WO2021255542A1

WO2021255542A1 - Wastewater treatment method

Info

Publication number: WO2021255542A1
Application number: PCT/IB2021/053968
Authority: WO
Inventors: Сергей Яковлевич ЧЕРНИН
Original assignee: Сергей Яковлевич ЧЕРНИН
Priority date: 2020-06-17
Filing date: 2021-05-10
Publication date: 2021-12-23
Also published as: RU2740993C1

Abstract

The invention can be used for sewage, drainage water and sludge water treatment. The contaminated water is subjected consecutively to a primary cleaning to remove mechanical impurities, cleaning by an electroflotation method, ultrafiltration, first step demineralization by reverse osmosis, second step demineralization of the permeate by reverse osmosis, and a final cleaning to remove ammonia ions. The primary cleaning is performed in a hydrocyclone. After ultrafiltration, the water is subjected to a two-step ozone treatment in labyrinth columns. The permeate obtained is returned to the first step of demineralization by reverse osmosis. The final cleaning of the water to remove ammonia ions is carried out on a filter with a packed zeolite bed. The method provides an increase in the degree of purification of the wastewater.

Description

WASTE WATER PURIFICATION METHOD

The invention relates to the field of environmental protection and can be used for purification of waste, drainage and oversludge waters with increased salt content, containing complex difficult-to-oxidize organic impurities up to the water quality standards of water bodies of fishery significance, including water bodies of specially protected natural areas (SPNA). The invention relates to multistage physicochemical methods for reagent treatment of contaminated industrial wastewater. The method can be applied at industrial facilities and facilities for the disposal of production and consumption waste for the treatment of wastewater, including technological, drainage and over-sludge wastewater to the required standards before being discharged into water bodies of fishery significance, including water bodies of protected natural areas or in recycling systems. water supply enterprises.

There is a known method of purification and disinfection of water from natural highly contaminated sources, which is implemented by an installation (RU 2652705 С 1, publ. 28.04.2018), containing a preliminary coarse mechanical cleaning filter followed by feeding to the contact capacity of ozonation. The volume of the contact container is designed so that the time of contact between water and ozone is at least 20 minutes. The water treated with ozone then goes to the ultrafiltration module, after which either all the water to be treated or only a part of the water to be treated goes to the reverse osmosis membranes, depending on the required degree of desalination. The hydraulic efficiency of the installation, taking into account the reverse osmosis module, is about 60%. Permeate (purified water) enters the storage tank and then for the needs of the consumer, and the concentrate, after the reverse osmosis membranes, enters the storage tank, from which partial circulation is provided through the reverse osmosis module, or the resulting concentrate is discharged. In general, the installation is quite simple and economical in operation, it allows you to obtain drinking water, but at the same time, the method it implements has a number of disadvantages:

1) there is no water treatment with chemical reagents, which in general reduces the depth and degree of purification;

2) a single-stage contact reactor was used, which is insufficient for waters with a complex chemical composition of impurities due to the difference in the rate of oxidation of the components;

3) used a one-stage reverse osmosis desalination of water both in terms of permeate and concentrate, which in general reduces the overall hydraulic efficiency;

4) the method is intended for the purification of highly polluted, but natural waters and is not applicable for industrial effluents of complex chemical composition; There is a known method of wastewater treatment to obtain purified water and disinfected waste (RU 2701827 С 1, publ. 01.10.2019), which allows you to purify wastewater to the water quality standards of water bodies of fishery significance. Wastewater treatment to obtain purified water and disinfected waste includes wastewater treatment by means of a block-modular complex, in which preliminary mechanical wastewater treatment from large solid inclusions is carried out, followed by biological treatment and water saturation with air oxygen and additional treatment. Additional purification of water takes place in the adsorption and chemical oxidation or decarbonization module, in which organic substances dissolved and suspended in water are oxidized with ozone, and the final additional purification of water to the standards for water quality of water bodies of fishery importance is carried out on a reverse osmosis unit. The sludge and sediments formed during the purification process are sent to the biological treatment module for re-processing, and then the precipitated waste is pumped into the mechanical treatment module, where they are dehydrated, disinfected and briquetted. In general, the method provides a stable cleaning quality in a continuous mode, but at the same time has a number of disadvantages:

