EP3808896B1 - Method for producing paper containing waste paper and grass fibres - Google Patents
Method for producing paper containing waste paper and grass fibres Download PDFInfo
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- EP3808896B1 EP3808896B1 EP19203522.8A EP19203522A EP3808896B1 EP 3808896 B1 EP3808896 B1 EP 3808896B1 EP 19203522 A EP19203522 A EP 19203522A EP 3808896 B1 EP3808896 B1 EP 3808896B1
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- 244000025254 Cannabis sativa Species 0.000 title claims description 33
- 238000004519 manufacturing process Methods 0.000 title claims description 25
- 239000010893 paper waste Substances 0.000 title claims description 21
- 238000000034 method Methods 0.000 claims description 69
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 49
- 239000003795 chemical substances by application Substances 0.000 claims description 23
- 244000005700 microbiome Species 0.000 claims description 17
- 241000894006 Bacteria Species 0.000 claims description 13
- 239000003139 biocide Substances 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 13
- 239000006041 probiotic Substances 0.000 claims description 12
- 230000000529 probiotic effect Effects 0.000 claims description 12
- 235000018291 probiotics Nutrition 0.000 claims description 12
- 230000015572 biosynthetic process Effects 0.000 claims description 10
- 239000013505 freshwater Substances 0.000 claims description 10
- 229920002472 Starch Polymers 0.000 claims description 8
- 239000003292 glue Substances 0.000 claims description 8
- 239000008107 starch Substances 0.000 claims description 8
- 235000019698 starch Nutrition 0.000 claims description 8
- 229920003043 Cellulose fiber Polymers 0.000 claims description 4
- 239000011436 cob Substances 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 241000195493 Cryptophyta Species 0.000 claims description 2
- 240000007019 Oxalis corniculata Species 0.000 claims description 2
- 235000016499 Oxalis corniculata Nutrition 0.000 claims description 2
- 235000011116 calcium hydroxide Nutrition 0.000 claims description 2
- 239000000920 calcium hydroxide Substances 0.000 claims description 2
- 238000005259 measurement Methods 0.000 claims description 2
- 239000000523 sample Substances 0.000 claims description 2
- 240000007058 Halophila ovalis Species 0.000 claims 1
- 239000000123 paper Substances 0.000 description 52
- 239000000835 fiber Substances 0.000 description 32
- 235000015097 nutrients Nutrition 0.000 description 7
- 230000003115 biocidal effect Effects 0.000 description 4
- 239000000725 suspension Substances 0.000 description 4
- 239000002351 wastewater Substances 0.000 description 4
- 230000002378 acidificating effect Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000010924 continuous production Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000010865 sewage Substances 0.000 description 2
- 241001474374 Blennius Species 0.000 description 1
- 241000825107 Hierochloe Species 0.000 description 1
- 235000015466 Hierochloe odorata Nutrition 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 244000052616 bacterial pathogen Species 0.000 description 1
- 239000011111 cardboard Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000000855 fermentation Methods 0.000 description 1
- 230000004151 fermentation Effects 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000002503 metabolic effect Effects 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000007645 offset printing Methods 0.000 description 1
- 239000011087 paperboard Substances 0.000 description 1
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- 102000004169 proteins and genes Human genes 0.000 description 1
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- 238000004065 wastewater treatment Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Images
Classifications
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F9/00—Complete machines for making continuous webs of paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
- D21C5/005—Treatment of cellulose-containing material with microorganisms or enzymes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G9/00—Other accessories for paper-making machines
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G9/00—Other accessories for paper-making machines
- D21G9/0009—Paper-making control systems
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/14—Secondary fibres
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/005—Microorganisms or enzymes
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/20—Macromolecular organic compounds
- D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
- D21H17/24—Polysaccharides
- D21H17/28—Starch
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H19/00—Coated paper; Coating material
- D21H19/36—Coatings with pigments
- D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
- D21H19/54—Starch
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
- D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
- D21H21/16—Sizing or water-repelling agents
Definitions
- the invention relates to a method for producing paper containing waste paper fibers and grass fibers.
- it relates to a process for the production of paper which is obtained exclusively from waste paper fibers and grass fibers.
- the starting materials for the production of paper from waste paper and grass fibers if necessary with the addition of fresh fibers, shredded waste paper and grass particles, are first put into a pulper, into which process water is also introduced.
- a suspension of waste paper and grass particles is formed in the process water in the pulper, which is circulated and made pumpable by means of a whip, while the coarse cargo is crushed.
- the suspension is then extracted from the pulper, if necessary via a so-called refiner, in which the particulate fractions of the suspension are once more comminuted and defibrated, and also if necessary via sorting to separate out too coarse material, e.g.
- a paper web is formed on the screen support, which typically runs around in an endless belt, which is separated from the screen support and dried in further steps and, if necessary, further treated, e.g. by means of an application of glue or starch to set a Cobb 60 value, which is a measure of the liquid absorption of the paper and its size, for example with regard to the printability of the finished paper, plays an essential role.
- the paper web is further dried and wound onto a roll at the end of the manufacturing process.
- biocides are added to the process water in paper manufacture to prevent the formation and / or increase of process-damaging To prevent microorganisms in the process water or in the paper machine and thus to avoid the problems described above.
- biocide is viewed critically from an environmental point of view. They can be discharged from the paper machine with the wastewater and thus get into the environment.
- Biocides and their use in the production of paper containing grass fibers which is also known as "grass paper” and which also enjoys a special reputation from an ecological point of view, are especially to be assessed as sustainable and from an ecological point of view better than, for example, paper made from fresh fibers viewed critically, as these biocides in turn result in a poorer assessment of the life cycle assessment of the paper produced in this way.
- the toilet paper which can contain grass fibers, should help to quickly remove unpleasant smells after using the toilet and to kill pathogenic bacteria.
- probiotic bacteria are added to the toilet paper, which are introduced into the pulp during its production.
- the DE 20 2018 104 195 U1 describes a print carrier for use in offset printing.
- This print carrier is formed by paper or cardboard which contains a proportion of grass fibers in the fiber material composition.
