Advice needed about biofilms

DeWayne Townsend d-town at maroon.tc.umn.edu
Mon Feb 16 20:43:33 EST 2004

Dr. Maurice
   I don't think the brown material is a "biofilm" since the time required to
run the water through cotton wool is too short.  I think that what you have
is interference by lignins or other types of bio-polymers.  Try using a
filter, like Millipore, that does not adsorb your marker prior to the cotton
wool.  You could also use a molecular seive that would let you marker pass
through and retard the interfering compounds.  Just a thought.

 > I am a hydrogeologist using an optical brightnener for groundwater
 > tracing. We inject the tracer into a borehole/ soakaway/ sinking
 > stream.  We then use small balls of cotton wool (approx. 5 cm
 > diameter) to detect the optical brightener in springs, boreholes and
 > rivers, to prove groundwater connections.  I have found that in the
 > river we need to sample, the cotton wool becomes coated in a brown
 > slime, presumably a form of biofilm, preventing the absorbtion of the
 > fluorescent tracer.  I have tried covering the cotton wool in netting,
 > cloth, plastic mesh and wire mesh, but the cotton wool still becomes
 > coated in the biofilm.  I know absolutely nothing about biofilms but
 > wonder if there is any method of preventing the cotton wool becoming
 > coated in biofilm, yet still allowing the water to flow through the
 > cotton wool and the optical brightener to be absorbed.  Perhaps there
 > is some treatment I could apply to the cotton wool?  Any advice would
 > be greatly appreciated.
 > Louise Maurice

DeWayne Townsend, Ph.D.

d-town at maroon.tc.umn.edu


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