FR2583406A1 - Biological purifier with a membrane of the downward flow type for the biological treatment of sewage - Google Patents

Abstract

Biological purifier with a membrane of the downward flow type. The purifier comprises a purification container 23 filled with a filter medium 22, an aerator 24 provided in the purification container in order to introduce oxygen into it, a chamber 25a for collecting the biologically treated water, a water pipe 26 connected to the collecting chamber 25a, an air lift device comprising an air lift pipe 27 arranged vertically through the purification container in order to draw into the air lift pipe, at the bottom of the latter, the filter medium to which solid substances have adhered as a result of the biological treatment of the water and to lift the filter medium and the solid substances together while separating the solid substances from the filter medium, a device 29 provided at the top of the air lift pipe for separating the solid substances from the filter medium, a device 29 provided at the top of the air lift pipe for separating the solid substances from the filter medium and returning the filter medium to the purification container, and a pipe 30 for removing the solid substances from the separating device.

Description

Flow type rmiemorane biological scrubber

down.

  The invention relates to a biological membrane purifier of the downflow type which continuously performs both the biological treatment

  waste water as cleaning the filter material.

  A process is known which uses microorganisms

  to purify water polluted by organic matter.

  Various types of apparatus are known for implementing this method. One of them is a biological membrane purifier in which the impurities of the waste water are brought into contact with microorganisms adhering to solid particles so that the water can be purified by aerobic digestion. An apparatus of this type is a downward flow apparatus through which

  the waste water is caused to flow down.

  The membrane type biological scrubber

  lement down is a product of recent development and is constructed as shown as an example on the

figure 11.

  The apparatus shown in Figure 11 includes a reactor 1 which is divided by a floor plate 2 into a water treatment chamber 3 located above the floor plate 2 and a collecting chamber 5 located below. The water treatment chamber 3 is filled with a filtering material 4 such as anthracite, activated carbon or a light aggregate having for example a particle diameter of 2 to 10 mm. The collecting chamber 5 is designed to collect the water which has been biologically treated in the water treatment chamber 3. The floor plate 2 is provided with a water screen 6 through which the water treated in the chamber 3 is brought to the collecting chamber 5. The water treatment chamber 3 has an aerator 8 through which the air necessary for the biological treatment of the water is

  injected into the water by a ventilation fan 7.

  -2- The device also includes a reservoir 9 which is provided

  separately from reactor 1 to collect the treated water.

  A pipe 10 extends from the reactor 1 to the tank 9 for transferring to the latter the treated water from the collecting chamber 5. A retrograde purification pump 11, a retrograde purification fan 12 and a siphon 13 are provided respectively for the reservoir 9, the collecting chamber 5 and the water treatment chamber 3, for cleaning the filtering material 4 of the substances

solid mistletoe stuck to it.

  The water to be treated is introduced into the water treatment chamber 3 at the top thereof and subjected to biological treatment when it flows downward through the filtering material 4 and the water thus treated is collected. in the collecting chamber 5 through the screen 6. The water collected in the collecting chamber 5 is transferred to the reservoir 9 by the pipe 10 before subsequent use. The water passing through the filtering material 4 in the water treatment chamber 3 is purified by the microorganisms adhering to the surface of the filtering material 4. The constituents SS and BOD that the water contains adhere to

  the surface of the filter material 4 as a result of the treatment

  biologically and these solid substances collect on the filter material 4. They clog the pores of the filter material and increase resistance to

  the flow of water through. Retro cleaning

  grade of filter material 4 is carried out to remove these solid substances. A large amount of air is injected by the retrograde cleaning fan 12 into the water treatment chamber 3 to

  through the collecting chamber to separate the subs-

  solid tances of the filter material 4. Then, the retrograde cleaning pump 11 is driven to bring the treated water from the reservoir 9 to the water treatment chamber 3 to raise the solid substances to the treatment chamber. water 3 so that they cannot be pushed out of reactor 1 through

the siphon 13.

  However, the apparatus described above has some drawbacks. First of all, the device cannot be used to purify waste water as long as the filter material is cleaned 4. The purification of the water and the cleaning of the filter material 4 cannot be carried out. 'perform separately. So the device has a low operating speed. If it is desirable to carry out the cleaning of the filtering material 4 without interrupting the water purification operation, it is necessary to use several units of purifiers, which can make the whole system undesirably large . Secondly, no cleaning of the filter material 4 takes place as long as the apparatus is used to purify the water. An increasing quantity of solid substances adheres to the filter material 4 and

  decreases its purification efficiency by bio- treatment

  logic with the passage of time after matter

filter 4 has been cleaned.

