DE102017206990A1 - Process for wastewater treatment in a painting process and plant for painting components - Google Patents

Abstract

The invention relates to a process for wastewater treatment in a painting process, in which the components undergo the partial processes degreasing (10), phosphating (20) and cathodic dip-coating (30), wherein wastewater (50-57) is obtained in each of the sub-processes Steps: - cleaning the wastewater (50-57) in a biomembrane reactor plant (70), - further purifying the waste water (72) partially purified in the biomembrane reactor plant (70) in a reverse osmosis plant (80) to obtain a permeate (81) and a concentrate ( 82) and passing the permeate (81) through an ion exchanger (90) to obtain demineralized water (91) and recycling the demineralized water (91) to the painting process and using the recycled water (91) in at least one of the degreasing (10 ), Phosphating (20) and KTL coating (30). Furthermore, the invention relates to a system for painting components.

Description

The invention relates to a method for wastewater treatment in a painting process and a system for painting components. The invention relates in particular to a wastewater treatment for process wastewaters, which are produced in a plant for painting body components of a motor vehicle. If the term wastewater is used in this application, this is to refer exclusively to the process wastewater of the paint shop.

In a paint shop in the automotive industry, e.g. in automobile production, undergo the components to be painted, e.g. Vehicle bodies and bodywork components, a multi-stage process before applying the actual color coat. First, the components are cleaned in a degreasing process of fats and dust, then the component surface is provided in a phosphating process with a phosphate layer and then the components are coated in a KTL process with a cathodic dip coating (KTL). Wastewater is generated in all these sub-processes. In addition, one or more rinsing stages are provided in each of these sub-processes, in which the components are cleaned and in which further wastewater is obtained, which differs in its compositions. While the wastewater from the degreasing process primarily contains surfactants and oils, the wastewater from the phosphating process contains heavy metals. The wastewater from the KTL process in turn contains paint particles and electrolytes.

All these wastewater have to be treated and the losses have to be replaced by fresh water, partly demineralized water (DI water), which leads to high costs and is resource-intensive.

Various approaches are known to reduce water consumption in the painting process. So that beats DE 10 2012 218 495 A1 For example, a method of how the KTL process can be designed to save water. By using an ultrafiltration unit, water is separated from the electrocoating tank and partially used for the final rinse after the cathodic dip coating. Furthermore, the accumulating wastewater from the anolyte circuit can also be treated here by a suitable method.

Furthermore, from the unpublished patent application DE 102016215233.5 It is known to make the degreasing process more water-saving with a two-stage component flushing in the paint shop by treating the waste water of the first flushing stage and feeding it to the second flushing stage.

Despite these proposed measures, the water requirement in the painting process of a vehicle is enormous. In water-scarce areas, however, it is of particular importance that as little process water as possible is consumed. Because the drinking water supplies for the removal of fresh water are limited and a delivery of fresh water expensive.

It is therefore an object of the present invention to show a way as the amount of wastewater and the fresh water requirement of a paint shop in the automotive industry can be further reduced cost.

The object is achieved by a method for wastewater treatment according to claim 1 and by a system for painting components according to claim 5. Further advantageous embodiments will be apparent from the dependent claims and the description below.

• - Reinigen des Abwassers in einer Biomembranreaktoranlage,
• - weiteres Reinigen des in der Biomembranreaktoranlage teilgereinigten Abwassers in einer Umkehrosmoseanlage unter Erhalt eines Permeats und eines Konzentrats
• - Leiten des Permeats über eine Ionenaustauscheranlage unter Erhalt von vollentsalztem Wasser und Eluaten sowie
• - Zurückführung des vollentsalzten Wassers in den Lackierprozess und
• - Verwendung des rückgeführten Wassers in wenigstens einem der Teilprozesse Entfetten, Phosphatieren und KTL-Beschichten.

A process is described for wastewater treatment in a painting process in which the components undergo the partial processes of degreasing, phosphating and cathodic dip-coating, wastewater being produced in each of the sub-processes. The process for wastewater treatment comprises the steps:

• Purifying the waste water in a biomembrane reactor plant,
• - Further purification of the partially purified in the biomembrane reactor plant wastewater in a reverse osmosis system to obtain a permeate and a concentrate
• - Passing the permeate through an ion exchanger to obtain demineralized water and eluates and
• - Returning the demineralized water in the painting process and
• Use of the recycled water in at least one of the partial processes degreasing, phosphating and cathodic dip coating.

In one embodiment, the phosphating sub-process may contain, as further sub-processes, an activation process and / or a passivation process, as well as rinsing stages associated with these processes. In the activation process, crystallization nuclei are produced on the component surface, where the phosphate crystals grow in the subsequent actual phosphating process. The optional passivation process follows after the phosphating process, closing off any spots on the surface of the component that are still "open" or reactive after the phosphating process. The wastewater generated during the activation process and the passivation process becomes preferably also purified by the method according to the invention.

