Regional conflicts over the utilisation of water resources are not uncommon and will be exacerbated by climate change and the increasing strain on natural water resources. Water-intensive agriculture in particular is dependent on efficient solutions. In the HypoWave+ research project, a farm in Lower Saxony, Germany, is currently implementing a particularly water-efficient process for the hydroponic cultivation of vegetables using high-quality recycled wastewater. The media were invited to visit the large-scale implementation in this scientifically supported real laboratory on 20 August 2024.
Water-conserving
In times of climate change and local water shortages, a farm in the district of Gifhorn in Lower Saxony is breaking new ground with a large-scale trial for water-conserving vegetable cultivation: in a hydroponic cultivation system, plants in containers without soil are fed via a nutrient solution - with the addition of treated wastewater.
"Hydroponic systems are already efficient in themselves, as they require little water," says HypoWave+ project manager Thomas Dockhorn from the Technical University of Braunschweig. "The special feature of the HypoWave system is that we obtain high-quality treated irrigation water from municipal wastewater, which completely replaces fresh water. Compared to conventional agricultural irrigation, water resources can therefore be used much more efficiently."
More efficient cultivation method for agriculture
The innovative HypoWave system not only offers an alternative to irrigation with drinking water and groundwater, but also an optimised nutrient supply. "The plants are supplied with important substances such as nitrogen and phosphorus directly from the treated water. The water quality is particularly high, as it is rich in nutrients and free from pollutants and pathogenic germs," 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 Federal Ministry of Education and Research (BMBF), the project network also investigated the transferability of the process to different applications, process chains for water treatment and different plant varieties in advance. The first large-scale implementation of the hydroponic irrigation system is now taking place in a section of the 1,600 square metre greenhouse at IseBauern & Co. As a 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. Implementation has been scientifically monitored since 2021 in the follow-up project HypoWave+.
Largest real-world laboratory of its kind
"The commissioning of the largest real-world laboratory of its kind to date 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 maturity and deal intensively with questions of quality management, marketing and cooperation between the stakeholders involved." It is now important for science and agriculture alike that the HypoWave system proves to be viable at this location so that best practice recommendations can be developed for other locations. "It will be crucial for the success of the real-world laboratory that the stakeholders involved from the fields of water treatment, crop production, logistics and trade are well networked and that the products are successfully marketed via regional sales structures."
Despite water scarcity: regional food production in times of climate change
The entire greenhouse area of the Ise farmers can be supplied with HypoWave water in the future. The annual yield of tomatoes will then be up to 11,000 kilograms. Of the total of 15 cultivation lines, two lines are planned for tomato production with treated water in the first harvest year. The products will find their way to the market via the farm's direct marketing, farm shops and regional supermarkets run by project partner Edeka-Ankermann. A QR code on the cardboard packaging of the tomatoes allows customers to track the cultivation process with certified product quality. "We see the cultivation trial as an investment in the future and an adaptation measure to climate change," says Stefan Pieper from IseBauern Ltd. "With the HypoWave system, we can make ourselves independent of seasonal water shortages and protect our harvests from extreme weather conditions. This form of cultivation can therefore be a real alternative for agriculture, not least because it conserves water, reuses nutrients and enables regional vegetable production. We want to pave the way for this with the real laboratory."
Advantages for operators of municipal sewage treatment plants
Cultivation with HypoWave water is also proving to be sustainable for municipal operators of wastewater treatment plants who want to make their sewage ponds available for water reuse. "We take the water from the sewage ponds that we need for growing vegetables. It is treated to a high quality in a multi-stage process with a micro sieve, innovative activated carbon biofilter, sand filter and a UV reactor. The excess water flows back into the clarification ponds in a highly purified state," explains Thomas Dockhorn. This additional purification process saves the operators the costly construction of pumping stations and pipes to the nearest sewage treatment plants, which would otherwise be necessary in a few years' time. "The cultivation method in a greenhouse with treated wastewater in the neighbourhood of our ponds is completely new for us, but is already proving to be a win-win situation for agriculture and municipal water companies," says Christian Lampe, Managing Director of the Gifhorn Water Association. "We are also hoping for impetus for increased utilisation in conventional irrigation."
For more information:
www.hypo wave.de
www.isebauern.de