Device and method for reconditioning fat-laden waste water

Abstract

Disclosed is an apparatus (2) for treating water, comprising: - an inlet (4) for supplying the water to be treated, - a sedimentation device (200) downstream of the inlet (4) for sedimentation of suspended solids out of the water to be treated, wherein the sedimentation device (200) comprises at least - an enrichment path (8) for enriching the water to be treated with a coagulant (10) and - a regulation path (18), downstream of the enrichment path (8), for introducing a regulation agent (22) that adjusts the pH of the water to be treated, and - a filter device (28), downstream of the sedimentation device (200), having a filter medium (30) and - a reverse osmosis device (40), downstream of the filter device (28), for further cleaning of the water, characterized in that the apparatus (2), at the inlet side, has a ventilation device (108) for introducing oxygen-containing gas into the water to be treated, the ventilation device being arranged upstream of the sedimentation device (200).

Description

[0001] Device and method for treating grease-laden wastewater

[0002] Description

[0003] The present invention relates to a device for treating grease-laden wastewater and a method for carrying out the same.

[0004] Multi-stage water treatment in the sedimentation plant can enable both the reduction and / or removal of hardness-forming compounds, particularly calcium ions, and lead to a reduction of TOC (total organic carbon) in drinking water. Although this two-stage approach is well known, it is not the standard approach in water treatment and is usually contradictory, since TOC reduction is achieved at a low pH, typically between 4.0 and 7.3, while the reduction of hardness-forming compounds can typically be achieved at higher pH values ​​between 9.5 and 11.5. The presence of TOCs also acts as an inhibitor of calcium precipitation.

[0005] Executing this special process typically requires extensive follow-up steps, making the system's dimensions virtually unsuitable for use with populations between 50 and 1,000. Such specifications are used, among other things, for the specification of small wastewater treatment plants according to DIN EN 12566 (Al version from 2003) and DWA-A 222.

[0006] The field of application of the plant according to the invention for water treatment and in particular water processing should in particular be in the range of up to 1000 EWs, preferably up to 200 EWs, particularly preferably up to 50 EWs.

[0007] A decisive advantage of using such a system is its small installation space requirement as well as its low number of maintenance cycles.

[0008] Based on this preliminary consideration, the object of the present invention is to provide a water treatment plant for a comparatively small water volume of less than 1000 PE, which is characterized by a compact design and virtually maintenance-free operation with the highest possible treatment efficiency. A tipping of the supplied water into the anaerobic state, e.g., due to extended rest periods, is to be prevented.

[0009] The present invention solves this problem by a device having the features of claim 1.

[0010] A water treatment device according to the invention comprises:

[0011] - an inlet for supplying the water to be treated,

[0012] - a sedimentation device connected to the inlet for the sedimentation of suspended matter from the water to be treated.

[0013] The sedimentation device does not have to be directly connected to the inlet; instead, additional purification devices, in particular a grease separator and / or a skimming device, can be arranged between the inlet and the sedimentation device. The sedimentation device has at least one enrichment path for enriching the water to be treated with a coagulant and a regulation path following the enrichment path for introducing a regulation agent that adjusts the pH of the water.

[0014] In addition, the device according to the invention has a filter device with a filter medium connected to the sedimentation device.

[0015] Finally, the device according to the invention has a reverse osmosis device connected to the filter device for further purification of the water.

[0016] On the inlet side, the device has an aeration device for introducing oxygen-containing gas into the water to be treated, which is arranged upstream of the sedimentation device.

[0017] The aeration device serves, on the one hand, to improve the mixing of the water and, on the other hand, to ensure that the water does not deteriorate into an anaerobic state, which would cause the composition of the water to change due to decomposition processes and the formation of further contaminants.

[0018] However, aeration in a device with the aforementioned partial processing areas is not without its problems, as the water tends to foam when chemicals are added, which hinders the settling of solids. It has therefore been found that it is advantageous to perform aeration prior to the addition of chemicals.

