RU2841406C1 - Plant for complex treatment of waste and drinking water - Google Patents

Abstract

FIELD: water treatment.

SUBSTANCE: invention relates to purification of waste water and drinking water from suspended particles, ions of contaminants from natural underground and surface water sources, characterized by high content and seasonal fluctuation of content of mineral and organic contaminants in a wide range of concentrations. Installation includes: inlet tank 1 with installed in it vacuum-ejection treatment unit 2, reagent dosing unit 3, electrocoagulation processing unit 4, water degassing tank 5, gravitational clarification unit 6, filtration unit 7, purified water accumulation unit 8. Outlet of inlet tank 1 is hydraulically connected to electrocoagulation treatment unit 4, which includes power supply sources and electrolysis unit 12 with soluble electrodes in the form of rods from aluminium or iron. Output of electrocoagulation treatment unit 4 is hydraulically connected to degassing tank 5, one of the outputs of which is hydraulically connected in series to clarification unit 6, filtration unit 7, purified water accumulation unit 8. Each of the electrodes of the electrolysis cell is connected by an air duct to compressor 14. At one of the outlets of degassing tank 5 there is pump 14, which feeds a portion of the purified water back into electrolysis cell 12.

EFFECT: improved quality of the treated water, longer effective operation of the electrolysis cell.

2 cl, 1 dwg, 1 tbl

Description

Scope of application

The invention relates to the purification of waste water and drinking water from suspended particles, pollutant ions, from natural underground and surface water sources characterized by a high content and seasonal fluctuations in the content of mineral and organic pollutants in a wide range of concentrations.

State of the art

A device for electrocoagulation purification of waste water is known (RU Patent No. 57270, IPC class C02F 1/46, date of publication 10.10.2006), comprising a housing divided by partitions into an electrode chamber with soluble electrodes, a settling chamber and a discharge chamber, which are connected to each other by windows in the partitions, a foam removal tray, a branch pipe for feeding raw water, a branch pipe for draining purified water, and a branch pipe for draining sediment.

A method for electrocoagulation purification of phenol-containing waters is known (RU Patent No. 2198848, IPC class C02F 1/463, date of publication 20.02.2003), in which electrocoagulation is carried out in a diaphragmless electrolyzer under oxygen pressure of 0.5-0.8 MPa at a current density of 5 mA/cm ² . St-3 was used as the electrode material. Phenol oxidation occurs due to adsorption on iron hydroxide and dissolved oxygen.

A device and method for wastewater treatment are known (RU Patent No. 2494976, IPC class C02F 1/463, published on 10.10.2013), having an electrocoagulation reactor and a settling tank for receiving the flow leaving the reactor. The reactor has a reaction tank having an inlet channel and an outlet channel, a consumable anode, a rotating cathode and a non-consumable anode. The first gap between the consumable anode and the cathode constitutes the first water treatment zone. The second gap between the cathode and the non-consumable anode constitutes the second water treatment zone. The water flow route passes from the inlet channel to the first treatment zone, then to the second treatment zone and then to the outlet channel. In the settling tank, the flow leaving the reactor is separated into purified water and contaminated sludge.

A device for wastewater treatment is known (RU Patent No. 212109, IPC class C02F 1/463, published on July 6, 2022), comprising a housing with an inlet pipe, an outlet pipe and a sludge drain pipe, inside which there is a chamber with an installed electrocoagulator, which is a block of electrodes made in the form of plates made of a metal alloy, and an outlet opening through which it communicates with a clarification chamber, in the upper part of which a flow divider with through cells is installed, as well as an outlet chamber with a filtration unit communicating with the clarifier via a pipeline, wherein the electrocoagulator is connected to the inlet pipe, the sludge drain pipe is made in the lower part of the clarification chamber, and the outlet pipe is made in the outlet chamber. The device additionally contains a feed pump installed on the inlet pipe and a vacuum pump installed on the outlet pipe, and the filtration unit is connected to the vacuum pump and is a ceramic membrane unit with a pore size of 0.001-100 μm.

