RU237481U1 - First stage surface wastewater treatment plant - Google Patents

Abstract

The utility model relates to devices for treating stormwater and is intended for the preliminary separation of suspended solids of organic and mineral origin with large and medium hydraulic sizes from wastewater. The technical result of the utility model consists in creating a compact and easy-to-use first-stage device for treating surface wastewater with the effective retention of suspended particles with a hydraulic size of 0.05-5 mm/s. The first-stage device for treating surface wastewater comprises a housing with a partition dividing the housing into first and second chambers, wherein a tangential sand trap with a comb-type weir is installed in the first chamber of the housing, and a thin-layer settling module is installed in the second chamber. 2 c.p. fils, 3 figs.

Description

The utility model relates to devices for the purification of surface (melt and storm) wastewater from highways, residential areas, industrial enterprises, public areas and is intended for the preliminary separation of suspended substances of organic and mineral origin with large and medium hydraulic size from wastewater.

A wastewater treatment plant is known to operate according to the following scheme: wastewater flows from the inlet of the plant, passing successively through a coarse settling zone and thin-layer elements made of corrugated plates, with channels for the removal of petroleum products, where coarsely dispersed petroleum products, suspended matter, and some finely dispersed contaminants are retained. The wastewater then enters a floating-bed filter and a sorption filter, where it undergoes deep final purification by filtration and sorption of finely dispersed and dissolved impurities (Russian Federation Patent for Utility Model No. 86182, published August 27, 2009).

A settling tank-oil separator is known, comprising a settling tank-accumulator, a thin-layer settling unit, and a filter element, arranged in series in a tank in the direction of flow of the liquid being processed. The tank is equipped with pipes for the inlet of the treated wastewater, the outlet of the clarified liquid, devices for removing sediment and removing oil-containing substances, and a coalescer is installed between the thin-layer settling unit and the filter element (Russian Federation Patent for Utility Model No. 47396, published August 27, 2005). Disadvantages of the known devices include the large overall dimensions of the units.

A sewage pumping station body is known, consisting of a base and sections made of polyethylene, connected to each other to form a single structure, wherein each section is made two-chambered by connecting sections of two pipes of a round open cross-section by extrusion welding, each section is equipped with flanges made of polyethylene and installed on the ends (RU Patent for Utility Model No. 220234, published 09/04/2023).

A device for treating surface wastewater is known. It comprises a housing made of fiberglass pipes and consisting of a vertical section and an adjacent inclined section. The vertical section's upper portion contains an open hydrocyclone with a tangential outlet and a sludge discharge pipe with a gate valve and a check valve installed thereon. The lower portion of the vertical section contains a hopper with a conical bottom for sludge and a sludge removal device. The housing, at the junction of the vertical and inclined sections, is equipped with a baffle plate that does not extend to the bottom of the junction, with a solid upper portion and a perforated lower portion. A thin-layer settling module, an oil product collection device (an oleophilic belt skimmer), a semi-submersible and overflow baffle, and a submersible pump for removing purified water, connected to a purified water outlet pipe, are installed sequentially along the inclined section along the wastewater flow (Russian Federation Patent for Utility Model No. 207418, published October 27, 2021). This device has been adopted as a prototype. The disadvantages of this known device include insufficient removal of suspended particles, mechanical impurities, and oil products.

The technical objective of the utility model is to improve the quality of wastewater treatment while reducing the occupied space during operation of the first stage device for surface wastewater treatment.

The technical result of the proposed technical solution consists in the creation of a compact and easy-to-use device for the first stage of surface wastewater treatment with effective retention of suspended particles of hydraulic size from 0.05 to 5 mm/s.

The technical result is achieved due to the fact that the device for the first stage of surface wastewater treatment (hereinafter referred to as the device) comprises a housing with a partition dividing the housing into first and second chambers, in the space of the first chamber of the housing a tangential sand trap with a comb-type overflow drain is installed, and in the space of the second chamber a thin-layer settling module is installed, wherein the comb-type overflow drain of the tangential sand trap is equipped with an overflow branch pipe passing through an opening in the partition dividing the housing into chambers.

In a particular case of execution, a waste collection mesh is installed inside the tangential sand trap.

In a particular case of execution, a partition is installed in the space of the second chamber of the housing for the installation of a thin-layer settling module.

The essence of the utility model is explained by the following graphic materials.

Fig. 1 shows the device in cross section;

Fig. 2 shows the device – top view;

Fig. 3 shows the device in isometric view.

