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Performance and microbial dynamics in packed-bed reactors during the long-term two-stage anaerobic treatment of tequila vinasses

Toledo-Cervantes, Alma, Guevara-Santos, Nora, Arreola-Vargas, Jorge, Snell-Castro, Raúl, Méndez-Acosta, Hugo Oscar
Biochemical engineering journal 2018 v.138 pp. 12-20
anaerobic digestion, biogas, methane production, methanogens, vinasse, volatile fatty acids
This work contributes to the scarce information regarding the use of fixed-growth reactors for two-stage anaerobic digestion. Two up-flow continuous packed-bed reactors connected in series were evaluated during 335 days for tequila vinasses treatment. Different organic loading rates (OLRs) were evaluated ranging from 7.7 to 29 g-COD L−1 d−1 for the acidogenic reactor (A-reactor) and from 2.7 to 12 g-COD L−1 d−1 for the methanogenic one (M-reactor). Results showed that the A-reactor remained stable under OLRs up to 19.4 g-COD L−1 d−1, while fermentative products (volatile fatty acids, VFAs) were effectively transformed to biogas in the M-reactor (∼87% of the theoretical methane yield). A higher OLR (29.0 g-COD L−1 d−1) in the A-reactor resulted in an overproduction of VFAs (7.1 g-acetic acid L−1), which decreased the diversity and evenness of methanogenic populations in the M-reactor. Overall, similar methane yields to those previously reported for tequila vinasses were obtained but at higher OLRs.