NITRIFICATION IN A BUBBLELESS OXYGEN MASS-TRANSFER MEMBRANE BIOREACTOR

Two laboratory scale biological reactors with hollow fibre incorporate d to provide bubbleless aeration to a biofilm attached to the membrane wall were investigated during the nitrification of a synthetic wastew ater high in ammonia (30-50 mg l(-1)). Pure oxygen on the lumen side o f the fibres was transported through the pores of the membrane wall di rectly to the biofilm without the formation of bubbles. As a consequen ce oxygen usage efficiency is significantly increased. During the 51 d investigation the volumetric nitrogen loading rate increased from 0.0 8 to 0.20 kg NH4-N m(-3) d(-1). At the highest loading rare nitrificat ion rates approaching 0.20 kg NH4-N m(-3) d(-1) were achieved. The dis solved oxygen concentration in the bulk liquid phase stayed well above critical. Hollow-fibre bubbleless oxygen mass transfer membrane biore actors (MBR) show promise in providing a small-footprint alternative t o conventional tertiary nitrification processes. Copyright (C) 1996 IA WQ. Published by Elsevier Science Ltd.