Agricultural areas
in the Vietnamese city of Da Nang: in the future,
residents can use
purified wastewater to water their crops. © Fraunhofer IGB
(September 3, 2015) To
meet the requirements of Asian cities, researchers are adapting an idea they
have already applied in Germany for comprehensive water management: They are
developing a concept for reducing water use, treating wastewater and extracting
fertilizer for a strip of coastline in the Vietnamese city of Da Nang.
Urbanization is in full swing. Particularly in Asia,
solutions are needed for feeding the growing population, supplying water and
energy, and cleverly recycling waste wherever possible. In Vietnam, researchers
from the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB
in Stuttgart have adapted a wastewater treatment concept they developed in the
DEUS 21 project to support the supply of water, energy and fertilizer.
Under the auspices of the German Society for International
Cooperation GmbH (GIZ), the “Integrated Resource Management in Asian Cities:
The Urban Nexus” project will now implement the innovative infrastructure along
a strip of coastal land with some 200,000 residents in the Vietnamese city of
Da Nang. Starting in the fall, 110 plots – home to around 500 people – are to
be connected to a novel sewage network made up of vacuum pipes, which have a
significantly smaller diameter than standard pipes. Wastewater is extracted
with pumps, similar to the process used in trains and aircraft.
Until now, Da Nang’s wastewater often flowed untreated into
leaky ditches. Not only does this risk contaminating beaches, it also leaves
untapped a valuable resource that the Fraunhofer researchers are now making
accessible. Now for the first time, wastewater will be processed together with
hotel kitchen waste; the resulting biogas will be used for cooking in hotel
kitchens. Treated water will be used for urban agriculture – meaning farmers
will require less groundwater, reserves of which are at risk of becoming ever
more saline as seawater is drawn in to replace the excessive volumes of freshwater
being extracted during periods of drought. A further advantage is that
nutrients found in the processed wastewater work as a natural fertilizer. So
the novel system connects the pressing issues of supplying water, energy and
food with little effort – and the researchers achieve good results in each
area. For example, with biogas: “At 45 liters per resident per day, our
solution produces twice as much biogas as with traditional water treatment
plants in Germany,” says group manager Dr. Marius Mohr from the IGB.