Klärschlammaufbereitung

摘要

A process for treating sanitary sewage sludge to achieve increased solids, decreased viscosity, and a reduction of pathogens. The aqueous slurry of sewage sludge having a solids content in the range of about 3 to 35 wt.% is simultaneously conveyed and preheated (3), macerated (6), heated in an heat exchanger (11), hydrothermally treated in a closed vessel (23) under a blanket of nitrogen at about 500 DEG F and a pressure of about 750 psig and above the vapor pressure of water at that temperature, dewatered and cooled in a first multi-step flash evaporation zone (30) where the pressure is dropped in three steps from about 750 psig to about 50 psig and then in a second flash evaporation zone (40) the pressure is dropped to about 25 psig, cooling and condensing the vapor from said first and second flash evaporation zones (50), and removing a dewatered pumpable slurry of sewage sludge product having a solids content in the range of about 5 to 50 wt.% and a reduced amount of pathogens. The sewage sludge product may be used as land-fill, or land applied, or burned in a partial oxidation gasifier, boiler, or incinerator.