JP2012233271A - Slime control method in pulp and paper production processes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide indices of slime control situations which can be measured rapidly and by a simple method in production processes of pulp and paper in which a slime control agent is added, and a slime control method using the indices.SOLUTION: There is provided a slime control method in pulp and paper production processes, in which a slime control agent is added in production processes of pulp and paper and an addition amount of the slime control agent is controlled 19, 20 based on concentrations 21, 22 of ATP (adenosine-triphosphate) in process water 13, 17.

Description

  The present invention relates to a slime control method in a paper pulp manufacturing process. More specifically, in the pulp and paper manufacturing process to which the slime control agent is added, the slime in the pulp and paper manufacturing process that controls the addition amount of the slime control agent based on the concentration of ATP (adenosine triphosphate) in the process water. It relates to a control method.

  The pulp slurry, white water, and white water filtered water in the paper pulp manufacturing process contain a large amount of water and many organic additives such as starch-derived organic substances derived from the pulp and water temperature of 30-50. It has become a very favorable environment for microbial growth. Some microorganisms secrete sticky products, which are mixed with pulp slurries and solids in white water to form slime. Slime is a seed box for the pulp and paper manufacturing process, machine chest, stock inlet, wire pit, white water silo, KP receiving chest, DIP receiving chest, waste paper storage tank, white water transfer pipe, poly disc filter and pressurized flotation device In addition, it has occurred and adhered to the raw material recovery system such as attached tanks, felt, rolls, etc., and it has interfered with the operation. Product quality deteriorates due to occurrence of “paper-defects”, and further, productivity decreases due to “paper break”. In order to prevent such slime damage, a slime control agent is usually added, and for example, sodium hypochlorite and a halogenated hydantoin compound are used as the slime control agent (patent) Reference 1). In addition, a method for preventing bacteria that cause slime from adhering to the wall of the apparatus has been proposed (see Patent Document 2).

  A conventional method for adding a slime control agent in a paper pulp manufacturing process is to intermittently add a predetermined amount at regular intervals using a timer and an injection device. In the case of such intermittent addition, when the pulp and paper manufacturing process is operated under a certain condition, it is an efficient and economical method. However, the microorganism is rapidly changed due to a sudden change in the process condition or for some reason. In the case of proliferation, the situation cannot be dealt with, and as described above, the operation of the pulp and paper manufacturing process and the product quality may be hindered.

  In such a case, it is important to appropriately manage the effective concentration of the slime control agent in the system. In the slime control agent that utilizes the oxidizing power of hypochlorite, the residual by the colorimetric method such as the DPD method. A control system using an oxidation-reduction potential (ORP) measurement that uses concentration measurement and can automatically control the addition of a slime control agent more rapidly has also been proposed (see Patent Document 3). However, these methods are affected by factors other than microorganisms, such as inflow of a reducing agent from the bleaching process, and generally have disadvantages such that they cannot be applied to organic slime control agents.

  On the other hand, the effect of the slime control agent is also determined by measuring the number of bacteria in the target process water. In general, a method of measuring the number of viable bacteria in process water using a bacterial medium or a fungal medium is used, but the culture requires 3 days for bacteria and 5 days for fungi. Therefore, there is a drawback that the effect of the slime control agent cannot be judged quickly and an appropriate measure cannot be taken. In addition, the measurement of the number of bacteria also has a problem in that the medium to be used differs depending on the target bacteria.

  In addition, there is a method of measuring the amount of slime adhesion by hanging a stainless steel plate in the target water system as a method of judging the effect of the slime control agent, but it is necessary to suspend a number of stainless steel plates to grasp the continuous change Is not practical.

  In contrast to the current situation, the slime control agent is not affected by the type of slime control agent, the inflow material from the upstream process, or the bacterial species, and can be measured quickly and easily. A slime control method is strongly desired.