The device comprises a housing 1 with a technical well 2 for servicing process equipment, inside the housing 1 a tangential sand trap 3 with a comb-type drain 4 and a waste collection mesh 5 is installed, as well as a thin-layer settling module 6 and an airlift system 7.

Housing 1 is based on a spiral-wound pipe and can be made of low-density polyethylene. The housing is mounted on a base plate. The base plate is made of concrete, the thickness of which is determined based on a strength calculation. Housing 1 is constructed as a two-chamber structure, for example, by extrusion welding sections of two open-section round pipes. When the pipe sections are joined, the housing cross-section resembles the figure "eight." Housing 1 is equipped with oval flanges 9 made of a polymer material, such as polyethylene, and mounted on the ends of housing 1 using extrusion welding. The base plate is rigidly connected to the lower flange 9.

The diameter of the pipes used to construct housing 1 is selected based on the size of the equipment housed within it, as well as the required tank volume and the amount of incoming wastewater. Furthermore, the pipes can be spiral-wound and have the same or different diameters, depending on the technical specifications. Housing 1 is divided into two chambers by partition 10, which is made of a polymer material. A hole is made in partition 10 for the installation of nozzle 11.

In the upper flange 9, an opening is made for installing a technical well 2, which is necessary for servicing the tangential sand trap 3, the thin-layer settling module 6, and also for organizing the process of pumping sediment from the bottom of both chambers of the body 1.

A waste collection mesh 5 is installed in the interior of the tangential sand trap 3, in its upper portion, below the inlet pipe 14, for retaining large debris (leaves, household waste, etc.). The mesh 5 is removable and mounted on guides made on the interior surface of the tangential sand trap 3. The mesh 5 is made of a polymer material or stainless steel.

The first chamber of housing 1 contains a tangential sand trap 3 with a comb-type drain 4, and the second chamber of housing 1 contains a thin-layer settling module 6. Their sequential placement in the device increases the settling efficiency within the compact housing 1 and eliminates the need for bulky, empty settling tanks.

The tangential sand trap 3 is located in the first chamber 15 of the housing 1 filled with water and is designed to remove suspended solids with a large hydraulic size of 0.5-2 mm/s, carried out of the pipelines by a strong flow of water, and heavy fractions of petroleum products.

The tangential sand trap 3 is a cylindrical tank connected to a conical base made in the form of a truncated cone. The angle of inclination of the walls of the conical base to the horizon is from 45° to 60°. This angle of inclination of the cone ensures the effective sliding of the separated sediment to the bottom of the first chamber 15. In the upper part of the cylindrical tank of the tangential sand trap 3, an inlet pipe 14 is installed for the inlet of wastewater, directed tangentially to the inner wall of the cylindrical tank. In the lower part of the conical base, an opening 17 is made for the passage of wastewater and sediment, while a comb-shaped spillway 4 is attached to the outer side of the cylindrical tank of the tangential sand trap 3, consisting of a hermetically fastened shelf of an annular and a comb-shaped barrier, which is a cylindrical shell with an opening intended for the installation of an overflow pipe 11. The upper edge of the comb weir 4 is curved with alternating depressions and projections. The multiple depressions of the comb weir 4 form sills over which the water flow from the cavity of the first chamber 15 flows into the cavity of the comb weir 4. The projections are located between the depressions and partially protrude above the surface of the water flow, serving to evenly distribute the water flow over the sills of the depressions into multiple parallel streams. This reduces the carryover of suspended solids through the comb weir 4, equalizes the hydraulic load on the comb weir 4, and improves the uniformity of water distribution along the length of the comb weir 4. As a result, laminar flow is maintained as the volume of incoming wastewater increases, and the sedimentation of suspended solids before comb weir 4 is not interrupted (effective sedimentation of suspended particles is maintained, with minimal carryover into the second chamber 16 of housing 1). Thus, when using comb weir 4, the carryover of suspended solids through weir 4 is reduced, improving the quality of wastewater treatment for suspended solids and retaining fine suspended solids with a hydraulic particle size of 0.1 to 0.5 mm/s.

Overflow pipe 11 is attached to comb-shaped drain 4 and passes through an opening in partition 10, which divides housing 1 into chambers. Overflow pipe 11 is designed to divert clarified liquid flow from first chamber 15 to second chamber 16 of housing 1.

Tangential sand trap 3 can be made of polyethylene, such as low-density polyethylene. This material allows for a robust structure, easy assembly, and sealed joints, as well as high corrosion resistance and a long service life.

The tangential sand trap 3 is located on supports made of reinforced polyethylene profile pipe, reinforced inside with a metal profile (not shown in the figure).

