Measure microbial activity driven oxygen transfer in membrane aerated biofilm reactor from supply side

Rongfen Chen^a,b, Yan Zhou^b,c

Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, 639798, Singapore.

Abstract

This short communication demonstrates for the first time a solely microbial activity driven oxygen influx across a microporous hollow fibre membrane via tracking changes in volume and gas composition of entrapped air supply. A U-shape manometer was used to directly reflect gas influx due to microbial activities. A pressure difference of several hundred pascal was created to draw oxygen while 25 mg-N/L of ammonium was oxidized into nitrite by active biofilm at a hydraulic retention time of 6 h. Calibrated and normalized gas compositions before and after the experiment were processed to unveil the gas exchange and estimate the actual oxygen influx across the membrane. A solely microbial activity driven oxygen influx of 10.7 mg O2/m2/h was observed. Measuring oxygen transfer from supply side provides a more straight-forward perspective on the role of active biofilm in membrane aerated biofilm reactor. The capability of the microbial activity to uptake oxygen on its own could potentially lead to greater energy savings in some MABR applications when strict aeration control is not needed.

Keywords: Oxygen transfer rate, Membrane aerated biofilm reactor, Microbial activity driven oxygen transfer.