Numerical simulation of composting process for mixture of organic fraction of municipal solid waste and poultry manure

- Five kinetic parameters in the proposed kinetic model were estimated.
- Test of the model was performed with two independent sets of experimental data.
- Very good agreement between experimental and model data was achieved.
- Organic matter conversion was the most accurately predicted dynamic state variable.
- Optimal value of initial moisture content was determined.

The objectives of this study were the following: to combine nth-order kinetic model with mass/heat balance equations and apply mathematical model on the composting process for a highly heterogeneous mixture of organic fraction of municipal solid waste and poultry manure, to estimate the kinetic parameters, to test the mathematical model with two independent sets of experimental data, to determine the optimum value of initial moisture content and to identify the key kinetic parameters. Experimental results showed that used volume of reactor with a thermal insulation allowed the self-heating of the substrate. The effect of temperature on the reaction rate constant was described by the following equation, kT = 0.015 × [1.018 − 2.8−0.002(T − 20)]. Obtained value of the reaction order was 1.6. Comparisons of experimental and model data for four dynamic state variables showed very good agreement during the process. Organic matter conversion was the most accurately predicted dynamic state variable. The optimal value of initial moisture content was determined (45%). The sensitivity analysis showed that two of five parameters have significant impacts on the model results.