Summary:

The aim of the study was to determine the effectiveness of the removal of nitrogen compounds in two domestic sewage treatment plants operate based on activated sludge technology. In addition, the effect of sewage temperature in the bioreactors analyzed the effectiveness of the elimination rate. Also analyzed the treatment Turbojet EP-2 with a capacity designed from 1.2 to 1.8 m3•d-1, and treatment Turbojet EP-4 with a capacity of 3.5÷5.0 designed m3•d-1. During the study period the two objects were hydraulically underloaded. Based on studies conducted in 2008-2010 found that the average concentration of total nitrogen in raw sewage were 82.6 mgNog•dm-3 in the treatment plant Turbojet EP-2 and 102.0 mgNog•dm-3 in the treatment Turbojet EP-4, the mean concentration of total nitrogen in treated wastewater were 30.2 mgNog•dm-3 in the treatment Turbojet EP-2 and 65.5 mgNog•dm-3 in the treatment Turbojet EP-4. During the study found large fluctuations in the concentrations of total nitrogen in treated wastewater, which ranged from 12.2 to 77.1 mgNog•dm-3 in the treatment Turbojet EP-2 and from 15.3 to 130.7 mgNog•dm-3 in the treatment Turbojet EP-4. This demonstrates the instability occurring processes of nitrification and denitrification. High impact on the percentage of disposal process was nitrogen temperature treatment in bioreactors. This effect was confirmed correlations, which in sewage Turbojet EP-2 was high (rxy=0.67) and treatment Turbojet EP-4 very high (rxy=0.72). The removal efficiency of total nitrogen in wastewater Turbojet EP-2 was on average 61.3% during the study period, while in treatment Turbojet EP-4 36.2%. In both study sites in the bioreactors seen large fluctuations in water temperature. The lowest sewage temperature is oscillating in the range of 6÷8°C occurred during the three months in the year, which translates into a low efficiency of treatment during this period.