The living biological mass used in the biomembrane reactor plant metabolizes some of the substances dissolved in the wastewater (especially organic compounds), as a result of which the wastewater undergoes partial purification. The sewage sludge resulting from the biological process can e.g. be fed to a known sewage sludge treatment. The biomembrane reactor plant may comprise a single reactor or a plurality of interconnected reactors. Each biomembrane reactor has membranes with which the partially purified water can be separated while retaining the biological mass. The partially purified in the biomembrane reactor plant wastewater is then further purified in a reverse osmosis system.

In the reverse osmosis system, the partially purified wastewater is separated into a concentrate in which the pollutant concentration is increased compared to the partially purified wastewater, and a permeate, which is further freed from pollutants compared to the partially purified wastewater. The reverse osmosis system can be constructed in one or more stages. Likewise, several systems can be operated in parallel as redundant systems.

The permeate obtained in the reverse osmosis system is further processed in an ion exchange system to demineralized water. The ion exchanger system is not limited to a particular design, so the ion exchanger system can e.g. a cation exchanger and an anion exchanger.

The demineralized water is returned to the painting process where it is used in at least one of the partial degreasing, phosphating and cathodic dip coating operations, including the rinsing stages incorporated in the subprocesses. Use in the degreasing sub-process may be e.g. mean that the recirculated water is mixed with surfactants and used as a cleaning solution or that it is used as a rinsing liquid in a rinsing step following the degreasing zone. Likewise, the recycled water can be used in the actual phosphating or cathodic dip coating or as a rinsing liquid in a rinsing stage associated with phosphating or cathodic dip coating.

The inventive method, the water consumption for painting components can be reduced to a minimum. The method is inexpensive and feasible with little technical effort.

In order to stabilize the biology in the biomembrane reactor, in a preferred embodiment, the effluents from the various subprocesses are combined in a common reservoir and transferred as combined wastewater to the biomembrane reactor plant. The composition of the introduced into the biomembrane reactor wastewater is so homogenized, whereby the cleaning performance of the biological treatment stage can be increased. Before the introduction into the biomembrane reactor system, it may be possible to adjust the pH of the combined wastewater.

A further reduction of the accumulating wastewater quantity is achieved in one embodiment in that the wastewater concentrated in the reverse osmosis system (concentrate) is at least partially returned to the common storage tank. Depending on the composition of the concentrate, it may be completely returned to storage or it may be further processed beforehand, e.g. through an intermediate evaporator or similar.

The process according to the invention is particularly suitable and can be used to purify wastewater which is produced during the painting of body components or bodies of a motor vehicle.

Furthermore, a system for painting components is specified, in particular a system for painting body components of a motor vehicle, with a degreasing zone, a phosphating zone, a KTL coating zone, and several rinsing stages.

In the degreasing zone, the component is cleaned with a cleaning solution. This area may comprise one or more partial areas, for example a plurality of immersion baths or spraying devices, in or at which the component comes into contact with the cleaning solution. The cleaning solution is a conventional cleaning solution containing in particular at least one surfactant and is therefore suitable for removing dust and adhering dirt particles as well as for the attachment and detachment and at least partial removal of adhering oils and / or fats.

In the phosphating zone, the component is provided on its surface with a phosphate layer. This area may comprise one or more subregions, e.g. For example, the component can be brought into contact with a plurality of dipping baths or spraying devices with, for example, aqueous phosphate solutions.

In a preferred embodiment, the system for painting further comprises an activation zone and / or a passivation zone. In the activation zone, the component surface is activated before the phosphate layer is produced and, for example, nuclei are formed on which the phosphate growth takes place. In the passivation zone, the component surface is passivated after the formation of the phosphate layer, to which passively reactive "open" sites in the phosphating are passivated.

In the KTL coating zone, the component undergoes a cathodic dip coating, wherein a KTL layer is deposited on the component.

In the context of the invention, a rinsing stage is understood to mean a device in which the component is brought into contact with a rinsing solution. This can e.g. in the form of a dip bath or by a spray device or in a suitable other manner. The rinsing steps are used to clean the component. In the rinsing stages, e.g. with water, partially rinsed with demineralized water. In the system several rinsing stages are provided. Thus, for example, the degreasing zone is followed by at least one rinsing step, after the phosphating zone the component undergoes at least one further rinsing step and the cathodic-coated component is cleaned in at least one further rinsing step. The activation zone and passivation zone may also have one or more rinse stages.

