Patent ID: 7166227
Filing Date: 2007-01-23
Classification: C02F,Y10S

Abstract:
1. A method of treating, in wastewater purification, sludge containing organic matter, divalent iron and phosphorus, comprising: treating the sludge so that it contains dissolved iron and phosphorus at a molar ratio Fe:P of above 1:1; treating the sludge at 0–100° C. with an acid, wherein a pH of 1–5 is achieved for dissolution of divalent iron and phosphorus from the sludge; supplying the sludge with an oxidizer or mixture of oxidizers selected from hydrogen peroxide and percompounds, whereby divalent iron is oxidized by Fenton's reaction to trivalent iron; and dewatering the sludge at a pH of at most 7; and recirculating the aqueous solution obtained in dewatering to the wastewater purification.