METHOD OF TREATING DIGESTED SLUDGE

摘要

A method of treating, in wastewater purification, sludge containing organic matter, divalent iron and phosphorus, in which the sludge is treated at 0-100%C with an acid at a pH of 1-5 for dissolution of divalent iron and phosphorus from the sludge, the sludge is supplied with an oxidiser selected from hydrogen peroxide and percompounds, divalent iron being oxidised by Fenton's reaction to trivalent iron, and (i) trivalent iron being precipitated as trivalent iron phosphate, (ii) free radicals with a deodorisation and sanitation effect being formed by Fenton's reaction, the sludge then being dewatered at a pH of at most 7, and the aqueous solution obtained in dewatering being recirculated to the wastewater purification. The method is characterised in that the sludge that is treated is made to contain dissolved iron and phosphorus at a molar ratio Fe:P of above 1:1.