JP2001079308A - Flocculating material for waste pulp in paper making waste water and treatment of paper making waste water using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flocculating material for waste pulp in paper making waste water and a treating method of the paper making waste water using the same. SOLUTION: The flocculating material is at least one kind of algae body itself of unicellular algae having a polysaccharide outside cover and the chemically modified or cross-linked one and the waste pulp suspended in the paper making waste water is adsorbed, flocculated and separated into a clarified water and flocculated algae-waste pulp-containing material. In such a case, containing no chemical flocculant, the clarified water is recycled as paper making water and the flocculated algae-waste pulp containing material is recycled for the adsorption and flocculation of the waste pulp in the paper making waste water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flocculant for waste pulp in paper wastewater and a method for treating papermaking wastewater using the flocculant.

[0002]

2. Description of the Related Art Waste pulp (short pulp) that has not been used for papermaking floats in papermaking wastewater, that is, wastewater after papermaking. Papermaking wastewater such as high-quality paper and art paper contains sizing agents, fillers, fixing agents, etc. along with paper strength or adhesives (polyacrylamide, etc.), but insulating paper for capacitors, filter paper, toilet paper, etc. When paper is made, the main solid content in the papermaking wastewater is fine fibers composed of polysaccharides such as cellulose and hemicellulose. If simple filtration is performed on papermaking wastewater after pure cellulosic papermaking in order to remove these fine fibers, clogging of the filter medium will occur early. Therefore, at present, generally, short pulp is flocculated and floated by adding a flocculant such as polyaluminum chloride, alum and the like to the waste water, stirring and leaving the pulp to collect, and is disposed of by disposal.

[0003]

The above prior art has a problem in that a large amount of liquid remaining after the recovery of waste pulp is a liquid containing a chemical flocculant as described above. . In other words, processing is necessary for reuse for papermaking, which increases the cost, and therefore has to be discharged.
This may lead to environmental pollution.

Accordingly, an object of the present invention is to provide a flocculant for short and small pulp which can be used as reclaimed water without special post-treatment of a liquid after removing waste pulp from papermaking wastewater, and a papermaking wastewater which can be treated by filtration. It is to provide a processing method.

[0005]

Means for Solving the Problems and Achieving the Object The present inventor has made various studies to solve the above problems and to achieve the above objects. First, the components of the short pulp that are problematic are mostly hemicellulose, which increases the yield,
Attention was paid to the fact that it is derived from hemicellulose left in an appropriate amount in papermaking pulp in order to promote beating and to enhance the adhesive force between fibers. Since hemicellulose is a polysaccharide, a substance having a high affinity for the polysaccharide was examined. As a result, from various viewpoints including safety, algae, in particular, unicellular algae, which led to selection of microalgae having an agar or a mucus-like thick coat made of polysaccharide on the surface thereof, When the algae were further examined, the polysaccharides constituting the envelope of the algae had a high affinity for polysaccharides such as cellulose and hemicellulose, and were adsorbed on floating waste pulp in papermaking wastewater to produce the waste pulp. The algae-waste pulp aggregate-containing liquid is easily separated into clear water and the alga-waste pulp agglomerates by means known per se, such as filtration, centrifugation, and stationary sedimentation. We have found that we have completed the present invention.

It is to be noted that the polysaccharide portion constituting the envelope of the algal body is chemically modified to introduce a functional group, and the polysaccharide portion is subjected to a crosslinking treatment so as to adsorb to waste pulp in papermaking wastewater. -It has also been found that it can lead to an improvement in coagulation ability.

Accordingly, the coagulant for waste pulp in papermaking wastewater according to the present invention is a single-cell algae alga body coated with a polysaccharide,
At least one of those obtained by chemically modifying the polysaccharide portion of the alga body and those obtained by subjecting the polysaccharide portion of the alga body to cross-linking treatment
It is characterized by being one kind.

[0008] On the other hand, the method for treating papermaking wastewater according to the present invention comprises an alga body of a single-cell algae having a polysaccharide as a sheath, a polysaccharide part of the algal body subjected to chemical modification, and a polysaccharide part of the algal body. At least one of which has been cross-linked,
The waste pulp is mixed with the papermaking wastewater in which the waste pulp is floating, and the waste pulp is coagulated by the adsorption of algal cells, and the alga-waste pulp aggregate-containing liquid is separated into clear water and alga-waste pulp aggregate-containing material It is characterized by doing.

The monocellular algae having a polysaccharide sheath and used as a flocculant for waste pulp in papermaking wastewater according to the present invention include Cyanophyta and Cyanophyta.
ceae), C belonging to the order Chroococcales
hroococcus , Microcystis and Gomphosphaeria , Aphanocapsa and Nos belonging to Nostocales
toc , Rhodophyta, Rhodophycea
e), Rhodell belonging to the order Pinophyrides (Porphyridiales)
a , Unequal plant phylum (Heterokontophyta), golden alga (Ch
rysophyceae), Urogrlena belonging to the order Ochromonadales, Haptophyta (Haptophyta), Haptophyceae (Haptophyceae), Purymnesiale (Prymnesiale)
s) belonging to Phaeocystis and green plant phylum (Chlorophy
ta), Sp belonging to the order Chlorococcales
Haerocystis and Gloeocystis belonging to the order of the Artemisia can be exemplified.

