Treatment of high salinity phenol-laden wastewater using a sequencing batch reactor containing halophilic bacterial community

• To degrade 1200 mg l−1 phenol at 80 g l−1 NaCl within 9 d.
• Halophiles included Pseudomonas, Alcaligenes, Brachybacterium and Halomonas.
• Phenol-degrading bacteria comprised 63.3% of the total bacterial community.
• Phenol ring cleavage including the ortho-pathway and the meta-pathway.

Sequencing batch reactors (SBRs) were used to degrade phenol compounds efficiently; however, most investigations on such reactors have focused on fresh rather than saline wastewaters, even though saline effluents containing phenolic compounds are generated by many industries. This study assessed the performance of the aerobic SBR process in the removal of phenol as the sole substrate under conditions of high salinity. A flexible concentration of phenol could be completely degraded in SBR process, varied from 400 mg l−1 to 1200 mg l−1 at the existing of 80 g l−1 NaCl. The value of specific oxygen uptake rate (SOUR) suggested that the exiting bacteria could adapt to the phenol and salt conditions well at each stage. Cloning and sequencing of the 16S rRNA showed that the acclimated active sludge included two dominant genera: Pseudomonas and Alcaligenes. PCR detection of the functional genes suggested that phenol hydroxylase (Lph), catechol 1,2-dioxygenase (C12O), and catechol 2,3-dioxygenase (C23O) were active in the phenol-degradation process. Real-time PCR showed that the phenol-degrading bacteria comprised 63.3% of the total bacterial community.