Culture of denitrifying phosphorus removal granules with different influent wastewater

Abstract

Fed with three different kinds of influent, i.e. sodium acetate-based synthetic wastewater, synthetic wastewater with 10-mg L−1 Ca2+ ions, and raw domestic wastewater, respectively, compact of different influent wastewater on aerobic granulation was investigated in three sequencing batch reactors (corresponding to R1–R3) operating in an alternating anaerobic/oxic/anoxic mode. As a result, denitrifying phosphorus removal granules with an average diameter above 600 μm were successfully cultivated within 42 d when inoculated with flocculent sludge. The granules showed some characteristics, e.g. low in moisture content, high in specific gravity, and specific oxygen uptake rate. Reactors’ performance throughout operation presented that effluent concentration of COD was always lower than 40-mg L−1; TN, NH4+-N, and TP was often lower than 1-mg L−1. In addition, cycle test displayed that efficiencies of COD, NH4+-N, TN, and TP removal in R1–R3 reached up to 90.25, 92.98, 92.96%; 99.29, 99.57, 91.70; 90.83, 92.80, 89.56%; 94.06, 96.76, 90.71%, respectively, the maximal specific phosphorus release rate was 14.34, 8.32 and 2.32 mg P g MLVSS−1 h−1 in R1–R3, respectively, and the maximal specific phosphorus uptake rate was 14.13 mg P g MLVSS−1 h−1 in R1 and 2.34 mg P g MLVSS−1 h−1 in R2, respectively.