DE2333675A1 - PROCEDURE FOR BIOLOGICAL PURIFICATION OF WASTEWATER AND SYSTEM FOR CARRYING OUT THIS PROCESS - Google Patents

Description

Nuremberg, July 2, 1973

PATENT ADVOCATE

. BERNHARD RICHTER
85NuRNBERQ Spittlertorgraben 27 Telephone £ 6 3067

AKVADAN A / S / Krogshflvej 29, DK-288o Bagsvrerd, Denmark.

Process for the biological purification of waste water and installation for implementation

this procedure.

The invention relates to a method for the biological purification of waste water in a cleaning system with three containers, of which at least two serve alternately as a feed tank, and at least one as a clarifier, wherein Wastewater in the system continuously through air inlet elements with simultaneous circulation the wastewater is treated aerobically.

Such a procedure can be carried out in two different ways will. In one case, the same container is always used as a clarifier, while the other two containers are used alternately as feed containers, in the latter two containers the wastewater is treated aerobically by introducing air and circulating. One is sufficient to carry out this procedure relatively simple system by only having two of the containers with the air inlet and circulation required facilities are to be provided.

In the other case, a system is used where all three containers with the named facilities are provided, and the three containers according to a certain Scheme alternately as a septic tank, as a feed tank and as an aerobically working one Containers are used.

In these known methods, a purification of the waste water for organic substance content is achieved by breaking it down and settling in the septic tank precipitates as sludge, from where it is returned to the aeration tanks, and any excess can be removed.

After this treatment, the wastewater still contains inorganic ones Links.

The aim of the invention is to create a method of the specified type, by means of which the wastewater can also be cleaned for inorganic compounds, including in particular nitrogen compounds.

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Used to purify wastewater for both organic and nitrogen compounds it is known to treat wastewater as follows:

First, the wastewater is aerobic in an aeration tank Subjected to treatment, after which it is sent to a final clarification tank. From the After clearing the sludge, the sludge is returned to the aeration tank while the water is led to another aerobically working aeration tank, where an oxidation of the nitrogen compounds to nitrate (nitrification) by microbiological Action takes place. After this aeration, the water is led to a secondary clarification tank and from there to a third tank, in which an anaerobic one Treatment carried out with the simultaneous addition of a nutrient for microorganisms which reduces the nitrate to free nitrogen (denitrification), and the waste water from the last container is finally turned into a secondary clarification tank out, from which the purified wastewater is taken. The mud from the latter The secondary clarification tank is returned to the denitrification tank.

This subdivision into three levels is made to ensure that the right microorganisms take effect at every stage, u.zw. in the first stage for the degradation of organic matter content, in the second stage for nitrification, and in the third stage for denitrification. For this process, three tanks, each with a subsequent secondary clarification tank, are required, and that Wastewater should pass through these six structures in sequence.

In an effort to simplify such a system, it has been attempted to to build an experimental plant (Wuhrmann), in which the wastewater is transferred to a first container is conducted by working aerobically to induce nitrification. From there the wastewater is led to another container in which it is anaerobic work is carried out to free nitrogen from the nitrate formed in the first-mentioned container to reduce, whereby the sludge in the second container mineralizes at the same time which supplies the energy necessary for denitrification. However, this simple procedure has only succeeded in a few cases, which is presumably due to it related to the fact that the energy source for denitrification is solely sludge mineralization is. The system is, however, simple to the extent that only two tanks connected in series and a final clarification tank connected after the last tank are required, from which latter the excreted sludge to the first Container is returned.

3Ö9884 / 1 11 1

The inventive method is characterized in that a Container that acts as a supply container during a period, at least during part of this period is operated in such a way that only one circulation of the wastewater takes place under substantially anaerobic conditions, and that this container at least during said part of said period with the as Clarification tank serving container is indirectly connected, u.zw. about the not as Effective septic tank, a tank is operated aerobically after an anaerobic period of operation in it before it is used as a septic tank or with is connected to a tank working as a septic tank. This achieves that it will be possible to use the previously mentioned systems for the biological purification of Waste water for organic matter in addition for the removal of a satisfactory Proportion of the nitrogen compounds contained in the wastewater to use .. The Invention is based on the knowledge that mixing of the for the degradation of the organic substance content, used for nitrification and denitrification different microcultures does not play an essential role, at the same time it was recognized that the anaerobic treatment of the wastewater with simultaneous supply of fresh wastewater satisfying the microorganisms used for denitrification Conditions. In this context, attention is drawn to that because at least two tanks are used alternately as feed tanks and between these periods for aerobic treatment, is in one as Supply tank effective container a very large proportion of wastewater is available, that in a previous stage of the operation of an aerobic treatment and thereby a nitrification was subjected, so that the nitrates formed by it intended microorganisms can be reduced at the same time by the undegraded material with which the wastewater supply is at issue Container enriches these, are supported in their growth. In addition, that the good biological cleaning effect of the known systems is maintained as well as the ratio that the containers continuously work with the same degree of filling, in that each container always delivers the same degree of liquid and receives. Because a container operated aerobically after an anaerobic period of operation before it is used as a septic tank or with one that works as a septic tank If the container is connected, there will be a breakdown of undegraded organic compounds ensured.

