Photo-degradation of microbes in hand-dug well-water using different radiation sources

Abstract

Microbial bacteria in well-water have been treated using three different radiations and efficiency of treatment determined. The radiations were SUV (Sun with UV); SNoUV (Sun with NoUV, sun with UV portion filtered out) and LEDUV (radiations from LED source). Reduction in the Raman water peak at 526 nm and DOM fluorescence intensity at 550 nm indicate that the DOM experienced photo degradation when exposed to radiation. A first-order kinetic equation was used to model this decline and degradation rate constant K calculated from the slope of the resulting natural log graph. The half-life was determined. At 526 nm and 550 nm fluorescence peaks trend downward with time, indicating a reduction in DOM. Sample exposed to SUV showed greatest reduction and SNoUV the least. SUV had least half-life, and registered shortest time in reducing the DOM to one-half its initial value (fastest sample purification rate) while SNoUV registered the highest half-life. There was a count of coliform bacteria and Total Heterotrophic Bacteria using culture techniques before and after exposure to the radiations. Using the sum of all the microbes, the first-order kinetic equation was used to model the decrease with time and degradation rates K and half-life calculated. Exposure to SUV showed fastest decline and SNoUV slowest. This confirmed findings in LIF study, with the order of efficiency of radiation sources also in agreement with findings of the LIF. A sample was kept in the dark and analyzed. For that, its fluorescence peaks fluctuated and showed just a minimal reduction in the microbes