In each of the zones degreasing zone, phosphating zone, KTL coating zone, activation zone and passivation zone and the rinsing stages, wastewater is produced.

In order to reduce the amount of wastewater arising, the plant for painting components further comprises a biomembrane reactor plant, a reverse osmosis plant and an ion exchanger, which are connected so that the wastewater is first purified in the biomembrane reactor to a partially purified wastewater, then continue the partially purified wastewater in the reverse osmosis system is purified to a permeate with separation of a concentrate and the permeate is further processed in the ion exchange system to demineralized water. The thus obtained demineralized water is traceable in at least one of the rinsing stages or zones and can be reused there. The feedback or the interconnection is e.g. realized by appropriate lines or conduit systems, which connect the individual components together.

An advantageous development of the plant for painting provides a memory in which the waste water from the degreasing zone, the phosphating zone, the KTL coating zone, if present from the activation zone and the passivation zone, and the rinsing steps is brought together and connected so that the merged wastewater from the storage in the biomembrane reactor plant can be introduced. By first combining the wastewaters from the various zones and rinsing stages, which may have very different compositions, the composition of the resulting combined wastewater is homogenized, which has an advantageous effect on the operation of the biomembrane reactor plant.

In a further advantageous embodiment, the reverse osmosis system is connected to the memory such that at least a portion of the concentrate from the reverse osmosis system is introduced into the memory.

The painting plant according to the invention is set up to carry out the process described above for wastewater treatment and, as such, achieves the same advantages and technical effects described for the process.

The inventive method for wastewater treatment and the plant for painting make it possible to treat the majority of the wastewater produced so that it can be recycled as demineralized water in the process. As a result, the system can be operated for painting virtually wastewater-free.

The system for painting a component can receive other components not explicitly mentioned here which are provided for carrying out the painting process and known to the person skilled in the art.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood with reference to the drawings and in conjunction with the following description of the embodiments. If the term "can" is used in this application, it is both the technical possibility and the actual technical implementation.

• 1 eine schematische Darstellung einer beispielhaften Anlage zur Lackierung von Karosseriebauteilen in der Kraftfahrzeugfertigung

Embodiments will be explained with reference to the accompanying drawings. It shows:

• 1 a schematic representation of an exemplary system for painting body parts in the automotive industry

In 1 is a schematic representation of a plant for painting body parts represented in the motor vehicle manufacturing, with only the interesting for the process according to the invention of wastewater treatment elements are shown. The remaining elements are omitted for clarity.

A component to be painted passes through the system 1 , wherein a plurality of sub-processes are performed sequentially on the component. The process for painting includes the partial processes degreasing 10 , Phosphating 20 , KTL coating 30 and painting 40 ,

For the degreasing subprocess 10 indicates the plant 1 for example, a degreasing zone 12 , as well as a first rinse stage 14 and a second rinse stage 16 on.

During further processing, the component undergoes the phosphating subprocess 20 in which the component is coated with a zinc phosphate layer. The sub-process phosphating 20 includes, by way of example, a phosphating zone 22 as well as two rinsing stages 24 and 26 , Optionally, in the sub-process phosphating 20 additionally an activation process with an activation zone 27 and a passivation process with a passivation zone 28 be provided. After the activation zone 27 and / or the passivation zone 28 can be provided not shown rinsing steps.

The component then becomes part of the KTL subprocess 30 in a cathodic dip coating zone 32 provided with a KTL coating and cleaned in one or more rinsing steps. Exemplary are two rinsing stages 34 and 36 shown.

In the subsequent sub-process painting 40 several paint layers, such as one or more color coat layers and a clear coat are applied to the component.

The degreasing in the subprocesses 10 , Phosphating 20 and KTL coating 30 accumulating wastewater 50 to 57 become a shared memory 60 fed and mixed in this, whereby the composition of the waste water is homogenized. Optionally, it may be provided that some or all of the wastewater strands 50 to 57 before the introduction into the store 60 pretreated in optional pre-treatment stages. So how can in 1 shown in the wastewater train 50 of the degreasing stage 10 an optional ultrafiltration system 58 the memory 60 be upstream and originating from the phosphating sub-process wastewater 52 first with a heavy metal precipitation 59 pretreated. Further or alternative pretreatment stages are conceivable.

The combined wastewater 61 Now according to the invention a biomembrane reactor plant 70 fed, where appropriate, a pH adjustment of the wastewater 61 can be made. The in the biomembrane reactor plant 70 contained living biological mass metabolizes a portion of the effluent pooled in the 61 contained substances, in particular organic compounds, causing the wastewater 61 at least partially cleaned. This falls sewage sludge 71 which can be further processed in a known sludge treatment.

