LT3791B - Method for biological treatment of waste water - Google Patents

Abstract

The biological treatment of effluents is effected by several parallel chains of aerators, suspended from air hoses, if necessary with a carrier wire, across the basin. The aerators are located near the bottom of the digested sludge basin and are oscillated when supplied with compressed air. Only a part of the chains receive the full air supply at a time; the others are more or less cut off so that only the former produce a through circulation of sludge and effluent. The active part of the chains is changed in such a pattern that a migrating wave is generated across the basin.

Description

The present invention relates to the field of advanced biological treatment of wastewater.

Approved VFR Application No. No. 2834899 discloses a method of biological treatment of wastewater using a plurality of distant, suspended and movable circuits on the surface of the water, with aerators performing uniform aeration over a large area, as well as agitation of activated sludge from the effluent. These devices are characterized, for example, by the fact that spacious, primarily shallow, aerial tanks allow the management of low-load sewage treatment with activated sludge without the mechanical mixing of the aerotank contents.

This means that the control of the various conditions of the activated sludge in the aerial tank can be achieved at any time with relatively low energy consumption.

In known activated sludge treatment plants, for aeration and mixing, air is fed into the aerotank simultaneously in all bottom aerator operating ranges to achieve a uniform air supply over the entire length of the aerotank. The fluctuating movements of the chains with the aerators ensure that the activated sludge does not settle at any point for undesirable changes.

Bottom-reaching bottom aerators, which, in a known device, slide the entire bottom of the aerotank in a sliding motion, pick up the activated sludge, screw it in and out of the appropriate bottom with a rising stream of water and air.

Despite the relatively low specific energy consumption for mixing, in this system, during low loads, such as at night, at the end of the week, etc., the energy used for mixing may be more than necessary or sufficient to supply oxygen; which leads to an undesirable amount of oxygen in the aerotank, i.e. y. to undesirable effects on the cleaning process.

The wastewater treatment plant operating with bottom-mounted aerators permanently mounted on the bottom of the air tank and having nozzle-like devices for mixing the sludge with the wastewater belongs to a group of high-load units with a main energy consumption of 10-15 W / m. In addition, they provide a horizontal, well-secured bottom for the aerotank so that the power nozzle can be positioned horizontally. This arrangement allows for an even air supply. Attempts have been made to operate the pe20 in such devices by supplying air through separate fixed mounted aerators. The first tests were conducted in 1915, confirming this

British publication no. 1141. The most recent efforts in this direction are described in European patent application no. 0145647. But there are various problems with such devices. One of the fundamental problems is that fixed aerators tend to become clogged, and this is particularly pronounced when such devices, for example, operate in intermittent mode. In addition, when the unit operating with stationary aerators becomes clogged, it can only be cleaned by completely disconnecting and draining the water from the aeration tanks. This results in device downtime and high costs. In addition, not only bottom aerators, but first and foremost among these aerators, sludge is deposited throughout the disconnected bottom aerators, which, even when switched on, no longer returns to the circulation state - may lie dormant and may have very negative effects. affect or paralyze the whole process of sewage treatment with activated sludge.

Various devices are known for carrying out certain special processes, such as dentrification. For example, a special pre-dentrification air tank and its operation are known. It is also known to interconnect a number of staggered aerial tanks so that the individual aerial tanks can perform the required partial cleaning process modes. It is also known to realize such purification processes in one annular canal-shaped aerotank, which circulates water and forms various zones.

In an area where oxygen is depleted, the impeller is fitted. Such aero-tanks shall operate at a flow rate of at least 0,3 m / s.

On the contrary, it is an object of the invention to provide a method that can be adapted to any, even changing requirements, and improved wastewater treatment process, preferably in lightly loaded underground aerosols.

