DEVELOPMENT OF A BIOLOGICALLY-BASED AEROBIC COMPOSTING SIMULATION-MODEL

A relatively simple dynamic model based on microbial process kinetics has been developed for aerobic composting. Differential equations desc ribing microbial, substrate, and oxygen concentrations, as well as moi sture and temperature profiles have been derived as a function of vess el size and aeration rate. Microbial biomass growth was described usin g Monod growth kinetics as a function of degradable substrate concentr ation, oxygen concentration, moisture content, and compost temperature . Facility and fan operating costs have been included to permit econom ic optimization of the process. Predicted results demonstrated the abi lity of the model to quantify and describe the influence of multiple i nteracting factors (temperature, oxygen, moisture, and substrate avail ability) on the process driving the composting. microbial growth kinet ics. Future development of the approach should be undertaken to provid e a robust engineering model that can be used to evaluate and design e nvironmentally sound composting facilities. An example application is presented along with data from a laboratory scale composter.