JP-A-8-176996 JP-A-11-512718 JP 2000-259933 A

  The object of the present invention is to reduce the influence of the type of slime control agent, the inflow material from the upstream process, or the bacterial species in the paper pulp manufacturing process to which the slime control agent is added, and can be measured by a quick and simple method. It is to propose a control status index and a slime control method using the index.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors can use an ATP (adenosine-triphosphate) amount in the process water of the paper pulp manufacturing process as the index to enable an appropriate slime control method. As a result, the present invention has been completed.

  That is, the invention according to claim 1 controls the addition amount of the slime control agent based on the concentration of ATP (adenosine-triphosphate) in the process water in the paper pulp manufacturing process to which the slime control agent is added. It is the slime control method of a paper pulp manufacturing process.

  The invention according to claim 2 is the slime control method according to claim 1, wherein the process water is at least one selected from pulp slurry, white water, and white water filtrate.

  The invention according to claim 3 is such that the concentration of ATP (adenosine-triphosphate) in the process water is such that the ATP (adenosine-triphosphate) extractant, luciferin, and luciferase are added to the process water. It is a slime control method in any one of Claim 1 or 2 obtained by measuring.

  By applying the method of the present invention, quick and appropriate slime control is possible in the paper pulp manufacturing process to which the slime control agent is added.

It is the schematic for demonstrating the whole structure in the Example of this invention. FIG. 6 is a diagram illustrating a set value of light emission amount in Example 1. It is a figure which shows transition of the light-emission amount and transition of the number of defective sheets in Example 1. It is a figure which shows transition of the microbe number and transition of the number of paper-forming defects in the comparative example 1.

  The present invention is a slime control situation that is less affected by the type of slime control agent, the inflow material from the upstream process, or the bacterial species in the pulp and paper manufacturing process to which the slime control agent is added, and can be measured by a quick and simple method. This is a slime control method that uses the amount of ATP (adenosine-triphosphate) in process water as an index of the process.

  The amount of ATP (adenosine-triphosphate) in the process water is determined so that ATP (adenosine-triphosphate) is extracted from the microorganisms present in the sample obtained from the process water. It can be determined by measuring the amount of luminescence obtained by adding luciferin and luciferase after adding the extractant to the sample water. This measurement is based on the enzyme reaction shown below (luciferin-luciferase reaction), in which ATP (adenosine triphosphate) assists luciferase and calcium ions or magnesium ions in the presence of luciferin and oxygen. It changes into AMP (adenosine monophosphate) and pyrophosphate by reacting as a catalyst. At the same time, luciferin is also oxidized and becomes fluorescent when converted to oxyluciferin. Since the amount of fluorescence emission is proportional to the amount of ATP present in the sample, a calibration curve relating the concentration of ATP (adenosine-triphosphate) and the amount of luminescence previously prepared with an ATP (adenosine-triphosphate) standard reagent. Can determine the amount of ATP (adenosine-triphosphate) in the sample. Since the amount of ATP can be calculated from the amount of luminescence in this way, it can be said that the amount of luminescence represents the amount of ATP (adenosine-triphosphate). This light emission amount is represented by a relative light emission unit (RLU).

  A commercially available measuring instrument can be used for measuring the amount of luminescence, for example, AccuPoint manufactured by NEOGEN CORPORATION, Lumitester manufactured by Kikkoman Corporation, OR-100 manufactured by Organo Tokyo Co., Ltd., etc. can be used. The luciferin and luciferase to be used can be obtained from fireflies, deep sea fish, microorganisms, etc., respectively. In the present invention, any of the above may be used, and a commercially available measurement reagent kit (trade name, manufactured by Kikkoman Corporation). : Lucifer 250 Plus) may be used.

