Slaughterhouse wastewater treatment by adopting AB method coupled with internal recycle biological aerated filter

Aiming at the characteristics that slaughterhouse wastewater contains organic pollution and ammonia nitrogen with high concentration, the combined technological treatment of AB method and internal recycle BAF are adopted. The test studies hydraulic retention time (HRT) of section A and section B of AB method and the effect of influent water loading on the COD removal, effect of the HRT of internal recycle BAF on NH₃-N removal effect, and recovery situation after backwash of internal recycle BAF. The result shows that for section A, when HRT is 50~55 min, and COD load is 15~18 kg/m³·d, COD removal rate is 55~60%; for section B, when HRT is 8~10h, and COD load is 0.60~0.75 kg/m³·d, COD removal rate is 75~80%; and for internal recycle BAF, when HRT is 2.0h and dissolved oxygen (DO) is ≮2.5mg/L, NH₃-N removal rate is 83%; and internal recycle BAF can be restored to normal levels in 3h after backwash.