Simultaneous di-oxygenation and denitrification in an internal circulation baffled bioreactor

An internal circulation baffled bioreactor was employed to realize simultaneous di-oxygenation of phthalic acid (PA) and denitrification of nitrate, which require aerobic and anoxic conditions, respectively. Adding a small concentration of succinate as an exogenous electron donor stimulated PA di-oxygenation, which produced readily oxidizable downstream products whose oxidation also enhanced denitrification of nitrate; succinate addition also stimulated denitrification. Depending on the concentration of PA, addition of 0.17 mM succinate increased the PA removal rate by 25 and 42%, while the corresponding nitrate removal rate was increased by 73 and 51%. UV/H₂O₂ advanced oxidation of PA had the same effects as adding succinate, since succinate is generated by UV/H₂O₂; this acceleration effect was approximately equivalent to adding 0.17 mM succinate.