BIOPAQ® AFR, the Anaerobic Flotation Reactor, is especially developed for the anaerobic treatment of waste streams that contain FOG (fat, oil, grease) and/or biodegradable solids like proteins and starch. It fills the long-existing gap between high rate anaerobic reactors and digesters.

BIOPAQ® AFR is an all-in-one reactor concept that converts all organic compounds - including FOG and biodegradable solids - into valuable biogas. It can handle water streams with COD levels up to ~100 g/l. The integrated flotation unit ensures that biomass and not yet converted compounds are retained in the reactor, whereas biogas and purified water are extracted from the reactor.



Advantages of the BIOPAQ® AFR
• considerable reduction in discharge cost (COD removal in most cases 90-95%)
• production of valuable biogas
• no pre-treatment needed to remove fats and proteins: no polymer cost for flocculation and no discharge costs for discharging fat- and protein sludge
• no pre-acidification tank needed
• compact reactor: hydraulic retention time is 1,5 to 8 days (in comparison with digester technology: 20-30 days)
• very low level of solids in the effluent: no decanter needed as effluent post treatment
• no odour emission due to closed reactor design

Working principle
The basic principle of the BIOPAQ® AFR is that biodegradable solids and FOG will remain within the reactor until they are digested to biogas, while at the same time the retention time of the water is kept to a minimum.

This is achieved by integrating a flotation unit within de reactor. In this unit, solids and fats are floated with the help of biogas (so-called 'white water') and the flotation layer is sent back into the reactor to be digested. The effluent is extracted from beneath the flotation layer and contains virtually no solids. The generated biogas leaves the reactor from the top.

The application of an integrated flotation unit results in high sludge concentrations and a long sludge retention time. The hydraulic retention time on the other hand is very short: therefore the reactor design is very compact.