CA2050885A1 - Process for the biological treatment of waste water using microorganisms - Google Patents
Process for the biological treatment of waste water using microorganismsInfo
- Publication number
- CA2050885A1 CA2050885A1 CA 2050885 CA2050885A CA2050885A1 CA 2050885 A1 CA2050885 A1 CA 2050885A1 CA 2050885 CA2050885 CA 2050885 CA 2050885 A CA2050885 A CA 2050885A CA 2050885 A1 CA2050885 A1 CA 2050885A1
- Authority
- CA
- Canada
- Prior art keywords
- microorganisms
- waste water
- water
- contact section
- air
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 244000005700 microbiome Species 0.000 title claims abstract description 76
- 239000002351 wastewater Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 23
- 230000008569 process Effects 0.000 title claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 42
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 11
- 239000001301 oxygen Substances 0.000 claims abstract description 11
- 238000005276 aerator Methods 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 12
- 239000010802 sludge Substances 0.000 claims description 4
- 230000001174 ascending effect Effects 0.000 claims description 2
- 238000000746 purification Methods 0.000 abstract description 9
- 238000005273 aeration Methods 0.000 abstract description 2
- 238000002360 preparation method Methods 0.000 abstract 1
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical class COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 6
- 229920005372 Plexiglas® Polymers 0.000 description 6
- 235000015097 nutrients Nutrition 0.000 description 3
- 230000006978 adaptation Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000008213 purified water Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 241000894006 Bacteria Species 0.000 description 1
- 241000518994 Conta Species 0.000 description 1
- 240000004760 Pimpinella anisum Species 0.000 description 1
- 241001237728 Precis Species 0.000 description 1
- 241000142921 Tardigrada Species 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000000266 injurious effect Effects 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/006—Water distributors either inside a treatment tank or directing the water to several treatment tanks; Water treatment plants incorporating these distributors, with or without chemical or biological tanks
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/06—Aerobic processes using submerged filters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
Abstract The invention concerns a process for the biological treatment of waste water using microorganisms, in which the microor-ganisms breed and develop in a contact path (I) and in which optimum living conditions are maintained for the microorganisms by the addition Or waste water to be treated and appropriate quantities Or air (2). A portion Or the microorganisms leaving the contact path (I), which will have developed well in the soiled water, are fed back (6) into the contact path in order always to have exactly those microorganisms available that are particularly suitable for the waste water to be purified and at the same time suffi-cient quantities of these healthy microorganisms. In addition, a small sample of waste water is taken, well away from the contact path (1), as an indicator, and introduced (17) into the microorganism development area as a kind of early-warning enabling time-ly preparations to be made for the development of the microorganisms. This process, together with a device suitable for carrying it out, enables the degree of purification to be kept constant, the uniformity of the food supply and the wide and optimally bal-anced variety of microorganisms, as well as the balanced oxygen supply or efficiency of aeration, making it possible to adapt several variables, either individually or together, to changing conditions.
Description
2 ~
The pr sent invention relates to a process ~or the biological treatment oP waste water using microorganisms, the living conditions of which are ensured by the introduction o~ oxygen in a contact section that is arranged so as to be inclined slightly towards the surface of the water, Raid contact section having internal walls that are air-permeable and outer walls that are impermeable to air, the air and the contaminated waste water being introduced into the contact section approximately parallel to the surface o~ the water so as to permit development o~ the microorganisms. In addition, the present invention relates to an apparatus ~or carrying out the proce~s, said apparatus incorporating an underwat~r supporting ~ra~work in which a double-walled line, that is inclin~d ~lightly to the sur~aca of the water and contain~ the air bubble~, which also incorporates bafles to pr~vent th~se same bubbles ~rom rlsing pramaturely, and which also serve~ as a contact ~eation, accommodate~ the polluted waste watcr that is introduced through an aerator, and the air.
Such proce~Re~ ar~ u~ed for th~ biological purification of waste water, and primarily for regenerating water that has b~come heavily contaminated and ~ilty becau~e o~ a lack o~ oxygen. A
known apparatus that i~ used for this purpose (DE PS 25 23 591~
incorporates a water jet (vacuum) pump that generates a water-air mixture that i~ then pas~ed through a line such that the air bubbles do not rise too rapidly. The line is extended and 8 ~
provided with an inner wall that is permeable to air and an outer wall that is impermeable to air such that the individual air bubbles, which are as small as possible, have to travel a great distance and are in close contact with the water during this time. In this way, oxygen-saturated water is generatad in a specific area so that the bacteria that destroy the sludge are sustained and can multiply as rapidly as possible. ~he apparatus rests on its framework on the bottom of the body of water and can be moved from on~ location to another, as required. In order to ensure the contact between the air bub~les and the water that is required, such contact sections are 15 m and more long. Within the interior of the contact section there are built-in structures on which ~he individual microorganisms can settle and develop in order to ensure that the water is purifie/i as thoroughly as possible in the shortest possible time. How2ver, it is a disadvantage that the microorganisms dev~lop more or less at random, depending on the availability o~ the oxygen and nutrients, i.e., depending on the pollutants that are present.
In addition, the microorganisms that exhibit optimum work capacity are carried off with the purified waste water which is, in part, desirable, although, on the other hand, it restricts the uniformity with which the microorganisms as a whole develop.
This becomes particularly problematic if the composition of the waste water changes. Then, either there are insufficient microorganisms present or the microorganisms that are present cannot adapt, or else the microorganisms that are required are available only in small or the very minimum numbers. Patent specification GB-A 587 400 discloses a process for tr~ating waste water in a simple contact section that i~ aerated transversely to the direction oP flow. Some of the microorganisms that leave the contact section are rPturned into the contact section with the sludg~ that has been picked up. Quite apart from the fact that only insufficient aeration, i.e., provision of oxyg2n, is achieved, this refersnce to the return of sludge maXes it quite clear that only limited success can be anticipated from such purification.