- the aim of the invention is to provide a production method for paper containing waste paper fibers and grass fibers that can dispense with the use of biocides in the process water.
- a mass with waste paper fibers provided by the waste paper material introduced into the pulper and grass fibers provided by the grass material introduced into the pulper is deposited onto at least one carrier screen, e.g. in the form of a screen support, which can also be a continuous endless belt, with separation of at least part of the process water, applied to form a paper web.
- the further work steps known per se can be carried out, such as further processing of the fibers in a refiner, separation of excessively coarse material in sieves or sorting baskets or the like.
- a part of the process water separated when the mass is applied to the carrier screen is returned for renewed introduction into the pulper.
- this process water is originally obtained from fresh water, which fresh water has a pH value in the range from 7.0 to 8.5.
- biocides are not added to the process water, as is otherwise usual in the prior art, but rather probiotic bacteria.
- probiotic bacteria prevent or at least block the formation and / or the reproduction and / or the growth of process-damaging microorganisms, for example by depriving them of their nutrients or colonizing the available habitat and thus depriving the process-damaging microorganisms of settling.
- a product from the PIP Aquatec series from the Belgian supplier Chrisal NV which is an agent based on probiotic bacteria, can be used for the purposes described here.
- the pH of the process water is also monitored. Because without using a biocide and using probiotic bacteria in its place, there can still be a change, in particular a drop in the pH value, which, as mentioned above, affects the manufacturing process and possibly also the paper produced is disadvantageous. Thus, according to the method according to the invention, if the pH value has been found to fall below a threshold value, an increased dose of a basic agent is added in order to adjust the pH value of the process water to a target value and to keep the pH value at the target value .
- a pH value is set for the process water which, on the one hand, allows the probiotic bacteria to be active, but on the other hand does not drop into such a low value range that the problems described above are caused.
- the threshold value of the pH value is selected to be at least 0.2, in particular at least 0.3, greater than the target value. This is done because it has been shown that an early introduction of the basic agent and therefore timely countermeasures against over-acidification of the process water are necessary in order to be able to reliably set the pH value to the target value. Contrary to what was initially expected, it has been shown that counteracting by adding the basic agent does not allow this target value to be reached until the target value for the pH value is in the immediate vicinity. Then, despite the addition of the basic agent, the acid content of the process water surprisingly gets out of control, leading to an uncontrolled drop in the pH value well below the target value.
- the addition of a basic agent in increased dosage means that if a basic agent is added in a "basic amount" anyway to control the pH, the amount of the basic agent added is increased accordingly. If, however, no basic agent is added in the basic setting, the increased dosage can also indicate the beginning of the addition of the basic agent at all.
- probiotic bacteria may have to be replenished and added to the process water.
- Regular, in any case repeated or even continuous addition of the basic agent may also be necessary in order to be able to carry out continuous operation and continuous production of paper by the process according to the invention.
- the target value is selected at a pH of 6.5 to 7.0.
- it can be pH 6.7.
- the problems otherwise observed when the pH value is lowered, as described at the beginning, are avoided, and the probiotic bacteria are particularly effective against the process-damaging microorganisms.
- the threshold value from which the basic agent is added must be at least 0.2 above the target value for the pH. However, it should also advantageously not be too high above the target value, in order not to have premature addition of the basic agent.
- the threshold value can be at most 0.5 higher than the target value for the pH value of the process water.
- the invention advantageously proposes using milk of lime for this purpose.
- fresh water can be fed to the process water to replenish its volume.
- part of the process water is always drained from the paper machine and ends up in the wastewater.
- This "loss" of process water can be compensated for by adding fresh water accordingly.
- the supply of fresh water can also have an influence on the management of the pH value of the process water, since fresh water will typically have a higher pH value than the process water that is already in use.
- Fresh water that is added to the process water can typically have a pH of 7.0 to 8.5.
- the monitoring of the pH value of the process water can in particular take place continuously, in particular with a pH probe. This allows seamless, close-knit monitoring and thus timely and targeted intervention by adding the basic agent when the threshold value for the pH value is reached.
- the pH value can also be monitored by means of individual measurements made at predetermined intervals.
- a solution containing glue and / or starch dissolved in water can be applied to the paper web formed. This can take place, for example, in a so-called application of glue or starch.
- glue or starch also requires water for the formation of the solution, this water usually being separate from the process water of the other paper machine.
- the solution is typically applied at an elevated temperature, for example 135.degree.
- glue and starch in particular bring with them a considerable input of nutrients for harmful microorganisms and, in the area of the glue or starch application, correspondingly increased temperatures also favor the growth of microorganisms, there is also a considerable problem in the glue or starch application and the associated machine parts with the formation and growth of such microorganisms and the consequences outlined above.
- biocide is also used at this point in conventional paper machines and added to the solution or to the water used for this.
- probiotic bacteria but not biocides
- the pH value of the solution can be monitored will. If the pH value of the solution falls, in particular to a value below 4.5, a warning can advantageously be output so that measures can be taken to set a higher pH value.
- fresh fibers cellulose fibers that are not obtained from waste paper, but from fresh material are
- paper is produced using exclusively recovered paper fibers and grass fibers, and without using fresh cellulose fibers.
- the grass fibers used can in particular be fibers which are obtained by appropriate processing from dried, semi-dried or fresh sweet and / or sour grass and / or seaweed and / or algae.
- the figure which is a purely schematic representation, illustrates how the addition of the basic agent (the amount added per unit of time is shown as a curve over time in the lower representation with a dotted line) is carried out in an increased dose when the pH Value (the time course of which is shown in the upper illustration in a dashed line) is still above the target value drawn in as a continuous line in the upper illustration (also referred to as the target value in the figure).
- the pH value reaches the threshold value, which is a value of at least 0.2, preferably at least 0.3 above the target value (target value), and the addition of the basic agent with increased dosage is initiated.
- the target value for the pH value of the process water can be, for example, pH 6.5 to pH 7.
