JPH03245894A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To treat fine fiber flocs enclosing bubbles to float to an upper layer part by a method wherein bentonite is added to and mixed with waste water containing floated pulp fibers and fine fiber flocs to flocculate and settle the pulp fibers and the fine fiber flocs. CONSTITUTION:By the use of bentonite, the insoluble substances in waste water, for example, pulp fibers, especially, fine fiber flocs enclosing bubbles (air) to float to an upper layer part or highly foamable chemicals are rapidly flocculated and settled to make it possible to obtain extremely excellent effect.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a wastewater treatment method using bentonite.

More specifically, the present invention relates to a method for treating wastewater containing floated pulp fibers and fine fiber flocs.

[Prior Art] There are various methods for treating various types of factory wastewater at present. A coagulation-sedimentation method is usually used to remove suspended solids from wastewater. Adsorption treatment using activated carbon is effective for removing surfactants, dyes, etc. from wastewater. Additionally, methods and techniques for removing anionic and cationic activators by adding a substance having the opposite ionicity have been disclosed.

[Problem to be solved by the invention]

However, the conventional techniques may have little effect depending on the substances present in the wastewater, or may not be put to practical use when the amount of wastewater is large or depending on the quality of the water, due to the high treatment cost. In addition, various methods and techniques such as those described above have been disclosed as methods for treating dissolved and suspended substances in wastewater, but insoluble substances, such as pulp fibers and fine fibers in paper manufacturing companies, especially foams ( There are no reports of effectiveness against fine fiber flocs that float to the upper layer by enveloping air).

Paper manufacturing companies often use highly foaming chemicals, causing pulp fibers, fine fibers, etc. to surface in wastewater, and are struggling to find countermeasures.

In addition, there are demands from paper companies that are increasingly turning white water into closed systems due to environmental issues, or that are at risk of becoming closed systems in the future, to overcome these problems.

The present invention provides a method for treating insoluble substances in the wastewater, such as pulp fibers and fine fibers in paper manufacturing companies, especially fine fiber flocs that float to the upper layer by enveloping bubbles (air).

[Means to solve the problem]

The present inventors have conducted intensive studies to develop a method for treating pulp fibers, fine fibers, etc. in wastewater, especially fine fiber flocs that float to the upper layer by enveloping bubbles (air). We have discovered a method in which bentonite is added and mixed with fibers, etc., and the floating pulp fibers, fine fibers, etc. are coagulated and precipitated.

That is, the wastewater treatment method is characterized by adding and mixing bentonite to wastewater containing floated pulp fibers and fine fiber flocs to coagulate and precipitate the pulp fibers and fine fiber flocs.

[Specific conditions for carrying out the invention]

The present invention will be described in detail.

It is sufficient that the bentonite used in the present invention is one that is generally commercially available and used industrially.

Bentonite is produced by the decomposition of volcanic ash or tuff glass, and its main component is aluminum silicate.
The composition is 5iOz 50-70%, AIz (h10-2
The clay is mainly composed of 7% montmorillonite, but in addition to the main mineral montmorillonite, it is divided into very fine particles that contain impurities such as proteinite, redstone, and fluorite as trace components, and it is divided into quite a distribution. It is extremely stable against heat.

Most of bentonite generally absorbs water naturally in water.
It swells and disintegrates to nearly 0 times, but some do not.

The bentonite used in the present invention not only coagulates and precipitates wastewater containing pulp fibers and fine fiber flocs floating on the wastewater, but also serves as an accelerator for sedimentation of pulp fibers and fine fiber flocs, which is an essential requirement of the present invention, and a floc-forming agent. ,
It also plays the role of an adsorbent.

In the present invention, in addition to bentonite, kaolin, slaked lime, silica, etc. can be used as sedimentation accelerators, and activated carbon, other white carbon, diatoms, etc. can be used as adsorbents, but they are not suitable for large-scale wastewater treatment due to cost. Bentonite is more preferable from the viewpoint of further speeding up the flocculation and sedimentation processing ability, and furthermore, bentonite is more advantageous because it has the abilities of a sedimentation accelerator, flonk generator, and adsorbent.

The amount of bentonite added to wastewater in the present invention is usually 50
~100.000 ppm, preferably 100-5
0.000 pp, more preferably 100 to 10.
000 ppm and stir. At less than 5 opp, the sedimentation promoting ability of bentonite is overcome by the buoyancy of fine fiber flocs that float to the upper layer by enveloping pulp fibers and fine fibers, especially bubbles (air). There is.

In addition, if the concentration exceeds 100,000 ppm, when coagulation-sedimentation treated pulp fibers and fine fibers are recycled as raw materials, the surface potential of bentonite will be negative, so the electrical balance in the system (zeta potential, etc.) will be affected. This is inconvenient because it is expected to crumble and cause problems when using paper strength enhancers, drainage improvers, retention aids, etc., and will also result in economic losses.

