Nitrogen removal in submerged MBR with intermittent aeration

Abstract

For this paper, synthetic wastewater was treated in two membrane bioreactors, with an accent on the removal of total nitrogen through nitrification and denitrification processes conducted as a batch process and as a process with continuous feed inflow. In the first bioreactor, with the flat sheet membrane, the specific denitrification rate during the batch process was 1.83 mg NO₃ ⁻-N/g MLSS h, with the glucose added all at once at the start of the process. When the glucose was being added continuously, specific denitrification rate was 1.2 mg NO₃ ⁻-N/g MLSS h. Without added glucose, specific denitrification rate was 0.4 mg NO₃ ⁻-N/g MLSS h. Nitrogen removal was conducted with continuous feed inflow and with intermittent aeration with a different duration of aeration and non-aeration phases. The best results in the experiment were achieved when the aeration regime was set to 60 minutes aeration and 120 minutes without aeration, resulting in the reduction of total nitrogen from 45 mg/L to about 12 mg/L. In the second bioreactor, with a hollow fibre membrane, specific nitrification rate during batch nitrification amounted to 1.21 to 1.48 NO₃ ⁻-N /g MLSS h. When all of the glucose was added at the start of the experiment, the specific denitrification rate ranged from 2.75 to 3.15 NO₃ ⁻-N/g MLSS h. The best nitrogen removal in the experiment, amounting to 90%, was achieved with a continuous feed inflow and with the intermittent aeration regime set to 60 minutes of aeration and 120 minutes without aeration, with a glucose concentration in feed water of 0.72 g/L.

Keywords:

• MBR
• Nitrification
• Denitrification
• Intermittent aeration