A relatively simple dynamic model based on microbial process kinetics has been developed for aerobic composting. Differential equations describing microbial, substrate, and oxygen concentrations, as well as moisture and temperature profiles have been derived as a function of vessel size and aeration rate. Microbial biomass growth was described using Monod growth kinetics as a function of degradable substrate concentration, oxygen concentration, moisture content, and compost temperature. Facility and fan operating costs have been included to permit economic optimization of the process. Predicted results demonstrated the ability of the model to quantify and describe the influence of multiple interacting factors (temperature, oxygen, moisture, and substrate availability) on the process driving the composting: microbial growth kinetics. Future development of the approach should be undertaken to provide a robust engineering model that can be used to evaluate and design environmentally sound composting facilities. An example application is presented along with data from a laboratory scale composter.

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Published in Transactions of the ASAE, v. 39, issue 1, p. 239-250.

© 1996 American Society of Agricultural Engineers

The copyright holder has granted the permission for posting the article here.

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Salaries and research support provided by state and federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University, Columbus, Ohio.