EP4719633A1 - Clarifier with concentric stacked cones - Google Patents

Abstract

Clarifier (100) for clarifying liquid in a reactor, which comprising an outer vessel (6) fixed to the reactor, intake pipes (12) fluidically connected to the reactor with the inside of the outer vessel (6), effluent weir (8) placed on the inner perimeter of the outer vessel (6) on the top, characterised in that it further comprising top cone (1), bottom cone (3) and stacked cones (2) with a central cavity for sludge elimination and placed on top of each other between the top cone (1) and the bottom cone (3) with spacers, internal pipes (11) fluidically connected to the intake pipes (12) and stacked cones (2) with distribution units (7), sludge discharger placed in the bottom cone (3) to discharge sludge.

Description

Clarifier with Concentric Stacked Cones

The field of the invention

The object of the present invention relates to cone clarifiers, especially concentric stacked-cone clarifiers.

The state of the art

A vast majority of municipal or sanitary wastewater treatment systems, and a large portion of industrial or agricultural wastewater treatment systems, consist of two main processes:

• a biological treatment process (such as activated sludge processes, moving bed biofilm reactors, fixed film reactors, etc.) designed to remove or transform soluble components in the influent stream, followed by

• a solids separation stage (such as clarifiers, media or membrane filters, dissolved air flotation, etc.) designed to remove particulate components from the effluent of the biological process, allowing discharge of clarified effluent and removal of a stream of the separated solids, or the sludge .

The most commonly used unit for solids separation after a biological process is the clarifier. Essentially, this is a unit designed to reduce the flow velocity of the liquid to a point where the settling velocity of the particles settling out of the liquid is greater than the velocity of the movement of the liquid out of the vessel, thereby allowing the solids to settle to the bottom of the vessel within the period of time the liquid is retained in the clarifier. Clarifiers may be rectangular or round, and usually consist of an influent flow distribution mechanism, an effluent collection system, and a sludge conveyance system for collecting and removing the solids accumulated on the bottom of the clarifier. The main design parameter used for designing of clarifiers is the surface area of the clarifier, which is used to calculate both the hydraulic loading rate, and the solids loading rate. Due to the low liquid velocities required, clarifiers usually occupy a large area in the wastewater treatment plant, and construction and installation of these units have a significant impact on capital investments.

A known modification of the conventional clarifiers is an inclined plate clarifier (also known as lamella clarifier) which utilize a series of parallel inclined plates to increase the efficiency of the clarification process. By adding specifically designed, parallel plates in the clarification unit, the sedimentation surface area is increased, and as a result the capacity of the separation unit can be significantly increased without the need to increase the physical surface area of the clarifier. Inclined plate clarifiers, like convention clarifiers, are installed or constructed as a separate process unit located downstream of the biological treatment unit. The US4921609 A patent document describes a lamella clarifier. The disadvantage of these clarifiers that these are installed or built during the construction of the wastewater treatment plant as a separate unit, downstream of the biological unit treatment unit.

As a consequence of the above there is a requirement for a clarifier with small footprint and increased sedimentation surface. Additionally, it should be possible to install or build the clarifier inside of existing wastewater treatment plants to decrease the time and cost of the process. Brief description of the invention

The present invention is based on the recognition that clari fiers with increased area surface and with the gradual slowing of water velocity and center- feed radial flow are highly ef ficient .

In accordance with the description above , the present invention relates to a clari fier for clari fying liquid in a reactor, which comprising an outer vessel fixed to the reactor, intake pipes fluidically connecting the reactor liquid with the inside of the outer vessel , ef fluent weir placed on the inner perimeter of the outer vessel on the top, characterised in that it further comprising top cone , bottom cone and stacked cones with a central cavity for sludge elimination and placed on top of each other between the top cone and the bottom cone with spacers , internal pipes fluidically connected to the intake pipes and stacked cones with distribution units , sludge discharger placed in the bottom cone to discharge sludge .

The preferred embodiments of the present invention are determined in the subclaims .

