Date:         Mon, 22 Mar 1999 12:48:52 -0800
Reply-To:     Alistair Bell <albell@UVIC.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@UVIC.CA>
Subject:      biodegradation, organics, etc.
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Lets think about this subject a bit more...

Where does the rubber/oil/fuel/coolant go? -  on the road and medians, and
into the ditches.  And yes, some of it (who knows how much, I wish those
who are so certain would reference their assertions) is degraded by
bacteria.

And bacteria are capable of breaking down a remarkably wide range of
compounds.

But let me give you one example where the process doesn't quite work as
well as one might hope, that is in the degradation of de-icing fluids used
on airplanes during the winter.

Alot of it (glycols), is used, and it runs off the plane and onto the
tarmac, through the drainage system and into the surface water system
(unless the airport has been constructed recently or has been retrofitted
with a catchment system). These glycols are somewhat toxic, organic or not,
and do affect aquatic organisms in an adverse way.

Unfortunately, what ever bacterial communities (it is often the case that
it is not one particular species that is responsable for bio-degredation,
but a consortium of species/genera) that have adapted to use the glycol as
a carbon source are not too frisky at temperatures that de-icing fluid is
used, so the stuff just drains away into the streams/rivers/lakes in a
diluted form.

The airports that have catchment systems store the de-icing fluid in large
tanks until summertime when they can either feed the stuff into large
bioreactors that have been inoculated with the approriate bacteria and
other nutrients (nitrogen source for example) or onto prepared soil. Some
places have a very short "growing season" and some effort is expended to
make the process as effecient as possible.


Other airports collect the fluids for disposal in incinerators.


When it comes to bioremediation, theory and practice are often miles apart.


Just waking up and mumbling something about organics then rolling over to
go back to sleep is, in my opinion, one of the best examples of hubris.


Alistair