Evaluation of batch mesophilic anaerobic digestion of raw and trampled llama and dromedary dungs: methane potential and kinetic study

• Published in: Biomass conversion and biorefinery 2023-12, Vol.13 (18), p.17165-17173
• Main Authors: Fernández-Rodríguez, M. J., Mancilla-Leytón, J. M., de la Lama-Calvente, D., Borja, R.
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Biotechnology; Dung; Energy; Inoculum; Mathematical models; Methane; Original Article; Rate constants; Renewable and Green Energy; Substrates
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-021-02255-6

This research was carried out with the aim to evaluate the anaerobic digestion (AD) of llama and dromedary dungs (both untreated and trampled) in batch mode at mesophilic temperature (35 °C). The biochemical methane potential (BMP) tests with an inoculum to substrate ratio of 2:1 (as volatile solids (VS)) were carried out. The methane yield from trampled llama dung (333.0 mL CH 4 g −1 VS added ) was considerably higher than for raw llama, raw and trampled dromedary dungs (185.9, 228.4, 222.9 mL CH 4 g −1 VS added , respectively). Therefore, trampled llama dung was found to be the best substrate for methane production due to its high content of volatile solids as well as its high nitrogen content (2.1%) and more appropriate C/N ratio (23.6) for AD. The experimental data was found to be in accordance with both first-order kinetic and transference function mathematical models, when evaluating the experimental methane production against time. By applying the first-order kinetic model, the hydrolysis rate constants, k h , were found to be 19% and 11% higher for trampled dungs in comparison with the raw dung of dromedary and llama, respectively. In addition, the maximum methane production rate ( R m ) derived from the transference function model for trampled llama dung (22.0 mL CH 4 g −1 VS d −1 ) was 83.3%, 24.4% and 22.9% higher than those obtained for raw llama manure and for raw and trampled dromedary dungs, respectively.