A Pilot Scale Evaluation of Membrane Aerated Biofilm Reactor technology for BNR Process Intensification

The MABR is a promising biological nutrient removal intensification technology. In an MABR oxygen is delivered to a biofilm growing on the outside of membrane surface by diffusion through the membrane wall (Figure 1). The substrate is delivered from the opposite direction from the bulk liquid (or mixed liquor) into the biofilm. The introduction of oxygen and substrate from opposite directions into the biofilm results in a so-called counter-diffusional biofilm. Oxygen is consumed within the biofilm with minimal transfer to the bulk liquid. Indeed, effective control of the air flow rate into the lumen and therefore the supply of oxygen supply into the biofilm theoretically results in a biofilm with an aerobic biofilm layer adjacent to the lumen and an unaerated biofilm layer adjacent to the bulk liquid (as illustrated in Figure 1). When an MABR is placed in an anoxic zone of a suspended growth bioreactor, ammonia diffuses into the aerobic biofilm layer promoting nitrification. The nitrate (and any nitrite) produced through nitrification diffuses towards the bulk liquid and denitrification occurs in the unaerated (here anoxic) biofilm layer. As a result, the use of an MABR enables efficient simultaneous nitrification-denitrification within the biofilm when the bulk liquid surrounding the MABR is anoxic. In this way, a hybrid MABR-suspended growth system can be used as an intensified Biological Nutrient Removal (BNR) process. While the concept and principles of an MABR process have been extensively evaluated at the lab-scale for over three decades, commercially available MABR technologies are relatively recent (Martin and Nerenberg, 2012). Our research aims to evaluate MABRs in real-world applications under a wide range of influent and operating conditions treating primary effluent.