Abstract
A stochastic model was proposed for in-vessel composting processes under the non-stirred conditions, considering the inhomogeneity of three state variables, that is, content of organic compounds, moisture content, and temperature. Using the value of a stochastic quantum ε (unit of discrete change in stochastic variables) estimated on the basis of the experimental results of the temperature inhomogeneity, spatial variations of organic materials and moisture content were estimated by the model. The estimated results of them agreed well with the experimental results at the end of the experiments, and the validity of the proposed model was confirmed. It was theoretically predicted that the value of ε becomes smaller and spatial inhomogeneity is smaller when the airflow rate is set as small as possible within a permitted condition for the success of the process. On the other hand, when the value of ε is too large, probability of the breakdown of the composting process would become higher.