5 09884/1111

-A-

If a method is chosen in which a feed tank is only used during part of the period where it serves as a feed tank is working anaerobically this container according to the invention expediently during the last part of the period anaerobically and aerobically during the first part of the period during which the other two tanks, which do not work as a clarifier during the said first part of the period, are operated aerobically. Through this type of execution of the process is achieved that the largest possible for denitrification Proportion of nitrified nitrogen compounds is available. There Furthermore, the one of the two other tanks that does not work as a clarifier during the first part of the period is aerobically operated, becomes one for the Wastewater as a whole achieved favorable long-term aerobic treatment.

According to the invention, the supply container during the first part of its aerobic period with a tank working as a septic tank immediately, and during the latter part of its aerobic period as well as during its anaerobic period it must be connected to the clarifier via the third tank.

The invention also relates to an installation for carrying out the method with three containers, of which at least two with facilities for alternating Supply of waste water, and at least one with an outlet for purified waste water are connected, which system is characterized by the fact that the input ~ directions for introducing air into the wastewater and circulating the same so arranged are that they can be switched between two types of operation, u.zw. one where they both introduce air into and circulate the water, and one where they are in essentially just circulate the water. A particularly simple embodiment of this system is characterized in that the devices consist of paddle rotors exist, the speed of which is adjustable.

The invention is explained in more detail below with reference to the drawing will. Show on this

1-6 show an embodiment of the wastewater treatment plant according to the invention in six different operating positions to explain the method according to the invention,

7-12 a second embodiment of the wastewater treatment plant according to the invention in six different operating positions, and

13-18 a third embodiment of the waste water according to the invention

309884/1111

cleaning system also in six different operating modes.

In Figs. 1-6, 1 and 2 denote two containers, each in the shape of an oval open channel. This includes a secondary clarification tank 3 with a sludge scraper 4.

In each container 1 or 2, a rotor 5 or 6 is provided, which is at its circulation circulates the water in the two containers in the direction of the arrows. Each container 1 and 2 has an overflow 8 and 9, which is raised and can be lowered. The overflows are through lines Io and 11 with the Clarification tank .3 connected. Each container 1,2 is of a building 12 with Sewage supplied.

The rotors 5 and 6 are provided with drive means, not shown, which Can be adjusted so that the rotors either only hold the water in the container in question circulate or whip air into it. In the former case the container in question works anaerobically, and in the latter case aerobically. To illustrate on the drawing to what extent in the various operating states one or the other is the case, a rotor is if it just circulates the water, shown with blades or paddles protruding only in one direction, see FIG. 5 in Fig. 1, while a rotor, which both circulates the water and whips in air, is shown with blades protruding in both directions, see FIG. 6 in Fig. 1.

The installation also has a channel system, which is designated as a whole by 14 is and the secondary clarification tank 3 with each tank 1 or 2 for return of mud connects. The two containers 1 and 2 are through a transfer channel! 15 connected to each other, which is used to illustrate the operating states where an overflow from one container after the other takes place an arrowhead is shown in the direction of flow. The septic tank 3 is with provided a drain 16 for clarified water.

In Fig. 1, a state is illustrated where the waste water to the container 1 is supplied, the rotor 5 only circulates the water present therein, so that the Container works anaerobically. The overflow 8 of the container 1 is raised, and the Overflow 9 of the other container 2 is lowered so that an overflow takes place through the transfer channel 15. The rotor 5 in the container 2 also works full speed, i.e. aerobic, and over the lowered overflow 9 and through

309884/1111

the line 11 is provided with a connection to the secondary clarification tank 3. This condition lasts one hour as indicated by the times and is the last operating status before the wastewater supply to the tank was changed over 2 takes place.

During the operating period illustrated in FIG. 1, a anaerobic treatment of the wastewater, with denitrification taking place, as explained earlier.

