Improved Anaerobic Degradation of Phenol with Supplemental Glucose

In this study, phenol degradation was investigated, with and without glucose as a cosubstrate, in batch and continuous studies. The two 2-L lab upflow anaerobic sludge blanket reactors were operated at a constant hydraulic retention time of 12 h with a gradual stepwise increase in phenol concentration from 105 to 1,260 mg/L. Batch studies showed that a 1,000-mg/L glucose supplement provided the fastest phenol removal and sludge acclimation. The effect of the glucose supplement was assessed based on microbial acclimation and granulation, phenol degradation, and resistance to shock loading. The reactor with the 1,000-mg/L glucose supplement had a shorter start-up and granulation period (4 months, compared to 7 months for the reactor without glucose supplement), larger granule size (2.76 mm, compared to 1.77 mm), and higher phenol removal efficiency under steady-state operation at 6-kg phenol-COD/L⋅day (98% compared to 88%). The reactor with the glucose supplement also exhibited a higher resistance to shock load or temperature change and faster recovery than the reactor without a glucose supplement.