Treatment of sewage in a sewer

Abstract

The invention relates to a method for treating sewage (3) in a treatment portion (2) of a sewer (1), wherein, in the treatment portion (2), * gas bubbles (7) containing oxygen and / or ozone are introduced into the sewage (3) at a first introduction point (4), at least 50% of which gas bubbles have a diameter of at most 500 nm, and * the sewage (3) is then guided over at least part of a heat exchange device (8) and thermally treated in the process, wherein the heat exchange device (8) is spaced apart from the first introduction point (4) at a maximum distance of 5 m.

Description

[0001] Treating wastewater in a sewer

[0002] The invention relates to a method for treating wastewater in a treatment section of a sewer and to a corresponding sewer.

[0003] Due to climate change, the sewer system is subject to ever greater demands. Higher temperatures and prolonged periods of drought lead to increased bacterial activity and longer flow times for wastewater to reach treatment plants. This causes oxygen in the sewer to be rapidly depleted. The formation of hydrogen sulfide, in particular, can cause unpleasant odors. The formation of sulfuric acid can also lead to corrosion of the sewer structure.

[0004] For example, it's known from the state of the art to cool wastewater. For this purpose, the wastewater is passed through heat extraction elements at the bottom of the sewer. However, this quickly leads to contamination of the heat extraction elements, which reduces cooling efficiency. Such solutions are therefore not sufficiently reliable.

[0005] It is also known to condition wastewater by adding dosing agents. However, existing solutions for this are inefficient.

[0006] The object of the present invention is to treat wastewater in a sewer in a simple and reliable manner so that the sewer is protected and odor nuisance caused by the wastewater is reduced.

[0007] This object is achieved by the method and the sewer according to the independent claims.

[0008] According to the invention, a method for treating wastewater in a treatment section of a sewer is presented, wherein in the treatment section

[0009] ■ at a first point of introduction, gas bubbles containing oxygen and / or ozone are introduced into the wastewater, of which at least 50% have a maximum diameter of 500 nm, and

[0010] ■ the wastewater is then passed through at least part of a heat exchanger and thermally treated, the heat exchanger being located a maximum of 5 m from the first point of introduction. Any pipe that can carry wastewater can be considered a wastewater sewer. The wastewater sewer can therefore also be referred to as a sewage line. The wastewater sewer can be part of the public sewer network, through which wastewater from households and industrial establishments is transported to sewage treatment plants. The wastewater sewer is preferably suitable for installation underground. The wastewater sewer can be designed as a pressure pipe. The wastewater sewer can be designed as a gravity sewer.

[0011] However, the sewer can also be laid outside a main sewer and / or above ground, particularly in the area of ​​the treatment section. For example, wastewater can be pumped from an underground main sewer into the above-ground sewer with the treatment section and then returned to the main sewer. In this case, the wastewater is pumped to the sewer located outside the main sewer with the heat exchanger for thermal treatment, thermally treated with the heat exchanger, and returned to the main sewer after thermal treatment. In this case, it can be particularly advantageous to first filter the wastewater and then enrich the pumped water stream with nanobubbles using nanogenerators.Also, in general, the sewer described herein may be laid parallel to a main sewer so that wastewater from the main sewer can be diverted for treatment in the sewer and then discharged back into the main sewer.

[0012] The sewer is designed to transport wastewater. The nature of the wastewater is irrelevant for the functionality of the process. The wastewater can be, in particular, wastewater and / or rainwater. Accordingly, the sewer can be a wastewater sewer, a rainwater sewer, or a combined wastewater and wastewater sewer.

[0013] In the described method, wastewater is treated in the sewer. This takes place in a treatment section of the sewer. The treatment section is defined by the fact that the elements described herein for treating the wastewater are arranged within the treatment section. Furthermore, it is possible, but not required, for the treatment section to be different from the rest of the sewer.

[0014] The advantages described herein can be achieved if the sewer has a single treatment section. However, it is preferred that the sewer have multiple treatment sections. This is particularly useful for long sewers. For the sake of simplicity, the case of a single treatment section is discussed here as an example. What has been said here for the one treatment section applies accordingly to the other treatment sections. The treatment sections are preferably evenly distributed along the course of the sewer. Each of the treatment sections is a self-contained unit in that each of the treatment sections has all the elements required for treating the wastewater. The individual treatment sections are therefore independent of one another. They do not overlap and are spaced apart from one another.

[0015] In the treatment section, the wastewater is treated in various ways. The treatment section can therefore also be referred to as a treatment device. The treatment section can be located anywhere in the sewer where wastewater treatment is desired.

[0016] The treatment section can be understood as a location at which the wastewater is treated locally. The treatment section is preferably short compared to the length of the entire sewer. This is quantified herein by the fact that the treatment section preferably extends over a maximum of 20 m of a course of the sewer, particularly preferably over a maximum of 10 m. Preferably, the treatment section extends over 1 to 20 m of the course of the sewer, in particular over 3 to 10 m. The treatment section extends between the element passed first in the flow direction of the wastewater, which is defined herein as part of the treatment section, and the element passed last in the flow direction of the wastewater, which is defined herein as part of the treatment section.However, due to the heat exchanger system, the treatment section can extend significantly further along the sewer's course. The heat exchanger system can be more than 100 m long.

[0017] In the simplest case, the treatment section consists only of the first introduction point and the heat exchanger. In this case, the treatment section extends from the first introduction point to the heat exchanger, with the first introduction point and the heat exchanger each located within the treatment section.

[0018] First, gas bubbles containing oxygen and / or ozone are introduced into the wastewater at a first injection point. This conditions the wastewater, preventing or counteracting odor nuisance or corrosion of the sewer. The described process is particularly suitable for treating sewers carrying wastewater, where odor and corrosion can occur due to the formation of hydrogen sulfide (H2S). However, the described process can also be used to remove other unpleasant odorous substances from the wastewater or prevent their formation. Second, the wastewater is then passed through at least part of a heat exchanger and thermally treated. The term "thermal treatment" is used here as a generic term for "cooling" and "heating."

