METHOD OF RECOVERING PHOSPHORUS FROM SLUDGE OR THE LIKE

• Main Authors: HOTTA HIDEKAZU, SERA YUTAKA
• Format: Patent
• Language: English
• Published: 24.06.2004
• Edition: 7
• Subjects: CHEMISTRY; METALLURGY; TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE

PROBLEM TO BE SOLVED: To provide a method of efficiently recovering phosphorus from a phosphorus-containing sludge of various kinds and also performing the weight reduction and modification of the sludge and the effective utilization of an inorganic flocculant. SOLUTION: Excess sludge or the like formed from a biological treatment process is treated using a wet reaction device while flocculated sludge or the like formed from a flocculation treatment process is treated using a reducing reaction device to respectively elute phosphorus from those sludges and a phosphorus compound is crystallized from the obtained eluate. Those sludges are preferably treated under such a condition that at a temperature of 150-180°C, under a pressure of < 1MPa, for a treatment time of 30-60 min and in an oxygen deficient state to elute phosphorus in the sludges. Preferably, steam is used in order to hold temperature and a preferable reducing agent is a sulfide. The preferable loadings of the reducing agent are 1-3 in a molar ratio with respect to the amount of a metal contained in flocculated sludge. COPYRIGHT: (C)2004,JPO