In the body 1, a sediment removal system is provided, for example, an airlift system 7, which ensures the timely removal of sediment from both the first chamber 15 of the body 1 and the second chamber 16.

Further downstream of the purified water flow is thin-layer settling module 6, designed to retain fine suspended solids with a hydraulic particle size of 0.05-0.1 mm/s during a settling time of 5-10 minutes, as well as floating and settling petroleum products. Thin-layer settling module 6 utilizes the principle of gravity separation of suspended solids from the treated water. In addition to the sedimentation of suspended solids, the bulk of undissolved petroleum products floats to the surface as an oil-gasoline film. This film is also pumped from the surface by airlift system 7.

The proposed device is equipped with a sediment removal system, for example, an airlift system 7 specially developed for this device design for the automatic removal of sand and oil film into a separate container or well (not shown in the figure).

The use of a two-stage settling system using a tangential sand trap 3 with a comb weir 4 and a thin-layer settling module 6 allows for the removal of suspended solids with a hydraulic particle size greater than 0.05 mm/s, the content of which in the treated effluent at this stage is 30-35% of the total mass, and the removal of residual oil products with a hydraulic particle size of 0.05 mm/s or more, which constitutes 10-15% of the total mass. Thus, after purification in the proposed device, the content of suspended solids will not exceed 5-7 mg/l, and oil products - 0.5-0.7 mg/l, with initial concentrations of up to 3000 mg/l for suspended solids and up to 300 mg/l for oil products.

The design of the thin-layer settling module 6 is a rectangular structure that includes a frame 19 consisting of four side walls, internally divided into separate layers by inclined parallel plates 18, which serve to remove the collected sediment of suspended substances and oil products. The inclined plates 18, united by the frame 19, are assembled into the thin-layer settling module 6. In the second chamber 16 of the housing 1, there is a partition 13 installed transversely to the direction of flow of the water being purified. The partition 13 is attached hermetically to the lower flange 9 and the walls of the second chamber of the housing 1 by the method of extrusion welding. The partition 13 is necessary for separating the purified effluent and the purified volume of water at the outlet of the thin-layer settling module 6. A rectangular opening for installing the thin-layer settling module 6 is made in the partition 13. The thin-layer settling module 6 is installed in the opening of the partition 13 and is secured hermetically by the method of extrusion welding. Module 6 for thin-layer settling is installed so that the plates are inclined at an angle of 35-70° relative to the horizontal. At a smaller angle, plates 18 become clogged, requiring frequent cleaning. At a greater angle, the sludge slides too quickly, which can cause undesirable effects (slurry formation and turbidity). Plates 18 are designed as shelves and are made of rigid sheet materials with a roughness not exceeding 0.01 mm. The thickness of plate 18 of module 6 for thin-layer settling is 5-8 mm, which, on the one hand, ensures the necessary rigidity and strength of the structure, and on the other hand, reduces the weight and dimensions of the thin-layer settling module 6.

The device is designed to purify rainwater from coarse impurities, remove suspended solids with medium and high hydraulic particle size of 0.05-2 mm/s, as well as large fractions of suspended solids (sand, etc.) with a hydraulic particle size of 2-5 mm/s) carried out of the main storm sewer networks by a strong flow of water, as well as undissolved petroleum products.

The proposed device operates as follows.

Before starting work, the first chamber 15 and the tangential sand trap 3 are filled with water to the level of the depressions of the comb spillway 4.

The raw flow of untreated rainwater is fed into the upper cylindrical section of tangential sand trap 3, installed in first chamber 15 of housing 1, through inlet pipe 14, through debris collection mesh 5, tangentially, resulting in flow vortexing. The tangential water inlet and the circular cross-section of tangential sand trap 3 create a helical flow, thereby increasing the distance the suspended particle travels within the structure of tangential sand trap 3, while simultaneously moving downward toward opening 17 for the passage of runoff and sediment. Coarse suspended solids and sand in the wastewater, moving along an elongated trajectory under the force of gravity, settle to the bottom of the first chamber 15, and the clarified flow, overflowing through the comb spillway 4, is diverted through the overflow pipe 11 into the second chamber 16 of the housing 1, where the thin-layer settling module 6 is installed. After settling for up to one minute, coarse sediment falls to the bottom of the first chamber 15, removed by the airlift system 7.

The flow of water through the opening 17 for the passage of runoff and sediment flows out of the conical part of the tangential sand trap 3 and enters the first chamber 15 of the body 1, which is a vertically installed section of a pipe of a round open cross-section, with a diameter exceeding the diameter of the tangential sand trap 3, with a hermetically secured partition 10.

