**3.2 Bioreactor set-up**

The Air Micro-Bubble Bioreactor (AMBB) with a total volume of 15 dm3 consists of a cylindrical bioreactor, equipped with a circulated pump and a settler (Figure 15). The aeration was conducted during the wastewater recirculation by a high efficiency Venturi injector (HEVI) in conjunction with mass transfer multiplier nozzles (MTM). The MTM nozzles discharge the air/water mixture from the HEVI into the bottom of the bioreactor (Figure 14). The AMBB is equipped with an air flow meter and a monitoring probe (HANNA Instruments) able to on-line monitor pH, DO and temperature. Figure 16 shows a schematic overview of the bioreactor.