[0019] With the described process, two approaches can be pursued with regard to thermal treatment. In a first alternative, the wastewater is cooled using the heat exchanger device. In this case, the heat exchanger device can also be referred to as a cooling device or heat extraction element. Cooling the wastewater is useful with regard to wastewater treatment, in particular to counteract unpleasant odors or corrosion of the sewer. By removing heat, the oxygen uptake of the wastewater can be increased and bacterial activity in the wastewater and the sewer can be reduced. In the first alternative, the sole focus is therefore on treating the wastewater. In a second alternative, the wastewater is heated using the heat exchanger device. In this case, the heat exchanger device can also be referred to as a heating device.At first glance, heating wastewater might not seem sensible from a wastewater treatment perspective, particularly since warm wastewater is generally more likely to cause unpleasant odors and / or sewer corrosion than cold wastewater. However, it has surprisingly been shown that, by combining this with the introduction of gas bubbles of the size specified herein, unpleasant odors and sewer corrosion can be adequately counteracted despite the heating of the wastewater. The wastewater can therefore be used to absorb waste heat, for example, from an industrial plant, a household, or a data center. The gas bubbles allow a particularly large amount of waste heat to be transferred to the wastewater without causing unpleasant odors or corrosion of the sewer.It has been shown that introducing gas bubbles of the size specified here can be more energy-efficient than converting waste heat into cooling, for example, using a heat pump. In contrast to the first alternative, the second alternative focuses not only on wastewater treatment but also on removing waste heat from outside the sewer.

[0020] In general, the wastewater can be heated to a desired temperature using a heat exchanger. Since this may require heating instead of cooling, we generally refer to the terms "heat exchanger" and "thermal treatment" here. Depending on the requirements, the heat exchanger can be used to cool or heat the wastewater. The two alternatives described above can therefore be implemented with the same equipment and used accordingly.

[0021] The heat exchange device can be configured in various ways. In particular, any heat exchange device known from the prior art that is suitable for use in a sewer can be used. The heat exchange device is preferably arranged at a bottom of the sewer. The heat exchange device can, for example, be a stainless steel heat exchanger. The heat exchange device can be supplied with a heat exchange medium, for example, water, from outside the sewer.

[0022] In state-of-the-art solutions, the heat exchangers quickly become contaminated. The described method can prevent this by combining it with the introduction of gas bubbles at the initial point of introduction.

[0023] A possible source of contamination of the heat exchanger device is the formation of a biofilm on the surface of the heat exchanger. It has been found that the formation of such a biofilm can be prevented or at least slowed down by the gas bubbles and that an already existing biofilm can be removed again by the gas bubbles. The gas bubbles can react with an existing biofilm. When the gas bubbles break up, energy is released which can detach the biofilm from the surface of the heat exchanger. In particular, it was recognized according to the invention that the size of the gas bubbles plays a role in this effect. Accordingly, it is intended that at least 50% of the gas bubbles introduced into the wastewater at the first introduction point have a maximum diameter of 500 nm. Such gas bubbles can also be referred to as nanobubbles.The numerical values ​​provided quantify what is understood here as nanobubbles. The introduction of nanobubbles into wastewater has proven to be an effective way to counteract biofilm on the heat exchanger and thus maintain the efficiency of the heat exchanger in the sewer.

[0024] To ensure that the nanobubbles can effectively prevent the formation of biofilm on the heat exchanger, the heat exchanger is positioned a maximum of 5 m from the first introduction point. When viewed along the course of the wastewater channel, the distance between the first introduction point and the heat exchanger is therefore a maximum of 5 m. The smaller this distance, the better the nanobubbles can prevent the formation of biofilm on the heat exchanger. Therefore, the heat exchanger is preferably positioned a maximum of 2 m from the first introduction point, in particular a maximum of 0.5 m. Particularly when the heat exchanger is comparatively long, it is advantageous to introduce additional nanobubbles into the wastewater downstream of the first introduction point, for example, by linear dosing across the entire length of the heat exchanger.In general, however, it is sufficient that some of the nanobubbles are introduced into the wastewater before the wastewater passes through the heat exchange device.

[0025] Preferably, the first introduction point is upstream of the heat exchange device. This allows the nanobubbles to pass through the entire heat exchange device after the nanobubbles have been introduced into the wastewater. This is advantageous because it prevents contamination of the entire heat exchange device. It is therefore preferred that the wastewater, after the introduction of the gas bubbles at the first introduction point, be passed through the heat exchange device and thermally treated in the process. This refers to the entire heat exchange device. However, it is of course already advantageous if even just a part of the heat exchange device is protected from contamination. It is therefore not necessary for the first introduction point to be upstream of the entire heat exchange device.It is sufficient for the wastewater to be passed through at least a portion of the heat exchanger after the introduction of the gas bubbles at the first introduction point and to be thermally treated in the process. Preferably, the first introduction point is upstream of at least 30%, in particular at least 70%, of the heat exchanger.

[0026] Compared to larger gas bubbles, nanobubbles have the advantage of having little or no buoyancy. This allows the nanobubbles to remain in the wastewater for a comparatively long time. In particular, the nanobubbles can remain in the wastewater until the wastewater comes into contact with the heat exchanger. The nanobubbles can therefore be used to counteract contamination of the heat exchanger particularly effectively, as desired, because their small size allows them to remain in the wastewater for a sufficiently long time. Therefore, simply introducing the nanobubbles into the wastewater is sufficient. The process described is therefore particularly simple. By reducing or preventing the formation of biofilms, the efficiency of the heat exchanger remains at a high level. This means that the wastewater can be treated reliably for a comparatively long period of time.

[0027] The nanobubbles further condition the wastewater. This results from the introduction of oxygen and / or ozone into the wastewater. In the process described, the nanobubbles thus achieve two effects simultaneously.

