Can wastewater help combat drought?
With summer droughts increasingly affecting Flanders, the need for innovative and sustainable water management solutions is growing. Two young researchers from Vrije Universiteit Brussel, hydrologist Laura Speijer and analytical chemist Delphine Vandeputte, are taking the lead in a groundbreaking project exploring how treated wastewater can be used to irrigate farmland and replenish groundwater. Their work, which uses the technique of subirrigation, is showing promising results and offers a perspective on a more robust water system for the future.
Dry summers, falling groundwater levels, and increasing water scarcity: it’s a problem Flanders has been struggling with more and more in recent years. This summer, too, drought will once again be strongly felt. Farmers and citizens are concerned, while debates in the Flemish Parliament about drought, water shortages, and the Blue Deal are in full swing. To tackle these challenges, researchers at Vrije Universiteit Brussel (VUB) are joining forces to find smarter ways to use our water. This innovative project on the reuse of treated wastewater makes an important contribution to the fight against drought. The Soil Service of Belgium, Aquafin, and Boerennatuur are also actively involved.
Reusing water in times of drought
The research arose from the urgent need to address drought and water scarcity. “In recent years, Flanders has seen stricter restrictions on water use during dry periods, with significant consequences for agriculture and industry,” explains Laura Speijer, who works as a hydrologist on the project. “That’s why we’re looking at alternatives, such as reusing treated wastewater through a technique called subirrigation. This involves delivering water directly into the soil, which not only irrigates crops but also replenishes groundwater.” Delphine Vandeputte, an analytical chemist, is responsible for researching water and soil quality: “We analyse soil and groundwater samples to determine how safe and effective the use of treated wastewater is. We look at the chemical composition of the water and whether any substances end up in the crops.”
Saving water through subirrigation
The innovative subirrigation technique works via a network of drainage pipes beneath the fields, injecting water directly into the soil. This reduces evaporation losses and immediately replenishes groundwater.
“During the dry summer of 2022, we already saw remarkable results,” says Laura. “Our test fields remained noticeably greener than the surrounding fields, and the groundwater level locally rose by about 30 centimetres.” In addition to technology and water analysis, communication also plays an important role in this project. After all, the idea of reusing water can raise questions among the general public. “People are often put off by the thought of ‘wastewater’, even if it’s been treated and is perfectly safe,” says Delphine.
That’s why communication scientists Pascal Verhoest and Joke Bauwens are also involved in the project. They explore how to clearly explain such innovative solutions and build public support. “We really do speak a different language,” laughs Lara. “But thanks to the input from communication experts, we’re learning how to present our research in a clearer and more accessible way.
A glimpse into the future
"The project is still very much in development, but the initial results are promising. Looking ahead, there’s also potential for applications beyond agriculture—such as using treated wastewater in industrial processes, or even for drinking water production.
“We’re only just beginning to explore what’s possible,” Lara concludes. “But the droughts we’re seeing today show that we need to act now. Innovative solutions like this could play a vital role in managing our water resources in the future.”