[0019] The aeration device can advantageously be part of a grease separator with a receiving chamber for the water to be treated, wherein the aeration device has a compressed gas nozzle for introducing the oxygen-containing gas into the water to be treated in the receiving chamber of the grease separator. The grease separator preferably operates according to the principle of gravity-induced phase separation. This allows the aeration device to be integrated into the device in a particularly space-saving manner.

[0020] Furthermore, the compressed gas nozzle of the aeration device can have an inlet opening for releasing gas pressure into the liquid. Furthermore, the device, in particular the grease separator, has a fill level gauge and / or a limit switch. The fill level gauge and / or the limit switch are particularly designed to monitor when a maximum fill level is reached. Thus, a maximum fill level for the receiving space of the grease separator is predetermined. The inlet opening of the aforementioned compressed gas nozzle is advantageously arranged below 70%, preferably below 50%, particularly preferably below 30% of the maximum fill level. This ensures that the gas has a sufficiently long passage path through the liquid and a correspondingly long time for contact and mixing.

[0021] In an advantageous, robust embodiment, the level measuring device has a mechanical level measurement, in particular a float.

[0022] The device may have one or more metering devices for supplying the coagulant and / or the regulating agent in the direction of flow. However, these one or more metering devices are arranged downstream of the aeration device. It has been shown that supplying chemicals before or during aeration promotes foam formation, which is advantageously avoided in this way.

[0023] The device can comprise a skimming device, in particular a belt skimmer, for skimming off a supernatant fat phase, which is arranged between the grease separator and the sedimentation device, preferably immediately downstream of the grease separator in the direction of flow. While the grease separator removes large quantities of fat from the water, the skimming device removes any remaining fats and / or oils, e.g., fat globules, etc. Upstream aeration enables improved buoyancy and increased agglomeration of colloidal oil droplets, which can then be removed by the downstream skimming device. Thus, the combination of aeration and skimming device results in optimal removal of fats and oils.

[0024] The ventilation device preferably comprises a system for generating compressed air. Although a gas cylinder can also be provided, the generation of compressed air is cost-effective for this application and enables a compact design of the device according to the invention. The system for generating compressed air is advantageously designed to be adjustable, particularly with regard to pressure adjustment.

[0025] The compressed air generation system can have one or more compressed air connections to other components of the device according to the invention. Advantageously, the device according to the invention comprises a cleaning device for introducing a cleaning medium for rinsing and / or CIP (clean in place) cleaning of the filter device and / or the reverse osmosis device. The aforementioned compressed air connections are part of this cleaning device, so that, for example, the cleaning medium can be pressurized with compressed air or residues of the cleaning medium can be blown out of the aforementioned devices.

[0026] The receiving space of the grease separator can advantageously have two chamber segments, which are spatially separated by a partition wall. The float can preferably be arranged in a first chamber segment. The compressed gas nozzle can advantageously be arranged in the second chamber segment. The chamber segments can have a connecting area for level compensation, which is preferably arranged at the bottom.

[0027] The receiving chamber of the grease separator can also have an overflow weir to separate any floating fat phase. This allows for quantitative fat separation through displacement. The oil and fat can then be collected in a collection tank together with the oil and / or fat phase separated by the skimming device.

[0028] The grease separator can advantageously be designed to collect treated water over a period of more than five days. Typically, anaerobic degradation already occurs during this time, which is advantageously prevented, in particular, by the aeration device.

[0029] Preferably, the aeration device is arranged directly downstream of a connection coupling of an inlet of the device for connection to a kitchen drain, in particular a siphon. Thus, the COD quantity is reduced immediately downstream of the inlet, preventing the system from tipping over into the anaerobic state.

[0030] A method according to the invention for treating water using the above-described device according to the invention is carried out in such a way that the water is aerated, preferably before introducing further chemicals, with the gas pressure of the introduced gas being at least 2 bar, preferably 3-5 bar. This prevents an anaerobic state and ensures improved mixing and improved grease and oil separation in this and subsequent purification stages.

