Abstract: The present invention relates to the biological treatment of waste water using microorganisms whose living conditions are maintained by addition of oxygen into a contact path. An underwater support frame has a double-walled duct arranged as a contact path such that the duct is placed angularly towards a surface of the water. The duct is made for holding air bubbles to prevent the premature rise of the air bubbles added by an aerator providing air at the beginning of the contact path. The contact path has a suction point at an end which is connected via a fresh organism pipe with the aerator. A connection piece connects the aerator to a suction pipe at the beginning of the contact path. The other end of the suction pipe is connected to a flowing-in opening located at a distance from the aerator contrary to the flow direction, for supplying contaminated water to the aerator before the water actually reaches the contact path.

Abstract: A lightweight self-sealing flexible door for closing the end of a horizontal coke oven, which door comprises an outer assembly that includes a thin flexible plate and an inner plate assembly that extends into the oven and is supported by the outer assembly. Self adjusting pressure-distributing means associated with the exterior of the flexible plate continuously exert pressure at a plurality of spaced locations adjacent the outer periphery of the flexible plate to cause it to freely flex and urge sealing means adjacent the inner periphery of the flexible plate to substantially sealingly engage the surface of the frame of the oven as the frame is caused to warp and distort by the thermal cycling that occurs during operation of the coke oven. Latching devices hold the door in position against the oven frame and apply pressure upon the pressure-distributing means.

Abstract: A lightweight, flexible oven door for horizontal coke ovens consisting of a thin-walled, flexible sealing plate, door body, a coking plate assembly extending into the oven from the sealing plate door body, knife edges mounted on the inner periphery of the sealing plate door body and adapted to be pressed against the coke oven door frame, and a plurality of flexible pressure-balancing lever systems that cooperate with the door locking bar assemblies and locking hooks. Each of the flexible pressure-balancing lever systems applies pressure at several points along the outer periphery of the sealing plate door body to press the knife edges on the underside thereof against the door frame to seal the oven against the atmosphere. Each of the pressure balancing lever systems includes a plurality of flexibly interconnected levers.