Use of a reverse osmosis device in an apparatus for treating water

Abstract

The invention discloses a use of a reverse osmosis device (400) in an apparatus (2) for treating water, the apparatus (2) comprising the following elements: - 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 (400), downstream of the filter device (28), for further cleaning of the water.

Description

[0001] Use of a reverse osmosis device in a water treatment device

[0002] Description

[0003] The present invention relates to the use of a reverse osmosis device in a water treatment device.

[0004] Multi-stage water treatment in the sedimentation plant can enable both the reduction and / or removal of hardness-forming substances, 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 procedure for water treatment and is usually contradictory, as TOC reduction is typically achieved at a low pH value between 4.0 and 7.3, while the reduction of hardness-forming substances 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] Implementing this special procedure 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 space requirement as well as the low number of maintenance cycles.

[0008] Based on this preliminary consideration, the aim of the present invention is to provide a water treatment plant for a comparatively small water volume of less than 1000 EWs, which is characterized by a compact design and by almost maintenance-free operation with the highest possible cleaning efficiency.

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

[0010] The present invention involves the use of a reverse osmosis system in a compact, efficient system for treating heavily grease-laden kitchen wastewater with high COD content. The unique feature of this system lies in the interaction of a grease separator with the reverse osmosis system, which optimizes the overall efficiency and functionality of the system.

[0011] The system is designed as a compact system and is ideally suited for applications requiring less than 1000 l / h of processing, making it a perfect solution for smaller applications. Although reverse osmosis systems are known for their ability to achieve high levels of purity, they have a tendency to clog when processing highly contaminated wastewater. However, this problem is circumvented by the integrated system of the invention.

[0012] First, the water to be treated flows into the system through an inlet. This is where the cleaning process begins. Of particular importance is the grease separator, which is directly connected to the inlet. This serves to effectively separate fats and oils from the kitchen wastewater. The inclusion of a grease separator is a crucial innovation, as it significantly improves the efficiency of the entire system by pretreating the wastewater and reducing blockages often caused by grease and oil.

[0013] The grease separator is connected to a sedimentation system, which serves to precipitate suspended solids from the water. It's important to note that the sedimentation system is not necessarily directly connected to the inlet. Additional devices, such as an aeration device, can be located between the inlet and the sedimentation system.

[0014] The sedimentation system itself consists of two parts: an enrichment path that enriches the water to be treated with a coagulant, and a regulation path that is directly connected to the enrichment path and serves to introduce a pH-regulating agent.

[0015] In the next step of the process, the water passes through a filter system containing a special filter medium. The filter system prepares the water for the final purification stage, which is carried out by the reverse osmosis system.

[0016] The reverse osmosis system completes the system. Effective pretreatment with the grease separator and subsequent steps prevents the reverse osmosis system from becoming clogged. The reverse osmosis system reduces the COD content of the water to a level that allows it to be returned to the public water supply.

[0017] In summary, the present invention is a compact water treatment system specifically designed for the treatment of grease-laden kitchen wastewater with a high COD content, with a particular focus on the effective use of a grease separator. This is a central component and a decisive improvement over existing systems.

[0018] Advantageous embodiments of the invention are the subject of the subclaims.

[0019] The reverse osmosis system advantageously comprises a membrane plate module with a semipermeable membrane arranged along a plate plane. This membrane is less prone to clogging than, for example, a wound membrane.

[0020] The device may also comprise an activated carbon filter arranged along a permeate drain line.

[0021] To reduce the content of microorganisms in the water, the device can have a disinfection dosing unit for supplying disinfectant into the permeate, which is arranged along a drain line for permeate of the reverse osmosis device.

[0022] The reverse osmosis device advantageously has a return line for returning a concentrate from the reverse osmosis device to a grease separator upstream of the sedimentation system.

[0023] The reverse osmosis device can advantageously comprise means for cleaning in a CIP process.

[0024] The water to be treated may contain a fatty substance

[0025] Kitchen wastewater with an average COD value of more than 3,000 mg / l.

[0026] The sedimentation system may also include a return line for returning a filtrate from the sludge collection tank to a grease separator or grease separation device upstream of the sedimentation system. This grease separation device preferably operates according to the principle of gravity-induced phase separation. This reduces the volume of waste streams.

[0027] In addition, the lamella clarifier can be equipped with cleaning agents for a CIP process. This is also rather unusual in small systems and allows for further automation of the system's operation.

[0028] The small-scale plant makes it possible to process water with a very high fat content and an average COD value of more than 3,000 mg / l. This type of kitchen wastewater is generated, for example, in the catering industry.

[0029] 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. It shows:

[0030] Fig. 1 is a schematic diagram of a method and system according to the invention.

[0031] The figure is purely schematic. Actual geometric proportions may differ from the figure.

[0032] Reference is made to Fig. 1, which shows a device 2 for treating water. The water is, in particular, kitchen water with a high content of fat and other compounds commonly encountered in the kitchen. The device 1 comprises an inlet 4, via which the water to be treated can be fed to the device 2 in a flow direction 5, hereinafter also referred to as the flow direction. The inlet 4 can comprise a kitchen siphon.