  The amount of luminescence obtained by the luciferin-luciferase reaction is the total amount of free ATP (adenosine-triphosphate) contained in the process water and ATP (adenosine-triphosphate) extracted from the microorganism, When ATP (adenosine-triphosphate) elimination reagent is added to water and then ATP (adenosine-triphosphate) extractant, luciferin and luciferase are added, the amount of luminescence is ATP (adenosine-triphosphate) extracted from the microorganism. Acid) only. When the number of viable bacteria is the target of measurement as in the food industry, it is meaningful to measure only ATP (adenosine-triphosphate) extracted from the body of the microorganism, but in the paper pulp manufacturing process targeted by the present invention It is known that not only living microorganisms but also dead bodies of microorganisms are entangled with pulp fibers, pitch, scales, etc., so that slime is formed. It is considered that a more realistic index of slime control status can be obtained by quantitatively grasping the total amount of microorganisms included. Therefore, unless otherwise specified, ATP (adenosine triphosphate) elimination reagent is not added in the above luminescence measurement in the present invention.

  The ATP (adenosine-triphosphate) extractant added to the sample water is a drug used to extract ATP (adenosine-triphosphate) out of the cell before measurement, A surfactant is used.

  In the present invention, the amount of ATP (adenosine triphosphate) in the process water is used as an index of the slime control status in the paper pulp manufacturing process to which the slime control agent is added. The procedure for measuring the amount of ATP (adenosine-triphosphate) is simple and can be measured in a very short time. Since ATP (adenosine-triphosphate) is present in all living organisms, bacteria, yeast The amount of microorganisms in process water composed of mold and mold can be grasped as a whole.

  Due to the excellent properties of this ATP (adenosine-triphosphate) measurement method, the type of slime control agent used is not restricted, and the disadvantages of the bacterial count measurement method that requires a long time for measurement can be overcome.

  According to the present invention, the amount of ATP (adenosine-triphosphate) in one or more process waters selected from pulp slurry, white water, and white water filtrate of a paper pulp manufacturing process to which a slime control agent is added is specified. The addition amount of the slime control agent can be controlled so as to be less than the value. Specifically, pulp that exists in machine chests, mixing chests, various raw material storage tanks, broke raw material storage tanks, recovered raw material storage tanks, etc. after refining in the pulp and paper manufacturing process to which the slime control agent is added Selected from white water such as slurry, white water in white water silo, white water such as canal white water, seal pitch white water, surplus white water, clear white water treated with polydisc filter, white water filtered water such as reclaimed water filtered with sand filter etc. The amount of the slime control agent can be controlled so that the amount of ATP (adenosine-triphosphate) is measured with at least one sample and the amount is below a specific value.

  Since the specific value of the ATP amount set as an index for controlling the amount of slime control agent added varies depending on the papermaking items and manufacturing conditions produced in the paper pulp manufacturing process, it is a unique value determined by each paper machine. It is. Based on the transition of the amount of ATP during the continuous operation period of the paper machine, the number of “paper spots” that occurred during the operation period, and the result of judgment of contamination by open inspection observation of the equipment that is performed during regular repair of the paper machine The specific value of this ATP amount is determined.

  The slime control agent used in the present invention is not particularly limited, and is chlorine, chlorine dioxide, highly bleached powder, hypochlorous acid, sodium hypochlorite, ammonium hypochlorite, magnesium hypochlorite, hypochlorous acid. Potassium, hypobromite, sodium hypobromite, potassium hypobromite, calcium hypobromite, ammonium hypobromite, chlorinated or brominated hydantoins, chlorinated or brominated isocyanuric acid and its sodium salt Or potassium salts or inorganic bromides such as sodium bromide, ammonium bromide, calcium bromide, and ammonium chloride, ammonium sulfate, ammonium nitrate, etc., and oxidative compounds such as chlorine, chlorine dioxide, ozone, etc. Halogenous acid generating compound, further 2,2-dibromo-3-nitrate Lopropionamide (DBNPA), 2,2-dibromo-2-nitroethanol (DBNE), 1,4-bis (bromoacetoxy) -2-butene (BBAB), 5-chloro-2-methyl-4-isothiazoline- 3-one (Cl-MIT), 2-methyl-4-isothiazolin-3-one (MIT), 4,5-dichloro-1,2-dithiolane-3-one, 2-bromo-2-nitropropane-1 , 3-diol, 1,2-benzisothiazolin-3-one (BIT), etc., and these slime control agents may be used alone or in combination of two or more.

