In MBBR and IFAS technologies, it is of utmost importance to have good media distribution. The fact that the media are rather 'discrete' units poses difficulties with the mixing.

We have two different in-house models for carrier simulation at full-scale, both in aerated and non-aerated basins at full-scale. We evaluate different design and operational conditions such as:

• Media type and filling degree
• Inlet and outlet configuration, including grid openings
• Aerator placement (if aerated)
• Mixers (if mixers installed)
• High and low flow rates

Using the CFD model, we virtually optimise the design to prevent operational issues that are costly to fix afterwards. We hence work at 2-phase (water/carriers) and 3-phase (water/air/carriers).