ZA200210208B

ZA200210208B - Effluent purifying device.

Info

Publication number: ZA200210208B
Application number: ZA200210208A
Authority: ZA
Inventors: Bernard Beaulieu
Original assignee: Htci
Priority date: 2000-06-15
Filing date: 2002-12-17
Publication date: 2003-11-30
Also published as: JP2004503368A; US20040025961A1; FR2810310B1; CA2412487A1; EP1292542A1; MA26049A1; BR0111568A; AU2001267632A1; FR2810310A1; KR20030009539A; EA004018B1; WO2001096246A1; AP2002002686A0; EA200300022A1; CN1443139A

Description

Effluent purification plant

The subject of the present invention is a plant for the physico-chemical and bacteriological purification of water. - Most industrial effluents are currently discharged into purification stations in order to be treated and purified.

For this purpose, contracts are drawn up between industrial concerns that discharge effluents and water treatment companies.

The cost of treating this effluent may be very high for the industrial concerns and may in certain cases exceed the water consumption cost.

When the responsibility for effluent treatment is thus transferred back to the industrial concerns, it may be envisioned equipping the latter with their own means for treating spent effluents.

However, current plants for treatment spent effluents are poorly suited to treating spent effluents on the scale of an enterprise that discharges small volumes of water, compared with, for example, a local community.

This is because current plants comprise several elements which carry out the effluent homogenization, degreasing, coagulation and flocculation operations sequentially. These plants are expensive and take up a large area of ground.

For these reasons, it is difficult, for an industrial concern, to be equipped with its own installation for purifying its effluents.

. It is an object of the invention to provide an effluent treatment plant which takes up a small amount of space and has a low installation and operating cost, while still achieving a high degree of purification.

For this purpose, the effluent purification plant according to the invention includes: — - a clarification tank; - a pump delivering the effluent in a pulsed manner into a chamber placed on the upper face of the clarification tank; - at least one metering pump for adding an effluent coagulating or flocculating reactant into said chamber; and - a delivery pipe taking the effluent laden with reactants from said chamber into the bottom part of a flocculation vessel placed inside the clarification tank, in which vessel a sludge bed forms, the effluent flowing upward through said bed and being clarified in contact with the latter. :

By introducing the effluent into the base of the sludge bed, the aggregation of the organic and inorganic pollutants present in the effluent on the flocs constituting the sludge bed is maximized. In addition, the inflow of the effluent in a pulsed manner allows the flocs to be set in motion and increases their aggregation capability. This plant therefore allows very effective flocculation in a short time.

As a corollary, the consumption of chemical reactants is reduced because the flocculation process has been maximized.

The plant according to the invention achieves a BOD abatement of more than 70% and excellent filtration of metals.

One of the major criteria regarding pollution of an

. effluent is the BOD or biological oxygen demand, which is the oxygen consumption of the microorganisms present in the effluent in order to assimilate the organic substances in this effluent.

Particularly advantageously, the flocculation vessel comprises a frustoconical upper part extended by a — cylindrical lower part into which the pipe runs.

Because of this particularly advantageous configuration of the flocculation vessel, the effluent laden with reactants is introduced into a region whose volume is relatively restricted, namely the cylindrical part of the flocculation vessel. In this restricted volume, the flocculation is particularly intense.

Moreover, thanks to the inclined surface of the frustoconical part, the sludge formed by the accumulation of flocs may spill over from the flocculation vessel under the effect of an increase in the load.

The flocculation takes place dynamically and is self- regulated. This is because, whatever the load to which : 25 the plant is subjected, the flocculation always takes place optimally, on the one hand ensuring intense flocculation in the cylindrical part and, on the other part, spilling the excess sludge out of the flocculation vessel.

According to one particularly advantageous feature of the invention, the delivery pipe comprises a first tube, one of the ends of which runs into the chamber and the other end of which is provided with radial homogenizing openings above the surface of the frustoconical vessel and a second tube, of larger diameter than the diameter of the first tube, the upper end of which covers the circumferential homogenizing openings of the first tube and the lower end of which :

runs into the bottom part of the frustoconical vessel.

The configuration of the delivery pipe allows the effluent and the reactants to be homogeneously mixed before being introduced into the bottom part of the flocculation vessel. — Advantageously, the lower part of the clarification tank has a frustoconical part which receives the sludge spilling over the flocculation vessel and a pump extracts the sludge collected in the frustoconical part of the clarification vessel.

