Abstract: The process for the removal and qualitative analytical determination of cyanide in cyanide-contaminated soils consists of introducing biologically degradable organic acids into the soil while blowing a gas stream therethrough and subsequently oxidizing the hydrocyanic acid liberated thereby, until no hydrocyanic acid and nor ammonia are detectable in the emerging gas stream. Preferably, the process is carried out by blowing carbon dioxide and compressed air into said soil. The process is also suitable for indirectly detecting pollutants associated with cyanide.

Abstract: A method is disclosed for purifying waste gases containing extremely finely dispersed pollutants in dust form and pollutants in gas and vapor form, particularly for purifying waste gases produced in chemical vapor phase reactions during the manufacture of optical waveguide preforms. In a first step, dust is extracted in a dry, coated fabric filter (1). The gaseous and vaporous pollutants are then absorbed in a gas scrubber. During this gas-scrubbing process, as soon as the absorption liquid circulating in an absorption-liquid circulation system reaches a pretermined pollutant concentration, part of the absorption liquid is withdrawn from the absorption-liquid circulation system and detoxicated in a separate detoxication circulation system. The part withdrawn is simultaneously replaced by fresh, unpolluted absorption liquid.