[0033] The device then has a grease separator 100 after the inlet 4, which is arranged directly downstream of the inlet in the flow direction.

[0034] The maximum inflow quantity of water to be treated, in particular kitchen wastewater, through the system according to the invention can be at least 100 l / h, preferably between 150-500 l / h.

[0035] The grease separator 100 comprises a container 101 defining a receiving space 113. The container 101 has at least one partition wall 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 wall 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.

[0036] 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.

[0037] The aeration device 108 is preferably arranged directly downstream of a connection coupling of an inlet 2 of the device for connection to a kitchen drain, in particular a siphon. Thus, the amount of COD is reduced immediately downstream of the inlet, preventing tipping into the anaerobic state. This achieves 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 have a system for generating compressed air 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 gas into the water to be purified and is arranged in the lower region of the liquid level of the container 101, so that a sufficiently large distance is provided in which the oxygen can be introduced into the liquid.

[0038] 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.

[0039] Belt skimmers or belt skimming devices are common in larger plants. 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.

[0040] 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.

[0041] After this pretreatment, the water to be treated is optimally prepared for subsequent sedimentation. The water to be treated is fed from the pre-separator 110 via a line 130 into a sedimentation device 200, which comprises a lamella clarifier 230, where 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. The lamella clarifier preferably has a fill level measuring device 231 and / or a limit switch.Ideally, the level gauge 231 and / or the limit switch, or an arrangement of multiple limit switches, detects both the total fill level and the fill level of the sludge or phase boundary, with emptying occurring 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.

[0042] 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 alkaline 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 alkaline agent to the water to be treated.Another part of line 130 and the dosing unit 150 are part of the control path 18 of the sedimentation device 200. 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. This means can be arranged along line 130 or in line 130, or can be part of 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.

[0043] The sedimentation device 200 comprises a lamella clarifier 230, which has a conical sub-segment 201 at its bottom for settling the sediments, at the tapered end of which is a sludge outlet 202. At neutral to basic pH values, hydroxide flocs form in the sedimentation device 200, particularly 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.

[0044] The sludge collection tank 250 has a sludge collection chamber 255 and also has a conical bottom 251 with a sludge drain 252 at the tapered end of the bottom 251. Furthermore, the sludge collection tank 250 has a fill level sensor and / or a fill level limit switch 253. When a predetermined fill level is reached, the sludge collection tank 250 can be emptied. By monitoring and / or determining the fill level, optimal post-sedimentation within the sludge collection tank 250 is achieved.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The sedimentation device 200 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 lamellae stack 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 lamellae stack.

[0049] 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 arranged above the sludge outlet 202. Furthermore, the sedimentation device 200 has an outlet opening 206 for a clarified liquid phase, which is arranged above the inlet opening 205. A transfer line 220 is arranged at the outlet opening 206. An overflow weir (not shown) is preferably arranged within the sedimentation device 200 and is arranged in the region of the outlet opening 206.

[0050] 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 mounted rotatably 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 filtration system 320 and the storage tank 310. A filtrate of between 50-500 l / h, preferably between 150-400 l / h, is directed toward 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 flushes the rotating membrane, preferably by generating backwash pulses. A sensor unit, particularly at a filtrate outlet, can be provided to control the periodicity of the backwash pulses. 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.

[0051] 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 tank 310, thereby concentrating the supplied phase.

[0052] Short-chain fatty acids, which can cause significant odor nuisance, such as butyric acid, are not retained and are collected as part of the filtrate in the storage tank 410 of the reverse osmosis device 400.

[0053] The reverse osmosis device 400 is equipped with a semipermeable membrane 402 as part of a membrane plate module 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 yield of more than 100 l / h, preferably for a maximum yield of between 120-300 l / h. It comprises an osmosis tank 410, for example with a wound membrane or another semipermeable membrane 411, and an adjoining storage tank 420 for the permeate. The reverse osmosis device 400 has a drain line 430 for the permeate, which is arranged at a permeate drain 401 of the reverse osmosis device.

[0054] The permeate provided 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 420 is part of the drain line 430. Furthermore, the storage tank 420 has a fill level and / or limit level monitoring device 421, which initiates an emergency emptying when a certain limit level is reached in the storage tank.

[0055] 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 at a concentration between 0.1 and 1 ppm.

[0056] 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.

[0057] The osmosis tank 410 has a concentrate outlet 412, which serves to drain 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 compared to 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.

[0058] Settling substances are completely removed by the device 2 described above and low-volatility lipophilic substances are largely removed.

