Modeling the temporal degradation of municipal solid waste compost

Composting has been recognized for many years as an effective method for treatment of different types of wastes, as opposed to disposal in landfills. Finding a good method to predict the rate of degradation of compost material is a decisive factor for its successful production, marketing and utilization. This paper presents a compost kinetic model for municipal solid waste (MSW), which was developed by running a series of composting experiments in a pilot scale reactor. Experiments were conducted under different operational conditions of temperature, moisture content, carbon to nitrogen ratio (C/N), airflow rate, and waste particle size. These variables were continuously measured with time and modeled using a multiple non-linear r - gression procedure to minimize the summation of deviations between the measured and calculated values. The biodegradation of organic matter was determined by the method of ignition at 550°C. The best fit equations describing the relevant considered variables were incorporated in the general degradation model to closely meet the temporal change of these variables. Results of model verification revealed close agreement between the experimental and calculated values for different initial conditions lying inside the range of initial settings selected during the experiments. The developed model should serve as a numerical tool to optimize the initial operational conditions and to potentially improve the design procedure of compost production.