This problem is solved by the biological treatment of wastewater by initially attaching, on the surface of the aerotank, surface-spaced chains of aerators, each carrying a plurality of chain-mounted aerators at a certain distance from the base of the aerator during operation of the chain-aerators. slides back and forth, causing the bottom aerators to periodically slide over the bottom of the aerotank, then for aeration and mixing the effluent with the activated sludge, at certain times only a certain proportion of the total number of circuits with the aerators is fully air-fed the feed to other aerator circuits is throttled, resulting in complete mixing of the effluent with activated sludge in fully air-saturated areas, followed by complete air supply to other aerator circuits at intervals, the waveform from one to the other, not the total number of circuits with the aerators.

The present invention provides a method of wandering the air into separate circuits with aerators, whereby the aerators overhang themselves, causing a wave (or several waves) of intense aeration zones to pass through the aerotank and, on the other hand, creating wandering, much weaker or non-aerated fields. . Thus, waves are constantly wandering in the air tank, and the technological step, which is achieved by a certain state of the wandering zones, is continuous, and when summed up, it gives the full realization of this technological step. Thus, for example, one aerotank having a high efficiency can achieve a simultaneous denitrification effect by continuously passing through the aerotank the zones causing denitrification. By combining the wandering movement of the bottom aerators, on the one hand, with the periodic supply of air to separate aerator circuits, on the other hand, the combination creates a technological mode with great technological advantages. These advantages are achieved by the fact that purposeful special technological regimes can be realized by delivering small amounts of oxygen, for example 0.3 mg oxygen per liter from the maximum value. This increases the operational reliability of the unit. The creation of these wandering zones and the possibility of creating them by using special technological regimes, despite the possible small amount of usable oxygen, can be realized without impeller. Such very precise narrow zones can be formed because mixing is done in a very well defined vertical zone that can pass anywhere in the aerotank. Conversely, mixing and expansion in the horizontal direction does not occur. This creates very precise and only slightly horizontal areas, which can then be displaced anywhere in the air tank due to their displacement. At this point, the water flows perpendicularly to the zones. The occasional repositioning of the individual drum aerators causes the latter to self-purify as the sludge that settles on the individual bottom aerators in their dormant state is washed away during the repositioning of those aerators. Therefore, despite the disconnection of the individual bottom aerators, these aerators are not completely clogged.

The present invention provides a combination of, firstly, the use of movable circuits with suspended aerators for aerating and mixing them, and secondly, the use of only a limited number of circuits with aerators during full air supply, respectively selecting the rotating wandering mixes and the supply air. quantity intervals, provides variable technology mode.

Operated in this way, for example, during low loads, incomplete sewerage networks, growing settlements, during night hours or during holidays, can always ensure a technologically optimized mode of operation.

The method of the invention is also utilized in the knowledge that it is possible to allow, at certain intervals, a partial reduction or desirability of the activated sludge or said sludge in the bottom areas of the aero tank, whereby no oxygen is supplied to these areas. It has been found that as long as the time intervals are maintained, these zones, although not receiving oxygen, do not lose their significance, meaning that they do not lose or lose their vitality, but, on the contrary, they stimulate greater cleaning performance, i.e. higher degree of nutrient degradation. The sliding bottom aerators periodically wander over the bottom of the air tank, guaranteeing that the entire bottom of the air tank will be covered by aerators at fixed intervals so that even when deposited anywhere in the air tank, the sludge will be continuously raised and incorporated into the mixing process. Therefore, the loss of viability of the sludge in any area of the bottom of the aerotank, which occurs with the use of stationary bottom aerators, will not occur by the methods of the invention. Compared to devices operating with fixed bottom aerators, the proposed method provides a number of essential advantages in that it is possible to perform processes that require lower oxygen levels. This cannot be achieved in units that operate only with fixed bottom aerators, since these units consume significantly more basic energy for mixing, so it is impossible to maintain the lower amount of oxygen required for these processes.

