Making optimum use of each drop of water

Last summer, we saw once again how vulnerable the Netherlands is to drought. The lack of rain had a particularly big impact on nature, agriculture and drinking water supplies. For centuries, the focus in the Netherlands has been on keeping water out and discharging it, but now it turns out we need that water more than ever.

The quality of the water is another cause for concern, due to such problems as salination, medicine residues and industrial materials like PFAS. Quantity and quality are always interlinked, explains Nora Sutton, associate professor of Environmental Technology at Wageningen University & Research (WUR) and affiliated with the Wageningen Institute for Environment and Climate Research (WIMEK). “When water becomes contaminated, the amount that is usable and available decreases. So you can’t treat this as two separate issues.”

Climate-proof water system

To use an integrated approach to tackle these challenges, WUR has joined forces with other science institutes, businesses and partners in the water industry to set up the AquaConnect programme. The programme started in September 2021 and is led by professor Huub Rijnaarts. It aims to design and implement a water system for the future that is climate-proof.

Sutton: “A system like that requires a broad range of options and solutions. You don’t just need the hardcore technological measures but also a sound design for a circular system and a network of producers and consumers. In addition, you need to consider policy, legislation and regulations, and public support for your solutions. All these aspects come together in AquaConnect. That is what makes this approach so innovative.”

Five work packages for research

The various aspects have been divided into five research topics, known as work packages: techniques for modelling groundwater flows; risk assessment for circular water consumption; techniques for purifying wastewater; governance for freshwater supplies; and finally, designs for a smart water network.

Sutton is the project manager for the package dealing with contamination risks. “In this project, we look at the behaviour of impurities with the aim of being able to predict water quality in circular systems. An example is the reuse of purified wastewater – effluent – from sewage treatment plants. We know effluent still contains impurities but we don’t know exactly what the risks are for humans and the environment.”

They are also studying transformation processes. Sutton: “Some substances change composition under the influence of sunlight or bacteria, becoming more harmful as a result. All these insights serve as input for new guidelines, which are needed to determine where it is safe to use purified water.”

Collaboration between scientists and the water sector

The collaboration in AquaConnect between science institutes and players in the water sector is vitally important, says Sutton. “We can make real progress on problems that arise in practice because we have brought in the end users. We can make use of sites such as a groundwater extraction location operated by Vitens, and systems for monitoring and analysis.”

The water partners also provide input for the research. Sutton: “Water boards and drinking water companies know exactly what the challenges are and what restrictions they face. This forms the basis for the design we work on as researchers. In our research, we aim to consider a broader range of options than the water sector would, for example looking beyond current legislation and regulations.”

The research is carried out in four demonstration areas, each with its own set of challenges. Sutton: “The eastern Netherlands has a lot of higher-lying sandy soil where the water flows away easily. So in this area, we’re looking at ways of retaining the water more effectively. In Zeeland, where the big problem is the limited availability of freshwater, we are exploring the options for storing and reusing rainwater and wastewater.”

In the province of Zuid-Holland, researchers are looking at smart ways to bring in major consumers of water, such as industry and greenhouse horticulture, so that the one can use the purified wastewater of the other. Research is also being carried out in an urban setting. Sutton: “In the Marineterrein district in Amsterdam, a pilot has been started for the purification and reuse of urban wastewater for the irrigation of city parks. They need a lot of water in the summer.”

Better and more efficient purification

Sutton is also involved in research into technological solutions. “This involves purification techniques such as membrane technology and electrodialysis. Membranes can be used to remove chemical and biological impurities, while electrodialysis is suitable for inorganic substances such as salt.”

These techniques are already used by various drinking water companies, but there is plenty of room for improvement according to Sutton. “Improvement include purification efficiency and energy consumption. We also look at what kinds of applications and locations specific technologies are best suited.”

Smart water grid

Improved purification also offers opportunities for the development and construction of a smart water grid. This is a network in which users are linked to one another in a way that lets them ‘exchange’ water. Sutton: “An example might be farmers who use purified wastewater from a local industrial park for their irrigation.”

This turns a water consumer into a water producer as well. According to Sutton, the exchange of water does however require close matching of supply and demand. “To achieve this, you need to develop smart digital tools that perform simulations and optimisations. That is why we also use the term ‘digital water grid’.”

Implementation of these technological solutions requires more from the water sector than simply a few adaptations, emphasises Sutton. “A different mindset is needed, one that focuses on circularity rather than linear consumption. That applies not only to users but also to policymakers. Our entire way of thinking about water needs an overhaul.”

It is important that changes such as the reuse of purified wastewater and the use of rainwater are accepted by the general public, says Sutton. “This social aspect is covered in the governance work package. It also looks at the rules and guidelines designed to ensure safety. This is regulated at the national level and the European level.”

Changing laws and regulations

The current laws and regulations provide protection, but they can also be an obstacle at times. That is the case for the reuse of effluent. Sutton: “As of last year, European rules allow the use of this water for certain purposes, but the Dutch law still needs to be amended to reflect this.”

Consideration also needs to be given to how water companies can deal with the residual waste streams that arise from producing clean water, says Sutton. “In some countries, the waste is simply dumped in the sea. But this can cause serious damage to the environment due to high concentrations of certain substances. That is why the Netherlands has strict rules about that. But you still need to come up with a solution that allows companies to get rid of their waste streams.”

Eventually, Sutton hopes her research will have a global impact, one that extends to California for example, the region where she grew up. “Even as a kid, I saw what effect drought could have. We regularly faced water scarcity, so we always had to be very careful at home about using water. That is what drove me to work in this field. I’d love to be able to take the solutions I’m working on in the Netherlands and apply them in California one day.”