Re: Radioactivity in municipal sewage

[Franz Schoenhofer <schoenho@via.at>]

At 16:21 01.08.2000 -0500, you wrote:
>August 1, 2000
>Davis, CA
>
>Waste water treatment plants at major cities will find I-131 coming through
>because medical treatments involve excretion. Although the half-life is
>short, it seems to me this may be a problem that needs to be addressed.
>

We have done quite a bit of work on the "problem" of waste water treatment
plants and the sewage sludge already in the early eighties and I remember a
conference organized by the IAEA in 1980 (or 1981) in Berlin, where Swiss
papers were presented on the measurement of I-131 in waste treatment plants
and sewage water. 

We were very happy to "see" some radionuclides on our high resolution
gamma-spectrometric equipment, since before we had measured only
environmental media which showed no artificial radionuclides except air
particulate filters after the Chinese test of 1980, where we were very
proud to detect some fission products. In the water leaving the Viennese
main sewage treatment plant we could find all the radionuclides used within
the last few days in Viennese hospitals - iodine-isotopes, Tc-99m (I even
designed a very quick ion-exchange method to extract it very fast from the
water), Ga, Tl,...... Many of them could still be detected in the sewage
sludge, but since in nuclear medicine only short lived radionuclides are
used most of them had decayed already and when this sewage sludge was
centrifuged and burnt there was practically nothing to be detected any
more. At many occasions we even found I-131 in surface water like the
Danube river in spite of the huge dilution by the rivers and the relatively
short halflife. 

After the Chernobyl accident with concentrations of fission products in
surface water, food and the environment being several orders of magnitude
higher at least  m y  interest in such measurements has declined to zero. 

The concentrations we found, were a confirmation, how sensitive our
instruments were and how skilled we were to find easily these
concentrations, but from the radiation protection point of view, there is
nothing to be worried about and nothing to be addressed. First of all the
waste water from the treatment plants is not consumed, so it cannot enter
the body directly. Assuming that drinking water would be produced by "river
bank filtration" (sorry, it is a word by word translation of a German
technical term), the filtration takes a long time and even I-131 would have
decayed, not to talk that the radionuclides would be adsorbed by the soil
which the water has to pass through this filtration. The doses
theoretically caused by these radionuclides - even if you would drink the
waste water! - are totally negligible.

There are many data available on such measurements, but as far as I
remember we had them published only in German in our reports. Anybody
interested more in this topic is welcome to contact me preferentially at my
private e-mail address.

Regards,

Franz


Franz Schoenhofer
Habicherg. 31/7
A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at


Please note my new telephone number at my office!

Office:
Ministerialrat Dr. Franz Schoenhofer
Federal Ministry of Agriculture, Forestry, Environment and Water Management
Radiation Protection Department (BMLFUW I/8 U)
Radetzkystr. 2
A-1031 Vienna
AUSTRIA

phone: -43-1-71100-4458
fax: -43-1-7122331

************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html