RU141342U1 - COMPLEX FOR WASTE WATER TREATMENT FROM OIL PRODUCTS - Google Patents

Abstract

The utility model relates to equipment for the treatment of industrial wastewater from oil products and can be used in enterprises of the oil, oil refining, petrochemical and gas processing industries, as well as in related industries. Offered. a complex for the treatment of wastewater from oil products, which includes a two-stage pre-treatment unit using filtration and oil traps, a flotation unit, a biological treatment unit, a membrane biological reactor unit, a post-treatment unit using photochemical liquid treatment using hydrogen peroxide and UV radiation, and at least one carbon filter. As a result of using the inventive complex, it is possible to completely eliminate the presence of petroleum products and other toxic impurities in wastewater from petrochemical and other similar enterprises.

Description

The utility model relates to equipment for the treatment of industrial wastewater from oil products and can be used in enterprises of the oil, oil refining, petrochemical and gas processing industries, as well as in related industries.

The treatment of wastewater from petroleum products in connection with the growth in production, transport and use of petroleum products is of great importance for preserving the environment ecology. Currently, a large number of technological schemes have been developed that provide a fairly effective treatment of effluents [RU 2404133, RU 2344999, RU 2359919, RU 98123544, RU 2092448, RU 93390 ,. Brodach M.M., Shilkin. N.V. Installation of wastewater treatment Living Machine // Plumbing. - 2002. - N6 and others]. The choice of a specific scheme is determined by the characteristics of the treated effluents, their volume, and the parameters specified during their design. However, stricter regulatory requirements for environmental protection in connection with the observed numerous cases of accidental emissions of petroleum products raise the question of improving treatment schemes to include the results of recent scientific advances, which leads to the use of multi-stage cleaning schemes.

Thus, it is known [RU 24193, 2002] a wastewater treatment plant including a horizontal settling tank, a pneumatic flotation unit and a post-treatment filter, in which, to increase the cleaning efficiency, the settling tank and the flotation unit are equipped with thin-layer clarification units with hydrophobic corrugated surfaces of the shelves, and the flotation machine and post-treatment filters contain a combined filter load.

A known installation for the purification of oily wastewater, including their sequential treatment by sludge in a drive-averager, then in a hydrocyclone with the release of oil concentrate and suspended solids concentrates, filtering in a filter loaded with polyurethane foam as a polymer charge, as well as subsequent post-treatment in electrochemical filter by passing water from top to bottom through a mixture of granules of aluminum and iron, silicified calcite and AG-3 coal. The final water purification is carried out in a sorption filter loaded with activated carbon [RU No. 2156740]. The disadvantage of these plants is the insufficiently high effect of wastewater treatment from dissolved hardly oxidizable organic substances.

A known method of wastewater treatment [US 4487697, 1984], which includes the following steps: mechanical removal of impurities, anaerobic treatment, sludge for 2-10 hours with recirculation of part of the sludge for anaerobic treatment, aerobic treatment, sludge with recirculation of part of the sludge to aerobic cleaning up. Moreover, the biocenosis formed at the stage of anaerobic treatment is maintained separately from the biocenosis of aerobic treatment. The cleaning process is based on the ability of microorganisms to use organic and some inorganic substances dissolved in wastewater, for nutrition in the process of life. In this case, there is a process of growth of biomass, which is an integral part of activated sludge. Precipitation (excess activated sludge) is formed in the primary and secondary sedimentation tanks, which should be disposed of or treated in order to reduce pollution of the biosphere.

However, the processing and disposal of these sediments is very difficult due to their large amount, different composition and high humidity. Various technological processes are used for processing and neutralizing sludge, requiring large capital investments and operating costs, in addition, this technology is characterized by a low degree of water purification (95% according to BOD5).

A known method of wastewater treatment [SU 833582, 1981.] including sedimentation, preliminary aeration with excess activated sludge, flotation, biological treatment in aeration tank mixer, separation of activated sludge from water in a secondary sump, biological treatment on a biofilter, mixing purified sewage with reagent and separation of water from activated sludge in the tertiary sump, the return of 1'2 part of the sediment of the tertiary sump to flotation. Excess activated sludge after biological treatment in the aeration tank mixer is fed to the preliminary aeration stage, and the circulating activated sludge after regeneration is returned to the aeration tank.

The disadvantage of this method and the installation used is the low degree of purification (BOD ₅ 7 g O ₂ / m ³ ; COD 48 g O ₂ / m ³ ; suspended solids 6 g / m ³ ), a large amount of waste generated in the process and, as a result , high capital and operating costs for their processing, as well as high energy costs for pumping water with return sludge. In addition, disinfection of purified water is required.

The closest to the proposed device in technical essence and the achieved result is the installation [RU 113263, 2010], which consists of three functional blocks: pre-treatment, flotation, post-treatment and disinfection. The first block serves for the primary purification of water by isolating large fractions from it through sedimentation and filtration. In the flotation unit, water is treated in a hydrodynamic cavitator and mixed with an ozone-air mixture generated from atmospheric air in a UV lamp, the particles of pollutants interact with the added coagulant, their coarsening and removal through ozonoflotation. The tertiary treatment and disinfection unit provides tertiary treatment of water by filtration using, at the final stage, simultaneous treatment with ultrasound and UV radiation.

