D'aonraigh an staidéar colophages éagsúla ó fhuíolluisce cóireáilte cathrach. Is víris iad colophages a ionfhabhtaíonn baictéir E.coli, agus is féidir iad a úsáid mar mhúnlaí do víris eintreach daonna i staidéir díghalrúcháin. Bhí beagnach leath de na coliphages scoite an-fhrithsheasmhach in aghaidh clóirín nó radaíocht UV, agus is é sin an fáth nach raibh clóirín ná radaíocht UV amháin éifeachtach i gcoinne gach drólannach.
"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.
Nuair a nochtaíodh coliphages don chéad uair do thiúchan íseal clóirín ({{{0}}.1 nó 0.5 mg Cl/L) ar feadh 10 nóiméad agus ina dhiaidh radaíocht UV íseal (ach 22 mWs/cm2), níos mó ná 99.9 faoin gcéad de díghníomhaíodh gach ceann de na coliphages a ndearnadh staidéar orthu. Mar sin féin, nuair a aisiompaíodh ordú na cóireála (UV ar dtús, clóirín sa dara háit), ní raibh an díghalrú i bhfad níos lú éifeachtach.
"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.