[0031] The water to be treated can be collected over a period of more than five days. For kitchen wastewater, this means that collection can also take place over several days when the kitchen or restaurant is closed, during which no new water is supplied, and without the system processing insufficient quantities under suboptimal conditions or the water entering the anaerobic state and collapsing.

[0032] The above-described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become more clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0033] Fig. 1 is a schematic diagram of a method and system according to the invention.

[0034] The figure is purely schematic. Actual geometric proportions may differ from the figure.

[0035] Reference is made to Fig. 1, which shows a water treatment device 2. The water is, in particular, kitchen water with a high content of fat and other compounds generated in the kitchen.

[0036] The device 1 comprises an inlet 4 through which the water to be treated can be supplied in a flow direction 5, hereinafter also referred to as the flow direction. The inlet 4 can comprise a kitchen siphon.

[0037] The device then has a grease separator 100 after the inlet 4, which is arranged directly downstream of the inlet in the flow direction.

[0038] The maximum inflow rate of water to be treated, in particular kitchen wastewater, to be processed by the system according to the invention can be at least 100 l / h, preferably between 150-500 l / h. The grease separator 100 has a container 101 which defines a receiving space 113. The container 101 has at least one partition 102 which segments the container into at least two separation areas or chamber segments 104, 105. A line 103 between the inlet 4 and the grease separator 100 serves to feed the water to be treated into the first separation area 104. The second separation area 105 has an overflow 106. The partition 102 can in particular be designed as a baffle. The fill level of the first and / or second separation area 104, 105 is monitored by a fill level sensor 107, e.g., a float.

[0039] Furthermore, the grease separator has a ventilation device 108 for introducing an oxygen-containing gas, in particular compressed air, into the water to be treated in the container 101.

[0040] This ensures thorough mixing and prevents the water from tipping into an anaerobic state. The pressure should be at least 2 bar, preferably 3-5 bar. The aeration device 108 can comprise a compressed air generation system 109. A compressed gas nozzle 120, which is attached, for example, in a medium-tight manner to the wall of the container 101, has an inlet opening for introducing gas into the water to be purified and is arranged in the lower region of the liquid level of the container 101, thus providing a sufficiently large distance over which oxygen can be introduced into the liquid.

[0041] The water to be treated is then transferred, in particular pumped, to the pre-separator 110. The pre-separator 110 serves both as a sedimentation tank and for further fat separation by a skimming device 111 in the form of a so-called belt skimmer 111.

[0042] Belt skimmers or belt skimming devices are used in larger

[0043] Systems are familiar. Floating grease is skimmed off using a conveyor belt. However, practical application has shown that the fat content of the water being treated is still surprisingly high, despite the preceding grease separator, so that the use of the Belt Skimmer 111 significantly improves the water quality for subsequent process steps.

[0044] The skimmed oils and fats are collected in a collecting container 112 and, together with other fats generated in the kitchen, such as frying fat and cooking fat, are properly disposed of by an appropriate disposal company.

[0045] After this pretreatment, the water to be treated is optimally prepared for subsequent sedimentation. The water to be treated from the pre-separator 110 is fed via a line 130 into a sedimentation device 200, which includes a lamella clarifier 230, in which the sedimentation of contaminants takes place. In the transition between the pre-separator 110 and the lamella clarifier, a coagulum 10, preferably an iron(III) solution, particularly preferably an iron(III) chloride solution, is added. A corresponding dosing unit 140 for adjusting the flocculant content is arranged along the line 130. Part of the line 130 and the dosing unit 140 are part of an enrichment path 8 of the sedimentation device 200.