It is the task of the present invention to create a waste water treatment process with even and lasting good purification results, and which can also adapt to variously composed waste water quickly and at no great cost. In as~dition, the present invention will describe an apparatus that is required for carrying out the process according to the present invention.
According to the present invQntion, this task has been solved in that some of the micxoorganisms that leave th~ contact section, and which have developed in the contaminated water, are deliberately trapp~d and returned to the conta¢t section, and in that, in addition, a small secondary flow of contaminated waste water is introduced in advance into the contact section, to serve as a type of indicator. The manner in which the required oxygen is introduced into the contact section or into an appropriate 2 ~
activation area is not, initially, of importance, because a sufficient quantity is ensured and the growth of the microorganisms that are suitable in each case is improved by the return of healthy microorganisms that arP suitable for repopulation. When thi~ is done, the microorganisms that are returned are those that no longer find sufficient nutrients in the purified water and are thus optimal for th~ continued destruction of th~ injurious substances and which are best suited for further developing the required strains of microorganisms.
Furthermore, they have been able to develop in thP contaminated water with due regard to its properties, so that pr~cisely those strains are present that are required for the optimal biological treatment of the waste water. The proce~s itself can be shortened, advantageously by this sort of deliberate management of the process and treatment of the microorganisms, because healthy microorganisms that are be t suited for the particular purification can be made available in a sufficient quantity. In addition, allowance is al~o made for the fact that the living condi~ions ~or the microorganisms can vary very gr~atly depending on the degree and type of contamination that is involved~
Because of the early introduction of small quantities o~ th~
waste water that is introduced into the contact section, which represents a type of early warning system, any sudden destruction of the microorganisms or failure of the purification process is prevented. The small secondary ~low of waste water has no ef~ect if the waste water can be purified by the microorganisms that are 2 ~
present. However, if another type of pollution occurs, or if the composition of the waste water changes, then this small secondary flow will ensure that suitable microorganisms have been pre-cultivated so that thay develop very quickly on the arrival of the waste water that is of a different composition and can therefore ensure that purification of all the waste water continues to be ensured. More advantageously, this permits a smooth transition w.ithout the need for any special measures to be taken. It is as if the adaptation takes pla~e completely automatically as a result of the indicator.
According to one practical dsvalopment of the present invention, prolvision is made thal: the microorganisms are fed back into the contact section in a direction opposite to the main flow. The microorganisms which otherwise would no lo:nger find su~ficient nutrients in the puriîied water and would thus die are now distributed evenly throughout the contact section such that they can o~ce again ~eed and multiply optimally. This is facilitated by introduction in a direction opposite that of the normal flow, which ensures the even distribution of the microorganisms.
A further possibility ~or achieving the even distribution of the microorganisms is to draw in the secondary flow of microorganisms at a specific distance behind (as viewed in the direction of flow) the point o~ introduction of the air and then distribute it together with the air and water within the contact section. The 8 ~
microorganisms would thus be introduced in the area of the water-jet pump or shortly thereafter, so that it i5 flushed into th~
area of the contact section with the ~low of fresh waste water into which the greatest quantity of air bubbles have been introduced. When this is done, however, on~ has to accept the fact that here the water has not been enriched with oxygen so that the method described heretofore, in which the microorganisms are introduced into the contact section in a direction opposite the normal direction of flow, at a specific distance ~rom the point o~ introduction, i.e., from the aerator, is the best.
The number of microorganisms and their development thu~ depends, essentially, on the level of oxygen saturation in the water. For this reason, special value is placed on the proper removal of the microorganisms at an appropriate distance and, on the other hand, the quantity is to be appropriately varied in which connection, according to the pr*sent inv~ntion, provision is made such that the point of withdrawal is displacad either in the direction oX
flow or counter to this depending on tha level of oxygen saturation in the water and the quantity of microorganisms that are present.
As a rule, it is sufficient if th~ secondary ~low o~ polluted waste water is introduc~d at a specific point in the colonization area of the microorganisms. Then, if th~ most rapid poss'ble distribution is necessary, or if the change in the water is v~ry marked, and has been previously determlnad by extra measureR, it can be advantageous to introduce the secondary flow into the cnntact section together with air and waste water if the composition of the waste water is such as to endanger all o~ the microorganisms. This will speed up adaptation, particularly i~, according to a further advantageous development o~ the present process, the quantity o~ the secondary flow is lncreased. This paves the way ~or continuous cultivation and growth o~ the microorganisms, which will be necessary when the first of the waste water of di~ferent composition arrives.
A ~urther possibility for adapting the clevelopment o~ the microorganisms i5 that whereby the addit:ion of polluted waste water is reduced and at the same time the removal point is moved closer to the point at which the air ancl the polluted waete water is introduced. In this way, one can tah:e into account the varying composition o~ the wa te water.
I~ particular,i~ tha pollution that has already been considered becomes greater than was formerly the case, the process according to the present invention ensures that the same degree of success in puri~ication i5 nonetheless ashieved.
In the case of particularly serious changes in the ~omposition o~
the waste water, it may be advantageou~ to insert precultivated microorganisms that are adapted to the new composition o~ the waste water into the circulatory system via the removal point, until conditions become stabilized once again. However, this variation of the process demands continuous observation and moni~oring of the waste water in order that the deliberately cultivated microorganisms can be added promptly, this being done at a poin~ in time when they are actually requ~red and when they can also be ~ound at the re~oval point and then ~ed back into the circulatory sy~tPm once aga1n~ and if necessary with additional precultivated microorganisms.
