Etid la izole kolifaj diferan nan dlo ize minisipal trete. Kolifaj yo se viris ki enfekte bakteri E.coli, epi yo ka itilize kòm modèl pou viris enterik imen nan etid dezenfeksyon. Prèske mwatye nan kolifaj izole yo te trè rezistan a klò oswa radyasyon UV, e se poutèt sa ni klò ni radyasyon UV poukont yo pa t efikas kont tout kolifaj.
"This highlights the importance of a combined treatment," says Doctoral Student Alyaa Zyara, MSc, from the University of Eastern Finland, who presented the results in her doctoral dissertation.
Lè kolifaj yo te premye ekspoze a yon konsantrasyon ba klò ({{0}}.1 oswa 0.5 mg Cl/L) pou 10 minit ki te swiv pa ba radyasyon UV (sèlman 22 mWs/cm2), plis pase 99.9 pousan nan tout kolifaj etidye yo te vin inaktive. Sepandan, lè yo te ranvèse lòd tretman an (UV an premye, dezyèm klò), dezenfeksyon an te mwens efikas.
"It is more effective to first use a low dosage of chlorine followed by a low dosage of UV radiation than to use high chlorine or UV dosages alone. The order of treatment is also important: using UV radiation first and chlorine second was less effective. In other words, the combination treatment using chlorine first and UV second can be recommended as a disinfection method for viruses."
The study also tested novel UV-LED technology, as UV-LEDs are a new method for disinfecting drinking water. The study used UV-LEDs operating at a wavelength of 270 nm and with a 120 mW irradiation capacity, which haven't been used in disinfection studies before. As little as 2 minutes of this UV-LED treatment was enough to cause a 90-99.9 percent reduction in the coliphages tested in a 5.2-litre reactor. Irradiation time of 10 minutes in the same reactor increased the reductions to 99.99 -- 99.999 percent . A traditional mercury UV lamp at a 254 nm wavelength caused similar or slightly higher reductions in 2 or 10 minutes, but the water volume was only 10 millilitres.
"UV-LEDs are a promising method for disinfecting water, since they consume less energy than traditional mercury UV lamps. Furthermore, as UV-LEDs do not contain any mercury, they are safer for the environment."
The findings were originally reported in Journal of Water and Health, and Water.
