It is on the surface of the bio media in a bio filter that the mineralization of the remaining organic matter from the preceding solids removal takes place and the oxidation of ammonia/ammonium (TAN). 

In an aquaculture situation, it is TAN that is our target compound, unlike some other wastewater types, for instance municipal wastewater where it is organic matter that is the target compound. This means that in a RAS bio filter we have to create as good conditions as possible for the nitrifying bacteria. This is even more evident, as, the concentrations of TAN we are operating at in an aquaculture situation, i.e. from maybe 0.5 – 2.00 mg/l, are in themselves limiting for nitrification ratios. For that reason alone, we have to eliminate as many other limiting factors as possible. One obvious thing is to avoid oxygen diffusion limitations through the bio film, i.e. we have to ensure it doesn’t build up excessively.

With MBBR and especially the Clearwater MBBR© concept, we avoid oxygen limitations in the bio film by having the most optimum movement of the bio media and we achieve what is termed Bio Film Control (BFC). With the latest research in bio film kinetics, BFC is the most important aspect of bio filter function. At IAA we have further enhanced the conditions for the bio film and the nitrifying bacteria with the new CURLER© bio media. The most important feature of the CURLER© bio media is its open profile. If one has protected areas, one creates excessive bio film build up, even clogging can occur in the protected areas and all the benefits of MBBR are compromised. This can and does not happen with the CURLER© bio media. With the Clearwater MBBR© together with the CURLER© bio media we have the best performing bioreactor concept on the market.