Sludge is a by-product of sewage treatment with often untapped potential for resource recovery. In 2020, a group of students from Wageningen University & Research investigated sustainable sludge management options in the Netherlands. The research topic was commissioned by the Netherlands Water Partnership (NWP) under the framework of the Partners for Water Programme.
The main findings of the research are now available in a summary report. The summary is being used to initiate and foster collaboration between the Dutch and Western Balkan water sectors. At present, the countries in the Balkan region are expanding their sewer networks and increasing the number of sewage treatment plants, which will lead to increased amounts of sludge that need to be effectively managed. There is a pressing need to explore sustainable solutions for sewage and sludge management that can be adapted to the context of the region.
Wastewater treatment coverage in the Netherlands has been almost 100% since 2008, with around 350 sewage treatment plants. In the year 2016, approximately 345 thousand tons of sludge were produced in the country. In the Netherlands, the concept of transforming WWTPs into “Energy and Resources Factories” is being implemented. The transformation is led by a team of employees from water authorities that want to contribute to the transition of wastewater treatment to the recovery and reuse of energy and raw materials. Examples of recovered materials are cellulose, nutrients, bioplastics, fatty acids, Kaumera gum, water, biomass, and energy. Over the years, the Dutch water sector has been developing innovative sludge treatment techniques and has become a leader in implementing resource recovery. According to largest Dutch sludge treatment company SNB, over 95% of sludge treatment residues were employed as reusable raw materials.