Long-term performance and stability of a continuous granular airlift reactor treating a high-strength wastewater containing a mixture of aromatic compounds

© 2015 Elsevier B.V. Continuous feeding operation of an airlift reactor and its inoculation with mature aerobic granules allowed the successful treatment of a mixture of aromatic compounds (p-nitrophenol, o-cresol and phenol). Complete biodegradation of p-nitrophenol, o-cresol, phenol and their metabolic intermediates was achieved at an organic loading rate of 0.61g COD L-1d-1. Stable granulation was obtained throughout the long-term operation (400 days) achieving an average granule size of 2.0±1mm and a sludge volumetric index of 26±1mLg-1 TSS. The identified genera in the aerobic granular biomass were heterotrophic bacteria able to consume aromatic compounds. Therefore, the continuous feeding regimen and the exposure of aerobic granules to a mixture of aromatic compounds make possible to obtain good granulation and high removal efficiency.