Method for reducing the volume of sludges contaminated with metals and wastewater treatment plants enabling this process to be carried out.

摘要

Process comprises (a) eliminating large solid particles to obtain prim. effluent charged with sludge, (b) prim. decantating prim. effluent to obtain prim. sludge and sec. effluent, (c) stabilising and thickening prim. sludge, (d) biological purificn. of sec. effluent, (e) sec. decantating at exit of biological purifier to obtain treated effluent for discharge and sec. sludge, (f) recycling part of sec. sludge to purifier, and (g) stabilising and thickening remainder of sludge to obtain reusable treated sludge with reduced metal content. Liq., rich in metals, from thickening of prim. sludge, and part of microorganism rich sec. sludge are transferred to a reactor such that metals are fixed onto surface of microorganisms. Clarified effluent is transferred to biological purifier. Sludge from reactor is stabilised and thickened to obtain sludge with high metal content. USE/ADVANTAGE - Effluent treatment (claimed). High proportion of low metal content sludge produced. 80-90% reusable sludge and 10-20% non usable sludge (claimed).