Aqueous effluents from a process fo

Aqueous effluents from a process for gasifying carbonaceous materials may contain environmentally unacceptable compounds like hydrogen cyanide, ammonia, and compounds thereof, and dissolved salts and compounds of heavy metals and sulfur compounds. These compounds are removed from the aqueous effluents of the process for gasifying carbonaceous materials by recycling the aqueous effluents to the gasifier wherein the compounds are oxidized, reduced, or decomposed into environmentally innocuous compounds that can be released to the atmosphere or removed from the gasification process in the residue.