SU912663A1 - Method for purifying effluents from heavy metal ions - Google Patents

Description

(5) METHOD FOR CLEANING WASTE WATER FROM HEAVY ITS / METALS

I

The invention relates to a process for the treatment of wastewater from heavy metal ions, mainly wastewater from electroplating.

Electrochemical methods of wastewater treatment from heavy metal ions, oil products, mechanical impurities using soluble til electrodes are known.

A disadvantage of the known solutions is increased power consumption.

The closest technical solution to the present invention is a method of electrocoagulation treatment of wastewater containing heavy metal ions (chromium, nickel, zinc, etc.), which consists in treating such waters in a flow electrocoagulant equipped with a package of steel electrodes. Slurry contained in the electrolyzer) :( um metal hydroxide flakes

Mainly iron and heavy metal ions 12 co-precipitated with them,

The disadvantage of this method is that the electrolysis process is accompanied by the passivation of ions, which leads after a certain time to a reduction in the cleaning effect. In order to ensure a constant and complete cleaning effect, it is necessary to periodically increase the voltage on the electrolysis, which is associated with additional costs of electricity. I Special measures taken in practice to prevent passivation (periodic change of electrode polarity,

15 mechanical cleaning or etching of their surface, the introduction of chlorides, etc. into the wastewater, is inefficient and also requires additional costs. In addition, with this method

20 purification forms a difficult separating suspension of metal hydroxides, which requires the use of large and expensive septic tanks 39 and sludge packers, as well as high-performance filters. The purpose of the invention is to reduce the energy consumption of the cleaning process and increase its efficiency by preventing the electrodes from passivating and obtaining easily separating magnetite suspensions. The goal is achieved by conducting an electrochemical wastewater treatment process in an electrolytic cell placed in an alternating current field at a frequency of kHz. . In this case, a more active state of the surface of the electrodes is provided, which intensifies the anodic dissolution of the metal and stabilizes the electrolysis mode. This treatment forms a suspension of crystalline magnetic particles, effectively separating in a magnetic field.

Known - k, 0

0.12 1.5 ny

As follows from the table, in the process of electrolysis without switching on the high-frequency current generator, a decrease in the current value occurs due to an increase in resistance in the electrolyzer with partial passivation of the electrodes. This leads to a gradual decrease in eff 69, 6

Claims (2)

effect of cleaning and exceeding the MPC values of contaminants. To ensure a sufficient cleaning effect, it is necessary to periodically increase the pressure; At the same time, the average consumption of electrolyzer by the electrolyzer is, on average, over 10 hours of operation of the electric example. Sewage water, containing 50 mg / l of hexavalent chromium, and also 10 mg / l of nickel, zinc, and copper ions, having a pH in the range of 4.0-7.0, is passed through an electrolyzer made of heat-resistant material, inside which is a package steel plate electrodes alternately connected to different poles of a DC source. The electrolyzer is placed in the loop of the high-frequency current generator inductor (UHTP). The table shows the characteristics of the electrolysis process over time and the properties of the suspensions formed during the cleaning process according to the proposed and well-known method, Toe. without imposing a floor on HDTV, ceteris paribus. puller 2, Q-3t kWh, per 1 m drains. When cleaning by a known method, a suspension of flaky particles of metal hydroxides, having a greenish color, turning into a rust color characteristic of iron hydroxide is formed. The particles of this suspension are paramagnetic and have a low hydraulic size. During the process of electrolysis with application of an alternating current field with a frequency of bo-kHz with a specific power of 40-80 W / dm (based on the surface of the electrodes inside the circuit), there is practically no change in the current value during electrolysis after 10 hours of operation of the electrolyzer. In this case, the required degree of water purification from heavy metal ions to their MAC values. The average power consumption is 1.9-2, SqW, h per 1 m of wastewater, which is about 1, -5 pa for less than in the well-known method. In the electrolyzer, a black suspension is formed, the solid particles of which correspond (according to x-ray analysis) to the structure of magnetite and exhibit magnetic properties, their hydraulic size is 2.3-2.8 times higher than in the known method. The magnitude of the specific magnetic susceptibility of these particles indicates their ferromagnetic properties and ensures their effective separation in a magnetic field. When decreasing the frequency value of the specific power indicated in the formula limits, the effect of activation of the electrode surface is insufficient. At ma / shh values of specific power, the magnetite formation reaction proceeds at a low rate and the predominant reaction is the oxidation of Fe to Fe with the formation of a suspension of amorphous rusty iron hydroxide. Increasing the frequency causes excessive suspension overheating. Thus, carrying out electrolysis when applying an alternating current field with a frequency of 60-7 kHz leads to stabilization of the electrolysis mode and reduction of energy consumption for its implementation, as well as increasing the efficiency of the cleaning process by preventing passivation of the electrodes and obtaining magnetite suspension. Claims The method of purifying waste water from heavy metal ions by treating them in an electrolytic cell with soluble electrodes, characterized in that, in order to reduce energy costs by preventing the electrodes from being passivated, the treatment is carried out in an electrolytic cell placed in an alternating current field with a frequency of 60-7 kHz .r Sources of information taken into account in the examination 1. E. Apeltsina, Electrochemical methods in the technology of natural and waste waters. ZINIS. M., 1971, p.35 " 2. Promising methods of wastewater treatment in industry. NIINTI. Minsk, 197, p. 26 (prototype).