After one hour, a changeover to that illustrated in FIG. 2 will occur Operating state made in that the waste water supply 12 to the Container 2 switched and at the same time the speed of rotation of the rotor 5 increased so that there is an aerobic state in the container 1. There won't be any made further changes so that both containers 1 and 2 are now ready for dismantling of organic matter and for nitrification work aerobically. This operating state takes half an hour, after which a changeover to that illustrated in FIG. 3 Operating state takes place in that the overflow 9 is closed and the overflow 8 are opened, whereby the supply to the secondary clarification tank 3 is now through the line Io takes place. At the same time there is an overflow from the container 2 to the container 1 through the UeberfCJhrungskanal 15. In this state is still in both Containers worked aerobically, so that a breakdown of organic matter and a nitrification takes place.

After the operating state illustrated in FIG. 3 half an hour has lasted, there is a changeover to the operating state illustrated in FIG. 4, by reducing the speed of the rotor 6 in the container 2, so that now anaerobically in this container for denitrification of the previously nitrified wastewater is being worked on. During this operating period, which lasts one hour, will the wastewater passed to the container 2, so that the freshly supplied wastewater the anaerobically working microorganisms in the wastewater in container 2 nourishes. From the in The operating state illustrated in FIG. 4 changes to that illustrated in FIG. 5. The operating state changed by switching the waste water supply 12 to the container 1, and the speed of the rotor 6 is increased to full speed so that im Container 2 is worked aerobically. The flow path to the secondary clarification tank 3 is not changed, so that in the course of the half-hour operating period according to FIG aerobic treatment of the water takes place in tank 2, in that in the previous one

309884/1111

Period was worked anaerobically. The denitrified ones are now removed Connections from tank 2.

After the half hour mentioned, the one shown in FIG The operating mode is switched by lowering the overflow 9 and the overflow 8 be raised, after which the now aerated water can begin in container 2, to overflow into the Nachkjdfrbehälter 3, u.zw. with aerobic degradation of organic matter Substance in container 1. After another half an hour, the in Fig. 1 switched operating state shown by the speed of the Rotor 5 is reduced, whereby anaerobic treatment and denitrification in the container 1 begins, as illustrated in FIG. 1.

It follows from this that one container is used as a supply container for two hours is used, after which the other tank serves as a feed tank for two hours, and during the last hour of such a feed period the in Question standing feed tank anaerobically while serving for the remaining three hours works aerobically for the entire four hour operating cycle period. Furthermore, the wastewater is treated aerobically before it is transferred to the secondary clarification tank 3 Each container takes in an amount of wastewater that is equal to that of the system during the course of the process corresponds to the amount of wastewater fed in for 12 hours.

The system shown in Fig. 7-12 consists of three assembled oval ones Containers 21, 22, 23, each having a central guide wall 21a, 22a, 23a, similar how. for the two containers 1 and 2 in Fig. 1-6.

In each container there is a rotor 24, 25 and 26, respectively, and the two Outer containers 21 and 23 each have an adjustable overflow 27 and 28 with an associated drain. Furthermore, the two outer containers 21 and 23 are provided with transfer channels 3o and 31, respectively, are connected to the middle container 22. The wastewater is supplied from a convertible structure 29, which is used for the supply of wastewater can be switched between all three containers.

In Figs. 7-12, rotors 24, 25 and 26 have the same symbols as used in Fig. 1-6, the only difference being that a non-rotating rotor is used as the a mere line is shown, see the rotor 26 in Fig. 7, where the container 23 as Clarifier works.

The system shown in Fig. 7-12 works as follows:

309884/1111

In the operating period of one hour illustrated in FIG. 7, works the container 21 as a feeder, and at the same time its rotor 24 runs with a lowered position Rotation speed around so that you work anaerobically. Furthermore, the overflow 27 of the container 21 is raised, while the overflow 28 of the container 23 is lowered, so that from the latter container - which works as a clarifier - what As mentioned, it is indicated by the fact that its rotor 26 is shown as a mere line is - there is an outflow. There is thus an overflow in series from the container 21 to the container 22 and further to the container 23 through the transfer channels 3o and 31, as indicated by arrows. Denitrification takes place in the container 21, in the container 22 a decomposition of organic matter and a nitrification.

