RU2099290C1 - Method of treating waste waters from petrochemical and petroleum- processing enterprises to remove dissolved phenols and petroleum products - Google Patents

Abstract

FIELD: waste water treatment. SUBSTANCE: waste water is treated by pulse high-voltage discharges and simultaneously is saturated with dispersed air. Then, waste water is subjected to flotation, biological treatment, and sorption on carbon-sand filters. To waste water, prior to be treated by pulse discharges, coagulant reagent can be added. EFFECT: enhanced purification of waste water. 2 cl, 3 dwg , 1 tbl

Description

 The invention relates to water treatment processes and can be used for wastewater treatment of various chemical industries from dissolved organic substances, for example phenols and petroleum products.

 Currently, there are many methods for the destruction of organic impurities contained in the wastewater of chemical industries. One of such methods is the saturation of water with ozone (Orlov V.A. Ozonation of water. M. Stroyizdat, 1984, 89 pp.).

 But the special power equipment used for these purposes does not allow to process large production flows of wastewater, in this case several ozonizers must be used, which becomes economically unprofitable. In addition, ozonation does not allow to destroy all organic impurities, the effect of oxidizing agents is observed only on easily oxidized compounds. Persistent organic compounds are not destroyed by saturation of the medium with oxidizing agents, combined treatment is required.

 To destroy harmful impurities, chlorination of water is used. But the use of this method for wastewater containing dissolved phenols is unacceptable, since toxic carcinogenic substances (for example, chlorophenols) can form during the treatment of this water with chlorine.

 The use of coagulants for cleaning harmful impurities makes it possible to reduce the content of suspended particles: heavy metal ions and other contaminants, but this treatment makes it difficult to clean industrial wastes from dissolved organic substances.

 A known method of wastewater treatment, including their electrical treatment in the presence of an inorganic salt, which is used as ammonium nitrate. The electrical treatment is carried out in electrolyzers with a current density of 0.04 A / cm for 10 minutes (ed. St. USSR N 1089057, C 02 F 1/46, published 04/30/84, Bulletin of inventions N 16).

 The disadvantages of this method are the low productivity of the cleaning process and the high energy consumption for processing.

 A known method of wastewater treatment, including cleaning from mechanical impurities in the sand traps, water sludge in the secondary sumps, flotation, biological treatment and sorption on coal-sand filters, shown in FIG. 1 ("Instructions for the operation of the mechanical cleaning section of wastewater treatment plants A.O. Achinsky Oil Refinery", approved by the chief engineer A.O. "ANPZ" on 05/20/1994, 15 pp.).

 The closest in technical essence and the achieved effect is a method of treating wastewater, including petrochemical and oil refining industries, including treating them with high voltage pulse discharges while supplying air into the interelectrode space through the hollow reactor electrode, while processing with high voltage pulse discharges (IVR) is carried out with a discharge energy from 300 to 2000 J (ed. St. USSR N 389030, class C 02 F 1/48, publ. 25.06.77, B.I. N 23).

 The disadvantage of this method is that processing with these energy parameters does not allow it to be carried out in a continuous production purification process and requires a large number of pulses per one processed volume of water, which is technically difficult to achieve, and a high degree of purification from dissolved phenols and oil products is not achieved . The low cleaning efficiency of this method is due to insufficiently high pulse energies and a one-stage cleaning scheme, as well as without the use of coagulant reagents.

 The aim of the invention is to increase the efficiency of cleaning from dissolved phenols and petroleum products.

This goal is achieved by the fact that in the known method of wastewater treatment, including the processing of pulsed high-voltage discharges with the simultaneous supply of dispersed air through the hollow grounded reactor electrode, discharges with a specific energy of 7-15 kJ / dm ^{3 are used} and then the wastewater is subjected flotation, biological treatment and sorption on coal-sand filters, and to enhance the cleaning effect, a coagulant reagent is pre-dosed into the reactor.

The inventive method has the following distinctive features:
IVR processing is carried out before flotation of wastewater, followed by biological treatment and sorption on coal-sand filters;
treatment of wastewater IVR is carried out in a continuous hydrodynamic mode with a specific pulse energy of 7-15 kJ / dm ³ ;
coagulant reagent is dosed into waste water before its treatment with IVR.

 The essence of the effect of combined treatment with high-voltage pulse discharges on the degree of wastewater treatment from dissolved organic substances is as follows.

