A method for recovering phosphorus and removing heavy metals from sludge incineration ash

Abstract

The invention relates to a method for recovering phosphorus and removing heavy metals from sludge separate incineration ash residues. The method comprises the following steps: taking sludge incineration ash residues from a sludge separate incineration plant; dissolving heavy metals and phosphorus-containing compounds in the sludge incineration ash residues into a solution by adopting a sulfuric acid dissolution method; performing solid-liquid separation on the mixed solution in a centrifugal separator, wherein residues after separation can be treated as general wastes; adding NaOH into supernatant to adjust the pH value to be 8-10; adding Na2S to form deposits with the heavy metals in the supernatant; performing centrifugal separation to achieve removal of the heavy metals; adding Ca(OH)2 into the supernatant after separation to adjust the pH value to be 10-12, wherein Ca<2+> and PO4<3-> in the solution form a calcium phosphate deposit; and performing centrifugal separation to obtain high-quality calcium phosphate, and then achieving an aim of recovering phosphorus in the solution. The method provided by the invention abandons a conventional method for extracting phosphorus from residual sludge, provides a new way of extracting phosphorus from the sludge separate incineration ash residues, and has the advantages of being high in phosphorus recovery efficiency, small in treatment scale, capable of removing heavy metals, and high in calcium phosphate quality.

Description

technical field [0001] The invention relates to a method for recovering phosphorus and removing heavy metals from sludge incineration ash and slag, belonging to the field of sludge incineration ash resource utilization and the field of sludge incineration ash safe disposal. Background technique [0002] Phosphorus is one of the essential elements for the survival of all living things and plays an important role in cell structure and cell function. With the development of industry and agriculture, human demand for phosphate rock is increasing, and phosphorus is a one-way flow element in the biosphere, which further aggravates the contradiction between demand and supply. [0003] Urban sewage contains a large amount of phosphorus. The current biological phosphorus removal process uses the principle of phosphorus absorption / release of phosphorus accumulating bacteria to remove phosphorus by discharging excess sludge. Most of the phosphorus in the sewage goes into the excess sl...

AI Technical Summary

Problems solved by technology

[0005] Sludge incineration can effectively meet the demand for sludge reduction, and the phosphorus-containing compounds in the ash after incineration are enriched to a large extent, but the heavy metal ions in the sludge cannot be effectively removed, only the heavy metal ions in the sludge The ions are transferred to the sludge incineration ash. If the heavy metal ions in the sludge incineration ash are not properly treated, they may cause secondary pollution to the environment.

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