A method for circularly extracting phosphorus from sludge ash

Abstract

The invention discloses a method for circularly extracting phosphorus from sludge ash. In the method, sludge incineration ash is used as a raw material, and sulfuric acid solution is used for extraction once, and then the extract and concentrated sulfuric acid solution are mixed according to the ratio of 28.8:1.2 to 28.4: The volume ratio of 1.6 is mixed and prepared into a new extractant to extract the remaining sludge ash; according to the needs, the sludge ash can be divided into multiple parts for multiple extractions, and the extractant used in the latter extraction is changed from the previous one. After the extraction is completed, the extract is mixed with concentrated sulfuric acid solution. In the present invention, the extract is used as an extractant, which can greatly reduce the discharge of waste liquid, and after cyclic extraction, the extraction rate of phosphorus in sludge ash can exceed 96%, and the concentration of phosphorus in the final extract exceeds 21-23g / L, can effectively solve the technical problems of low phosphorus extraction rate, large consumption of chemicals and large amount of waste liquid in the prior art.

Description

technical field

[0001] The invention belongs to the technical field of resource recovery in sewage treatment plants, and in particular relates to a method for circularly extracting phosphorus from sludge ash. Background technique

[0002] Phosphorus is one of the essential elements for the survival of all living organisms, and plays an important role in cell structure and cell function. With the development of industry and agriculture, the human demand for phosphate rock is increasing day by day, and phosphorus is a one-way flow element in the biosphere, which further intensifies the contradiction between demand and supply.

[0003] Phosphorus recovery from excess sludge generated during municipal sewage treatment has great potential. After the excess sludge is incinerated, sludge ash with a phosphorus content of 5% to 10% is obtained, which is equivalent to the average content of phosphorus in Chinese phosphate rocks, and has the value of increasing phosphorus.

[0004] A...