In the case of Enterobacter cloacae, as the test organism for determining the colony count at 36°C, the UV disinfection device reduced the test organism by approx. 4 log10 levels, i.e. 99.99% of the test organism was reduced. In the effluent, the limit value of the Drinking Water Ordinance for the colony count at 36°C of 100 CFU/ml was easily complied with in all five samples. The maximum value in the effluent was 1 CFU/ml (in two samples). In three samples, the value was 0/ml, i.e. the bacterial concentration was below the detection limit of the method.

In the case of Pseudomonas aeruginosa, the bacteria were reduced by almost 5 log10 levels. On average, Pseudomonas aeruginosa was reduced by 99.9985 %. Small amounts of Pseudomonas aeruginosa were still detectable in the effluent of the UV disinfector, on average 5.6 CFU/100 ml.

In the case of E. coli, the bacteria were reduced by approx. 6 log10 levels. The UV disinfection device reduced E. coli by 99.9999 %. Minimal amounts of E. coli were still detected in three samples in the effluent (1 or 2 CFU/100 ml). Two samples were free of E. coli in 100 ml.

Overall, the UV disinfection device PURION 1000 can be confirmed to have very good effectiveness during the conducted test operation. The test organisms used were reduced by 4 to 6 log10 steps under the described experimental conditions.

Assuming a minimum reduction of bacteria by 4 log10 steps, water with colony counts up to a maximum of 10^6 CFU/ml or E. coli concentrations lower than 10,000/100 ml can be disinfected using the PURION 1000 UV disinfection device under the described experimental conditions, ensuring that the microbiological limits of the Drinking Water Ordinance are met.

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