Abstract: A method for operating a continuous wet oxidation system for destroying cyanide in caustic cyanide and metal wastes which scale upon heating. Raw waste is introduced into the wet oxidation reactor without heating while a mixture of heated dilution water and oxygen containing gas is introduced into the reactor by a separate inlet. The reactor is fitted with a pair of valved effluent lines and corresponding valved lines for introducing dilute mineral acid into each effluent line at system pressure. Oxidized effluent and offgases exit through a first effluent line while dilute mineral acid flows through a second effluent line into the reactor to prevent scale buildup. Periodically the flows are alternated such that oxidized effluent and offgases exit through the second effluent line and dilute mineral acid flows through the first effluent line into the reactor to remove scale. The oxidized effluent and offgases are then cooled and separated.

Abstract: A two-stage process for purifying wastewater containing organic and adsorbable pollutants includes the steps of first aerating the wastewater in the presence of a powdered adsorbent, such as activated carbon, and biologically active solids in the aeration zone of a primary treatment zone which also includes a quiescent zone. The thus-treated water passes from the aeration zone to the quiescent zone where it is retained a sufficient time for a substantial portion of the suspended solids to settle by gravity. The partially-treated wastewater overflowing from the quiescent zone is introduced into one or more contact zones wherein it is agitated, preferably by aeration, in the presence of a powdered adsorbent, agitation is terminated and the solids are allowed to settle by gravity and, after completion of settling, clarified, substantially solids-free water is withdrawn from each contact zone.

Abstract: Regenerated adsorbent particles, such as activated carbon, are recovered from a wet oxidation-regenerated mixed liquor sludge from a wastewater treatment system by diluting and settling a blowdown slurry from the wet oxidation reactor to obtain a first aqueous phase containing primarily regenerated adsorbent particles and fine ash particles and a first solids phase containing primarily grit particles. The first aqueous phase is combined with a portion of the regenerated adsorbent particle slurry withdrawn from the upper portion of the wet oxidation reactor and, after treatment with a dispersing agent and then an anionic flocculating agent, the resulting mixture is settled to obtain a second aqueous phase containing primarily fine ash particles and a second solids phase containing primarily regenerated adsorbent particles.