The supply of air to individual sliding circuits with aerators may be optimally coordinated and implemented as required, for example by delivering, for a predetermined period of time, air to each of two aerator circuits, separated by at least one non-aerated or lightly aerated circuit with aerators; so that each time, at predetermined intervals, air is supplied to adjacent circuits in the same direction with the aerators. If, for example, eight aerial chains with aerators are installed next to each other in the air tank, the air is fully fed to the first and fifth aerator circuits, and the rest are only slightly aerated or not aerated at all. Then, over a period of time, the air is completely fed to the second and sixth aerator circuits, and the remaining aerator circuits, such as the first and fourth circuits, are switched to reduced air supply or shut off completely. This is continued until finally the fourth and eighth circuits with aerators form intensely aerated zones at their respective locations. Then restart the first and fourth circuits with aerators and so on.

Depending on the number of existing aerator aerial chains, depending on the dimensions of the aerator, after loading or in particularly heavy sludge, for example, two adjacent aerator chains (a pair of aerators), as well as a series of aerator chains, aerators for a pair separated from the first pair by a number of air-tight or poorly powered circuits with aerators. The wandering mixing of the aeration zones, which results in the sliding of the individual circuits, is then accomplished by disconnecting each pair of aerator circuits each time and connecting one circuit with the aerators on the other side of the circuit, which is still fully powered by air.

It is also permissible to supply air only to a specific part of the aerotank by wandering, so as to maintain continuous or temporary uninterrupted feeding in the remaining parts. It is also possible to supply air to different areas of the aerotank at different frequencies according to time or at different intensities. This may be appropriate, for example, when the air tank is to be continuously or temporarily completely filled with air at the inlet, while the remainder of the air tank is supplied with air at a rapid, rapid rate. In order to ensure a steady supply of oxygen to or from the inlet or outlet of the aerotank, the aerators belonging to that zone shall be supplied with air either wholly or temporarily without interruption, and the remainder of the aerotank shall operate in one or more variable modes.

The skilled artisan will appreciate that the new approach with sliding and, in addition, wavy-powered circuits with aerators, goes beyond the described examples and provides a major advance in controllability, alignment, and fine tuning through the biological mode process, as new aeronautical modes emerge , which cannot be achieved by means of the prior art using fixed bottom aerators. This means that, on the basis of a well-balanced activated sludge, there are possible variants of the method which can only be achieved with the low energy consumption of the devices described herein.

The time during which the air is fed to the circulating aero-aerators, and thus the crawl speed at which the aero tank is intense aeration zones, is adjusted to suit the oxygen content, loading and sludge characteristics. But the minimum velocity must still be high enough for the activated sludge particles to settle or not to settle on the bottom. In this way, optimal alignment can also be achieved with the appropriate sludge indicator, which expresses the weight of the sludge and the minimum amount of energy required to supply it each time.

Another advantage is that the number of air-powered sliding chains with aerators is controlled depending on the amount of oxygen loaded on the aerial tank and the characteristics of the sludge. Thus, the frequency of full loading of the aerator circuits, if controlled, for example, depending on the load, can always be optimally matched to the oxygen demand with minimal energy consumption. In many cases, it has been found that a wavy wandering speed at which each aerator chain is fully loaded, for example 1 to 10 times per second, is sufficient.

The most preferred embodiment of the method implies that the time intervals between the total air supply and / or the air filled circuits with the aerators are automatically adjusted from the parameters that determine the required oxygen supply, such as sudden loading and sludge volume. In order to realize such a controlled flow, various parameters can be measured during operation which determine the amount of oxygen required. For example, the amount of water flowing (m ³ / h) or the temperature (T) in the basin can be controlled by appropriate measuring devices. Metrologically, it is also possible, for example, to fluctuate pH values in run-off waters or components that absorb oxygen. It is also possible to measure, for example, an aqueous suspension. The results of these measurements can then be fed to a central computing machine unit, such as a computer, and processed accordingly, or automatically fed into separate aerator circuits, depending on the results of these measurements or a program tailored to the specificity of the wastewater or installation. Depending on the measurement results obtained, more oxygen can then be delivered to certain locations, such as the entrance area, or oxygen delivery devices can be transferred to the aerotank faster. All this ensures the optimum operation of the unit every time, which, thanks to the lazy performance of the process, enables the optimum treatment of wastewater every time.

