MBBR™ biofilm technology
An introduction to biofilm wastewater treatment
When communities of microorganisms grow on surfaces, they are called biofilms. Microorganisms in a biofilm wastewater treatment process are more resilient to process disturbances compared to other types of biological treatment processes. Thus, biofilm wastewater treatment technologies can be considerably more robust especially when compared to conventional technologies like activated sludge.
The very first biofilm process, the trickling filter, was invented towards the end of the 19th century. The trickling filter can be reliable and stable but does suffer from one serious drawback; it easily becomes clogged and septic even under moderate loading conditions.
In the MBBR™ biofilm technology the biofilm grows protected within engineered plastic carriers, which are carefully designed with high internal surface area. These biofilm carriers are suspended and thoroughly mixed throughout the water phase. With this technology it is possible to handle extremely high loading conditions without any problems of clogging, and treat industrial and municipal wastewater on a relatively small footprint.
The MBBR™ biofilm technology is efficient, compact and easy to operate. It can be an excellent solution as a stand-alone process, a Moving Bed™ biofilm reactor, or it can be used to specifically enhance or upgrade treatment potential of activated sludge processes. The MBBR™ biofilm technology can be used as a preliminary treatment stage (BAS™), as a combined IFAS hybrid stage (HYBAS™) and as final a polishing step (LagoonGuard™).
System description
The MBBR™ biofilm technology is based on specially designed plastic biofilm carriers or biocarriers that are suspended and in continuous movement within a tank or reactor of specified volume. The design of associated aerators, grids, sieves, spray nozzles and other integral parts to the reactor is also of great importance in making up the system as a whole, which is what AnoxKaldnes is marketing .
The industrial and municipal wastewater is led to the MBBR™ treatment reactor where biofilm, growing within the internal structures of the biocarriers, degrade the pollutants. These pollutants that need to be removed in order to treat the wastewater are food or substrate for growth of the biofilm. The biocarrier design is critical due to requirements for good mass transfer of substrate and oxygen to the microorganisms and there is a continuous R&D in the area of the MBBR™ biofilm technology . Excess biofilm sloughs off the biocarrier in a natural way .
An aeration grid located at the bottom of the reactor supplies oxygen to the biofilm along with the mixing energy required to keep the biocarriers suspended and completely mix within the reactor.
Treated water flows from reactor through a grid or a sieve, which retains the MBBR™ biocarriers in the reactor. Depending on the wastewater, the reactors are may be equipped with special spray nozzles that prevent excessive foam formation.
BioCarriers
AnoxKaldnes has developed a complete range of MBBR™ biocarriers to suite different processes and wastewaters. The different models we offer are:
| Model | Length (mm) |
Diameter (mm) |
Protected surface (m²/m³) |
Total surface (m²/m³) |
|---|---|---|---|---|
| K1 | 7 | 9 | 500 | 800 |
| K3 | 12 | 25 | 500 | 600 |
| Natrix C2 | 30 | 36 | 220 | 265 |
| Natrix M2 | 50 | 64 | 200 | 230 |
| Biofilm-Chip M | 2,2 | 48 | 1200 | 1400 |
| Biofilm-Chip P | 3,0 | 45 | 900 | 990 |