The effect of organic loading rate on VFA/COD ratio for methane production from an EGSB reactor

The present study evaluated the effect of organic loading rate (OLR) on VFA/COD ratio for continuous production of methane using an expanded granular sludge bed(EGSB) reactor for 200 d. Reactor performances were studied in treating high OLRs ranging from 4.91 +/- 0.54 to 16.79 +/- 1.62 g-COD l(-1)d(-1) of glucose-based synthetic wastewater in a mesophilic condition. Results showed that performance of anaerobic fermentation system was distinctly influenced by OLR in terms of organic removal efficiency, VFA yield, methane production rate and system stability.Acetic and propionic acids accounted for 80-90% of total VFA, and presented highest VFA concentration and composition of VFA showed minor changes with OLR variation. Moreover, an increase in OLR increased VFA/COD ratio in the whole operation period and high VFA/COD ratio could inhibit methanogenesis at high OLR (16.79 +/- 1.62 g-COD l(-1) d(-1)).