 Conducting a combined treatment according to the claimed parameters allows you to effectively conduct wastewater treatment from dissolved phenols and petroleum products. High energies of pulsed discharges in combination with a whole complex of phenomena accompanying an electric discharge in a liquid (electric explosion), such as shock waves of compression and discharges, strong hydroflows, pulses of electromagnetic radiation, cavitation and radiolysis phenomena, contribute to the destruction of intermolecular and interatomic bonds of organic substances dissolved in water . The introduction of dispersed air into the discharge channel significantly enhances the oxidation processes of phenol degradation and prepares wastewater for subsequent flotation and sorption operations. In order to safely conduct the process, dispersed air is fed into the interelectrode space of the reactor through a hollow grounded electrode, and a positive (+) wire from the pulse current generator is connected to the power electrode. When the dispersed air is not supplied to the interelectrode space of the reactor, the efficiency of purification from dissolved organic substances decreases.

 A preliminary dosage of the coagulant reagent into wastewater before it is treated with an IVR promotes better degradation and coagulates the decomposition products with their subsequent purification by flotation and sorption.

 Treatment with high-voltage pulsed discharges in wastewater treatment processes has previously been used for other purposes, in particular, to improve the quality of recycled water by enhancing the coagulating effect of the treatment of IWR (Kustov A.S. Shepelev I.I. Korostovenko V.V. Clarification of particles in placer development Izvestiya VUZov, Gorny Zhurnal, 1988, N 6, pp. 44-52) and for the destruction of colloidal organic impurities (ed. St. USSR N 1228426, registered 05/30/1984, DMP).

 However, these goals have nothing to do with the claimed increase in the efficiency of purification from dissolved phenols and petroleum products.

The claimed combined treatment was not previously used to solve the problem of purification from dissolved organic substances and with such parameters was not used for this purpose: 7-15 kJ / dm ³ with preliminary saturation of dispersed air into the interelectrode space of the working electric explosive reactor, the addition of coagulant and subsequent flotation, biological treatment and sorption on coal-sand filters. As a result of its application, an increase in the efficiency of purification from dissolved organic substances, in particular from phenols and oil products, is achieved.

 Therefore, the claimed technical solution to the problem of wastewater treatment from dissolved phenols and petroleum products meets the criterion of "significant differences" and "novelty."

 Examples of specific performance of the method.

 The inventive method is tested on a laboratory scale. Samples of wastewater from Achinsky Oil Refinery JSC and specially prepared model aqueous solutions containing dissolved phenol and oil products were taken as the object of research. The proposed method of water purification is carried out according to the scheme shown in FIG. 2. Processing with high-voltage pulsed discharges was carried out in a reactor (1 liter) with a mixing device creating a hydrodynamic regime, a specially mounted pulse current generator (GIT) connected to a working explosive reactor was used as a source of explosive loads (Fig. 3). Air was fed into the treatment chamber through a hollow grounded reactor electrode, previously passing it through a porous membrane. Dispersed air created a water-air mixture in the discharge channel of the reactor, which leads to active oxidative processes during the treatment of IVR due to the formation and release of such oxidizing agents as ozone, oxygen, and O. into the aqueous medium.

The pulse current generator used for the treatment of water IVR, had the following parameters:
breakdown voltage 6.0 kV;
1400 microfarad capacitive energy storage unit;
interelectrode distance 0.5-0.8 mm;
the energy of one pulse was varied from 2 to 20 kJ.

After processing the sample with high-voltage pulsed discharges with a specific energy of 5-20 kJ / dm ^3, water was sent to a laboratory flotation machine, where flotation was performed for 5 min. After flotation, the water was purified by sorption on a coal-sand filter. The table presents experimental data on the content of dissolved phenol and oil products after water purification by treatment with an IVR with different specific discharge energies and a purification scheme.

The data obtained indicate the capabilities of the method when it is used for deep purification of wastewater from dissolved organic substances, such as phenols and petroleum products. The effect of purification or destruction of molecules of harmful dissolved organic impurities is manifested with specific processing energies of 7 kJ / dm ³ . The energy of discharges of more than 15 kJ / dm ^{3 is} impractical, since it can lead to destruction of the working electric explosion reactor, while the degree of purification from dissolved organics remains at the same high level, but there is more erosion of the material of the electrodes.

 The application of the proposed method allows to increase the degree of purification from phenols from 66.5% (prototype) to 99.8%, and achieving this degree of purification becomes possible when using this combined treatment.

Claims (2)

1. The method of wastewater treatment of petrochemical and oil refining industries from dissolved phenols and petroleum products by treatment with pulsed high-voltage discharges with the simultaneous supply of dispersed air into the interelectrode space through a hollow grounded reactor electrode, characterized in that the discharges with a specific energy of 7 15 kJ / dm ^{3 are used} , after which the wastewater is subjected to flotation, biological treatment and sorption on coal-sand filters.  2. The method according to p. 1, characterized in that before treatment with discharges into the wastewater, a coagulator reagent is dosed.

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