Nitrogen removal from wastewater via simultaneous nitrification and denitrification using a biological folded non-aerated filter.

A conventional biological filter has been shown to be a viable method for removing nitrogenous compounds from wastewater, but it still has many disadvantages. In this study, a biological folded non-aerated filter (BFNAF) was designed, and its feasibility for nitrogen-loaded wastewater treatment has been confirmed. Effects of the HRT and the COD/N ratio on the performance of BFNAF were investigated. Through response surface method, when the COD/N ratio and the HRT were 5.39 and 10.83 h, removal efficiencies of NH4+, COD and TN reached maximum values of 88.62 ± 0.81%, 76.12 ± 0.57%, and 50.48 ± 1.02%, respectively. In addition, it was found that several denitrifying bacteria, such as Azoarcus, Arcobacter, Flavobacterium, along with many ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, co-existed in the community of the biofilm. All the results showed that the BFNAF could realize the simultaneous nitrification and denitrification (SND) process effectively.