5-24: Effects of physicochemical pretreatments and bioaugmentation on the methane potential of poultry litter and feathers waste

Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Diana Z. Sousa, José C. Costa, Sónia Barbosa and M. Madalena Alves, IBB - Institute for Biotechnology and Bioengineering, Center for Biological Engineering, University of Minho, Braga, Portugal
Anaerobic digestion of poultry wastes constitutes an opportunity to produce bioenergy (in form of biogas) and soil fertilizer, while reducing environmental impact and promoting sustainable poultry production. The aim of this work was to assess the biogas potential of raw poultry litter (bedding material mixed with manure and waste feed) and poultry feathers. Poultry litter is rich in lignocellulose and feathers in keratin, both materials of difficult hydrolysis. Therefore, thermochemical pretreatments with lime and sodium hydroxide (at different temperatures and pressure), and bioaugmentation with hydrolytic strains, were tested to evaluate the enhancement of biogas potential from these wastes. Caldicellulosiruptor saccharolyticum, Clostridium cellulolyticum and Clostridium thermocellum were used as bioaugmentation strains in poultry litter assays; Fervidobacterium pennivorans was used to hydrolyze feathers waste. Anaerobic digestion of raw litter and feathers (with 2.5% total solids) resulted in a methanization percentage (MP) of 17±2 and 33±5%, respectively. Co-digestion of poultry litter and feathers did not improve methane production; best results were obtained for a ratio litter:feathers of 10:1 with a MP of 17±4. The major increase in methanization of poultry litter was reached after the thermochemical pre-treatment with Ca(OH)2 (90 °C, 1.27 bar, 120 minutes), with a final MP of 32±1 %. Methane production from poultry feathers could not be improved by any of the tested strategies. However, all the tested treatments contributed to a significant increase in the wastes solubilization. Therefore, the conversion of soluble organic matter to methane was the limiting step of the anaerobic digestion of poultry wastes.
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