  Thirdly, a large amount of air and a large amount of water are required for the retrograde cleaning of the filter material 4 and this requires

  so the fan 12, the pump 11 and a large tank

see 9.

  Fourth, the low purification yield by biological treatment means that a large

  amount of filter material 4 and retro-cleaning

  grade of filter material 4 also requires collecting chamber 5. The need for a large quantity of filter material 4 and of the collecting chamber

  makes reactor 1 undesirably large.

  In order to overcome the disadvantages indicated

  above, an object of the invention is to provide a purifying

  biological membrane membrane which can simulate

  the biological treatment of wastewater and the - 4 -

  cleaning of the filter material without any interruption

  tion and therefore has an improved water purification yield and which comprises only a small reactor, since it requires neither a fan, nor a retrograde cleaning pump, nor a large tank for collecting

purified water.

  The object of the invention is achieved by an apparatus comprising a purification container filled with a filtering material, an aerator provided in the purification container for bringing oxygen there, a chamber for collecting treated water. biologically, a water hose connected to the collecting chamber, an air lifting device comprising an air lifting tube arranged vertically through the purification container to suck in the air lifting tube, at the bottom of this, the filter material to which solid substances have adhered as a result of the biological treatment of water and lift together the filter material and the solid substances while separating the solid substances from the filter material, a device provided at the top of the tube air lift to separate the solids from the filter material and return the filter material to the scrubber, and a hose to remove the solids from the device

of seperation.

  The invention will now be described more precisely with reference to the drawings, in which: FIG. 1 shows a biological scrubber with

  membrane of the downward flow type according to a

  mier mode of execution of the invention; Figure 2 is a sectional view along line A - A of Figure 1; FIG. 3 represents a device for the treatment of retrograde cleaning waste which has been discharged by the purifier; Figure 4 shows a downflow membrane purifier according to a second embodiment; FIG. 5 is a sectional view of an alternative embodiment of the connection of the water pipe to the collecting chamber; Figure 6 is a sectional view of an alternative embodiment of the water collecting chamber; FIG. 7 represents a purification container according to another embodiment. FIGS. 8 and 9 show views in longitudinal and transverse section of an integrated assembly of air intake pipe and lifting tube; FIG. 10 is a view in longitudinal section of another example of an integrated assembly of air supply pipe and lifting tube, and FIG. 11 shows a biological purifier with

membrane according to a known type.

  With reference to FIGS. 1 and 2, the purifier 21 comprises a purification container 23 filled with a filtering material 22, an aerator 24 provided in the purification container 23 for supplying oxygen therein, a collecting chamber d water 25 for collecting the biologically treated water, a water pipe 26 connected to the water collecting chamber 25, an air lifting device 28 comprising an air lifting tube 27 arranged vertically through the container d purification 23 to suck in the bottom 27a of this tube the filter material 22 to which solid substances have adhered as a result of the biological treatment of waste water and lift together the filter material 22 and the solid substances while separating the solid substances from the filtering material 22, a separating device 29 provided at the top 27b of the air lifting tube 27 for separating the solid substances from the material

  filter 22 and bring the filter material 22 to the container

  wastewater treatment plant 23, and a drainage pipe 30 for

  remove the solid substances from the separating device 29.

  The filter material 22 can be chosen for example between anthracite, activated carbon and a light aggregate

_- 6 _-

  and for example have a particle diameter of 2 to mm. It forms a filtration layer 22a in the purification container 23. The latter has a conical lower part 23a in which the filtering material 22 collects effectively, so that it can be completely sucked continuously into the lifting tube. of air. The collecting chamber 25 is an integral part of the air lifting tube 27 and surrounds its lower end part. It is defined by a bowl-shaped container having an opening 25a. The water hose 26, which is connected to the

  collecting chamber 25 at one end, extends outside

  laughter of the purification container 23 through the wall of its lower part 23a. The purified water collected in the collecting chamber 25 is caused to flow upwards into a reservoir 31 by a difference in the level of water between the collecting chamber 25 and the

tank 31.