The reagents used for the chemical modification of the polysaccharide coat include acetalizing agents (monohydric or polyhydric aldehydes, epichlorohydrin, etc.), acetates, butyrates, methylates, aminating agents, acetaminolating agents. , A phosphoric acid esterifying agent, a nitric acid esterifying agent, a sulfuric esterifying agent or a dehydrating condensing agent. On the other hand, crosslinking reagents are glutaraldehyde, diamine, dicarboxylic acid, tricarboxylic acid,
It can be an acid anhydride, a diisocyanate or a polyisocyanate.

In the method of the present invention, as a means for treating a liquid containing agglomerates of alga bodies and waste pulp to separate them into clarified water and alga bodies-waste pulp aggregated substances, an algal collector as a filter, For example, a hollow fiber collecting device, a continuous centrifugal separator or the like can be used, and a static sedimentation method can be used although it is not preferable from the viewpoint of efficiency and the like.

Next, the present invention will be described in more detail with reference to test examples. Test Example 1 (Culture of single-cell algae and acquisition of alga bodies) Rhodella sp . Shaking culture was sequentially performed in a 500-ml Erlenmeyer flask, and finally aeration culture was performed in a 100-liter plastic tank. The medium was prepared by adding a commercially available artificial seawater mixture ["Aquamarine" (trademark) in tap water, adding a special additive (PESS) for culturing Phaaeocystis sp., And stirring the mixture. The culture temperature was set at 25 ° C, and light irradiation was performed using a white fluorescent lamp at an illuminance of 3000 lux for 16 hours and then off for 8 hours. The ventilation was set at 4 liters per minute. 28 days after the start of culture in 100 liters, filter using a hollow fiber alga collector (average pore size: 0.1 μm), and centrifuge (10,000 xg, 10 minutes)
As a result, an algal body (jelly-like material) with a wet weight of 1000 g was obtained.

Test Example 2 (Chemical modification of algal cells) Water was added to 100 g of the wet algal cells obtained in Reference Example 1 to make the volume 500 ml, and concentrated hydrochloric acid was added thereto to add acid (p.
H3), and then, while heating and stirring at 60 ° C, 0.1 ml of 37% formaldehyde solution (molecular ratio to sugar residue of alga was about 0.1) was added dropwise, and the mixture was stirred at 60 ° C for 30 minutes. did. Water was added to the obtained chemically-modified alga suspension to dilute it, and the treated alga was collected by centrifugation (10,000 × g, 10 minutes). The treated algal cells were resuspended in water, washed twice by centrifugation as above, and
0 g of a chemically modified algal body (jelly-like material) was obtained.

Test Example 3 and Comparative Test Example (Short Pulp Agglomeration Test in Papermaking Wastewater) Papermaking wastewater in which waste pulp floats at a concentration of about 100 ppm
(Wastewater after papermaking of insulating paper for capacitors) was introduced into the alga tank containing the alga bodies obtained in Reference Example 1 and stirred, and the waste pulp-algae-containing suspension was poured into a hollow fiber alga collector (average pore diameter). : 0.45 μm) to separate into substantially clear filtered water and a concentrated suspension containing algae-waste pulp aggregates. This filtered water can be reused as water for papermaking, and the concentrated suspension containing aggregates of waste pulp and algal bodies can be circulated and returned to the algae tank and reused. . The amount of wet algal cells required to treat paper pulp wastewater containing waste pulp per 1 m ³ is about 1 g.

On the other hand, the papermaking wastewater was directly led to the hollow fiber alga collector (average pore size: 0.45 μm).
Waste pulp penetrated into hollow fibers as filter media and clogged at an early stage, making continuous filtration impossible.

The above fact is that the alga bodies having a polysaccharide coat are adsorbed on the short pulp in the wastewater of papermaking to aggregate the short pulp, whereby the short pulp and the alga bodies are combined into a mass, This clearly shows that the hollow fiber is not clogged.

[0017]

According to the present invention, waste pulp in papermaking wastewater, that is, fine pulp that has not been used in papermaking, is almost impossible to remove because filter media is clogged at an early stage by simple filtration. The waste pulp was removed, and the liquid after removal of the waste pulp contained a chemical flocculant, so that it could not be cost-effectively reused as papermaking water. However, alga bodies having a polysaccharide coat are used as a flocculant in the present invention, and the alga bodies can be adsorbed to the waste pulp in the papermaking wastewater to coagulate the waste pulp. It can be separated into water and algae-waste pulp agglomerates. In this case, since the clarified water does not contain a chemical flocculant, it can be reused as papermaking water.On the other hand, the algae-waste pulp flocculant contains waste pulp floating in papermaking wastewater. It can be reused for agglomeration.

Continued on the front page F term (reference) 4B065 AA83X BC48 BD06 BD26 BD38 CA54 4D015 BA10 BA19 BB05 CA05 DB31 EA32 EA35 EA39 4D062 BA10 BA19 BB05 CA05 DB31 EA32 EA35 EA39

Claims (2)

[Claims] An algal body of a unicellular algae having a polysaccharide as a coat,
At least one of those obtained by chemically modifying the polysaccharide portion of the alga body and those obtained by subjecting the polysaccharide portion of the alga body to cross-linking treatment
One type of coagulant for short and small pulp in papermaking wastewater. 2. An algal body of a unicellular algae having a polysaccharide as a coat,
At least one of those obtained by chemically modifying the polysaccharide portion of the alga body and those obtained by subjecting the polysaccharide portion of the alga body to cross-linking treatment
One type is mixed with papermaking wastewater in which waste pulp is floating, and the waste pulp is agglomerated by the adsorption of algae, and then the liquid containing the algae-waste pulp aggregate is purified water and the alga-waste pulp A method for treating papermaking wastewater, comprising separating the wastewater into coagulated contents.