Research & Technology
facts & figures

At the pilot facility in Hattorf, a nutrient solution feeds butterhead lettuce that is planted in soilless containers


Huge amounts of freshwater are needed for agriculture worldwide. A team of researchers wants to change that by growing vegetables in treated wastewater

After numerous tests,it was determined that butterhead lettuce was the vegetable that was best suited for trials of a potentially revolutionary technique: hydroponic gardening with treated wastewater.

In hydroponics, plants grow not in soil but in containers, where they are supplied with nutrients. Vertical farming projects such as AeroFarms in Newark (USA) use freshwater for this purpose. The research project HypoWave is taking a different approach. “Wastewater contains many nutrients as a matter of course. Our technique could make these nutrients usable for food production and at the same time significantly reduce the huge amount of water that is consumed in agriculture,” says the project’s manager, Thomas Dockhorn from the Institute of Sanitary and Environmental Engineering at the Technical University of Braunschweig.

However, many questions still need to be clarified before then. As a result, the research team has created a pilot facility at a sewage treatment plant in Hattorf near Wolfsburg. “Here, we want to find out how we can optimally adapt wastewater treatment to the plants’ nutrient needs,” says Dockhorn. The researchers are also investigating the technique’s profitability and marketability.

A total of twelve partners are involved in the HypoWave project, which is being coordinated by the independent Institute for Social-Ecological Research (ISOE) in Frankfurt am Main.


Torsten C. Schmidt

»We’ve Obviously Struck a Chord«


The University of Duisburg-Essen has been offering a degree program in water since 2001. What exactly does it involve?

We combine chemistry, microbiology, and process engineering. It’s without parallel in Germany. At the end of the program, graduates can help to optimally use and protect water as a precious resource.


Has the program met with a good response?

We’ve had about 60 to 100 students begin this bachelor degree program every year since it was launched. We’ve obviously struck a chord with our interdisciplinary approach and the program’s strong environmental component.


How can the graduates help to improve the water supply?

They can do this by inspecting the hygienic and chemical quality of drinking water in developing countries, for example, and by making sure it meets the requisite standards. Such expertise is also important in western Europe, because we can’t be sure that climate change will leave us with sufficient amounts of clean drinking water in the future.

Torsten C. Schmidt

is a professor at the University of Duisburg-Essen and Director of the Center for Water and Environmental Research.


percent of the freshwater consumed worldwide is needed for agriculture. Industry consumes 19 percent and 12 percent is used by communities and private households

These Vietnamese farmers use the SoDis method to purify their drinking water themselves


A simple water purification method could save millions of lives. However, there are problems in its use and acceptance

Two actors in a street theater performance bend forward to suggest a stomach ache, while a bacterium dances behind them to show that it is the cause of their suffering. The sun then suddenly appears, carrying a PET bottle full of water in its arms. The bacteria twists and turns as it dies. The two actors drink from the PET bottle and immediately feel better.

This performance in Bolivia advertises the solar disinfection (SoDis) method, which uses UV radiation and heat to purify drinking water. SoDis kills off harmful microbes in contaminated water. It was developed by the Swiss research facility Eawag, which has been struggling to introduce the method worldwide since 1999. It works as follows: Contaminated water is filled into a one or two-liter PET bottle which is left to lie up to six hours in the sun. After this period, the water is drinkable, without requiring any boiling or chemicals.

According to the World Health Organization (WHO), SoDis can save the lives of millions of people who die every year from diarrhea. Not only is the method simple, it costs almost nothing to carry it out. SoDis works perfectly in the lab, where it thoroughly purifies water. However, it is often improperly implemented in practice, despite the efforts of many aid organizations.

“It takes a lot of time to change people’s habits and their daily routines,” says Valérie Cavin, a water expert at the Swiss development aid organization Helvetas, who has been working on the SoDis project for the last five years. “They often forget to put the freshly filled bottles out into the sun in the morning or they drink the water before it has been completely disinfected.” That’s because the water needs to be outside for two whole days when the sky is overcast. Another problem is that some people don’t think the method is effective. It seems too easy to them, even though simple solutions are sometimes the best.

An Inexhaustible Source of Energy

Water has been an important supplier of energy According to the BP Statistical Review of World Energy, hydroelectric power covered 6.9 percent of global primary energy needs in 2016. China is the world’s leading consumer of such energy. Last year the country consumed 1,162 terawatt- hours of hydroelectricity. Germany ranked 24th, at 21 terawatt-hours.

Top 10: consumption of hydroelectricity in 2016

Amounts in terawatt-hours