WO2010131991A1 - Complex for the sorption purification of polluted water - Google Patents

Abstract

The invention relates to the removal of harmful impurities, including heavy metal ions, petroleum products and organic waste from industrial water, drinking water and wastewater by means of sorption. The complex for the sorption purification of polluted water comprises a chemical treatment container (5), a pump (3a) and a clarification filter (7) which are connected in succession in the direction of the flow of water to be purified by a pipe between the polluted water intake point and a clean water reservoir (9). The chemical treatment container (5) is connected to a galvanic coagulator (1) by a pipe on which the following elements are arranged in succession between the galvanic coagulator (1) and the above-mentioned container (5): a buffer vessel (2) for collecting debris, a second pump (3b) and an ultrasound activation means (4). The chemical treatment container (5) is provided with an additional pipe forming a circulation loop in which a hydrocyclone (6) is situated. The circulation loop has a connection to a section of pipe between the pump (3a) and the clarification filter (7), the hydrocyclone solid phase removal pipe is connected to the chemical treatment container (5), and the hydrocyclone (6) liquid phase discharge pipe is connected by a pipe to the clarification filter (7). The proposed complex for the sorption purification of polluted water makes it possible efficiently to remove excessive heavy metals, petroleum products and other impurities. The purification technology is economically sound as a result of an improvement in the sorption properties of magnetite and the optimization of the processes for separating the sorbent suspension.

Description

 COMPLEX OF SORPTION CLEANING OF POLLUTED WATERS

The invention relates to the field of purification of industrial and waste water from harmful impurities, including heavy metal ions, oil products and organic pollutants by sorption. It is known to use magnetite Fe ₃ O ₄ as a sorbent for removing oil and oil-containing organic pollutants [US 3767571] and oils [JP 53055659] from wastewater, as well as for effective purification of raw water from bacteria [JP 62053785].

One of the technical solutions for the use of magnetite is its use as an active layer of flow filters, for example, such as those specified in [JP 11057735, JP 7232160].

The disadvantages of filters include their use in the main stream of treated water, which leads to instability of cleaning due to the accumulation of precipitation. Another technical solution for the use of magnetite as a sorbent is its subsequent removal of sorbent from the water stream by means of magnetic separation. It is known to use magnetic separation means in the purification of galvanic wastewater from heavy metals adsorbed by magnetite [KR 20020080521]. In a known solution for purifying water from heavy metals [US 2005189294], heavy metals in water are absorbed by magnetite and removed from water by applying a magnetic field.

To improve the quality of wastewater treatment, magnetite with adsorbed substances is precipitated using flocculants and the precipitate formed is magnetically separated [JP 52056758].

The disadvantage of magnetic separation is the possibility of slip of both magnetite as a sorbent and a sorbent with purified water, which leads to the necessity of separating and removing heavy metal hydroxide adsorbed on the surface of the sorbent from the stream of purified water, otherwise heavy metals can again enter the already purified water during the aging process. In some cases, when a fine fraction of magnetite is required for the sorption efficiency, the quality of treatment is determined precisely by the above-mentioned breakthroughs. It is known that for the purification of water from oil products, natural magnetite is pulverized and a sieve with a 200 mesh mesh is used [CN 101234806]. It was possible to achieve the efficiency of oil removal only by 78 percent, which corresponds to a decrease in the value of chemical oxygen consumption (COD) by about 76 percent.

To remove organic contaminants, it is desirable to have particles about 0.05 μm in size [GB 2446104], for this reason magnetic separation is characterized by relatively low performance.

The main economic disadvantage of the above technologies is the significant cost of the preparation of pulverized magnetite. Among the separation means, the centrifugation method has found development. A known installation containing a hydrocyclone designed for continuous clarification of the water flow [RU 2206408] and providing the allocation of solid suspended particles, oil products and oil-containing impurities, as well as dissolved and insoluble gases from the incoming water. The disadvantage of this installation is that the degree of purification is not high enough due to a significant breakthrough of solid particles from water, especially if the solid particles are small fractions with sizes up to 5 microns.

In practice, synthetic magnetite is obtained in galvanic coagulators, which, in turn, have found application in industrial wastewater treatment systems from heavy black ions and non-ferrous metals, including those from iron, zinc, copper, arsenic, chromium, fluorine, organic flotation reagents, oil products, etc.

A galvanocoagulator is known [RU 2006480], in which insoluble magnetite compounds such as clathrates and goethites are formed due to electrochemical processes between the carbon-containing charge and scrap, which efficiently and reliably sorb heavy metal ions from water (the degree of purification reaches 99.9%) and suspended particles (purity 95%).

It is also known that when galvanic coagulation use a galvanic pair formed by an iron anode and a carbon cathode in the presence of an inert material with dielectric properties [RU 2074125].