[0028] Ideally, all gas bubbles introduced into the wastewater at the first introduction point have a maximum diameter of 500 nm. In this case, it can also be simplified to say that the gas bubbles introduced into the wastewater at the first introduction point are smaller than 500 nm. However, for the functioning of the method described here, it is not necessary for all gas bubbles introduced into the wastewater at the first introduction point to have a diameter of less than 500 nm. It has been found that usable results can also be achieved if half of the gas bubbles are larger. Therefore, it is generally provided here that at least 50% of the gas bubbles introduced into the wastewater at the first introduction point have a maximum diameter of 500 nm. However, it is preferred that at least 75% of the gas bubbles introduced into the wastewater at the first introduction point have a maximum diameter of 500 nm.It is further preferred that at least 50% of the gas bubbles introduced into the wastewater at the first introduction point have a maximum diameter of 300 nm, in particular that at least 75% of the gas bubbles introduced into the wastewater at the first introduction point have a maximum diameter of 300 nm.

[0029] Furthermore, it is preferred that at least 50% of the gas bubbles introduced into the wastewater at the first introduction point have a diameter in the range of 10 to 500 nm, in particular that at least 75% of the gas bubbles introduced into the wastewater at the first introduction point have a diameter in the range of 10 to 500 nm. Furthermore, it is preferred that at least 50% of the gas bubbles introduced into the wastewater at the first introduction point have a diameter in the range of 50 to 300 nm, in particular that at least 75% of the gas bubbles introduced into the wastewater at the first introduction point have a diameter in the range of 50 to 300 nm. Gas bubbles in a liquid are generally subject to a size distribution. The gas bubbles introduced into the wastewater at the first introduction point therefore have a diameter which is distributed.In contrast to the gas bubbles described below, this distribution is referred to herein as the first distribution. For the method described herein to function, it is sufficient that the first distribution is designed such that at least 50% of the gas bubbles have a maximum diameter of 500 nm. Preferably, the first distribution has a center of gravity in the range of 50 to 200 nm, for example, at 100 nm. The gas bubbles introduced into the wastewater at the first introduction point preferably have a main distribution around 50 to 200 nm.

[0030] Gas bubbles of the size described above can be generated in various ways. Nanobubble generators are commercially available. For example, the nanobubbles can be generated using generators that enrich a water stream with atmospheric oxygen or other gases such as pure oxygen or pure ozone. The water stream can be obtained from wastewater, particularly through filtration.

[0031] The gas bubbles introduced into the wastewater at the first point of introduction contain oxygen and / or ozone. Particularly preferably, the gas bubbles contain at least oxygen. However, ozone can be used additionally or even alternatively. The gas bubbles can be formed, for example, with air, oxygen-enriched air, ozone-enriched air, pure oxygen, or pure ozone.

[0032] In a preferred embodiment of the method, the gas bubbles are introduced into the wastewater at the first introduction point by introducing a first dosing agent into the wastewater at the first introduction point, wherein the first dosing agent is a liquid containing the gas bubbles or the first dosing agent is a gas containing oxygen and / or ozone.

[0033] In this embodiment, two possibilities are considered for introducing nanobubbles into wastewater. In the first possibility, a liquid is enriched with the nanobubbles and then introduced into the wastewater. The liquid can be enriched with the nanobubbles outside the sewer using a nanobubble generator and then introduced into the sewer. The liquid can be water, for example. In particular, fresh water or rainwater can be used as the liquid. However, wastewater from the sewer itself is generally more readily available. It has been found that the wastewater can be used as the liquid after filtering. The filtration filters out solids from the wastewater that could cause problems in the nanobubble generator.The wastewater is preferably filtered with a filter size of no more than 3 mm, for example, with a filter size of 1 mm. Fibers are preferably filtered out of the wastewater as much as possible. These could clog the nanobubble generator.

[0034] In the first option, the liquid containing the gas bubbles is referred to as the first dosing agent. The term "dosing agent" is used here generally for any substance added to the wastewater. This can be a chemical substance, but it can also simply be air or water with air bubbles.

[0035] For example, in the first possibility, the first dosing agent can be formed by water with air, water with oxygen-enriched air, water with ozone-enriched air, water with formic acid and air, water with formic acid and pure oxygen, water with formic acid and pure oxygen, ozone (which can also form performic acid if necessary), or hydrogen peroxide with formic acid and air.

[0036] In the second option, a gas containing oxygen and / or ozone is introduced directly into the wastewater. The gas bubbles are generated in the sewer directly at the first introduction point. This is possible, for example, using a sewer vane with appropriately dimensioned nozzles. In the second option, the first dosing agent is the gas containing oxygen and / or ozone. In the second option, the first dosing agent can be formed, for example, by air, oxygen-enriched air, ozone-enriched air, pure oxygen, or pure ozone. In general, it is preferred that the first dosing agent be introduced into the wastewater at a bottom of the sewer, evenly distributed throughout the wastewater.

[0037] In a further preferred embodiment of the method, the gas bubbles are introduced into the wastewater at the first introduction point by passing a first dosing agent through a perforated dosing hose laid at the first introduction point in the sewer, wherein the first dosing agent is a liquid containing the gas bubbles.

[0038] In particular, fresh water or rainwater can be used as the liquid. However, wastewater from the sewer itself is generally more readily available. It has been found that wastewater can be used as the liquid after filtering. However, to ensure the longevity of the gas bubble generator and pump technology used, filtered rainwater or fresh water is preferred. However, with large wastewater volumes, the demand for fresh water can be considerable. With the present embodiment, the demand for the liquid can be reduced. For this purpose, a perforated dosing hose is installed at the first introduction point in the sewer. The fact that the dosing hose is perforated means that it has pores. The pores can, for example, have a pore size of less than 0.1 mm.As the liquid containing the gas bubbles flows through the dosing hose, the gas bubbles can escape and enter the wastewater. The liquid can then be collected, reducing the need for liquid.

[0039] The dosing hose can extend over a dosing section along the course of the sewer. The dosing section is preferably between 0.5 and 5 m long, for example, 2 m. The wastewater flow can maintain sufficient tension on the dosing hose within the dosing section.

