Bioremediation and Plants

pgharr at pgharr at
Mon Nov 27 01:47:00 EST 1995

I am beginning a program of investigations into the area of
bioremediation in tropical regions, particularly in relation
to its use for herbicide removal through degradation via
microbial, earthworm, photolysis or other natural phenomena.
The target materials are:
2,4-D; picloram; hexazinone; glyphosate; fluroxypyr;
trichlorpyr; diuron; and possibly sulfometuron methyl.  All
are efficient herbicides when appropriately used, giving good
control with a fair residual [where appropriate].  The big
issue is how to adequately handle washdown and drum
disposal/drum wash WITHOUT moving into highly technical
containment such as activated charcoal filters, lime pits etc.
Th object is to develop a system which uses organic material
soil, sewerage sludge, peat, chicken manure etc as a media to
break down the compounds through natural or enhanced natural
Temperatures are high air temp at least 30C+, and soil surface
can reach 70C for some period, the surface can be kept moist
and for about 8+months solar radiation is high.
Advice is sought on:
1. Information on specific strains of bacteria etc capable of
operating efficiently at these temperatures and if not special
strains, are there any directions?
2.  Advice on the most suitable media.
3.  Moisture levels in the media.  Can drying out occur and is
that detrimental to efficiency?
4.  Are worms efficient in assisting the process of
degradation of these compounds?  What types?
5.  Does the media ever need replacing?  If so how do you tell
it is the right time to do so and can that material be
disposed to ground without problems? eg used as mulch or as a
potting mix.
6.  The media is to be kept in a tank, so there is no leakage
to the natural ground...any thoughts on the volume required,
if liquid is say, 5000 litres per week, containing diluted
materials from tank and vehicle washdown plus the very
ocassional tank mix remainder.  Average pan evaporation about
50-60mm per month; area can be covered during rainy periods. 
And is large surface area preferable to a deeper pit?
7.  Any comments on "best practice" for such an operation?
There is a lot of qualitative info about but nothing very
definite.  Would appreciate any information or direction to
appropriate literature, experiences etc.  Liquid volumes may
be reduced by reuse of the liquid where possible.
Would also appreciate comments regarding use of a smaller
separate activated charcoal system to "catch" hexazinone,
which has a long half life and toxic to woody trees at low
dosage, so that guns used for the chemical could be washed out
independently, before liquid went to the main unit.
Please email directly or fax to +61-89-481894 or post to PO
Box 40493, Casuarina, NT 0811, Australia.
System could have potential for many areas in tropics if could
be made operable.
Peter Harrison...Agricultural and Environmental Scientist

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