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 15.32 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:CH 4 conversion reached 0.31 ± 0.07 m 3  CH 4  kgCOD removed −1 ; COD:biogas estimated 0.45 ± 0.06 m 3  gas kgCOD removed −1 , ∼300% higher than the acclimation period. Operation remained stable at OLR  −3  day −1 , which corresponds to an SLR of 4.8 kgCOD kgVSS −1  day −1 . This limit results in an Alk bicarb .:Alk tot  ∼ 0.31 and a pH ∼ 6.51, an irreversible status that demonstrates the limits of anaerobic treatment of winery wastewater with this reactor setup.