The figures

Figure 1 shows the side view of the clari fier according to the invention;

Figure 2 shows the top cone of the clari fier with the pipes in perspective view;

Figure 3 shows the side view of an embodiment of the distribution unit according to the invention; Figure 4 shows the side view of another embodiment of the distribution unit according to the invention;

Figure 5a-5b shows the side and top view of another embodiment of the distribution unit according to the invention;

Figure 6 shows the side view of an embodiment of the stacked cones with pipes according to the invention;

Figure 7 shows the side view of another embodiment of the stacked cones with pipes according to the invention;

Figure 8 shows the side view of another embodiment of the stacked cones with pipes according to the invention;

Figure 9 shows the perspective top view of the top cone with the outer vessel .

Detailed description of the invention

The essence of the apparatus according to the invention is that the clari fier comprising stacked cones with central cavity to separate and discharge solid particles from the liquid and internal pipes with distribution units to distribute liquid .

Figure 1 shows the side view of the clari fier 100 and the cross section of it . The clari fier 100 comprising a top cone 1 for intake and flocculation, stacked cones 2 for settling and bottom cone 3 for sludge collection and discharge . The clari fier 100 further comprising sludge discharger mixer or pump (not shown) , support structure 5 and outer vessel 6 .

Figure 2 shows the top cone 1 of the clari fier 100 from inside . The clari fier 100 comprising a series of stacked cones 2 ( figure 6- 8 ) , properly spaced vertically and connected with a series of internal pipes 11 . All of the vertically stacked cones 2 are installed within the outer vessel 6 or sealed sleeve , which segregates them from the liquid outside the outer vessel 6 . The entire clari fier 100 is installed submerged within a biological reactor, either standing on a support structure 5 connected to the floor of the reactor or suspended from beams above the reactor, so that in essence the unit is almost entirely under water .

The stacked cones 2 are the basic, repeating unit of the clari fier 100 . They are conical units with an inclination of at least 55 degrees . The upper diameter of the stacked cones 2 is between 1 and 3 m, the lower diameter between 0 . 2 and 0 . 75 m . The material of the stacked cones 2 can be any type of plastic, fibreglass or stainless steel .

Stacked cones 2 are placed the top of each other between the top cone 1 and the bottom cone 3 with spacers to maintain a preferred distance vertically . The top cone 1 is the first stacked cone 2 from the liquid level , and the bottom cone 3 is the last stacked cone 2 based on the liquid level . The clari fier 100 usually comprising between four to twenty stacked cones 2 , identical in dimensions to the top cone 1 .

The stacked cones 2 are assembled at a fixed vertical distance from one another, 5 to 25 cm, typically 10 cm apart .

Separation may be maintained by vertical spacers or any other mechanical means .

Figure 3-5b shows the di f ferent embodiment of the distribution of the liquid in the stacked cones 2 . Figure 3 shows the embodiment , where each stacked cone 2 is equipped with preferably three-six distribution units 7 , which are part of the internal pipes 11 . These distribution units 7 are forming distribution vents and are part of the internal pipes 11 where liquid entering from the internal pipes 11 to the stacked cones 2 . The liquid is introduced to the bottom of the stacked cones 2 and distributed along the top of the gap between the stacked cones 2 . Figure 4 shows another embodiment , where the distribution units 7 forming a distribution cone attached to the stacked cone 2 and to the internal pipes 11 . This distribution cone distributes the liquid from the internal pipes 11 evenly in the stacked cone 2 . Figure 5a-5b shows another embodiment from the side and top view, where the distribution unit 7 is a tapered distribution cone , and only one internal pipe 11 distribute the liquid from the reactor to these tapered distribution cones .

The outer vessel 6 is an outer container, which purpose is to separate the clari fier 100 from the outside liquid in the reactor . The outer vessel 6 can be a single cylindrical unit , 3-5 metres high, or perhaps made up of separate segments for ease of transport and installation . We do not exclude that the outer vessel 6 may have other shapes on the outside , but the inside of the outer vessel 6 must be similar to the stacked cones 2 upper structure with a larger diameter .