[0046] In addition, the pH is adjusted to a neutral or slightly alkaline value, preferably between 7.2 and 7.5. This can be achieved in particular by adding a regulating agent 22, preferably a basic agent, particularly preferably NaOH, in particular an NaOH solution. A dosing unit 150 for adjusting the pH is arranged along the line 130. The dosing unit 150 and / or the line 130 and / or a means arranged along the line can have a pH sensor 151, which is connected to the dosing unit 150 by means of a signal connection, as a wireless connection or as a signal cable. In particular, the dosing unit 150 can have a control and evaluation unit for processing the measurement signals of the pH sensor 151 and for adjusting the dosage amount of the basic agent to be added to the water to be treated.Another part of the line 130 and the dosing unit 150 are part of the control path 18 of the sedimentation device 200.

[0047] The flow path is designed to allow sufficient time for flocculation. A means 160 for reducing the flow velocity is arranged between the pre-separator 110 and the sedimentation device 200. The means can be arranged along the line 130 or in the line 130, or can be part of the line 130. This facilitates sedimentation and reduces the tendency toward turbulence. Particularly preferably, the means 160 for reducing the flow velocity is designed as a tubular reactor. The tubular reactor can have a temperature control device to provide constant binding conditions.

[0048] The sedimentation device 200 comprises a lamella clarifier 230, which has a conical sub-segment 201 on the bottom side for settling the sediment, at the tapered end of which is a sludge outlet 202. At a neutral to basic pH value, hydroxide flocs form in the sedimentation device 200, in particular iron hydroxide flocs, which capture approximately 90% of the undissolved substances and 50% of the dissolved substances. The sedimented sludge, with a dry matter content of preferably 3-5%, is periodically discharged into a sludge collection tank 250. The lamella clarifier preferably has a fill level measuring device 231 and / or a limit switch. Ideally, the fill level measuring device 231 and / or the limit switch or an arrangement of several limit switches detects both the total fill level and the fill level of the sludge orthe phase boundary, whereby emptying occurs not only based on the total fill level but also based on one of the two values. A capacitive sensor can be used for this purpose, which detects the phase boundary based on a change in capacitance. The sludge collection tank 250 has a sludge collection chamber 255 and a conical bottom 251 with a sludge drain 252 at the tapered end of the bottom 251. The sludge collection tank 250 also has a fill level sensor and / or a fill level limit switch 253. When a predetermined fill level is reached, the sludge can be drained from the sludge collection tank 250. By monitoring and / or determining the fill level, optimal post-sedimentation within the sludge collection tank 250 is achieved.

[0049] The sludge collection tank 250 has a permeable filter element 254, which preferably forms a wall region 256 of the sludge collection chamber 255, particularly preferably the conical bottom 251. The permeable filter element 254 is preferably a filter paper or filter cloth.

[0050] In the sludge collection tank 250, a liquid collection chamber 257 is arranged beyond the sludge collection chamber 255. The retentate from the filter element 254 is collected in this liquid collection chamber 257, while the permeate remains in the sludge collection chamber 250, further concentrating the sludge phase. This preferably occurs over a period of 12-24 hours.

[0051] The retentate 258 is then returned from the liquid collection chamber 257 to the pre-separator 110, while the concentrated sludge 259, preferably after reaching the predetermined fill level, can be drained from the sludge collection chamber 255 and the sludge collection tank 250 and fed to a drying system 260, for example, a biological dryer. A method for biological drying is generally known, and a corresponding exemplary method for the biological drying of sewage sludge is disclosed, among other things, in DE 41 11 314 C2. The aforementioned document describes only one variant within the scope of the present invention and can also be carried out in other ways. The dried sludge can then be processed into fertilizer, preferably together with collected food waste from the collection container 112.

[0052] The lamella clarifier 230 has a plurality of inclined lamellae 203, which are arranged at an angle of 2-45°, preferably 5-25°, relative to a vertical alignment of the lamellae. The sedimentation device designed as a lamella clarifier can also have a longitudinal axis 204, which is preferably arranged parallel to the vertical direction. The fluid flows through the lamella pack from bottom to top. A gaseous medium, in particular air, can be injected to support this process. Accordingly, the sedimentation device 200 has a gas inlet (not shown), which is preferably arranged below individual lamellae or a lamella pack.

