Biological Aerated Filter (BAF)
The biological aerated filter consists of a filter body, ceramsite/volcanic rock media layer (3-6mm), aeration system (microporous diffusers), water-air distribution device, and air-water backwash system. With a treatment capacity of 50-2,000m³/d, it achieves ≥80% COD removal and ≥90% ammonia nitrogen removal, featuring compact footprint (50% of traditional processes), high impact load resistance (SS≤200mg/L), and simultaneous nitrogen/carbon removal. Wastewater uniformly passes through the media layer, where attached microorganisms decompose organic matter under aeration, and NH₃-N is nitrified to nitrate. Periodic air-water backwashing (air intensity 15L/(㎡·s) + water 8L/(㎡·s)) strips off biofilm and suspended solids. Widely used in advanced treatment of mining domestic sewage (e.g., underground living wastewater), municipal secondary treatment, food processing wastewater denitrification, and biochemical treatment of chemical wastewater, suitable for low C/N ratio water purification.
