Solids and Hydraulic Retention Time Effect on N₂O Emission from Moving‐Bed Membrane Bioreactors

Abstract

Biological nutrient removal was operated at different solids (SRT) and hydraulic retention times (HRT) in order to assess their influence on nitrous oxide (N 2 O) emission from a hybrid moving-bed membrane bioreactor. The observed results show that the N 2 O production decreased when the SRT/HRT was decreased. The maximum N 2 O gaseous concentration was measured in the aerobic reactor at the end of phase I, and it decreased through phases II and III. From mass balances over the reactors of the system, the aerated (aerobic and membrane) reactors were the largest producers of N 2 O, showing that the greater part of N 2 O was produced during the nitrification process.