NITROGEN REMOVAL FROM MUNICIPAL WASTEWATER USING INTEGRATED FIXED FILM ACTIVATED SLUDGE PROCESS AND ANOXIC PROCESS

Abstract

This research was carried out using lab-scaled Integrated Fixed Film Activated Sludge (IFAS) process with fabious media and anoxic process in order to reduce the concentration of ammonia nitrogen and nitrate nitrogen in municipal wastewater from Yangon City, Myanmar. The required wastewater sample was collected from the wastewater treatment plant of Yangon City Development Committee (YCDC). Ten experiments were conducted with five operational conditions and they lasted about four months from February to May 2018. The rate of air supply for the aeration tank through these experiments was about 8 m3 /day. This paper describes the evaluation on nitrogen removal efficiency of the lab-scaled treatment system depending on the results from the experiments. Due to the different operational conditions through these experiments, the F/M ratio of IFAS process varied between 0.1 and 0.9 d -1 and SRT of IFAS process ranged between 6.0 days and 8.3 days. Moreover, the F/M ratio fluctuated between 0.2 d -1 and 0.7 d -1 as well as the Specific Rate of Denitrification (SRDN) altered between 0.23 g NO3-N/g MLSS and 0.33 g NO3-N/g MLSS in the anoxic process. According to the outcomes of the experiments, the maximum removal efficiency for ammonia nitrogen and nitrate nitrogen were about 98.2% and 97.7%, respectively. However, the optimum treatment efficiency for both NH3-N and NO3-N concentration was obtained at the ninth experiment with about 0.1 d-1 of the F/M ratio and about 6.4 days of SRT in aerobic reactor while the F/M ratio, SRDN and anoxic residence time of anoxic process were about 0.26 d-1 , 0.27 g NO3-N/ g MLSS and 48 hours, respectively. About 500 mg/l of ammonia nitrogen can be reduced to about 30 mg/l and about 2600 mg/l of nitrate nitrogen can be reduced to about 61 mg/l, respectively in this ninth experiment. The optimum treatment efficiency for ammonia nitrogen and nitrate nitrogen were about 94.0 % and 98.0 %, respectively.