The disadvantage of this installation is the relatively low efficiency of cleaning from high concentrations of oil in wastewater, high operating costs at the flotation and post-treatment stages.

The problem solved by the authors was the creation of a more efficient and easier to operate integrated installation for wastewater treatment from oil products.

The technical result was achieved by including in a complex installation containing a pre-treatment unit using filtration, a flotation unit and a post-treatment unit using UV radiation, an additional biological treatment unit and a membrane biological reactor, equipping the post-treatment unit with a photochemical liquid treatment unit, and a pre-treatment unit oil traps with scraper mechanisms. In this case, in an optimal embodiment, the flotation unit includes a pressure flotation unit, and the post-treatment unit contains at least one carbon filter.

The equipment of the pre-treatment unit with oil traps with scraper mechanisms allowed already at this stage to separate some of the petroleum products from the liquid, and the pop-up petroleum products are removed using the scraper mechanism. The liquid freed from a part of oil products, as well as suspended substances, oil products and iron, was able to undergo processing in a bioreactor, where the BOD and the remaining oil products are oxidized, without a large loss of activated sludge activity, and the resulting suspension is removed in a membrane bioreactor block where the level of suspended solids falls below the detection limit, i.e. to practical zero. The resulting product is further purified during the photochemical oxidation of organic substances in the presence of an oxidizing agent (hydrogen peroxide, ozone and other similar substances) while irradiating with a UV lamp, as a result of which the concentration of oil products falls below the detection limit, i.e. to practical zero. The carbon filter is used to guarantee the absence of harmful substances in the effluent and its presence is not mandatory. The general installation diagram is shown in figure 1, where the following notation is used: 1 - 1st stage of the mechanical cleaning unit (BMR); 2 - 2nd stage of the mechanical cleaning unit (BMP); 3 - pressure flotation unit (BNF); 4 - biological treatment unit (BWO); 5 - membrane bioreactor (ICBM); 6 - block photochemical oxidation (BFHO); 7 - installation of post-treatment on charcoal filters (BUF).

BMR 1 is an installation that contains a set of mechanical grids interlocked with sand traps and equipped with a mechanical scraper to remove surface contaminants and a screw mechanism for removing sand and other heavy deposits. As a rule, gratings with a small gap (from 1 to 8 mm) are used, however, successive use of gratings with different mesh sizes is possible - first, gratings are 3 ... 8 mm, then gratings are 1 ... 2 mm.

BOP 2 is a series of oil traps and sand traps equipped with a scraper mechanism.

BRF 3 contains pressure flotators where emulsified oil products are removed. In this case, lamella vertical flotators or other similar structures are used.

BWO 4 includes an anoxide zone and an aeration zone. As a rule, aerotanks using nitri-denitrification technology with a nitrate recycle (either separate or combined with activated sludge recycle) are used in the unit, i.e. a biological process with the removal of nutrients is used.

ICBM 5 is an installation containing a series of submersible hollow fiber membrane modules

BFHO 6 is a reactor in which an oxidizing agent (hydrogen peroxide, ozone, etc.) is introduced into water, after which the water is irradiated with high-intensity ultraviolet

BUF 7 provides, if necessary, wastewater treatment in an emergency.

The complex works as follows. Wastewater enters the BMR 1, where the removal of the main mechanical impurities takes place. At the same time, due to the presence of a scraper mechanism, at the first stage of purification, the most easily separated oil products are also removed. Next, the product to be cleaned enters BOP 2, where it passes through successively placed oil traps. The long residence time of the water in the block allows efficient separation of oil products from the liquid, the pop-up oil products are removed using a scraper mechanism.

Next, the liquid product enters the BRF 3, where it is mixed with a flocculant, for example, aluminum sulfate. As a result of passing through the flotation unit purified by water, the content of suspended solids, oil products and iron is reduced. Then the purified water is sent to biological treatment unit 4, where the BOD and some oil products are oxidized, and then to the membrane bioreactor unit (ICBM 5), where the remaining suspended solids are removed and the biomass of bacteria formed during the biological oxidation stage. As a result, the level of suspended solids falls below the detection limit, i.e. to practical zero. At the last stage in BFHO 6, photochemical oxidation of organic substances occurs in the presence of an oxidizing agent (hydrogen peroxide, ozone and other similar substances) while irradiating with a UV lamp, as a result of which their concentration falls below the detection limit, i.e. to practical zero. The objective of the BFHO is to remove the bulk of the oil products that remained in the water after biology in order to facilitate the operation of carbon filters, because since coal filters will use less oil products, coal will last longer

BUF 7 performs backup functions and turns on when necessary to conduct post-treatment in an emergency.

