The transition to the way we’ll be handling our wastewater in the future is being shaped by several developments that aim at improving effluent quality, cutting greenhouse gas emissions, recovering valuable resources and energy, and meeting the need for a modular and adaptive treatment concept.
The challenge in this project is to work simultaneously both on improving the sustainability and cost-effectiveness of the treatment process, and on achieving better effluent quality (removal of micropollutants, nitrogen and phosphorus). This involves using the innovative CoRe Water (Concentration, Recovery & Reuse) treatment process, in which the wastewater is first concentrated before undergoing further treatment. This allows sewage water to be treated with more efficiency (including energy-efficiency), with a higher removal efficiency (N, P and micropollutants), and an optimal recovery of resources like nutrients, energy and, most of all, water – from a WWTP to a sustainable water factory.
The preconcentration of wastewater is accomplished using a new technology based on the principle of Forward Osmosis (FO). This is the key step in the production of clean water without nutrients (pathogenic) microorganisms and organic micropollutants (OMP) in a concentrated wastewater stream, which can then be treated with greater energy-efficiency, and from which resources can more easily be recovered. FO is already being applied to a limited extent to industrial wastewater, but has yet to be used for sewage water.
In this project we are working, using FO as the enabling technology, in three subprojects, supported by pilot and parallel laboratory research. This involves studying the extraction of water, energy and resources at different scales. First and foremost, the FO technology itself is the target of research, alongside anaerobic treatment, nutrient extraction and micropollutant removal. The possible applications for the resources are also part of the research.
From laboratory and pilot research using FO technology, it was found that membrane fouling and salt leakage pose the most prominent challenges. Successful control measures have been taken aimed at membrane fouling. At the conclusion of the project we will have sufficient information about the technical and economic potential of the CoRe Water concept, to be able to assess whether it is a full-fledged new alternative for the treatment of sewage wastewater, and whether we know enough about both the overall energy balance and the economic feasibility of the concept. We will also have gained insight into the opportunities for the reuse of water, energy and resources (applications) extracted from the FO’s concentrate.
Pilot projects were conducted at two locations using a Blue-tec pilot installation. Research began on the Wehl wastewater treatment plant (operated by the Rijn en IJssel water authority) where WWTP influent was treated after pre-treatment in a drum screen using the CoRe Water concept. The project generated important information that was used as a starting point for the design of a new pilot project with a larger capacity (up to 2 m3/hour). The pilot project was then set up at a location of the Vallei en Veluwe water authority near a pumping station. The focus here was on the local application of the concept in the future in a residential area. This pilot project tested the effectiveness of air/water flushing (in combination with an osmotic backwash) for cleaning the spiral-wound FO membranes since studies of two bench-scale systems at KWR – which were conducted with the aim of determining the optimal cleaning approach – identified this as a good option for the large pilot project. Construction work on the large pilot project also began in late 2019. Completion is scheduled for April 2020, after which the pilot approach will be tested for a year at WBL’s WWTP location in Roermond.