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- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Chemical & Material Sciences (AREA)
- Biochemistry (AREA)
- Paper (AREA)
Description
Die Erfindung betrifft ein Verfahren zum Herstellen von Altpapierfasern und Grasfasern enthaltendem Papier. Es betrifft insbesondere ein Verfahren zum Herstellen von Papier, das ausschließlich aus Altpapierfasern und Grasfasern gewonnen wird.The invention relates to a method for producing paper containing waste paper fibers and grass fibers. In particular, it relates to a process for the production of paper which is obtained exclusively from waste paper fibers and grass fibers.
Es ist bekannt, aus Altpapierfasern unter Beigabe auch von Grasfasern Papier herzustellen. So ist z.B. ein Verfahren zur Herstellung eines mehrlagigen, aus Altpapierfasern und Grasfasern gebildeten Papiers in der nachveröffentlichten
Der Vorteil von unter Verwendung von Grasfasern hergestelltem Papier ist in einer nachhaltigen Nutzung von Rohstoffen zu sehen. Denn Gras ist ein leicht verfügbarer, schnell nachwachsender Rohstoff, der lokal erzeugt und entsprechend in der Papierherstellung verwendet werden kann. Auch die Verwendung von Altpapierfasern in der Papierherstellung ist als Ressourcen schonend zu sehen. Denn so wird ein Kreislauf eröffnet, in dem einmal, oder sogar mehrmals bereits verwendetes Papiermaterial in den Wirtschaftskreislauf zurückgeführt und erneut für die Herstellung von Papier verwendet werden kann. Es kann so auf die Verwendung von Zellulosefrischfasern, die üblicherweise aus Holz von hierfür gefällten Bäumen gewonnenen werden, verzichtet, der Verbrauch an solchen Frischfasern kann jedenfalls deutlich reduziert werden. Dies hilft, die für die Luftreinhaltung und die CO2-Regulierung wichtigen Waldbestände zu schonen.The advantage of paper made using grass fibers can be seen in the sustainable use of raw materials. Because grass is an easily available, rapidly renewable raw material that is produced locally and can be used accordingly in papermaking. The use of recovered paper fibers in paper production should also be seen as conserving resources. Because in this way a cycle is opened in which paper material that has already been used once or even several times is returned to the economic cycle and again for the manufacture of paper can be used. It is thus possible to dispense with the use of fresh cellulose fibers, which are usually obtained from wood from trees felled for this purpose, and the consumption of such fresh fibers can in any case be significantly reduced. This helps to conserve the forests that are important for air pollution control and CO 2 regulation.
Bei der Papierherstellung werden Ausgangsmaterialien, für die Herstellung von Papier aus Altpapier- und Grasfasern, ggf. unter Zugabe auch eines Anteils von Frischfasern, zerkleinertes Altpapier und Graspartikel, zunächst in einen Pulper gegeben, in den auch Prozesswasser eingebracht wird. In dem Pulper wird so eine Suspension aus Altpapier und Graspartikeln in dem Prozesswasser gebildet, die mittels eines Aufschlägers unter Zerkleinern der groben Fracht umgewälzt und pumpfähig gemacht wird. Aus dem Pulper wird die Suspension dann, ggf. über einen sog. Refiner, in dem die partikulären Anteile der Suspension noch einmal zerkleinert und zerfasert werden, und ebenfalls ggf. über eine Sortierung zum Aussondern von zu grobem Material, z.B. über sog. Sortierkörbe, zu einer Aufbringeinheit verbracht, die die breiige Suspension auf eine Siebauflage aufbringt. Durch die Siebauflage, die auch als Trägersieb bezeichnet werden kann, strömt oder tropft Prozesswasser ab, das aufgefangen und in den Pulper rückgeführt wird. So bildet sich auf der Siebauflage, die typischerweise in einem Endlosband umläuft, eine Papierbahn aus, die von der Siebauflage getrennt und in weiteren Schritten getrocknet und ggf. weiter behandelt wird, z.B. mittels eines Leim- oder Stärkeauftrags zum Einstellen eines Cobb60-Werts, der ein Maß für die Flüssigkeitsaufnahme des Papiers ist und dessen Größe z.B. im Hinblick auf eine Bedruckbarkeit des fertigen Papiers eine wesentliche Rolle spielt. Die Papierbahn wird weiter getrocknet und am Ende des Herstellungsprozesses auf eine Rolle gewickelt.In paper production, the starting materials for the production of paper from waste paper and grass fibers, if necessary with the addition of fresh fibers, shredded waste paper and grass particles, are first put into a pulper, into which process water is also introduced. In this way, a suspension of waste paper and grass particles is formed in the process water in the pulper, which is circulated and made pumpable by means of a whip, while the coarse cargo is crushed. The suspension is then extracted from the pulper, if necessary via a so-called refiner, in which the particulate fractions of the suspension are once more comminuted and defibrated, and also if necessary via sorting to separate out too coarse material, e.g. via so-called sorting baskets, brought to an application unit, which applies the pulpy suspension to a sieve support. Process water flows or drips off through the screen support, which can also be referred to as a carrier screen, which is collected and returned to the pulper. A paper web is formed on the screen support, which typically runs around in an endless belt, which is separated from the screen support and dried in further steps and, if necessary, further treated, e.g. by means of an application of glue or starch to set a Cobb 60 value, which is a measure of the liquid absorption of the paper and its size, for example with regard to the printability of the finished paper, plays an essential role. The paper web is further dried and wound onto a roll at the end of the manufacturing process.
Bei der Herstellung von Papier herrscht im Bereich der Papiermaschine, zu der die vorstehend genannten technischen Einheiten zusammenfassend gerechnet werden, eine erhöhte Temperatur, insbesondere aufgrund der für das Trocknen der Papierbahn eingesetzten Wärme.In the manufacture of paper, there is an increased temperature in the area of the paper machine, to which the above-mentioned technical units are summarized, in particular due to the heat used for drying the paper web.
