Patent ID: 7628925
Filing Date: 2009-12-08
Classification: C02F

Abstract:
1. Method of dewatering sludge, comprising addition of a basic agent to sludge having a pH equal to or less than 8, addition to the sludge of at least one cationic polyacrylamide flocculant, by the addition of the above mentioned basic agent, an increase in pH of the sludge to a value less than a pH as from which degradation of said at least one flocculant takes place, flocculation of the sludge, and separation of the flocculated sludge between dewatered sludge and a liquid phase, wherein the addition of said basic agent increases dryness in said dewatered sludge, wherein the above mentioned basic agent is a calcaro-magnesian compound complying with the formula in which x and y are molar fractions 0.45≦x≦0.75, and 0≦y≦1, and in that said sludge has, until after the said separation, said value lower than a pH as from which degradation of said at least one flocculating flocculant takes place.