JPH03119189A - Treatment of white liquor of paper mill - Google Patents

Abstract

PURPOSE:To provide a process for the treatment of white liquor of paper mill having remarkably improved clarifying effect of white liquor and applicable even to a high pH liquor by adding a surfactant having ammonium group and a specific clay mineral to white liquor of paper mill. CONSTITUTION:(A) A cationic surfactant having quaternary ammonium group and (B) a clay mineral composed mainly of montmorillonite are added to white liquor of paper mill to effect the separation and removal of suspending substance. The component A is preferably a quaternary ammonium surfactant having one or more 8-20C aliphatic chains. The system is preferably subjected to coagulation and precipitation treatment and/or flotation and separation treatment after the addition of the component A and the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating white water discharged in a paper manufacturing process. For more details, please refer to Manufactured.

The present invention relates to a white water treatment method in which fibrous and non-fibrous materials are collected and removed from white water discharged from a paper manufacturing process by a coagulation-sedimentation separation method or a flotation separation method, thereby recycling water for use.

[Conventional technology]

In the present invention, white water is a general term for filter furnace water discharged from the raw material treatment process in the papermaking process, wire water discharged from the papermaking process (paper machine water), and the like. In the paper manufacturing process, a large amount of white water is discharged, which includes not only fine fibrous substances but also minerals, coating agents, sizing agents, inks, pigments, wood resins, adhesives, and other contaminants from the raw material processing process. Contains material.

Conventionally, the activated sludge method, coagulation sedimentation separation method, etc. have been used as a general treatment method for this white water, and the sludge and wastewater are separated, and the wastewater is either discharged at a value that passes water quality standards, or The highly treated wastewater is recycled and used again as process water.

In addition, in closed raw material processing processes where water is actively recycled, flocculants and foaming agents are added to white water to prevent contamination of valves, generation of scale, slime, pitch, sticky substances, and corrosion of equipment due to water quality. A treatment method has been implemented in which suspended pollutants are added to the pollutants, air is blown into the resulting bubbles, and suspended pollutants are attached to the bubbles. Alternatively, a treatment method (pressure flotation sorting method) has also been implemented in which air-containing pressurized water is blown in to cause suspended matter to adhere to the generated bubbles for flotation sorting. In particular, the latter method is popular because it has low equipment costs and can meet a wide range of water quality requirements.

[Problem to be solved by the invention]

In order to obtain the optimum treatment effect with the above-mentioned coagulation-sedimentation method or flotation sorting method, it is most important to select the most suitable flocculant or foaming agent.

Common flocculants used in the coagulation-sedimentation separation method or flotation separation method described above include aluminum sulfate (alum), anionic, nonionic, and cationic polymers, and certain minerals. Used in combination.

However, conventional chemicals have a narrow range of usage conditions (especially p
(H, etc.), the effect is not sufficient, or it is necessary to select chemicals depending on the treatment method.

In view of the above, the main object of the present invention is to improve these drawbacks.

[Means to solve the problem]

That is, the present invention provides a treatment for papermaking white water, which is characterized in that a cationic surfactant having a quaternary ammonium group and a clay mineral mainly composed of montmorillonite are added to papermaking whitewater to separate and remove pollutants. The present invention provides a method.

As a result, the present invention was completed based on the discovery that the method is suitable for both a sedimentation treatment and flotation sorting treatment, is applicable to a wide range of conditions, and exhibits remarkable effects.

The present invention will be explained in detail below.

The surfactant having a quaternary ammonium group used in the present invention is an ammonium salt having one or two straight or branched long-chain hydrocarbon groups, and is generally represented by the following chemical formula. point to

R″ R-N″-R” ・X [R″ or R″ R-N′-R・X- R″ where R and R″ represent the same or different long-chain hydrocarbon groups, Preferably has 8 to 20 carbon atoms. For example, octyl, decyl, dodecyl, cetyl, stearyl, etc. are usually used. Groups other than the long chain hydrocarbon group bonded to the nitrogen represented by R" include lower hydrocarbon groups. , for example, methyl, ethyl, propyl, butyl, and the like. X- is a counter ion of quaternary ammonium, such as halogen (F-, CI-, Br-, r-), N O
Examples include iCH, COO-H8O, -, and the like.

Other ammonium salts include the above R or R''
A pyridinium salt having a long-chain hydrocarbon group represented by
Benzalkonium salts having a benzyl group can also be mentioned.

