More clean water for agriculture and horticulture in times of drought

October 7, 2022

Is it possible to safely use treated wastewater (effluent) from sewage treatment plants (WWTPs) as irrigation water in agriculture and horticulture? A group of water boards, knowledge institutions and companies, led by Wageningen University & Research, have launched a study to investigate how this can work in practice.

Last summer it became painfully clear once again that drought and water shortages for agriculture and horticulture can lead to major damage to crops. Especially in Zeeland and Brabant, the urgency of this problem has been strongly felt in recent years. A number of local and national parties led by Wageningen University & Research have joined forces and are jointly searching for alternative sources of water for irrigation. One obvious source is treated wastewater, effluent, from sewage treatment. However, this water is not clean enough because of micropollutants present, a collective name for drug residues, plant protection products and other persistent chemicals. Within the EffluentFit4Food project, a way is now being developed to analyze the water quickly and inexpensively and, if necessary, post-treat and purify it in a way that is safe, affordable, sustainable and scalable.

Additional purification and testing on growing crop

For this research, a pilot installation with purification equipment has been placed at the Scheldestromen Water Board's sewage treatment plant in Ritthem that now shows a working system as the water could be purified. In the coming months, further testing will be done on this to see if everything is working properly. The technology used, MicroForce++, is based on a combination of degradation by ozone (Oxidation Process) and natural processes. The pilot installation was installed by PureBlue, a company from Kapellebrug that develops innovative systems to purify water.

In another part of the project, this post-cleaned wastewater will be used as irrigation water to grow various crops such as potatoes, onions and pears, and these crops will be examined after harvest for the presence of micropollutants and food safety. The results will be announced later this year. This research should show whether post-cleaning, for example with the system installed at the sewage treatment plant in Ritthem, is appropriate for the contaminants found in the crops.

Legislation and regulations from the EU

The European union recently published a directive: minimum requirements for water reuse. It is now up to national governments to implement these guidelines in laws and regulations. So it will be permitted to use the effluent, provided that those minimum requirements are met. However, not all safety aspects have yet been properly investigated and guaranteed. Project leader Wilfred Appelman: "Particularly in the area of micropollutants, I have concerns about their impact on food safety. So far, this has actually not been sufficiently researched in the Dutch situation. In Israel this has been studied and sometimes a factor 1000 concentration increase of these substances in food has been found."

Project partners EffluentFit4Food

The following knowledge institutions, water boards, agricultural interest groups, technology suppliers and governments are contributing to this research:

Wageningen Food & Biobased Research, Wageningen Plant Research, HZ University of Applied Sciences, HAN Hogeschool van Arnhem en Nijmegen, waterschap Scheldestromen, Waterschap Brabantse Delta, Nederlandse Fruittelers Organisatie NFO, PureBlue B.V., microLAN B.V., Pharem Biotech AB, Provincie Zeeland, Provincie Noord-Brabant en de Topsectoren Agri & Food, Tuinbouw & Uitgangsmaterialen en Water & Maritiem.