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Purifying water -

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Naomi Fowler: There's no mystery to cleaning up polluted water, we've been doing it for a long
time, quite expensively, using UV light. But this system here is quick to build and, because it
uses photons from the Sun, it's cheaper to run.

Dr Jung: We concentrated on low installation and maintenance costs, of course, because we mainly
apply the sun and have much less pump energy, so we save about 90% of the energy. So there, you can
have a look at that.

Naomi Fowler: Dr Jung is proudly showing me his prototype, six panels that just slot together with
rows of clear tubes for the water to run through. It's angled a bit like a sunflower to catch the
best of the Sun's rays, even on this cloudy German afternoon.

Okay, so tell me how it works.

Dr Jung: What's happening here is that we pump the water that is to be cleaned through the tubes,
and the water is before mixed with the catalyst and in this case with some oxidant, and by
sunshine, like now, purification processes are induced. We usually apply iron salts, just soluble
iron, and the other catalyst that is supplied is titanium dioxide. The iron salts dissolved in the
water and the iron salts can be converted in hydroxides after the treatment and they can be
filtered off after then.

Naomi Fowler: So what kind of waste water can you treat here, and how fast can you do it?

Dr Jung: This prototype loop has a capacity of 140 litres, and we checked antibiotics and X-ray
contrast agents and they usually occur in concentrations of about one to five milligrams per litre,
so low concentrations, and this pollution is being removed in ten minutes. So we have here just ten
minutes and then the water is clean.

Naomi Fowler: Wow, really? But isn't it right that there's residues of various drugs that stay in
the water when it's been through a biological process?

Dr Jung: Things like that we can treat with this process, so we are concentrating on industrial
water containing chemicals, toxic chemicals or persistent chemicals that are not affected by
biological treatment. So we checked also degradation of some compounds from the textile finishing
processes, where we have the washout from the nylon finishing, and a typical concentration was
about 130 milligrams per litre [?] and here we are had 100 litres purified to 80% in about 60
minutes. Quite fast, I think.

Naomi Fowler: And what's also pretty fast is actually building the plants.

Dr Jung: The glass tubes are constructed on a frame which can be easily mounted to a supporting
structure, and it's possible to scale up such a plant by mounting enough modules. So now we
installed a demonstration plant with 240 square metres, and the plant with 240 square metres was
erected in two days. It's quite fast, just because it's consisting of modules and stand-outs,
supporting structures, which are normally applied for photovoltaic systems. So a plant can be
erected quite fast, and it's optimised to be cheap and to have a practical technique.

Naomi Fowler: So are there many of these systems in operation commercially?

Dr Jung: Not yet, this was a research project which is ending in January, so we are now in the
final phase of the project, and we have now erected the demonstration plant which went in operation
this week. So the first tests with degradations have been done today. So in principle you can buy
this technique from now on.

Naomi Fowler: So whereabouts would it be useful, this kind of system?

Dr Jung: It's meant for places where you have industrial activity and where you generate polluted
water, so it's anywhere where you have enough sun. So usually we think of the Mediterranean area
and North Africa, also in some areas in the USA also where you have enough sun and where you have
industrial activity.

Naomi Fowler: So, for many countries around the world, help from the Sun's rays to clean up toxins
from their water. And here at this Institute for Technical Thermodynamics they've also proved the
principle of using solar treatments for contaminated air. This is Naomi Fowler in Cologne, Germany,
for The Science Show.


Naomi Fowler



Robyn Williams


David Fisher

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