Aquabiotec Engineering SARL

Biofiltration, Advanced Treatment

The Aerated Upflow Biological Filtration (Biofilter) represents a biological treatment with fixed film biomass. Biological treatment and filtration of suspended solids take place in one and the same tank.

The biological upflow filtration is particularly suitable to eliminate carbon, ammonium, nitrogen and phosphorus. In the same time, an advanced removal of suspended solids is achieved. A process air diffuser below the strainer plate distributes the oxygen needed for the oxidation of carbon and ammonium.

New developments provide a modified economic wastewater and air distribution system with modular biofilters. The modular design of biofilters simplifies possible later upgrading. An equal oxygen supply on the total filter cross-section must be assured. Denitrification (mainly for municipal wastewater treatment) can be achieved by recirculation or by injection of external carbon source such as raw sewage or methanol.

Biofilters are adapted for biological treatment of low concentrated paper mill wastewaters, i.e. up to about 80-100 mg/l BOD as single stage plants after chemical-mechanical pretreatment. For BOD concentrations below about 80-100 mg/l at one stage biofilter can be used. A two-stage biofiltration (same number of biofilter units in each stage operated in parallel) is used for wastewater up to about 200 mg/l BOD.