Technical Details
AnoxKaldnes™ MBBR Technology
The aerated MBBR uses, as the activated sludge process, the whole volume of an open tank. It is defined as a biofilm system, as the biomass is growing on carriers that move freely within the reactor volume and are kept within the reactors by a sieve at the reactor outlet. The system can be used either for aerobic or anoxic processes. In aerobic processes the biofilm carriers are kept in suspension by the agitation created by air from aeration diffusers, while in anoxic processes a mixer keep the carriers in movement. A schematic of the principle in an implementation of the AnoxKaldnes™ MBBR technology is shown below (Figure 1).
Figure 1: Schematic showing the principle of the MBBR
A medium bubble aeration system has been especially developed for the MBBR reactor by AnoxKaldnes. With the presence of the carriers the efficiency of the aeration system is improved and comparable with that of a fine bubble aeration system.
The outlet sieve or grid has a design that depends on the type of carrier chosen, the hydraulic load and whether the reactor is mixed by aeration or mixers. For aerated reactors the sieves are cylindrically shaped and horizontally mounted when carriers type K1, K3 and BiofilmChip™ P and M are used. When the bigger carrier F3 is used, a grid keeps the carriers in the reactor. In the anoxic reactors where carriers type K1 are used the outlet sieves are vertically mounted and rectangular. In all cases the outlet sieves or grids are equipped with aeration to keep them from clogging.
Figures 2: Pictures of AnoxKaldnes aeration system (above to the left) and examples of outlet sieve installations (cylindrical horizontally mounted above to the right and a grid below to the left). Below to the right a vertically mounted sieve and mixers from an anoxic reactor is shown.
