Development and characterization of the 2,4,6-trichlorophenol (2,4,6-TCP) aerobic degrading granules in sequencing batch airlift reactor

• Glucose and acetate were used as co-substrates to promote granule formation.
• The specific degradation rate of 2,4,6-TCP peaked at the concentration of 400 mg L−1.
• EPS contents of the 2,4,6-TCP aerobic degrading granules decreased compared with seed sludge.
• The fluorescence and components of EPS was changed identified by 3-D EEM.

2,4,6-trichlorophenol (2,4,6-TCP) aerobic degrading granules were successfully developed in the sequencing batch airlift reactor. The key strategy used in cultivation of the granules was dosing glucose and acetate as co-substrates. After granulation, average concentrations of 2,4,6-TCP and COD in the effluent were less than 8 mg L−1 and 59 mg L−1, respectively. The removal efficiencies of 2,4,6-TCP and COD were above 93% and 90%, respectively. The specific degradation rate of 2,4,6-TCP peaked at 61 mg 2,4,6-TCP g VSS−1 h−1 when inoculated at the concentration of 400 mg L−1. The extracellular polymeric substance (EPS) contents of the 2,4,6-TCP aerobic degrading granules were decreased compared with the contents in seed sludge. Two peaks attributed to the protein-like fluorophores were identified by three-dimensional excitation emission matrix (EEM) fluorescence spectra. The decrease of fluorescence parameters, e.g., peak locations, intensities, indicated quenching effect of 2,4,6-TCP on the EPS fluorescence. Meanwhile, the shift of peak position indicated chemical changes of the EPS.