[0040] At the end of the dosing section, the dosing hose can be led out of the sewer. Alternatively, the dosing hose can be deflected 180° at the end of the dosing section and re-enter the dosing section. The return section of the dosing hose can be attached to the incoming section of the dosing hose to increase stability.

[0041] If the sewer is designed as a pressure pipeline, the dosing hose can be secured within the pressure pipeline using hose holders. The hose holders can be flow-optimized fastening elements with pulleys, for example, that hold the dosing hose at the bottom of the pressure pipeline. Generally, the pulleys position the dosing hose at the desired height within the pipeline. To install the dosing hose, the pressure pipeline can be drilled open so that the hose holders can be inserted into the pressure pipeline.

[0042] In a sewer designed as a gravity sewer, multiple dosing hoses can be installed along the sewer floor to achieve optimal distribution of the dosing agent across the entire cross-section of the sewer. In a gravity sewer, channel vanes, in particular, can facilitate the attachment and alignment of the dosing hose.

[0043] The first dosing agent in the dosing hose preferably has a pressure greater than the internal pressure of the sewer. This ensures that wastewater does not enter the dosing hose.

[0044] The dosing hose can be secured in the sewer with a weight element, either alternatively or additionally. The following two options are available.

[0045] In a first variant, a weight hose is arranged as the weight element outside the dosing hose, and the weight hose is connected to the dosing hose. In a second variant, a weight cable is arranged as the weight element inside the dosing hose. The weight cable can also serve as a tensioning cable. The dosing hose, particularly in variant 2, can be made of a microporous material and contain an integrated weight and tensioning cable in its outer skin. The weight and tensioning cable can be pulled inside the dosing hose. The weight and tensioning cable can be tensioned with couplings. This design ensures that the dosing hose remains reliably on the floor of the sewer and that the gas bubbles can reliably pass into the wastewater.

[0046] Particularly preferably, the dosing hose is spaced from a boundary of the sewer, in particular from a floor of the sewer. For example, the dosing hose can be held 1 to 5 mm above the sewer floor with an internal tension. This enables uniform dosing along the entire dosing hose.

[0047] The pores can be distributed over the entire circumference of the dosing hose. However, it is also preferable for the pores to be located only in a lower section of the dosing hose. This can increase the flow time of the gas bubbles in the wastewater and thus increase efficiency.

[0048] In a further preferred embodiment of the method, at least a portion of the liquid contained in the first dosing agent is passed through the dosing hose again as part of the first dosing agent after passing through the dosing hose.

[0049] In this embodiment, the first dosing agent is reused, which reduces the need for liquid.

[0050] In a further preferred embodiment of the method, the dosing hose has pores whose size depends on a pressure of the first dosing agent within the dosing hose.

[0051] By increasing the dosing pressure, the pore size can be adjusted in a pressure-controlled manner in order to regulate the amount of dosing agent introduced.

[0052] In a further preferred embodiment of the method, in the treatment section

[0053] ■ At a second introduction point arranged upstream of the heat exchanger device, gas bubbles containing oxygen and / or ozone are introduced into the wastewater, at least 50% of which have a diameter in the range of 1 to 100 μm. The second introduction point is preferably upstream of the first introduction point. However, it is also possible for the second introduction point to be arranged at the same position as the first introduction point when viewed in the direction of flow. It is sufficient that the gas bubbles introduced into the wastewater at the first introduction point can be distinguished from the gas bubbles introduced into the wastewater at the second introduction point at least to such an extent that the diameter distribution of the gas bubbles for the first introduction point and the second introduction point can be determined independently of one another.This is possible, for example, by introducing the gas bubbles into the wastewater at the first introduction point through a first introduction device, and introducing the gas bubbles into the wastewater at the second introduction point through a second introduction device that is different from the first introduction device. It is also conceivable for the second introduction point to be located downstream of the first introduction point.

[0054] As described above, nanobubbles can be used to condition wastewater and counteract fouling of the heat exchanger. In principle, both of these objectives can be achieved using nanobubbles alone. However, due to their small size, nanobubbles have the disadvantage that the amount of oxygen and / or ozone introduced into the wastewater via the nanobubbles is comparatively low. Furthermore, the production of nanobubbles is comparatively complex.

[0055] In the present embodiment, this is taken into account by introducing larger gas bubbles into the wastewater in addition to the nanobubbles. These gas bubbles can also be referred to as microbubbles. The microbubbles introduce more oxygen and / or ozone into the wastewater, so that fewer nanobubbles are sufficient. Microbubbles have greater buoyancy than nanobubbles and therefore remain in the wastewater for a shorter time. However, by combining them with the nanobubbles, the desired effect of counteracting contamination of the heat exchanger device can still be achieved. Basically, nanobubbles have the advantage over microbubbles in that they can remain in the wastewater for a long time because they have no buoyancy of their own. Nanobubbles can also react with existing H2S and thus render it harmless.Nanobubbles can also react with biological growth, particularly removing so-called "silica" growth on heat exchangers made of stainless steel, for example. Nanobubble generators are generally more expensive than microbubble generators, and the generation of nanobubbles is also more energy-intensive than the generation of microbubbles. A further advantage of introducing nanobubbles into wastewater is that the wastewater is conditioned in such a way that the overall oxygen uptake rate is significantly improved.

[0056] The advantage of microbubbles, however, is that they can enable a higher gross input of oxygen and / or ozone into the wastewater. Microbubble generators, such as microbubble-generating "jet pumps," are mass-produced in spa and pool technology and are therefore inexpensive to purchase. Microbubbles are slightly buoyant and are visible as white beads in the water. Nevertheless, microbubbles can remain in the wastewater for several minutes, thus ensuring a sufficiently high oxygen transfer into the wastewater even in gravity channels at low water levels.

[0057] In this embodiment, the advantages of nanobubbles and microbubbles are combined. On the one hand, the more complexly produced nanobubbles, with their advantageous properties, remain in the wastewater for a comparatively long time, while on the other hand, the enrichment of the wastewater with oxygen and / or ozone is additionally achieved via the microbubbles.

