SU1456375A1 - Method of purifying waste water from phosphates - Google Patents

Abstract

The invention relates to the treatment of industrial wastewater, can be used in the purification of phosphate-containing wastewater from the production of phosphoric acid extraction, phosphate salts and fertilizers and allows you to increase the degree of water purification and sludge flow properties. For carrying out the process, the wastewater is treated with a mixture of phosphogypsum and wastewater sodium-cationite filters (20% suspension) with lime in an amount of 12-50% of the total. After mixing, the remaining lime is introduced into the wastewater. The residual phosphate content in the wastewater is 7-15 mg / l, the filtration resistivity of the precipitate is 18-25 10 ° C / g, 2 table. (L 4i U1 9) DO

Description

The invention relates to the treatment of industrial wastewater and can be used in the purification of phosphate-containing wastewater from the production of extraction phosphoric acid, phosphate salts and fertilizers.

The aim of the invention is to increase the degree of purification and the water properties of the sludge.

Example 1. Phosphogypsum is mixed with sewage from sodium-cation filter to form a 20% suspension and lime, taken in the amount of 15% of the total consumption

The resulting mixture is introduced into 1 liter of waste water containing 695 mg / l of dissolved phosphates, stirred for 5 minutes, and the rest is added3145

the amount of lime. Water outweighed within 5 min.

After 30 minutes of settling, the clarified water is decanted and the residual content of phosphate in it is determined.

The total phosphate content is 7.0 mg / l, the filtration resistivity of the precipitate is 25.8. 10 cm / g.

Phosphogypsum - waste production of phosphoric acid and phosphate fertilizers. The composition of phosphogypsum includes t,%; CaO 35.5; SO, 43.06; PgOz 1.17; 0.16, A1aOz 0.58, SiOg 1.25, ppt 18.28.

Sewage of sodium-cationite filters contain, mEq / l: CaCl {235; MgCl. 26; NaCl 260. The ratio of Ca: Mg 90:10.

In parallel, the method of cleaning is carried out by a known method with the introduction of a mixture of phosphogypsum with all the necessary amount of lime.

Comparative data on wastewater treatment from phosphates proposed and known methods are presented in table. one.

Example 2, Analogously to Example 1, but the dose of the mixture administered in mixture with phosphogypsum is varied from 10 to 60%,

Dependence of the result of wastewater treatment on phosphate proposed

method of the amount of lime shown in Table 2.

As indicated data table. 2, increasing or decreasing the dose of lime in the mixture with respect to the stated parameters (12-50%) leads to an increase in the residual phosphate content and the specific filtration resistance.

From comparative data on wastewater treatment by the proposed and known methods, it follows that the implementation of wastewater treatment according to the proposed method makes it possible to reduce the phosphate content by 1.5-3 times and to improve the water withdrawal properties of the sludge (decrease the specific filtration resistance by 1.5).

Formula of the invention

A method of purifying wastewater from phosphates, including the treatment of a mixture of 5 SUE phosphogypsum and lime, followed by sedimentation and separation of the resulting sludge, characterized in that, in order to improve the degree of purification and water recovery properties of the sludge, the treatment is carried out with a mixture of phosphogypsum with 12-50% of the total lime and wastewater sodium-cationite filters with subsequent injection of the remaining amount of lime.

Table 1

0

Method parameters

The phosphate content in the source water, mg / l

The amount of phosphogypsum, g / l

The indicators according to the method proposed

.

695

695

table 2

Claims (1)

Claim A method of treating wastewater from phosphates, including treating with a mixture of phosphogypsum and lime followed by settling and separating the precipitate, characterized in that, in order to increase the degree of purification and water-repellent properties of the precipitate, the treatment is carried out with a mixture of phosphogypsum with 12-50% of the total amount of lime and wastewater waters of sodium cation exchange filters with the subsequent introduction of the remaining amount of lime. Table 1 Method Parameters Indicators by the method famous proposed The content of phosphates in the source water, mg / l 695 695 The amount of phosphogypsum, g / l 2 2 The dose of lime mixed with sous phosphogypsum suspension,% of the total dose - 12-50 The residual content of phosphates (PO ^), mg / l 22.0 7-15 The specific resistance of the filter cake (h'Yu), cm / g 30.3 18.1-25.4 The total consumption of lime CaO, mg / l 400 400 table 2 The content of lime in the mixture,% of the total dose The amount of phosphogypsum, g / l The residual phosphate content, mg / l Specific filtration resistance of sediment, 10 ^<0 cm / p The total dose of lime on CaO, mg / l 10 2.0 18.0 44,4 400 12 2.0 9.0 25,4 400 fifteen 2.0 7.0 25.8 400 thirty 2.0 8.0 20,4 400 40 2.0 12.0 19.2 400 fifty 2.0 15.0 19.3 400 60 2.0 24.0 34.5 400 - 2.0 22.0 30.3 400