In order to carry out the pre~ent invention, an app~ratu~ i5 used ln which the return o~ the cultivated microorganisms to the cirçulatory system i~ achieved in that a removal polnt i associated with the contact section in the direction of flow, this removal point being connected to the aerator and through a feedllne for ~resh microor~anis~s. Thu!3, the microorganisms that are optimal for purifying the water and for cultivation are picked up through the removal point and then brought back through the feedline ~or ~resh orqani ms and to or into the aerator. ~hen this i~ don~, one can explsit the suction o~ the aerator in ~rder to use it to capture the microorganism~ or to draw the~ in and return them once morQ to the contact ~ection.
The introduction of the ~mall secondary flow o~ waste w~ter into the area of the aerator ensures constant operation. When this is done, the in-flow openings and t~us the length oP the withdrawal line is to be ~uch that su~icient time is available to 2~88~
precultivate the microorganisms that are suitable for the changing waste water.
However, the deliberate return of the microorganisms is ensured, in particular, in that the withdrawal point is aquipped with a vacuum pump and has, on the outlet side, a plurality of outlet noæzles that discharge against the normal direction of ~low. On the one hand, such a configuration ensures the removal of precisely those organisms that are required for further cultivation and, on the other hand, ensures their even removal through the whole cross section of the contact section, in which connection, outlet nozzles are understood to be those openings that ensure that the microorganisms are mixed with the oxygen impregnated waste water, oppo ite to the normal direction of ~low, at least for a short distance.
The even removal of the water mixed with th~ microorganisms is optimized in that the removal point has a plurality of removal pipes that are di tributed ovsr a large cross section.
The displacement of the removal point into the precise area where it picks up particularly suitable and healthy microorqanisms is ensured in that the faedline for the fresh organisms is configured so as to telescope, and in that it haæ an as~ociated drive system. The drive system can be used to retract the telescopic line and also to extend it in order to shift the removal point to the particular area that is required.
Optimal safety against changing waste water is achiev~d, according to the present invention, in that the length of the withdrawal line is selected so as to correspond to the average growth rate of anaerobic microorganisms that are ~ound in activated sludge.
The present invention is characterized in particular in that it describes a pro~ess and an apparatus with which the biological purification of waste water can be systematized such ~hat a constant level of success in the puri~ication process is ensured, even if the w~ste water change~ with regard to the quantity of pollution or with regard to the type of said pollution. By the deliberate cultivation of precisely those organisms that are equal to the waste water problems, and by th~ir timely colonization.in the area of the aerator and the contact section, it is possible to ensure continuous long-term operation of an appropriate appar~tus and the constant level of success that is desired.
Additional details and advantages of the object o~ the present invention, are set out in the ~ollowing description, which i~
based on the drawings appended hereto, which show a preferred embodiment with the necessary details and individual parts.
These drawings show the followin~:
2 ~
igure 1: a simplified drawing o~ a contact section for waste water purification:
Fi~ure 2: a drawing of the distributor pipe for the return of the microorganisms;
Figure 3~ the withdrawal line ~or the waste water quantity indicator;
Figure 4: a drawing, at larger scale, o~ an apparatus that is suitable for carryinq ouk the process.
Figure 1 is a simplified drawing of a contact section, this contact section (1) being shown here With only one wall far purposes of simplification. At the start of the section there is an aerator (23, and tha removal point (4) is at the end (3) o~
the section; microorganisms that are fully developed or nearly so are withdrawn through this point and returned to the area of the aerator (2). To this end, the withdrawal point has a suction pump (5) and is connected to the aerator (2~ through the fresh organism line (6).
In order that the withdrawal point (4~ can be arranged at different points, the connection~ between the individual sections of the fresh organism line (6~ are configured as telescopic connections (7, 8). Because of this, the line ~6) can either be retracted or extended, depending on the distance that is required between the withdrawal point (4) and the aerator (2). Figure 1 does not show that a motorized drive system can be incorporated in order to permit this telescoping action to be implemented either from the surface of the water or ~rom a ~lo~ting platform.
The end o~ the fre~h organism line (6) ~orms a distributor pipe (9) that i5 shown in detail in figure 2. The distributor pipe (9) is here equipped with a plurality of outlet nozzles (10, 11), in order that it can ejeet purified water that contain~ a large number of healthy microorganisms evenly and over an appropriately large area, this being done opposite to the normal ~low in which the waste water that is to be purified .1~ ~lowing in. The outlet nozzles (10, 11~ are basically op~nings or drillings that are simply directed against the direction o~ ~low of the waste water.
The waste water that ~low~ into the aontact section (~) bears the reference number (12), with the increaslng degr~e o~ puri~ication within the contact ection (1) being inclicat~d in that the di~tance b~tweQn khe l.ines that run oblic~ely from the top downwards become6 ever greater. The oxygen-saturated water bears the reference number (13); the oxyyen content of this water is reduced somewhat after the 8 ~
1~
aerator (2~ because o~ consumption hy the microorgani~ms.
This, too, is shown in that the den~ity of the point~ decreases from the start of the section to the end oP the ~ection (3). In the same way, the lines that extend fro~ below obliquely upwards to the le~t show the growth area ( 14 ) o~ the microorganisms. The distance between the lines that run ~rom bottom right upwards to top left grows ~horter according to the guantity o~
microorganism~.
