RU2042651C1 - Method and device for deep treatment of sewage - Google Patents

Abstract

FIELD: public services. SUBSTANCE: method involves a stage of biological filtration followed by aeration and settling. The initial biological treatment is carried out by biological filtration through a multilayer filtering charge with immobilized microorganisms, followed by treatment in the underlying zones. Simultaneously the sewage is nitrified-denitrified and settled after which the biologically-treated sewage is finally treated physicochemically by filtration through a multilayer filter containing a layer of peat in some cases modified with a polymeric cation, a layer of zeolite in some cases modified with a polymeric cation, a layer of peat-zeolite mixture and a layer of zeolite. Any materials of the filtering layers can be modified with polymeric cation. The invention also comprises a device for the realization of the claimed biochemical treatment method comprising a casing with a biofilter, an aeration zone underneath, separated by a vertical partition from the settling zone. The biofilter is charged with at least two layers of packings with a highly-developed surface and a high porosity increasing from top down along the water flow, the aeration zone has pneumatic aerators and an airlift aerator filled with a packing, the casing also has the denitrification and degassing zones hermetically closed with a cover. EFFECT: highly efficient treatment of sewage in a compact device. 2 cl, 1 dwg 1 tbl

Description

 The invention relates to deep wastewater treatment, in particular to the wastewater treatment of food industries, such as dairies. The invention also includes a device for implementing the proposed method.

 The problems of deep wastewater treatment are of great environmental importance. A common way to treat wastewater from mechanical impurities is the introduction of coagulants (flocculants), followed by filtration through a layer of sorbent, which retains not only mechanical impurities, but can also absorb some harmful impurities dissolved in water.

 A known composition for wastewater treatment from suspended solids, consisting of polyacrylamide, cationic polyelectrolyte and chlorides of ferrous, ferric, aluminum, potassium, sodium, calcium and magnesium. Such a composition allows for the purification of water from fine particles.

 A known method of wastewater treatment, in which for the flocculation of colloidal solid particles contained in the stream entering the primary clarifier, use a high molecular weight flocculant produced by microorganisms located in aeration tanks with a high content of nutrients. The upper clarified layer from the primary clarifier merges into this tenk.

 It is known to use ion-exchange zeolite in sodium form in conjunction with finely divided calcium hydroxide to purify or maintain the purity of stagnant, mobile and / or moderately flowing waters, for example, garden ponds, swimming pools, aquariums.

 The use of a known composition can prevent the growth of algae in ponds.

 A known method of wastewater treatment from suspended particles, in which water is contacted with zeolitized tuff in the presence of a cationic polyelectrolyte polymer based on diallyldialkylammonium halide or phosphate with a mass ratio of tuff polymer equal to 1: (0.0001-0.01).

 However, this method has limited application and is unsuitable for deep wastewater treatment, since it only removes suspended particles.

 The introduction of peat in a composition based on a zeolite modified with a copolymer based on quaternary diallyldialkylammonium salts allows increasing the degree of purification of wastewater, especially mining enterprises, by removing a significant part of the cations of heavy metals and halides.

 A significant part of the wastewater, in addition to suspended particles, also contains organic and mineral substances dissolved in it. Such wastewater includes domestic sewage, wastewater from food production, in particular dairies, as well as wastewater from wood-processing industries, in particular paper-making. Deep treatment of such wastewater requires complex plants, including both cleaning from mechanical impurities and decomposition and cleaning from organic impurities.

 There is, for example, a known method of wastewater treatment for pulp and paper production using the TAMAN anaerobic process, developed and implemented by the Finnish Tampella joint-stock company. This process involves the partial purification of the waters of the debarking shop in an aerated pond. Wastewater from the pulp mill and from paper machines is treated in anaerobic reactors after pre-treatment. Wastewater treated in anaerobic reactors is sent to an aerated pond. Pretreatment of wastewater before the anaerobic process involves adjusting the pH and supplying nutrient salts. The anaerobic process includes a two-stage formation of acids and methane fermentation, the resulting bigase is sent to the boiler for combustion. Removal of suspended solids is carried out in sumps, followed by filtration. The disadvantage of this method is its bulkiness.

 A device for biochemical wastewater treatment, containing a pump, a discharge line with a hydrodynamic emitter of acoustic vibrations as a source of obtaining a fine air-water mixture for aeration of wastewater, connected to the aeration tank by a sump with an airlift activator mounted in it along the axis and cassette nozzle immobilized on it microorganisms. The disadvantage of this device is the need for significant circulation of treated wastewater pumped into the discharge line with a hydrodynamic emitter, which leads to an overestimation of the volume of the sump.

 A device for biochemical wastewater treatment is also known, comprising a housing in which the loading material is placed in layers. One or more layers form a cleaning chamber. The loading material for the layers and chambers is chosen homogeneous. Between the chambers there are placed distributors of perforated hole-type, chute-type wastewater in the form of a backfill or flat charge with fraction sizes ⌀ 15-50 mm and a height equal to 2-5 fraction sizes. The disadvantage of this facility is the need for wastewater recycling in order to dilute the effluent entering the treatment.

