Abstract: To ensure that with a method of aerobic decomposition of organic solids in which the solids to be composted are fed in the top of a compost tower and discharged from the bottom to be preferably re-used as a covering layer while a gaseous fluid containing oxygen is introduced into the compost tower, any odor nuissance is avoided, the fluid withdrawn from the compost tower after passing at least a part of the composing solids is returned to the decomposition tower independently on the pressure conditions prevailing in said decomposition tower, wherefrom additionally results a process course more advantageous in terms of energy.

Abstract: An apparatus for the aerobic decomposition of garbage, sludge, and similar organic waste materials having a reaction container (10) with vertically descending walls for the material to be decomposed, a discharge opening (12) extending over the entire cross section of the container (10), discharge elements (14) extending over the entire area of the discharge opening, and a removal device below the opening extending over the entire area of the discharge opening. A bi-directionally driven conveyor belt (16) transports the material to be removed from the discharge opening (12) into a first receptacle (22) which receives the material that has not been adequately purified or a second receptacle (24) for purified material. The conveyor belt (16) is preferably provided with cleansing devices (26).

Abstract: In order to obtain a more intense and quicker sewage purification and a better retaining of the activated sludge flocks in an activated sludge system with aeration tank and subsequently arranged secondary settler, the aeration tank is constructed as a sealed pressure reservoir (10) to which oxygenous gas can be supplied under pressure for dissolution in water, where the secondary settler is a flotation basin (24) and the pressure from the pressure reservoir (10) is available for flotation.

Abstract: Waste water and sludge is supplied through an inlet 12 to a flotation basin 10 where a skimmer 14 collects floating solids and sweeps sunken solids into a bottom discharge trough. Water from the basin is drawn off through a line 16 and fed by pumps 18, 20 into an air pressurized container 26 through an ejector 24 which draws in and dissolves the compressed air in the water by aspiration or eduction. The air saturated water is then fed back into the basin through valves 42, 44 where the reduced pressure releases the air in the form of micro-bubbles, which reduce the surface tension of the waste water to release sludge particles and float them to the surface for skimming off.

Abstract: An inexpensive method for drying and sterilizing sewage sludge that has previously gone through a preliminary drying process and has, on the average, a solid matter content ranging between 15 and 35% and a maximum content of 40%. The sewage sludge is dried and sterilized by breaking it into ball-like particles having diameters ranging from 1 to 10 mm and coating these particles with quicklime. The entire process can be performed using a paddle mixture. The quicklime not only reacts with the surfaces of the particles so coated but also penetrates into their interiors. The resulting chemical reaction (H.sub.2 O+CaO T Ca(OH).sub.2) dries and sterilizes the sludge, without the necessity of applying heat from an external source, directly to produce a granular product which, for example, can be used as an agricultural fertilizer which can be scattered by a conventional fertilizer spreader.