As a hybrid Reactor with fixed film (packed bed) and suspended biomass the ANAFIX is used for specific effluents, e.g. (petro) chemical industries wastes, when granular sludge development is difficult.

Main advantages of the ANAFIX™ are:

  • Stable operation even with e.g. higher sulfate and inert suspended solids concentrations.
  • Can handle more distinct variations in flow and load

Disadvantage of the packed bed is a higher risk of blockage of the carrier material when utilized for wastewaters with high calcium content.

The wastewater enters the methane reactor at the bottom through a special distribution system with integrated back-wash possibilities.

On the way up the wastewater is treated passing consecutively through the sludge blanket and a layer of carrier material with fixed film biomass.

The sludge layer is typically 1-2m high and sometimes adopts an almost granular structure.  Hydrolysis and removal of a substantial part of the COD takes place in this layer.

All remaining COD is taken care of by the fixed film biomass on the polypropylene carrier material.

Apart from the creation of a substantial surface area, on which acetogenic and methanogenic bacteria find their preferred habitat, the polypropylene carrier material is positioned to allow a proper gas passage and to ensure retention of even the finest sludge flocs.

At the top of the methane reactor, the clean effluent leaves the system through a series of overflow channels and pipes.

In order to avoid sludge washout with the effluent, excess sludge is removed from time to time from the bottom of the reactor. Biogas is collected at the top.