Biomethanization of Brewer's spent grain evaluated by application of the Anaerobic Digestion Model No.1

Brewer's spent grain (BSG), the residual solid fraction of the final mash process of malting, is a main waste fraction of beer production, recently considered as possible substrate for biovalorization by anaerobic digestion (AD). In this article, the biomethanization of BSG was evaluated by performing biochemical methane potential (BPM) tests. The obtained specific methane production (SMP) was 0.284 LCH4·g-1COD. The process was modelled by implementing the Anaerobic Digestion Model No.1 (ADM1) into AQUASIM software with the focus on the disintegration and hydrolysis step. The calibrated disintegration rate for BSG was equal to 0.823 d-1 and the hydrolysis rate constants varied from 0.124 d-1 for lipids to 1.056 d-1 for proteins. The obtained results showed a good efficiency in treating BSG with anaerobic digestion. The practical conversion degree of the biowaste COD into methane was equal to 81.1%, a high value for a substrate with an elevated solid content. Moreover, the estimated values of disintegration and hydrolysis rates complied with the retention time values generally adopted in an anaerobic digestor.