The clari fication process starts in the clari fier 100 with the intake of the uncleaned liquid from the reactor . Figure 2 shows one embodiment , where dedicated piping allows liquid into the top cone 1 of the clari fier 100 in a controlled fashion . Due to the centripetal motions of the liquid bringing the particles into contact with one another, it undergoes coagulation/ flocculation, and internal pipes 11 leads liquid downward and distributes it within the stacked cones 2 . With this embodiment the liquid from the reactor traverse both the wall of the stacked cone 2 and the outer vessel 6 in tangentially-inserted intake pipes 12 , thereby these intake pipes 12 connecting the body of water in the reactor with the top cone 1 , allowing water to flow inwards . Liquid can exit the top cone 1 through internal pipes 11 which may be located at di f ferent height within the top cone 1 , and conveying the liquid down to each of the stacked cones 2 . Preferably, the top cone 1 comprising three-six intake pipes 12 and one- five internal pipes 11 .

Figure 6 shows an alternative embodiment , where liquid from the reactor is introduced directly into the internal pipes 11 from multiple intake pipes 12 which may be located at di f ferent locations along the vertical axis .

Figure 7 shows an alternative embodiment , where liquid from the reactor enters a single internal pipe 11 from an intake pipe 12 from the top, bottom or side of the internal pipe 11 , and feeds into multiple tapered distribution units 7 to reach the individual stacked cones 2 .

Figure 8 shows an alternative embodiment , where liquid may be introduced into each of the stacked cones 2 individually, from 4- 8 slanted ducts as internal pipes 11 . These ducts may be fed by a single or multiple intake pipes 12 , which may be located between the stacked cones 2 and the outer vessel 6 . Sludge settled in the di f ferent stacked cones 2 slides down the inclined plates and is conveyed to the central cavity . Once in the central cavity, the sludge flows downward gravitationally toward the sludge mixer or pump, which discharges it downward and out of the clari fier 100 , either back into the reactor or to a separate sludge collection vessel .

The liquid travels upward because the top surface of the liquid inside the unit ( the level of the ef fluent weir 8 ) is lower than the liquid outside the unit ( in the bulk liquid) , so there is a driving force pushing the water from the intake (=bulk liquid) to the exit (=ef fluent weir 8 ) . The liquid from the ef fluent weir 8 introduced to a second reactor or a container with a lower liquid level than in the clari fier 100 . As the liquid travels up the inclined plates , sludge settles as described above , and the now-clari fied liquid travels upward and outward to the upper edge of the stacked cone 2 . Clari fied ef fluent collects in the space between the outer edge of the stacked cones 2 and the outer vessel 6 , and flows upward toward an ef fluent weir 8 ( shown in figure 9 ) located at the top of the outer vessel 6 on its inner side . From there the clari fied ef fluent is conveyed downstream, out of the reactor .

The bottom cone 3 as the sludge collection and discharge unit comprising a mixer or a pump . The mixer may be any type of vertical-shaft mixer with the shaft running through central cavity of the system, or a pump ( either submersible or otherwise ) installed in such a manner that the pump' s suction is applied to the bottom of the sludge collection and discharge zone . The pump or mixer create a downward flow of sludge thereby ef ficiently removing solids that are separated within the stacked cone 2 while preventing inflow of liquid from the surrounding reactor .

The clari fiers 100 are located within the biological reactor . The number and si ze of clari fiers 100 are defined by the flow of the system, the expected influent Total Suspended Solids ( TSS ) concentration, and the desired degree of clari fication . Clari fiers 100 may be anchored to the floor utili zing a steel support structure 5 , or may be suspended/attached to wall or beams .

Upon final installation, the clari fier 100 is almost fully submerged in the liquid of the surrounding reactor, with freeboard of 10-40 cm above the maximum water level separating the external liquid from the liquid inside the clari fier 100 . I f the clari fier 100 is equipped with a mixer, provisions are made for installation of the mixer motor above the clari fier 100 . In case a pump is used, location, type and related piping are determined case by case . Clari fied ef fluent is discharged from the clari fier 100 through to a pipe or an open channel designed to convey the clari fied liquid downstream to following process units .

In the clari fication process liquid from the reactor in which the clari fier 100 is submerged enters in the clari fier 100 via the tangentially installed intake pipes 12 . These intake pipes 12 have an opening outside the clari fier 100 , in the surrounding reactor liquid, they traverse the outer vessel 6 of the clari fier 100 , as well as the top cone 1 inclined surface , and discharge the incoming liquid into the top cone 1 .

Due to the tangential direction of the intake pipes 12 , the incoming liquid travels along the inclined surface , creating a rotational movement in the top cone 1 ; this movement serves to mix the incoming particles and increase contact between them, encouraging flocculation - formation of larger particle agglomerates that settle faster .

