Process for recovering regenerated adsorbent particles and separating

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 The first aqueous phase is combined with a portion of the regenerated adsorbent particle slurry withdrawn from the upper portion of the wet oxidation reactor and, after treatment with a dispersing agent and then an anionic flocculating agent, the resulting mixture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. The second solids phase is recycled to the treatment system for reuse and, after treatment with a cationic flocculating agent, the second aqueous phase is settled to obtain a substantially particle-free third aqueous phase and a third solids phase containing primarily fine ash particles. Slurries containing the grit and fine ash particles are combined and dewatered prior to disposal.