Sequential nitrification–denitrification process for nitrogenous, sulfurous and phenolic compounds removal in the same bioreactor

•4-Methylphenol, sulfide and ammonium oxidation by an aerobic granular sludge.•Aerobic granular sludge showed metabolic capability to denitrify.•Elemental sulfur produced as strategy of nitrification–denitrification coupling.•Removal of 4-methylphenol, sulfide and ammonium in the same bioreactor.•Ammonium was biotransformed to molecular nitrogen. The kinetic and metabolic behavior of an aerobic granular sludge to nitrify, denitrify and nitrify–denitrify was evaluated in batch cultures. In nitrification control, ammonium, 4-methylphenol and sulfide were consumed efficiently (∼100%) and recovered as NO3-, CO2, S0 and SO42-, respectively. In denitrification control, S0 and nitrate were efficiently consumed and recovered as SO42- and N2, respectively. Sequential nitrification–denitrification process was evaluated by applying oxic/anoxic conditions. Ammonium, 4-methylphenol and sulfide were oxidized to nitrate, CO2 and mainly S0, respectively, under aerobic conditions. After that, anoxic conditions were established where S0 reduced all nitrate to N2, with molecular nitrogen yield (YN2) of 1.03±0.06mg/mg NH4+–N consumed. This is the first study to show the capability of an aerobic granular sludge in simultaneous removal of ammonium, 4-methylphenol and sulfide by sequential nitrification–denitrification process in the same bioreactor.