1) the presence of a biological treatment module significantly reduces the range of MIC values to the permissible load on activated sludge, as a rule, no more than 240 mg BOD / (g sludge-day);

2) the total salt content of up to 2000 mg / dm ³ is also subject to restriction in the treated water; 3) the water to be treated must not contain mineral or organic toxic compounds;

4) the method is intended for the treatment of only household wastewater or industrial wastewater equivalent in quality.

The closest to the proposed method is the method of purification of drainage waters of landfills of solid domestic waste (RU 2589139 C2, publ. 10.07.2016), which can be used to purify concentrated wastewater with difficult-to-oxidize organic impurities and toxic compounds. The installation for implementing the method includes a series-connected receiving tank, a pump, a self-cleaning filter for mechanical cleaning, electro-flotation destructors of the first and second stages, a tank, a pump, a sump, in front of which a coagulant alkali solution and a flocculant are fed into the water. The lower part of the settler is connected to a sludge compactor, which is connected to a vacuum dewatering unit. The upper part of the sump is connected to a tank to which a pump, a hollow fiber ultrafiltration module, a tank, a pump and a reverse osmosis membrane module of the first stage are connected in series, before which a dechlorinating agent, a solution for adjusting pH and an inhibitor of precipitation on the membrane are fed into the water, then a packed column, after which sulfate ions are added to the permeate, a second-stage reverse osmosis module 32, after which an alkali solution is added to the water, two ion-exchange filters to remove sulfide ions and traces of ammonium, and an ultraviolet sterilizer. Cleaning method drainage waters of landfills at this installation includes the following stages: two-stage electrochemical cleaning on electro-flotation destructors with the release of active chlorine and hydroxyl radicals at the anode, settling, ultrafiltration, two-stage reverse osmosis separation by permeate, water treatment with ion-exchange resins and ultraviolet sterilization. The invention makes it possible to purify drainage waters of landfills of solid domestic waste with a complex composition of organic inclusions up to the MPC requirements for water of fishery reservoirs, however, it is not devoid of disadvantages:

1) high energy consumption at the stage of electrochemical cleaning;

2) increased formation of flushing water at the stage of ion exchange, and, as a consequence, low hydraulic efficiency;

3) there is no stage of reducing the volume of the resulting concentrate.

Nevertheless, due to its purpose and the presence of similar features, this method is adopted as a prototype.

The technical problem solved by the proposed invention is to increase the degree of purification of waste, drainage and over-sludge waters of industrial facilities and objects of disposal of production and consumption waste, increase the overall hydraulic efficiency and reduce the total volume of utilized concentrate.

The technical problem is solved by the method of purification of polluted industrial waters, which consists in the fact that the polluted water is subjected to sequential primary treatment from mechanical impurities, electroflotation purification, ultrafiltration, reverse osmosis desalting of the first stage, reverse osmosis desalting of the second stage by permeate and final purification from ammonium ions, while, according to the invention, the primary purification of contaminated water from mechanical impurities is carried out using a hydrocyclone, after primary purification the water is subjected to coagulation in a tubular coagulator, and after ultrafiltration the water is subjected to two-stage ozonation in labyrinth columns, the concentrate obtained in the first stage of reverse osmosis desalting is subjected to reverse osmosis desalination of the second stage in terms of concentrate, and the permeate obtained in this second stage is returned to the first stage of reverse osmosis final desalting water from ammonium ions is carried out using a filling filter with zeolite.

The technical result of the invention, which consists in increasing the degree of purification of polluted waters, is achieved through the implementation of two-stage ozonization of the treated water with an increased area of interaction with ozone in the labyrinth columns.

The use of a zeolite backfill filter instead of an ion-exchange filter makes it possible to increase the degree of purification, as well as reduce the formation of flushing water and increase the overall hydraulic efficiency.

