Laboratory-scale Experiment for an Active-stage Composting Process under the Same Material and Operating Conditions

We conducted a laboratory-scale composting experiment with forced aeration using two fermenters with the same shape and geometry under the same material and operating conditions to certify the reproducibility and construct a mathematical model for the proposed composting process as an ecosystem phenomenon. Overall, the reproducibility of the composting process was relatively good, although small differences in the temperature and heat generation rate between the two fermenters occurred after 100 h, and these differences gradually increased toward the end of the experiment. Based on these results, it seems feasible to simulate the composting process with a deterministic model to examine the behavior of the entire system for the purposes of basic system design. We propose a deterministic model for heat and mass transfer in the composting process, emphasizing that the transformation process of released biochemical energy to heat involves an “energy dissipation mechanism” as a successive substrate decomposition process. The simulated model results of the temperature, moisture content, weight, oxygen concentration, and heat generation rate were in fairly good agreement with the experimental results. However, the course of the heat generation rate over time, that is, the reaction rate at any height in the vertical direction, somewhat differed from those estimated by the measured temperature profile