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Solution Provider


AquaGreen ApS

AquaGreen ApS

About AquaGreen ApS

AquaGreen is a cleantech engineering company that develop new and innovative solutions for wastewater sludge treatment, and for converting low-grade biomass into thermal energy and biochar or activated carbon.


Founded: 2016

Employees: 11-50

HQ: Roskilde, Denmark

Organisation type: Company


Bio-based circular solutions


Carbon capture, storage and utilisation

District heating

Drinking water treatment


Our solution integrates superheated Steam Drying and Pyrolysis in an energy efficient process.
The calorific content of the sludge is utilised for drying and converting wastewater sludge into biochar and thermal energy. The thermal energy is recoverable and can be used for district or process heating purposes. The residual biochar is rich in plant-available phosphorus and is suitable as an agricultural fertiliser.

Development of the technology has taken place in a close collaboration with the Danish Technical University. The technology is being commercialized by mid-2021 at 2 danish municipal wastewater treatment plants and is ready for broad commercialization.

Each of these units treat sludge from 50.000 people and deliver the following benefits:

  • No micro-pollutants in soil and ground water
  • No malodor or health risks
  • 10 x less transport

Supports meeting climate targets saving Greenhouse Gas emissions, storing CO2e and producing energy:

  • Total saved emissions:                                               1800 tons CO2e reduction1
  • Carbon storage in biochar:                                          500 tons CO2e storage
  • 2000 MWh renewable energy produced:        1500 tons CO2e reduction2

Safeguard our grandchildren’s food supply by recirculating Phosphorus to the soil.

  • 25 tons life critical Phosphorus re-circulated

The investment has an attractive pay-back time as the current biomass/sludge handling cost will be converted to an income from selling renewable energy and carbon- and carbon removal credits.

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