 Closest to the proposed is a device for biochemical wastewater treatment, containing a cylinder-conical body, divided by partitions into aeration and sedimentation chambers, a biofilter, a mixing chamber, a circulation pump and process pipelines. The device is equipped with a pallet placed under the biofilter with a central hole mounted under it, a supply pipe with a vortex funnel, and also air caps placed in the aeration chamber. The disadvantage of this device is the significant energy consumption for the recycling of treated wastewater to dilute the effluent entering the treatment, which increases the dimensions of the settling zone, the need for large deepening to ensure spontaneous sliding of the washed from the biofilm loading to the sludge pipe, insufficient aeration efficiency in the stabilization zone.

 The purpose of the invention is the development of a compact and highly effective method for deep wastewater treatment containing a large amount of organic impurities, in particular domestic sewage and wastewater of food production.

 Another objective of the invention is the development of a device for implementing the method.

 This goal is achieved using a method of deep wastewater treatment, including biofiltration, followed by aeration and sedimentation and additional physico-chemical post-treatment on the air filter, biofilm, sump and filters. For this, the initial purification is carried out by biofiltration through a multilayer charge with various design parameters, at the aeration stage, a charge with immobilized microorganisms is used, while nitrification-denitrification and retardation of treated wastewater are carried out at the same time, after which physicochemical purification of biologically treated wastewater is carried out by filtering them through multilayer filters, including layers of peat modified with a polymer cation, a peat zeolite mixture, mode a modified polymer cation; and a modified and / or unmodified zeolite.

 A device for implementing the proposed method comprises a housing with a biofilter, an aeration zone located beneath it, separated by a vertical partition from the settling zone, the biofilter is loaded with at least two layers of nozzles with a highly developed surface and high porosity, which increases from top to bottom, the aeration zone is equipped with pneumatic aerators and airlift -aerator and is filled with a nozzle; in the case there are also denitrification and degassing zones, which are hermetically closed by a lid.

 The drawing shows a device that implements the proposed method. The device consists of a cylindrical housing 1, divided into compartments 2, 3 and 4. The lower part of the housing 1 is immersed in the tank 5. The compartments 2 and 4 are filled with a nozzle in the form of rings and are separated from the compartment 3 by supporting grids. The compartment 3 is filled with vertically installed plastic pipes and is separated from the compartment 4 by a grill 6. The liquid leaving the compartment 3 is sent to the central part of the compartment 4 by the confuser 7. In the central part of the compartment 4 there is an airlift aerator 8 through which the activated sludge is recycled through the pipeline 9. Under the lower supporting grid mounted aerators 10.

 The tank 5 is divided into zones: degassing 11, settling 12 and denitrification 13. The degassing and denitrification chambers of the tank 5 are closed by a sealed cover 14. The denitrification chamber 13 is equipped with an overflow 15.1, which regulates the circulating flow of the sludge mixture from the compartment 4 with plastic pipes vertically installed between the supporting gratings 16 and the bottom slit 17. The degassing chamber 11 is equipped with an overflow 15.2, and in its central and bottom parts there are slots for separating the flows.

 The lagging chamber 12 consists of a settling zone, in which thin-layer modules 18 and a clarified water collecting tray 19 are mounted, and a conical bottom 20, from which activated sludge is discharged via pipeline 9 to compartment 4. Excess activated sludge is removed through pipelines with a valve 21.

 After biochemical treatment, clarified water is sent to a multilayer filter for deep physicochemical purification. Structurally, this filter can be made one- or two-stage, depending on the requirements for the quality of the treated water, dimensions, installations, etc. The drawing shows one of the options using a two-stage filter 22 and 23.

 The first cascade 22 is a three-layer filter, the first layer 24 consists of optionally modified peat, the second layer 25 of peat modified with a polymer cation of the peat zeolite mixture, and the third layer 26 of modified zeolite. The second cascade 23 is a two-layer filter, the first layer from the bottom 27 consists of a modified zeolite, and the second layer 28 of unmodified zeolite. Water after physico-chemical deep purification is discharged through pipeline 29.

 The method of deep wastewater treatment is carried out in the proposed device as follows.

Wastewater with previously removed large mechanical impurities is fed into the housing 1, where they are evenly distributed over the surface of the compartment 2 loaded with a nozzle with a highly developed surface and high porosity (specific surface and porosity are not 100 m ² / m ³ and 70%, respectively), where the main part (mass) of easily and medium-oxidized organic pollutants is removed.

 Further oxidation of organic pollutants (up to 60% of their initial amount) is carried out in a non-siltable highly porous (porosity of at least 80%) compartment 3. The aeration of the compartments 2 and 3 is carried out by the air coming from compartment 4 due to a sealed cover 14 that covers the degassing zone 11 and denitrification 13, which also ensures the freezing of nozzles compartments 2 and 3 in the winter.

