Abstract: The invention makes possible a coking operation largely or completely eliminating waste water by converting the gas condensates obtained from the coking plant by a reverse osmosis process into a permeate which can be recycled to the coking operation, and a concentrated lye.

Abstract: The ammonia contained in ammonia- and hydrogen sulfide-containing gas mixtures is selectively removed through a gas washing with an aqueous ammonium sulfite-bisulfite solution, and recovered from the wash solution as a concentrated aqueous solution. For this purpose the coke oven crude gas is washed with an ammonium sulfite-bisulfite solution led in circulation, the surface tension of which amounts to below 80.times.10.sup.-5 N/cm, then the ammonia gas is driven away from the wash solution enriched with ammonia, e.g. by means of steam, and the released ammonia is recovered e.g. as aqueous ammonium solution through condensation of the vapor. The gas mixture is preferably purified or unpurified coke oven crude gas. In order to reduce the surface tension of the wash solution, alkyl sulfate, alkylamine, pyridine base, phenol or homologs thereof are added as surface active substance. The wash circulation is performed at between 15.degree. and 32.degree. C.