[0058] Ideally, all of the gas bubbles introduced into the wastewater at the second introduction point have a diameter in the range of 1 to 100 µm. In this case, it can also be simplified to say that the gas bubbles introduced into the wastewater at the second introduction point are between 1 and 100 µm in size. However, for the functioning of the method described here, it is not necessary for all of the gas bubbles introduced into the wastewater at the second introduction point to have a diameter in the range of 1 to 100 µm. It has been found that usable results can also be achieved if half of the gas bubbles are larger or smaller. Therefore, it is generally envisaged here that at least 50% of the gas bubbles introduced into the wastewater at the second introduction point have a diameter in the range of 1 to 100 µm.However, it is preferred that at least 75% of the gas bubbles introduced into the wastewater at the second introduction point have a diameter in the range of 1 to 100 μm. It is further preferred that at least 50% of the gas bubbles introduced into the wastewater at the second introduction point have a diameter in the range of 5 to 50 μm, in particular that at least 75% of the gas bubbles introduced into the wastewater at the second introduction point have a diameter in the range of 5 to 50 μm.

[0059] The gas bubbles introduced into the wastewater at the second introduction point have a diameter distributed according to a second distribution. For the method described herein to function, it is sufficient that the second distribution is designed such that at least 50% of the gas bubbles have a diameter in the range of 1 to 100 μm. Preferably, the second distribution has a center of gravity in the range of 5 to 50 μm, for example, at 10 μm. The gas bubbles introduced into the wastewater at the second introduction point preferably have a main distribution of around 5 to 50 μm.

[0060] Gas bubbles of the size described above can be generated in various ways. Microbubble generators are commercially available. In the area of ​​microbubble generation, introduction variants using air atomizers directly into the wastewater are particularly conceivable. In the area of ​​spa and pool technology, inexpensive microbubble-generating "jet pumps" are already available. These add microbubbles to a water stream by adding air. The operating principle is similar to nanobubble generators. However, microbubble generators are less expensive and, in terms of the gross gas input achieved, more energy-efficient.

[0061] In this embodiment, for example, water containing microbubbles can be introduced at the bottom of the sewer channel. At the same time, or slightly offset, water containing nanobubbles can be introduced at the bottom of the sewer channel. It is advantageous to add the microbubbles first to allow any remaining H2S to react with the more easily introduced microbubbles, thus protecting the nanobubbles, which require more energy to generate. Therefore, it is preferred that the second introduction point be arranged upstream of the first introduction point, spaced apart from the first introduction point.

[0062] The microbubbles can be introduced using a channel vane at the channel floor and / or via a pipe with holes at the channel floor. This solution is generally simpler and more cost-effective to install than linear dosing. The introduction at the channel floor is preferably carried out across the entire cross-section of the channel floor. Alternatively, introduction via linear dosing, for example, using a weighted hose with pores, is also useful.

[0063] The introduction of microbubbles can be repeated if the oxygen content of the wastewater decreases along the course of the sewer. This allows the nanobubbles to be retained for a particularly long time. If the nanobubbles are subsequently used up, nanobubbles can be reintroduced into the wastewater. The additional microbubbles and nanobubbles described in this section can, for example, be introduced into the wastewater in a subsequent treatment stage.

[0064] The gas bubbles introduced into the wastewater at the second introduction point contain oxygen and / or ozone. Most preferably, the gas bubbles contain at least oxygen. However, ozone can be used additionally or even alternatively. The gas bubbles can, for example, be formed with air, oxygen-enriched air, ozone-enriched air, pure oxygen, or pure ozone. For practical reasons, it is preferred, but not necessary, that gas bubbles made from the same gas are introduced into the wastewater at the first introduction point and at the second introduction point. When ozone is introduced into the wastewater, an ozone measurement of the sewer atmosphere should also be carried out at the treatment point in order to prevent an enrichment of the sewer atmosphere with ozone. This is useful for the protection of personnel who descend into the sewer system.This embodiment can also be implemented as a hybrid system for wastewater treatment to prevent odors and corrosion. This is particularly useful when using an existing dosing solution. Such dosing solutions are often optimized over years and often cannot be completely converted. For example, a substance such as calcium nitrate solution can be introduced into a sufficiently large reservoir of a device such as a microbubble-generating jet pump to enrich a water stream with microbubbles. By diluting the substance with water, a better and faster distribution of the substance in the wastewater stream can initially be achieved. In addition, oxygen introduced via microbubbles can react with any hydrogen sulfide already present in the wastewater and further enrich the wastewater with oxygen.This eliminates the need for the complex reoxidation of hydrogen sulfide (in the case of calcium nitrate solution) or precipitation of hydrogen sulfide (in the case of iron solution). In the hybrid system, hydrogen sulfide is also preferably stripped from the wastewater, for example, by means of compressed air introduced into the system and then extracted.

[0065] When controlling the dosing, for example, a pump signal from a dosing pump can be accessed to control the described dilution of a substance to be discharged into the wastewater and the enrichment of the combined dosing agent using microbubbles. This also makes it possible to react to dosing pauses, for example, during rainfall.

[0066] In order to further expand the described hybrid system, additional dosing devices for micro- and nanobubbles can be provided in the wastewater stream at other locations in the sewer.

[0067] In a preferred embodiment of the method, the gas bubbles are introduced into the wastewater at the second introduction point by introducing a second dosing agent into the wastewater at the second introduction point, wherein the second dosing agent is a liquid containing the gas bubbles or the second dosing agent is a gas containing oxygen and / or ozone. The statements made for the first dosing agent apply accordingly to the second dosing agent. In a further preferred embodiment of the method, in the treatment section,

[0068] ■ at a third introduction point located upstream of the first introduction point, gas bubbles containing oxygen and / or ozone are introduced into the wastewater, at least 50% of which have a diameter in the range of 0.1 to 10 mm.

[0069] If gas bubbles are introduced into the wastewater not only at the first introduction point but also at the second introduction point and at the third introduction point, it is preferred that the third introduction point is also arranged upstream of the second introduction point.

