Denitrification biological filter as tertiary treatment for nitrogen removal
反硝化生物滤池深度脱氮机理

The mechanism of nitrogen removal from wastewater by denitrification biological filter(DNBF) and the related influencing factors were investigated.The results showed that the start–up period of the DNBF was performed when ran after 14 days,and the removal efficiencies of NO-3-N and TN were 80%~88% and 76~80%,respectively,while the removal efficiency of COD was over 80% in the laboratory-scale experiments.In stable running period of the DNBF reactor,the removal efficiency of NO-3-N and TN kept stable with the removal efficiency of 70%~85% and 47%~64%,respectively,when the water temperature was 20~29℃,hydraulic loading was 1.5~2 m3/(m2·h),and COD/TN was 3.7~4.5.Meanwhile,a little NO-2-N accumulated in the effluent of DNBF.The level of NH+4-N was approximately unchanged through the filter,while the level of NO-2-N accumulated from the bottom to 40 cm of the filter layer,and then kept stable.