A known method for electrochemical purification of domestic, drinking and industrial water (RU Patent No. 2687416, IPC class C02F 1/463, published on 13.05.2019) includes electrocoagulation with stainless steel electrodes with a pre-galvanically applied coating 0.2 mm thick. Subsequent filtration is carried out on a cascade of sorbents selected from natural or artificial cellulose, white quartzite and quartz sand with a grain of 0.2 mm, a surface-modified encapsulated anion exchanger based on silica gel with a grafted quaternary ammonium group with methyl, ethyl, methylethoxy substituents with pores of 50 nm, and a cation exchanger with carboxyl groups grafted to a silica gel matrix with pores of 40 nm. All operations are carried out in a single electrocoagulation reactor.

An automated device for cleaning industrial wastewater is known (RU Patent No. 2653169, IPC class C02F 1/463, date published 07.05.2018), comprising a series-connected receiving chamber 1 with a reagent dispenser 2 installed above it, a static mixer 3, an electrocoagulator 8 with electrodes and a paddle mixer 9, pH meter sensors 5, a chamber 11 with a high-pressure pump 12, a continuous filter-thickener 13, a receiving tank for wet sediment 15, a press filter 18, heavy metal impurity concentration meters 16, a pump for pumping untreated water 23, a storage tank 24, a pump 25 for feeding water for a repeated cleaning cycle, control valves, microprocessor controllers 17 and 20, an ultrasonic flow meter 26 at the inlet pipeline, reagent feed corrector 38, adder 37, scaling and correcting amplifiers, input flow value sensor 33, flow comparison unit 32, frequency controllers and paddle stirrer mixing speed corrector 41.

A known installation for electrocoagulation purification of drinking and waste water (RU Patent 2758698, IPC class C02F 1/463, 9/04, published date 01.11.2021) contains four-section galvanoinduction and electrocoagulation treatment units with soluble electrodes made of metals of different valence installed in them, a reagent dosing unit, a flotation treatment unit, a suspended layer chamber, a thin-layer settling chamber with thin-layer modules and a power source. An electromagnetic coil with an operating frequency of 25-135 kHz is installed in the common internal space of the four-section galvanoinduction treatment units and the electrocoagulation treatment unit. Four-section galvanoinduction treatment units form two stages with four sections each, and a potential of 0.5-0.9 V is induced in each section of the galvanoinduction treatment unit. The disadvantage of this unit is the absence of a mixing and oxidation unit for the incoming water, as a result of which pollutants are not oxidized for their further removal, the absence of a degassing unit for removing gases produced during electrocoagulation treatment, the design of the electrodes in the form of plates reduces their useful mass, and also worsens the energy efficiency of coagulant production, the use of aluminum hydroxychloride or oxychloride in the unit leads to an increase in the concentration of chlorides in the purified water, which can negatively affect its quality.

A technology for the system-integrated electrocoagulation treatment of drinking water and the modular station "Waterfall" for its implementation are known (RU Patent No. 2591937, IPC class C02F 9/12, date published 20.07.2016), implemented in a modular station containing sequentially located functional modules: a module for preliminary purification and degassing of source water, a module for circulating water conditioning, a module for integrated electrocoagulation treatment of water, a module for cascade clarification and purification of water, a module for fine final purification and disinfection of water, through the continuous implementation of controlled technological processes for removing suspended pollutants, free carbon dioxide, hydrogen sulfide, ammonia, volatile odorous substances from water, saturating water with atmospheric oxygen, conditioning water by means of circulating mechanochemical disaggregation of colloidal and hydrate-associated pollutants with simultaneous dosing of sodium chloride, alkaline or acid reagents, providing optimal values of electrical conductivity and hydrogen index of water, degree of oxidation of pollutants. Then, complex electrocoagulation, electrochemical and electromagnetic treatment of conditioned water is carried out in an electrocoagulator with soluble electrodes made of high-purity aluminum with the implementation of cleaning of the said electrodes, mineral and organic substances converted to an insoluble state are removed in the process of cascade clarification of water with provision of organized movement of purified water first from top to bottom, and then from bottom to top and fine final cleaning by filtration with final disinfection by ultraviolet irradiation.

