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Biogas generated from fat containing waste streams

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Biogas generated from fat containing waste streams
Bio-digester produces energy from fat-containing waste water.
In Use – The current Unilever project will be one of the first installation worldwide to use this type of bio-digester in a food manufacturing facility.


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The basic principle of the bio-digester is that biodegradable solids and FOG (fats, oils and grease) 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 the 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.
The BIOFAQ AFR (Anaerobic Flotation Reactor) from Paques is an all-in-one reactor that converts all organic compounds - including fat, oil and grease and biodegradable solids like proteins and starch - into valuable biogas. It can handle water streams with COD levels up to 100g/l. An 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. It fills the long-existing gap between high rate anaerobic reactors and digestors. Paques claims its BIOPAQ AFR is “unique” in the field of purification of fat-containing wastewater. This is because wastewater streams that contain fat and oil are treated and digested in one compact reactor, together with degradable particles, whereas in conventional systems this is only possible by going through a number of processing stages.
Unilever has installed a bio-digester to convert natural waste products into a bio-gas to generate "green energy" at its Ben & Jerry's Ice Cream factory in Hellendoorn, Netherlands. The BIOFAQ AFR from Paques became operational during the second half of 2011. Unilever also plans to install similar digesters at its other plants. Paques claims that other food manufacturers are also interested in this digestor technology, but that Unilever are one of the first companies world-wide to use this type of bio-digestor.
The content in this entry has been obtained from publicly available information sources only (e.g. press releases, website and trade press articles) and is subject to completion of a validation process with the technology supplier.

Potential Benefits

It is anticipated that the reactor will generate up to 40% of the Hellendoorn factory's targeted green energy requirements. Paques also lists the main operational advantages of the system:
  • 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.

Intellectual Property

This particular installation is the proprietary technology of Paques.

Consultant View

There are numerous providers of bio-digester technology. Interested readers should search the Internet for alternative suppliers.
Readers are also encouraged to look within REID for other technologies with similar objectives. Try using the filters and key word search facility to view other process related technologies.

Contacts and Further Information

Company details:
Paques bv
Postal address:
P.O. Box 52
8560 AB BALK
The Netherlands
Visiting address:
T. de Boerstraat 24
8561 EL BALK
The Netherlands
Tel: +31 514 608500

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