TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: Wastewater sequentially flows from the first tank to the second tank and from the second tank to the third tank. Continuous aeration within the third tank enables dense microbial colonies to develop on the engineered filter media and consume organic material, retain nutrients, and consume and/or retain pathogens using oxygen provided through aeration of wastewater. Continuous aeration within the third tank inactivates pathogens by creating an environment inhospitable with their viability.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: The first tank and the second tank are formed by a common wall (22) in a single vessel (18). The first tank is adapted to maintain a constant volume of wastewater, and adapted to retain undissolved substances that both sink to the bottom of the first tank and float to the surface of liquid in the first tank. It is also adapted to homogenize entering wastewater with liquid within the first tank so that liquid discharged from the first tank is homogenized and free of pollutants and pathogens. Dosing parameters of the pump and control system of the second tank are selected to develop, facilitate, optimize and maintain conditions in the third tank that oxidize organic materials, retain solids, reduce nutrients, and inactivate pathogens. The third tank includes a holding chamber having an open mouth, a hanger plate (46) extending across the open mouth and forming a medial opening, a vertically extending wall disposed about the medial opening, an effluent outlet about the medial opening, an inlet through the vertically extending wall, an outer shell extending upwardly from an upper edge of the holding chamber, an access opening in the outer shell, and an access cover (56). The engineered filter media is suspended from the hanger plate into the holding chamber through openings in the hanger plate. Wastewater enters the third tank at frequencies, intervals, volumes, and rates that enable dense concentrations of wastewater-treating microbes to develop in liquid in the third tank, the microbes are continually suspended in the third tank by action of the aerator, and the microbes consume organic material, retain nutrients, and consume pathogens. The engineered filter media provides a barrier to retain solids, microbes, and pathogens within the third tank.