A known method for electrocoagulation purification of drinking and waste water (RU Patent No. 2751394, IPC class C02F 9/02, 9/12, published on July 13, 2021) includes four-stage galvanoinductive treatment units of the first and second stages, a four-stage electrocoagulation treatment unit, a high-frequency electromagnetic treatment system, a perpendicular field electromagnetic treatment unit, a flotation treatment unit with gas separation, suspended layer chambers for deep sorption treatment, step-by-step thin-layer settling chambers, a filter with a floating polymer load, a power and control unit, a power supply unit for a high-frequency electromagnetic treatment system, and a dosing unit for a correction solution. Water is processed four times in the first stage four-stage galvano-inductive processing unit and four times in the second stage four-stage galvano-inductive processing unit, wherein water is simultaneously processed in an electromagnetic field with a frequency of 25-135 kHz with subsequent processing in electromagnetic fields perpendicular to each other. The disadvantage of the method is an increase in energy costs due to the use of a high-frequency electromagnetic processing system, as well as an increase in the overall dimensions of the installation due to the use of flotation processing, which requires a significant area and a system for collecting sediment by scraping.

A known method for purifying wastewater of various origins (RU Patent No. 2721789, IPC class C02F 9/06, published on 22.05.2020), in which roughly primarily purified wastewater is subjected to vacuum-gravity-ejector treatment with simultaneous reagent supply. The wastewater is then sent to multi-stage primary electrocoagulation treatment with a return circulation ratio for repeated electrical treatment of 6-7:1, flotation treatment, treatment in a suspended layer chamber with a ratio of the chamber height to its area equal to 1.62, primary clarification in a clarification chamber with a labyrinth and vertically installed thin-layer modules. Then the wastewater is fed to secondary clarification in a chamber with two sections and horizontally installed thin-layer modules with a ratio of the amount of downward flow to the upward flow equal to 0.72. Primarily electrically treated and twice clarified wastewater is fed to the second stage of electrocoagulation treatment. Then it is fed to the suspended layer chamber with a height to area ratio of 1.62, thin-layer settling in a chamber with horizontally installed thin-layer modules with a descending to ascending flow ratio of 0.72. Clarified wastewater is fed to a self-cleaning filter with a filter load of foamed polystyrene of fraction No. 4 or No. 5. Then the filtered water is fed to the regulating tank, and the wash water is discharged to the tank for wash water and sediment. The accumulated sediment is discharged from the clarifiers of the first and second stages of electrical treatment and clarification. The sediment and wash water are fed to the sediment compaction tank, and a flocculant solution is also fed there. The compacted sediment is fed to a filter press, and the decanted, settled water is returned for re-purification.

The closest in design is the method and installation for cleaning acidic mine waters (RU Patent No. 2822699, IPC class C02F 1/66, date of publication 11.07.2024), including a series-connected tank for accumulating the initial acidic mine water to be cleaned, inside which an ejection unit is located, while the installation includes a reagent dosing tank with a NaOH reagent, a reagent dosing tank with a NaCl reagent, the outputs of which are hydraulically connected to the ejection unit, while the output of the tank for accumulating the initial acidic mine water to be cleaned is hydraulically connected to the input of series-connected electrolyzers with dissolving electrodes, in one of which the electrodes are made of aluminum, and in the other the soluble electrodes are made of iron, while the output of the electrolyzers is hydraulically connected to a degasser, the output of which is hydraulically connected to the input of the gravity separation and clarification tank with the gravity separation unit located inside it and a clarification unit, and the outlet from the gravity separation and clarification tank is hydraulically connected to the inlet of the complex pressure filter, the outlet of which is hydraulically connected to the inlet of the purified water tank, inside which there is a galvanic softening unit made of a set of metal-galvanic pair plates, for example, copper and aluminum. The disadvantage of the installation is the unification of the water supply line and the circulation line, which in the case of drinking water purification significantly reduces the efficiency of the installation.

Disclosure of the essence of the invention

The technical result of the claimed invention is an improvement in the quality of treated water by increasing the time the treated water is exposed to electric current, as well as increasing the effective operating period of the electrolyzer.

