[USCC] Oxygen in compost, does it really matter

[Cary Oshins]

John and the list,

I did NOT ask if working WITHOUT oxygen matters. Of course it matters a
great deal to those managing and/or paying for the process!  However,
oxygenation, or aerobicity, in composting is not an all or none situation.
There is a continuum from completely anaerobic at <1% O2 to fully aerobic at
>17% O2.  At 5% O2 there will be a fair amount on anaerobic activity, and
there will still be some at 12%.  Odors are closely related to anaerobic
activity, and time-to-maturity is certainly impacted.  Cost of aeration is
undoubtedly the only reason any composter settles for less than fully
aerobic.  The watershed, airshed, wasteshed and neighborshed of each
composter is unique and so each much try to optimize the various factors.  

I am asking an end-product question. Is a compost made at less-than ideal
aerobic conditions (note, NOT ANaerobically, but say 3-5% O2 during the peak
demand of the first few weeks, 5-10% during the next several weeks to
months, and rising to near 21% when matured, screened and ready to use)
significantly different than compost made under ideal conditions, and if so,
in what ways.  How do those differences, if any, affect the end use?  

I hope others chime in.

Cary 

BTW, I don’t think you mean "illusion", below, but probably "impression" :)


-----Original Message-----
From: compost-bounces at composter.com [mailto:compost-bounces at composter.com]
On Behalf Of John A. Crockett
Sent: Monday, February 05, 2007 12:43 PM
To: U.S. Composting Council listserve
Subject: [USCC] Oxygen in compost, does it really matter

To answer Cary Oshins' question, 

Could you work without oxygen?  Maybe that sounds like a stupid question,
but maybe we ought to think like microbes... ask what we need, to be able to
get the composting process done.

Are we striving for excellence in composting?  Are we committed to being a
great neighbor, and environmentally friendly?  Leachate can STINK.  Maybe it
has a lot of microbes in it, wanting more oxygen than is available, and then
those microbes raise a big stink.  If we're going to develop composting and
earn public support for composting, foul odors and phyto-toxins must be
avoided, whatever it takes.

I have the illusion that how fast the biological transformation process gets
done is a matter of microbe-hours per unit of feedstock, appreciating that
just as there are masons, framers, finishing carpenters, roofers, plumbers,
electricians, painters, and more needed to build a house, there are many
different types and species of microbes involved in completing the
composting process.  And most of them won't work without oxygen, some of
them will raise a big stink if deprived of oxygen.   If you and your
neighbors don't mind foul odors, and turn around time doesn't matter, it's
okay if it takes two years, and land costs are nil, maybe it doesn't matter.


I recently learned about an interesting website:  www.compostalert.com.
Apparently someone is not happy with some composting going on near them.
How much is fact and how much is personalities clashing may be debatable.

I also heard about a facility that had been permitted to take in
pre-consumer vegetative food wastes, where the state reportedly revoked
their permit and fined them $3 million.  They had been using passively
aerated windrows on an earth base.  When I visited their site a few years
ago, there were neighbors picketing out by the entrance, complaining about
foul odors.  Is that the image that we want composting to have?

On the other hand, if you're paying over $ 1 million for the land, and
another $15 million for building, concrete pad, and other site improvements,
then maybe turn around time becomes very important.  As far as I am
concerned, being a great neighbor is absolutely essential to long term
profitability and being able to provide massive benefits to society and our
environment.   I have the illusion that keeping the compost aerobic (Oxygen
> 17%), and using our Dynamic Bio-Filtering technology is absolutely
essential.  Maybe I'm wrong.  

>From a business point of view, trucking is very expensive.  And land close
to the front end and finished product markets is also expensive.  Balancing
the two can be challenging.

Then we can get into a discussion of VFA's which are phyto-toxic byproducts
of anaerobic decomposition.

Working Together to Create a Sustainable Environment,
John A. Crockett, a.k.a. Dr. Mike Robe
Mother Nature's Farms, Inc.
(845) 225-7763
http://www.magicsoil.com/
jac at magicsoil.com