Furthermore, there is a problem with recycling coagulation-sedimentation treated pulp fibers and fine fibers as raw materials, as bentonite, etc. may act as a filler in paper products, causing problems with the paper-making process or paper properties. So I don't like it.

In addition, sulfuric acid band (Alt (SO4) 51
8H20) is dissolved, due to the positive effect of sulfuric acid band, bentonite interacts with pulp fibers, fine fibers, etc., and the fine fibers that float to the upper layer, especially enveloping bubbles (air), form flocs. It is effective in further increasing the sedimentation promotion ability of

Therefore, in addition to sulfuric acid, polyaluminum chloride, ferric chloride, and ferric chloride may be used as inorganic coagulation aids as needed.
Further effects can be expected by adding iron or the like.

In addition, organic flocculation aids include polyacrylamide as a nonionic agent, partial hydrolyzate of polyacrylamide as an anionic agent, acrylamide and α, β-unsaturated carboxylic acid, or their alkali metal salts or ammonium salts. Copolymers with cationic polyacrylamide, acrylamide and vinyl monomers having a tertiary amino group or organic or inorganic salts thereof, or copolymers with vinyl monomers having a tertiary amino group and quaternary Copolymers of quaternary ammonium salts obtained by reaction with grading agents and α, β-unsaturated carboxylic acids or their alkali metal salts or ammonium salts, urea-formalin resins, epoxy polyamide resins, etc. are added. It's okay.

Treatment is possible regardless of the temperature and pH of the wastewater to which bentonite is added.

〔Example〕

The present invention will be explained in detail below using Examples, but the present invention is not limited to these Examples.

Example 1 In a 200cc tall beaker, take 50cc of the pulp fibers and fine fiber flocs that floated to the top of the drainage water by enclosing bubbles (air), which is a problem in paper manufacturing companies, and dilute with city water to make a total of 200cc. and stirred thoroughly to ensure uniform dispersion. In this case, since it is pulp fiber and fine fiber flock that envelops bubbles (air),
After a few minutes, it was confirmed that it floated to the upper layer again and separated into two layers.

Next, the wastewater, which was confirmed to separate into the above two layers,
0.08 g (400 ppm) of bentonite was added and thoroughly stirred for 2 to 3 minutes so as to be uniformly dispersed, and the state of the suspension was observed while standing still. The time required for pulp fibers and fine fibers to settle or resurface was measured. The results are shown in Table 1.

Example 2 The same waste water as in Example 1 was used and the same operations were carried out, except that the amount of bentonite added was changed to 200 ppm. The results are shown in Table 1.

Example 3 The same waste water as in Example 1 was used and the same operations were carried out, except that bentonite was replaced with slaked lime and the amount added was changed to 400 ppm. The results are shown in Table 1.

Comparative Example 1 Bentonite was used as a general commercial flocculant (acrylamide type)
The same wastewater as in Example 1 was used and the same operations were performed except for the change. The results are shown in Table 1.

Comparative Example 2 The same waste water as in Example 1 was used and the same operation was carried out without adding bentonite. The results are shown in Table 1.

Example 4 The wastewater from the paper manufacturing company used in Example 1 was different from the pulp fibers and fine fibers that floated to the upper layer of the wastewater by enveloping bubbles (air), which was a problem at another paper manufacturing company. The same operation as in Example 1 was carried out except that the amount of bentonite added was changed to 1.00 ppm. The results are shown in Table 2.

Example 5 The same wastewater as in Example 4 was used and the same operations were carried out except that bentonite was changed to slaked lime.

The results are shown in Table 2.

Comparative Example 3 Bentonite was used as a general commercial flocculant (acrylamide type)
The same wastewater as in Example 4 was used and the same operations were performed except that the procedure was changed to . The results are shown in Table 2.

Comparative Example 4 The same waste water as in Example 4 was used and the same operation was carried out without adding bentonite. The results are shown in Table 2.

〔Effect of the invention〕

Conventional techniques have not been able to adequately treat insoluble substances in wastewater from paper manufacturing companies, such as pulp fibers and fine fibers, especially fine fiber flocs that float to the upper layer by enveloping bubbles (air).

However, by using the wastewater treatment method using bentonite of the present invention, insoluble substances in wastewater from paper manufacturing companies, such as pulp fibers and fine fibers, and especially fine fiber flocks or foams that surround bubbles (air) and float to the upper layer. It quickly coagulates and precipitates wastewater from paper manufacturing companies that use highly toxic chemicals, resulting in extremely excellent effects.

In particular, the wastewater treatment method of the present invention will be an extremely important method in the future, considering that white water in paper manufacturing companies will become increasingly closed due to wastewater regulation issues, global environmental issues, resource issues, etc.

Claims (1)

[Claims] 1) A wastewater treatment method characterized by adding and mixing bentonite to wastewater containing floated pulp fibers and fine fiber flocs to coagulate and precipitate the pulp fibers and fine fiber flocs.