Reverse osmosis desalting of the second stage in terms of concentrate and return of the permeate obtained in the second stage to the first stage of reverse osmosis desalting allows to reduce the volume of the resulting recycled concentrate.

In addition, after two-stage ozonation and after ultrafiltration, the water is subjected to control purification from mechanical impurities.

To reduce the water content in the sludge, the sludge obtained during the primary purification of contaminated water and during electroflotation purification, as well as the wash water obtained during ultrafiltration, is sent to a sump, the water from which is returned to the stage of primary purification from mechanical impurities.

The invention is illustrated by drawings.

FIG. 1 shows a process flow diagram of an installation for implementing the proposed method for purifying polluted industrial waters.

FIG. 2 is a diagram of the labyrinth columns of the ozonation unit.

An installation for purification of waste, drainage and oversludge waters of objects and objects of disposal of production and consumption waste (Fig. 1) contains a series-connected receiving tank-storage 1, a centrifugal pump 2, a device for primary water purification from mechanical impurities, which is a hydrocyclone 3, tubular coagulator 8. Tank 5 with coagulant solution and tank 7 of sodium hydroxide solution are connected to the pipeline in front of the tubular coalescer by means of metering pumps 4 and 6 to equalize pH, respectively. Tubular coalescer 8 is connected to the electroflotator 14 by means of a pipeline, to which a container 10 with a flocculant solution is connected by means of a metering pump 9. The electroflotator 14 is connected to a direct current source 15 (DCS). The outlet of the electroflotator 14 by means of a centrifugal pump 16 is connected to the inlet of the ozonation unit, which includes two successively installed labyrinth columns 17, 18 of ozonization (Figs. 1, 2). A circulation circuit is connected to each column 17 (18), which includes a circulation pump 19 (21) and an ejector 20 (22). The ozone generator 45 is connected to the suction pipe of the ejector 22 of the second column 18 downstream of the water flow, which is connected with its upper part to the suction pipe of the ejector 20 of the first column 17.

Labyrinth columns 17, 18 ozonation can be direct-flow or counter-flow. In this diagram (Fig. 1, 2), the first column 17 along the flow of water is counter-current, and the second column 18 is direct-flow. Each labyrinth column 17, 18 (Fig. 2) includes a vertical body 46, inside which there are horizontal labyrinth partitions 47 and a bubbler 48, the outlet openings of which for the outlet of the ozone-oxygen mixture are located in the lower part of the body 46. An overflow collection pocket is formed in the body 46 49 for treated water, which goes further to ultrafiltration. In the first downstream column 17, water is withdrawn from the bottom of the body 46 and is introduced into the bottom of the body 46 of the second column 18.

The outlet of the second column 18 ozonization by means of a centrifugal pump 23 through the first control cartridge filter 24 for mechanical cleaning is connected to the unit 25 ultrafiltration, which includes one or more ultrafiltration membrane water purification modules. An intermediate tank 26, a centrifugal pump 27, a carbon filter 28, a second control cartridge filter 35 for mechanical cleaning, a high-pressure pump 36, a desalination unit, an intermediate tank 42, a centrifugal pump 2 and an ammonium ion filter, which is a fill filter 44 with zeolite.

The outlets of the hydrocyclone 3 and the electroflotator 14 for sludge and the outlet of the ultrafiltration unit 25 for wash water are connected through an intermediate tank 11 and a sludge pump 12 to a thin-layer lamellar flow-through clarifier 13, the outlet of which for water is connected to a receiving storage tank 1.

Tanks 30, 32 and 34 with antiscalant, sulfuric acid solution and sodium bisulfite are connected to the pipeline between the carbon filter 28 and the mechanical cleaning filter 35 by means of metering pumps 29, 31 and 33, respectively.