Yet another preferred embodiment of the method implies that the amount of oxygen supplied to a given number of sliding aerators filled completely with air would be greater than that provided with the same number of circuits if all the chains of aerators were completely filled with air. This means that the amount of exhaust air per aerator circuit according to the method according to the invention may be higher than in a device where all aerator circuits operate simultaneously. Suppose a conventional device has ten aerator circuits that are simultaneously loaded on all.

In the method of the invention, the load is initially reduced overall, for example by 50%. But the amount of air is not divided between the five aerator circuits, but only, for example, the two circuits, so the air supply will increase significantly. In the extreme, this amount is fed to only one aerator circuit, for example, for a short time. This concentrated air supply has many advantages. First, it can, for example, dissolve the sludge islands in the pond. For example, with 10 aerator circuits, concentrate a single aerator circuit with 10 times the amount of supply air that actually reaches anywhere on the bottom by shifting individual circuits and sequentially switching to each individual circuit. Second, the individual bottom aerators, based on a specific, occasional air supply, combined with the cleaning effect achieved by shifting, remain clogged because they are constantly inflated by increased outgoing air or sliding very quickly and are thus affected by the flow of water. The local increased air supply to the individual sliding circuits of the aeraLT 3791 B leads to relatively large amplitudes which intensify sludge mixing. Intensive accumulation of sludge sediment in the bottom, for example, after a long power outage or other downtime (exploration work) or after heavy sludge feed, etc., can concentrate the entire air potential of the unit in a few rows of sliding aerators. large amount of air. This results in a wandering pseudomorphic and turbulent wave in the aerotank, which, through the simultaneous sliding of the circuits, covers the entire bottom after a period of time, and the unit returns to normal.

The device for implementing the method of treating sewage sludge with activated sludge in each ducting line is characterized in that the air of the laying aerator circuits is equipped with a centrally controlled throttle valve which regulates the throttle or closes the air supply to the respective air supply line. Such a throttle valve, which is mounted in each air supply line, allows the air to be individually fed into and shut off or throttle the individual air supply lines of the sliding circuits with the aerators. An individual control is made, and at the same time such control can be implemented by a central control unit, which can be set alternately for time intervals and for the number of fully loaded sliding chains with aerators. The resulting high flexibility in frequency and volume of airflow at the lowest energy consumption allows for flexible adaptation to a wide variety of loads and excellent control in a variety of specific technological conditions and variants, particularly with activated sludge treatment.

Controllability is understood herein as, for example, the fine-tuning required in the particular technological states mentioned above. Such fine-tuning with fixed bottom aerators is, in principle, impossible because the required initial pressure cannot be maintained.

In a wastewater treatment plant, the water level is always fluctuating and the bottom has irregularities that can only disappear after long settlements. Thus, in fixed bottom-mounted aerators, the initial pressure fluctuates, varying with water level or bottom condition. For example, it would be uneconomic to have a separate impeller for each row of aerators to work at an even starting pressure. When using floating and sliding aerators, the latter always stay at the same level regardless of the water level, since the distance from the water surface always remains constant. Unexpectedly, the preconditions for fine-tuning and, at the same time, opportunities for the realization of special technological states are created in a simple way.

In a particular embodiment of the invention, each air supply line is formed by a hose tube and the throttle valve is in the form of a pressure valve. The pressure valve can be loaded with, for example, a pneumatic piston. The individual pressure relief valves can be controlled, for example, by means of a central compressed air line and the corresponding valves. A pressure relief valve of various loads reduces the cross-section of the flow in the hose pipe, thus achieving the required throttling of the supply air in a very simple way.

Throttle valves, together with the control unit, can also be retrofitted to existing units, so that existing units can be easily adapted to the method of the invention.