After an operating period of one hour, the one illustrated in FIG. 8 is switched to Operating mode changed by placing the inlet 29 on the middle container 22 is switched, and the rotor 24 is switched to full speed, so that the anaerobic state in the container 21 is replaced by an aerobic state for the purpose of ventilation before clarification. The middle container 22 works to break down organic Substance and nitrification. The outer container 23 still works as a septic tank, and only water is passed to him, one denitrification and one on it has been subjected to the following ventilation. After an operating period of one half an hour is switched to the operating state shown in Fig. 9, where the Supply of sewage is maintained, but at the same time the rotor 24 is stopped, so that an incipient clarification takes place in it without agitation. After a half Hour is switched to the operating mode illustrated in Fig. Io, where the sewage supply is switched to the container 23, the overflow 28 of this container is closed, whereas the overflow 27 of the container 21 is opened, and the Rotor 26 is started to reduced speed, so that in the container 23 to Denitrification is worked anaerobically. This mode of operation lasts an hour, after which is switched to the operating mode illustrated in FIG. 11 in that the Rotor 26 is brought to full speed, so that in the container 23 a ventilation of the Water takes place. After half an hour, the one illustrated in FIG. 12 is shown The operating state is changed by stopping the rotor 26, so that the container 23 can continue to operate for the half-hour period of this operating period Clarification tank initiates, including by resetting to that illustrated in FIG. 7 State is switched.

3GÖ884 / 1 11 1

In the system shown in Fig. 7-12, a container then begins to work anaerobically when used as a feed tank.

In the systems explained so far, rotors with protruding blades are used or paddling used as both circulation members and ventilation members by the full speed both effects, * the reduced speed on the other hand only circulation drive over.

The invention, however, is not based on the use of the same easily convertible facilities for generating these two functions limited, although this achieves a simple structural design.

As shown in Fig. 13-18, the invention can also be implemented in systems where separate circulation devices in the form of stirrers, and devices that cause both ventilation and circulation, u.zw. by the Blowing in air, are provided.

In Figs. 13-18, 31 and 32 denote two containers each with air injection members 33 and 34 and a stirrer 35 and 36 are provided. Apart from that of which the system is arranged in the same way as the system according to Fig. 1-6, by having a secondary clarification tank 3 to which lines Io and 11 lead, wherein the container 31 and 32 each have an overflow 8 and 9 and through one Transfer channel 15 are connected to one another. There is also the secondary clarification tank 3 is connected to the two tanks 31 and 32 via a sludge return system 14.

The plant in Figures 13-18 is. symbolized analogously to the other systems, in that it is indicated by arrows when an overflow through the transfer channel 15 takes place, and it is also noted by arrows when the supply to the secondary clarifier through one or the other of the lines Io and 11. Further circulation or anaerobic treatment is indicated by showing the stirrer of the container in question, whereas aerobic treatment is symbolized by it it is shown that the air injection members of the container in question 33 and 34, respectively are which members simultaneously bring about an overturning.

Since in the system according to FIGS. 13-18 the subdivision of the entire operating cycle is exactly the same as in FIGS. 1-6, a more detailed explanation is superfluous by adding the symbols are sufficient for explanation.

For all systems it also applies that water always has the same amount flows from a container and is fed to this, so that with approximately constant filling of the container is used.

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Claims (5)

Ρα tent claims: M ^ Process for the biological purification of wastewater in a purification plant me three bins, at least two of which alternate as feed bins, and at least one serving as a Klifr tank, with wastewater in the plant is continuously treated aerobically by air inlet members with simultaneous circulation of the wastewater, characterized in that a container, the serves as a supply tank during a period, is operated at least during a part of this period in such a way that only a recirculation of the wastewater under it essentially anaerobic conditions takes place, and that this container at least during the mentioned part of the mentioned period is indirectly connected to the container serving as a septic tank, u.zw. over the not as a septic tank effective container, with a container after an anaerobic period of operation therein operated aerobically before being used as a septic tank or with one as a septic tank working container is connected. 2. The method of claim 1, wherein a feed container only during anaerobic for part of the period during which it acts as a supply reservoir works, characterized in that this container during the works anaerobically during the last part of the period and aerobically during the first part of the period, and that that of the two other containers which does not function as a clarifier during said first part of the period is operated aerobically. 3. The method according to claim 2, characterized in that the feed tank during the first part of its aerobic period with an as Septic tank working tank immediately, and during the latter part of its aerobic period as well as during its anaerobic period via the third tank is connected to the septic tank. 4. Plant for performing the method according to claim 1 with three Containers, at least two of which have facilities for alternating supply of wastewater, and at least one connected to a drain for purified wastewater are characterized in that the devices for air intake, management in the wastewater and for circulating the same are arranged so that they can be switched between two operating modes, u.zw. one where they both air in that Introduce water and circulate it, and one where they basically just circulate the water. 309884/1 Π 1 * 5. Plant according to claim 4, characterized in that the facilities consist of paddle rotors, the speed of which is adjustable is. 309884/1 1 1 1 it Blank page