The desalination unit includes a reverse osmosis module 37 of the first stage and a reverse osmosis module 39 of the second stage for permeate, as well as a reverse osmosis module 41 of the second stage for concentrate, connected in series by means of a high pressure pump 38. In this case, the outlet of the reverse osmosis module 37 of the first stage for the concentrate is connected by means of a high pressure pump 40 to the inlet of the reverse osmosis module 41 of the second stage for the concentrate, the outlet of which is connected to the inlet of the high pressure pump 36. The method of purification of polluted industrial waters is carried out as follows.

Waste, drainage or oversludge waters of industrial facilities and production and consumption waste disposal facilities are fed into the receiving storage tank 1, then pump 2 for primary treatment into hydrocyclone 3. Hydrocyclone 3 allows water to be purified from mechanical impurities up to 10 microns in size. From the processed water flow, under the action of centrifugal forces, heavier mechanical impurities move to the lower part of the apparatus cone and, in the form of sludge in a volume of not more than 10% of the main flow, are discharged into the intermediate tank 11 and then by the pump 12 into the thin-layer lamellar flow sump 13, water separation and the sediment is organized according to the countercurrent scheme. Clarified water goes back to the receiving storage tank 1, and the compacted sludge for disposal. After primary cleaning on a hydrocyclone 3, a coagulant solution is introduced into the stream of purified water by a dosing pump 4 from a tank 5, and to equalize the pH, a sodium hydroxide solution by a dosing pump 6 from a tank 7. To increase the contact time, the treated water passes through a tubular coalescer 8, after which, for to intensify the cleaning process, the flocculant is dosed into the water flow by the dosing pump 9 from the tank 10.

Further, the stream of purified water is directed to the electroflotator 14 to extract heavy metals, reduce COD (chemical oxygen demand), BOD (biochemical oxygen demand) and the amount of suspended particles. The water to be purified enters the lower part of the electroflotator 14, after filling the installation with liquid, turn on the constant current source 15 and apply voltage to the electrodes. As a result of water electrolysis, gas bubbles are released on the surface of the electrodes, which, rising upward, interact with dispersed particles of pollution to form flotation complexes "particle-gas bubbles". The density of the resulting flotation complexes is less than the density of water, which causes them to rise to the surface of the water and the formation of a foam layer - flotation sludge. The flotation sludge is periodically removed from the water surface with a scraper conveyor. Removal of flotation sludge occurs in a volume of 2% of the flow entering the electroflotator 14 into the intermediate tank 11 and then by the pump 12 into the thin-layer lamellar flow-through settler 13, the separation of water and sediment is organized according to a counter-current scheme. Clarified water goes back to the receiving storage tank 1, and the compacted sludge for disposal.

Further, the water to be purified is subjected to double ozonation in two labyrinth columns 17, 18 installed in series. Ozone-oxygen mixture is synthesized from concentrated oxygen and supplied from the ozone generator 45 to the ejector 22 of the second column 18, where it is mixed with the stream of purified water. Unreacted in the second column 18 ozone is supplied to the ejector 20 of the first column 17, where it is mixed with a "fresh" portion of the purified water. To achieve the required mixing of the flow with the ozone-oxygen mixture, the purified water in the circulation mode is supplied to the ejector 20 by means of the pump 19 to the ejector 22 by means of the pump 21. Waste ozone- the oxygen mixture (air mixture) enters the destructor (conventionally not shown) and then into the atmosphere. From the labyrinth columns 17, 18, the purified water by the pump 23 is discharged to the control cartridge filter 24 for mechanical cleaning, which is used to clean the liquid flow from insoluble mechanical impurities before the ultrafiltration unit 25. The drainage is removed in a volume of 0.5% of the incoming flow to the filter 24 to the sump 13 through the intermediate tank 11.

