Biodegradation of o-nitrophenol by aerobic granules with glucose as co-substrate

Aerobic granules to treat wastewater containing o-nitrophenol were successfully developed in a sequencing batch reactor (SBR) using activated sludge as inoculum. Stable aerobic granules were obtained with a clearly defined shape and diameters ranging from 2 to 6 mm after 122 days of operation. The integrity coefficient (IC) and granules density was found to be 98% and 1,054 kg m⁻³ respectively. After development of aerobic granules, o-nitrophenols were successfully degraded to an efficiency of 78% at a concentration of 70 mg L⁻¹. GC-MS study revealed that the biodegradation of o-nitrophenol occured via catechol via nitrobenzene pathway. Specific o-nitrophenol biodegradation rates followed the Haldane model and the associated kinetic parameters were found as follows: V_max = 3.96 g o-nitrophenol g⁻¹VSS⁻¹d⁻¹, K_s = 198.12 mg L⁻¹, and K_i = 31.16 mg L⁻¹. The aerobic granules proved to be a feasible and effective way to degrade o-nitrophenol containing wastewater.