The technical result is ensured due to the fact that the integrated wastewater and drinking water purification plant includes an input tank with a vacuum-ejection treatment unit installed therein, a reagent dosing unit, an electrocoagulation treatment unit, a water degasser tank, a gravity clarification unit, a filtration unit, a purified water accumulation unit with a bactericidal treatment unit installed therein, wherein the output of the input tank is hydraulically connected to the electrocoagulation treatment unit, including power sources and an electrolyzer with soluble electrodes in the form of aluminum or iron rods, wherein, in order to increase the service life of the electrodes of the electrocoagulation treatment unit and to ensure their longer effective operation, each of the electrodes of the electrolyzer is connected by an air duct to a compressor, wherein the output of the electrocoagulation treatment unit is hydraulically connected to the degasser tank, wherein, in order to reduce current loads during water treatment, as well as to increase the time the treated water is exposed to electric current in order to improve the quality of water purification, for the implementation of circulation of water in the electrolyzer, at one of the outlets of the degasser tank a pump is installed, which feeds part of the purified water back to the electrolyzer, while the other outlet of the degasser tank is hydraulically connected to the clarification unit, while inside the tank of the clarification unit a flow laminator is installed, which allows to reduce the turbulence of the incoming flow of the purified liquid, while the outlet of the clarification unit is hydraulically connected to the filtration unit, which is hydraulically connected to the purified water unit.

Brief description of the drawings

Fig. 1 shows a diagram of a complex wastewater and drinking water treatment plant.

Implementation of the invention

The complex purification plant for waste and drinking water includes an input tank 1 for accumulating purified water with a vacuum-ejection treatment unit 2 installed in it, a reagent dosing unit 3, an electrocoagulation treatment unit 4, a water degasser tank 5, a gravity clarification unit 6, a filtration unit 7, a purified water accumulation unit 8 with a bactericidal treatment unit 9 installed in it.

The water supplied for purification is directed to the input tank 1, from where the circulation pump 10 supplies the water to the system of ejectors 11 of the vacuum-ejection processing unit 2, installed inside the input tank 1, to which the required amount of reagent is added from the reagent dosing unit 3.

The outlet of the input reservoir 1 is hydraulically connected to the electrocoagulation treatment unit 4, which includes power sources and an electrolyzer 12 with soluble electrodes in the form of aluminum or iron rods. In order to increase the service life of the electrodes of the electrocoagulation treatment unit 4 and to ensure their longer effective operation, each of them is connected by an air duct to a compressor 13, which ensures the purging of the electrodes that become clogged during the electrochemical treatment of water.

The outlet of the electrocoagulation treatment unit 4 is hydraulically connected to the degasser tank 5, which has a system of pipelines and exhausts for gas removal (not shown in the figure), located above the level of other units for more effective gas removal. In order to reduce current loads during water treatment, as well as to increase the time the treated water is exposed to electric current in order to improve the quality of water purification, to circulate water in the electrolyzer 12, a pump 14 is installed at one of the outlets of the degasser tank 5, feeding part of the purified water back to the electrolyzer 12.

The other outlet of the degasser tank 5 is hydraulically connected to the clarification unit 6, made in the form of a container with a calculated cross-sectional area depending on the required productivity, the flow rate in which ensures the liquid level rises at a rate of 0.5-2 cm/min. At the inlet, inside the container of the clarification unit 6, a flow laminator 15 is installed in the form of a perforated section of a pipe, allowing to reduce the turbulence of the incoming flow of the liquid being purified.

The outlet of the clarification unit 6 is hydraulically connected to the filtration unit 7, which includes a polystyrene filter and a complex pressure filter 16.

The outlet of the filtration unit 7 is hydraulically connected to the purified water unit 8, in which bactericidal treatment of the purified water is carried out using the bactericidal treatment unit 9.

The drains of the input tank 1, the electrocoagulation treatment unit 4, the degasser tank 5, the clarification unit 6, the filtration unit 7, the purified water accumulation unit 8, are hydraulically connected to the drainage line. The hydraulic communication lines include the necessary pumps, meters and shut-off valves.

The integrated wastewater and drinking water treatment plant operates as follows:

A reagent - NaOH - is introduced into the purified waste or drinking water received in the input tank 1 at a dosage of about 0.1-2 kg/ ^m3 to bring the mixture to a pH of 7-9, from where the water is fed by a circulation pump 10 to the system of ejectors 11 of the vacuum-ejection treatment unit 2, simultaneously aerating to separate and remove volatile substances from the source water and to oxidize the under-oxidized substances in it.

