In Europe sheep wool is a by-product of meat and milk production as it is not of sufficient quality for the textile industry and consequently mostly represents waste. Alternative environmentally friendly methods are being sought in order to improve waste management of sheep wool. One of the options of utilizing waste wool is the production of biogas. Due to the composition of sheep wool, anaerobic digestion is a rather demanding process. The main protein of sheep wool is keratin, which is hard to degrade, so before starting biogas production, sheep wool must be pre-treated. One option is microbial pretreatment with keratinolytic microorganisms. In this research, keratinolytic microorganisms that would enable the successful pretreatment of sheep wool before anaerobic decomposition and thus increase the production of biogas from waste sheep wool were tested. Keratinolytic strains were isolated under the sheep wool compost pile and tested for keratinolytic activity. We pretreated sheep wool with the two most active strains and the coculture of both strains and then used it as a substrate for biogas production in the test of biomethane potential. We found that biogas can be produced from waste sheep wool and that microbial pretreatment with keratinolytic microorganisms has a positive effect on methane production. At the same time, we found that also thermal pretreatment increases methane production. The most effective mixture for methane production turns out to be the sheep wool, which has been thermal treated and pre-treated with the keratinolytic isolate S302 (Bacillus sp.).
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