Phenol rich wastewater treatment using an aerobic granular sludge SBR

Abstract

Phenol can be removed from wastewater by biological treatment, which is generally preferred to physical or chemical treatment methods, because of lower costs and the possibility of complete mineralization. Many bacteria are capable of using aromatic compounds such as phenol as the sole source of both carbon and energy. While phenol, wastewater are usually treated in continuous activated sludge processes, these systems are known to be sensitive to high phenol loading rates and to fluctuations in phenol loading. Formation of microbial granules from activated sludge flocs, under aerobic conditions is currently an active area of investigation for developing new generation wastewater treatment plants for high strength organic wastewater, bioremediation of toxic aromatic pollutants including phenol, toluene, pyridine and textile dyes, removal of nitrogen, phosphate and adsorption of heavy metals. Aerobic granules have been successfully cultivated, previously, in SBR systems from flocculated activated sludge fed with acetate as the sole carbon source. The main objective of this study was to investigate how phenol loading affected the structure and activity of aerobic granules. The results indicated that phenol loading exerted a profound influence on the structure and activity of the aerobic granules. Compact granules with good settling ability were maintained at loading up to 3.0 kg phenol m-3 day-1, and structurally weakened granules were observed at the highest loading of 3.7 kg phenol m-3 day-1. Phenol-degrading aerobic granules possess high activity, compact structure and good settleability, and have the potential to treat wastewater with high phenol loading in sequential system at relatively low hydraulic retention times.