CN102774933B - Method for processing high-concentration ammonia nitrogen in rare earth wastewater - Google Patents

Abstract

The invention discloses a method for processing high-concentration ammonia nitrogen in rare earth wastewater. The method comprises the specific steps as follows: firstly, taking 100-mesh to 150-mesh granular active carbon for preparing an electrode with catalytic activity; secondly, filling the rare earth wastewater with the high-concentration ammonia nitrogen into an electrolytic tank; thirdly, adding a NaCl solid and electrolyzing for 3-4h at the voltage of 36-110V; and finally, reducing the concentration of the ammonia nitrogen in the discharged rare earth wastewater to be less than 0.2mg/L. According to the method, the concentration polarization of ion concentration in a surrounding solution is eliminated by the granular active carbon and the electrode with catalytic activity, so thatthe redox reaction is conducted to convert the high-concentration ammonia nitrogen in the rare earth wastewater into nitrogen, and the nitrogen is discharged into the air; the ammonia nitrogen removal rate is more than 99.8%; the voltage is low; the energy consumption is low; and the secondary pollution risk is avoided.

Description

A method for treating high-concentration ammonia nitrogen in rare earth wastewater

technical field

The invention relates to a method for treating high-concentration ammonia nitrogen in rare earth wastewater, belonging to the field of sewage treatment.

Background technique

There are three types of wastewater discharged by pharmaceuticals during the production and smelting of rare earths, mainly acidic wastewater generated by spraying and purifying tail gas of rare earth concentrate roasting, ammonium salt wastewater generated by rare earth carbonate production process, and ammonium salt wastewater generated by rare earth separation. Among them, the rare earth industry produces more than 20 million tons of wastewater every year, with an ammonia nitrogen content of 300-5,000 mg/L, exceeding the national discharge standard by ten to hundreds of times. Ammonia nitrogen pollutants in wastewater is one of the three major wastewater produced in rare earth smelting. Ammonia nitrogen in water quality indicators is an important pollutant that causes water eutrophication and environmental pollution. It can make water lose its self-purification ability and enter the human body. The synthesis of nitroso compounds can induce cancer, and when the ammonia nitrogen content in drinking water is too high, it will cause gastrointestinal disorders and endemic diseases.

In the electrolysis method for treating high-concentration ammonia nitrogen in rare earth wastewater, its advantages lie in the reduction of secondary pollutants, easy operation, remote control, and wide adaptability. This method can effectively remove ammonia nitrogen and other pollutants in wastewater, but It also has the disadvantages of high power consumption and high cost. In order to solve this problem, aiming at the electrolysis method, He Xuwen, Liu Tong et al. proposed in the literature a research on the process of removing high-concentration ammonia-nitrogen wastewater by electrolysis. The molar ratio of ₄ ⁺ to Cl ^- is 1:4, the concentration of Cl ^- increases the number of plates in the electrolysis process to increase the removal rate of ammonia nitrogen, the removal effect of ammonia nitrogen is high, and the power consumption and cost are reduced, but the research Only for pesticide wastewater, etc., the removal effect of high-concentration ammonia nitrogen in rare earth wastewater is still not ideal, and the current intensity of 7-9A still leads to large power consumption, which will inevitably bring expensive treatment costs. For the electrolytic removal of high-concentration ammonia-nitrogen in rare earth wastewater, the literature that can simultaneously achieve low power consumption, low cost, and avoid the risk of secondary pollution has not been reported, nor has it been protected in patents.

Contents of the invention

In order to seek a method for electrolytic removal of high-concentration ammonia-nitrogen in rare-earth wastewater that can simultaneously achieve low power consumption, low cost, and avoid the risk of secondary pollution, the present invention provides a method for treating high-concentration ammonia-nitrogen in rare-earth wastewater. The catalytically active electrode eliminates the concentration polarization of the ion concentration in the surrounding solution, thereby generating a redox reaction to convert the high concentration of ammonia nitrogen in the rare earth wastewater into nitrogen and discharge it into the air. The problem of high energy consumption and high energy consumption avoids the risk of secondary pollution.

In order to achieve the above object, the concrete technical scheme that the present invention takes is:

(1) Take 100-150 mesh granular activated carbon, soak in 0.5M HCl solution for 2-3 hours, rinse 3 times with deionized water under the action of ultrasonic waves, soak in 2M NaOH solution for 3-4 hours, and then use deionized water Rinse 3 times with water under the action of ultrasonic waves, dry naturally, and dry at 105°C for 2 to 3 hours;

(2) Immerse the dried granular activated carbon in the mixed solution of 2.5M Cu(NO ₃ ) ₂ and 1.0M Ni(NO ₃ ) ₂ for 5-6 hours, dry it naturally, and dry it at 105°C 2 to 3 hours;

(3) the granular activated carbon after the above-mentioned treatment is packed into the hollow cylinder microporous iron shell, as the electrolysis electrode;

(4) Pass high-concentration ammonia-nitrogen rare-earth wastewater into an electrolytic cell, add 0.1-0.5% NaCl solid in a mass ratio, and electrolyze at a voltage of 36-110V for 3-4 hours.

