Catechol biodegradation by a novel hybrid anoxic biofilter.

In this study, simultaneous catechol biodegradation and nitrate removal were successfully achieved in a hybrid anoxic biofilter (HAB). The maximum biodegradation concentration of catechol by HAB, was determined 1,000 mg/L. However, optimum conditions of HAB for biodegradation of catechol were determined in catechol and nitrate concentrations of 750 mg/L and 140 mg/L-N, respectively, and a hydraulic retention time of 18 h, which corresponded to organic loading rate of 1.89 kg COD/m3. d and COD/N of 2.32. The low COD/N ratio is related to nitrogen cycling and reflected N2O flux within denitrification biofilters. Due to the use of a biofilter in this process, despite the concentration of MLSS above 3000 mg/L in the suspended growth section, HAB was capable of producing effluent with low turbidity (0.8 ± 0.5 NTU), without the need for any secondary sedimentation basin. Therefore, HAB process offers an efficient way for wastewater treatment with high concentration of aromatic compounds and nitrate in anoxic conditions and providing environmental standards for wastewater discharge.