Influence of reflux ratio and hydraulic loading on the performance of pre-denitrification BAF in wastewater treatment
回流比水力负荷对前置反硝化生物滤池工艺处理污水的影响研究

Pre-denitrification BAF (biological aerated filter) performs well in denitrification of wastewater, and reflux ratio is one of the most important factors affecting the treatment performance. The removal effficiencies of COD, NH+4-N and TN were investigated seperately at reflux ratios of 50%, 100%, 200% and 300%. The results showed that the removal efficiency of contaminants for pre-denitrification BAF was increased initially, and then decreased when the reflux ratio was larger than 200%. However, the influence on TN removal was more significant than that for the removal of COD and NH+4-N. At the optimal reflux ratio of 200%, the average removal efficiencies of COD, NH+4-N and TN were 92.67%, 90.50% and 80.50%, respectively. Maintaining the reflux ratio at 100%, the removal efficiency of contaminants for pre-denitrification BAF initially increased, and then decreased at hydraulic loadings greater than 2.08 m·h-1. At the optimal hydraulic loading of 2.08 m·h-1, the average removal efficiencies of COD, NH+4-N and TN were 91.72%, 90.29% and 74.45%, respectively. It was also demonstrated that COD, NH+4-N and TN were removed mainly in the hypoxic environment in the BAF (DN), and the average removal efficiencies were 78.48%, 68.02% and 58.21% respectively.