After adding a predetermined amount of these cationic surfactants,
Aggregates formed by adding a predetermined amount of clay minerals are separated from clear water by coagulation-sedimentation separation or flotation separation treatment. In this case, the cationic surfactant and the clay mineral may be added in any order, or may be added at the same time.

Typical clay minerals include montmorillonite clay minerals, kaolinite clay minerals, sepiolite, allophane, etc. The clay mineral used in the present invention has montmorillonite as its main component and has the chemical formula Al2O5.4.
S i Ot・H2 (This H2 is Na, Ca, Mg
It is a mineral represented by montmorillonite l-, ben)ite (where the exchange ions are mainly N
a, Ca), acid clay (some of the exchanged ions are H), etc.

The amount of cationic surfactant added varies depending on the degree of pollution of white water and the quality of pollutants, but it is usually 10 to 10,000.
ppm, preferably 100-1,00ppm.

The clay mineral has an amount of cationic surfactant of 115 to 10
0 times, preferably 2 to 10 times.

-a, the components in white water are negatively charged, and the amount of cationic surfactant added is determined by the amount of cations required for white water and the amount of cations required to bring the zeta potential of white water to O (JL). % or more is preferred. When the cationic surfactant is used in an amount of 125% or more of the amount to reach the isoelectric point, the amount of bentonite used is at least 2 of the amount of the cationic surfactant.
It is preferable to use twice or more.

The amount of cationic surfactant is 2 of the above cation requirement.
If it is less than 5%, the desired separation effect cannot be obtained. Conversely, even if this amount exceeds 125% of the cation requirement,
The effect will not be proportionally greater, and it will be disadvantageous in terms of cost.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

〔Example〕

The white water used in this example was filter furnace water after disintegrating used paper (white water 1), filter furnace water after flotation deinking in the waste paper processing process (white water 2), and filter furnace water after cooking beech wood kraft valves. This is washing water (white water 3). The composition of each is shown in Table 1.

Table 1 Required amount of thione: This is the amount of cations required to bring the zeta potential (value measured instead of the surface potential) of the components in white water to OmV. (Details of zeta potential and cation requirements are given in Paper Valve Technology Times, May 1986 issue, pages 49-54.) Add 880 ppm+ of stearyltrimethylammonium chloride (STMMC) to 1 liter of white water. (equivalent to the required amount of cations) and 4000 ppm of bentonite were added to adjust the pH.
A coagulation sedimentation process and a pressurized flotation sorting process were performed by adjusting the value to a predetermined value between 3 and 11.0.

Clear water was collected, and the absorbance of each sample at 280 nm in the ultraviolet region was measured. The reason why we did not measure in the visible range used for normal turbidity measurement was to also measure the removal effect of finer dissolved substances. The effect of treatment is the decrease rate (%) of the absorbance of treated water, with the absorbance of untreated water being 100.
It was expressed as Table 2 shows the results.

1/3 i of pressurized water adjusted to a pressure of 4 kg/can' was added to the white water while blowing according to Table 2-, and the clear water after 5 minutes was used as a sample for absorbance measurement. In slightly acidic conditions, an extremely high treatment effect of 85% or more can be obtained, with a pH of 11.

An extremely high treatment effect of 75% or more was obtained even at 0. As described above, it is characterized by having little dependence on 9H and exhibiting high effects in both coagulation sedimentation treatment and pressure flotation treatment.

Good 1'' Subwhite water 1, changing the amount of STM^C and bentonite, p
A coagulation-sedimentation treatment or a pressure flotation separation treatment was performed by adjusting the temperature to H4.5. The results are shown in Table 3.

When bentonite is used more than twice as much as STM 80, the effect of coagulation and precipitation treatment can be seen.

When STM^C becomes 220 pp or less (corresponding to 25% of the cation requirement of the white water used here), the reduction rate tends to decrease. That is, it is preferable to use a quaternary ammonium salt having an amount of 25% or more of the cation requirement of white water.