Concentrated wastewater pre-treated in compartments 2 and 3 is supplied by confuser 7 for final purification and nitrification to the central area of compartment 4, where they are mixed with the circulating stream created by the air-lift aerator 8 and filtered through a layer of inert nozzles in the form of rings with highly developed porosity (not less than 100 m ² / m ³ and 70%, respectively) and which occupies at least 50% volume of the compartment 4. The amount of the nozzle mounted on the biofilm with microorganisms floating 2-3 times higher than those systems with a Rim floating activated sludge, that the same factor accelerates the cleaning process, while ensuring the fastening on the nozzle-nitrifying microorganisms.

 Aeration of the volume of compartment 4 with the nozzle is carried out by pneumatic aerators 10 and airlift aerator 8 in countercurrent mode.

 Using a movable spillway 15.2, the amount of circulating flow entering the degassing zone 11 is regulated, part of which enters the settling zone 12 with a thin-layer module 18, and after clarification is collected by the tray 19 and sent for further treatment. The activated sludge settled in the conical bottom 20 of the settling tank 12 partially returns through the pipeline 9 to the biotank, partially via the pipeline 21 it is removed for processing and drying (not shown in the drawing).

 Using a mobile weir 10.1, the amount of circulating flow entering the denitrification zone 13 is regulated, which is not less than 50% filled with a non-siltable highly porous (porosity of at least 80%) nozzle, on which denitrifying microorganisms are fixed, which restore oxidized forms of nitrogen nitrites and nitrates under oxygen-free conditions.

 The sludge mixture is returned to compartment 4 from the degassing zone 11 and denitrification 13 through the bottom slit 17.

 After biochemical purification, water from the collecting tray 19 is sent to a two-stage multilayer filter 22, 23. Through the first cascade, water flows by gravity from top to bottom, first through the first layer 24, consisting of optionally modified peat, then through the second layer 25, consisting of a peat mixture made of a polymer cation and a third layer 26 consisting of a modified zeolite. Water is passed through the second cascade 23 from the bottom up first through a layer 27 consisting of a modified zeolite, then through a layer 28 consisting of an unmodified zeolite. Between cascades 22 and 23, a valve 30 is provided for discharging purified water if the desired cleaning depth is reached when passing only through the first cascade. The number of filtering surfaces and their quality characteristics can be changed depending on the characteristics of the incoming water for aftertreatment.

 The invention is illustrated in the examples given in the table, which show how it can be implemented in practice, but do not limit it.

 PRI me R 1. For deep biological treatment wastewater was sent to a milk processing plant with BODp up to 3060, COD up to 3750 and with suspended particles up to 1650 mg / l. After biological treatment according to the proposed method, the list of residual contaminants in mg / l after settling for 1.5 hours amounted to: suspended solids 12.0; COD 65.0 and BOD 15.

 After passing these waters through a multilayer filter for deep physico-chemical post-treatment, consisting of layers of peat, zeolite, peat zeolite mixture containing 80% peat and 20% zeolite, modified with a 0.1% solution of poly-N, N-diallyl-N , N-dimethylammonium chloride, and two layers of zeolite, receive purified water with the following indicators: suspended solids 0.5; COD 10.0 and BOD 5.0 mg / L.

 Example 2. It is carried out according to the method of example 1, but a multilayer filter consists of unmodified layers.

 PRI me R s 3-8. They are carried out according to the method of example 1, but instead of a multilayer filter for deep physico-chemical post-treatment, a single-layer filter is used, each time changing the filter material. The results for each filter are shown in the table.

 Thus, it can be seen from the data in the table that the use of any of the filter materials separately does not provide deep wastewater treatment, and even slightly affects the effluent performance, however, the use of the organic component of the filter in the sequence of layers indicated in Example 1 allows one to obtain practically pure effluents .

 The proposed method and device allows for a more compact and highly efficient way to deeply treat wastewater containing a large amount of organic impurities.

Claims (3)

 A method of deep purification of wastewater containing a large amount of organic contaminants, including biofiltration followed by aeration and sedimentation, characterized in that the initial bio-treatment is carried out by biofiltration through a multilayer charge, the subsequent aeration is carried out with immobilized microorganisms, while nitrification-denitrification and sedimentation processes are carried out simultaneously wastewater, after which physicochemical purification of biologically treated wastewater is carried out by means of their fil filtration through a one-two-stage multilayer filter, including a peat layer, in some cases modified with a polymer cation, a layer of peat zeolite mixture, also in some cases modified with a polymer cation, and a layer of modified and / or unmodified zeolite.  2. The method according to claim 1, characterized in that polydiallyldimethylammonium chloride is used as the polymer cation.  3. Device for deep wastewater treatment, comprising a housing with a biofilter, an aeration zone located beneath it, separated by a vertical partition from the settling zone, characterized in that the biofilter is loaded with at least two layers of nozzles with a highly developed surface and high porosity, which increases from top to bottom , the aeration zone is equipped with pneumatic aerators and airlift-aerator and is filled with a nozzle, in the case there are also denitrification and degassing zones, which are hermetically closed by a cover.

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