SU1188105A1 - Method of removing arsenic compounds from waste water - Google Patents

Description

arsenic is 100.2 mg / l and pH = 5.05; it is fed into the anode chamber of the diaphragm electrolyzer, in which the anionite 5 MA-40 membrane is used as a diaphragm with an inert fabric installed close to it from the anode side, for example, tarpaulin. The cathode chamber is filled with a 20% solution of ΝβΟΗ, a constant current source is connected, and at a current density of 1.6 A / dm ^2, and voltage E = 2V conduct electrolysis for 5 min. The treated water is drained and left to stand for 1.5 hours. The clarified water determines the residual arsenic content, which is 0.05 mg / L.

The change in the efficiency of wastewater treatment from arsenic compounds depending on the pH value of the runoff is shown in table. one.

The invention relates to the treatment of wastewater from arsenic compounds and can be used in enterprises of metallurgical, chemical, electronic and other industries.

Industrial effluents containing arsenic compounds are among the most toxic liquids. The concentration of arsenic compounds in wastewater before their discharge into the city sewer should not exceed 0.1 mg / l, in natural waters 0.05 mg / l.

The purpose of the invention is to increase the degree of purification and intensification of the process.

The method is as follows.

Example. Wastewater from pro. 20 arsine production at concentration

Table 1

pH Time back Mouse concentration - Mouse concentration - 2 boots min ka in stock, mg / l ka in purified liquid ΐ A / dm bones, mg / l E, B

1.25 3 100,2 39.2 2 1,6 3.0 3 100,2 0.35 2 1,6 4.05 3 100,2 0.18 2 1,6 5.05 3 100,2 0.12 2 1,6 6.1 3 100,2 0.20 2 1,6 7.2 3 100,2 0.38 2 1,6 9.8 3 100,2 1.27 2 1,6

The effectiveness of purification from the connectiveness of the treatment is shown in arsenic depending on the length of the table. 2.

Table 2 *

Processing time, min Arsenic concentration in stock mg / l The concentration of arsenic in the purified liquid, mg / l RNish liquids Λ 1, A / dm E, B - 2 3 four 5 7 6 2 100,2 0.48 5.05 1,6 2 3 100,2 0.12 5.05 1,6 2 four 100,2 0.15 5.05 1,6 2

Continuation of the table. 2

one .2 -: - G-1 3 four 5 (, 5 100,2 0,042 5.05 1,6 2 6 100,2 0,03 5.05 1,6 2 7 100,2 0.02 5.05 1,6 2 8 100,2 0.02 5.05 1,6 2 10 100,2 0.02 5.05 1,6 2

As can be seen from the above data, 15 the maximum effect of purification from arsenic is achieved at a pH of 4-6 and a processing time of 4-5 minutes.

A further increase in the duration of the process leads to unproductive costs of electricity and metal.

The presence of an inert membrane installed in the anode chamber before the selective one prevents clogging of the last iron hydroxide formed during the anodic dissolution of the metal. This makes it possible to carry out the process of electrochemical treatment at pH values that provide optimal conditions for the formation of hydroxide and the course of the coagulation process. In addition, the life of the selective membrane is increased. s ₅

Comparative data on the effectiveness of purification from arsenic by the known and proposed methods are presented in table. 3.

Table 3

Indicators Way Famous ny Offers gay Concentration arsenic in the outcome- nom stock mg / l 98.6 100,2 The current density at the anode, A / dm ^ · 1,6 1,6

Editor I. Kovalchuk

Compiled by V. Vilinsky Tehred O. Netse

Continuation of the table. 3

Indicators Way Famous ny Offers gay Processing time, min eighteen 5 pH of the source fluid 4.00 4.05 The residual content of arsenic in the purified liquid, mg / l 0.94 0.05

To this it should be noted that after 6 hours of operation of the electrolyzer in the known method, the selective membrane is clogged with metal hydroxide (sludge) and requires replacement.

Thus, the proposed method provides a more intensive and effective disposal of arsenic-containing wastewater compared to lime. in the proposed method, the degree of purification is significantly increased, the time of electric processing is reduced, and the service life of the membrane is increased.

Claims (3)

1. METHOD FOR WASTE WATER CLEANING FROM ARSENIC COMPOUNDS by electrochemical treatment in the anode chamber of an electrolyzer with a diaphragm and a soluble iron anode, characterized in that, in order to increase the degree of purification and intensification of the process, the electrochemical treatment is carried out at pH 4-6 for 4-5 min, and as a diaphragm, a selective anion exchange membrane with an inert tissue adjacent to it from the anode side is used. 2. The method of pop. 1, characterized in that the cathode chamber of the cell is filled with 4-5 n solution of NaOH or KOH. 3. The method of pop. 3, characterized in that a tarp is used as an inert fabric.