Simultaneous degradation of phenolic compounds under denitrifying conditions in a UASB reactor provided with granular activated carbon

This work studied the removal capacity of a mixture of phenolic compounds (phenol, p-cresol, o-cresol) by denitrification; in addition, the effect of granular activated carbon (GAC) in the process carried out in UASB (up-flow anaerobic sludge blanket) reactors. The organic load was increased from 450 to 3250 mg C L-1d-1 by adjusting the HRT from 2 to 0.25 d in the reactor with GAC and the control reactor without GAC. The removal efficiencies of phenolic compounds increased as the organic load increased, obtaining values from 89.7 % to 95.5 % in the reactor without GAC and 95.8 % to 99.1 % in the reactor with GAC. The nitrate removal in the reactor with GAC reached 79.3 % to 98.0 % efficiencies, while the control obtained 64.8 % to 96.9 %. Finally, the maximum capacities of GAC were evaluated by adsorption isotherms, obtaining the following values (mg g-1): 164.6 for o-cresol, 134.5 for p-cresol, 110.7 for phenol, and 44.4 for nitrate. The results show the capacity of a denitrification process to remove a mixture of phenolic compounds. In addition, the reactor with GAC increased the removal efficiency of all compounds.