The removal pipe (15) is positioned approximately in the area o~
the zone that is optimally enriched with microorganisms; this withdrawal pipe (15) incorporate~ a plurality o~ openings in order that it can pick up watar enrichedl with ~icroorganisms from di~ferent areas. The individual op~ning~ can be provlded with sl ide8 SO that water containing mi~roorganism~ can be removed from the mo~t varied horizons (~trata~
In the samQ way, a removal line (17) 9 which i~ connect~d through the conne~tor (16), and through which a small quantity o~
contaminated water or waste water that i.s to be purified and which ha~ been removed largely from the area ahead of the contact section (1) is moved to the coloniæation area ~or th~
microorganisms, also ends in the area of the aerator (2), in order that early warning can be ensured by this m~ans. Now, i~
the composition of the waste water that i~ to be purified changes, th~re will be a ~imultaneous r20rientation during the development in the area in which the microorganisms are colonized~ because the corresponding waste water will have been made available here as well. As can be seen from figure 1, there is a direct introduction of this small flow of waste water into the aerator (2) through this connector (16), although the removal line (17) can also discharge at the upper or lower edge of the contact section (1).
As before, the withdrawal line tl7) ends in the same way ahead of the contact section (1), through a type of distributor pipe, in which connPction here, too, there is a plurality of in-flow openings (18, 20) with which waste water c~n be drawn in through the pump (lg) and then moved into the growth area o~ the microorganisms in the desired small quantity.
Finally, figure 4 also shows a simplified version of an apparatus through which the process according to the present invention can be implemented, and wherein it is also clear that the ~ontact section (1) is associated with an underwater supporting ~ramework (2~) that is in the form of a plexiglass pipe (24); the distance between the plexiglass pipe (24) and the surface of the water can be adjusted precis*ly by means oP this framework, and it can then kept in position thereby. The contaminated water is drawn in through the water-jet pump (23) and at the same time, air is forced into it so that a water air mixture flows into the area of the plexiglass pipe (24) through the aerator ~2). In order to 8 ~ ~
prevent the air bubbles from rising, and to establish areas where the microorganlsms can settle, within the plexiglass pipe (24) th0re is a plurality of parts (25~ that can be of the most varied shapes. The plexiglass pipe (24), i.e~, the contact section (1), is inclined slightly to the surface of the water, in which connection a second wall has been eliminated from here as well, because adequate security is provided by the parts (25) that prevent the premature the bubbles from ascending prematurely. The configuration as a plexiglass pipe (24) also entails the major advantage that the light required for the growth of the microorganisms will be made available in a sufficient quantity.
In the case of the fresh organism line (6~ that is also shown in figure 4, the remov~l point (4) is shown as a ~imple connector in which connection the water that contains l;he quantity of microorganisms and which is fed back into the area o~ the aerator t2) can be precisely determined by selection of the diameter of the fresh organism line (6)l by the capacity of the pump, and by its adjustment as such The parts that are shown in Figure 4 are in the form of a kind of plastic cord on which the microorgani~ms can colonize. These parts (25, 25', 25 ") can also be of different shapas, as discussed heretofore, in which connection it is expedient to use parts ~25, 25', 25 ") that make available large areas on which the air bubbles and the microoryanisms can settle.
The pr sent invention relates to a process ~or the biological treatment oP waste water using microorganisms, the living conditions of which are ensured by the introduction o~ oxygen in a contact section that is arranged so as to be inclined slightly towards the surface of the water, Raid contact section having internal walls that are air-permeable and outer walls that are impermeable to air, the air and the contaminated waste water being introduced into the contact section approximately parallel to the surface o~ the water so as to permit development o~ the microorganisms. In addition, the present invention relates to an apparatus ~or carrying out the proce~s, said apparatus incorporating an underwat~r supporting ~ra~work in which a double-walled line, that is inclin~d ~lightly to the sur~aca of the water and contain~ the air bubble~, which also incorporates bafles to pr~vent th~se same bubbles ~rom rlsing pramaturely, and which also serve~ as a contact ~eation, accommodate~ the polluted waste watcr that is introduced through an aerator, and the air.
Such proce~Re~ ar~ u~ed for th~ biological purification of waste water, and primarily for regenerating water that has b~come heavily contaminated and ~ilty becau~e o~ a lack o~ oxygen. A
known apparatus that i~ used for this purpose (DE PS 25 23 591~
incorporates a water jet (vacuum) pump that generates a water-air mixture that i~ then pas~ed through a line such that the air bubbles do not rise too rapidly. The line is extended and 8 ~
provided with an inner wall that is permeable to air and an outer wall that is impermeable to air such that the individual air bubbles, which are as small as possible, have to travel a great distance and are in close contact with the water during this time. In this way, oxygen-saturated water is generatad in a specific area so that the bacteria that destroy the sludge are sustained and can multiply as rapidly as possible. ~he apparatus rests on its framework on the bottom of the body of water and can be moved from on~ location to another, as required. In order to ensure the contact between the air bub~les and the water that is required, such contact sections are 15 m and more long. Within the interior of the contact section there are built-in structures on which ~he individual microorganisms can settle and develop in order to ensure that the water is purifie/i as thoroughly as possible in the shortest possible time. How2ver, it is a disadvantage that the microorganisms dev~lop more or less at random, depending on the availability o~ the oxygen and nutrients, i.e., depending on the pollutants that are present.
In addition, the microorganisms that exhibit optimum work capacity are carried off with the purified waste water which is, in part, desirable, although, on the other hand, it restricts the uniformity with which the microorganisms as a whole develop.
This becomes particularly problematic if the composition of the waste water changes. Then, either there are insufficient microorganisms present or the microorganisms that are present cannot adapt, or else the microorganisms that are required are available only in small or the very minimum numbers. Patent specification GB-A 587 400 discloses a process for tr~ating waste water in a simple contact section that i~ aerated transversely to the direction oP flow. Some of the microorganisms that leave the contact section are rPturned into the contact section with the sludg~ that has been picked up. Quite apart from the fact that only insufficient aeration, i.e., provision of oxyg2n, is achieved, this refersnce to the return of sludge maXes it quite clear that only limited success can be anticipated from such purification.