[0053] The sedimentation device 200 also has an inlet opening 205, at which the line 130 opens into the sedimentation device 200. The inlet opening 205 is located above the sludge outlet 202. Furthermore, the sedimentation device 200 has an outlet opening 206 for a clarified liquid phase, which is located above the inlet opening 205. A transfer line 220 is attached to the outlet opening 206. An overflow weir (not shown) is preferably present within the sedimentation device 200 and is positioned in the region of the outlet opening 206.

[0054] The transfer line 220 then flows into a storage tank 310 of an ultrafiltration system 300. The ultrafiltration system 300 also includes a dynamic tangential flow filtration system (cross flow) 320 with one or more ceramic filtration discs 332, which are rotatably mounted in a housing 331. The average pore size of the ceramic discs can advantageously be between 10-50 nm. They define a so-called ceramic rotation membrane. The pre-treated wastewater is circulated between the dynamic tangential flow filtration system 320 and the storage tank 310. A filtrate of 50-500 l / h, preferably between 150-400 l / h, is directed towards a storage tank 410 of the reverse osmosis system 400. The ultrafiltration system has appropriate means, e.g.a pump, one or more lines, and a control unit that enables the rotary membrane to be flushed, preferably by generating backwash pulses. A sensor unit, particularly at a filtrate outlet, can be provided to control the periodicity of the backwash pulse generation. A sensor unit can be, for example, a pressure sensor and / or an optical sensor for determining the turbidity content in the filtrate and / or a flow sensor.

[0055] Due to the back pulses, colloids and / or bacteria on the surface of the rotating membrane are removed and can be rinsed out as retentate or recirculated into the feed container 310, thereby concentrating the supplied phase.

[0056] Short-chain fatty acids, which can cause a significant odor nuisance, such as butyric acid or similar, are not retained and are collected as part of the filtrate in the storage tank 410 of the reverse osmosis system 400.

[0057] The reverse osmosis system 400 is equipped with a membrane 402 and is operated at a yield rate of preferably more than 60 vol.%, preferably between 65-75 vol.%. Reverse osmosis is known per se. The system is designed for a maximum supply of more than 100 l / h, preferably for a maximum supply of a quantity between 120-300 l / h. It has an osmosis tank 410, for example with a wound membrane or another semi-permeable membrane 411, and an adjoining storage tank 420 for the permeate. The reverse osmosis system 400 has a drain line 430 for the permeate, which is arranged at a permeate drain 401 of the reverse osmosis system. The provided permeate meets all requirements for introduction into a conventional water network and can be used, for example, for flushing toilets. Therefore, the drain line 430 can advantageously have a connection 431 to a sanitary facility. The storage tank

[0058] 420 is part of the drain line 430. The storage tank 420 also has a level and / or limit level monitoring device

[0059] 421, which initiates an emergency emptying when a certain limit level is reached in the storage tank.

[0060] A disinfection dosing unit 440 for supplying a disinfectant to the permeate is also arranged along the drain line 430. The disinfection dosing unit 440 has a storage tank containing a disinfectant for water disinfection at a predetermined concentration. Typically, this can be chlorine or another disinfectant such as NaClO, particularly between 0.1 and 1 ppm.

[0061] Furthermore, an activated carbon filter 450 is provided in or on the osmosis tank 410 or along the drain line 430. This is preferably arranged upstream of the disinfection dosing unit 440 in the flow direction.

[0062] The osmosis tank 410 has a concentrate outlet 412 for draining a concentrate. The concentrate, which contains the impurities remaining after ultrafiltration, is returned to the grease separator 100 via the concentrate outlet 412. An elevated COD content of up to 3300 mg / l vs. 1000 mg / l can be detected in the concentrate. Due to the comparatively small amount of wastewater in the concentrate, the contaminant load is not significant.

