Inactivation of Escherichia Coli in Water using UV Light in Continuous flow Reactor

In rare progress countries, paucity of healthy drinking water is one of the most challenging health problems. One of the common and most severe pollution of water resources is biological contamination. These deaths are mainly due to gastrointestinal infections from Escherichia coli species. In this research work an attempt was done to do disinfection of water by UV- light in continuous flow reactor. Physico-chemical parameters viz. turbidity (1NTU to 6 NTU), pH (6 to 8), temperature (23.9oC to 25.4 oC), total hardness (9.9mg/l to 234mg/l) and bacteriological parameter E.coli (92 to 2400MPN/100ml) were investigated before and after disinfection which is in permissible limits as per IS:10500 (2012) standards except E.coli concentration . As the water flow through the continuous flow reactor, bacteria were exposed to 240nm to 280nm ultraviolet light radiation which causes damage to genetic molecules. First the disinfection was done with uncovered experimental set-up having pair of 6 watts UV light used for microbial inactivation i.e. E-coli, secondly same experimental set-up was modified by covering it with reflecting mirrors i.e. covered experimental set-up to disinfect the water, thirdly same experimental set-up was modified by increasing the length and decreasing the height of experimental set-up and lastly same experimental set-up was modified by increasing the intensity by introducing another pair of 11 watts UV light. The complete experimental set-up runs on three flowrates viz. 100ml/min, 55ml/min, 40ml/min. The uncovered experimental set-up was running at different flow rates does not show any inactivation of E.coli. The modified covered experimental Set-up running at different flow rates show 33% inactivation of E.coli. The modified experimental set-up with increasing length running at different flow rates show 90% (1 log reduction) inactivation of E.coli. The modified experimental set-up with increasing intensity running in all three flowrates showed complete 3 log reduction inactivation of E.coli.