So herrschen im Bereich der Papiermaschine typischerweise Temperaturen von 25°C und mehr. Diese Temperaturen zusammen mit den in dem Prozesswasser durch die Zugabe von Altpapier, insbesondere aber auch von Gras, vorhandenen Nährstoffe, wie aus dem Grasmaterial gelösten Eiweißen, bilden ein ausgezeichnetes Milieu für das Wachstum von Mikroorganismen, wie etwa die Nährstoffe verstoffwechselnden Bakterien. Solche Bakterien oder andere Mikroorganismen sind im Bereich der Papiermaschine unerwünscht. Dies aus verschiedenen Gründen:
- Sie bilden Biofilme aus, die insbesondere in Bereichen der Papiermaschine, die schwer zugänglich sind, zu Problemen wie etwa Leitungsverstopfungen oder dergleichen führen können.
- Sie verursachen bei der Verstoffwechselung der Nährstoffe entstehende Faulgase, die zu einer überaus unangenehmen Geruchsentwicklung im Bereich der Papiermaschine führen können.
- Sie bedingen aufgrund der bei ihrer Umsetzung der Nährstoffe durch Verstoffwechslung entstehenden Stoffwechselprodukte eine Versauerung des Prozesswassers. Dies kann zu einer erheblichen Absenkung des pH-Werts führen, was nicht nur einen negativen Einfluss auf die Qualität des hergestellten Papiers hat, sondern auch zu nicht unerheblichen Problemen in der Behandlung des aus der Papiermaschine austretenden Abwassers führen kann. Ist dieses zu sauer, d.h. weist es einen zu geringen pH-Wert auf, so kann es z.B. von einer kommunalen Kläranlage zurückgewiesen werden. Untere Grenzwerte für pH-Werte des für die Einleitung in mit biologischer Klärung arbeitenden Kläranlagen vorgesehenen Abwassers liegen typischerweise bei pH 4, da ansonsten die Gefahr besteht, dass die für die Abwasseraufbereitung, insbesondere eine Verstoffwechslung der biologischen Fracht, eingesetzten Mikroorganismen absterben oder jedenfalls nicht mehr effektiv die biologische Fracht abbauen können.
- They form biofilms, which can lead to problems such as line blockages or the like, particularly in areas of the paper machine that are difficult to access.
- When the nutrients are metabolized, they cause fermentation gases which can lead to an extremely unpleasant odor in the area of the paper machine.
- Due to the metabolic products that arise when the nutrients are converted, they cause the process water to become acidic. This can lead to a considerable lowering of the pH value, which not only has a negative influence on the quality of the paper produced, but can also lead to not inconsiderable problems in the treatment of the wastewater emerging from the paper machine. If this is too acidic, ie if the pH value is too low, it can be rejected by a municipal sewage treatment plant, for example. Lower limit values for the pH values of the wastewater intended for discharge into sewage treatment plants working with biological treatment are typically pH 4, since otherwise there is a risk that the microorganisms used for wastewater treatment, in particular the metabolism of the biological load, will die off or at least no longer can effectively break down the biological load.
Entsprechend werden in der Papierherstellung dem Prozesswasser Biozide zugegeben, um die Entstehung und/oder Vermehrung von prozessschädigenden Mikroorganismen im Prozesswasser bzw. in der Papiermaschine zu unterbinden und so die vorstehend geschilderten Probleme zu vermeiden.Accordingly, biocides are added to the process water in paper manufacture to prevent the formation and / or increase of process-damaging To prevent microorganisms in the process water or in the paper machine and thus to avoid the problems described above.
Die Zugabe von Biozid wird allerdings unter Umweltgesichtspunkten kritisch gesehen. Sie können mit dem Abwasser aus der Papiermaschine ausgetragen werden und so in die Umwelt gelangen.The addition of biocide is viewed critically from an environmental point of view. They can be discharged from the paper machine with the wastewater and thus get into the environment.
Auch werden Biozide und deren Einsatz in der Herstellung von Grasfasern enthaltendem Papier, das auch als "Graspapier" bezeichnet wird und das auch einen besonderen Ruf unter ökologischen Gesichtspunkten genießt, eben als nachhaltig und unter ökologischen Gesichtspunkten besser zu bewerten als z.B. Papier aus Frischfasern, besonders kritisch gesehen, da durch diese Biozide die Ökobilanz des so hergestellten Papiers wiederum schlechter bewertet wird.Biocides and their use in the production of paper containing grass fibers, which is also known as "grass paper" and which also enjoys a special reputation from an ecological point of view, are especially to be assessed as sustainable and from an ecological point of view better than, for example, paper made from fresh fibers viewed critically, as these biocides in turn result in a poorer assessment of the life cycle assessment of the paper produced in this way.
In der
Die
Es wird im Rahmen der Erfindung angestrebt, ein Herstellungsverfahren für Altpapierfasern und Grasfasern enthaltendes Papier anzugeben, das auf den Einsatz von Bioziden im Prozesswasser verzichten kann.The aim of the invention is to provide a production method for paper containing waste paper fibers and grass fibers that can dispense with the use of biocides in the process water.
Zur Lösung dieser Aufgabe wird ein Verfahren mit den Merkmalen des Anspruchs 1 vorgeschlagen. Vorteilhafte Weiterbildungen eines solchen Verfahrens sind in den Ansprüchen 2 bis 10 angegeben.To solve this problem, a method with the features of claim 1 is proposed. Advantageous developments of such a method are given in claims 2 to 10.