[0063] Settling substances are completely removed by the previously described device 2, and semi-volatile lipophilic substances are largely removed. Over the course of a year, samples of the kitchen wastewater were taken and various parameters were determined through complete analyses:

[0064] 1. Kitchen water before introduction

[0065] Wastewater volume (m3 / d) = 1.9

[0066] Semi-volatile lipophilic substances, calculated as TR. (mg / l) <150 COD, calculated as O2 (mg / l) <1000

[0067] Settled solids, calculated as ABS (ml / l) < 10

[0068] Temperature (°C) <35

[0069] 2. Kitchen water at the filtrate outlet of the ultrafiltration

[0070] Wastewater volume (m3 / d) = 1.9 pH value 7.0 - 7.5

[0071] Semi-volatile lipophilic substances, calculated as TR (mg / l) <5 COD, calculated as O2 (mg / l) < 1000

[0072] Settled solids, calculated as ABS (ml / l) < 1.0

[0073] Temperature (°C) <35

[0074] 3. Kitchen water at the concentrate outlet of the reverse osmosis

[0075] Wastewater volume (m3 / d) = 0.57 pH value 7.0 - 7.5

[0076] Semi-volatile lipophilic substances, calculated as TR (mg / l) <20 COD, calculated as O2 (mg / l) <3333

[0077] Settled solids, calculated as ABS (ml / l) < 2.0

[0078] Temperature (°C) <35

[0079] 4. Kitchen water at the permeate outlet of the reverse osmosis

[0080] Wastewater volume (m3 / d) = 1.33 pH value 6.5 - 7.5

[0081] Semi-volatile lipophilic substances, calc. as TR (mg / l) <2.0

[0082] COD, calculated as O2 (mg / l) <200

[0083] Settled solids, calculated as ABS (ml / l) < 0.5

[0084] Temperature (°C) <35

[0085] The above-mentioned process and device process kitchen water from system catering (QSR) into process water suitable for flushing toilets or watering gardens.

[0086] In this process, all kitchen water is almost completely purified of semi-volatile lipophilic substances (SLS) and settleable solids (ABS). The pH of the wastewater is neutralized. The reverse osmosis concentrate, which reduces the wastewater flow by 70%, exhibits an increased COD concentration while maintaining the same contaminant load after ultrafiltration treatment when it returns to the grease separator. The dissolved and undissolved components of the wastewater are bound in the sludge, which can be processed in the dryer together with food waste into fertilizer for use in organic farming.