The flocculated liquid then leaves the top cone 1 through one or a number of di f ferent vertical internal pipes 11 . The internal pipes 11 may be located at di f ferent heights within the top cone 1 , in order to convey di f ferent fractions of the water in the top cone 1 (water at the top of the top cone 1 will contain less TSS than water at the bottom of the top cone 1 ) . Generally speaking, the intake to the internal pipes 11 may be located at the very bottom of the top cone 1 , through the central internal pipe 11 or at top internal pipes 11 , located at di f ferent heights within the top cone 1 . Exact location of the discharge depends on the results desired .

The internal pipes 11 conveying the liquid downward are equipped with accurately si zed and located distribution units 7 , in the gaps between the stacked cones 2 . These distribution units 7 are designed to distribute the liquid uniformly between the stacked cones 2 , and also to ensure their flow direction within the stacked cone 2 maximi zes utili zation of the stacked cone 2 surface and minimi zes disturbance to the sludge settling on the stacked cones 2 .

Alternatively, liquid may be fed into the clari fier 100 from multiple intake pipes 12 on the side of the outer vessel 6 , or through a single central intake pipe 12 , or through a single or multiple vertical intake pipe 12 located between the stacked cones 2 and the outer vessel 6 , or outside the outer vessel 6 .

Depending on the chosen liquid intake method, the liquid is distributed evenly throughout the entire lower circumference of the stacked cone 2 .

As liquid travels upward toward the upper edge of the stacked cone 2 , solids entrained in the liquid settle out and accumulate on the inclined floor of the stacked cone 2 , leaving increasingly clear liquid to travel upward and outward .

The sludge that settles on the inclined surface of the stacked cone 2 slides downward and inward, toward the open ( truncated) bottom of the stacked cone 2 . The floor angle , preferably 55 degrees , is calculated to ensure sludge does not stay stuck on the surface , but rather travels downward . As the sludge slides downward it sweeps and concentrates the solids , and when the sludge reaches the lower rim of the stacked cone 2 , it falls of f , into the vertical hollow shaft ( created by the stacked bottom openings of the stacked cones 2 . At the bottom of the central shaft is located a suction element , either a vertical mixer or a pump intake , which creates continuous downward movement of the sludge slurry downward toward the bottom opening, either to be discharged back into the main reactor body, or to be conveyed by a pump to a di f ferent location .

The clari fied ef fluent traveling upward along the inclined stacked cones 2 is discharged at the upper " lip" of the stacked cone 2 outward, into the gap between the outer perimeter of the stacked cones 2 and the surrounding outer vessel 6 . This "ef fluent up- flow channel" conveys the liquid upward toward an ef fluent weir 8 located at the top of the inner perimeter of the outer vessel 6 . Ef fluent collected in this ef fluent weir 8 exits the unit through a pipe or conduit to downstream units as required .

Industrial applicability

The clari fier can be placed at the end of any type of biological reactor, whether it is any variation of the activated sludge process , any biofilm process such as fixed media, MBBR, etc, and any hybrid system such as TEAS . The clari fier replaces the final clari fiers utili zing a smaller footprint , less mechanical and civil installations are required, and overall costs are reduced .

The clari fier is applicable in Activated Sludge process intensi fication . This is a relatively new field of development in the world of wastewater treatment , originating following the full scale commerciali zation of the Aerobic Granular Sludge process . Research from 2016 onward has been focusing on processes which allow separation of activated sludge according to particle density and si ze , in order to accumulate granular, well-settling sludge inside the biological system while wasting out lighter, less settleable material . This enhances biological treatment capacity as well as improving solids- separation capabilities , requiring smaller clari fiers , etc . Currently, process intensi fication is being explored with two main technologies - hydrocyclones and fine-pore sieves - in order to allow continuous separation of heavy sludge from lighter sludge , in order to select for the heavier material . The proposed solid separation system, by definition, could easily achieve the same aim; by locating it in any of a number of locations within the treatment process reactors , and designing it to a di f ferent (higher ) loading rate, it can easily be si zed to segregate heavy from light sludge , thereby achieving the exact same goal as a hydrocyclone . Intensi fication of a process utili zing this unit can bring on the positive outcomes of other intensi fication systems .

