Abstract: An immersible filling body for the biological treatment of sewage stored in the basins of sewage treatment plants, aerated ponds and lagoons. The filling body is comprised of vertical channels for conducting the flow of a gas-liquid mixture. Each channel includes a central portion of substantially constant cross sectional area and two outer portions of variable cross sectional areas in order to produce a more vigorous communication between both the liquid and the gas and the liquid and the channel walls.

Abstract: A spherical packing element for biological film processes which is formed of a flat circular base plate having a central, throughgoing opening therein, a flat and imperforate disk reinforcing plate extending along the opening and lying in a plane perpendicular to the base plate and a plurality of spaced apart, imperforate and mutually parallel circular lamellae perpendicular to both plates, traversing the opening, and spaced apart in the direction of the diameter. The packing element has a surface area of at least 250 m.sup.2 /m.sup.3, and wall thickness of the plates and lamellae are 0.1-2 mm.