ISBN: 1 84057 440 2
Published Date: 28/06/2007
The sunlight-induced inactivation of bacterial indicator organisms, F-specific bacteriophage and poliovirus 2 was investigated in a series of experiments.
An artificial light source was used to irradiate a range of sewage-spiked waters formulated to provide a pertinent range of temperature, turbidity and salinity combinations. Inactivation curves were generated for each of the microorganisms (primary linear model). Enterococci were the most resistant.
Although all primary model fits were excellent, secondary models (predictive equations) were fitted with varying degrees of success. The faecal coliform data produced the best fit, but enterococci inactivation rates could not be modelled. The heterogeneity of the enterococci group, their cell physiology and their propensity to occur in chains were identified as potential sources of variability in their response to light-mediated inactivation.
The validity of the predictive equations was assessed by producing inactivation data using natural waters and light and comparing them with predictions from the models. For faecal coliforms, there was a consistent correlation between observed and predicted values. No equivalent correlation was observed for the other microorganisms. When the artificial light was replaced with natural sunlight, the fit was poor for all the microorganisms.