninterruptedly in a day. In this study, each exposure day is viewed as a Bernoulli trial and binomial distribution was applied to predict monthly exposure periods at different confidence levels. The procedure was applied to 300 locations and 12 months in Nigeria using 10 years of daily solar radiation data obtained from the NASA Langley database, which resulted in 3600 datasets. Homogeneity tests conducted on the datasets using Pettitt’s method showed that 93% of the NASA’s data collected over Nigeria are not homogeneous, suggesting that the data cannot be reliably used for the assessment of SODIS applicability and prediction of the exposure period. Exposure periods predicted using the model suggest that 2 days of exposure would be sufficient at 90%, 95%, and 99% confidence levels if at least 45.0%, 47.5%, and 49.5% of the days in a month meet the disinfection threshold, respectively. The minimum mean values of datasets that still resulted in a 2-day exposure period were 544.3, 573.4, and 627.8 W/m2 at 90%, 95%, and 99% confidence levels, respectively. Validation experiment showed 1- and 2-day exposure periods predicted at 90%, 95%, and 99% confidence levels respectively showed 92%, 85%, and 59% agreement when compared with the actual exposure period. The results concluded that the exceedance probability and return period of the disinfection threshold is a more reliable metric for assessing SODIS applicability than the seasonal averages of radiation intensity.
DOI: 10.22271/fish.2023.v11.i6b.2940Pages: 132-148 | 194 Views 75 DownloadsDownload Full Article: Click Here
How to cite this article:
Ekene Jude Nwankwo.
Solar water disinfection: A probabilistic methodology for predicting exposure period from time series of insolation data. Int J Fish Aquat Stud 2023;11(6):132-148. DOI:
https://doi.org/10.22271/fish.2023.v11.i6b.2940