[0070] The gas bubbles introduced into the wastewater at the third point of introduction serve to precondition the wastewater. This is particularly useful when H2S is already present in the sewer. The gas bubbles introduced into the wastewater at the third point of introduction are comparatively large. Floating these gas bubbles is desirable. This strips out odorous substances present in the wastewater, such as H2S.

[0071] Ideally, all gas bubbles introduced into the wastewater at the third introduction point have a diameter in the range of 0.1 to 10 mm. In this case, it can also be simplified to say that the gas bubbles introduced into the wastewater at the third introduction point are between 0.1 and 10 mm in size. However, for the functioning of the method described here, it is not necessary for all gas bubbles introduced into the wastewater at the third introduction point to have a diameter in the range of 0.1 to 10 mm. It has been found that usable results can also be achieved if half of the gas bubbles are larger or smaller. Therefore, it is generally intended here that at least 50% of the gas bubbles introduced into the wastewater at the third introduction point have a diameter in the range of 0.1 to 10 mm.However, it is preferred that at least 75% of the gas bubbles introduced into the wastewater at the third introduction point have a diameter in the range of 0.1 to 10 mm. It is further preferred that at least 50% of the gas bubbles introduced into the wastewater at the third introduction point have a diameter in the range of 0.5 to 3 mm, in particular that at least 75% of the gas bubbles introduced into the wastewater at the second introduction point have a diameter in the range of 0.5 to 3 mm.

[0072] The gas bubbles introduced into the wastewater at the third introduction point have a diameter distributed according to a third distribution. For the method described herein to function, it is sufficient that the third distribution is designed such that at least 50% of the gas bubbles have a diameter in the range of 0.1 to 10 mm. Preferably, the third distribution has a center of gravity in the range of 0.5 to 3 mm, for example, at 1 mm. The gas bubbles introduced into the wastewater at the third introduction point preferably have a main distribution of around 0.5 to 3 mm.

[0073] Gas bubbles of the size described above can be generated in various ways, for example by bubbling compressed air from a hose. For example, the gas bubbles can be introduced into the wastewater at the third point of introduction by introducing compressed air into the wastewater via linear aeration. The desired bubble size can be achieved in the range of 0.1 to 10 mm. This type of bubble generation is known, for example, from pond aeration, for example as the "Drausy system." However, in the area of ​​oxygen input into the gravity sewer, experts assume that the residence time of the bubbles is not long enough to ensure economical operation due to the relatively high buoyancy. This is especially true at water levels below 30 cm, which frequently occur during normal operation and when odor problems arise.However, the combination with nanobubbles and optionally also microbubbles described here overcomes this problem.

[0074] The gas bubbles introduced into the wastewater at the third introduction point contain oxygen and / or ozone. More preferably, the gas bubbles contain at least oxygen. However, ozone can be used additionally or even alternatively. The gas bubbles can, for example, be formed with air, oxygen-enriched air, ozone-enriched air, pure oxygen, or pure ozone. For practical reasons, it is preferred, but not necessary, that gas bubbles made of the same gas are introduced into the wastewater at the first introduction point and at the third introduction point. In a preferred embodiment of the method, the gas bubbles are introduced into the wastewater at the third introduction point by introducing a third dosing agent into the wastewater at the third introduction point, wherein the third dosing agent is a liquid containing the gas bubbles or the third dosing agent is a gas containing oxygen and / or ozone.What was said for the first dosing agent applies accordingly to the third dosing agent.

[0075] In a further preferred embodiment of the method, in the treatment section

[0076] ■ the wastewater is irradiated with UV radiation.

[0077] In the present embodiment, the wastewater is irradiated. The treatment section can also be referred to as a "sewer sun."

[0078] UV radiation can have a disinfecting and / or oxygenating effect. UV radiation can create hydroxyl radicals in the wastewater, which can reduce the formation of H2S or react with H2S already formed. This can also help reduce or prevent biofilm on the surface of the heat exchanger.

[0079] The UV radiation is preferably UVC radiation.

[0080] Especially when the wastewater is irradiated with UV radiation, the heat exchanger system can be used to introduce excess waste heat, for example, from households, industrial plants, or data centers. The positive properties of the nanobubbles and, if necessary, the microbubbles, in combination with UV radiation, can prevent the negative effects of the introduced waste heat on the formation of H2S in the sewer. The efficient cooling of households, industrial plants, or data centers achieved in this way can be an overall energy-saving solution.

[0081] In a further preferred embodiment of the method, the UV radiation is generated with UV lamps attached to an exhaust hood and / or the UV radiation is generated with UV lamps attached to the heat exchanger device. The UV lamps are preferably LEDs. The UV lamps are preferably explosion-proof. The UV lamps are preferably arranged behind a UVC radiation-permeable cover, for example made of Plexiglas or high-strength glass. The surface of the cover is preferably cleaned regularly, in particular automatically. This can be done, for example, by blasting with water. To increase the cleaning performance, the water pressure can be increased, and nanobubbles can optionally be added to this water.

[0082] If at least some of the UV lamps are attached to the exhaust hood, the exhaust gas collected by the hood can be irradiated not only in the sewer but also in the sewer itself. This has the advantage that, for example, H2S stripped from the wastewater can be treated and largely rendered harmless during extraction.

[0083] If at least some of the UV lamps are attached to the heat exchanger, the waste heat from the UV lamps can be absorbed and dissipated by the heat exchanger. The dissipated heat energy can be used outside the sewer. In particular, the UV lamps on the heat exchanger are preferably waterproof and explosion-proof UVC LEDs.

[0084] In a further preferred embodiment of the method, in the treatment section

[0085] ■ an exhaust gas is discharged from the sewer through an exhaust opening formed downstream of the first introduction point in the treatment section.

[0086] Odorous substances can be removed from the sewer through the exhaust opening as exhaust gas. Exhaust gas can also be referred to as exhaust air. However, exhaust air generally has a composition that differs from that of air. Therefore, it is generally referred to as exhaust gas.