[0059] Over a period of one year, samples of kitchen wastewater were taken and various parameters were determined through full analyses:

[0060] 1. Kitchen water before discharge Wastewater volume (m3 / d) = 1.9

[0061] Semi-volatile lipophilic substances, calculated as TR (mg / l) <150 COD, calculated as O2 (mg / l) <1000 Settled solids, calculated as ABS (ml / l) <10 Temperature (°C) <35

[0062] 2. Kitchen water at the filtrate outlet of the ultrafiltration Wastewater quantity (m3 / d) = 1.9 pH value 7.0 - 7.5 Semi-volatile lipophilic substances, calculated as TR (mg / l) <5 COD, calculated as 02 (mg / l) <1000

[0063] Settled solids, calculated as ABS (ml / l) < 1.0

[0064] Temperature (°C) <35

[0065] 3. Kitchen water at the concentrate outlet of the reverse osmosis

[0066] Wastewater volume (m3 / d) = 0.57 pH value 7.0 - 7.5

[0067] Semi-volatile lipophilic substances, calculated as TR (mg / l) <20 COD, calculated as O2 (mg / l) <3333

[0068] Settled solids, calculated as ABS (ml / l) < 2.0

[0069] Temperature (°C) <35

[0070] 4. Kitchen water at the permeate outlet of the reverse osmosis

[0071] Wastewater volume (m3 / d) = 1.33 pH value 6.5 - 7.5

[0072] Semi-volatile lipophilic substances, calculated as TR (mg / l) <2.0 COD, calculated as O2 (mg / l) <200

[0073] Settled solids, calculated as ABS (ml / l) < 0.5

[0074] Temperature (°C) <35

[0075] The present process and the associated device process kitchen water from system catering (QSR) into process water suitable for flushing toilets or watering gardens.

[0076] 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 contaminants 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.

[0077] 2 Device

[0078] 4 Inlet

[0079] 5 Flow direction

[0080] 8 Enrichment pathway

[0081] 10 Coagulant

[0082] 18 Regulatory path

[0083] 22 Regulatory agent

[0084] 100 grease separators

[0085] 101 containers

[0086] 102 Partition wall

[0087] 103 lines

[0088] 104 Separation area

[0089] 105 Separation area

[0090] 106 Overflow

[0091] 107 Level sensor

[0092] 108 Ventilation device

[0093] 109 Device for generating compressed air

[0094] 110 pre-separators

[0095] 111 Skimming device

[0096] 112 collection containers

[0097] 113 Grease separator container accommodation space

[0098] 120 compressed gas nozzle

[0099] 130 line

[0100] 140 Dosing device

[0101] 150 dosing units

[0102] 151 Sensor

[0103] 160 means of reducing flow velocity

[0104] 200 sedimentation facility

[0105] 201 sub-segment

[0106] 202 sludge drain

[0107] 203 inclined slats

[0108] 204 Longitudinal axis 205 Inlet opening

[0109] 206 Drain opening

[0110] 210 document containers

[0111] 220 Transition

[0112] 230 lamella clarifiers

[0113] 231 Level measuring device

[0114] 250 sludge collection tank

[0115] 251 floor

[0116] 252 sludge drain

[0117] 253 Level sensor and / or level limit switch

[0118] 254 filter element

[0119] 255 Sludge collection room

[0120] 256 wall area

[0121] 257 Liquid collection chamber

[0122] 258 Retentate

[0123] 259 concentrated sludge discharged

[0124] 260 drying plant

[0125] 300 ultrafiltration plant

[0126] 310 storage tanks

[0127] 331 housing

[0128] 332 ceramic filtration discs

[0129] 400 reverse osmosis system

[0130] 401 Permeate effluent

[0131] 402 semipermeable membrane

[0132] 410 storage tank / osmosis tank

[0133] 412 Concentrate drain

[0134] 420 storage tank

[0135] 421 Level and / or limit monitoring device

[0136] 430 drain line

[0137] 431 connection (sanitary facility)

[0138] 440 Disinfectant dosing unit

[0139] 450 activated carbon filters

Claims

Patent claims 1. Use of a reverse osmosis device (400) in a device (2) for treating water, the device (2) comprising the following elements: - an inlet (4) for supplying the water to be treated, - a grease separator (100) connected to the inlet (4) for separating fats and oils from the water to be treated, - a sedimentation device (200) connected to the grease separator (100) for sedimenting 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 - the reverse osmosis device (400) connected to the filter device (28) for further purification of the water. Please note that the numbering of the grease separator (150) and the corresponding change in the connection sequence are hypothetical and must be adapted to your specific system.

2. Use according to claim 1, characterized in that the device (2) is designed to process a feed volume of less than 1000 l / h.

3. Use according to claim 1 or 2, characterized in that the reverse osmosis device (400) comprises a membrane plate module with a semipermeable membrane (402) arranged along a plate plane.

4. Use according to one of the preceding claims, characterized in that the device comprises an activated carbon filter (450) which is arranged along a drain line (430) for permeate.

5. Use according to one of the preceding claims, characterized in that the device (2) has a disinfection dosing unit (440) for supplying disinfectant into the permeate, which is arranged along a drain line (430) for permeate.

6. Use according to one of the preceding claims, characterized in that the reverse osmosis device (400) has a return line (258) for returning a concentrate from the reverse osmosis device (400) to the grease separator (100) upstream of the sedimentation device (200).

7. Use according to one of the preceding claims, characterized in that the reverse osmosis device (400) has means for cleaning in a CIP process.

8. Use according to one of the preceding claims, characterized in that the water to be treated is a fatty kitchen wastewater with an average COD value of more than 3,000 mg / l.

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