**4. Results and discussion**

398 Mass Transfer - Advanced Aspects

Fig. 15. The air micro-bubble bioreactor filled with clean water

**1**

Air

**3**

injector; 4- Recirculation pump

Feed

Fig. 16. Flow diagram of the air micro-bubble bioreactor. 1- Bioreactor; 2- Settler; 3- *Venturi*

**4**

Recirculation

purge

Wastewater

Sludge

Air

Effluent

Sludge recirculation

**2** 
