LIFE SludgeisBiofuel - Dryer for energy recovery from sewage sludge and manure

LIFE12 ENV/SE/000359

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Contact details:

Contact person: Robert JOHANSSON
Tel: 4691087600
Email: robert.johansson@outotec.com

Project description:


Biomass waste such as sewage sludge and manure can be processed to extract energy and phosphates. The first stage is the production of biogas through processes of anaerobic digestion - the breakdown of organic matter in the absence of oxygen. This leaves a sludge which still contains up to 50% of the available energy.

This remaining energy can be extracted through incineration to produce both energy and an ash from which phosphates can be recovered. However, before incineration can take place, the sludge needs to be dried to reduce its high water content – 80-97%. Unfortunately, given current techniques, more energy needs to be consumed to dry the sludge than would be extracted through its incineration.

A more efficient drying method could release the tremendous potential of biomass waste for energy recovery and phosphate recycling. Sweden alone produces 214 000 dry tonnes/yr of sewage sludge from municipal wastewater treatment, representing some3 TWh/yr of potential energy.


LIFE SludgeisBiofuel aims to demonstrate an energy-efficient method for drying waste biomass ready for incineration processes to recover energy and phosphates. It plans to develop a new application of an existing industrial drying process. It thus hopes to contribute to a greater valorisation of biomass, contribute to the EU’s long-term goals around renewable energy and improve management of phosphates throughout their lifecycle.

The project is taking as its basis a process that has been effectively used to dry wood and peat for some 15 years. Developed by Skellefteå Kraft AB, this process will be reviewed and developed by the beneficiary to create a concept for industrial drying of biomass sludge.

The project will build a pilot plant for sewage, manure and digestion residues at Skellefteå's municipal sewage treatment plant. Here it will test the adapted drying technology and review, adapt and optimise the process. It hopes to reduce by one quarter the energy required for evaporating water off the residue.

The project thus hopes to show that the energy needed to dry the biomass is less than the energy that can be extracted from the dried biomass through incineration, thereby demonstrating the commercial feasibility of full-scale plants for drying biomass residues as part of a broader process of recovery of energy and phosphates. The positive energy balance should create the incentives to make this a widespread practice, contributing to wider renewable energy goals.

Expected results: The project expects to achieve the following results:

  • Reduce the energy consumption for drying sewage sludge, manure and digestion residues from 800 to 200 kWh/tonne of (evaporated) water;
  • Achieve 100% energy recovery from biogas – up from current rates of below 50%;
  • Enable more energy to be generated from the biomass than is consumed in the treatment process – a positive energy balance;
  • Demonstrate commercial feasibility of a full-scale process for energy recovery from biomass waste;
  • Contribute to achieving renewable energy goals;
  • Successfully extract phosphates from the ash produced by incineration of dry biomass for valorisation as fertiliser; and
  • Reduce the amount of unvalorised biomass waste and associated risks of (nutrient) pollution of soils and waters.



Environmental issues addressed:


Waste - Waste recycling


use of waste as energy source‚  manure‚  sewage sludge

Natura 2000 sites

Not applicable



Coordinator Outotec (Sweden) AB
Type of organisation International enterprise
Description Outotec is a private company that specialises in minerals and metals processing technology. The company also provides innovative solutions for industrial water treatment, the use of alternative energy sources and the chemical industry.
Partners None


Project reference LIFE12 ENV/SE/000359
Duration 01-JUL-2013 to 30-JUN -2016
Total budget 3,063,115.00 €
EU contribution 1,250,000.00 €
Project location Övre Norrland(Sverige)


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