SU1583362A1 - Method and apparatus for electrochemical treatment of waste water - Google Patents

Abstract

The invention relates to a process for the electrochemical treatment of wastewater and allows for an increase in the degree of purification and reduction of energy consumption. The goal is achieved by the fact that the waste water is treated in an electrolytic cell equipped with a soluble anode and a rotating cathode at a current density of 10,000-150000 A / m 2. In this case, the process is carried out by an additional duct 1 / 3-1 / 2 of the purified water through porous an abrasive cathode with a linear flow rate of the treated water in the interelectrode space of 1-5 m / s with a cathode rotational speed of 100-500 rpm and an interelectrode distance of 100-250 µm. A composite material containing a mixture of insulating particles and a conductive metal or graphite binder with a volume porosity of 30-50% is used as the cathode, and compressed metal scrap from steel, aluminum or their mixture is used as a soluble anode. The method is carried out in a device comprising a housing equipped with water inlet and outlet nozzles, with an anode placed in it and a rotating cathode, made in the form of a disk, mounted on the same axis, along which a cylindrical channel is connected in the electrodes, which communicates with the input nozzles. The cathode is located above the anode and has a lid sealed to the cathode to form a cavity under the top of the cathode. On the lid in the channel, there is a windshield that can move in a vertical direction and a dielectric sleeve, the upper end of which is installed at the same height as the top of the cathode, and the lower end below the upper edge of the anode. Holes are made in the side walls of the sleeve, connecting the interelectrode space with the channel. 2 sec. and 1 z. p. f-ly, 1 tab., 1 ill.

Description

The invention relates to a process for the electrochemical treatment of wastewater from contamination, mainly electroplating.

The aim of the invention is to increase the degree of purification and reduce energy consumption.

The drawing schematically shows a device that implements the proposed method.

The device comprises a housing 1, supply pipes 2 of the source water and drain 3 of purified water, an anode 4, with a cylindrical channel 5, a rotating cathode 6, a cover 7 forming a cavity 8, a fairing 9, a sleeve 10 with holes And, a pressure controller 12.

The device works as follows.

Purified water is supplied through the nozzle 2, the cylindrical channel 5 and is distributed through the guide holes 13 into the interelectrode space formed by the anode 4 and cathode 6, as well as through the gaps formed by the sleeve 10 and the cone-shaped fairing 9 into the cavity between the lid 7 and the upper part of the cathode 6, from where, under the action of overpressure, passes through the porous cathode 6, entering the interelectrode space, and is discharged into the housing 1, from where it is removed from the device through the outlet 3. The cover 7 with the cathode 6 is rotated. With the help of the pressure regulator 12 rotating on the thread relative to the cover 7, a predetermined gap between it and the sleeve 10 is set to adjust the ratio of the fluid flow through the interelectrode space and the porous cathode 6.

The sleeve 8 of the flow distributor is made of insulating wear-resistant material such as Teflon, the cover 7, and also the pressure regulator 12 metal.

Example. To obtain a flow-through volume-porous abrasive cathode, an abrasive powder with a grain size, µm: 160,200 (average 180); 200-250 (average 225); 500-600. (An average of 550); 630-800 (average 715), pressed and sintered on a ceramic bond in the form of discs with a diameter of 150 mm, a thickness of 15 mm and an axial bore with a diameter of 20 mm Porosity is provided in the range of 40-60% by the introduction of indierent salts.

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of type (Ш1, () SOe of predetermined dispersion, which are removed during sintering). Volumetric metallization of the disks to ensure their conductivity is carried out by chemical nickel plating with a prior application of the catalytically active layer by the known method of borohydride activation with a solution of nickel salts or by sensitization in hydrochloric acid tin chloride and activation in a solution of palladium chloride, followed by coating in the flow conditions of the composition, g / l: NiCI 6H20 110; triethenolamine 60; 60; KOH 110, hypopho sodium sfit 80, 11-12 pH, temperature 25-30 C. The thickness of the nickel coating 35-20 microns. At this disk porosity cathode is reduced by 10% from the original and is 30- 50%.

Then, using a diamond cutter, the flatness of the disc is refined, in which abrasive grains are exposed simultaneously on its treated plane.