Thanks to the frustoconical shape of the lower part of the clarification tank, the sludge that spills out of the flocculation vessel is collected on a defined surface of the base of the clarification tank. This sludge can be easily extracted by a pump. Load variations may therefore be absorbed without any difficulty and the sludge bed is regulated autonomously.

Preferably, calibrated openings are provided in the upper part of the clarification tank so as to allow the clarified effluent to be poured into a storage tank surrounding the clarification tank.

The storage tank surrounds the clarification tank, thereby making it possible to obtain a particularly compact plant in which the ground space occupied is markedly less than the plants of the prior art.

Advantageously, the lower end of the delivery pipe has a divergent frustoconical section so as to improve the dispersion of the effluent in the sludge bed.

According to a preferred embodiment of the invention, a filter material is placed between the clarification tank and the storage tank, the clarified effluent

. flowing through said filter material before being stored in the bottom part of the storage tank.

According to an advantageous feature, the metering pumps introduce reactants into the bottom part of the mixture chamber, upstream of a static mixer placed on an effluent feed pipe, and into the bottom of the - cylindrical part of the flocculation vessel, respectively. The reactants are therefore introduced into the plant at points where their action is optimum.

According to advantageous features that the invention may have, the effluent clarification plant includes: - a filtration vessel containing a filter material placed between the chamber and the flocculation vessel; - a wall located between the flocculation vessel and the filtration vessel; and - a pipe, of larger diameter than the delivery pipe and coaxial with the latter, extending between the wall and the filtration vessel.

Preferably, the upper edge of the frustoconical part of the flocculation vessel is contiguous with the internal face of the tank.

Preferably, the filtration vessel has, on its lower face, openings protected by strainers allowing the filtered water to flow out.

The filter substance allows residual pollutants at the outlet of the clarification vessel to be reduced.

According to one particularly advantageous embodiment of the invention, a pump sucks the clarified effluent out of the storage tank and introduces it into at least one annular chamber, placed on the external face of the storage tank, containing a granulate that fixes bacteriological elements. ‘

The clarified effluent is set in motion in an annular chamber containing a granulate that fixes the bacteriological elements. The vortex flow undergone by the effluent in the annular chamber allows there to be remarkably good contact between the granulate and the effluent and consequently excellent and rapid fixing of _. the bacteria. The BOD abatement reaches more than 95%.

Preferably, the annular chambers are four in number, each communicating with the one adjacent thereto via a conduit.

Each of the annular chambers contains a granulate with the property of fixing specific bacteria, so that as the effluent passes in succession through the four chambers a remarkably good biological treatment is achieved.

Advantageously, a recovery pump sucks up the clarified effluent in the upper annular chamber and reinjects it into the lower chambers.

This recovery pump maintains a regular annular velocity of the effluent in which the granulate is in suspension.

Preferably, the storage tank, the clarification tank, the flocculation vessel and the annular chambers are made of plastic. ’ In order for the invention to be well understood, it will be described below with reference to the appended schematic drawing showing a preferred embodiment of the effluent clarification plant.

Figure 1 is a sectional view of the plant according to the invention.

= 7

Figure 2 shows the effluent purification plant according to the invention incorporated into a treatment installation.

Figure 3 shows an alternative embodiment of the invention, intended to deliver drinking water in isolated sites.

As the sectional view in figure 1 shows, the effluent purification plant comprises a cylindrical storage tank 1. A cylindrical clarification tank 2 is placed concentrically inside the tank 1. The clarification tank 2, in its upper part, has uniformly distributed calibrated circular openings 3 and, in its lower part, has a frustoconical section 4. The concentric tanks 1 and 2 are joined by an annular platform 5 on which a filter material 8 rests. The annular platform 5 is pierced by uniformly distributed openings 6. The openings 6 are each covered by a strainer 7.

A flocculation vessel 12 is placed inside the tank 2.

The vessel 12 consists of a frustoconical upper part 13 that has a downwardly decreasing cross section and is extended by a cylindrical lower part 14. The flocculation vessel 12 is provided, on its lower face, with feet 15 that rest on the bottom of the tank 2.

An extraction pipe 17 runs between the feet 15 of the flocculation vessel 12, a pump 18 doing the extraction.

A chamber 20 is placed on the upper face of the tank 2.

The chamber 20 is fed by a pump 21 with effluent to be treated.

A feed pipe 10 delivers the effluent to be treated into the chamber 20, the displacement to be made being performed by a pump 21.

