Lessons Learned from this
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Covers
Demonstration of a community manure digester
project
Concrete hard tops operating under pressure are very difficult to seal.
Leaks of biogas cause loss of gas production and odors on the farm. Pressure testing
before filling with manure is time consuming and expensive but apparently needed to
ensure that the sealant has been properly applied.
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Exhaust Pipe
Demonstration of a community manure
digester project
Burying the exhaust pipe and out letting it some distance from
the engine room keeps corrosion away from building and keeps noise down. Internal
combustion engines are loud. Sound control may be needed on some sites.
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System Uniformity
Demonstration of a community manure
digester project
Complete engine skids and gas handling skids that have been factory
installed to meet the specifications of the specific installation provide design and
construction convenience. The systems are put together with compatible equipment and
controls so on farm hassles are reduced.
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Temperature Control
Demonstration of a
community manure digester project
The thermometers were installed reading 3
degrees higher than reality. Checking and calibrating the instrumentation should be an
important step in start up procedures.
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Temperature Control
Demonstration of a community manure
digester project
Maintaining temperature control during the winter is important.
Frozen manure and manure that was too wet was bypassed from the digester. When the digester
feed was reduced the gas production slowed and less heat was available to heat the influent
and maintain the temperature. Either added external energy would be needed to maintain the
digester temperature or the digester would need several months and warmer weather to recover.
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Twin Digestion construction
Demonstration of a community manure digester project
The twin digester construction to avoid an excessively long digester and reasonable spans
for the concrete top is a viable design. This should make it possible to shut down and start
up each side independently and therefore easier. It is hard to divide the influent equally to
the two digesters; a flow meter along with the control device may be needed.
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