It can be useful that the air is never completely interrupted to the fully loaded aerator circuits to prevent the bottom aerators from clogging. When light loads are maintained on non-fully loaded aerator circuits, the outgoing air bubbles prevent the aerator circuits from clogging. In this case, it is useful to install a rigid small-diameter tube at the point of impact of the pinch valve inside the hose tube, so that the pinch valve will never be able to close the hose tube completely with this tube.

The method of the present invention can be most conveniently used in so-called pond installations or in aerial circuits for aeration of lakes and other bodies of water by floating, suspended on floats.

The invention is further described and explained in the drawings below.

FIG. 1 is a schematic top view of an aerotank with sliding aerator circuits;

FIG. 2 is a side view of a bottom aerator suspended on a float;

FIG. 3a-3c is a schematic representation of the loading of individual sliding aerator circuits at various time points;

FIG. 4 is a schematic top view of a device for regulating the supply of air to individual sliding aerator circuits;

FIG. 5 is a longitudinal sectional view of an embodiment of a squeeze valve;

FIG. 6 shows the whole scheme of the method.

FIG. 1 is the only aerotank for a sewage treatment plant, collectively designated 1, which may consist of a number of such aerotanks, as well as other tanks and settlers. The effluent to be treated is fed through the feed line 2 to the aerotank 1 and then discharged from the aerotank via the opposite side discharge unit 3. The said water can then be transferred to another aerotank for treatment with activated sludge or a sludge tank. In addition, it is possible to foresee transfusion lines for sludge, which always depends on the specialization unit that implements the cleaning method. In connection with the fact that the invention can also be used in pond devices which operate without sludge and in activated sludge treatment devices, some details of the device are omitted in this embodiment.

To enable the treatment of waste water, it is necessary to mix these waters with activated sludge at each aerotank site and to ensure contact with the water being treated after oxygen has been applied.

To this end, in the present embodiment of the cleaning method above, eight floatable aerator chains 411 are mounted on floats, each carrying separate bottom aerators 12 spaced apart (see Fig. 2). Each of the individual circuits with the aerators has a flexible hose tube 14 which extends to the area of the floating bottom aerator 12. Said pipe is connected to the bottom aerator by a horizontal upper part 15 of the connecting pipe 16. This part of the pipe is inserted at opposite ends into both parts of the hose pipe 14 of the adjacent air supply line. At the lower end of the connecting pipe 16 is a distribution pipe 17 parallel to the holders, the surface of which has a plurality of holes 18 for the exit of air. Compressed air enters the distribution pipe through the air supply line 14 and the connecting tube 16, which then passes through the holes 18. In this example of a cleaning method, a float 13 is provided in the area above each bottom aerator 12, which passes in the longitudinal axis of the holder. for the aerator 12. The hose pipes and the bottom aerators are connected by means of conventional fastening devices such as presses 19.

In other embodiments of the invention, not shown in the drawing, flexible hose pipes may be used instead of a rigid connecting pipe, each of which connects the respective manifold 17 to the air supply line 14. Using a plurality of flexible lead hoses, e.g. has the advantage, especially of the proposed cleaning method, when the air is supplied individually to individual sliding bottom aerators, and the amount of transfer is greater than that of evenly distributed to many aerators. In parallel with the air supply line 14, a supporting cable can be attached above each aerotank, to which it is convenient to fasten the air supply line flexible pipes.

The individual aerator chains 4-11 are mounted above the aerotank 1 so that they float freely and, when air is supplied, said chains are displaced sideways. The floating aerator chains then move the bottom aerators 12 and begin to slide over the bottom of the aerotank, preferably at a very short distance from the bottom of the aerotank, for example 19-30 cm. These sliding, parallel movements of the bottom aerators achieve oxygenation in large areas and, for example, ensure that nearby aerial aerators re-lift and reintroduce activated sludge that has been partially deposited or deposited on the bottom of the aerial tank.