Erfindungsgemäß werden bei einem Verfahren zum Herstellen von Altpapierfasern und Grasfasern enthaltendem Papier zunächst, in an sich üblicher Weise, in einen Pulper Altpapiermaterial und Grasmaterial sowie Prozesswasser eingebracht und dort in bekannter Weise durchmengt und zerkleinernd und Fasern aufbrechend behandelt. Weiter wird eine Masse mit durch das in den Pulper eingebrachte Altpapiermaterial bereitgestellten Altpapierfasern und durch das in den Pulper eingebrachte Grasmaterial bereitgestellten Grasfasern unter Abtrennung jedenfalls eines Teils des Prozesswassers auf wenigstens ein Trägersieb, z.B. in Form einer Siebauflage, die auch ein umlaufendes Endlosband sein kann, aufgebracht, um eine Papierbahn zu formen. Hierbei können zwischen dem Pulper und der Aufbringung der Masse auf das Trägersieb die an sich bekannten weitere Arbeitsschritte durchgeführt werden, wie ein weiteres Aufbereiten der Fasern in einem Refiner, ein Abtrennen von zu grobem Material in Sieben oder Sortierkörben oder dergleichen. Ebenfalls in an sich bekannter Weise wird jedenfalls ein Teils des beim Aufbringen der Masse auf das Trägersieb abgetrennten Prozesswassers für eine erneute Einbringung in den Pulper rückgeführt. Dieses Prozesswasser ist, wie dies ebenfalls üblich ist, ursprünglich aus Frischwasser erhalten, welches Frischwasser einen pH-Wert im Bereich von 7,0 bis 8,5 aufweist. Erfindungsgemäß werden dem Prozesswasser für jedenfalls eine Reduktion einer Bildung von prozessschädigenden Mikroorganismen nun nicht, wie im Stand der Technik ansonsten üblich, Biozide, sondern vielmehr probiotische Bakterien zugegeben. Diese probiotischen Bakterien verhindern oder blockieren zumindest die Bildung und/oder die Vermehrung und/oder das Wachstum von prozessschädigenden Mikroorganismen, indem sie ihnen z.B. die Nährstoffe nehmen oder den zur Verfügung stehenden Lebensraum besiedeln und damit den prozessschädigenden Mikroorganismen die Möglichkeit der Ansiedlung nehmen. Z.B. kann für die hier beschriebenen Zwecke ein Produkt der Serie PIP Aquatec des belgischen Anbieters Chrisal NV eingesetzt werden, bei dem es sich um ein Mittel auf Basis von probiotischen Bakterien handelt.According to the invention, in a method for producing waste paper fibers and paper containing grass fibers, initially, in a conventional manner, in a pulper of waste paper material and grass material as well as process water are introduced and mixed there in a known manner and treated in a known manner by crushing and breaking up fibers. Furthermore, a mass with waste paper fibers provided by the waste paper material introduced into the pulper and grass fibers provided by the grass material introduced into the pulper is deposited onto at least one carrier screen, e.g. in the form of a screen support, which can also be a continuous endless belt, with separation of at least part of the process water, applied to form a paper web. Here, between the pulper and the application of the mass to the carrier sieve, the further work steps known per se can be carried out, such as further processing of the fibers in a refiner, separation of excessively coarse material in sieves or sorting baskets or the like. Also in a manner known per se, a part of the process water separated when the mass is applied to the carrier screen is returned for renewed introduction into the pulper. As is also customary, this process water is originally obtained from fresh water, which fresh water has a pH value in the range from 7.0 to 8.5. According to the invention, in order to reduce the formation of process-damaging microorganisms, biocides are not added to the process water, as is otherwise usual in the prior art, but rather probiotic bacteria. These probiotic bacteria prevent or at least block the formation and / or the reproduction and / or the growth of process-damaging microorganisms, for example by depriving them of their nutrients or colonizing the available habitat and thus depriving the process-damaging microorganisms of settling. For example, a product from the PIP Aquatec series from the Belgian supplier Chrisal NV, which is an agent based on probiotic bacteria, can be used for the purposes described here.
Nach dem erfindungsgemäßen Verfahren wird weiterhin der pH-Wert des Prozesswassers überwacht. Denn ohne Einsatz von Biozid und unter Verwendung von probiotischen Bakterien an dessen Stelle kann es dennoch zu einer Veränderung, insbesondere einem Absinken des pH-Werts kommen, was, wie vorstehend erwähnt, für den Herstellungsprozess und ggf. auch für das hergestellte Papier nachteilig ist. So wird dann nach dem erfindungsgemäßen Verfahren bei einem festgestellten Absinken des pH-Werts unter einen Schwellwert ein basisches Mittel in erhöhter Dosierung zugegeben, um ein Einstellen des pH-Werts des Prozesswassers auf einen Zielwert zu erreichen und den pH-Wert auf dem Zielwert zu halten. So wird für das Prozesswasser ein pH-Wert eingestellt, der einerseits eine Aktivität der probiotischen Bakterien erlaubt, andererseits aber auch nicht in einen so niedrigen Wertebereich absinkt, dass die oben geschilderten Probleme hervorgerufen werden. Der Schwellwert des pH-Werts wird hierbei um wenigstens 0,2, insbesondere wenigstens 0,3 größer gewählt als der Zielwert. Dies wird deshalb so unternommen, da sich gezeigt hat, dass ein frühzeitiges Einleiten des basischen Mittels und mithin ein rechtzeitiges Gegensteuern gegen eine Übersäuerung des Prozesswassers notwendig ist, um den pH-Wert sicher auf den Zielwert einstellen zu können. Anders als zunächst erwartet, hat sich nämlich gezeigt, dass ein Gegensteuern durch Zugabe des basischen Mittels erst im unmittelbaren Umfeld des Zielwerts für den pH-Wert diesen Zielwert nicht erreichen lässt. Dann gerät trotz einer Zuführung des basischen Mittels der Säuregehalt des Prozesswassers nämlich überaschenderweise außer Kontrolle, kommt es zu einem unkontrollierten Absinken des pH-Werts deutlich unter den Zielwert.According to the method according to the invention, the pH of the process water is also monitored. Because without using a biocide and using probiotic bacteria in its place, there can still be a change, in particular a drop in the pH value, which, as mentioned above, affects the manufacturing process and possibly also the paper produced is disadvantageous. Thus, according to the method according to the invention, if the pH value has been found to fall below a threshold value, an increased dose of a basic agent is added in order to adjust the pH value of the process water to a target value and to keep the pH value at the target value . In this way, a pH value is set for the process water which, on the one hand, allows the probiotic bacteria to be active, but on the other hand does not drop into such a low value range that the problems described above are caused. The threshold value of the pH value is selected to be at least 0.2, in particular at least 0.3, greater than the target value. This is done because it has been shown that an early introduction of the basic agent and therefore timely countermeasures against over-acidification of the process water are necessary in order to be able to reliably set the pH value to the target value. Contrary to what was initially expected, it has been shown that counteracting by adding the basic agent does not allow this target value to be reached until the target value for the pH value is in the immediate vicinity. Then, despite the addition of the basic agent, the acid content of the process water surprisingly gets out of control, leading to an uncontrolled drop in the pH value well below the target value.
