Anaerobic digestion of winery solid waste in a two-stage membrane process: Effect of loading rate on biomethane production

Abstract

The wine industry causes a high amount of solid waste with high organic content at different parts of the production line. One of the best strategies to overcome organic solid waste management problem is anaerobic digestion, as It allows renewable energy production and waste reduction together. The OLR is considered one of the most important operating parameters in continuous or semi-continuous anaerobic operations, as it affects the overall performance of anaerobic digestion systems. Therefore, appropriate OLR determination plays a crucial role in anaerobic digestion. This study investigated the effect of OLR on the performance of a TAnMBR treating (winery solid waste) WSW in terms of biogas and biomethane production. To this end, the production of biogas and biomethane from WSW via a TAnMBR at four different OLRs (0.5 0.75 1.0 1.5 gVS/Lreac d) was investigated. Biogas production rates were 677, 850, 1265, and 566 ml/gVS and biomethane production rates were 352, 450, 679, and 251 ml/gVS respectively, during 0.5 0.75 1.0 1.5 gVS/Lreac d OLR operating conditions. Results revealed that proper biogas and biomethane production can continue until the OLR is 1.5. VFA accumulation can be considered as the main inhibition reason, at 1.5 OLR VFA/Alk ratio increased up to 1.6 with 1864 mgHAc/L VFA concentration. Additionally, phenol and sulfate concentrations were below 45 and 48 mg/L during operation, respectively, therefore it is considered that no inhibition occurred due to these parameters.