Effect of shear velocity and feed concentration on the treatment of food waste in an anaerobic dynamic membrane Bioreactor: Performance Monitoring and microbial community analysis

The formation of the dynamic membrane (DM) in an anaerobic dynamic membrane bioreactor (AnDMBR) treating food waste was, previously, found to be beneficial to the stable performance of an anaerobic digestion system. This study examines the effect of shear velocity and feed concentration on the performance and microbial community of an AnDMBR treating food waste. The shear velocity was varied from 0.04 to 1.74 m/h, using three different feed concentrations (50, 80, and 100 g-COD/L). The highest average methane production rate of 2.6 L-CH₄/L/d was achieved at a feed concentration and shear velocity of 100-g COD/L and 0.34 m/h, respectively. Increasing shear velocity, within certain limits, is beneficial to AnDMBR systems, promoting better mixing, substrate-biomass interactions, and DM layer formation. Methanosarcina flavescens proliferated (69%) at high shear velocities when acetic acid was the major volatile fatty acid. The abundance ratio between Bacteroidetes and Firmicutes showed a linear relationship to methanogenic performance.