BACKGROUNDPilot-scale studies focused on evaluating the robustness of biofilm-based anaerobic digestion processes for further application at full-scale are scarce. Therefore, the aim of this work was to evaluate the performance of a 445 L packed bed reactor (PBR) operated at different organic loading rates (OLRs between 4 and 12.5 g COD L-1 d(-1)) for the treatment of tequila vinasses. The reactor performance was correlated with the microbial dynamics to elucidate the specific role of the microbial communities in the degradation pathways that govern the process. RESULTSThe PBR was operated for 231 days under different OLRs showing a stable performance. The COD removal and methane yield were maintained throughout the reactor operation at 86-89% and 0.24-0.28 L CH4 g(-1) CODadded, respectively. Meanwhile, the highest volumetric methane production rate of 3.03 L CH4 d(-1) L-1 was reached at the highest OLR, 12.5 g COD L-1 d(-1). Regarding microbial dynamics, the Bacteria and Archaea populations were able to adapt to the OLR disturbances, favoring the interactions between syntrophic Bacteria and Methanosaeta at high OLRs. CONCLUSIONThis work contributes to the scarce information regarding anaerobic treatment of tequila vinasses at pilot-scale and demonstrates that the PBR is a promising and robust configuration that allows treating higher OLRs than currently reported technologies. (c) 2017 Society of Chemical Industry