The EffiSludge concept

An efficient wastewater treatment with reduced foot print and energy demand, recirculation of nutrients and sustainable use of the excess sludge is possible under EffiSludge condition.

By integrating an anaerobic digestion process within the existing  wastewater treatment, EffiSludge for LIFE aims to reduce overall carbon emissions linked to energy and chemical  usage for the processing of the wastewater. Furthermore, modifing operational aspects of the aerobic step, the project aim to increase  digestability of biosludge, also called waste activated sludge (WAS). The produced biosludge will be used as a substrate for biomethane production trough anaerobic digestion. Part of the residue from this process, the rejected water fraction, will in turn provide nutrients needed by the aerobic step, thus by recirculation replacing 100% of the current external dosing of nitrogen (urea) as well as the main part of the phosphorus (phosphoric acid) demand.

Wastewater treatment

Norske Skog Skogn has an onsite wastewater treatment plant processing ca. 20 000 m3 per day. The wastewater treatment process counts on a primary sedimentation unit followed by a conventional waste activated sludge system that guarantees 95% total COD removal and 98% suspended solid (SS) removal. Conventionally, primary sludge and waste activated sludge (WAS) are dewatered together and process for energy recovery via incineration.

The current wastewater treatment will be upgraded to support EffiSludge condition. From spring 2017 a sampling campaign monitored the status of the plant providing fundamental reference data for the project. Since 2019, a Upflow Anaerobic Sludge Blanket (UASB) reactor, is in operation processing part of the process water from the mill prior the aerobic step (Activated Sludge Treatment).

Why EffiSludge?

Save carbon emissions for a better planet.

The pulp and paper industry ranks fourth in terms of energy consumption among industries worldwide. Globally, this industry accounted for approximately 5% of the total industrial final energy consumption. A part from the high energy consumption for pulp and paper production also results in liquid and solid wastes, air emissions, and wastewater. Due to the high energy intensity the EU has acknowledged that the Pulp and Paper Industry has a strategic role to play in climate change mitigation. At the same time the worldwide pulp and paper demand and production are projected to increase significantly which will lead to an increase in this industry’s absolute energy use and greenhouse gas emissions. This development can however be counteracted by of new energy-efficiency and GHG mitigating technologies/concepts and their deployment in the market will therefore be crucial for the Pulp and Paper Industry’s mid- and long-term climate change mitigation strategies.