Biodegradation of remazol black b in sequential microaerophilic-aerobic operations by nar-2 bacterial consortium

Abstract

The ability of the NAR-2 bacterial consortium, consisting of A1, C1, and L17, to degrade the azo dye model, Remazol Black B (RBB), was studied in an upflow packed-bed reactor for continuous sequential micro- aerophilic–aerobic batch operations. Continuous decolourisation was performed in a borosilicate glass col- umn (12 mm 9 20 mm) packed with surfactant-modified clinoptilolite immobilised by the NAR-2 bacterial consor- tium. In column bioreactor studies, decolourisation was observed at 45 ° C and was carried out by varying the flow rates and dye concentrations in a modified P5 medium with pH 7.0 under microaerophilic conditions. A decolourisation of 95.87 % of 0.1 g/L RBB was achieved at a flow rate of 0.2 mL/min under microaerophilic conditions by the immobilised NAR-2 bacterial consortium. An analysis of the decolourised and biodegradation products of the RBB using total aromatic amines showed that a reduction in the RBB resulted in the formation of aromatic amines. On further aerobic degradation for 15 days, the concentration of the amines dropped significantly, from an initial con- centration of 34 to 11 mg/L, following the aerobic batch treatment experiment. The findings of this study showed that SMC can be a support material for bacterial cell immobilisation in a single upflow reactor with intermittent microaerophilic–aerobic operations, and it was found to be suitable and eco-friendly for the degradation of azo dyes.