Chances for Concentrate

In this project, we are investigating how the circular processing of concentrated residual streams can contribute to future-resilient and socially responsible freshwater supplies. This involves recovering water and producing raw materials for which there is a market. The project is part of the Water in the Circular Economy (WiCE) programme of the Sector Research (BTO) of the water companies.

Exploiting concentrated residual streams

Regulatory agencies are imposing increasingly stringent guidelines for the quality of drinking and surface water. At the same time, the current freshwater supplies are under pressure. There are three causes:

  1. the increasing salinisation of groundwater and surface water systems;
  2. emerging substances in sources;
  3. rising water demand due to factors including population growth, data-centre construction  and climate change.

Solutions to these challenges can be provided by incorporating robust(er), resilient and efficient treatment technologies in the current freshwater system. But also by the cross-sectoral (re)use of freshwater and its components, and thermal/chemical energy, which is in line with sustainability objectives. Making alternative water sources available and extractable in a location-independent manner could also be a solution.

The issues sketched here require increasingly sophisticated treatment techniques such as membrane technology. This technique produces, in addition to very pure water, a residual stream with substance concentrations that are higher than in the source. In this project, we are investigating the technical feasibility of sustainable and circular approaches to processing waste streams, taking existing and possible new obstacles to the processing of these streams into account. In collaboration with the project partners, we are elaborating a practical and acceptable perspective for the future in a broad context.

Lab-scale exploration of the potential for alternative approaches to treating residual streams

The project is investigating at the lab scale the extent to which brackish groundwater (concentrate) can be treated to produce high-quality fresh water in addition to salts that can be used by industry. This fresh water could be used for the production of drinking water and, for example, to water plants, as cooling water or even for irrigation. In addition, we are also conducting a lab-scale investigation of the potential of supercritical gasification for residual streams containing organic material.

The concentrated organic residue streams to be tested come from various sectors (drinking water, waste water, industrial and agricultural sectors) and we are focusing specifically on the potential of combined gasification. In this process, organic components are converted to high-calorific gas, producing demineralised water and a solid residual stream of inorganic components. Particular attention is being paid to the possible breakdown of organic micropollutants that may take place during this process. These are substances such as pesticides and medication metabolites that are potentially broken down during the conversion to high-calorific gas.

By comparing the social values of these innovative techniques with the current approach to residual stream management, it is possible to consult with relevant parties such as legislative and regulatory bodies about the preferred route to minimise, where possible, the impact of processing these streams.

Knowledge sharing and dissemination

The results of the activities described here will be shared and discussed with the participating parties at three workshops. During the first workshop, on the basis of the experience acquired during the lab studies, relevant technical aspects in the given conditions, such as further optimisation and/or scaling up where possible, will be considered with the project partners. The second workshop will address the question of how the development of sustainable (or more sustainable) residual-stream treatment techniques for the entire water sector affects socially inclusive entrepreneurship. The third workshop will look at the policy aspects of the large-scale (or larger-scale) application of sustainable residual-stream treatment techniques.

In conjunction with these workshops, there will be a co-creation session as a final dissemination activity. In addition to the project partners, other relevant parties will be invited to attend, such as legislative and regulatory bodies, municipal civil servants, and bodies with system responsibility such as Rijkswaterstaat. We are working jointly towards a practical and socially acceptable future perspective for the treatment of residual streams containing organic material and brackish groundwater concentrate flows.

Artist impression: the circulaire watersystem in 2050.