RU2297390C1 - Process of treating waste waters containing emulsified petroleum products - Google Patents

Abstract

FIELD: waste water treatment.

SUBSTANCE: invention relates to treatment of hard-to-decompose oil-containing waste waters and can find application in manufacturing industry, mechanical engineering, and other industry fields, where stable emulsions of oils, fats, and petroleum products are formed. Waste water is treated by direct electric current having density 50 to 1000 A/m² using insoluble anodes. Anode space is filled with metal oxide powder, wherein metal is selected from group consisting of iron, zinc, cobalt, zirconium, and mixtures thereof, all being taken in amounts corresponding to 0.5 to 10 g powder per 1 cm² anode area.

EFFECT: enhanced treatment efficiency and reduced consumption of sheet iron.

2 cl, 1 tbl, 9 ex

Description

The invention relates to methods for purifying concentrated and difficult to decompose oil-containing emulsions of wastewater and can be used in processing, engineering and other industries where persistent aqueous emulsions of oils, fats or oil products are formed.

There is a method for treating oil-contaminated wastewater in an electrolytic cell with magnetized iron electrodes, the space between which is filled with a solid backfill of magnetic material / USSR Copyright Certificate No. 889625, MKI C02F 1/46, 1981, Wastewater Treatment Method / V.A. Verbin, V. P. Panov, O.V. Petrovsky, V.D. Mukhortova, B.I. No. 46. 12/15/81 /. The main disadvantages of the method: the impossibility of its use for the decomposition of highly concentrated oil-containing water (C> 1000 mg / dm ³ ), the “dissolution” of the anode with the formation of secondary waste products in the form of metal hydroxides, and the need to use a magnetic field, which entails a rise in price and complexity cleaning technology.

A known method of treating wastewater with electric current using electrodes with backfill of crushed magnetic material between them, for example magnetic ore / USSR Author's Certificate No. 176208, MKI C02C 5/12, 1963 /. The disadvantages of this method include the low cleaning efficiency due to the onset of passivation of the electrodes, which leads to a gradual attenuation of the process, as well as the formation of "oily" metal hydroxides that are difficult to recycle.

Closest to the proposed invention is a method of wastewater treatment / patent of the Russian Federation No. RU 2071948 C1, IPC C02F 1/46, 1997 /, which consists in passing the purified water with dust particles of coke previously introduced into it through stationary bilayer or multilayer porous masses iron particles and anodically insoluble particles by connecting the positive pole of the electric current source to the water being purified. The disadvantages of the method are the complexity of the cleaning process, the low efficiency of the method due to the passivation of iron particles due to the formation of iron hydroxides on their surface and, as a result, an increase in hydraulic resistance to the flow of the transmitted fluid.

The objective of the invention is to increase the efficiency of the water purification process without the formation of secondary waste - metal hydroxides contaminated with oil products. The problem is solved by electrochemical treatment of wastewater containing concentrated stable water-in-oil emulsions, such as cutting fluids, with a constant current density of 50 ... 1000 A / m ² using insoluble anodes located in a layer of one of the following oxides metals: iron, zinc, cobalt, zirconium or mixtures thereof (galvanic sludge dried at 300 ° C can be used as a mixture).

In contrast to the known cleaning methods (for example, electrocoagulation), the proposed method uses electrodes made of stainless steel, titanium, or other materials that are practically insoluble under the influence of electric current, which practically eliminates the passivation of the anode and reduces its consumption due to the absence of metal hydroxides on electrode surfaces.

Example 1

800 ml of wastewater - spent coolant grade "Ratak" containing 12500 mg / l of petroleum products is treated for 2 hours at 20 ° C with a constant electric current density of 50 A / m ² using electrodes made of stainless steel and immersed in a layer iron oxide Fe ₂ O ₃ weighing 25 g (Anode area 50 cm ² ). The residual content of oil in wastewater 82 mg / DM ³ .

Examples 2-8 are presented in the table.

Table N example Fill Material The mass of the filling layer, g Anode material, area, cm ² Current density, A / m ² Temperature ° C Processing time, hour Concentration petroleum products, mg / DM ³ before after cleaning The experiments are conducted in a laboratory setup in a reactor with a capacity of 800 cm ³ . Wastewater: spent coolant brand Ratak 2 Iron oxide, Fe ₂ About ₃ fifty stainless steel 50 500 90 one 11200 55 3 Zinc Oxide, ZnO one hundred stainless steel 50 one hundred fifty one 5600 74 Wastewater: waste coolant brand "Ukrinol-1M" four Zinc Oxide, ZnO 125 titanium, 25 200 one hundred 2 13700 45 5 Zirconium oxide, ZrO ₂ fifty stainless steel 50 250 twenty 2 13700 65 6 Cobalt oxide, CoO 60 ORTA, 30 800 60 one 13700 thirty A mixture of oxides Fe ₂ O ₃ , 40% of the mass. 7 ZnO, 30% of the mass. one hundred ORTA, 30 1000 80 one 13700 23 CoO, 30% of the mass. The experiments are carried out on a semi-industrial installation in a reactor with a capacity of 250 dm ³ . Wastewater: waste coolant brand "VELS-1" Electroplating: Fe ₂ About ₃ , 50% of the mass. 8 ZnO, 20% of the mass. 8000 stainless steel, 800 500 80 5 21,400 117 Cr ₂ About ₃ , 15% of the mass. CuO, 10% of the mass. NiO, 5% of the mass.

Example 9

The experiment is carried out in the conditions of example 1 without the use of a filling layer. The concentration of oil after cleaning is 12000 mg / L.

Claims (2)

1. A method of treating wastewater containing emulsified oil products, comprising treating the wastewater with direct electric current using insoluble metal electrodes, wherein the anode space is filled with a solid backfill, characterized in that the backfill is a metal oxide powder selected from the group: iron, zinc , cobalt, zirconium or mixtures thereof, and the anode space is filled with backfill at the rate of 0.5-10 g of powder per 1 cm ^{2 the} area of the anode. 2. The method according to claim 1, characterized in that the wastewater treatment is carried out with a current density of 50-1000 A / m ² .