Orange peels, olive pulp, paper sludge: filtration not only provides filtered liquids, but also sludge. This is often valuable material and it would be a shame if it just ends up on the waste heap. TNO Energy Transition, part of the well-known TNO research institute, has therefore developed a method to convert waste sludge into useful residual products: the patented technology TORWASH®.
In 2019 TNO approached Limburg Filter to ask whether we want to help optimise sludge dewatering into filter cake. In a pilot at the WWTP Almere of the Zuiderzeeland Water Board, we pressed all the necessary buttons until we found the right combination of filter cloth and process. The results were so positive that they led to a strategic collaboration between TNO and our company.
After the slurry has been dewatered, the filter cake is further dried and processed into pellets. Combustion then turns it into energy. The process is an almost closed cycle. Due to the optimised filtration, a lot of clean water is released and the solid matter that remains has a high heating value.
Both partners in the F-Cubed consortium are now working with European companies and knowledge institutes on upscaling this promising technology. The project is sponsored by the European Union and will soon travel through Europe as a sort of mobile factory. Ultimately, the technology must be used for the processing of industrial waste flows.
The first stop of this European tour was the Smurfit Kappa paper mill in Sweden. Together with TNO, Limburg Filter has helped to process paper sludge, a waste product. Paper sludge is first treated in the Torwash reactor, then dewatered using our filter press to a filter cake.
In Italy, we helped TNO set up a similar process for an olive oil cooperative. Filter cakes have also been produced there using our filter press. We are proud of the good cooperation with TNO and all other partners in the consortium.