A Biological Aerated Filter (BAF) is an advanced wastewater treatment technology combining bio-oxidation and filtration.It uses a porous filter media (e.g., volcanic rock, ceramic particles) as the carrier for microorganisms.Compressed air is injected at the bottom of the filter to provide oxygen for aerobic microbes.When wastewater flows through the filter media, microbes attach to form a biological film.The biological film decomposes organic pollutants (COD, BOD) into CO₂ and H₂O.Nitrifying bacteria in the film also convert ammonia nitrogen into nitrate (nitrification).The filter media simultaneously traps suspended solids in wastewater through physical filtration.It has a small footprint compared to traditional activated sludge systems.High treatment efficiency allows it to handle high-concentration organic wastewater.No secondary sedimentation tank is needed, simplifying the treatment process.The filter can be backwashed periodically to remove excess sludge and restore capacity.It adapts well to fluctuations in wastewater flow and quality (strong shock resistance).Widely used in municipal wastewater advanced treatment and reuse projects.Also applicable to industrial wastewater treatment (e.g., food, brewing, chemical).Effective in removing refractory pollutants and improving water biodegradability.Low energy consumption due to efficient oxygen transfer and compact design.Simple operation and maintenance, reducing labor and management costs.Treated water can meet strict discharge standards or reuse requirements (e.g., irrigation).Different filter media types can be selected based on specific treatment goals.As a cost-effective and efficient technology, BAF is widely adopted in wastewater treatment.