The feed pipe enters the chamber 20 tangentially, in :

such a way that the effluent is introduced into the chamber tangentially with an antivortex effect.

A static mixer 11 is placed in the feed pipe upstream of the chamber 20.

Metering pumps 22, 23, 24 inject flocculating or — coagulating reactants into the bottom part of the chamber 20, into the feed pipe 10, upstream of the static mixer 11, and into the bottom of the cylindrical part of flocculation base 12, respectively.

A vertical delivery pipe 25 extends from the chamber 20 into the cylindrical part 14 of the flocculation vessel 12. The delivery pipe 25 comprises a first tube 26 that runs into a second tube 27 of larger diameter than the diameter of the tube 26. At its upper end, the tube 26 runs into the chamber 20 and its lower end is provided with radial openings 28. A hemispherical element 29 blocks off the lower end of the tube 26. The tube 27 covers the openings 28 of the tube 26 and extends down to the cylindrical part of the flocculation vessel 12.

On its outer face, the tank 1 receives four superposed annular chambers 31, 32, 33, 34.

Each chamber communicates with the chamber that is adjacent to it via a conduit 35.

A pump 36 is provided that takes in from the bottom of the tank 1 via a pipe 37 and discharges into the lower annular chamber 31.

A recovery pump 39 takes in from the upper annular chamber 34 and delivers into the two intermediate chambers 32 and 33.

An air circuit 38 introduces compressed air into each of the annular chambers 31, 32, 33 and 34 and into each ‘

of the strainers 7.

This introduction is performed by a compressor (not shown in the drawing). i

The annular chambers are each equipped with a manhole 41 allowing access to the inside of the chambers.

The upper annular chamber 34 extends up to the top of the storage tank 1 and is provided with an opening 43 that opens to the outside.

The operation of the plant described above is as follows: the effluent to be treated firstly undergoes a physico-chemical treatment and then a bacteriological treatment.

The effluent, coming from a storage region 45, is sucked up by the pump 21 and introduced into the chamber 20. A reactant is introduced into the effluent upstream of the static mixer, the latter ensuring that the effluent and the reactant are very rapidly mixed.

Suction of the effluent by the pump 21 takes place intermittently, for example 15 to 30 seconds of suction followed by a rest time of 15 to 60 seconds, so that the effluent is introduced into the chamber 20 in a pulsed manner. In the chamber 20, the pump 22 injects a coagulating or flocculating reactant into the effluent.

These reactants may be ferric chloride, aluminum sulfate or polymers and they depend on the type of effluent to be treated. The action of the pumps 22 and 23 corresponds to an effluent pulsation period.

Under the effect of the pulsed delivery by the pump 21, the effluent laden with reactants is flushed out of the chamber 20 and escapes via the vertical pipe 25.

The openings 28 made in the upper tube 26 of the pipe allow the effluent/reactant solution to be homogenized. :

At the bottom of the delivery pipe 25, the effluent is brought into contact with a sludge bed consisting of flocs. The flocs are put into suspension by the pulsations that set the effluent in motion. On contact with the flocs forming the sludge bed, the organic or inorganic pollutants aggregate on these flocs and as — the effluent gradually passes through the sludge bed it becomes clarified. Introduction of flocculating reactant by the pump 24 makes it possible to intensify the flocculation.

In the event of an increase in load, the excess sludge spills out of the flocculation vessel and collects at the center of the frustoconical part 4 of the clarification tank 2. It is extracted by the pump 18.

Since the clarified effluent has a lower density than the flocs forming the sludge bed, it spills out of the clarification tank via the openings 3 made in the latter.

The clarified effluent spills out into the lower part of the storage tank 1 which surrounds the clarification tank, flowing through the filter substance 8.

This filter substance may consist of particles of quartz, pozzolana, active carbon, diatomaceous earth or pumice stone and makes it possible to reduce the residual load of the effluent after clarification.

The filter substance may be washed by countercurrently introducing a water/air mixture via the nozzles 9. The introduction of this mixture takes place simultaneously with, and in equal volume as, extraction of the excess sludge by the pump 18 so as not to disturb the clarification dynamics.

At this point, the effluent has undergone a physico-

chemical treatment and is therefore clear. It is stored in the lower part of the storage tank.

