Using a Second-Order Polynomial Model to Determine The Optimum Vinasse/Grape Marc Ratio For In-Vessel Composting

Compost Science & Utilization, (2004), Vol. 12, No. 3, 273-279

M.J. Díaz (1), E. Madejón (2), F. Cabrera (2), L. Jiménez (3) and M. De Bertoldi (4)
1. Departamento de Ingeniería Química, Facultad de Ciencias Experimentales Campus del Carmen,
Universidad de Huelva, Huelva, Spain
2. Instituto de Recursos Naturales y Agrobiología de Sevilla (CSIC), Sevilla, Spain
3. Departamento de Ingeniería Química, Campus de Rabanales, Universidad de Córdoba, España
4. Dept. of Industrial Microbiology, University of Udine, Udine, Italy

This paper evaluates the influence of operating conditions (pH, Kjeldahl-N losses, NO3--N, NO4+-N, C/N ratio and biodegradation) used in the vinasse/grape marc incubation on the properties of products obtained to determine the best incubation conditions (time and amount of vinasse proportion) to aid in the design of an in-vessel composting system. A second-order polynomial model consisting of two independent process variables was found to accurately describe, with <10% differences between experimental values and model prediction, the vinasse-grape marc incubation. The dependent variables measured were pH, Kjeldahl-N losses, NO3--N, NO4+-N, C/N ratio and biodegradation and the independent process variables were operation time and amount of vinasse. Results determined products with acceptable chemical properties, high biodegradation and germination index and minimum Kjeldahl-N losses entails operating at medium-to-short operation time (20-35 days) and medium-to-low vinasse percentages (0-20%).

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