nocardia bacteria

K N and P J Harris ecoli at cix.compulink.co.uk
Fri Nov 10 09:18:43 EST 1995


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> bionet/mycology #567, from parex1 at vianet.on.ca, 2706 chars, 7 Nov 1995 
15:03:25 
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> Article: 2602 of bionet.mycology
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> From: DON KRESS <parex1 at vianet.on.ca>
> Newsgroups: bionet.mycology
> Subject: nocardia bacteria
> Date: 7 Nov 1995 15:03:25 GMT
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> I am a layperson in this subject so forgive any biological 
inaccuracies 
> please.
> 
> A problem with the local municipal sewage water treatment plant is 
> occurring in my area and an organism they said had been identified as 
> "nocardia filamentous bacteria" is the culprit.  The effect the 
> organism's growth has is to cause a brownish foam several inches thick 
to 
> appear on the surface of the water in the clarifier tanks which is a 
> final stage of the water treatment process.  The surface skimming 
rakes 
> that the tanks are equipped with are not designed to handle this 
> thickness and consistency of foam.  The net result is foam carryover 
into 
> the effluent stream.  This is environmentally unacceptable and they 
are 
> looking at remedial measures such as physically removing the foam 
using 
> vacuum trucks on a temporary basis and improved surface skimming 
> equipment for the long term.
> 
> The problem has been a recurring one over the last ten years and is as 
> bad as it has ever been right now.  The plant operators have not been 
> able to establish a cause and effect relationship to explain this 
> phenomena.  A mechanism that was described is that this bacteria 
attaches 
> itself to oil and\or grease and floats it to the surface.  The plant 
has 
> a high throughput and the sewage has a short residence time.
> 
> My focus is to attempt to identify the root cause of the problem.  
> Presumably this bug is always present and will grow to objectionable 
> levels only under certain conditions.
> 
> Questions:
> 
> Am I in the right newsgroup?
> 
> Has anyone seen this sort of effect in a sewage treatment plant and 
was 
> the root cause identified?
> 
> Are there certain compounds in the sewage water entering the plant 
that 
> would cause this organism to proliferate?
> 
> Could waste water from petroleum refining which may contain 
miscellaneous 
> trace amounts of hydrocarbon compounds create favourable growth 
> conditions for this organism?
> 
> Any tips on other questions jor things I should be considering?
> 
> Any references to other souces of information would be appreciated!
> 
> DEKress
> Ontario
> Canada
> 
Never heard of this one before but then I'm a soil rather water person. 
The Nocardia group are pretty resourceful and traces of hydrocarbons 
could be right up their street. Air stripping might be an idea but the 
cahnces are that these hydrocarbon traces are not the most volatile. It 
would be interesting to check the water pH. Only a guess, but I would 
bet that the pH is in the 7.0 to 8.0 region when these become a pest. A 
little judicious acidification might do the trick.
Peter Harris,
Reading University, UK.
AKA P.J.Harris at reading.ac.uk

Opinions are none but mine own.




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