The purified water that has undergone vacuum-ejection treatment is sent to the electrocoagulation treatment unit 4, which includes an electrolyzer 12 with soluble electrodes made of iron or aluminum for undergoing electrical treatment, leading to structural changes in the treated water, the formation of a suspension of coagulant and flocculant aluminum hydroxide or iron hydroxide, obtained by dissolving the electrodes.

The electrolyzer electrodes 12 are purged in order to increase their effective service life by supplying air from compressor 13 in the event of a short-term (0.1-1 hour) increase in network voltage by more than 3-5% due to electrode passivation. The purified water processed in electrocoagulation processing unit 4 is sent sequentially to water degasser tank 5, from which, through a system of pipelines and exhausts (not shown in the figure), gas accumulated during ejection and electrocoagulation processing is removed, due to the location of degasser tank 5 above the level of the remaining system tanks for more effective gas removal.

Through one of the outlets of the degasser tank 5, part of the water is sent back to the electrolyzer 12 by pump 14 in order to reduce current loads during water treatment, as well as to increase the time the treated water is exposed to electric current. The remaining purified water is sent to the clarification unit 6 through the other outlet of the degasser tank 5.

In the clarification block 6, due to the flow laminizer 15, a laminar rise of water in the tank and sedimentation of the coagulant and flocculant suspension are carried out, regulating the flow rate so that it ensures the rise of the liquid level at a rate of 0.5-2 cm/min. Clarified water flows by gravity from the upper part of the clarification block 6 to the filtration block 7.

In filtration block 7, the purified water is initially passed through a polystyrene filter, then through a complex filter 16 filled with media that provide additional purification of water from cationites and anionites.

The water filtered in the filtration block 7 is sent to the purified water block 8, where bactericidal treatment of the purified water is carried out in the bactericidal treatment block 9.

The drains of the input tank 1, the electrocoagulation treatment unit 4, the degasser tank 5, the clarification unit 6, the filtration unit 7, the purified water accumulation unit 8, are hydraulically connected to the drainage line. The hydraulic communication lines include the necessary pumps, meters and shut-off valves.

The results of wastewater treatment at the presented installation are shown in Table 1.

Table 1

The characteristic being determined Units of measurement Measurement result SanPiN 2.1.4.1074-01. Drinking water. Hygienic requirements for the quality of water in centralized drinking water supply systems. Quality control) Before water purification After water purification pH pH units 2.9 9 6-9 Rigidity mmol/dm³ 20.79 6.8 7.0 Sulfates (SO4) mg/l 300 250 500 Chloride ion CI mg/l 9.35 12.7 300 Calcium Ca mg/l 233 111.2 - Magnesium Mg mg/l 72.8 2.2 - Iron (Fe, total) mg/l 15 0,1 0.3 Manganese mg/l 10.4 0.065 0,1 Beryllium (Be, total) mg/l 0.0142 0.00013 0.0002 Cobalt Co mg/l 0.061 0.0063 0,1 Lithium Li mg/l 0.28 0.015 0.03 Nickel Ni mg/l 0.184 0.005 0.1

Thus, after treatment, the hardness of wastewater decreased by more than 3 times, the iron content decreased by more than 100 times, manganese - by 160 times, beryllium - by more than 100 times, cobalt - by 10 times, lithium - by 15 times, nickel - by 36 times, satisfying the requirements for drinking water quality control.

Claims (2)

1. A plant for the integrated purification of waste and drinking water, comprising an input tank with a vacuum-ejection treatment unit installed therein, a reagent dosing unit, an electrocoagulation treatment unit, a water degasser tank, a gravity clarification unit, a filtration unit, a purified water accumulation unit, wherein the output of the input tank is hydraulically connected to the electrocoagulation treatment unit, including power sources and an electrolyzer with soluble electrodes in the form of aluminum or iron rods, wherein the output of the electrocoagulation treatment unit is hydraulically connected to the degasser tank, one of the outputs of which is hydraulically sequentially connected to the clarification unit, the filtration unit, the purified water accumulation unit, characterized in that each of the electrodes of the electrolyzer is connected by an air duct to a compressor, wherein a pump is installed at one of the outputs of the degasser tank, feeding part of the purified water back to the electrolyzer. 2. The installation according to item 1, characterized in that a flow laminator is installed inside the clarification unit tank, which makes it possible to reduce the turbulence of the incoming flow of the liquid being purified.