Investigating the feasibility and the limits of high rate anaerobic winery wastewater treatment using a hybrid-EGSB bio-reactor

•High-rate winery wastewater treatment is feasible by means of a hybrid-EGSB reactor.•Maximum winery wastewater treatment limit lies at an SLR ≤ 4.8 kgCOD/kgVSS·day.•Winery wastewater treatment is promoted by a Alkbicarb.:Alktot > 0.6 and a pH > 6.51.•17 °C increase promotes removal kinetics by 68 and 71% in batch and continuous setup.•Predominance of hydrogenotrophic methanogenesis is likely using the particular seed.

Biodegradability and activity tests of winery wastewater at 37 °C using inoculum from a paper mill suggested hydrolysis as the rate limiting step with hydrogen the predominant pathway to methane. Scaling-up to a Hybrid-EGSB showed that after 100 days acclimation at moderate temperatures (20 ± 2 °C) a 70 ± 2% COD removal is achievable, applying an OLR of up to 15.32 kgCOD m−3 day−1 and an SLR of 3.83 kgCOD kgVSS−1 day−1, respectively. Conventional operation and mesophilic temperature increase improved COD removal efficiency (≤96%) while sCOD concentration met the European COD effluent standards. COD:CH4 conversion reached 0.31 ± 0.07 m3 CH4 kgCODremoved−1; COD:biogas estimated 0.45 ± 0.06 m3 gas kgCODremoved−1, ∼300% higher than the acclimation period. Operation remained stable at OLR < 39 kgCOD m−3 day−1, which corresponds to an SLR of 4.8 kgCOD kgVSS−1 day−1. This limit results in an Alkbicarb.:Alktot ∼ 0.31 and a pH ∼ 6.51, an irreversible status that demonstrates the limits of anaerobic treatment of winery wastewater with this reactor setup.