It is the task of the present invention to create a waste water treatment process with even and lasting good purification results, and which can also adapt to variously composed waste water quickly and at no great cost. In as~dition, the present invention will describe an apparatus that is required for carrying out the process according to the present invention.
According to the present invQntion, this task has been solved in that some of the micxoorganisms that leave th~ contact section, and which have developed in the contaminated water, are deliberately trapp~d and returned to the conta¢t section, and in that, in addition, a small secondary flow of contaminated waste water is introduced in advance into the contact section, to serve as a type of indicator. The manner in which the required oxygen is introduced into the contact section or into an appropriate 2 ~
activation area is not, initially, of importance, because a sufficient quantity is ensured and the growth of the microorganisms that are suitable in each case is improved by the return of healthy microorganisms that arP suitable for repopulation. When thi~ is done, the microorganisms that are returned are those that no longer find sufficient nutrients in the purified water and are thus optimal for th~ continued destruction of th~ injurious substances and which are best suited for further developing the required strains of microorganisms.
Furthermore, they have been able to develop in thP contaminated water with due regard to its properties, so that pr~cisely those strains are present that are required for the optimal biological treatment of the waste water. The proce~s itself can be shortened, advantageously by this sort of deliberate management of the process and treatment of the microorganisms, because healthy microorganisms that are be t suited for the particular purification can be made available in a sufficient quantity. In addition, allowance is al~o made for the fact that the living condi~ions ~or the microorganisms can vary very gr~atly depending on the degree and type of contamination that is involved~
Because of the early introduction of small quantities o~ th~
waste water that is introduced into the contact section, which represents a type of early warning system, any sudden destruction of the microorganisms or failure of the purification process is prevented. The small secondary ~low of waste water has no ef~ect if the waste water can be purified by the microorganisms that are 2 ~
present. However, if another type of pollution occurs, or if the composition of the waste water changes, then this small secondary flow will ensure that suitable microorganisms have been pre-cultivated so that thay develop very quickly on the arrival of the waste water that is of a different composition and can therefore ensure that purification of all the waste water continues to be ensured. More advantageously, this permits a smooth transition w.ithout the need for any special measures to be taken. It is as if the adaptation takes pla~e completely automatically as a result of the indicator.
According to one practical dsvalopment of the present invention, prolvision is made thal: the microorganisms are fed back into the contact section in a direction opposite to the main flow. The microorganisms which otherwise would no lo:nger find su~ficient nutrients in the puriîied water and would thus die are now distributed evenly throughout the contact section such that they can o~ce again ~eed and multiply optimally. This is facilitated by introduction in a direction opposite that of the normal flow, which ensures the even distribution of the microorganisms.
A further possibility ~or achieving the even distribution of the microorganisms is to draw in the secondary flow of microorganisms at a specific distance behind (as viewed in the direction of flow) the point o~ introduction of the air and then distribute it together with the air and water within the contact section. The 8 ~
microorganisms would thus be introduced in the area of the water-jet pump or shortly thereafter, so that it i5 flushed into th~
area of the contact section with the ~low of fresh waste water into which the greatest quantity of air bubbles have been introduced. When this is done, however, on~ has to accept the fact that here the water has not been enriched with oxygen so that the method described heretofore, in which the microorganisms are introduced into the contact section in a direction opposite the normal direction of flow, at a specific distance ~rom the point o~ introduction, i.e., from the aerator, is the best.
The number of microorganisms and their development thu~ depends, essentially, on the level of oxygen saturation in the water. For this reason, special value is placed on the proper removal of the microorganisms at an appropriate distance and, on the other hand, the quantity is to be appropriately varied in which connection, according to the pr*sent inv~ntion, provision is made such that the point of withdrawal is displacad either in the direction oX
flow or counter to this depending on tha level of oxygen saturation in the water and the quantity of microorganisms that are present.
As a rule, it is sufficient if th~ secondary ~low o~ polluted waste water is introduc~d at a specific point in the colonization area of the microorganisms. Then, if th~ most rapid poss'ble distribution is necessary, or if the change in the water is v~ry marked, and has been previously determlnad by extra measureR, it can be advantageous to introduce the secondary flow into the cnntact section together with air and waste water if the composition of the waste water is such as to endanger all o~ the microorganisms. This will speed up adaptation, particularly i~, according to a further advantageous development o~ the present process, the quantity o~ the secondary flow is lncreased. This paves the way ~or continuous cultivation and growth o~ the microorganisms, which will be necessary when the first of the waste water of di~ferent composition arrives.
A ~urther possibility for adapting the clevelopment o~ the microorganisms i5 that whereby the addit:ion of polluted waste water is reduced and at the same time the removal point is moved closer to the point at which the air ancl the polluted waete water is introduced. In this way, one can tah:e into account the varying composition o~ the wa te water.
I~ particular,i~ tha pollution that has already been considered becomes greater than was formerly the case, the process according to the present invention ensures that the same degree of success in puri~ication i5 nonetheless ashieved.
In the case of particularly serious changes in the ~omposition o~
the waste water, it may be advantageou~ to insert precultivated microorganisms that are adapted to the new composition o~ the waste water into the circulatory system via the removal point, until conditions become stabilized once again. However, this variation of the process demands continuous observation and moni~oring of the waste water in order that the deliberately cultivated microorganisms can be added promptly, this being done at a poin~ in time when they are actually requ~red and when they can also be ~ound at the re~oval point and then ~ed back into the circulatory sy~tPm once aga1n~ and if necessary with additional precultivated microorganisms.
