Abstract: A process for purifying waste water form a vehicle washing installation and returning the purified water to the installation is described. The process circulates the collected waste water by negative pressure generated by a water jet pump. The pump has a water seal provided by a portion of the water after purifying.

Abstract: In order to separate oil from an oil-water mixture and in order to reduce the level of pollution in the water which is recovered, to prevent environmental pollution, the mixture is conducted over a plurality of inclined planes (18, 20, 22, 24) which are arranged at an acute angle relative to each other, in a housing 12, provided with a fleece 30 which repels oil. Thereby, the water penetrates through the fleece and is fed at the lowest point of one of those planes to a collection device (34, 36, 38, 40, 42) whereas the oil is collected from above the fleece at the lowest point of the bottom most plane 24.

Abstract: A method and apparatus for removing solid and/or liquid matter containing harmful substances from the ground or from surfaces of liquids. A vacuum up to 0.1 bar is generated by a water jet pump, whereby the matter can be sucked up even over differences in height of almost 10 meters. The water jet pump is arranged in a closed water circulation system which uses a centrifugal pump for its drive, preferably a fire-extinguishing pump. In order to prevent the harmful substances from getting into the water circulation, a collecting vessel is arranged in the suction line for the matter containing harmful substances.