Biodegradation of benzene-toluene-xylene in petrochemical industries wastewater through anaerobic sequencing biofilm batch reactor in bench scale

 This study aims to evaluate the performance of the anaerobic sequencing batch biofilm reactor (ASBBR) for biodegradation of Benzene-Toluene-Xylene (BTX) that is present in petrochemical synthetic wastewater. 

 A laboratory-scale ASBBR was used to treat a synthetic substrate mixture representing petrochemical wastewater that contained BTX. The operation schedule was: Fill time: 10 minutes, reaction time: 22.8 hours, settling time: 60 minutes, and decant time: 10 minutes, at 35΀C. The BTX samples were analyzed by gas chromatography-flame ionization detector (GC-FID) equipped with head space. 

 After reaching to stable operation, the reactor was exposed to influent BTX concentrations of 5, 20, and 50 mg/l, with overall organic loading rate of 3 g COD/l.d resulting in 61, 79, and 50% removal efficiencies for the BTX, respectively. At this time, the removal efficiencies for COD were 75, 90, and 70%. 

 The optimum BTX removal of 79% was achieved in 3 g COD/l.d and HRT of 3.8 days, at influent BTX concentration of 20 mg/l. Thus, it could be concluded that ASBBR was a feasible, efficient, and consistent technology for treatment of petrochemical wastewaters containing BTX. The ASBBR might be an alternative to intermittent systems as well as batch systems due to its superior operational flexibility.