In a device containing a flow-through-porous cathode made of composite abrasive material thus formed, wastewater with a pH of 6.5 is fed, the concentration of Cr (VI) ions is 100 m / l and the surfactant (sulfanol-3) is 50 m / l. Billet of pressed alloyed steel chips serves as the anode. The cathode is rotated by means of an electric drive with a speed of 30-500 rpm.

At the same time, tests are carried out on a known device, including a rotating cathode with three abrasive-insulating inserts between the cathode and the anode, with an inter-electrode distance of 1 mm.

In all cases, the water flow rate is 500 l / g.

Preliminary studies have established the dependence of the interelectrode distance formed during the formation of cathodes by the proposed method on the grain size of the abrasive powder, which is proportional, with an average grain size of 80 microns of 80 microns, with a grain size of 225 microns - 100 microns, with granular 1583362

about 550 microns - 250 microns, with a grain size of 750 microns - 350 microns.

The test results are given in the tables.

As can be seen from the data presented in the table, the removal of surfactants by the proposed method is within 97-99%, while under the conditions of the known method it does not exceed 87%. Energy consumption in comparison with the known method is reduced by 2.2-4.0 times.

As the interelectrode distance increases (more than 250 µm), power consumption increases and surfactant cleaning efficiency decreases. When the interelectrode distance decreases (less than 100 µm), the process efficiency also decreases due to an increase in hydraulic resistance, deterioration of mass transfer and difficulty in withdrawing reaction products from the interelectrode zone. At a current density of less than 10,000 A / ma, the current output does not increase. (more than 15000 A / m2) dramatically increases the consumption of electricity for cleaning. The flow rate up to 1 m / s, as well as the cathode rotation speed of less than 100 rpm, leads to a decrease in the efficiency of the cleaning process, which is associated with insufficient removal of reaction products from the interelectrode zone due to insufficient mass transfer. Exceeding this flow rate (more than 5 m / s), as well as the cathode rotation speed of more than 500 rpm, reduces cleaning of the surfactant and current efficiency.

The cathode porosity of more than 50% also reduces the efficiency of the cleaning process and its mechanical strength. With a decrease in porosity (less than 30%), the cleaning process also deteriorates due to a decrease in the fraction of electrochemically recoverable substances directly in the cathode volume.

In all cases, according to the proposed method, a black precipitate is formed, characteristic of oxide phases based on a magnet, a crystalline structure with clearly pronounced ferromagnetic properties.

With increasing duct through the cathode (more than 1/2 part of the total flow) and decreasing (less than 1/3 part), the degree of chromium purification deteriorates.

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Claims (3)

1. A method of electrochemical wastewater treatment, including their treatment in an electrolyzer equipped with a soluble anode and a rotating cathode at a current density of 10,000-15,000 A / m2-, characterized in that, in order to increase the degree of purification and reduce energy consumption, the process is carried out by additional flow of a part of the treated water through a porous abrasive cathode with a linear flow rate of treated water in the interelectrode space of 1-5 m / s at a cathode rotation speed of 100-500 rpm, interelectrode distance of 100-250 microns. 2. A method according to claim 1, characterized in that a composite material comprising a mixture of insulating abrasive particles and a conductive metal or graphite bundle with a volume porosity of 30-50% is used as a porous abrasive cathode, and a compacted metal is used as a soluble anode the scrap of steel, aluminum, or a mixture thereof, and the additional flow of treated water through the porous cathode is 1 / 3-1 / 2 of the total flow of treated water. 3. A device for electrochemical treatment of wastewater, including a housing equipped with nozzles for supplying raw water and discharging purified water, with an anode placed in it and a rotating cathode made in the form of a disk mounted on the same axis, along which a cylindrical channel is made in the electrodes, communicating with the source water supply nozzle, the cathode is located above the anode and has a lid sealed to the cathode to form a cavity above the top of the cathode, and a fairing is installed in the channel on the cell lid , characterized in that, in order to increase the degree of cleaning and reduce energy consumption, a bushing of a dielectric is placed in the channel, the upper end of which is installed at the same height as the top of the cathode, and the lower end is below the upper edge of the anode, (the side walls of the sleeve) connecting interelectrode space with a channel, and the fairing is mounted with the ability to move nor in the vertical direction using the pressure regulator. The proposed srosob 2 3 four five 6 7 AT 9 ten one 12 13 1h 15 16 17 18 19 20 21 /