Bioprocessing of broiler feathers to produce biomethane

SUMMARY Feathers are among the main by-products of the poultry meat industry and are a serious environmental and health liability, with millions of tons being burned or buried annually. However, given their protein nature, they can be used as an energy matrix based on methane-rich biogas, the so-called biomethane. In theory, energy conversion is very cost-effective and would be employable to generate heat or electricity for the producer or the industry. This review presents biotechnological aspects to increase the production of methane-rich biogas (MRB). Topics such as feather quality, keratin hydrolysis (by keratinolytic microorganisms, by alkali and by reducing agents), keratin extraction by rapid vapour explosion, methane production, inoculants for anaerobic digestion and ammonia stripping are addressed.