Evaluation of the C/N Ratio in Anaerobic Digestion of Organic Restaurant Residue

Fabiane Granzotto¹, Djalma dias da Silveira¹, Eduarda Holz Bracher¹, Caroline Denise Noronha de Lima¹,

Ronaldo Hoffmann¹, and Stefen Barbosa Pujol²

1. Department of Chemical Engineering, Federal University of Santa Maria, Brazil

2. Department of Soils, Federal University of Santa Maria, Brazil

Abstract: The production of urban solid waste is increasing, and, in Brazil, the organic waste comprises its majority. Proper treatment or disposal is much less applied to organic wastes, although these residues have the potential to generate biogas and biofertilizer. In this way, the C/N ratio was evaluated before and after the anaerobic digestion of the organic waste from a restaurant to verify the potential of this residue for use in biodigestion and to evaluate the effluent for the use as a biofertilizer. An anaerobic biodigester with a useful capacity of 120 L was used in a semi-continuous system with a mesophilic temperature. The C/N ratio of the affluent ranged from 19.9 to 33.2 and the effluent from 9.4 to 11.9. The data found in the literature and those of this work for the C / N ratio are in agreement.

Therefore, the studied residue has potential for direct use with no need of correction of the C/N ratio for the used process, and the generated compost demonstrated the possibility of its use in fertilization.

Key words: biodigestion, biofertilizer, degradable residue