[0087] This embodiment is particularly preferred in combination with the embodiment in which oxygen- and / or ozone-containing gas bubbles are introduced into the wastewater at a third introduction point located upstream of the first introduction point, at least 50% of which have a diameter in the range of 0.1 to 10 mm. These comparatively large gas bubbles can strip odorous substances from the wastewater. These can exit the sewer through the exhaust opening directly in the treatment section.

[0088] An exhaust hood is preferably provided within the sewer. This is preferably connected to the exhaust opening in such a way that exhaust gas can be collected by the exhaust hood and directed to the exhaust opening. The exhaust hood is preferably mounted in such a way that the exhaust hood can be raised when the wastewater level in the sewer rises, so that the exhaust hood is not in the wastewater stream. The exhaust hood is preferably raised automatically when the wastewater level rises.

[0089] The exhaust gas is preferably extracted at the exhaust port. This allows sulfide and H2S to be removed from the sewer in a targeted manner.

[0090] The exhaust gas discharged from the exhaust port is preferably treated before being released into the environment, for example, with an activated carbon filter system. However, by using explosion-proof and waterproof UVC LEDs, the H2S contamination of the exhaust gas can be reduced in the sewer. This protects the downstream filters.

[0091] As a further aspect of the invention, a sewer with a treatment section for treating wastewater in the sewer is presented, wherein the sewer in the treatment section comprises:

[0092] ■ at a first introduction point, a first introduction device for introducing oxygen and / or ozone-containing gas bubbles, of which at least 50% have a maximum diameter of 500 nm, into the wastewater, and

[0093] ■ a heat exchange device which is arranged at least partially downstream of the first introduction point, wherein the heat exchange device is spaced a maximum of 5 m from the first introduction point.

[0094] The described advantages and features of the method are applicable and transferable to the described sewer, and vice versa. The described method is preferably carried out with the described sewer. The described sewer is preferably suitable for operation according to the described method.

[0095] The treatment section preferably extends over a maximum of 20 m of the sewer line.

[0096] In a preferred embodiment, the sewer has a source for a first dosing agent which is connected to the first introduction device for introducing the gas bubbles, wherein the first dosing agent is a liquid containing the gas bubbles and / or the first dosing agent is a gas containing oxygen and / or ozone.

[0097] In a further preferred embodiment, the sewer in the treatment section further comprises:

[0098] ■ at a second introduction point arranged upstream of the heat exchanger device, a second introduction device for introducing gas bubbles containing oxygen and / or ozone, of which at least 50% have a diameter in the range of 1 to 100 µm, into the wastewater.

[0099] In a further preferred embodiment, the sewer in the treatment section further comprises:

[0100] ■ at a third introduction point arranged upstream of the first introduction point, a third introduction device for introducing gas bubbles containing oxygen and / or ozone, of which at least 50% have a diameter in the range of 0.1 to 10 mm, into the wastewater.

[0101] In a further preferred embodiment, the sewer in the treatment section further comprises:

[0102] ■ several UV lamps to irradiate the wastewater with UV radiation.

[0103] In a further preferred embodiment of the wastewater channel, the UV lamps are attached to an exhaust hood, the UV lamps are attached to the heat exchanger, or some of the UV lamps are attached to an exhaust hood and some of the UV lamps are attached to the heat exchanger. In a further preferred embodiment, the wastewater channel further comprises in the treatment section:

[0104] ■ an exhaust gas opening formed downstream of the first introduction point in the treatment section for discharging an exhaust gas from the sewer.

[0105] The invention is explained in more detail below with reference to the figures. The figures show particularly preferred embodiments, to which the invention is not limited, however. The figures and the proportions depicted therein are merely schematic. They show:

[0106] Fig. 1: a sewer according to the invention,

[0107] Fig. 2: a dosing hose, which can alternatively be installed in the sewer from

[0108] Fig. 1 could be used.

[0109] Fig. 1 shows a sewer 1 with a treatment section 2 for treating wastewater 3 in the sewer 1. The fill level of the wastewater 3 in the sewer 1 shown is merely an example. Depending on the load, the sewer 1 can be filled significantly less or significantly more with wastewater 3.

[0110] Treatment section 2 extends over a maximum of 20 m of a section of wastewater 1. Treatment section 2 is defined by the fact that wastewater 1 has the elements described below in treatment section 2. Treatment section 2 extends from the element passed first in the flow direction 17 of wastewater 3 to the element passed last in the flow direction 17 of wastewater 3.

[0111] At a first introduction point 4, the wastewater channel 1 in the treatment section 2 has a first introduction device 14 for introducing oxygen and / or ozone-containing gas bubbles 7 into the wastewater 3, at least 50% of which have a maximum diameter of 500 nm. The gas bubbles 7 introduced into the wastewater 3 at the first introduction point 4 can also be referred to as nanobubbles. The gas bubbles 7 can be introduced into the wastewater 3 at the first introduction point 4 by introducing a first dosing agent into the wastewater 3 at the first introduction point 4, which is a liquid containing the gas bubbles 7 or a gas containing oxygen and / or ozone. The exit direction of the gas bubbles 7 is preferably directed downwards, towards the channel bottom, in order to retain the gas bubbles 7 in the wastewater 3 for as long as possible. Alternatively, the gas bubbles 7 can also be introduced directly via the bottom, e.g.through pipes embedded in the channel floor.

[0112] At a second introduction point 5, the wastewater channel 1 in the treatment section 2 has a second introduction device 15 for introducing oxygen and / or ozone-containing gas bubbles 7 into the wastewater 3, at least 50% of which have a diameter in the range of 1 to 100 μm. The gas bubbles 7 introduced into the wastewater 3 at the second introduction point 5 can also be referred to as microbubbles. The exit direction of the gas bubbles 7 is preferably downwards, towards the channel floor, in order to keep the gas bubbles 7 in the wastewater 3 for as long as possible. Alternatively, the gas bubbles 7 can also be distributed directly via the floor, e.g. through pipes embedded in the channel floor.