Die Zugabe eines basischen Mittels in erhöhter Dosierung meint hierbei, dass dann, wenn für die Steuerung des pH-Werts ohnedies ein basisches Mittel sozusagen in einer "Grundmenge" zugegeben wird, die Zugabemenge des basischen Mittels entsprechend erhöht wird. Wenn aber in der Grundeinstellung kein basisches Mittel zugegeben wird, so kann die erhöhte Dosierung auch den Beginn der Zugabe des basischen Mittels überhaupt bezeichnen.The addition of a basic agent in increased dosage means that if a basic agent is added in a "basic amount" anyway to control the pH, the amount of the basic agent added is increased accordingly. If, however, no basic agent is added in the basic setting, the increased dosage can also indicate the beginning of the addition of the basic agent at all.
Durch die erfindungsgemäße Maßnahme eines rechtzeitigen Einleitens des basischen Mittels kann dagegen eine Einstellung des Zielwerts erreicht werden, ohne dass der pH-Wert unter diesen Wert "schießt".By means of the measure according to the invention of introducing the basic agent in good time, on the other hand, an adjustment of the target value can be achieved without the pH value "shooting" below this value.
Die Kombination der mit der Erfindung angegebenen Mittel, also einmal der Einsatz von probiotischen Mikroorganismen und weiterhin die besondere vorstehend beschriebene Kontrolle des pH-Wertes des Prozesswassers, ermöglicht es nun, gerade auch bei der Herstellung von Graspapier, bei der durch den mit der Einbringung der Graspartikel verbundenen hohen Eintrag von biologischen Nährstoffen in das Prozesswasser die Bildung und das Wachstum von prozessschädigenden Mikroorganismen ein besonderes Problem darstellt, in der Herstellung des Papiers für das Prozesswasser auf den Einsatz von Bioziden zu verzichten, ohne eine Kontinuität der Herstellung zu verlieren. Es muss nämlich nicht bei einem zu starken Absinken des pH-Werts die Produktion auf der Papiermaschine etwa angehalten und das Prozesswasser verdünnt oder gar ausgetauscht werden. Stattdessen kann mit der vorstehend beschriebenen Kontrolle des pH-Werts kontinuierlich weiter produziert werden. Dabei müssen ggf. von Zeit zu Zeit (oder auch in einer kontinuierlichen Beimengung) probiotische Bakterien nachgeführt und dem Prozesswasser zugegeben werden. Auch eine regelmäßige, jedenfalls wiederholte oder gar kontinuierliche Zugabe des basischen Mittels kann erforderlich sein, um den kontinuierlichen Betrieb und die kontinuierliche Herstellung von Papier nach dem erfindungsgemäßen Verfahren vornehmen zu können.The combination of the means specified with the invention, i.e. once the use of probiotic microorganisms and furthermore the special control of the pH value of the process water described above, now makes it possible especially in the production of grass paper, where the formation and growth of process-damaging microorganisms poses a particular problem due to the high input of biological nutrients into the process water due to the introduction of the grass particles, in the production of paper for the process water on use to forego biocides without losing production continuity. If the pH value drops too much, production on the paper machine does not have to be stopped and the process water diluted or even replaced. Instead, production can continue continuously with the control of the pH value described above. From time to time (or in continuous admixture) probiotic bacteria may have to be replenished and added to the process water. Regular, in any case repeated or even continuous addition of the basic agent may also be necessary in order to be able to carry out continuous operation and continuous production of paper by the process according to the invention.
Es hat sich für die Durchführung des erfindungsgemäßen Verfahrens als vorteilhaft erwiesen, wenn der Zielwert bei einem pH-Wert von 6,5 bis 7,0 gewählt wird. Er kann z.B. bei pH 6,7 liegen. Bei einem solchen Zielwert werden die ansonsten bei einer Absenkung des pH-Wertes zu beobachtenden Probleme, wie sie eingangs geschildert sind, vermieden, und die probiotischen Bakterien wirken besonders gut gegen die prozessschädigenden Mikroorganismen.It has proven to be advantageous for carrying out the method according to the invention if the target value is selected at a pH of 6.5 to 7.0. For example, it can be pH 6.7. With such a target value, the problems otherwise observed when the pH value is lowered, as described at the beginning, are avoided, and the probiotic bacteria are particularly effective against the process-damaging microorganisms.
Der Schwellwert, ab dem das basische Mittel zugegeben wird, muss bei dem erfindungsgemäßen Verfahren um wenigsten 0,2 über dem Zielwert für den pH-Wert liegen. Er sollte aber mit Vorteil auch nicht zu hoch über dem Zielwert liegen, um nicht eine verfrühte Zugabe des basischen Mittels zu erhalten. Insbesondere kann der Schwellwert um höchstens 0,5 höher liegen als der Zielwert für den pH-Wert des Prozesswassers.In the method according to the invention, the threshold value from which the basic agent is added must be at least 0.2 above the target value for the pH. However, it should also advantageously not be too high above the target value, in order not to have premature addition of the basic agent. In particular, the threshold value can be at most 0.5 higher than the target value for the pH value of the process water.
Als zuzugebendes basisches Mittel kommt grundsätzlich jedes für die Papierherstellung unbedenkliche Mittel in Betracht. Mit Vorteil wird mit der Erfindung aber vorgeschlagen, hierfür Kalkmilch einzusetzen.As a basic agent to be added, basically any agent that is harmless for paper production can be considered. However, the invention advantageously proposes using milk of lime for this purpose.