The effluent is then sucked up by the pump 36 and, after air has been added, it is discharged tangentially into the annular chamber 31 so as to create a vortex inside this chamber. The chamber 31 contains a — granulate that fixes the bacteria present in the effluent. Inside the annular chamber, the granulate is put into suspension and agitated under the effect of the vortex flow. By putting this granulate into suspension and agitating it, the bacteriological pollutants present in the effluent are fixed remarkably well.

The pump 39 sucks up the effluent into the annular chambers 32, 33 and 34 that communicate via the conduits 35. It maintains a constant velocity in said annular chambers by reinjecting the effluent sucked up from the upper chamber 34 into the intermediate chambers 32 and 33. Each of the chambers 31, 32 and 33 contains a specific granulate (active carbon, sand or calibrated polystyrene beads) that acts on a specific bacterium in such a way that when the effluent is extracted from the annular chamber 34 via the opening 43 it has undergone a complete bacteriological treatment.

The effluent may undergo a subsequent treatment, for example an addition of disinfectant represented by the reference 45 in figure 2.

Figure 3 shows an embodiment of the invention intended for delivering drinking water in isolated sites.

The plant according to the invention is fed via a hand pump 50.

The tank 2 is divided by two horizontal walls 51 and 52

} that define an upper part 47, an intermediate part 48 and a lower part 49.

The upper part has a chamber 20 into which a pipe 25 runs via an opening made in the wall 52.

The delivery pipe 25 connects the chamber 20 to the _ flocculation vessel 12 located in the lower part of the tank 2.

The lower end of the pipe 25 has a divergent frustoconical section 57.

The flocculation vessel 12 rests on the bottom of the tank 2 and its frustoconical upper part 13 joins the internal wall of the tank 2.

The frustoconical part 13 of the flocculation vessel is pierced by overflow openings 55.

The wall 51 is pierced by a circular opening onto which a discharge pipe 56 concentric with the delivery pipe is connected. 25 The discharge pipe 56 has radial overflow openings 59 at its upper end and terminates in a filtration tank 60 filled with a filter material such as sand.

A pipe 66 allows the tank 60 to be filled with filter material. ’ The bottom of the filtration tank 60 is provided with openings 61 protected by strainers 62.

Each strainer 62 is provided with a cleaning nozzle 65 connected to the pump 50.

Each of the upper, intermediate and lower parts of the tank 2 is provided with a draining valve 61, 62, 63. :

The hand pump 50, thanks to a manual three-way valve 67, can suck up a fluid coming from a well 68 or coming from the intermediate part of the tank 2. By means of a - manual three-way valve 68, this pump delivers either into the upper part of the tank 2 or into a pipe 70 that feeds the cleaning nozzles 65.

The operation of this embodiment of the invention will now be described.

The valves 67 and 68 are set so as to suck up nonpotable water from a well 68 and deliver this water into the upper part of the tank 2. :

The water undergoes a settling operation and the particles are deposited on the wall 52.

A flocculating or coagulating reactant is introduced into the chamber 20 by a pump (not shown).

When a sufficient volume of water has been introduced into the upper part 47, the water spills out into the chamber 20 and then into the delivery pipe 25 that runs into the flocculation vessel 12.

At the bottom of the delivery pipe 25, the water is brought into contact with a sludge bed consisting of flocs. The divergent frustoconical section of the delivery pipe 25 allows excellent dispersion of the water in the sludge bed. The water is therefore clarified on contact with the fluidized sludge bed.

The excess sludge discharges from the flocculation vessel 12 through the openings 55 and spills out into the bottom of the tank 2. This sludge may be extracted via the valve 63.

Under the effect of the pulsed delivery by the pump 50, :

the clarified water escapes from the lower part 49 via the discharge pipe £6 and spills out via the openings 59 into the filtration tank 60.

Since the tank is filled with a filter material such as sand, the clarified water undergoes a filtration operation. The water leaves the tank 60 via the . openings 61 protected by the strainer 62 and is stored in the intermediate part 48.

The water may be withdrawn via the valve 62, in order to be consumed.

The water may also undergo a second clarification cycle by setting the valves 67 and 68 in such a way that the pump 60 sucks up, from the intermediate part 48, water that has undergone a first clarification cycle and delivers this water into the upper part 47 in order to undergo a further clarification cycle.

The valves 67 and 68 may also be set in such a way that water is sucked up from the intermediate part 49 and delivered via the pipe 70 into the cleaning nozzles 65.

The cleaning nozzles 65 open into the strainers 62 and the water sent countercurrently cleans the filter medium. During this operation, the valve 63 is open.