Following the biomembrane reactor system 70 is the partially purified wastewater there 72 through a reverse osmosis system 80 headed and there in a permeate 81 and a concentrate 82 split, with the concentration of pollutants in the concentrate 81 higher than in wastewater 72 , The permeate 81 will now be via an ion exchanger 90 further purified to demineralized water 91 , The demineralized water 91 is returned to the painting process and in one or more of the sub-processes 10 . 20 . 30 reused. The return of demineralized water 91 can eg via one or more supply lines in single or all of the processing zones 12 . 22 and 32 and optionally 27 and 28 and / or in one or all of the rinsing stages, eg rinsing stages 14 . 16 . 24 . 26 . 34 . 36 respectively.

That in the reverse osmosis system 80 produced concentrate 82 can via a further supply line with upstream solids reduction 84 by a suitable method in the memory 60 be recycled, whereby the amount of non-reprocessable residual waste water is further reduced.

The plant and process management according to the invention make it possible that the majority of the wastewater is treated so that it can be recycled as demineralized water in the process. As a result, the system can be operated for painting virtually wastewater-free.

The embodiments are not to scale and are not restrictive. Modifications in the context of expert action are possible.

LIST OF REFERENCE NUMBERS

1

Plant for painting

10

Partial degreasing process

12

degreasing zone

14, 16

Rinse degreasing

20

Subprocess phosphating

22

phosphating

24, 26

Rinse phosphating

27

activation zone

28

passivation

30

Subprocess KTL coating

32

CED coating zone

34, 36

Rinsing stages KTL coating

40

paint

50 to 57

sewage

58

Ultrafiltration plant

59

Heavy metal precipitation

60

Storage

61

combined wastewater

70

Biomembranreaktoranlage

71

sewage sludge

72

partially purified wastewater

80

Reverse osmosis system

81

permeate

82

concentrate

84

Solids reduction

90

Ion exchange

91

completely desalinated water

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012218495 A1 [0004]
• DE 102016215233 [0005]

Claims (8)

Process for the purification of waste water in a painting process in which the components undergo the partial processes degreasing (10), phosphating (20) and cathodic dip-painting (30), whereby wastewater (50-57) is obtained in each of the sub-processes, comprising the steps of: Purifying the waste water (50-57) in a biomembrane reactor plant (70), - Further purification of the in the biomembrane reactor system (70) partially purified waste water (72) in a reverse osmosis system (80) to obtain a permeate (81) and a concentrate (82) and - Passing the permeate (81) via an ion exchanger system (90) to obtain demineralized water (91) and Recycling the demineralized water (91) into the painting process and using the recycled water (91) in at least one of the partial processes degreasing (10), phosphating (20) and cathodic dip coating (30). Method according to Claim 1 in which the phosphating sub-process (20) further comprises an activation process and / or a passivation process. Method according to one of Claims 1 or 2 in which the waste water (50-57) from the various sub-processes (10, 20, 30) are combined in a common store (60) and supplied to the biomembrane reactor plant as combined waste water (61). Method according to one of the preceding claims, wherein the concentrate (82) from the reverse osmosis system (80) at least partially in the common memory (60) is recycled. Plant for painting components comprising: a degreasing zone (12), a phosphating zone (22), a cathodic dip-coating zone (32), and a plurality of rinsing stages (14, 16, 24, 26, 34, 36), wherein in each of these zones ( 12, 22, 32) and rinsing stages (14, 16, 24, 26, 34, 36) wastewater (50-55) is obtained, characterized by a biomembrane reactor unit (70), a reverse osmosis unit (80) and an ion exchanger unit (90) connected so that - the wastewater (50 - 55) in the biomembrane reactor plant (70) is purified to a partially purified waste water (72), - the partially purified waste water (72) in the reverse osmosis plant (80) we further purified to a permeate (81 ) with separation of a concentrate (82) and - the permeate (81) in the ion exchanger system (90) is further purified to demineralized water (91) and - the deionized water (91) to at least one of the rinsing stages (14, 16, 24, 26, 34, 36) or zones (12, 22, 32) is traceable. Plant after Claim 5 furthermore with an activation zone (27) and / or a passivation zone (28), the waste water (56, 57) of which can likewise be introduced into the biomembrane reactor installation (70). Plant after Claim 5 or 6 , further comprising a reservoir (60) in which the waste water from the zones (12, 22, 27, 28, 32) and the rinsing stages (14, 16, 24, 26, 34, 36) is merged and thus connected in that the combined wastewater (61) can be introduced from the reservoir (60) into the biomembrane reactor plant (70). Plant after Claim 7 , characterized in that the reverse osmosis system (80) and the memory (60) are connected so that at least a portion of the concentrate (82) from the reverse osmosis system (80) in the memory (60) can be introduced.

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