Improved anaerobic digestion of a thermally pretreated mixture of physicochemical sludge; broiler excreta and sugar cane wastes (SCW): Effect on organic matter solubilization, biodegradability and bioenergy production

ABSTRACT

Thermal pretreatment effect of a mixture of organic wastes (physicochemical sludge, excreta of broiler chickens and sugarcane wastes (SCW)) in the solubilization and biodegradability organic matter as well as bioenergy production by anaerobic digestion was evaluated. Two different mixtures of physicochemical sludge, excreta of broiler chickens and SCW (70%, 15%, 15% and 60%, 20%, 20% of VS, respectively) were treated at different temperatures (80°C, 85°C and 90°C) and contact time (30, 60 and 90 min). Results indicate that, organic matter solubilization degree increased from 1.14 to 6.56%; subsequently, in the anaerobic digestion process, an increase of 50% in the volatile solids removal and 10% in biogas production was observed, while, retention time decreased from 23 up to 9 days. The results obtained were similar to pilot-scale. In both experimental scales it showed that the synergy produced by the simultaneous anaerobic digestion of different substrates could increase bioenergy production up to 1.3 L bio g⁻¹ VS removed and 0.82 L CH₄ g⁻¹ VS removed. The treatment conditions presented in this study allow for large residue quantities to be treated and large bioenergy quantities to be produced (10% higher than during conventional treatment) without increasing the anaerobic digester volume.

KEYWORDS:

• Anaerobic digestion
• bioenergy production
• organic matter solubilization
• thermal pretreatment

Acknowledgments

The authors acknowledge the support via use of the infrastructure of the Environmental laboratories of the postgraduate of the Tecnológico Nacional de México/Instituto Tecnológico de Orizaba.

Funding

Nava-Valente acknowledges a PhD scholarship from the Council of Science and Technology of Mexico (CONACyT) with number (CVU/grant holder): 332980 /332980.