Szukana fraza: [Abstract = A high efficiency of COD removal, obtained at DO concentration of 0,5\-\-1,0 mg O_2\/l, creates possibilities for a substantial reduction of exploatation costs for wastewater treatment plants on MBSBBR reactors. The analysis of the influence of a preset DO level on nitrogen transformation processes was found that together with an increase of DO concentration in the aerobic phases of the cycle an increase of the nitrification rate and decrease of the simultaneous denitrification rate can be observed.]