| Summary: | The main aim of the study was to optimize Partial Nitritation/Anammox process operated in pilot-scale integrated fixed film activated sludge (IFAS) mode supplied with low-temperature mainstream wastewater and efficiency evaluation based on laboratory analysis and data from online sensors. Main tasks of research work were to stabilize the ongoing process and find the optimal conditions for maximizing effects of nitrogen removal. The use of online sensors (dissolved oxygen, pH, conductivity, oxidation-reduction potential, NH4-N, NO3-N and NO2-N) has allowed continuous process monitoring. During research period the influent wastewater flow, recirculated sludge flow, time of aeration, set point of dissolved oxygen and temperature were changed. Flow of influent wastewater varied between 11.2 and 16.8 L/h resulting in HRT varying between 11.9 and 17.9h. Different strategies of aeration were tested: 20, 25 and 30 minutes of aeration in one-hour cycle with DO values of 1.0, 1.3 and 1.5 mg O2/L. The best result of nitrogen removal efficiency for IFAS reactor operated at 15°C was 46.6% (based on online data) at oxygen concentration value of 1.3 mg O2/L, with 20 minutes of aeration and 40 minutes without aeration in 1-hour cycle. After increase of temperature to 17°C higher nitrogen removal efficiency was obtained with maximum value of 48.0% (based on online data).
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