In order to carry out the pre~ent invention, an app~ratu~ i5 used ln which the return o~ the cultivated microorganisms to the cirçulatory system i~ achieved in that a removal polnt i associated with the contact section in the direction of flow, this removal point being connected to the aerator and through a feedllne for ~resh microor~anis~s. Thu!3, the microorganisms that are optimal for purifying the water and for cultivation are picked up through the removal point and then brought back through the feedline ~or ~resh orqani ms and to or into the aerator. ~hen this i~ don~, one can explsit the suction o~ the aerator in ~rder to use it to capture the microorganism~ or to draw the~ in and return them once morQ to the contact ~ection.
The introduction of the ~mall secondary flow o~ waste w~ter into the area of the aerator ensures constant operation. When this is done, the in-flow openings and t~us the length oP the withdrawal line is to be ~uch that su~icient time is available to 2~88~
precultivate the microorganisms that are suitable for the changing waste water.
However, the deliberate return of the microorganisms is ensured, in particular, in that the withdrawal point is aquipped with a vacuum pump and has, on the outlet side, a plurality of outlet noæzles that discharge against the normal direction of ~low. On the one hand, such a configuration ensures the removal of precisely those organisms that are required for further cultivation and, on the other hand, ensures their even removal through the whole cross section of the contact section, in which connection, outlet nozzles are understood to be those openings that ensure that the microorganisms are mixed with the oxygen impregnated waste water, oppo ite to the normal direction of ~low, at least for a short distance.
The even removal of the water mixed with th~ microorganisms is optimized in that the removal point has a plurality of removal pipes that are di tributed ovsr a large cross section.
The displacement of the removal point into the precise area where it picks up particularly suitable and healthy microorqanisms is ensured in that the faedline for the fresh organisms is configured so as to telescope, and in that it haæ an as~ociated drive system. The drive system can be used to retract the telescopic line and also to extend it in order to shift the removal point to the particular area that is required.
Optimal safety against changing waste water is achiev~d, according to the present invention, in that the length of the withdrawal line is selected so as to correspond to the average growth rate of anaerobic microorganisms that are ~ound in activated sludge.
The present invention is characterized in particular in that it describes a pro~ess and an apparatus with which the biological purification of waste water can be systematized such ~hat a constant level of success in the puri~ication process is ensured, even if the w~ste water change~ with regard to the quantity of pollution or with regard to the type of said pollution. By the deliberate cultivation of precisely those organisms that are equal to the waste water problems, and by th~ir timely colonization.in the area of the aerator and the contact section, it is possible to ensure continuous long-term operation of an appropriate appar~tus and the constant level of success that is desired.
Additional details and advantages of the object o~ the present invention, are set out in the ~ollowing description, which i~
based on the drawings appended hereto, which show a preferred embodiment with the necessary details and individual parts.
These drawings show the followin~:
2 ~
igure 1: a simplified drawing o~ a contact section for waste water purification:
Fi~ure 2: a drawing of the distributor pipe for the return of the microorganisms;
Figure 3~ the withdrawal line ~or the waste water quantity indicator;
Figure 4: a drawing, at larger scale, o~ an apparatus that is suitable for carryinq ouk the process.
Figure 1 is a simplified drawing of a contact section, this contact section (1) being shown here With only one wall far purposes of simplification. At the start of the section there is an aerator (23, and tha removal point (4) is at the end (3) o~
the section; microorganisms that are fully developed or nearly so are withdrawn through this point and returned to the area of the aerator (2). To this end, the withdrawal point has a suction pump (5) and is connected to the aerator (2~ through the fresh organism line (6).
In order that the withdrawal point (4~ can be arranged at different points, the connection~ between the individual sections of the fresh organism line (6~ are configured as telescopic connections (7, 8). Because of this, the line ~6) can either be retracted or extended, depending on the distance that is required between the withdrawal point (4) and the aerator (2). Figure 1 does not show that a motorized drive system can be incorporated in order to permit this telescoping action to be implemented either from the surface of the water or ~rom a ~lo~ting platform.
The end o~ the fre~h organism line (6) ~orms a distributor pipe (9) that i5 shown in detail in figure 2. The distributor pipe (9) is here equipped with a plurality of outlet nozzles (10, 11), in order that it can ejeet purified water that contain~ a large number of healthy microorganisms evenly and over an appropriately large area, this being done opposite to the normal ~low in which the waste water that is to be purified .1~ ~lowing in. The outlet nozzles (10, 11~ are basically op~nings or drillings that are simply directed against the direction o~ ~low of the waste water.
The waste water that ~low~ into the aontact section (~) bears the reference number (12), with the increaslng degr~e o~ puri~ication within the contact ection (1) being inclicat~d in that the di~tance b~tweQn khe l.ines that run oblic~ely from the top downwards become6 ever greater. The oxygen-saturated water bears the reference number (13); the oxyyen content of this water is reduced somewhat after the 8 ~
1~
aerator (2~ because o~ consumption hy the microorgani~ms.
This, too, is shown in that the den~ity of the point~ decreases from the start of the section to the end oP the ~ection (3). In the same way, the lines that extend fro~ below obliquely upwards to the le~t show the growth area ( 14 ) o~ the microorganisms. The distance between the lines that run ~rom bottom right upwards to top left grows ~horter according to the guantity o~
microorganism~.
The removal pipe (15) is positioned approximately in the area o~
the zone that is optimally enriched with microorganisms; this withdrawal pipe (15) incorporate~ a plurality o~ openings in order that it can pick up watar enrichedl with ~icroorganisms from di~ferent areas. The individual op~ning~ can be provlded with sl ide8 SO that water containing mi~roorganism~ can be removed from the mo~t varied horizons (~trata~
In the samQ way, a removal line (17) 9 which i~ connect~d through the conne~tor (16), and through which a small quantity o~
contaminated water or waste water that i.s to be purified and which ha~ been removed largely from the area ahead of the contact section (1) is moved to the coloniæation area ~or th~
microorganisms, also ends in the area of the aerator (2), in order that early warning can be ensured by this m~ans. Now, i~
the composition of the waste water that i~ to be purified changes, th~re will be a ~imultaneous r20rientation during the development in the area in which the microorganisms are colonized~ because the corresponding waste water will have been made available here as well. As can be seen from figure 1, there is a direct introduction of this small flow of waste water into the aerator (2) through this connector (16), although the removal line (17) can also discharge at the upper or lower edge of the contact section (1).