The sediment accumulates in the first chamber 15, and the clarified water reaches the level of the comb-type spillway 4 and flows uniformly into the comb-type spillway 4. The water, now 85-90% free of coarse sand, fine suspended solids, and undissolved oil products, is then fed through the overflow pipe 11 to the next settling stage, the second chamber 16.

The use of a tangential sand trap 3 reduces the footprint of the unit during operation. The use of a comb-type weir 4 also improves the unit's compactness and allows for increased stormwater treatment during the settling stage without increasing the overall dimensions of the sand trap or the first chamber 15 of building 1.

After a settling time of 1 minute, coarse sediment with a hydraulic size of 0.1-5 mm/s settles to the bottom of the first chamber 15 and is subsequently removed. The diameter of the tangential sand trap 3 is individually calculated based on the stormwater flow rate so that the estimated settling time in the sand trap is at least 1 minute.

Due to the helical movement of the storm water flow, the length of the path of the purified liquid increases, while maintaining the compact dimensions of the sand trap.

Through pipe 11, the overflow of purified water is fed into the second chamber 16. A partition 13 is installed in the space of the second chamber 16, within the rectangular opening of which a thin-layer settling module 6 is rigidly and hermetically secured. Thin-layer settling module 6 is used for medium and deep purification of wastewater from suspended solids and petroleum products.

The incoming purified water fills the second chamber 16 and, rising upward, passes through thin-layer inclined plates 18 in a thin layer of water. Solid particles settle on them, coalesce into larger particles, and, growing in size, slide to the bottom, forming sediment. Thin-layer settling module 6 utilizes a countercurrent flow pattern for liquid and sediment: the upward direction of the purified water flow is counter-directional to the sliding direction of the sediment deposited on the surface of thin-layer settling module 6. Since the height of the liquid layer between thin-layer plates 18 is tens of times smaller than the depth of conventional settling tanks, the settling process is very rapid. Contaminant particles reach the surface of thin-layer plates 18 and, under the force of gravity, slide down it into sediment accumulation zones. A shallow liquid layer also ensures a more uniform temperature within the layer, minimizes the influence of density and convective currents on suspended solids settling, increases its hydrodynamic stability, and reduces flow turbulence. According to the theory of gravity settling, dividing the overall settling zone into a series of shallower elementary settling zones simultaneously increases the settling area and reduces the specific load of suspended solids on it, thereby ensuring more efficient liquid clarification and utilization of the settling tank's volume, the productivity of which increases proportionally to the settling area.

This design of module 6 allows for faster sedimentation of suspended solids, with the collected impurities flowing by gravity down the slope into the flocculation and sediment compaction zone. Oil products float to the surface of the water in the second chamber 16, in the space between partitions 11 and 13.

For stable operation of module 6 of the thin-layer module with the required efficiency, it is necessary to periodically regenerate the surface of the plates 18, that is, clean them from contaminants to improve sediment sliding.

Purified water, after passing through module 6 of thin-layer settling, accumulates in the second chamber 16 of body 1, in the space between partition 13 and the wall of the second chamber 16, and then, through outlet pipe 20, is fed to the next stage of purification.

Thus, due to the sequential arrangement of the tangential sand trap 3 and the thin-layer settling module 6, installed in one body of the proposed device, the process of separating impurities is intensified, which makes it possible to correspondingly reduce the dimensions of the settling structures and ensure a high liquid purification effect.

The sediment and oil product pumping system can be implemented, for example, with an airlift system. Airlift system 7 is powered by a single compressor, and airlifts 7 are activated automatically during rainfall using a float level sensor. In the first chamber 15, airlift 7 pumps sediment from the bottom, and in the second chamber 16, airlift 7 is configured to pump both sediment from the bottom and oil products from the surface of the treated water in the space of the second chamber 16 between partitions 11 and 13.

The design of the proposed device eliminates the need to use automated control systems for wastewater treatment processes.

Claims (3)

1. A device for the first stage of surface wastewater treatment, characterized in that it contains a housing with a partition dividing the housing into first and second chambers, in the space of the first chamber of the housing a tangential sand trap with a comb-type overflow drain is installed, and in the space of the second chamber a thin-layer settling module is installed, wherein the comb-type overflow drain of the tangential sand trap is equipped with an overflow branch passing through an opening in the partition dividing the housing into chambers. 2. The device according to paragraph 1, characterized in that a waste collection net is installed inside the tangential sand trap. 3. The device according to paragraph 1, characterized in that a partition is installed in the space of the second chamber of the housing for installing a thin-layer settling module.