In the known method for treating industrial wastewater [RU 2161137], the treatment is carried out in an averaging tank, where the precipitate after galvanocoagulation is also sent. The resulting mixture is subjected to magnetoacoustic resonance in the sound frequency range from 3.5 to 16 kHz with a radiation power of 15 ÷ 20 mW from one to three times a day for 50 ÷ 60 minutes. After separation of the liquid and solid phases, the liquid phase is directed to sequential galvanic coagulation in two galvanic coagulators, the galvanic couple in the first galvanic coagulator being formed from coke and iron particles, and in the second from a mixture of coke and aluminum. After galvanic coagulation, the precipitate is sent to the pre-treatment process, and the liquid phase is treated wastewater used in water recycling systems.

The disadvantage of this solution is the insufficiently complete removal of heavy metal ions, the complexity and duration of the process.

A device is known [RU 2318737] for wastewater treatment, characterized by the presence of series-connected pretreatment reactor, primary sump, galvanic coagulator, ferritor reactor, secondary sump and mechanical filter, while the sediment outlet of the primary sump is connected the sediment accumulator and the filter press are connected in series, the output of the galvanocoagulator sediment through the ferritor reactor is connected to the preliminary purification reactor, and air supply lines are connected to the preliminary purification reactor and ferritor reactor. The intensification of the formation of magnetically susceptible ferrites of heavy and non-ferrous metals is carried out in an additional ferritizer reactor.

The disadvantage is that the device does not provide sufficient fermentation of the precipitate, which is finely dispersed, and does not allow to separate it from the treated solution, which makes it insufficiently effective in operation.

Closest to the claimed in its technical essence is a plant for the treatment of industrial wastewater [RU 2130433] (prototype), containing a receiving tank for wastewater, an ejector, a water pump, a galvanic coagulator and a solid phase separation unit, characterized in that it further comprises an ultrasonic generator and an electromagnet, while an ultrasonic generator is installed between the galvanic coagulator and the electromagnet, and an ejector is installed between the receiving tank and the water pump and is connected to the compressed air line and the ballot filled with carbon dioxide, the solid phase separation unit is made in the form of a thin-layer sedimentation tank and a sand filter installed in series.

In other words, this installation consists of a series-connected pipeline between the intake of contaminated water to a clean water tank through the stream of purified water: a water pump; galvanocoagulator; ultrasonic generator; electromagnet; thin-layer sump and sand filter. Contaminated water is provided with carbon dioxide to increase its acidity.

Wastewater treatment after passing through a galvanic coagulator is carried out in an ultrasonic generator with a frequency of 22 ÷ 44 kHz to alkalize the aqueous medium and the subsequent quantitative precipitation of hydroxides of iron and heavy metals. Subsequent treatment of wastewater with a magnetic field with a strength of 150 ÷ 300 Oe provides an increase in the rate of formation of crystalline iron hydroxide nuclei, which makes it possible to increase the degree of purification of wastewater from anions, and an increase in the growth rate of crystals proper allows for subsequent stages of the wastewater treatment process in a thin-layer sump and on a sand filter, it is more efficient to separate the solid phase.

The main disadvantage of the installation is that the treatment of wastewater in the field of a galvanic couple leads to overgrowing of its elements by deposits of contaminated water, i.e. to passivation of the surface of the filler elements forming the galvanic pair.

Another disadvantage is that the cleaning performance is determined by the dynamics of the formation of magnetically susceptible forms of iron in the galvanic coagulator, which, in turn, occurs in the stream of the water being purified.

It follows that the installation of the prototype is not effective enough and for economic reasons.

The technical task is to improve the quality of treatment of industrial and wastewater from harmful impurities by sorption.

The inventive complex is aimed at improving the sorption properties of magnetite produced by a galvanic coagulator, at optimizing the processes of separation of the sorbent and, as a result, at achieving an economically viable technology for purifying contaminated water from heavy metal ions, oil products and other contaminants.

The technical result is achieved by the fact that a complex of sorption treatment of contaminated water is proposed, comprising sequentially interconnected by a pipeline from the intake of contaminated water to a clean water tank by the flow of purified water, a chemical treatment tank, a pump and a clarification filter, while the chemical treatment tank is also connected to the galvanic coagulator a pipeline on which a buffer tank with a scraper trap function, a second pump and ultrasonic activation means are arranged in series from the galvanic coagulator to the indicated capacity, the chemical treatment tank provided with an additional pipeline forming a circulation loop on which the hydrocyclone is placed, while the circulation loop is connected to the pipeline section between the pump and the clarification filter, the branch pipe of the output of the solid phase of the hydrocyclone is connected to the chemical treatment tank, and The outlet of the discharge of the liquid fraction of the hydrocyclone is connected by a pipeline to a clarification filter.

