“In 10 or 20 years, Europe could
well be following the example currently
being set by developing countries.”
Peter Cornel, IWAR Institute at TU Darmstadt
What can be done about this?
Cornel:
These developments demand solutions that go beyond
the structures that exist in the Western world. Whereas we
generally use water only once and then dispose of it as waste-
water, megacities cannot allow water to be used in this way.
They cannot transport water over long distances, process it in
high-quality treatment plants and then use it only once. Cen­
trally organised concepts consisting of a large wastewater treat-
ment plant that feeds sewers are outdated as they have cannot
keep pace with the growth of cities in Asia and don’t meet
current requirements with respect to resource conservation.
How can the new challenges posed by megacities for water
supply and wastewater disposal be dealt with?
Cornel:
In China’s megacities, for example, new housing devel-
opments are frequently built for tens of thousands of residents
by one investor. It therefore makes sense if the facilities for
water supply and wastewater disposal are built at the same time.
The slightly contaminated water from showers, wash basins
and washing machines – referred to as greywater – can be re­
cycled and then made available as reclaimed water for flushing
toilets. This can equate to drinking water savings of between
30 and 40 per cent. The quality of reclaimed water is perfectly
adequate for use in toilets. It can be recycled with minimal
effort, which renders it colourless, odourless and hygienic.
Highly contaminated wastewater from toilets or kitchens can
be recycled for watering green spaces in inner city areas.
The same water can therefore be used not just once, but as
many as three times.
A big advantage of these semi-centralised plants is that
they have the flexibility to grow with cities. They offer much
greater scope when it comes to future planning for megacities
than large centralised supply and disposal solutions. Semi-
centralised plants are ideal for urban districts with 50,000 to
70,000 inhabitants.
Do such semi-centralised plants for water treatment
and consumption already exist?
Cornel:
In Qingdao, the IWAR Institute is currently building a
model plant for 12,000 people in collaboration with our partner
university in Tongji as well as the city of Qingdao and the
organisers of the 2014 World Horticultural Exposition, with the
support of the German and Chinese research ministries. In
addition to water supply and wastewater recycling, the plant
also processes organic kitchen waste, for example. The energy
recovered allows the wastewater treatment plant to operate
self-sufficiently. In addition to water treatment, we are therefore
also making an important contribution in the area of waste
management.
At this point it is clear that the environmental solutions of
the future will incorporate multiple disciplines. Along with
astewater and waste treatment, heat and energy management
also has an important role to play. Wastewater treatment
requires energy, which can be recovered from waste. Another
major contributing factor to the success of semi-centralised
solutions is the increasing degree of automation in areas such
as remote monitoring, where online measurement technology
simplifies and accelerates control and monitoring processes.
Added to this are efficient process automation solutions, which
reduce the amount of energy that the plants consume and
increase their reliability.
Are these developments also the way forward for the current
leading high-tech nations?
Cornel:
The development currently taking place in megacities
is based on technological advances and experience in Europe and
the United States. Germany is one of the technological leaders
in this sector. However, as climate change will require a rethink
with regard to the way in which we use water, Europe could well,
in 10 or 20 years, be following the example currently being set by
developing countries.
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