FAC.311-The Application of Laboratory Aeration Demand Testing to Facility Design-AC22.CREF

The efficiency with which aerobic bacteria consume oxygen and convert organic matter (OM) to CO2 is the primary measure of composting stabilization rates and a determining factor in air emissions.  Process conditions (primarily temperature and oxygen) and feedstock characteristics determine the efficiency of this process.  Researchers, such as McCartney, Sundberg, and others, have used highly controlled laboratory benchtop composting units to conduct peer-reviewed research on the fundamental relationships of this bio-oxidative process, but to date, lab quality benchtop units have not been generally available to help facility designers value-engineer compost facilities.  Considering the growing demand to compost challenging feedstocks in increasingly complicated regulatory environments, ECS has developed the Aeration Demand Tester (ADT) to provide designers with a feedstock specific basis-of design for their aerated composting process. The ADT consists of a highly instrumented 20-liter volume that maintains precise temperatures and air flow rates and records real-time CO2 production over a period of days or weeks.  CO2 production is stoichiometrically related to the bio-oxidation of OM and the generation of heat.  These results provide an accurate assessment of the retention time required to achieve the desired compost stability, and through the application of thermodynamic modelling, the aeration demand to provide adequate cooling to maintain the temperatures used in the test.  This presentation will include the results of ADT trials conducted to answer real-world questions posed facility designers such as: Can our stability goal be met with our designed retention time without adding amendments to our raw digestate feedstock?  What peak aeration rate is required to reliably neutralize the initially acidic pH of our food waste + yard waste mix within three days?  How low of a C/N ratio can my poultry manure mix be without overly inhibiting the bio-oxidation process and producing excessive air emissions?
Speakers: Charlie Krauter
Duration: 27 minutes
Credits: 0.5
Member Price: $30.00
Non-Member Price: $52.50
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