Veolia Water Technologies & Solutions

BioFOR Biological Reactors for Anoxic & Aerobic Water Treatment

Aerobic or anoxic process biological reactors for wastewater treatment

BioFOR filters are aerobic or anoxic process biological reactors that use attached growth technology for application in municipal or industrial wastewater treatment. The BioFOR process is used primarily for the removal of BOD, TSS and ammonia pollution in secondary and tertiary treatment.


BIOFOR Technology

The BioFOR process is used primarily for the removal of BOD, TSS and ammonia pollution in secondary and tertiary treatment. BioFOR units discharge treated water that conforms to high quality standards for every parameter thanks to the filtering action of the Biolite* filter media.

Because BioFOR is designed to treat higher organic loadings than conventional systems, the units can accommodate higher filtration velocities. The units allow treatment of soluble pollution and solids separation in one compact reactor, so no secondary clarifiers are necessary. The PLC based control system automates the filter operation.

How it Works

How BioFOR Works

The effluent to be treated enters continuously from the bottom of the reactor and is distributed over the entire filter surface area by the nozzle underdrain. The water then passes through the Biolite™ filter media which retain the suspended solids. Carbonaceous and nitrogenous pollution is eliminated through the high concentration of fixed-film biomass which is retained on the filter media during the filtration cycle.

In the aerated versions (for BOD removal and nitrification) process air is introduced continuously into the lower part of the reactor by air diffusers.

The use of a co-current upflow design helps to limit odor generation since the treated water is situated at the surface of the filter (in contact with the atmosphere), and the untreated water enters at the bottom of the filter. The number of filters in filtration service is according to the flow entering the plant. During low flow periods, off-duty filters are aerated periodically to maintain the biomass in optimum condition. Since filters can be taken out of service when not required, operating costs (due to process air production) can be reduced.

Features & Applications

BioFOR Features & Applications

Main Features

  • Upflow filtration in which feedwater flow expands the filter media leading to an even distribution of the biomass throughout the bed
  • Co-current flow of feedwater and air prevents short circuiting and also extends the length of filter run times
  • Quick adaptability to flow and load variations Exclusive nozzle floor design which allows for optimum distribution of fluids during filtration as well as wash sequences
  • Highly efficient washing system to accommodate filter bed depths up to 13 ft (4.0 m)


  • BioFOR C for BOD, COD and TSS removal
  • BioFOR N for nitrification of ammonia nitrogen
  • BioFOR C+N for simultaneous BOD removal and nitrification
  • BioFOR pre-DN for nitrate removal as a pre-denitrification step without additional carbon source
  • BioFOR post-DN for nitrate removal as a final denitrification step with carbon addition


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