Role of aerated turbulence in the fate of endogenous nitrogen from malodorous river sediments

Artificial aeration is one of the alternatives proposed in treating malodorous rivers. However, the contribution of aeration turbulence to endogenous N-behavior is still poorly understood. In this research, a recirculating ditch was used to investigate the effects of aeration on N-behavior in terms of aeration turbulence, dissolved oxygen (DO), and sediment oxygen demand (SOD). Specifically, the Reynolds number (Re) combining with fluid field distribution characterized the disturbance from aeration. Results showed that aerated turbulence played an important role in endogenous N-behavior and that Re may be an effective means for characterizing aerated-turbulence. There was a marked decrease of ammonium concentration in the overlying water with increased aeration disturbance. Nitrate concentrations and corresponding variation rates were positively correlated with Re both in bulk- and pore-water with temperature above 20 C. Comparatively, a run with a Re=1810 was deemed as the optimized aeration disturbance in this study. Grey relational analysis indicated that the effects of Re on the behavior of ammonium and total-N prevailed over DO and SOD. This research validated the feasibility of Re to characterize aeration turbulence and the necessity to optimize aeration conditions.