The clari fier further is applicable in attached-growth (biofilm system) system, as opposed to the various activated sludge processes which are all suspended-growth (MLSS-based) systems . The key di f ference is that in attached growth systems the active biomass is attached to a media and therefore immobili zed to one location, while suspended-growth biomass is free- floating in the liquid and travels freely throughout the entire system . Each of the two types of biomasses exhibit certain advantages and disadvantages in the treatment process ; to date , the main way of utili zing the advantages of both systems has been to integrate them into a hybrid system, Integrated Fixed- film Activated Sludge ( T EAS ) , which is a commonly used system . However, it has been identi fied that there are a number of applications and process requirements where rather than having the two systems completely combined as in I FAS , they need to be completely segregated - the suspended-growth (MLSS ) systems preceding the biofilm system . This is normally not done as it would require a full clari fication system after the suspended growth system and before the attached-growth system, which would make the system prohibitively expensive and uncompetitive . But with this clari fier with the stacked cone system the segregation of the suspended-growth systems and the biofilm systems is possible .

The advantage of the solution according to the invention is that it describes a clari fier, which is ef ficient and smaller than regular clari fiers . Further, this clari fier can be installed in an existing reactor and in various systems .

Claims

Claims

1. Clarifier (100) for clarifying liquid in a reactor, which comprising an outer vessel (6) fixed to the reactor, intake pipes (12) fluidically connected to the reactor with the inside of the outer vessel (6) , effluent weir (8) placed on the inner perimeter of the outer vessel (6) on the top, characterised in that it further comprising top cone (1) , bottom cone (3) and stacked cones (2) with a central cavity for sludge elimination and placed on top of each other between the top cone (1) and the bottom cone (3) with spacers, internal pipes (11) fluidically connected to the intake pipes (12) and stacked cones (2) with distribution units (7) , sludge discharger placed in the bottom cone (3) to discharge sludge.

2. Clarifier (100) according to claim 1, wherein the distribution unit (7) is distribution vent and preferably every stacked cone (2) comprising 3-6 distribution vents.

3. Clarifier (100) according to claim 1, wherein the distribution unit (7) is a distribution cone.

4. Clarifier (100) according to claim 1, wherein the distribution unit (7) is a tapered cone.

5. Clarifier (100) according to any of claims 1 to 4, wherein intake pipes (12) fluidically connected to the reactor outside the outer vessel (6) and to the top cone (1) to introduce liquid to the top cone (1) , and internal pipes (11) fluidically connected to the top cone (1) and the stacked cones (2) with distribution units (7) to introduce liquid to the stacked cones (2) , intake pipes (12) are placed tangentially to the top cone (1) to rotate the liquid introduced to the top cone (1) .

6. Clarifier (100) according to claim 5, wherein internal pipes (11) openings are located in different heights in the top cone ( 1 ) .

7. Clarifier (100) according to any of claims 1 to 4, wherein intake pipes (12) fluidically connected to the reactor outside the outer vessel (6) and to the internal pipes (11) to introduce liquid to the internal pipes (11) , and internal pipes (11) fluidically connected to the stacked cones (2) with distribution units (7) to introduce liquid to the stacked cones ( 2 ) .

8. Clarifier (100) according to any of claims 1 to 4, wherein the clarifier (100) comprising one intake pipe (12) and one internal pipe (11) , wherein the intake pipe (12) fluidically connected to the reactor outside the outer vessel (6) and to the internal pipe (11) to introduce liquid to the internal pipe (11) , and the internal pipe (11) fluidically connected to each stacked cones (2) with tapered cones to introduce liquid to the stacked cones (2) .

9. Clarifier (100) according to any of claims 1 to 4, wherein intake pipes (12) fluidically connected to the reactor outside the outer vessel (6) and to the internal pipes (11) to introduce liquid to the internal pipes (11) , the intake pipes (12) are placed vertically between the outer vessel (6) surface and the stacked cones (2) and internal pipes (11) are slanted ducts fluidically connected to stacked cones (2) with distribution unit (7) to introduce liquid to the stacked cones (2) , wherein the intake pipes (12) number is equal to the internal pipes (11) connected to a stacked cone (2) .