Significant advantage of the present invention is:

(1) The electrode with catalytic activity not only has the effect of gaining and losing electrons, but also can eliminate the concentration polarization of the ion concentration in the surrounding solution;

(2) Convert high-concentration ammonia-nitrogen in rare earth wastewater into nitrogen and discharge it into the air through oxidation-reduction reaction, which has the advantages of low voltage and low energy consumption, realizes the goal of energy saving, and avoids the risk of secondary pollution.

specific implementation plan

First, take 100-150 mesh granular activated carbon, soak it in 0.5M HCl solution for 2-3 hours, wash it with deionized water under the action of ultrasonic waves for 3 times, put it into 2M NaOH solution for 3-4 hours, and then use deionized water in ultrasonic wave. Rinse 3 times under the action of water, dry naturally, and dry at 105°C for 2 to 3 hours; then soak the dried granular activated carbon in 2.5M Cu(NO ₃ ) ₂ , 1.0M Ni(NO ₃ ) ₂ in the mixed solution for 5 to 6 hours, dry naturally, and dry at a temperature of 105° C. for 2 to 3 hours; then put the above-mentioned treated granular activated carbon into a hollow cylindrical microporous iron shell as an electrolytic electrode; finally Pass high-concentration ammonia-nitrogen rare earth wastewater into an electrolytic cell, add 0.1-0.5% NaCl solid in a mass ratio, perform electrolysis at a voltage of 36-110V for 3-4 hours, and measure the ammonia nitrogen concentration in the electrolyzed rare-earth wastewater.

Example 1:

First take 105 mesh granular activated carbon, soak in 0.5M HCl solution for 2 hours, rinse 3 times with deionized water under the action of ultrasonic waves, soak in 2M NaOH solution for 4 hours, and rinse 3 times with deionized water under the action of ultrasonic waves , dry naturally, and dry at a temperature of 105 ° C for 2 hours; then immerse the dried granular activated carbon in 2.5M Cu(NO ₃ ) ₂ , 1.0M Ni(NO ₃ ) ₂ mixed solution for 5 hours, Dry naturally, and dry at a temperature of 105°C for 2 hours; then put the above-mentioned treated granular activated carbon into a hollow cylindrical microporous iron shell as an electrolysis electrode; finally pass the rare earth wastewater with an ammonia nitrogen concentration of 2500mg/L into the In the electrolytic cell, the mass ratio of 0.1% NaCl solid was added, and after electrolysis at 40V for 3 hours, the ammonia nitrogen concentration in the rare earth wastewater was measured to drop to 0.1mg/L, the COD concentration dropped from 2000mg/L to 30mg/L, and the removal rate was as high as 99.9%.

Example 2:

First take 150-mesh granular activated carbon, soak in 0.5M HCl solution for 3 hours, rinse 3 times with deionized water under the action of ultrasonic waves, soak in 2M NaOH solution for 3 hours, and rinse 3 times with deionized water under the action of ultrasonic waves , dry naturally, and dry at a temperature of 105 ° C for 3 hours; then immerse the dried granular activated carbon in 2.5M Cu(NO ₃ ) ₂ , 1.0M Ni(N0 ₃ ) ₂ mixed solution for 6 hours, Dry naturally, and dry at a temperature of 105°C for 3 hours; then put the above-mentioned treated granular activated carbon into a hollow cylindrical microporous iron shell as an electrolysis electrode; finally pass the rare earth wastewater with an ammonia nitrogen concentration of 5000mg/L into the In the electrolytic cell, 0.5% NaCl solid was added in a mass ratio, and after electrolysis at 110V for 4 hours, the ammonia nitrogen concentration in the rare earth wastewater was measured to drop to 0.2mg/L, and the COD concentration dropped from 3000mg/L to 60mg/L, and the removal rate was as high as 99.8%.

Example 3:

First take 125 mesh granular activated carbon, soak in 0.5M HCl solution for 2 hours, rinse 3 times with deionized water under the action of ultrasonic waves, soak in 2M NaOH solution for 4 hours, and rinse 3 times with deionized water under the action of ultrasonic waves , dry naturally, and dry at a temperature of 105°C for 3 hours; then immerse the dried granular activated carbon in 2.5M Cu(NO ₃ ) ₂ and 1.0M Ni(NO ₃ ) ₂ mixed solution for 5 hours, Dry naturally, and dry at a temperature of 105°C for 2 hours; then put the above-mentioned treated granular activated carbon into a hollow cylindrical microporous iron shell as an electrolysis electrode; finally pass the rare earth wastewater with an ammonia nitrogen concentration of 3500mg/L into the In the electrolytic cell, the mass ratio of 0.3% NaCl solid was added, and after electrolysis at 80V for 3 hours, the ammonia nitrogen concentration in the rare earth wastewater was measured to drop to 0.1mg/L, and the COD concentration dropped from 2500mg/L to 50mg/L, and the removal rate was as high as 99.8%.

Claims (1)

1. handle RE waste water middle and high concentration ammonia nitrogen method for one kind, it is characterized in that:

(1) gets 100～150 order granulated active carbons, in 0.5MHCl solution, soaked 2～3 hours, wash 3 times under action of ultrasonic waves with deionized water, putting into 2MNaOH solution soaked 3～4 hours, wash 3 times under action of ultrasonic waves with deionized water again, naturally dry, be 105 ℃ in temperature and dried 2～3 hours down;

(2) the Cu (NO of the immersion of the granulated active carbon after oven dry 2.5M ₃) ₂, 1.0M Ni (NO ₃) ₂In the mixing solutions 5～6 hours, dry naturally, be 105 ℃ of oven dry 2～3 hours down in temperature;

(3) the hollow cylinder micropore iron-clad of packing into of the grain active carbon after the above-mentioned processing, as electrolysis electrode;

(4) ammonia nitrogen in high density rare earth waste water is fed electrolyzer, adding mass ratio is 0.1～0.5%NaCl solid, and electrolysis is 3～4 hours under 36～110V voltage, gets final product.