Evaluation of Indicator Bacteria Removal in Wastewater Treatment Processes

The results of elimination of total coliforms, E.coli and enterococci from wastewater during mechanical-chemical treatment as well as biological treatment operated in the MUCT system in a full-scale wastewater treatment plant are presented. It was proved that the change of treatment technology resulted in improving bacteria removal efficiency- reduction of the number of total coliforms increased from 0.9 log10 to 2.5 log10 and E. coli from 1.0 log10 to 2.3 log10. The UV disinfection of effluent from the MUCT system allowed for further reduction of the number of bacteria to 3.4 logio when the dose of UV radiation equal to 40 mWs/cm2 was applied and to 3.8 logio at the dose of 52 mWs/cm2. The geometric mean number of bacteria in the effluent after UV disinfection with the dose 40 mWs/cm2 was below 50/100 ml of total coliforms, 15/100 ml of E.coli and approximately 30/100 ml of enterococci