Liquid purification or separation – Processes – Treatment by living organism
Reexamination Certificate
2005-05-17
2005-05-17
Prince, Fred G. (Department: 1724)
Liquid purification or separation
Processes
Treatment by living organism
C210S605000, C210S609000, C210S613000, C435S262500
Reexamination Certificate
active
06893566
ABSTRACT:
A sewage treatment system is disclosed in which a waste stream is separated into a primary sludge and water effluent, and the primary sludge is anaerobically digested and dewatered to produce a Class A biosolid. The water effluent is aerobically digested and separated to provide a waste activated sludge. The waste activated sludge is heated in a two-stage process with steam injection and indirect steam before it is passed to a hydrothermal process. The pH of the treated waste activated sludge is then increased, and the nitrogen is stripped and recovered as an ammonium salt. A low nitrogen stream with volatile fatty acids and soluble organics is then separated and fed to the aerobic digester. Biogas generated during anaerobic digestion provides energy for heating the waste activated sludge for the hydrothermal process, and reject heat from the hydrothermal process heats the primary sludge for thermophilic anaerobic digestion.
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Prince Fred G.
Speed & Rogers, P.A.
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