Following successful clean-water tests at the KWR Water Research Institute in Nieuwegein, on 29 September the new CoRe pilot installation arrived at the wastewater treatment plant (WWTP) in Roermond. CoRe is an advanced treatment technology in which wastewater can be directly separated. This generates two interesting products: very clean water and a highly concentrated residue that is rich in raw materials. ‘CoRe’ stands for Concentrate, Recover & Reuse, and is seen as the next generation of wastewater treatment.
CoRe is an extremely innovative approach to the treatment of wastewater, which makes possible the efficient recovery and reuse of water and of valuable raw materials. Because the treatment technology is compact, it is easy to incorporate into existing treatment plants and can be seamlessly connected to the modular Verdygo building system at the Limburg Water Authority Company (WBL). It also facilitates decentralised treatment systems. For example, it makes it possible to remove in situ what is locally needed from the wastewater stream and to deliver the rest of the wastewater through a pressure line for further central treatment. This offers very interesting opportunities for industry and agriculture.
Water and raw material reuse
‘CoRe’ thus stands for Concentrate, Recover & Reuse. The CoRe technology involves the direct physical-chemical separation of the pollutants through an innovative combination of membrane technologies called forward osmosis and reverse osmosis. This process generates two products: crystal clear water (permeate) and a highly concentrated residue (concentrate). The clean water is actually so pure that one cannot drink it: minerals have to be added to it first. For the time being, however, the application is not being used to produce drinking water, but the water can be directly used in other applications, for instance in agriculture or industry. In agriculture it offers possible means of offsetting periods of extreme drought, like those of last summer. While the water’s high quality actually makes it perfectly suited for use as process water in industry; as feed water for steam boilers or makeup water for cooling water systems, for example. The highly concentrated residue (concentrate) contains all kinds of organic material (energy), raw materials and nutrients (nitrogen and phosphorus). Also, practically all of the micropollutants are retained in the concentrate. Because of its relatively small volume and high concentration, the concentrate can be treated far more efficiently than in the case of traditional biological treatment methods. Think, for instance, of fermentation, nutrient recovery and the removal of micropollutants.
The innovative combination of forward osmosis and reverse osmosis membrane technologies forms the basis of the CoRe technology. In the first step (forward osmosis), the water is extracted through a membrane from the raw wastewater using a strong (salt) draw solution. In the second step, the salt solution is then forced under high pressure through a membrane to recover the water. The remaining concentrate can be biologically treated with anaerobic technology, which produces biogas. It is also expected that the recovery of nutrients from the concentrate stream will become more efficient. In the traditional biological treatment method, which is currently applied in all the Limburg WWTPs, bacteria are used to transform the pollutants microbiologically into nitrogen gas and CO2 . The process also releases a small quantity of nitrous oxide (laughing gas). It is expected that treatment with CoRe technologies will release fewer greenhouse gases. Treatment with CoRe thus also helps reduce greenhouse gas emissions during the treatment process. And there is another big benefit: CoRe is far more effective at removing pharmaceutical residues from the wastewater. The removal of these residues presents a huge challenge for biological treatment methods, because bacteria are not capable of removing them completely. As a result, pharmaceutical residues currently end up in surface water via the WWTP effluent.
The CoRe technology is strategically important for the future development of the wastewater cycle, and constitutes a major step towards making WBL climate-neutral and circular. The concept presents many opportunities, both in terms of water quality (very clean water for nature, or reuse in agriculture or industry), and of sustainability (smaller climate footprint, combined with energy and resource recovery). These aspects, along with a compact, modular installation, offer unprecedented added value for the future.
In 2017, the CoRe technology was tested on a smaller scale at the WWTP in Simpelveld. The first pilot installation was tested at this site for the treatment of 200 l/h; the installation in Roermond is a more developed version with a capacity of 2 m³/h (scaled up by a factor of 10). The pilot itself focuses only on the concentration step of the CoRe concept. On 29 September it arrived at the site, and the connections, start-up phase and clean-water tests will take about four weeks to complete. The installation will then be fed with WWTP Roermond’s incoming wastewater – the influent – at which point the research will officially commence. The pilot research involves an endurance test lasting one year. Activities during this period will include an examination of the quality of the products, the stability of the technology, and the consumption of energy and chemicals. This information will be needed for the further development of this pioneering treatment technology. In parallel, WBL is consulting with representatives of the agricultural and industrial sectors in Limburg about the application possibilities for the treated water.
Collaboration and funding
The research project is being carried out in collaboration with the Rijn and IJssel Water Authority, the Vallei and Veluwe Water Authority, KWR Water Research Institute, Allied Waters, RoyalHaskoningDHV and BLUE-tec, and is co-funded by the Premium of the Top Sector Alliances for Knowledge and Innovation (TKIs) of the Ministry of Economic Affairs.