The HypoWave+ research project in Lower Saxony is testing an innovative method of water-saving agriculture by growing vegetables hydroponically using treated wastewater.
HypoWave+ research project: Hydroponic greenhouse in the district of Gifhorn in Lower Saxony Source: Wiebke Pieper
The HypoWave+ research project in Lower Saxony is testing an innovative method of water-saving agriculture by growing vegetables hydroponically using treated wastewater. This sustainable cultivation method could be a promising solution for regional food production in times of climate change and water scarcity.
Conflicts over water resources are increasingly prevalent and are expected to worsen due to climate change and the growing demand on natural water supplies. Agriculture, which consumes large amounts of water, urgently needs efficient solutions. The HypoWave+ research project in Lower Saxony addresses this challenge by implementing a highly water-efficient system for hydroponically growing vegetables with high-quality recycled wastewater. On August 20, 2024, media representatives are invited to witness the large-scale application of this innovative process within a scientifically monitored living lab.
Water saving hydroponics with treated wastewater
In these times of climate change and local water shortages, a farm in the district of Gifhorn in Lower Saxony is breaking new ground by means of a large-scale experiment with the aim of water-conserving vegetable production: In a hydroponic cultivation system, plants are kept in containers without soil. They are fed via a nutrient solution and are watered with specially treated wastewater.
“Hydroponic systems are already efficient in themselves, as they require only small amounts of water,” says HypoWave+ project manager Thomas Dockhorn from the Technical University of Braunschweig. “The HypoWave system’s special feature is to use treated high-quality irrigation water obtained from municipal wastewater, thus completely replacing the use of fresh water. Compared to conventional agricultural irrigation, water resources can therefore be used much more efficiently.”
Optimized nutrient supply through treated water
The innovative HypoWave system not only offers an alternative to irrigation with drinking water and groundwater, but also uses an optimized nutrient supply.
“The plants are directly supplied with important substances such as nitrogen and phosphorus from the treated water. The water quality is particularly high, as it is rich in nutrients and free from pollutants and pathogens,” explains Dockhorn.
This process was developed and scientifically tested from 2016 to 2019 in the HypoWave pilot project at the Wolfsburg-Hattorf wastewater treatment plant. Funded by the German Federal Ministry of Education and Research (BMBF), the project consortium also investigated the transferability of the process to different applications, process chains for water treatment and different plant varieties in the run-up to the experiment. The first large-scale implementation of the hydroponic irrigation system is now taking place in a section of the 1,600 square meter greenhouse at IseBauern GmbH & Co. KG. As a practice partner in the research project, the agricultural business from Wahrenholz in the district of Gifhorn is assuming responsibility for cultivation in the immediate vicinity of a sewage pond belonging to the Gifhorn Water Association. The implementation has been scientifically accompanied since 2021 in the follow-up project HypoWave+.
Collaborative research and market readiness for HypoWave system
“The launch of this so far largest living lab of its kind by the Ise farmers and the cooperation with the Gifhorn municipal water board is an extraordinary opportunity for research,” says project coordinator Martina Winker from ISOE – Institute for Social-Ecological Research. “We can scientifically accompany the development of the HypoWave system with all its scientific, technical and social innovations from the pilot project to market readiness and deal in-depth with questions of quality management, marketing as well as matters concerning the cooperation between the stakeholders involved.” It would now be a great step ahead for science and agriculture alike if the HypoWave system proved to be viable at this location so that best practice recommendations could be developed for other locations. “It will be decisive for the success of this real-world laboratory that the involved stakeholders from the realms of water treatment, crop cultivation, logistics and trade are well networked and that the products can be successfully marketed via regional sales structures.”
In future, the entire greenhouse area of the Ise farmers can be supplied with HypoWave water. The annual yield of tomatoes will eventually be up to 11,000 kilograms. In the first year of harvest, two of the 15 cultivation lines intended for tomatoes will be grown with treated water. The agricultural products thus obtained will be sold via the farm’s direct marketing, farm stores and regional supermarkets run by project partner Edeka-Ankermann. The cultivation method and certified product quality are communicated to customers via a QR code on the tomatoes’ cardboard packaging.
“We see the cultivation experiment as an investment in the future and a measure to adapt to climate change,” says Stefan Pieper from IseBauern GmbH. “With the HypoWave system, we can become independent of seasonal water shortages and protect our harvests from extreme weather conditions. This cultivation method can therefore prove to be a real alternative for agriculture, mostly because it conserves water, reuses nutrients and enables regional vegetable production. With the living lab we would like to pave the way for this.”
Sustainable water reuse for agriculture and wastewater treatment plants
Cultivation with the specially treated HypoWave water (as mentioned below)is also proving to be sustainable for municipal operators of wastewater treatment plants who want to make their sewage ponds available for water reuse.
“The water needed for growing vegetables is taken from the sewage ponds. It is treated to a high quality in a multi-stage process with a micro sieve, an innovative activated carbon biofilter, a sand filter and a UV reactor. The highly purified water thus obtained flows back into the sewage ponds,” explains Thomas Dockhorn.
This additional purification process saves the operators the costly construction of pumping stations and pipes to the nearest wastewater treatment plant, which would otherwise be required in a few years’ time.
“The cultivation method in a greenhouse with treated water in the vicinity of our ponds is uncharted territory for us, but is already proving to be a win-win situation for agriculture and municipal water utilities,” says Christian Lampe, Managing Director of the Gifhorn Water Association. “We are also hoping for impetus for increased use in conventional irrigation.”