Bei dem Verfahren nach der Erfindung kann dem Prozesswasser zur Auffüllung von dessen Volumen Frischwasser zugeführt werden. In der kontinuierlichen Herstellung von Graspapier wird ein Teil des Prozesswasser auch immer aus der Papiermaschine abgeleitet werden und in das Abwasser gelangen. Dieser "Verlust" an Prozesswasser kann durch entsprechende Zufuhr von Frischwasser ausgeglichen werden. Auch die Zufuhr von Frischwasser kann dabei einen Einfluss auf das Management des pH-Wertes des Prozesswassers haben, da Frischwasser typischerweise einen höheren pH-Wert haben wird als das bereits im Einsatz befindliche Prozesswasser. Frischwasser, das dem Prozesswasser beigemengt wird, kann typischerweise einen pH-Wert von 7,0 bis 8,5 haben.In the method according to the invention, fresh water can be fed to the process water to replenish its volume. In the continuous production of grass paper, part of the process water is always drained from the paper machine and ends up in the wastewater. This "loss" of process water can be compensated for by adding fresh water accordingly. The supply of fresh water can also have an influence on the management of the pH value of the process water, since fresh water will typically have a higher pH value than the process water that is already in use. Fresh water that is added to the process water can typically have a pH of 7.0 to 8.5.
Die Überwachung des pH-Werts des Prozesswassers kann insbesondere kontinuierlich, insbesondere mit einer pH-Sonde, erfolgen. Dies erlaubt eine lückenlose, engmaschige Überwachung und somit ein rechtzeitiges und gezieltes Eingreifen durch Zugabe des basischen Mittels bei Erreichen des Schwellwerts für den pH-Wert. Alternativ kann die Überwachung des pH-Werts aber auch mittels in zeitlich vorgegebenen Abständen vorgenommenen Einzelmessungen erfolgen.The monitoring of the pH value of the process water can in particular take place continuously, in particular with a pH probe. This allows seamless, close-knit monitoring and thus timely and targeted intervention by adding the basic agent when the threshold value for the pH value is reached. Alternatively, the pH value can also be monitored by means of individual measurements made at predetermined intervals.
Bei dem erfindungsgemäßen Verfahren kann zum Einstellen eines Cobb60-Werts des Papiers auf die ausgebildete Papierbahn eine in Wasser gelösten Leim und/oder Stärke enthaltende Lösung aufgebracht werden. Dies kann z.B. in einem sogenannten Leim- oder Stärkeauftrag erfolgen. Ein solcher Leim- oder Stärkeauftrag benötigt ebenfalls Wasser für die Bildung der Lösung, wobei dieses Wasser in der Regel getrennt von dem Prozesswasser der sonstigen Papiermaschine geführtes Wasser ist. Der Auftrag der Lösung erfolgt typischerweise mit erhöhter Temperatur, z.B. 135°C. Da gerade auch Leim und Stärke einen erheblichen Eintrag an Nährstoffen für schädliche Mikroorganismen mit sich bringen und im Bereich des Leim- oder Stärkeauftrags entsprechend ebenfalls erhöhte Temperaturen das Wachstum von Mikroorganismen begünstigen, besteht auch in dem Leim- oder Stärkeauftrag und den zugehörigen Maschinenteilen ein erhebliches Problem mit der Bildung und dem Wachstum solcher Mikroorganismen und den eingangs geschilderten Folgen. Entsprechend wird in üblichen Papiermaschinen auch an dieser Stelle Biozid eingesetzt und der Lösung bzw. dem für dieses eingesetzten Wasser zugegeben. Um auch hier ohne Biozid und mithin ökologisch vertretbar in der Graspapierherstellung arbeiten zu können, können mit Vorteil auch der Lösung für jedenfalls eine Reduktion einer Bildung von prozessschädigenden Mikroorganismen probiotische Bakterien, nicht jedoch Biozide, zugegeben werden und kann dabei der pH-Wert der Lösung überwacht werden. Sinkt dabei der pH-Wert der Lösung ab, insbesondere auf einen Wert von unterhalb 4,5, kann mit Vorteil eine Warnung ausgegeben werden, so dass Maßnahmen für das Einstellen eines höheren pH-Werts ergriffen werden können.In the method according to the invention, in order to set a Cobb 60 value for the paper, a solution containing glue and / or starch dissolved in water can be applied to the paper web formed. This can take place, for example, in a so-called application of glue or starch. Such an application of glue or starch also requires water for the formation of the solution, this water usually being separate from the process water of the other paper machine. The solution is typically applied at an elevated temperature, for example 135.degree. Since glue and starch in particular bring with them a considerable input of nutrients for harmful microorganisms and, in the area of the glue or starch application, correspondingly increased temperatures also favor the growth of microorganisms, there is also a considerable problem in the glue or starch application and the associated machine parts with the formation and growth of such microorganisms and the consequences outlined above. Correspondingly, biocide is also used at this point in conventional paper machines and added to the solution or to the water used for this. In order to be able to work in the grass paper production without biocide and therefore in an ecologically justifiable manner, probiotic bacteria, but not biocides, can also advantageously be added to the solution for at least a reduction in the formation of process-damaging microorganisms, and the pH value of the solution can be monitored will. If the pH value of the solution falls, in particular to a value below 4.5, a warning can advantageously be output so that measures can be taken to set a higher pH value.
Während bei dem erfindungsgemäßen Verfahren grundsätzlich auch Frischfasern (Zellstofffasern, die nicht aus Altpapier, sondern aus frischem Material gewonnen sind) eingesetzt werden können, wird in einer bevorzugten Variante des Verfahrens Papier unter Verwendung von ausschließlich Altpapierfasern und Grasfasern, und ohne Verwendung von Zellulose-Frischfasern, hergestellt.While in the method according to the invention in principle also fresh fibers (cellulose fibers that are not obtained from waste paper, but from fresh material are) can be used, in a preferred variant of the process, paper is produced using exclusively recovered paper fibers and grass fibers, and without using fresh cellulose fibers.
