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tenance separation toilet on an industrial scale all failed. The models were prone to
either clogging by foreign bodies or paper, were negatively affected in their flushing
performance, proved to be too maintenance-intensive or led to odour nuisances. Ulti-
mately, their use was always too cumbersome and mostly not designed for the diffe-
rent sitting positions of men, women and children. Through intensive design research,
EOOS has worked out the basics for an ergonomic urine separation toilet. Using a ther-
mal camera, recordings of the urine stream of men and women were researched. The
next step in the further development towards a market-ready separation WC was taken
in collaboration with ETH Zurich, which carried out the corresponding flow calculati-
ons, Eawag and the development team of Swiss bathroom manufacturer Laufen. The
result celebrated its premiere under the name of save! at this year's ISH sanitary trade
fair in Frankfurt and can be seen until 1 September as part of an installation we desi-
gned for the "Broken Nature" exhibition at the Milan Triennale.

Passive waste water separation using the teapot effect

The "technology" behind our WC design is very simple and does without any mecha-
nical parts. Instead, the separation of urine and faeces is achieved solely by the para-
meters of surface tension, water flow and ceramic design. We use the fact that the
quantity and flow velocity of liquids determine their flow behaviour. Anyone who's
ever used a teapot knows: If the quantity of tea is large and fast enough, the liquid is
poured into the cup in a bow. If the quantity and speed of the tea decrease when the Die Form wurde über Computersimulationen ermittelt. • The shape was determined by computer simulations.
teapot is put down, the residual liquid flows down the spout. Thanks to this effect, the
urine (small quantity, flowing slowly) and the following flushing water (abundant, flo-
wing fast) are passively separated from each other in our separation WC. This works
for men, women and children alike, apart from a certain limitation for some male toilet
users: To ensure that the urine is collected optimally, users are asked to pee sitting
down! The urine is then discharged via a separation opening not visible to the user,
the so-called Urine Trap, and discharged via a separate wastewater pipe for further
use, for example to the in-house treatment plant in the basement. A urine siphon, Installationsansicht mit zwei getrennten Fallrohren • Installation view with two separate downpipes
which Laufen specially developed for this purpose, provides an odour seal. The water
from the flushing process, in turn, is fed into the normal drain, together with solids
and foreign substances. In practice, this technique succeeds in separating up to 80 per-
cent of the urine with a low dilution. In order to be able to subsequently use the urine
separately, yellow water piping must be provided in addition to black water piping.
The urine can then be collected in tanks in the basement, where it can be processed
into fertiliser. This infrastructure is particularly useful in urban expansion areas, where
existing sewage treatment plants would have to be expanded at high cost. If no yellow
water arrives at the wastewater treatment plant, it can be scaled down up to ten times.
Decentralised urine treatment is also conceivable, especially if the surrounding area is
an agricultural area. Thus, valuable nutrients are returned to agriculture instead of fer-
tilizing the carpets of algae in coastal areas.

Developing countries benefit from the Urine Trap

Thanks to the perfect integration of the new Urine Trap technology, the save! model
from Laufen hardly differs in appearance from other high-end toilets. At present, the de-
velopment has been registered as an international patent and complies with current Eu-
ropean standards. The all-round enamelled ceramic body is easy to clean and equipped
with a rimless flush. EOOS and Laufen are well aware that the introduction of separate
wastewater management in the developed Western countries alone will hardly suffice
to solve our global environmental problems. Rather, in future it is an issue of establis-
hing comparable systems in the rapidly growing metropolises of developing and emer-
ging countries. Laufen has therefore decided to take an unusual and far-reaching step:
In order to ensure that the Urine Trap technology is spread around the world as far as
possible, the company is currently working with us on the development of a urine-
saving squat toilet for re-production and distribution in emerging and developing coun-
tries. In order to underline the social commitment of Laufen and EOOS, both partners
in the project for the Bill & Melinda Gates Foundation forego license fees from the sales
of the squat toilet in developing countries. The developed industrial countries are also
developing countries in terms of a sustainable development of our sewage system. We Grafik: EOOS; Foto: Laufen
therefore hope to enthuse politicians, investors and architects for the toilet revolution.
The toilet needed for that is now available!

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