This thesis shows modelling of the biological stages of Domžale-Kamnik wastewater treatment plant (WWTP), with the aim to determine whether it would be possible to reduce the concentration of nitrogen compounds in the effluent only with smaller changes in the plant. In the first part of this thesis mathematical model of biological stages of Domžale-Kamnik WWTP was built in the software package GPS-X. The model considers only one lane of aerobic reactor and a settler for each stage. Model validation showed partial agreement with the daily averaged measurements. Lower agreement in measurements of ammonia and total nitrogen is probably due to bulking and denitrification in the secondary settlers, which the model does not take into account. In the second part of this thesis various simulation analyses were performed. It was tested how the model works at various bypass flow rates, oxygen concentrations in the aeration tanks, waste sludge flow rates from secondary settlers and recycle flow rates from the second to the first aeration stage. The results showed that the model works best with the bypass of 30%, which reduces ammonia nitrogen at the effluent by 22 %, whereas the concentration of total nitrogen remains the same. The reduction of the oxygen concentration to 1 mg/L in both aeration tanks cause the total nitrogen concentration to decrease by 12 %, although the concentration of ammonia nitrogen increases by 24 %. The model with increased waste sludge flow rate in the first settler to 160 m3/day and decreased in the second settler to 25 m3/day showed a reduction of total nitrogen concentration by 5 % and ammonia nitrogen by 9 %. Introducing an additional recycle from the second to the first stage reduces the total nitrogen by up to 27 %. However, this configuration works poorly at low temperatures, since the concentration of ammonia nitrogen is in this case highly increased.
F.17 Transfer of existing technologies, know-how, methods and procedures into practice
COBISS.SI-ID: 2049019