Principles for the Dimensioning of Fluidized- Bed-Reactors
The dimensioning of the Biofilm Process is essentially influenced by the desired degree of wastewater treatment. The permissible treatment objectiv is dependent on the surface loading.
Dependent on the shape of the carrier material different usable surfaces result even with the same specific surfaces. The performance details attributed to the specific surfaces and the therefrom derived dimensioning recommendations can, as a result, apply only with the limitation that, if necessary, correction values are to be taken into account. This applies in particular for the respectively given specific surfaces of the carriers with different diameters. Of particular significance for the performance of the Biofilm Process is the oxygen transfer and the oxygen partial pressure. The selected oxygen content cx in the aeration basin may be higher than for the Activated Sludge Process. The cx - value for plants with nitrification are recommended to 6 ... 8 mg/l, for plants with nitrification and simultaneous denitrification 0,5 mg/l in the past stage or with circulation tanks.
The sludge production is a significant factor for the operating costs of wastewater treatment plants. For both the dimensioning of the sludge treatment stage and for the operation of the plant, the amount of surplus sludge to be removed is of some interest. The specific sludge production for Biofilm Process is match lower than for Activated Sludge Process. The surplus sludge production SSBOD5 dependent on surface loading and the ratio DS0 to BOD5 in the inflow to the aeration tank can be taken from the following table:
