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 treat ment operated in the MUCT system in a full-scale wastewater treatment plant are presented. It was proved that the change of treatment technology resul ted in improving bacteria removal efficiency - reduction of the number of t otal coliforms increased from 0.9 log(10) to 2.5 log(10) and E. coli from 1 .0 log(10) to 2.3 log(10). The UV disinfection of effluent from the MUCT sy stem allowed for further reduction of the number of bacteria to 3.4 log(10) when the dose of UV radiation equal to 40 mWs/cm(2) was applied and to 3.8 log(10) at the dose of 52 mWs/cm(2). The geometric mean number of bacteria in the effluent after UV disinfection with the dose 40 mWs/cm(2) was below 50/100 ml of total coliforms, 15/100 ml of E.coli and approximately 30/100 ml of enterococci.