Re: Composting WWTPs and composting (Was Re: [compost_tea] Re: MICROBIOLOGY TESTING of COMPOST TEAS

From: L Blair <rlbct_at_clear.net.nz>
Date: Tue, 28 Dec 2004 08:45:11 +1300
Well I'm already happy with the use of properly composted human excreta,
provided it contains no toxins.  And because I don't know much about sludge
production ( I assume loss of some nutrients) I would not go that route
without careful considerations.

But I have a few reservations about using city sewage as an input to the
process.  Maybe just because I don't know enough.  In addition to heavy
metals ( and how much does compost dilute it? obviously you know the mixing
rate.  If its toxic as it is and you dilute it 10:1 or 100:1, that just
shows that there is a limit to how much you can use over time.  And just
because someone establishes a limit doesn't mean that its totally safe below
that limit. anyway, I'm not trying to argue the point here, just explaining
my position. ) there are medical wastes (in particular antibiotics, mood
modifiers, hormones from HRT and birth control, blah blah ...), powerful
cleansers and probably much more.

another aspect of heavy metals in compost ( and I'm sure that you would know
this) is that they become chelated.  I assume by this that this makes the
effects safer.  However, when the humus they are locked up in is used up,
they then come available again.  That's a scary thought.

Lynton

----- Original Message -----
From: "Ted Peterson" <ted.peterson_at_tcsn.net>
To: <compost_tea_at_yahoogroups.com>
Sent: Tuesday, December 28, 2004 7:45 AM
Subject: Re: Composting WWTPs and composting (Was Re: [compost_tea] Re:
MICROBIOLOGY TESTING of COMPOST TEAS


----- Original Message -----
  From: L Blair
  To: compost_tea_at_yahoogroups.com
  Sent: Sunday, December 26, 2004 1:47 PM
  Subject: Re: Composting WWTPs and composting (Was Re: [compost_tea] Re:
MICROBIOLOGY TESTING of COMPOST TEAS


  If sewage sludge was good for farming, farmers would be queuing up,
  demanding it.
  But as a toxic waste, it has to be "sold" to the gullible.

  Lynton


Lynton:

Please get some education on the subject before you write.  Sludge was used
by farmers for years and in much of the world still is used.  In Europe,
biosolids are a mainstay of agriculture.  Traditionally, most of the
problems with biosolids/sludge was in controlling pathogens.  Pathogens can
be controlled quite successfully with current technology and as shaky as EPA
standards seem to be, we have had very few e coli outbreaks due to
spoorization or the use of biosolids.  By the way, there are commercial
products on the market that contain a percentage of human waste.  If you buy
soil amendments, look to see how much or if they contain human waste
products.

Since industrialization of waste treatement and the increase of population
density, the greater problem with human waste products is heavy metals.  The
problem with heavy metals is that they don't necessarily break down in soil
and if the soil pH is off, can be absorbed by certain plants.  As someone
once said: "Sludge is perfectly safe.  I just wouldn't grow my carrots in
it."

Composted biosolids are a completely different thing because green waste is
used to dilute the heavy metals so that the concentrations remain below the
minimum acceptable risk point after several repeated applications.  However,
accidents do happen and people make mistakes.  Such a thing happened in
Germany where people became poisoned by over-application of uncomposted
sludge on food crops.  But the magical thing is that people learned and
there hasn't been a subsequent problem since then.

Now, where would I recommend using composted sludge? Sod farms, lawns,
ornamental plants, grasses, orchards, vinyards and a whole group of food
plants where the food is not grown in the material.  There are people who
think that the only proper disposal of sludge is the land fill. They may
have a point if we don't get a handle on people using sewers as
dispose-alls.  If we can get people to be conscious about what goes into a
sewer pipe, we could process an extremely high grade of soil amendment that
would be safe on all accounts.

By the way, I have completed one project and am involved with others that
compost sludge.  People have already contacted the WWTPs where this is
happening and said they will take every drop made.  So, at least where I am
working, farmers are lining up for the stuff.  No selling.

Ted
SOE





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Received on Mon Dec 27 2004 - 16:37:00 EST

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