Liquid purification or separation – Processes – Separating
Patent
1992-04-01
1993-02-23
Dawson, Robert A.
Liquid purification or separation
Processes
Separating
210770, 210806, 210180, 48197A, B01D 3518
Patent
active
051887410
ABSTRACT:
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, mascerated, heated in an heat exchanger, hydrothermally treated in a closed vessel under a blanket of nitrogen at about 500.degree. 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 where the pressure is dropped in three steps from about 750 psig to about 50 psig and then in a second flash evaporation zone the pressure is dropped to about 25 psig, cooling and condensing the vapor from said first and second flash evaporation zones, 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.
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Khan Motasimur R.
Zang Richard B.
Brent Albert
Dawson Robert A.
Fortuna Ana M.
O'Loughlin James J.
Texaco Inc.
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