  The aerator 24 is located above the collecting chamber 25 so that oxygen can be uniformly supplied to the filter material 22 to allow the development of microorganisms on its surface. The bottom 27a of the air lifting tube 27 is located in the lower part 23a of the purification container 23 and its top 27b is disposed above the purification container 23. An air supply pipe 28a is bound

  to the air lifting tube 27, practically perpendicular

  culially to the latter, near its bottom 27a to bring air to the tube 27. The separator device 29 comprises a hollow frustoconical structure 29a having a conical wall surface 29c defined for example by

  a split or perforated plate or a network of metal wires-

  liquids having a mesh size which does not allow the filtering material to pass through 22. It also includes a protective element 29b which causes the filtering material 22 and the solid substances to fall onto the conical wall surface 29c of the hollow structure 29a. The protective member 29b has a hollow cylindrical shape which is easy to inspect for maintenance. The solid substances which have been separated from the filter material 22 are discharged through the pipe 30 with a small amount of purified water. The quantity of solid substances which are discharged can be regulated, for example by regulating the quantity of air supplied by the air supply pipe 28a, by varying the surface of the perforated plate or of the network in the separating device 29

  or by providing a valve in the discharge pipe 30.

  The operation of the apparatus is described below

described above.

  Air is supplied by the aerator 24 to the filter material 22 in the purification container 23 and causes the development of microorganisms on the surfaces of the

  particles of which the filter material 22 is composed.

  The SS and BOD constituents in wastewater are

  decomposed by oxidation as a result of the biolo-

  aerobic activity by the microorganisms and the solid substances which result therefrom adhere to the surfaces of the filtering material 22. The solid substances of the waste water and the solid substances formed by this biological treatment collect on the surfaces of the filtering material 22 or are retained by its particles. They move downward through the filtering layer 22a and are brought to the separating device 29 by the air lifting tube 27. Therefore, the water purified by the apparatus of the invention is practically free of all these substances solids, eliminating the need

  a settling tank which is usually necessary

  to occur in a process based on catalytic oxidation, using an activated sludge or comprising a sprinkling of water. The waste water is purified when it passes through the filter layer 22a and is caused to flow downward through the purification container 23, by gravity.

  and by a force generated by the lifting device

  of air 28 to suck it towards the bottom 27a of the air lifting tube 27. The purified water flows towards the

  bottom in the lower part 23a of the purification container

  tion 23 and is sucked mainly in the collecting chamber 25 while it is partly sucked in the bottom 27a of the air lifting tube 27. The collecting chamber 25 has a suitably long side wall 25b and the end 26a of the water pipe 26 is located at a suitable height inside the collecting chamber 25 so that no filtering material 22 can enter the water pipe 26. The purified water collected in the collecting chamber 25 is brought to the

  reservoir 31 by pipe 26, due to their difference

rence of water level.

  The filter material 22 carrying the solid substances is sucked into the bottom 27a of the air lifting tube 27 and lifted through it by the air which is injected therein by the air supply pipe 28a. When the filter material 22, part of the purified water and the air rise through the air lifting tube 27, the solid substances which adhere to the filter material

  22 are agitated and separated from the filter material 22.

  The separated solid substances, the filter material 22 and the water rise through the air lifting tube 27 and are discharged from the top 27b into the separating device 29. The solid substances, filter material 22 and the water (which l (usually called retrograde cleaning water) are stopped by the protective element 29b in the separating device 29 and caused to fall on the conical wall surface 29c of the hollow structure 29a. The filter material 22 cleaned in the air lifting tube 27 does not pass through the wall surface 29c defining a screen, but falls back into the purification container 23. The solid substances and the retrograde cleaning water pass through. through and arrive in the hollow structure 29a and form a retrograde cleaning waste which is

  in turn rejected by the exhaust pipe 30.

- 9 -

  We now refer to Figure 3 which illus-

  tre treatment of the retrograde cleaning waste which has been discharged by the purifier 21. The waste is brought to a settling tank for retrograde cleaning waste 33 in which a sludge is allowed to settle. The mud is sucked outside by the outlet 33a of the basin 33 and thus separated from a supernatant phase in the basin 33. The latter is brought to a waste water tank 34 and recycled from the latter to the purifier 21

  with the waste water which is brought to the reservoir 34.

  The purifier 21 constructed as described above has

  many advantages as will be shown below.

  Firstly, it allows the treatment for purifying waste water and the treatment for cleaning the filtering material 22 in the air lifting tube to take place simultaneously without any interruption. So,

  the purifier 21 has an improved operating speed.

  Continuous wastewater treatment can be carried out using a single purifier 21 which does not need to be

very large.

  Secondly, the cleaned filtering material 22 is practically free of any solid impurity and therefore ensures improved purification efficiency by biological treatment, since its cleaning is carried out at the same time as the purification treatment.

of waste water.

