therbligs and utils -Reply

My understanding is that one of the major problems with using
composted industrial or municipal wastes for land amendment is the
nasty things that occasionally show up in these sources.  This is also
true of sewage sludge (which is commonly applied to acreages).   On a
farm, the creator of the compost is usually the end user as well.   This
person has the incentive to manage the composting process to produce
a safe and useful product.   
Municipal waste, sewage and many industrial wastes, have much more
variable and unpredictable compositions -- often including toxic
substances that either will adversely affect the composting process
itself, or which are still intact, and harmful, in the final product.   This lack
of control over what goes into the composting process mandates that
the end product be monitored very carefully.   Unfortunately, there are so
many stable, harmful substances around that it is very difficult/costly to
screen for them all.
A particular industrial waste stream, where the composition was known
and stable over time, might be a suitable candidate for composting in
combination with agricultural "wastes", but I am leery of jumping into
wide-scale use of compost from mixed municipal and/or industrial