It is advisable that a buffer tank with a scrap trap function and a chemical treatment tank have connections to a compressed air supply line.

The indicated result is also achieved by the fact that the ultrasonic activation means is made in the form of a hollow chamber equipped with inlet and outlet nozzles for the medium to be treated, into which a waveguide is placed, which has an external connection with an electro-acoustic transducer of vibrations coming from an ultrasonic generator, while the waveguide is made in the form rod with a variable cross-section along its length.

It is desirable that a buffer tank with a scrap trap function and a chemical treatment tank have additional return lines located after the respective pumps and equipped with control valves. It is possible that the galvanic coagulator is connected by a pipe to a clean water tank.

The implementation of the claimed complex sorption treatment of contaminated water allows you to optimize the process of removing excessive amounts of heavy metals, petroleum products and other contaminants. In addition, the system provides for an operational change in the cleaning mode due to the regulated use of the circulation circuit with a hydrocyclone on an additional pipeline. So, separation The purified water from the sorbent occurs mainly in the hydrocyclone, the solid phase from which returns to the chemical treatment tank to maximize the use of its sorption ability. Almost pure water from the hydrocyclone enters the clarification filter, and only a part of the aqueous suspension of the sorbent comes from the chemical treatment tank. Thus, the load on the clarification filter is reduced and its service life is increased.

The iron and coke (or copper) iron hydroxide obtained in a galvanic coagulator with electrodes is in a state far from thermodynamic equilibrium and, therefore, has high internal and surface energy, and, therefore, sorption and ion exchange ability.

The ultrasonic activation means located on the pipeline for feeding the pulp to the chemical treatment tank allows you to further develop the sorption surface of magnetite and, thus, significantly increase the productivity of the proposed complex.

The complex is unified for the treatment of contaminated waters, subject to unpredictable changes in quality indicators. The invention is illustrated in FIG. 1 and 2.

In FIG. 1 is a diagram of the equipment of the complex for sorption treatment of contaminated waters, on which: 1 - galvanic coagulator; 2 - buffer tank with scrap trap function; Behind,

Sv, Zs - pumps; 4 - means of ultrasonic activation; 5 - chemical treatment capacity; 6 - hydrocyclone; 7 - clarification filter; 8a and

8c - control valves of return lines; 9 - a reservoir of clean water.

In FIG. 2 is a schematic drawing of ultrasonic activation means 4 in which: 10 is an ultrasonic generator; 11 - electro-acoustic transducer; 12 - waveguide; 13 - hollow chamber; 14 and 15, respectively, the inlet and outlet nozzles for the medium to be treated. The use of the allocated capacity of chemical treatment allows you to quickly adjust the processes of sorption of contaminants on magnetite. To carry out the reaction throughout the entire volume of the tank, compressed air is supplied to its bottom part. On the clarification filter, the sorbent is deposited from the chemical treatment tank, and spalling solid particles are captured from the water coming from the hydrocyclone, the water is cleaned of impurities.

Using a clean water tank allows the consumer to accumulate purified water.

In a galvanic coagulator, which is a cylindrical body loaded with coke (or copper) and iron scrap, and having a supply of clean water, for example from a reservoir of pure water, the formation of hydroxide forms of iron occurs, with stirring, mainly in the form of magnetite.

The use of a buffer tank with a scrap trap function allows, firstly, the water purification process to be carried out regardless of the operability of the galvanic coagulator and, secondly, to prevent leakage of iron scrap unreacted in the galvanic coagulator together with the magnetite suspension. Due to the fact that magnetite compounds such as clathrates and goethites are also insoluble, but have greater buoyancy, compressed air is supplied to the bottom of the buffer tank.

The use of ultrasonic activation means allows to crush the sorbent developed by the galvanocoagulator, i.e. further develop the sorption surface of magnetite. A variable cross-section of the waveguide rod allows you to organize the mixing of each unit volume of the liquid medium as it passes through the zone of exposure to ultrasound. The circulation circuit with a hydrocyclone placed on it allows the separation of the solid phase and purified water to the filtration stage and the sorbent is efficiently used, returning magnetite in a chemical treatment tank, to maximize the use of its sorption ability.

Additional return lines on the buffer tank with the function of scrap trap and chemical treatment tanks, equipped with control valves, allow to optimize the technological processes for the treatment of contaminated water.

