Abstract: The outgoing gas or waste water is conveyed through a gas-liquid contact apparatus in which biological purification takes place. A bubble plate-type column (2) is used as gas-liquid contact apparatus. The biomass is distributed over the plates (3) in the form of an aqueous suspension with a layer height corresponding to a liquid content per plate greater than 0.07 m.sup.3 /m.sup.2, preferably greater than 0.15 m.sup.3 /m.sup.2 of column cross-section. During the biological purification of gas, the gas to be purified is supplied at the lower end of the bubble plate-type column (2). It then flows through the plates (3) and issues again as purified gas at the top of the plate column (2). When the plate column is used for purifying waste water, the waste water to be purified is conveyed from top to bottom through the plate column (2) and is traversed by air, oxygen or oxygen-containing gas.

Abstract: A process has been invented for the preparation of aminonaphthalenesulphonic acids by the catalytic hydrogenation of salts of nitronaphthalenesulphonic acids with hydrogen in the presence of Raney nickel catalysts at elevated temperature and pressure, said catalysts comprising a combination of fresh Raney nickel catalyst and Raney nickel catalyst which has already been used in prior hydrogenation or hydrogenations.

Abstract: A bio-mechanical impact protection is provided in a depressed steering wheel wherein a shock absorbing element is tiltably mounted on the steering wheel hub for tilting into frontal disposition if the steering wheel is bent down on impact. In the frontal disposition the element intercepts the horizontally accelerated and propelled driver in flat surface-to-surface contact, offering the full-thickness of the element for compression and impact energy dissipation.