[0087] List of reference symbols

[0088] 2 Device

[0089] 4 Inlet

[0090] 5 Flow direction

[0091] 8 Enrichment pathway

[0092] 10 Coagulant

[0093] 18 Regulatory path

[0094] 22 Regulatory agent

[0095] 100 grease separators

[0096] 101 containers

[0097] 102 Partition wall

[0098] 103 lines

[0099] 104 Separation area

[0100] 105 Separation area

[0101] 106 Overflow

[0102] 107 Level sensor

[0103] 108 Ventilation device

[0104] 109 Device for generating compressed air

[0105] 110 pre-separators

[0106] 111 Skimming device

[0107] 112 collection containers

[0108] 113 Grease separator container accommodation space

[0109] 120 compressed gas nozzle

[0110] 130 line

[0111] 140 Dosing device

[0112] 150 dosing units

[0113] 151 Sensor

[0114] 160 means of reducing flow velocity

[0115] 200 sedimentation facility

[0116] 201 sub-segment

[0117] 202 sludge drain

[0118] 203 inclined slats

[0119] 204 Longitudinal axis 205 Inlet opening

[0120] 206 Drain opening

[0121] 210 document containers

[0122] 220 Transition

[0123] 230 lamella clarifiers

[0124] 231 Level measuring device

[0125] 250 sludge collection tank

[0126] 251 floor

[0127] 252 sludge drain

[0128] 253 Level sensor and / or level limit switch

[0129] 254 filter element

[0130] 255 Sludge collection room

[0131] 256 wall area

[0132] 257 Liquid collection chamber

[0133] 258 Retentate

[0134] 259 concentrated sludge discharged

[0135] 260 drying plant

[0136] 300 ultrafiltration plant

[0137] 310 storage tanks

[0138] 331 housing

[0139] 332 ceramic filtration discs

[0140] 400 reverse osmosis system

[0141] 401 Permeate effluent

[0142] 410 storage tank / osmosis tank

[0143] 412 Concentrate drain

[0144] 420 storage tank

[0145] 421 Level and / or limit monitoring device

[0146] 430 drain line

[0147] 431 connection (sanitary facility)

[0148] 440 Disinfectant dosing unit

[0149] 450 activated carbon filters

Claims

Patent claims 1. Device (2) for treating water, comprising: - an inlet (4) for supplying the water to be treated, - a sedimentation device (200) connected to the inlet (4) for the sedimentation of suspended matter from the water to be treated, wherein the sedimentation device (200) comprises at least - an enrichment path (8) for enriching the water to be treated with a coagulant (10) and - a regulation path (18) following the enrichment path for introducing a regulation agent (22) which adjusts the pH value of the water, and - a filter device (28) connected to the sedimentation device (200) with a filter medium (30) and - a reverse osmosis device (40) connected to the filter device (28) for further purification of the water, characterized in that the device (2) has on the inlet side an aeration device (108) for introducing oxygen-containing gas into the water to be treated, which aeration device is arranged upstream of the sedimentation device (200).

2. Device according to claim 1, characterized in that the aeration device (108) is part of a grease separator device (100) with a receiving space (113) for the water to be treated, wherein the aeration device (108) has a compressed gas nozzle (120) for introducing the oxygen-containing gas into the water to be treated in the receiving space (113) of the grease separator device (100).

3. Device according to claim 2, characterized in that the compressed gas nozzle (120) has an inlet opening, wherein the grease separating device (100) has a fill level measuring device and / or a limit switch (107), wherein the fill level measuring device and / or the limit switch (107) is designed to monitor the reaching of a maximum fill level, and wherein the inlet opening of the compressed gas nozzle (120) is below 70% of the maximum fill level is arranged.

4. Device according to one of the preceding claims, characterized in that the level measuring device (107) has a mechanical level measurement, in particular a float.

5. Device according to one of the preceding claims, characterized in that the device (2) has one or more dosing devices (140, 150) for supplying the coagulant (10) and / or the regulating agent (22) in the flow direction (5), wherein the one or more dosing devices (140, 150) are arranged downstream of the aeration device (108).

6. Device according to one of the preceding claims, characterized in that the device (2) has a skimming device (111), in particular a belt skimmer, for skimming off a supernatant fat phase, which is arranged between the fat separator (100) and the sedimentation device (200), preferably in the flow direction (5) immediately after the fat separator (100).

7. Device according to one of the preceding claims, characterized in that the ventilation device (108) has a system for generating compressed air (109).

8. Device according to one of the preceding claims, characterized in that the receiving space (113) of the grease separator (100) has two chamber segments (104, 105) which are spatially separated by a partition wall (102).

9. Device according to one of the preceding claims, characterized in that the receiving space (113) of the grease separator (100) has an overflow weir for separating a floating fat phase.

10. Device according to one of the preceding claims, characterized in that the grease separator (100) is designed to collect water to be treated over a period of more than 5 days.

11. Device according to one of the preceding claims, characterized in that the ventilation device (108) is arranged immediately after a connection coupling of an inlet (4) of the device (2) for connection to a kitchen drain, in particular a siphon.

12. A method for treating water with a device according to one of the preceding claims, characterized in that the gas pressure of the introduced gas is at least 2 bar, preferably 3-5 bar.

13. A method for treating water according to claim 12, characterized in that the water to be treated is collected over a period of more than five days.

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