Patent ID: 6447687
Filing Date: 2002-09-10
Classification: C02F

Abstract:
A sewage sludge treatment process comprisinga) pumping sewage sludge with a sludge pump through a sludge line to a dewatering apparatus b) mixing polymeric flocculant into the sludge at a dosing point in said sludge line and then c) substantially immediately subjecting the sludge to a dewatering process in said dewatering apparatus and thereby forming a cake and reject liquor, wherein 3 to 40% by volume of the reject liquor is recycled into the sludge line at a suction or discharge side of said sludge pump at a dilution point substantially immediately before the dewatering process, in which the amount of polymeric flocculant dosed into the sludge is no more than the optimum dose of that flocculant for that sludge in that process without the recycling of the reject liquor.