The Influence of Temperature Fluctuation on the Efficiency of Deammonification Process During Wastewater Treatment

Deammonification is biological process, where ammonia is removed out of the wastewater. Advantages, compared to traditional nitrification/denitrification, consist in saving energy used to aeration and lower requirements to organic substrate. Anammox bacteria, which are realizing the process are very sensitive. Their optimal temperature is about 35 °C to 45 °C. In real life, the treatment of wastewater runs in lower temperature. This thesis is focused on the influence of temperature fluctuation on efficiency of deammonification. For the experiment was used model with CSTR reactor, which deals with adjusted sludge water from anaerobic sludge stabilization. Sludge water from ÚČOV Praha was diluted by tap water and nitrite nitrogen was added. Anammox bacteria were cultivated in form of suspension (activated sludge), which was obtained in anammox reactor from estonian university in Tartu. The experiment lasted 280 days. It was divided into three phases, depending on changing temperature. In the first part, the average temperature was 23,3 °C, in the second part 27,5 °C, and in the third part was setted up the temperature decrease from 27 °C to 16,2 °C. The volume load of Ntotal was between 0,024 and 0,174 kg/(m3.d). With increasing temperature was noticed increasing efficiency of N-amon and N- NO2- removal. The hypothesis, that anammox rector can be succesfully operated in low temperature (18,3 °C), was confirmed. Inhibition caused by temperature was noticed under 16,2 °C. At this point, efficiency of removal N-amon, N-NO2-, N-NO3- and Ntotal decreased. Anammox bacteria approved ability to deal with short-term (1 week) temperature drop. After increase of temperature from 16,2 °C back to 23,9 °C, it was detected high ability to remove nitrogen forms. Average effectivity of Ntotal removal was 45,1 %. Higher efficiency was reached of N-amon, it was 72,0 %. During the experiment was removed 88,9 % N-NO2-. Because of the collected results, we can say, the annamox reactor can be sucessfully run in lower temperatures around 16,2 °C, if inhibition caused by temperature is short-term