The essence of the claimed technical solution and its industrial applicability are illustrated by the following examples.

Example 1. At a pilot plant NPP "Biotechprogress", designed according to the claimed scheme, with a capacity of 500 liters of water per day, wastewater treatment tests were carried out.

Purified water - mixed industrial rainwater runoff 1 of the sewage system and saline runoff with ELOU was characterized by the following parameters: BOD (full) - 150 mgO / l, suspended matter content - 200 mg / l, oil product content - 750 mg / l, total salt content - 4000 mg / l, chlorides, not more than 1200 mg / l, iron, not more than 1.5 mg / l. During the treatment, the wastewater enters a 2-stage mechanical treatment. During the mechanical cleaning of the first stage, the content of suspended solids decreased to 170 mg / l, the content of petroleum products to 520 mg / l (other parameters did not change significantly). A significant (more than 30%) decrease in the content of petroleum products is due to the fact that, when they were contained in a concentration of the order of hundreds of milligrams per liter, most of them were present in an emulsified state or in the form of a surface film. Thus, oil traps of the 1st stage made it possible to remove most of the free-floating oil products before they enter the 2nd stage of purification. After cleaning at the 2nd stage, the oil content decreased to 120 mg / l.

As a result of the passage of a reagent flotation block being purified by water (coagulant aluminum sulfate at a dose of 50 mg / l on oxide), the content of suspended solids decreased to 6 mg / l, the content of petroleum products to 8 mg / l, BOD (full) to 60 mgO / l In addition, the iron content decreased to 0.3 mg / L. Then the purified water enters the biological treatment unit, where the BOD and some oil products are oxidized, and then to the membrane bioreactor unit (ICBM), where the remaining suspended solids are removed and the biomass of activated sludge (bacteria) formed during the biological oxidation stage. As a result, the level of suspended solids falls below the detection limit, i.e. to practical zero; the oil content is reduced to 2-3 mg / l. A BOD (full) is reduced to a level of less than 5 mgO / L.

At the last stage, photochemical oxidation occurred in the presence of 50 mg / L hydrogen peroxide, with an irradiation intensity of 4 kJ / m3 As a result, it was possible to achieve a decrease in BOD (full) to a level below the detection limit, i.e. to practical zero. At the same time, the concentration of oil products amounted to 0.04 mg / l.

Example 2. The installation described in example 1 was used for water purification of the following composition: BOD - 260 mgO / l; suspended solids - 450 mg / l, petroleum products - 500 mg / l, total salt content - 3200 mg / l, chlorides, not more than 900 mg / l, iron, not more than 1.5 mg / l

In the process of successive stages of treatment, the quality of the purified water changes as follows: After mechanical cleaning of the first stage, the content of suspended solids decreased to 320 mg / l, the content of petroleum products to 350 mg / l. The remaining parameters were not significantly changed. After passing the 2nd stage, the content of petroleum products decreased to 95 mg / l.

After passing through the reagent flotation block being purified with water (coagulant aluminum sulfate at a dose of 80 mg / l on oxide), the content of suspended solids decreased to 8 mg / l, the content of petroleum products to 7 mg / l, BOD (full) to 50 mgO / l ; iron content - up to 0.2 mg / l.

After passing through the biological purification unit of the ICBM membranes, the level of suspended solids fell below the detection limit, i.e. to practical zero. The oil content decreased to 2-3 mg / l; BOD (full) - up to a level no higher than 5 mgO ₂ / L - so

At the stage of photochemical oxidation with the parameters of example 1, almost complete removal of oil products is achieved.

Example 3. In the installation described in example 1 was wastewater treatment, the composition shown in example 1, with the exception of the concentration of petroleum products of 4600 mg / L. (Such a high concentration is explained by the peak discharge of oil products from the ELOU unit.) During the mechanical cleaning of the 1st stage, the concentration of oil products decreased to 1800 mg / l, which is explained by the fact that at high concentrations the oil products are not very prone to emulsification, therefore, they are easily separated in the form films. At the 2nd stage of mechanical cleaning, the content of petroleum products decreased to 250 mg / l.

At the flotation stage with an increased concentration of flocculant to 70 mg / L in alumina, it was possible to reduce the concentration of petroleum products to the level of 7-8 mg / L. The passage of further stages is similar to the results of example 1.

The developed combination of cleaning methods, as shown by the tested tests, is extremely effective in technical and economic terms for the purification of oil-containing effluents, especially refinery effluents.

Claims (3)

1. A complex for wastewater treatment from petroleum products, including a pre-treatment unit using filtration, a flotation unit and a post-treatment unit using UV radiation, characterized in that the pre-treatment unit further comprises oil traps with scraper mechanisms, the installation further comprising a unit biological treatment unit and a membrane biological reactor unit, and the aftertreatment unit contains a photochemical liquid treatment unit. 2. The complex according to claim 1, characterized in that the flotation unit includes a pressure flotation unit. 3. The complex according to claim 1, characterized in that the aftertreatment unit contains at least one carbon filter.

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