  The following table shows by way of example the water purification results which have been obtained with the apparatus constructed as described above and designed to treat a BOD load as indicated by the table:

- 10 -

  () (Wastewater)) (Wastewater: Wastewater: Wastewater) (domestic: from: from) (: treatment: fabrica-) (: food: pa- tion) (:: pier) (: :)

(:: :)

  (Load of -DBO :::) ((Kg / n? / Day): 4-to 5: 5 to 6: 3 to 4)

(: ::)

  (Quality of :: :) (wastewater :: :) (BOD; mg / 1: 100 to 120: 2000 to 2500: 90 to 120)

(: ::)

(Elimination of :::)

  (DB0: 93 to 96%: 87 to 90%: 94 to 96%)

(: ::)

(Elimination of :::)

  (COD: 85 to 87%: 83 to 85%: 65 to 70%)

(: ::)

  Thirdly, the filter material 22 is cleaned in the air lifting tube 27 and separated from the solid substances by the separating device 29 and the cleaned filter material 22 returns to the purification container 23. Therefore, there is no longer any for the cleaning of the filtering material 22, a fan or retrograde cleaning pump, a large water tank, or

associated automatic valve.

  Fourthly, only a small amount of filter material 22 is required because of its high efficiency of purifying water by biological treatment and no waste collecting chamber of the type which exists in the conventional apparatus is required. . The purification container, in the apparatus of the invention, is therefore

small. -

  Fifth, the solid substances fall into the hollow structure 29a with cleaning water

  retrograde and do not enter the purifying container

  since they are separated from the filter material 22 by the sieving action of the conical wall surface 29c of the separating device 29. The separating device

- 11 -

  29 prevents any solid substance from falling into water

  purified from the purification container 23.

  Sixth, the particles of filamentary material

  trante 22 leaving the air lifting tube 27 at the top 27a return to the purification container while rubbing against each other on the conical wall surface 29c of the separating device 29. This also promotes separation between the solid substances

  and the filter material 22 in the separating device 29.

  Seventh, it is possible to equip the device

  positive separator 29 of a vibrator to accelerate the

  separation of solid substances and filamentary matter

  trante 22 while physically separated

  by the conical wall surface 29c defining a screen.

  Eighth, the filter material 22 remains on the screen defined by the conical wall 29c of the device.

  separator 29 and effectively returns to the scrubber chamber

  ration 23 without falling into the hollow structure 29a with

solid substances.

  Ninth, the apparatus according to the invention does not require a settling tank of the type which is usually necessary in a process based on catalytic oxidation, comprising an activated sludge or

using sprayed water.

  We now refer to Figure 4, showing a

  flow-through type biological membrane purifier

  ash according to a second embodiment of the invention.

  The purifier 21A comprises a purification container 23A filled with a filtering material 22A, an aerator 24A provided in the purification container for bringing oxygen therein, several water collecting chambers 25A for collecting water biologically treated, a 26A water hose

  connected to each 25A water collection chamber, five

  air lift positive 28A each comprising a

  air lift tube 27A arranged vertically through

  towards the purification chamber 23A to suck in the air lifting tube 27A, at the bottom 27B thereof, the

- 12 -

  filter material 22A to which solid substances have adhered as a result of the biological treatment of waste water, and together lifting the filter material 22A and the solid substances, while separating the solid substances from the filter material 22A, several separating devices 29A each provided at the top 27c of one of the air lifting tubes 27A for separating the filter material 22A from the solid substances and bringing it back to the purification container 23A, and a discharge pipe 30A

  to remove solids from all available

separating agents 29.

  The device according to this second embodiment of the invention has the advantage of allowing the purification of a large amount of waste water at a time, in addition to the advantages

  of the device according to the first embodiment.

  Although the water hose 26, in the apparatus according to the first embodiment, has its water inlet 26a located inside the water collecting chamber 25, it is possible, instead, to connect said pipe to the side wall 25a of the water collecting chamber, as indicated in FIG. 5. This arrangement is used in the device according to the second embodiment. Although the water collecting chamber 25 or 25A and the air lifting tube 27. or 27A are of the unitary construction according to the first or the second embodiment of the invention, it is possible, instead

  from this, to form a water collecting chamber 25B pre-

  feeling a generally toric hollow space and placing in the center 35 of the toric space an air lifting tube 27 which is separated from the water collecting chamber

  B, as shown in figure 6. The collecting chamber

  The water trough 25B has a side wall defined by a part of the side wall of the purification container 23 and the water pipe 26 is connected to this part of the side wall. In the embodiment of Figure 7 a

- 13 -

  scum removal nozzle 32 is mounted at the top of the scrubber container 23 to remove floating foam-forming material floating at the surface of the wastewater at regular intervals. We can mix the scum removed with retrograde cleaning waste and transfer everything to the waste settling tank

retrograde cleaning 33.