FIG. Figures 3a-3c show a cross-sectional view of a running device through Figs. 1. The first moment of time is taken, for example, the situation shown in Figs. 3a. At this point in time, as shown schematically in the drawing by arrows 20, the circuits with the aerators 4 and 5, as well as 8 and 9, are completely filled with air. Thus, at that point in time, only a fraction of the volume of the aeration tank is completely aerated, whereas at that time only a small amount of oxygen is delivered and a slight flow (dashed lines) occurs in the other volume of the aerator circuits 6, 7 and 10, 11.

After a set period of time, which depends, for example, on the load on the unit, the fourth and eighth circuits of the aerators are disconnected, and the sixth and tenth circuits are replaced. Aerator circuits 5 and 9 are completely filled with air as before. Thus, such a shift to the right results in a shift to the right, as shown in the drawing, and an area where oxygen is intensively supplied. At a later point in time (see Fig. 3c), the air supply to the fifth and ninth aerator circuits is switched off again and to the seventh and eleventh circuits. In the example shown in this example 17 each time, i.e. the air is always fed to two pairs of aerator circuits remote from each other. The new aerator circuit is connected each time in the direction of chain pairing, and in the example shown each time the aerator circuit is located to the right of the chain pair.

In this way, a wave of vigorous oxygen supply and / or vigorous stirring is generated, running from the left to the right in the example given in the aerotank. After the unit has been operating for a period of time as shown in Figs. 3c, resuming operation in the manner illustrated in FIG. 3a and so on. The essential point is that the air supply wave is modulated by all possible actuations in the sliding aerator circuits, since only the main effects achieved by the sliding of the floating aerators, especially the activated sludge, can achieve the special effects described in the invention only during operation.

It is clear that depending on the loading of the aerotank or depending on the technological effect attainable, the switching on and off can be done at various intervals. It is also clear that instead of simultaneously loading two pairs of aerator circuits, only two separate aerator circuits can be loaded each time, for example initially the aerator circuits 4 and 8, then the circuits 5 and 9, then the circuits 6 and 10 and finally the circuits. 7 and 11.

In units with a small number of aerators, such as only three circuits, it may be sufficient to only fully pressurize one aerator circuit each time with compressed air. It is also clear that entire areas of the aerotank can be loaded tightly or in a different rhythm.

A corresponding air supply control is schematically illustrated in FIG. 4. There is provided a central control unit 21 which loads the clamping valves 22 belonging to the respective individual aerator circuits 4-11.

The clamping valves affect the ends of the hose pipes 4-11, respectively, and reduce their average cross-section during loading. The throttle valve hose tubes are each loaded at full power provided by the compressed air supply 23. The pressure valves can also be loaded and operated with compressed air, for example. But it is also possible to use electric valves 22 and a central compressed air control station.

A specific example of a pressure valve that can be used to carry out a cleaning method according to the invention is illustrated in FIG. The clamping valve 22 consists essentially of a tubular rubber cuff 34 having an inner diameter approximately equal to the outer diameter of the hose tube 4. This cuff can be slid onto hose tube 4. The annular flange 32 mounted on the rubber cuff 34 such that a chamber 35 for receiving compressed air is formed around the cuff, the flange 32 has an element for connection to the compressed air conduit 33. Thus, after the flange 32 is sealed on the rubber cuff 34, a pressure P can be applied by applying compressed air through the coupling member 33, which will act on the rubber cuff 34 in the direction of the arrows and compress the hose tube 4. Inside the hose tube 4 on the drawing. a tube 36 inserted into the spacers not shown, which ensures that a minimum amount of air is passed even when the hose tube 4 is compressed in the extreme compression condition shown in dashes in FIG. 5.

Depending on the chamber pressure 35, different inlet cross-sections can be set.

FIG. 6 is a schematic diagram of a method embodiment.

Here again we see the aerotank 1, as well as the individual aerator circuits 4-9 arranged in the aerotank.

At each end of the slider aerator chain are pressed valves 22, which may be of the design shown in FIGS. 5. Outlet 1 of the air tank 1 has a sludge collection sump and an outlet 3. Return sludge R from the sludge collection sump 24 can be used to transport activated sludge to the inlet 2 to supply activated sludge to the inlet wastewater and domestic water.

