Wastewater treatment facilities having biofilm contact and solid-liquid separation functions are disclosed, wherein a biofilter unit having biofilm contact, inclination plate precipitation and de-filming functions comprises an inclination plate settler formed with a plurality of inclination plates (2), each plate spaced in parallel relative to water surface at a predetermined downward angle and a predetermined distance apart, and spacings formed by the plates (2) are filled by biofilm media (3,3a) formed with specific surface-increased and bio-affinity materials so that micro-organisms can attach and grow in the shapes of biofilms therein, and de-filming means for separating biofilms attached to and grown on the biofilm media (3, 3a) and solids deposited on the surfaces of the inclination plates (2) by applying shearing force to biofilm media (3, 3a) and inclination plates (2).