Process for dewatering sludges

摘要

A process for dewatering sludges, which comprises performing a first stage agitation of the sludge to be dewatered during addition of a first high molecular weight flocculant developing in an aqueous solution an electric charge in polarity opposite to that of the sludge to effect neutralization of the electric charge of the sludge, conducting subsequently a second stage agitation of the sludge during a further addition of a second high molecular weight flocculant developing in an aqueous solution an electric charge in polarity opposite to that of said first flocculant to cause flocculation of the sludge and subjecting the so flocculated sludge to a dewatering operation, wherein a flocculant composed of a natural high molecular organic compound or a derivative thereof is used for at least one of said first and second flocculants with simultaneous employment of high power agitation for said first stage agitation, which process obtain a dewatered cake having low moisture content with efficient dewatering of the sludge.