Nafise Mousavi - School of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
Ghasem D. Najafpour - School of Chemical Engineering, Babol Noshirvani University of Technology, Babol, Iran
Zeinab Bakhshi - School of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran
Roya Pishgar - School of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran

Effect of increase in phenol concentration on performance of anaerobic baffled reactor in terms of chemical oxygen demand (COD), phenol and COD removal efficiency and biogas productions was investigated.Furthermore, stability of the reactor with respect to the chemical shock load was monitored. The anaerobicbaffled reactor was continuously operated with synthetic wastewater. The obtained results showed that adopted sludge improved the reactor performance. The start-up strategy used for this process has achieved to the targeted goals while the active microbial population was retained. For the initial stage of operation, therewas no phenol present in the system. Then, the phenol concentrations were gradually and stepwise increased from 10 to 800 mg/L at hydraulic retention time (HRT) of 6 days. At loading rate of 0.5 g COD/L/day, maximumphenol removal efficiency of 96% was achieved. COD removal efficiency was quite high in the first compartment of baffled reactor, while the efficiency and the COD removal gradually dropped in the second and third compartments. In the bioreactor, low value of pH in the first compartment was due to acid generated by the acidogenic bacteria.

Phenol · Anaerobic baffled reactor · Acidogenic bacteria · Industrial wastewater · Biodegradation