The decentralized urban infrastructure system DEUS 21.
Water is a valuable resource. New technologies are making it easier to
handle drinking water responsibly, purify wastewater effectively and
even recover biogas and fertilizer. Fraunhofer researchers will be
showing how this is done at the Hannover Fair (23 -- 27 April) in the
House of Sustainability.
Clean drinking water and basic sanitation are human rights. Yet
almost 780 million of the world's population still have no access to
drinking water and some 2.6 billion people live without sanitary
facilities. Water, though, is also an important economic factor: Today,
agricultural and manufacturing businesses already use up more than four
fifths of this precious commodity. And the demand for water continues to
rise. The Organization for Economic Cooperation and Development (OECD)
is expecting that by 2050, global water consumption will have risen by
more than half. Some 40 percent of the world's population will then be
living in regions with extreme water shortages -- 2.3 billion people
more than today.
We have, to date, been wasteful in our use of this valuable resource.
In Germany, each and every individual consumes around 120 liters of
water per day -- they drink only three. Another third is flushed down
the toilet. But in some regions of the world, clean water is much too
precious to be wasted transporting excrement. New technologies are
allowing us to significantly reduce drinking water consumption, purify
wastewater effectively and even recover biogas and fertilizer. The
researchers at the Fraunhofer Institute for Interfacial Engineering and
Biotechnology IGB and System and Innovation Research ISI have developed
the solutions as part of the DEUS „Decentral Urban Water Infrastructure
Systems" project.
Treatment of rainwater
Not all water has to be drinking quality -- for watering the garden
or flushing the toilet, for instance. Using rainwater and treated wash
water for personal needs pays off, especially in arid regions.
Fraunhofer researchers have developed a modern water treatment plant for
this very purpose. It produces germ-free, usable water that satisfies
the requirements of the German Drinking Water Regulation (TVO). "The
treated rainwater can be used for showering, washing, flushing the
toilet and watering the garden," explains Dr. Dieter Bryniok from the
IGB in Stuttgart.
Vacuum sewage systems reduce water consumption
Vacuum sewage is a key building block. The concept drastically
reduces water consumption. Vacuum toilets need only about 0.5 to 1 liter
of water per flush. By comparison: Conventional toilets use between
four and eight liters.
What's more, the investment and maintenance costs are lower than
those for conventional sewage systems. Domestic wastewater is
biologically purified in an anaerobic, high-performance membrane plant.
The heart of the system, fully-mixed anaerobic bioreactors, treat the
wastewater without aeration or oxygen and the organic constituents are
converted into biogas, a mixture of methane and carbon dioxide.
The bioreactors are combined with rotation disk filters. The
wastewater is forced through ceramic filter disks. The rotational
movement of the ceramic membranes inhibits the formation of covering
layers. So the filtration capacity is maintained over a prolonged
period. The purified water drains into the filter plant's hollow shaft.
The pores in the membrane range in size from 60 nanometers and 0.2
micrometers. All larger particles are routed into the bioreactors.
Bacteria are also returned to the reactors, which breakdown the organic
waste that has been filtered out. The recovered biogas provides power
and heat.
The entire plant works in the absence of air. The benefit:
there's no bad odor.
Recovery of biogas and fertilizer
Another special feature of the disposal concept: As well as domestic
wastewater, the wastewater purification plant can also process bio
kitchen waste. Kitchens are simply equipped with a waste macerator,
accommodated below the sink. The system is connected to the domestic
wastewater pipes. As more and more organic waste gets into the
wastewater, the biogas yield increases. Bio-waste and wastewater produce
another by-product: fertilizer. Nitrogen and phosphorus are converted
into ammonium and phosphorus salts and can be recovered through the
applied membrane technology.
As Bryniok explains, "The water management concept DEUS 21 benefits
mainly those regions that still have no water infrastructure with sewage
system and central clarification plant, or in which the old
infrastructure can no longer be modified to meet the new challenges
posed by climate change or de-population." "The system is also ideally
suited for export to water-scarce areas, because it can be adapted
specifically to the needs of dry and semi-arid regions."
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