The individual sliding aerator circuits 4-9 are connected to each other by a ducting compressed air line 25, and the separate pressure valves 22 are connected by hose pipes 25. Various compressors 23a-23c are incorporated in the hose line 25. These compressors carry the required air pressure and receive, by means of wires 26, 26a, 26b, extended from the cabinet 37 of the switchgear, the electrical current required for their operation.

Connecting wires for compressors 23c, 23d, and 23e to improve drawing visibility, not shown therein, are controlled by a control unit 21 having a counting device 21a, as well as a distribution unit 21b which can individually actuate each individual valve 22 depending on the command, taken from the counting device 21a. Only two pipelines 30 are shown in the drawing. However, each pressurized valve 3791 B is provided with a separate compressed air pipeline for individual actuation of the individual valves 22.

In addition, various measuring probes 27, 28 and 28a, 28b are incorporated in the aerotank. For example, probe 27 can continuously measure the oxygen content in the aerotank, and, for example, probe 28 can record water turbidity. The measuring probe 29, which is installed in the inlet 2, measures the amount of domestic and industrial waste water.

All recorded signals from these probes are transmitted to and processed by a computing device. The calculating device then transmits the respective signals to the distribution block 21b via a command transmission cable 38, which then individually loads the valves 22 with compressed air for the correspondingly received signals.

Of course, with a computing device, the device can operate under a rigorous program.

It has also been found that the treatment method of the present invention can utilize, for example, a sludge treatment plant with activated sludge at very low energy consumption compared to other plants of this type. Advantages of the invention occur, for example, in low-load devices. The sliding oxidation waves of the present invention, when combined with the wandering displacements of the individual aerator circuits, provide high flexibility and adaptability to a variety of load and technological situations, while allowing the unit to operate economically at all times. Typical oxidation wave creep rates, which provide oxygen at a ratio of 5: 1 or even 10: 1 compared to low aerated or non-aerated areas, are approximately 0.01-0.06 m / s. Specific air supply to intensely aerated areas can amount to 0.3 to 1 m air per m of water per hour, and as mentioned above, aeration can be 5 to 10 times less.

It has been found that once sedimentation occurs, the sludge settles extremely slowly (typical sedimentation velocities are 0.0005-0.003 m / s), requiring a relatively long time for the sludge to settle to the bottom. Then, if oxygen is applied to the bottom by appropriate oxygen aeration at 1 to 6 times per hour, this will be sufficient to maintain the activated sludge viability and will not cause loss of anaerobic zones throughout the aerial tank, although this does not eliminate the possibility of low oxygenation. Nonetheless, the unit can be operated, for example, as a controlled, well-controlled sewage sludge treatment plant with great advantages of variable processes and improved cleaning effect, while mixing the treated water in the aerotank volume requires significantly less than 3W per m ³ , is the minimum size for aerator chains with an even air load; this phenomenon was particularly unexpected given that purely surface aeration and fixed bottom aerators only use about 10 W / m ^{3 for} mixing.

By modifying the main motion of the floating circuits mounted on the aerator tank bottom aerators by the various load options described above, wave-sliding or zone-linked, it is possible first to achieve a more advanced treatment of the wastewater, e.g. simultaneous removal of nitrogen and phosphates in activated sludge (in one aerotank). Such opportunities are never achieved in simple low-lying aerial tanks and are widely considered impossible at present.

Claims (3)

Biological treatment of wastewater in an aerotank with bottom aerators distributed over it 5 circuits, the essence of which is that the aerator chains are provided with a sliding motion along their operating area and the air is supplied to the aerator tank via the aerator chains, which differs from that of the individual bottom aerator chains or chains. The 10 groups supply air at varying intensities and change the intensity of the air supply to the bottom aerator circuits at wavy intervals by successively switching the air supply to the adjacent bottom aerator circuits.