For guaranteed removal of organic impurities and small particles from the stream of purified water, ultrafiltration modules of the ultrafiltration unit 25 are used. Ultrafiltration membranes operate on the “inside-out” principle, which means that the supplied water flow in filtration mode flows from the inside of the capillaries to the outside, and in the backwash mode, water flows in the opposite direction, that is, from the outside to the inside of the capillaries. The modules operate in tangential mode to prevent excessive build-up of deposits on the membrane surface. High speeds of tangential flow create turbulence in the water supply channel, providing a high efficiency of cleaning the surface from accumulated contaminants, which is especially effective for water with a high content of insoluble suspended matter. To maintain a high flow rate, part of the resulting concentrate is returned to the ultrafiltration modules (recirculation) and mixed with the main stream of treated water. The remaining concentrate in the amount of 20% of the incoming flow to the ultrafiltration modules is discharged to the settler 13 through the intermediate tank 11. For Maintaining the productivity of the ultrafiltration modules during operation are subjected to short impulse washings with alternating acid and alkaline phases. The wash water from the ultrafiltration unit 25 is directed to the settler 13. The water purified from the main contaminants is collected in the intermediate tank 26, from where the pump 27 is fed to the carbon filter 28 to remove volatile phenols and possible residues of oil products. Further, the water to be purified through the control cartridge filter 35 of mechanical cleaning by the pump 36 is supplied to the desalination unit to the reverse osmosis module 37 of the first stage. Before entering the reverse osmosis membranes, an antiscalant, a solution of sulfuric acid and sodium bisulfite (antioxidant) are dosed into the flow of purified water by metering pumps 29, 31, 33. Solutions of chemical reagents are prepared in containers 30, 32, 34. On reverse osmosis membranes, the purified water is divided into two streams: permeate - demineralized pure water and concentrate - water containing dissolved salts. Separation into permeate and concentrate on the first stage reverse osmosis module 37 is carried out in a ratio of 75/25 as a percentage of the incoming stream. The permeate of the first stage is supplied by a pump 38 to the second stage reverse osmosis module 39 by permeate, where it is divided into the second stage permeate and the second stage concentrate in a ratio of 80/20 in percentage. The concentrate of the first stage, formed on the reverse osmosis module 37, in order to increase the degree of permeate recovery, is supplied by the pump 40 to the reverse osmosis module 41, where it is re-divided into permeate and concentrate in a 60/40 ratio. The permeate from the reverse osmosis module 41 enters the inlet of the pump 36, and the concentrate for disposal. The second stage concentrate formed on the membranes of the reverse osmosis module 39 is partially fed to the inlet of the pump 38 and partly to the inlet of the pump 36. The permeate after the second stage of reverse osmosis purification enters the intermediate tank 42, from where the pump 43 is fed to the final purification stage - purification from ammonium ions. Ammonium ions are removed from the fill filter 44. The filter is filled with natural zeolite - clinoptilolite. The total hydraulic efficiency of treatment according to the proposed scheme is at least 85% of the contaminated water entering for treatment.

Further, the permeate that meets the water requirements of fishery facilities is supplied to open water bodies.

Claims

Claim

1. A method for purifying polluted industrial waters, which consists in the fact that the polluted water is subjected to sequential primary purification from mechanical impurities, electroflotation purification, ultrafiltration, reverse osmosis desalting of the first stage, reverse osmosis desalting of the second stage by permeate and final purification from ammonium ions, characterized in that primary purification of contaminated water from mechanical impurities is carried out using a hydrocyclone, after primary purification, the water is subjected to coagulation in a tubular coagulator, after ultrafiltration, the water is subjected to two-stage ozonation in labyrinth columns, the concentrate obtained in the first stage of reverse osmosis desalination is subjected to reverse osmosis by desalting, and the second stage The permeate obtained at this second stage is returned to the first stage of reverse osmosis desalination, and the final water purification from ammonium ions is carried out using a filling filter with zeolite.

2. A method according to claim 1, characterized in that after two-stage ozonation and after ultrafiltration, the water is subjected to control purification from mechanical impurities.

3. The method according to claim 1, characterized in that the sludge obtained during the primary purification of contaminated water and during electroflotation purification, as well as wash water, obtained by ultrafiltration are sent to a settling tank, the water from which is returned to the stage of primary purification from mechanical impurities.