  By performing the method of the present invention at any time or continuously, it is possible to grasp the slime formation environment in the pulp slurry, white water, and white water filtrate of the paper pulp manufacturing process to which the slime control agent is added. That is, by measuring the amount of ATP (adenosine-triphosphate) in the water irregularly or periodically and controlling the amount of slime control agent added so that the measurement result is below a specific value, Slime control.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to a following example at all unless the summary is exceeded.

Example 1
Slime control based on the amount of ATP (adenosine-triphosphate) expressed by the amount of luminescence was performed for the fine paper making process (FIG. 1). In the paper making process, first, raw pulps such as the recovered raw material 1, the virgin pulp 2, and the broke raw material 3 are mixed in the mixing chest 4. The obtained pulp slurry 5 is sent to a machine chest 6, and pulp slurry prepared by adding various additives (not shown) is sent through a seed box 7 by a fan pump 8 and passed through a screen 9. Via, it is poured out on the wire from the stock inlet 10. The pulp slurry is dewatered by the wire part 11, and the white water, which is the water containing the collected fine pulp fibers, is collected in the white water silo 12, and a part of the white water 13 passes through the seal pit 14 to the polydisk filter 15. The other part is sent to the suction side of the fan pump 8 to be used for adjusting the concentration of the pulp slurry. In the polydisc filter 15, white water is filtered, and the recovered pulp fiber in the white water is sent to a recovered raw material tank (not shown) 16, while the white water filtrate 17 is a polydisc filter filtrate tank 18. And sent to the mixing chest 4 and various shower tanks (not shown) as dilution water.

  Here, the slime control agent is added to the polydisc filter filtrate tank 18 (medicine injection spot 19), and the amount of ATP (adenosine triphosphate) of the treated water is measured at the outlet of the polydisc filter filtrate tank 18. It was measured as the amount of luminescence when an ATP (adenosine-triphosphate) extractant, luciferin, and luciferase were added to the sample collected in 21 (white water filtered water 17). Similarly, the slime control agent is also added to the white water silo 12 (medicine injection site 20), and the amount of ATP (adenosine-triphosphate) is a sample (white water) collected at the measurement site 22 at the outlet of the white water silo 12. This was measured as the amount of luminescence when an ATP (adenosine triphosphate) extractant, luciferin and luciferase were added to 13).

Specific implementation conditions were as follows.
Implementation conditions (1) Target system: White water and filtered water of fine paper making process (2) White water pH: 7-8
(3) White water temperature: 30-45 ° C
(4) Slime control agent:
Ammonium sulfate and sodium hypochlorite were mixed immediately before addition at a ratio of nitrogen: chlorine = 1: 1 (molar ratio of chlorine and nitrogen in each component) using water as a solvent.
(5) Slime control agent addition place:
(6) Slime control agent addition frequency: 4 times / day (7) Slime control agent addition time: 10 minutes / times, or 15 minutes / times (8) Test period: 14 days (the target papermaking process is continuous operation for 14 days)

  First, a specific ATP amount value is set as a light emission amount as an index for controlling the addition amount of the slime control agent in the target process. The ATP emission amount (RLU) and the number of paper defects (pieces / day) of the samples collected from the measurement points 21 and 22 in FIG. 1 during the operation period in which slime control by the bacterial count measurement method is performed as in the comparative example described later. 2) is shown in FIG. From the results shown in FIG. 2, it was found that the ATP emission amount (RLU) should be set to 50000 RLU or less as an index for controlling the addition amount of the slime control agent in order to reduce the number of paper defects to 5 or less. It was.