As before, the withdrawal line tl7) ends in the same way ahead of the contact section (1), through a type of distributor pipe, in which connPction here, too, there is a plurality of in-flow openings (18, 20) with which waste water c~n be drawn in through the pump (lg) and then moved into the growth area o~ the microorganisms in the desired small quantity.
Finally, figure 4 also shows a simplified version of an apparatus through which the process according to the present invention can be implemented, and wherein it is also clear that the ~ontact section (1) is associated with an underwater supporting ~ramework (2~) that is in the form of a plexiglass pipe (24); the distance between the plexiglass pipe (24) and the surface of the water can be adjusted precis*ly by means oP this framework, and it can then kept in position thereby. The contaminated water is drawn in through the water-jet pump (23) and at the same time, air is forced into it so that a water air mixture flows into the area of the plexiglass pipe (24) through the aerator ~2). In order to 8 ~ ~
prevent the air bubbles from rising, and to establish areas where the microorganlsms can settle, within the plexiglass pipe (24) th0re is a plurality of parts (25~ that can be of the most varied shapes. The plexiglass pipe (24), i.e~, the contact section (1), is inclined slightly to the surface of the water, in which connection a second wall has been eliminated from here as well, because adequate security is provided by the parts (25) that prevent the premature the bubbles from ascending prematurely. The configuration as a plexiglass pipe (24) also entails the major advantage that the light required for the growth of the microorganisms will be made available in a sufficient quantity.
In the case of the fresh organism line (6~ that is also shown in figure 4, the remov~l point (4) is shown as a ~imple connector in which connection the water that contains l;he quantity of microorganisms and which is fed back into the area o~ the aerator t2) can be precisely determined by selection of the diameter of the fresh organism line (6)l by the capacity of the pump, and by its adjustment as such The parts that are shown in Figure 4 are in the form of a kind of plastic cord on which the microorgani~ms can colonize. These parts (25, 25', 25 ") can also be of different shapas, as discussed heretofore, in which connection it is expedient to use parts ~25, 25', 25 ") that make available large areas on which the air bubbles and the microoryanisms can settle.
Claims (12)
1. A process for the biological treatment of waste water by using microorganisms, the living conditions of which are ensured by the introduction of oxygen into a contact section that is inclined slightly relative to the surface of the water, this having an inner wall that is air permeable and an outer wall that is not permeable to air, air and contaminated water being introduced into the contact section approximately parallel to the surface of the water in order to develop the microorganisms, characterized in that some of the microorganism, that leave the contact section, and which have developed in the contaminated water, are deliberately trapped and re-introduced into the contact section; and in that, in addition, a small secondary flow of contaminated waste water is introduced into the colonization area of the microorganisms within the contact section as a kind of indicator.
2. A process as defined in claim 1, characterized in that the quantity of microorganisms is reintroduced into the contact section in a direction opposite to the normal flow.
3. A process as defined in claim 1, characterized in that the quantity of microorganisms is withdrawn at a preset distance in the direction of flow after the point at which the air is introduced and then distributed within the contact section together with the air and water.
4. A process as defined in claim 1 and claim 3, characterized in that the removal point is displaced either in or against the normal direction of flow depending on the oxygen saturation of the water and the quantity of microorganisms that are available.
5. A process as defined in claim 1, characterized in that in the event that the composition of the waste water is such as to endanger the microorganisms as a whole, the secondary flow is introduced into the contact section together with air and waste water.
6. A process as defined in claim 3 and claim 5, characterized in that the addition of contaminated waste water is reduced and at the same time the removal point is moved closer to the input point for air and contaminated waste water.
7. A process as defined in claim 1 and one or more of the subsequent claims, characterized in that the precultivated microorganisms that have been adapted to the new composition of the waste water are introduced into the circulatory system through the removal point until restabilization occurs.
8. An apparatus for carrying out the process as defined in claim 1 or one or more of the subsequent claims, with an underwater supporting framework in which a double-walled line that is inclined slightly relative to the surface of the water is arranged, this line incorporatinq parts that contain the air bubbles and prevent these from ascending prematurely and which serves as a contact section, accommodates the contaminated waste water that has been introduced through an aerator, characterized in that a removal point (4) follows the contact section (1) in the direction of flow and is connected through a fresh organism line (6) to the aerator (2), said aerator having a connector (16) to which a removal line (17) of small cross section and an in-flow opening (18) that is installed well ahead of the aerator opposite the direction of flow are connected.
9. An apparatus as defined in claim 8, characterized in that the removal point (4) is provided with a suction pump (5) and, on the outlet side, with a plurality of outlet nozzles (10, 11). which discharge in a direction opposite to the normal direction of flow.
10. An apparatus as defined in claim 8 and claim 9, characterized in that the removal point (4) has a plurality of removal pipes (15) that are distributed over a large cross section.
11. An apparatus as defined in claim 8, characterized in that the fresh organism line (6) is configured 80 as to telescope: and that a drive system is associated with this.