The complex works as follows (Fig. 1). From the intake, the contaminated water enters the chemical treatment tank 5, the aqueous suspension of magnetite obtained in the galvanic coagulator 1 also flows through the pipeline, from which the suspension by gravity first enters the buffer tank with the function of scrap trap 2 and then pump Sv is fed into the chemical treatment tank 5, passing through ultrasonic activation means 4. Pollution adsorbed by magnetite in the form of a suspension of the sorbent from the chemical treatment tank 5 by the pump Z are sent to the clarification filter 7. Significantly The remaining part of the sorbent suspension from the pipeline section between the Za pump and the clarification filter 7 is directed to the circulation circuit, on which the hydrocyclone 6 is placed, from the pipe outlet of the solid phase of the hydrocyclone, the sorbent and unreacted magnetite are returned to the chemical treatment tank 5, and water is removed from the discharge pipe of the liquid fraction of the hydrocyclone with break-through solid particles is sent through a pipeline to a clarification filter 7. In the circulation circuit with a hydrocyclone placed on it, the main separation of solid phase and purified from water pollution. The clarification filter 7 that has passed through a mixture of a suspension of the adsorbent from the chemical treatment tank 5 and the liquid fraction from the hydrocyclone 6 is considered purified water and is sent to a clean water tank 9, where it is accumulated for the consumer.

Using additional return lines of the buffer tank with the function of scrap trap 2 and chemical treatment tank 5, equipped with control valves 8v 8a, the technological parameters of the complex are optimized. So, the use of return line buffer tank 2 allows you to dose the suspension of magnetite in the chemical treatment tank 5, and the use of the return line of the chemical treatment tank 5 allows you to increase the contact time of contaminated water with the sorbent. The water necessary for the operation of the galvanic coagulator 1 is supplied through an additional pipeline by the pump 3c from the clean water tank 9.

The ultrasonic activation means (Fig. 2) works as follows. The aqueous magnetite suspension through the inlet pipe 14 enters the hollow chamber 13, into which a waveguide 12 is placed, which is externally connected to the electro-acoustic transducer of vibrations 11 coming from the ultrasonic generator 10. As the aqueous magnetite suspension passes to the outlet pipe 15, it is subjected to ultrasound frequency 24.5 ± 0.1 kHz, which leads to the grinding of magnetite. The grinding process is intensified by the fact that the waveguide 12 is made in the form of a rod with step thickenings along its length, providing mixing of the liquid medium in the zone of ultrasonic exposure.

Below are examples of the use of a complex of sorption treatment of contaminated water, with a capacity of 2 m ³ / h. Examples illustrate, but do not limit the use of the proposed complex

Example 1. As an example, the following are the data of the protocol of laboratory studies of the effluents of the galvanic shop 121 of the aircraft repair plant in the city of Kubinka, Moscow Region. The results of wastewater treatment by the claimed sorption treatment complex are shown in Table 1.

Table 1.

* GOST 9 314-90 “Products for galvanic production and washing schemes”.

Example 2. As an example, the following are the data from the protocol of laboratory studies of the effluents of the washing section of the rolling stock of the Hevskoe depot of the St. Petersburg metro. The results of wastewater treatment by the claimed sorption treatment complex are shown in Table 2. Table 2.

The claimed complex of sorption treatment of contaminated water allows you to effectively remove excessive amounts of heavy metals, petroleum products and other contaminants. Improving the sorption properties of magnetite and optimizing the processes of separation of the suspension of sorbent makes the treatment technology economically viable.

Claims

Claim 1. Complex sorption treatment of contaminated water, containing sequentially interconnected by a pipeline from the intake of contaminated water to the clean water tank 9 for the flow of purified water chemical treatment tank 5, pump Z and clarification filter 7, while the chemical treatment tank 5 is connected to galvanic coagulator 1 also a pipeline on which a buffer tank 2 with a scrap trap function is placed sequentially from the galvanocoagulator 1 to the indicated container 5, the second pump Sv and the ultrasonic means are activated I 4, and the chemical treatment tank 5 is equipped with an additional pipeline forming a circulation loop on which the hydrocyclone 6 is placed, while the circulation loop is connected to the pipeline section between the pump Za and the clarification filter 7, the solid phase outlet pipe of the hydrocyclone 6 is connected to the chemical treatment tank 5, and the discharge pipe of the liquid fraction of the hydrocyclone 6 is connected by a pipeline to the clarification filter 7. 2. The complex according to claim 1, characterized in that the buffer tank 2 with the function of scrap trap and the capacity of the chemical treatment 5 are connected to a compressed air supply line. 3. The complex according to claim 1, characterized in that the ultrasonic activation means 4 is made in the form of a hollow chamber 13, equipped with input 14 and output 15 nozzles for the medium to be processed, into which a waveguide 12 is placed, having an external connection to the electro-acoustic transducer of oscillations 11 coming from an ultrasonic generator 10, while the waveguide 12 is made in the form of a rod with step thickenings along its length. 4. The complex according to claim 1, characterized in that the buffer tank 2 with a scrap trap function and the chemical treatment tank 5 have additional return lines located after the corresponding pumps Sv and Za and equipped with control valves 8c and 8a. 5. The complex according to claim 1, characterized in that the galvanic coagulator 1 is connected by a pipe to a clean water tank 9.