Influence of different UV-light created by a new UV-soource based on microwave irradiated plasma on bacteria in real waste water

The paper reports on the different disinfection effects by special UV light on bacteria in real waste water of a sewage plant. The disinfecting UV-light is not emitted by a common UV-light source using mercury excitation at 254nm. This light source creates the light by an excimer emission caused by a microwave irradiated plasma with main wavelengths maxima at 222nm (KrCl) and a combination of 222nm and 248 nm (KrF). Real waste water samples in Petri dishes were irradiated for different irradiation times and at different wavelengths. The disinfection effect on e.coli, coliforms except e.coli, gram-negatives except coliforms, total aerobic bacteria count as well as for enterobacteriaceae was determined and compared. A reduction for all investigated species, in microbiological low charged waste water(10(4)-10(5) cfu/ml) down to the detection limit of the semi-quantitative bacteria (test (10² cfu/ml) and in high charged water (>10(7) cfu/ml) down to 10³ cfu/ml, was obeserved. For total aerobic bacteria count the disinfection effect for the light with only 222 nm emission is as effectice as the combined irradiation at 222nm and 248nm. For enterobacteriaceae the combination of 222nm and 258nm light showed improved results when compared to 222nm alone