| Many
in-vessel composting systems are marketed today in wide price ranges
up to $15 million. They appeal to some because, being contained
in a tank, they suggest hope for odor reduction. But while odors
may exist from a preparatory stockpile of feedstock
(same at an in-vessel site), once they are part of a balanced recipe
aerobic windrow, odors disappear
in 48-72 hours.
 A
second appeal is their claim to reduce composting time. Some systems
claim to produce compost in a few days to a few weeks. Their definition
of finished quality compost is far different from ours.
Any system
which costs so much must be considered "advanced." And
don't those system designers have a lot of initials behind their
names? But we always believed product quality and profitability
were the key issues.
We
do not believe in-vessel systems achieve the quality of the Advanced
Composting System complemented by an Aeromaster turner. Here's
why:
- In-vessel
systems do not achieve the thorough mixing and blending of feedstocks
which Aeromaster turners do. This is vital to complete interaction
of carbons and nitrogens.
- Many
in-vessel systems require windrowing
and turning following ejection from the tank.
- Lack
of opportunity to make recipe adjustments once the material
is loaded in the tank.
Midwest
Bio-Systems offers two simple challenges:
1. Compare the quality of the finished compost —
Compare the results from a complete laboratory analysis, not just
by what is not in the compost (pathogens,
weed seeds, etc.), but by an analysis of what it does for the
soil and plant. Compare germination and growth tests, microbial
quality and diversity, aerobic to anaerobic
microbe ratios, humus
content, the presence of sulfides
or sulfates, conductivity,
and redox potential. We believe
that both laboratory tests and soil/crop results will demonstrate
superior product quality using the ACS system.
2.
Compare profitability — Learn what an in-vessel
system receives for its finished compost product. If it is operating
profitably, a closer look will indicate they are doing so based
on tipping fees, not by what they receive for their finished compost.
The common result is compost that is either given away or sold
at minimal prices. Price per ton is significantly higher with
lesser results in the end.
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