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News | 2021-06-02
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The Margretelund wastewater treatment plant. Photo: Roslagsvatten

New sludge management technology tested in wastewater treatment plants

Roslagsvatten has initiated a collaboration with environmental technology company C-Green and IVL Swedish Environmental Research Institute with the goal of constructing a “sludge-free” wastewater treatment plant. A new method means that sludge will no longer be one of the end products at the Roslagsvatten Margretelund facility outside Stockholm.

– C-Green’s sludge management technology is fully in line with our vision of integrating sustainable solutions into the services we offer. IVL’s research and expertise in this field will provide us with invaluable assistance when it comes to developing wastewater treatment worldwide. My staff and I are extremely proud of our efforts in this regard, says Christian Wiklund, Roslagsvatten’s CEO.

Pilot trials will commence this autumn, wet sludge will be processed on site and converted into a solid carbon-enriched product, HTC biochar, using a technology developed by C-Green. The resulting HTC biochar can be spread on arable land, used as soil improver or as biofuel.

The method will deliver several environmental and climate benefits, among these it is estimated that the need for truck transports to and from the treatment plant will be reduced by 75 per cent. It will no longer necessary to store sludge in depots, which means that greenhouse gas emissions are expected to decrease by around 80 per cent compared with current sludge management practices. Another advantage is that unpleasant and offensive sludge odours will disappear.

– The project is a pilot investigation to ascertain whether the proposed system solution can function as a sustainable alternative for future sludge management at Swedish treatment plants – reducing climate impact, cutting nutrient emissions to the environment, and recirculating vital resources extracted from wastewater to agriculture, says Christian Baresel, project manager at IVL Swedish Environmental Research Institute.

IVL, which operates the Hammarby Sjöstadsverk research facility, has for several years been working to develop sustainable sludge management techniques. C-Green and IVL have been engaged in a collaborative effort since 2015, investigating current technology and exploring numerous avenues that have now resulted in a further step. In the current project, financed by the IVL Foundation, Roslagsvatten and C-Green, IVL will primarily test different purification techniques which will be applied the process water that is a result of this treatment.

– Collaboration between Roslagsvatten and IVL is a major step towards further adapting sludge management in sludge treatment plants, especially in view of the reduced climate impact this leverages. Each tonne of sludge can generate 200 kg of greenhouse gases emissions or more. Our process makes it possible to bypass sludge completely, carbon is instead captured in an innovative and beneficial product, says Erik Odén, CEO at C-Green.

The final goal of the project is the construction of a full-scale plant at the Roslagsvatten’s Margretelund facility. Today, C-Green’s pulp sludge technology is already utilized at a large-scale plant at Stora Enso in Finland.

For more information, please contact:
Christian Baresel, christian.baresel@ivl.se, +46 (0)10-788 66 06

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