AECO-FAT - Fat Recovery

Fat recovery from industrial wastewater as biofuel

Dissolved air flotation (DAF) is often applied to treat industrial wastewater containing high oil & grease by which TSS removal of 45-70% and oil & grease removal of 50-80% can be achieved without chemicals.

However, fat which is part of the dry matter constituent in the sludge, is often neglected, even though it has high potential as an economically valuable resource such as heating fuel, biofuel, cosmetics, and/or co-substrate for anaerobic digestion.

How can fat be recovered from the wastewater?

Fat can be recovered with Nijhuis AECO-FAT, a total sludge management solution including a dissolved air flotation unit, followed by a disconnector and separation into a liquid fat, a water and a solids fraction. This way an economical value has been added to the recovered product.

With the recovery of fat, the Nijhuis AECO-FAT solution converts flotation sludge into valuable products and saves sludge disposal and chemical costs.

As sludge minimization is a very important concept in wastewater treatment, we developed several profitable business cases based on the incoming and outgoing requirements, operational costs and capital investment costs.

  • Dew-Valley


  • Sugar-Creek

Why Nijhuis AECO-FAT?

AECO-FAT is a robust, proven technology which amongst others achieves the following benefits:

  • Saving sludge disposal costs
  • Saving chemical costs due to less chemicals requirement for (existing) physical/chemical treatment of WWTP
  • Solids from fat separator can be used as biosolids
  • Highly automated system in smart configuration
  • Saving fuel costs
  • Create value with the produced fat, for example:

- Biofuel
- (Heating) fuel
- Cosmetics
- Co-substrate for anaerobic digestion

  • Highest possible centrate quality after fat separation, hence low loading into the existing WWTP

What is flotation sludge?

Flotation sludge is a mixture of water, solids and fat. When treating wastewater, primary treatment is needed to reduce the solids and fat content in the water.

Course solids can be filtered from the water by using the Nijhuis patented NTF rotating filter or Nijhuis Aquarake. Fats passing through the filter together with the water can be separated by the unique and reliable Nijhuis DAF systems which will generate flotation-sludge.

How to separate flotation sludge?

After the DAF system, heating is the first step in the process where all the fat is liquefied. The second and third step are to separate the solids and water. Separation techniques such as a tricanter are required to guarantee a thorough separation of all three phases and substantially increase the yield of fat.

How to add value from the recovered fat?

The separated water will flow back to the wastewater treatment plant, whereas the separated solids-proteins can be utilized as fertilizer.

The separated fat obtained can be used for various value-added purposes such as fuel for steam boilers or biofuel. The fat is also a trade-commodity with a high value.

Where can Nijhuis AECO-FAT be applied?

Nijhuis AECO-FAT can be applied to typical wastewaters containing high concentrations of fat including wastewaters of slaughterhouses, protein processing plants (like bacon) and confectionary plants.

Depending on consumables costs, an average payback period for an AECOFAT solution of two years can be achieved.