Empirical Model and Kinetic Behavior of Thermophilic Composting of Vegetable Waste

Laboratory-scale temperature-controlled reactors were used to generate experimental data of thermophilic composting of vegetable waste. By fitting in experimental data of thermophilic composting, the obtained empirical model (also verified by F-test) appeared to be a quadratic form. The empirical model can be used to predict operating conditions (ratio of predried vegetable waste to rice husks, aeration rate, and reaction temperature and time) for thermophilic composting of vegetable waste in the subtropical region. Moreover, an innovative method for investigating kinetic behavior of thermophilic composting (an exoenzyme-catalyzed reaction followed by a multienzymecatalyzed reaction) is proposed. The two biochemical reactions of thermophilic composting of vegetable waste followed Monod-type kinetics with the specific substrate utilization rate constants k1 and k2 of 0.026 and 4.5 mg COD/mg VSS/day, respectively. Accordingly, the exoenzyme-catalyzed reaction kinetically controls the overall process of thermophilic composting of vegetable waste.