Blog 27 March 2026

AquaNL day 2: Water in the circular economy

On Wednesday, 18 March, the KWR programme at Aqua Nederland was dedicated to WiCE: Water in the Circular Economy. The day demonstrated how research into flexibility in drinking water assets, the circular recovery of basic materials and smart membrane technologies is coming together to establish concrete, scalable solutions. Presentations and discussions highlighted a single common thread: alliances that transcend sectoral boundaries are crucial to make technological innovations genuinely possible in social and economic terms. In this blog, our researchers describe their experiences during the second day of AquaNL.

Flexibility in water – Daniël Bakker

I really enjoyed being at the fair on Wednesday, 18 March, when the spotlight was on our WiCE programme. I was there with a mission. I was eager to continue working on establishing a line of research focused on identifying and applying flexibility in the operations of the drinking water utilities. I was also very interested to know what else the drinking water utilities are doing to optimise their energy management. Using solar panels, perhaps, or batteries?

In addition to my presentation, I was also very inspired by talking to others about the subject: experts from not only the drinking water sector but also other sectors and consultants from different companies. I can take new steps forward with the insights and contacts I acquired!

Daniël Bakker spoke alongside Joost Bouten on ‘WiCE – Flexibility in water: electricity demand management in the drinking water sector’

A circular approach to water and basic materials – Kees Roest

There was a strong focus on circularity on the Wednesday. I talked about circular water treatment and the extraction of basic materials in my presentation, and the session was well attended. With a selection of recent and ongoing collaborative projects with numerous partners in the water sector, I described the present status and developments. There are already wonderful practical examples of recovered raw materials that are now being usefully repurposed. There are still plenty of challenges, too, because the legislation at present is mainly designed for linear chains rather than circularity. In the KNAP project, for example, we focus on nitrogen and phosphate from the water chain, which we not only remove but also successfully recover and apply as a fertiliser. The insights from the KNAP project are helping to accelerate the application of these much-needed fertilisers and to close cycles. As KWR, we work as a knowledge partner on safely exploiting the value of, and value in, water. We focus specifically on devising systemic solutions, symbiosis and value chains in the transition to a circular economy. As far as we are concerned, a circular economy is one that handles products, materials and resources efficiently and in a socially responsible way within ecological constraints so that future generations can continue to prosper. The transition to a circular economy is therefore not an end in itself but a way of accessing prosperity in the future.

Kees Roest gave a presentation on ‘Circular wastewater treatment & raw material recovery’

Value from concentrate – Emile Cornelissen

On 18 March 2026, AquaNL in Gorinchem was all about sustainable water technologies. After Kees Roest’s inspiring presentation about future-resilient industrial water use, I went onto the stage to look in greater depth at an area that is inextricably linked: reusing water and basic materials from concentrate streams. As a researcher at the KWR Water Research Institute and a visiting professor at Ghent University, I believe this represents huge opportunities for the circular economy, especially with the large increase in the number of reverse osmosis (RO) plants worldwide.

The context is clear: RO treats various sources effectively but it produces concentrated residual streams that are challenging. Those residual streams are full of valuable components but they are difficult to process due to their complex composition.

Coupled selective separation technologies, such as nanofiltration in combination with electrodialysis or advanced membranes, provide a solution here. By coupling these technologies, we simplify the streams: salts, organic matter and nutrients are separated in targeted ways.

In his presentation, Emile Cornelissen spoke about ‘Concentrate management – discharge and resource recovery’

This allows us to recover high-quality water for reuse, while the residual streams constitute a source of usable raw materials. Examples are nutrients – nitrogen and phosphorus – that are perfect for the greenhouse and agribusiness sectors. They can be used as fertilisers, reducing dependence on artificial fertilisers and contributing to sustainable agriculture.

Another telling example is free fatty acids (FFAs) from food waste. These short-chain acids, which are produced by the anaerobic fermentation of food waste, are perfect for bioplastics such as PHA, biofuels or chemicals. Even acids and bases can be recovered from concentrated streams with bipolar electrodialysis and then be used in the chemical industry.

Bram Hillebrand spoke on the topic of ‘Warming in the drinking water network’

Joep van den Broeke spoke about ‘WiCE: A collective research programme at the intersection of water, energy, raw materials and the environment’