Phenolic wastewater: Effect of F/M on anaerobic degradation

Effect of the ratio of food to microorganism (F/M) ranging from 0.25 to 2.0 and nature of sludge on methanogenesis of phenol in the batch reactors has been evaluated. Unacclimatized flocculant sludge and acclimatized granular sludge were used as seed inocula (microorganisms) in two different sets of experiments. The degradation profiles of phenolic COD conformed to logistic growth model. Lag phases of 10 days with flocculant sludge and upto 32 days with granular sludge followed by accelerated rate of CH4 generation were noticed. Methane generation rate constant (k) has been found to vary from 0.17 to 0.21 d-1 and 0.10 to 0.18 d-1 with flocculant and granular sludges respectively. The F/M ratio also influenced the biochemical methane potential (µb) and the sludge activity [mL CH4 or g CH4-COD formed/g VSS (sludge)]. µb at 80 days (µb80) with flocculant sludge ranged from 0.18 to 0.95 while µb at 112 days (µb112) with granular sludge ranged from 0.80 to 1.04. µb80 was maximum at F/M = 0.75. The trend of slu...