The invention thus provides a particularly compact effluent purification plant of low installation costs, while being capable of carrying out excellent physico- chemical and bacteriological purification.

It goes without saying that the invention is not limited to the embodiment described above by way of example; rather it encompasses all embodiment variants thereof. Thus, this purification plant may be installed in the form of a module that incorporates the electronics for controlling the various pumps and rests on a transportable platform.

Claims

1. An effluent purification plant comprising a clarification tank (2) characterized in that it includes: - a pump (21, 50) delivering the effluent in a — pulsed manner into a chamber (20) placed on the upper face of the clarification tank (2); - at least one metering pump (22, 23, 24) for adding an effluent coagulating or flocculating reactant; and - a pipe (25) taking the effluent laden with reactant (s) from said chamber into the bottom part of a flocculation vessel (12) placed inside the clarification tank, in which vessel a sludge bed forms, the effluent flowing upward through said bed and being clarified in contact with the latter.

2. The effluent purification plant as claimed in claim 1, characterized in that the flocculation vessel (12) comprises a frustoconical upper part (13) extended by a cylindrical lower part (14) into which the pipe (25) runs.

3. The effluent purification plant as claimed in claim 1 or claim 2, characterized in that the pipe (25) comprises a first tube (26), one of the ends of which runs into the chamber (20) and the other end of which is provided with radial homogenizing openings (28) and a second tube (27), of larger diameter than the diameter of the first tube (26), the upper end of which covers the homogenizing openings (28) of the first tube and the lower end of which runs into the bottom part of the frustoconical vessel (12). 4, The effluent purification plant as claimed in one of claims 1 to 3, characterized in that the lower part of the clarification tank (2) has a frustoconical part ’

(4) which receives the sludge spilling over the flocculation vessel.

5. The effluent purification plant as claimed in one of claims 1 to 4, characterized in that in that a pump (8) extracts the sludge collected in the frustoconical part of the clarification vessel.

6. The effluent purification plant as claimed in one of claims 1 to 5, characterized in that calibrated openings (3) are provided in the upper part of the clarification tank (2) so as to allow the clarified effluent to be poured into a storage tank surrounding the clarification tank (2).

7. The effluent purification plant as claimed in one of claims 1 to 6, characterized in that the lower end of the delivery pipe (25) has a divergent frustoconical section.

8. The effluent purification plant as claimed in one of claims 1 to 7, characterized in that a filter material (8) is placed between the clarification tank (2) and the storage tank (1), the clarified effluent flowing through said filter material before being stored in the bottom part of the storage tank (1).

9. The effluent purification plant as claimed in one of claims 1 to 8, characterized in that the metering pumps (22, 23, 24) introduce reactants into the bottom part of the chamber (2), upstream of a static mixer (11) placed on an effluent feed pipe (10), and into the bottom of the cylindrical part of the flocculation vessel, respectively.

10. The effluent purification plant as claimed in one of claims 1 to 9, characterized in that it includes: - a filtration vessel (60) containing a filter material placed between the chamber (20) and the :

flocculation vessel (12); - a wall (51) located between the flocculation vessel (12) and the filtration vessel (20); and - a discharge pipe (56), of larger diameter than the delivery pipe (25) and coaxial with the latter, extending between the wall (51) and the filtration vessel (20).

11. The effluent purification plant as claimed in claim 10, characterized in that the upper edge of the frustoconical part (13) of the flocculation vessel (12) is contiguous with the internal face of the tank (2).

12. The effluent purification plant as claimed in claim 10 or «claim 11, characterized in that the filtration vessel (60) has, on its lower face, openings (61) protected by strainers (62) allowing the filtered water to flow out.

13. The effluent purification plant as claimed in one of claims 1 to 12, characterized in that a pump (36) sucks the clarified effluent out of the storage tank (1) and introduces it into at least one annular chamber (31), placed on the external face of the storage tank, containing a granulate that fixes bacteriological elements.

14. The effluent purification plant as claimed in claim 13, characterized in that the annular chambers are four in number (31, 32, 33, 34), each communicating with the one adjacent thereto via a conduit (35).

15. The effluent purification plant as claimed in either of claims 13 and 14, characterized in that a recovery pump (39) sucks up the clarified effluent in the upper annular chamber (34) and reinjects it into the lower chambers (31, 32, 33).

16. The effluent purification plant as claimed in either of claims 1 and 15, characterized in that the storage tank (1), the «clarification tank (2), the flocculation vessel (12) and the annular chambers are made of plastic.