heat Harvest icon

With the increasing importance of renewable energy and rising interest in by-product heat utilization, Waste Treatment Technologies (WTT) has developed a technology to be able to maximize the useful thermal energy production. Massive amounts of thermal energy are generated by the composting metabolic processes, which form a huge untapped resource for bio-energy. This heat can either be used for on-site purposes and save a lot of energy by heating buildings, pre-heat process air or dry other types of products, but it can also be sold as a source of renewable energy for neighboring operations like greenhouses, factories, heating networks or other demands for hot water. Valorization of waste heat plays a valuable role in offsetting dependence on fossil fuels, reducing operating expenses and increasing productivity.

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“Re-use of heat saves our facility yearly about 900.000 cubic meters of natural gas. In addition, we have enough production to sell heat to neighboring operations. At full capacity we could save about 2 million cubic meters of natural gas.“

Pieter van den Boomen

Co-Founder Upcycling, Netherlands

WTT’s approach build on over 25 years of experience with in-vessel composting.

Together with our production partner GTL Europe, we have improved this existing technology and complemented it with specialized heat exchangers and a smart energy management system to capture all residual process heat and make it available for other processes.

Most types of organic feedstocks are suitable as a feedstock for the Heat Harvest system. Examples are: SSO, leaf and yard waste, spent mushroom compost, MSW and manure.

WTT already has experience in heating of process buildings, mushroom farms, and greenhouses. Our technology can be applied in new composting facilities, or it can be retrofitted in existing composting installations. we have over 10 reference projects in which we successfully applied this technique.

Benefits of Heat Harvest

Improved Effective
Organic Matter

Crop Yield

Sell Energy to
Neighboring Process

Reduce Water

Reduce Transport
Cost and Emissions

Free Source of
Thermal Energy

The Process

In our in-vessel composting system the feedstock is aerated and all process conditions are optimally controlled by our control system.

The composting process is managed in several phases, each of which are designed to shorten time-to-temperature and re-use and capture the available thermal energy. By running at thermophilic temperatures higher temperature heat can be captured. Depending on the type of feedstock up to 2600MJ per ton of feedstock can be captured.

Odour control

In control of odour

  • State of the art air treatment system
  • Acid scrubber to remove ammonia
  • Robust bio

Greater than 98% odour removal

Biodrying and composting
of the following feedstocks

  • Biogas Digestate
  • Sewage sludge/Biosolids
  • Poultry manure
  • Separated cow/pig manure
  • Biomass
  • Organic waste
  • Green waste
  • Food waste
  • MSW
  • Co-products from feed/food processing
Biodrying and composting

Applications for the product

The Heat Harvest system reduces water content, increases calorific value and increases organic stability and nutritional value. Depending on the type of feedstock and the intensity of the drying process the following applications of the end product are possible:

  • Quality compost
  • Peat alternative
  • Organic fertilizer
  • Biofuel with high heating value
  • RDF
  • Input for pelletizer

View Past Client Projects


Heat is supplied to neighbouring mushroom nursery and neighbouring asparagus farm.

The plant has the capacity to substitute close to 2 million m3 natural gas.

The input to this facility is 25.000t/y spent mushroom compost, with a moisture content of 70%. The electricity consumption is ca. 5kWh/ton. The output of this process is 13.000 t/y compost with a moisture content of <60%. The free thermal power that is >1.5 MW!

Learn more about our
technologies & references

For WTT Heat Harvest we join forces with GTL Europe as exclusive production partner