In the pressurized flotation process, air is removed from a compressor and mixed with octyltrimethylammonium bromide (JJ Masuyu White Water 1).
OTM 8) 800 ppm (approximately equal to the cation requirement 1) and bentonite 4000 ppm, or dicetyldimethylammonium bromide (DCDHΔB) 1
500 ppm of bentonite and 4000 ppm of bentonite were added, the pH was adjusted to 4.5, and coagulation-sedimentation treatment and pressure flotation treatment were performed. 59.9% for coagulation-sedimentation treatment,
36.1%, and 47°8% and 8% in pressure flotation treatment, respectively.
A treatment effect of 4.7% was obtained. The monoalkyl type quaternary ammonium salt fatty silver preferably has 8 or more carbon atoms. Quaternary ammonium salts of the di-long alkyl type give good results in pressure flotation treatments.

and 11'' 1 part white water, 1000 parts stearylpyridinium bromide
ppm (approximately the same amount as the cation requirement) and bentonite 4
000 ppm was added to adjust the pH to 4.5 and a similar experiment was performed. The coagulation sedimentation treatment achieved an effect of 80.1%, and the pressure flotation treatment achieved an effect of 81.3%.

11” Sub-white water 1, STM^cB so ppm and acid clay 40
When a similar experiment was carried out by adding 00 pp+s and adjusting the pH to 4.5, the 11-collection sedimentation treatment was 88.0% effective, and the pressure flotation treatment was 89.4% effective.

11" Add 300 ppll STM^C (approximately the same amount as the cation requirement) and 1400 ppm bentonite to Tamahakusui 2 to adjust the pH to 4.5, or add 800 ppm to Hakusui 3.
ppm of STM^C (approximately the same amount as the cation requirement) and 3
When a similar experiment was conducted by adding 500pp+* of bentonite and adjusting the pH to 9.0, the effects of coagulation and sedimentation treatment were 85.4% and 89.7%, respectively, and the effects of pressure flotation treatment were 84.8%, respectively. %, 86.5%.

Le 1 Add 880 ppTa of stearyltrimethylammonium chloride (STM^C) to white water 1 and adjust the pH to 4.5.
A coagulation sedimentation treatment or a pressurized flotation sorting treatment was performed with the adjustment adjusted to 6. As a result, the reduction rate for each was 3%.

When a similar experiment was carried out by adding bentonite 4 QOOppm to white water 1, the reduction rates due to coagulation sedimentation treatment and pressure flotation treatment were 51% and -75%, respectively.

The negative value of the treatment effect is mainly due to the absorbance of the treated water being greater than the absorbance of the starting white water due to agglomeration or unremoved filler.

That is, a sufficient effect cannot be obtained by using a cationic surfactant or bentonite alone.

myu white water 1, 7-7mu 1000ppm (j&'a addition fi
) Preferably, 120 ppm (optimal addition amount) of polyethyleneimine was added, the pH was changed, and coagulation-sedimentation treatment or pressure flotation treatment was performed. The results are shown in Table 4.

Looking at Table 4, it can be seen that the effect can only be obtained in the range of pH 5.0 or lower for alum or pH 8.0 or lower for polyethyleneimine.

Table 4 White water 1, STM^C 880ppm and kaolin 4000p
pm or STM^C880ppm and talc 4000
After adjusting the pH to 4.5 by adding pp11, a similar experiment was conducted. As a result, each -2
4.1% and 41.4%, respectively - in pressurized flotation treatment.
They were 30.8% and -130%.

Kaolin and talc, along with bentonite, are commonly used as adsorbents for pollutants in the paper manufacturing process.

〔Effect of the invention〕

In the present invention, as explained above, a cationic surfactant having a quaternary ammonium group and a clay mineral mainly composed of montmorillonite are added to white water, and coagulation-sedimentation treatment and/or flotation separation treatment is performed. This made it possible to significantly improve the clarification effect of white water. At the same time, conventionally, it was necessary to use flocculants separately in coagulation-sedimentation treatment or flotation sorting treatment, but the present invention is suitable for both, and can be applied under a wide range of conditions, especially in a high pH range.

Claims (1)

[Scope of Claims] 1. Paper manufacturing characterized by adding a cationic surfactant having a quaternary ammonium group and a clay mineral mainly composed of montmorillonite to papermaking white water to separate and remove contaminants. How to treat white water. 2. The method according to claim 1, wherein the cationic surfactant is a quaternary ammonium surfactant having at least one fatty chain having 8 to 20 carbon atoms. 3. The method according to claim 1, wherein a coagulation-sedimentation treatment and/or flotation sorting treatment is performed after adding the cationic surfactant and clay mineral. 4. The method according to claim 1, which is carried out using a cationic surfactant corresponding to 25% or more of the cation requirement of white water.