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

Abstract

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 15.32kgCODm−3day−1 and an SLR of 3.83kgCODkgVSS−1day−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±0.07m3CH4kgCODremoved−1; COD:biogas estimated 0.45±0.06m3gaskgCODremoved−1, ∼300% higher than the acclimation period. Operation remained stable at OLR<39kgCODm−3day−1, which corresponds to an SLR of 4.8kgCODkgVSS−1day−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.