Als Grasfasern können bei dem erfindungsgemäßen Verfahren insbesondere Fasern eingesetzt werden, die durch eine entsprechende Aufbereitung aus getrocknetem, halbgetrocknetem oder frischem Süß- und/oder Sauergras und/oder Seegras und/oder Algen gewonnen werden.In the method according to the invention, the grass fibers used can in particular be fibers which are obtained by appropriate processing from dried, semi-dried or fresh sweet and / or sour grass and / or seaweed and / or algae.
Nachstehend wird die hier beschriebene und beanspruchte Erfindung noch einmal näher erläutert anhand der beigefügten Figur. Dabei zeigt:
- Fig. 1
- eine schematische Darstellung des zeitlichen Verlaufs gemessenen pH-Wertes des Prozesswassers (obere Kurve) und der Zugabemenge eines basischen Mittels (untere Kurve) aufgetragen über in der Darstellung synchronisierte Zeitachsen.
- Fig. 1
- a schematic representation of the pH value of the process water measured over time (upper curve) and the amount of a basic agent added (lower curve) plotted over time axes that are synchronized in the representation.
In der Figur, die eine rein schematische Darstellung ist, wird veranschaulicht, wie die Zugabe des basischen Mittels (die Zugabemenge pro Zeiteinheit ist als Verlauf über die Zeit in der unteren Darstellung mit einer gepunkteten Linie dargestellt) in erhöhter Dosis vorgenommen wird, wenn der pH-Wert (dessen zeitlicher Verlauf in der oberen Darstellung in einer gestrichelten Linie gezeigt ist) noch oberhalb des in der oberen Darstellung als durchgehende Linie eingezeichneten Zielwertes (in der Figur auch als Sollwert bezeichnet) liegt. Links in der oberen Kurve gelangt der pH-Wert an den Schwellwert, der um einen Wert von wenigstens 0,2, vorzugsweise wenigstens 0,3 oberhalb des Zielwerts (Sollwerts) liegt, und die Zugabe des basischen Mittels mit erhöhter Dosierung wird eingeleitet.The figure, which is a purely schematic representation, illustrates how the addition of the basic agent (the amount added per unit of time is shown as a curve over time in the lower representation with a dotted line) is carried out in an increased dose when the pH Value (the time course of which is shown in the upper illustration in a dashed line) is still above the target value drawn in as a continuous line in the upper illustration (also referred to as the target value in the figure). On the left in the upper curve, the pH value reaches the threshold value, which is a value of at least 0.2, preferably at least 0.3 above the target value (target value), and the addition of the basic agent with increased dosage is initiated.
So wird erreicht, dass der pH-Wert zwar zunächst weiter abfällt, allerdings nicht in den Bereich niedriger pH-Werte (in den sauren Bereich) überschießt, sondern sehr gut eingefangen wird und dann um den Zielwert schwankt bei einer vergleichsweise konstanten Zugabemenge, bzw. Dosierung des basischen Mittels.This ensures that the pH value initially drops further, but does not overshoot into the range of lower pH values (into the acidic range), but is captured very well and then fluctuates around the target value with a comparatively constant addition or Dosage of the basic agent.
Der Zielwert für den pH-Wert des Prozesswassers kann z.B. bei pH 6.5 bis pH 7 liegen.The target value for the pH value of the process water can be, for example, pH 6.5 to pH 7.
Claims (10)
- A method for the production of waste paper fibres and paper containing grass fibres obtained by processing from dried, semi-dried or fresh and/or sour grass and/or sea grass and/or algae, wherein waste paper material and grass material as well as process water are introduced into a pulper and a mass comprising waste paper fibres provided by the waste paper material introduced into the pulper and grass fibres provided by the grass material introduced into the pulper is applied to at least one carrier wire with separation of at least a part of the process water in order to form a paper web, wherein at least a part of the process water is recycled for renewed introduction into the pulper, wherein the process water is originally obtained from fresh water having a pH in the range of 7.0 to 8.5, wherein probiotic bacteria, but not biocides, are added to the process water for at least a reduction of a formation of process-damaging microorganisms, are added to the process water for at least a reduction of a formation of process-damaging microorganisms, and wherein the pH value of the process water is monitored and, if a drop in the pH value below a threshold value is detected, a basic agent is added in increased dosage in order to achieve an adjustment of the pH value of the process water to a target value of 6.5 to 7.0 and to maintain the pH value at this target value, wherein the threshold value of the pH value is at least 0.2, in particular at least 0.3, greater than the target value.
- The method according to claim 1, characterised in that the threshold value of the pH is greater than the target value by at most 0.5.
- The method according to one of the preceding claims, characterised in that milk of lime is added as basic agent.
- The method according to one of the preceding claims, characterised in that fresh water is added to the process water to replenish its volume.
- The method according to claim 4, characterised in that the fresh water supplied has a pH value of 7.0 to 8.5.
- The method according to one of the preceding claims, characterised in that the pH value of the process water is monitored continuously, in particular with a pH probe.
- The method according to one of the claims 1 to 5, characterised in that the monitoring of the pH value is carried out by means of individual measurements taken at predetermined time intervals.
- The method according to any one of the preceding claims, characterised in that a solution containing glue and/or starch dissolved in water is applied to the formed paper web to adjust a Cobb60 value of the paper, wherein probiotic bacteria, but not biocides, are added to the solution for at least a reduction of a formation of process-damaging microorganisms, and that the pH value of the solution is monitored.
- The method according to claim 8, characterised in that a warning is issued if the pH value of the solution drops below 4.5.
- The method according to one of the preceding claims, characterised in that the paper is produced using only waste paper fibres and grass fibres, in particular without using fresh cellulose fibres.
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US5965128A (en) * | 1997-08-13 | 1999-10-12 | University Of Georgia Research Foundation Inc. | Control of enterohemorrhagic E. coli 0157:H7 in cattle by probiotic bacteria and specific strains of E. coli |
WO2009070955A1 (en) * | 2007-12-05 | 2009-06-11 | Shandong Fuyin Paper & Environmental Protection Technology Co., Ltd | Grass type unbleached paper products and production method thereof |
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