The Effect of Visible Light on Microbial Load Decrease in Facultative Stabilization Ponds

Almasi, Mohammadi, Dargahi
2017 Journal of Occupational and Environmental Health   unpublished
& Objectives: Coliforms removal rate is one of the indices to evaluate stabilization pond efficiency. Coliform is an important microbial index for water and wastewater. This study aimed to determine visible light effect on coliforms variations in stabilization pond. Methods: In this experimental study the effects of light (visible light and darkness), pH (<7, 7.1, 8, 8.1, and 9) and temperature (10 and 30°C) on facultative stabilization pond were investigated. Mixed samples were taken on a
more » ... ere taken on a weekly base for six months. Coliform colonies were counted using 9 tube method. Coliform deterioration constant was calculated by Maraise model. Subsequently, data were analyzed by SPSS version 20. Results: The results showed light to affect negatively coliform deterioration constant and increased their survival time. Low pH increased coliform death rate and no significant difference was observed in death rates at 10 °c and 30°C (p<0.05). Conclusion: Low temperature is not barrier for facultative stabilization pond. Regarding to positive effect of light on coliform death, use of facultative stabilization pond in warm climate is suggested.