Abstract: A trickling filter for treating and purifying wastewater, including a bed of filter media adapted to receive and support aerobic bacteria for reacting with the wastewater, and rotating radial areas for distributing the wastewater over the surface face area of the bed of filter media. Drainage blocks for collecting treated wastewater and reacted air are disposed below the bed of filter media collection channels for collecting air and treated wastewater from the drainage blocks. Air-discharge ducts are connected to the collection channels for discharging the reacted air to a scrubber, and water-discharge ducts are connected to the collection channels for discharging the treated wastewater from the filter. Fans create a negative air-pressure flow through the filter media collection channels, vent pipes, and the air-discharge ducts to draw the reacted air to a scrubber for filtering the reacted air.