12. An apparatus as defined in claim 8, characterized in that the length of the removal line (17) is selected in accordance with the average growth rate of anaerobic microorganisms that occur in activated sludge.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3911789.8 | 1989-04-11 | ||
| DE19893911789 DE3911789A1 (en) | 1989-04-11 | 1989-04-11 | METHOD FOR BIOLOGICAL WASTEWATER TREATMENT WITH THE AID OF MICROORGANISMS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2050885A1 true CA2050885A1 (en) | 1990-10-12 |
Family
ID=6378386
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2050885 Abandoned CA2050885A1 (en) | 1989-04-11 | 1990-03-21 | Process for the biological treatment of waste water using microorganisms |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5294340A (en) |
| EP (1) | EP0467896B1 (en) |
| JP (1) | JPH04504374A (en) |
| AU (1) | AU632551B2 (en) |
| BR (1) | BR9007285A (en) |
| CA (1) | CA2050885A1 (en) |
| DE (2) | DE3911789A1 (en) |
| ES (1) | ES2043364T3 (en) |
| WO (1) | WO1990011971A1 (en) |
| ZA (1) | ZA898818B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5554291A (en) * | 1992-10-23 | 1996-09-10 | Scanzillo; Joseph G. | Methods and apparatus for biodegradation of polluted fluids |
| US6348147B1 (en) * | 2000-05-31 | 2002-02-19 | Fbc Technologies, Inc. | Fluid flow system for floating biological contactor |
| US6322055B1 (en) | 2000-10-02 | 2001-11-27 | Eco-Oxygen Technologies, Llc | Gas dissolving apparatus and method |
| US6668556B2 (en) | 2002-04-18 | 2003-12-30 | Eco Oxygen Technologies, Llc. | Gas transfer energy recovery and effervescence prevention apparatus and method |
| CA2512783C (en) * | 2003-01-06 | 2012-10-02 | Tvt Us Corporation | Process for treating a body of water |
| US7566397B2 (en) * | 2004-02-09 | 2009-07-28 | Eco Oxygen Technologies, Llc | Superoxygenation of raw wastewater for odor/corrosion control |
| US7320749B2 (en) * | 2004-02-09 | 2008-01-22 | Eco-Oxygen Technologies, Llc | Method and apparatus for control of a gas or chemical |
| US10486120B2 (en) * | 2017-04-12 | 2019-11-26 | John T. Vlahogeorge | Floating horizontal aerator for a body of water |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE455656C (en) * | 1925-01-18 | 1928-02-07 | Constantin Weber Dr Ing | Crane scales with rope weight compensation and locking device, which only allow weighing if certain conditions are observed |
| GB587400A (en) * | 1943-04-21 | 1947-04-24 | Infilco Inc | Improvements in or relating to process of and apparatus for treating sewage and other waste liquors |
| US2822329A (en) * | 1955-08-30 | 1958-02-04 | Llewellyn B Griffith | Aquatic pond |
| DE1609016A1 (en) * | 1965-01-28 | 1969-11-06 | Volkmann Dipl Ing Fritz | Method and device for the biological purification of fluids by ventilation |
| US3371033A (en) * | 1965-08-11 | 1968-02-27 | Fmc Corp | Method of treating sewage and apparatus therefor |
| US3671022A (en) * | 1969-10-06 | 1972-06-20 | Air Reduction | Method and apparatus for the microdispersion of oxygen in water |
| US4148726A (en) * | 1973-01-08 | 1979-04-10 | Smith Kenneth C | Process for treatment of sewage in a gravity sewer |
| GB1513857A (en) * | 1974-04-08 | 1978-06-14 | Boc International Ltd | Treatment of sewage |
| BE819769A (en) * | 1974-09-11 | 1974-12-31 | DEVICE FOR PURIFICATION OF POLLUTED WATER. | |
| CH610870A5 (en) * | 1975-11-11 | 1979-05-15 | Gianmaria Righetti | |
| DE3026519C2 (en) * | 1980-07-12 | 1984-05-30 | WSW Planungsgesellschaft mbH, 4355 Waltrop | Facility for the regeneration of silted water |
| US4514343A (en) * | 1982-09-29 | 1985-04-30 | Air-O-Lator Corporation | Aspirating horizontal mixer |
| JPS60216898A (en) * | 1984-04-13 | 1985-10-30 | Nippon Kokan Kk <Nkk> | Apparatus for purifying water in closed water basin |
-
1989
- 1989-04-11 DE DE19893911789 patent/DE3911789A1/en not_active Withdrawn
- 1989-11-20 ZA ZA898818A patent/ZA898818B/en unknown
-
1990
- 1990-03-21 CA CA 2050885 patent/CA2050885A1/en not_active Abandoned
- 1990-03-21 AU AU52846/90A patent/AU632551B2/en not_active Ceased
- 1990-03-21 WO PCT/DE1990/000214 patent/WO1990011971A1/en active IP Right Grant
- 1990-03-21 ES ES90904757T patent/ES2043364T3/en not_active Expired - Lifetime
- 1990-03-21 DE DE9090904757T patent/DE59001866D1/en not_active Expired - Fee Related
- 1990-03-21 JP JP2504876A patent/JPH04504374A/en active Pending
- 1990-03-21 EP EP19900904757 patent/EP0467896B1/en not_active Expired - Lifetime
- 1990-03-21 BR BR9007285A patent/BR9007285A/en not_active Application Discontinuation
- 1990-03-21 US US07/768,191 patent/US5294340A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| AU632551B2 (en) | 1993-01-07 |
| WO1990011971A1 (en) | 1990-10-18 |
| AU5284690A (en) | 1990-11-05 |
| EP0467896A1 (en) | 1992-01-29 |
| DE59001866D1 (en) | 1993-07-29 |
| BR9007285A (en) | 1992-03-17 |
| ZA898818B (en) | 1991-12-24 |
| JPH04504374A (en) | 1992-08-06 |
| DE3911789A1 (en) | 1990-10-18 |
| ES2043364T3 (en) | 1993-12-16 |
| EP0467896B1 (en) | 1993-06-23 |
| US5294340A (en) | 1994-03-15 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |