Thanks,  Andreas, for the information on aerated and traditional
composting.  Is there any formula that would help an authority, firm or
organization calculate whether the amount of space available relative to
organics to be composted would require an aerated approach as vs the
slower traditional approach?

I think this is an important technical decision and in the past it seems
that some cities have adopted the more elaborate aerated set-up regardless
of the amount of space at the compost site.

I guess the tricky aspect of setting up a composting plant to serve a city
or community is estimating the amount of material that will be generated
and collected.  It is not just a current estimate, as the plant has to be
appropriate for a period of time.  If cities are planning source
separation and various programs for diversion (of different components in
MSW), the amounts of the different components could change significantly.

Here in Toronto we are facing a dilemma about estimating quantities of
MSW.  The city wants to sign a contract with a waste management company in
USA to truck Toronto's garbage to Michigan landfills after our main dump
is full in a couple of years.  It would be preferable to send the waste by
rail, as otherwise there will be about 150 large trailers a day on the
road from Toronto to USA.  But that contract would require that the city
guarantee a minimum quantity of waste to be transported for years to come.
If the quantity is less, the city will have to pay for the transport at
the guaranteed level, nevertheless.  Since wet/dry separation is being
planned here, it is now hard to predict what quantities of waste would
need to be sent to Michigan in the future.

This is just an illustration of the problem of estimating future
quantities of waste in cities.

 Chris Furedy