  In the target process, the progress of Example 1 in which the ATP (adenosine triphosphate) luminescence amount (RLU) during the continuous operation period for 14 days was set to 50000 RLU or less was as follows.

  In Example 1, ATP (adenosine-triphosphate) luminescence was measured by white water collected from white water silo (measurement location 22) and polydisc filter filtrate water tank (measurement location 21) in the fine paper making process, and white water. The filtrate was used as a measurement sample. ATP (adenosine-triphosphate) extract was added to each measurement sample, and after adding a luminescent reagent, the amount of luminescence was measured with Lumitester C-110 within 20 seconds. Moreover, the measurement was continuously carried out once or twice a day.

  Although the addition time of the slime control agent at the start of operation was 10 minutes / time, the amount of ATP (adenosine triphosphate) luminescence in the white water and white water filtrate of the measurement sample increased on the fourth day of the operation. Since it increased further on the 5th day, the addition time of the slime control agent was extended to 15 minutes / time. As a result of carrying out a treatment for extending the addition time for 3 days thereafter, the increasing tendency of the ATP (adenosine triphosphate) luminescence amount was alleviated, so that the addition time was returned to 10 minutes / time from the 8th day. However, on the 10th day, the value of ATP (adenosine triphosphate) luminescence increased greatly again, so that the addition time was 15 minutes / time from the 10th day to the 14th day (at the end of the operation). An extended treatment was carried out, and the light emission amount was maintained below 50000 RLU throughout the entire operation period. As a result, the number of paper defects was 5 or less throughout the entire operation period.

  FIG. 3 shows changes over time in the amount of luminescence indicating the amount of ATP (adenosine-triphosphate) in Example 1 and the number of paper defects.

(Comparative Example 1)
In Comparative Example 1, slime control was performed by a method for measuring the number of bacteria based on the number of bacteria obtained by culturing a sample collected from the measurement site 22 in FIG. The other implementation conditions were the same as in Example 1, and the addition time of the slime control agent at the start of operation was 10 minutes / time. In Comparative Example 1, it was found on the 7th day that the number of bacteria increased greatly on the 4th day from the start of the operation, and it was not possible to cope with the rapid increase in the number of paper defects from the 6th day. From the 7th day onward, by extending the addition time of the slime control agent to 15 minutes / time, the number of paper-making defects decreased.

  FIG. 4 shows changes over time in the amount of luminescence indicating the amount of ATP (adenosine-triphosphate) in Comparative Example 1 and the number of paper defects.

  From the above results, it has been clarified that the slime control method of the present invention can be quickly and appropriately controlled by applying the slime control method of the present invention to the paper pulp manufacturing process to which the slime control agent is added. As a result, stable operation of the pulp and paper manufacturing process was achieved with a reduced number of paper defects.

1: Recovered raw material 2: Virgin pulp 3: Broke raw material 4: Mixing chest 5: Pulp slurry 6: Machine chest 7: Seed box 8: Fan pump 9: Screen 10: Stock inlet 11: Wire part 12: White water silo 13: White water 14: Seal pit 15: Polydisc filter 16: To recovered raw material tank 17: White water filtrate 18: Polydisc filter filtrate tank 19: Chemical injection location 20: Chemical injection location 21: Measurement location 22: Measurement location

Claims (3)

  In the paper pulp manufacturing process which has added the slime control agent, the slime control method of the paper pulp manufacturing process of controlling the addition amount of a slime control agent based on the density | concentration of ATP (adenosine triphosphate) in process water.   The slime control method according to claim 1, wherein the process water is one or more selected from pulp slurry, white water, and white water filtrate. The concentration of ATP (adenosine-triphosphate) in the process water is obtained by measuring the amount of luminescence when an ATP (adenosine-triphosphate) extractant, luciferin, and luciferase are added to the process water. The slime control method according to claim 1 or 2.

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