26 Jan 2018

Construction will commence on Royal HaskoningDHV's first full-scale innovative Themista® sludge digestion technology plant. On 25 January, Royal HaskoningDHV and the Schieland and Krimpenerwaard Water Authority signed an implementation agreement for the Kralingseveer wastewater treatment plant. The Themista technology makes it possible to extract more energy from biomass. Both parties have already demonstrated this on a smaller scale using a pilot plant.

© Schieland and Krimpenerwaard Water Authority

Biomass, such as wastewater sludge, contains energy. The digestion of biomass produces gas. However, current digestion and biogas production methods often are not optimised. Themista®, developed alongside Ephyra® another sludge digestion technology, is a thermal pre-treatment technology focused on improving and optimising sludge digestion processes at wastewater treatment plants. It uses higher temperatures in comparison to conventional digestion plants, to result in better mixing, greater sludge breakdown (and less residual waste), greater biogas production and eliminate foam problems. Royal HaskoningDHV and the Water Authority developed the technology together with STOWA and the Zuiderzeeland Water Authority.

Agnes van Zoelen member of the Water Authority Board: "The amount of energy consumed is highest for wastewater purification. We are looking at ways of consuming less energy, as well as how to generate increased sustainable energy. Partnerships such as Themista are key to developing innovative solutions that help make the wastewater treatment process more sustainable."

In 2018, Royal HaskoningDHV will finalise the plant's design, select contractors, apply for permits and start up construction. The latest completion date is mid-2020, however, the aim is to deliver the fully tested Themista plant earlier.


Together with the Zuiderzeeland Water Authority, STOWA, Delft University of Technology and Royal HaskoningDHV, the Schieland and Krimpenerwaard Water Authority is working on developing both the Themista and Ephyra® sludge digestion technologies. This project is co-financed by the European Union’s LIFE funding instrument and a Top Sector Energy Subsidy from the Dutch Ministry of Economic Affairs.