  Although the air lifting tube 27 has been shown and described as being placed inside the purification container 23, it is possible instead to use an L-shaped air lifting tube having an inlet end located inside the purification container 23 and extending outside of it. In either case, the separating device 29 can also be located outside the container

treatment plant 23.

  Although the air supply pipe 28a, in the apparatus

  reil according to the first or the second mode of execution,

  either connected to the air lifting tube 27 or 27A perpen-

  specifically to this one, near its lower end

  27a and 27b, it is possible instead

  use an air supply pipe 35 arranged vertically-

  ment, forming an integral part of the air lifting tube 27 or 27A, as shown in FIG. 7. According to this variant, air is supplied to the tube 27 or 27A

at its upper end 35a.

  Another integrated set of air supply pipe and lifting tube is shown by way of example in FIGS. 8 and 9. It comprises an air supply pipe 35A formed coaxially around a delivery tube. air lift 27 or 27A. The air supply pipe A can be provided with an air supply orifice 37 in

  a point 36 intermediate between its upper ends

  lower and lower, as shown in Figure 10.

  As is evident from the description

  which precedes, the invention has many advantages: - it allows the biological treatment of used water

- 14 -

  and cleaning the filter material simultaneously without any interruption, - it provides improved water purification efficiency by biological treatment, - it does not require a fan or pump for retrograde cleaning of the filter material, nor large tank to receive the purified water, - it makes it possible to reduce the size of the purification container, - it prevents any solid impurities from mixing with the purified water, - it includes a separating device which allows a further separation between the solid impurities and the filter material,

  - it allows the use of a separate device

  rator fitted with a vibrator, - it recycles the filter material

  cleaned in the purification container without loss

ble, and

  - it eliminates the need for a decan basin

  tation of the type which is usually necessary for a

  process based for example on catalytic oxidation.

- 15 -

Claims (12)

  1.- Biological purifier with a downward flow type, characterized in that it comprises a purification container (23) filled with a filtering material (22), an aerator (24) provided in the container purification to bring oxygen there, a chamber (25a) for collecting biologically treated water, a water pipe (26) connected to the collecting chamber (25a), an air lifting device comprising a air lifting tube (27) arranged vertically through the purification container to suck in the air lifting tube, at the bottom of the latter, the filter material to which solid substances have adhered as a result of the treatment biological water and lift together the filter material and the solid substances while separating the solid substances from the filter material, a device (29) provided at the top of the air lifting tube for separating the solid substances from the filter material and bring the filter material back to the container d purification, and a pipe (30) for   remove solid substances from the separation device   tion. 2.- purifier according to claim 1, characterized   by the fact that the air tube (27) is arranged inside   laughter of the purification container (23).   3.- Purifier according to claim 2, characterized in that the air lifting tube (27) and the water collecting chamber (25) are of unitary construction. 4. A purifier according to claim 2, characterized in that the air lifting tube and the water collecting chamber (25) are separated from one another. 5.- Purifier according to claim 1, characterized in that the air lifting tube (27) is   straight and a. an inlet end located inside   laughter of the purification container (23). - 16 -   6. Purifier according to claim 1, characterized in that the air lifting tube is L-shaped and   has an inlet end located inside the container sewage treatment plant.   7.- Purifier according to claim 1, characterized in that it further comprises an air supply pipe (28a) which is separated from the air lifting tube (27)   and which is connected to it near its lower part.   8.- Purifier according to claim 1, characterized in that it further comprises an air supply pipe forming an integral part of the air lifting tube. 9.- Purifier according to claim 7, characterized in that the air supply pipe (35) surrounds   coaxially the air lifting tube (27, 27A).   10.- Purifier according to claim 1, characterized in that the water collecting chamber (23) comprises   a container (23a) having a bowl or poly section   gonal and having a downward opening, the water hose having a water inlet end located   inside this last container.   11.- Purifier according to claim 1, characterized in that the separator device (29) comprises a hollow structure having a conical wall (29c) provided with sieve openings of such size that   do not allow the passage of the filter material.   12.- Purifier according to claim 1, characterized in that the separator device (29) comprises a hollow structure having a conical wall provided with perforations or slots of a size such that   do not allow the passage of the filter material.