[0113] At a third introduction point 6, the wastewater channel 1 in the treatment section 2 has a third introduction device 16 for introducing oxygen- and / or ozone-containing gas bubbles 7 into the wastewater 3, at least 50% of which have a diameter in the range of 0.1 to 10 mm. The gas bubbles 7 introduced into the wastewater 3 at the third introduction point 6 can, for example, be finely bubbled compressed air.

[0114] Furthermore, the wastewater channel 1 has two heat exchange devices 8 in the treatment section 2, which are arranged downstream of the first introduction point 4. Alternatively, more heat exchange devices 8 could be provided.

[0115] The wastewater 3 is passed downstream of the discharge points 4, 5, 6 via the heat exchange devices 8 and is thermally treated, for example cooled.

[0116] Furthermore, the wastewater channel 1 in the treatment section 2 has several UV lamps 10, with which the wastewater 3 is irradiated with UV radiation 9. Some of the UV lamps 10 are attached to an exhaust hood 13, the remaining UV lamps 10 are attached to one of the heat exchange devices 8. An exhaust gas 11 can be collected via the exhaust hood 13 and discharged from the wastewater channel 1 through an exhaust opening 12 formed downstream of the first introduction point 4 in the treatment section 2.

[0117] Fig. 2 shows a modification of the sewer 1 from Fig. 1 in a plan view. Instead of the introduction device 14 shown in Fig. 1, the introduction device here has a dosing hose 18. The gas bubbles 7 can be introduced into the wastewater 3 at the first introduction point 4 via this, as is also the case in Fig. 1. For this purpose, a first dosing agent is passed through the dosing hose 18. The first dosing agent is a liquid containing the gas bubbles 7. The dosing hose 18 is perforated, i.e., has pores 19. This is indicated in that the dosing hose 18 is represented by a dotted line. The pores have a size that can depend in particular on a pressure of the first dosing agent within the dosing hose 18.

[0118] Outside the sewer 1, the dosing hose 18 is connected to a dosing agent source 20. This allows the first dosing agent to be introduced into the dosing hose 18. Since a return line of the dosing hose 18 is also connected to the dosing agent source 20, a portion of the liquid contained in the first dosing agent can be passed through the dosing hose 18 again as part of the first dosing agent after passing through the dosing hose 18.

[0119] List of reference symbols

[0120] 1 sewer

[0121] 2 treatment phase

[0122] 3 Wastewater

[0123] 4 first point of entry

[0124] 5 second point of entry

[0125] 6 third point of entry

[0126] 7 gas bubbles

[0127] 8 Heat exchanger device

[0128] 9 UV radiation

[0129] 10 UV lamps

[0130] 11 Exhaust

[0131] 12 Exhaust opening

[0132] 13 Exhaust hood

[0133] 14 first introduction facility

[0134] 15 second introduction device

[0135] 16 third introduction facility

[0136] 17 Flow direction

[0137] 18 Dosing hose

[0138] 19 pores

[0139] 20 Dosing agent source

Claims

Claims 1. A method for treating wastewater (3) in a treatment section (2) of a sewer (1), wherein in the treatment section (2) ■ at a first introduction point (4) oxygen and / or ozone-containing gas bubbles (7) are introduced into the waste water (3), of which at least 50% have a maximum diameter of 500 nm, and ■ the waste water (3) is then passed through at least part of a heat exchange device (8) and is thereby thermally treated, the heat exchange device (8) being spaced a maximum of 5 m from the first introduction point (4).

2. Method according to claim 1, wherein the gas bubbles (7) are introduced into the wastewater (3) at the first introduction point (4) by introducing a first dosing agent into the wastewater (3) at the first introduction point (4), and wherein the first dosing agent is a liquid containing the gas bubbles (7) or the first dosing agent is a gas containing oxygen and / or ozone.

3. Method according to claim 1, wherein the gas bubbles (7) are introduced into the wastewater (3) at the first introduction point (4) by passing a first dosing agent through a perforated dosing hose (18) laid in the sewer at the first introduction point (4), and wherein the first dosing agent is a liquid containing the gas bubbles (7).

4. The method according to claim 3, wherein at least a portion of the liquid contained in the first dosing agent is passed through the dosing hose (18) again as part of the first dosing agent after passing through the dosing hose (18).

5. The method according to claim 3 or 4, wherein the dosing tube (18) has pores (19) whose size depends on a pressure of the first dosing agent within the dosing tube (18).

6. Method according to one of the preceding claims, wherein in the treatment section (2) further ■ at a second introduction point (5) arranged upstream of the heat exchange device (8), gas bubbles (7) containing oxygen and / or ozone are introduced into the waste water (3), at least 50% of which have a diameter in the range from 1 to 100 µm.

7. Method according to one of the preceding claims, wherein in the treatment section (2) further ■ at a third introduction point (6) arranged upstream of the first introduction point (4), gas bubbles (7) containing oxygen and / or ozone are introduced into the waste water (3), at least 50% of which have a diameter in the range of 0.1 to 10 mm.

8. Method according to one of the preceding claims, wherein in the treatment section (2) further ■ the waste water (3) is irradiated with UV radiation (9).

9. The method according to claim 8, wherein the UV radiation (9) is generated with UV lamps (10) which are attached to an exhaust hood (13) and / or the UV radiation (9) is generated with UV lamps (10) which are attached to the heat exchange device (8).

10. Method according to one of the preceding claims, wherein in the treatment section (2) further ■ an exhaust gas (11) is discharged from the sewer (1) through an exhaust gas opening (12) formed downstream of the first introduction point (4) in the treatment section (2).

11. Sewer (1) with a treatment section (2) for treating wastewater (3) in the sewer (1), wherein the sewer (1) in the treatment section (2) comprises: ■ at a first introduction point (4) a first introduction device (14) for introducing oxygen and / or ozone-containing gas bubbles (7), of which at least 50% have a maximum diameter of 500 nm, into the wastewater (3), and ■ a heat exchange device (8) which is arranged at least partially downstream of the first introduction point (4), wherein the heat exchange device (8) is spaced a maximum of 5 m from the first introduction point (4).

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