JPS6034882B2 - Method for separating organic substances dissolved in water - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for separating organic substances dissolved in water from water by adsorbing them to the adsorbent using a magnesia-based adsorbent.

Conventionally, it has been known to use a magnesia-based adsorbent as an adsorption treatment agent to separate and remove organic and inorganic substances contained in water.

For example, in Tokusei Publication No. 53-4835, it is shown that organic substances are adsorbed and removed using a magnesia-based adsorbent, and in JP-A-53-114791, inorganic substances are removed using a magnesia-based adsorbent. JP-A No. 53-114792 discloses a method of adsorbing and separating surfactants using a magnesia-based adsorbent, and Tokusei No. 53-45054 discloses that magnesia A method is presented for treating wastewater containing inorganic and organic substances using a system adsorbent in a series of coupled steps including an adsorption step, an adsorption separation step and an adsorbent regeneration step. Furthermore, magnesia-based adsorbents are also used as adsorbents for removing colored impurities from rice bran liquid and stevia extract. By the way, when removing organic substances contained in dissolved form in raw water using a magnesia-based adsorbent as described above, when the content of the organic substances becomes high, the adsorption efficiency deteriorates, and
The filtration properties of the adsorbent after adsorption treatment are poor, and when the adsorbent is separated from water by filtration, it becomes difficult for the filtrate to pass through the cake, and the filtration cake that has adsorbed organic matter becomes As time passes, significant heat is generated and a curing reaction occurs, making recycling difficult.

The present inventors have attempted to solve the above-mentioned problems that occur when using a magnesia-based adsorbent to adsorb raw water in which a relatively large amount of organic matter is dissolved. We have discovered that by setting the treatment temperature in a specific range of 30 to 75 oo, the adsorption efficiency is significantly improved, and the filtration efficiency when filtration of the adsorbent after the adsorption treatment is also significantly improved. He has completed his invention.

That is, according to the present invention, in a method for separating an organic substance from water in which at least 0.5% by weight of the organic substance is dissolved by adsorbing the organic substance to a magnesia-based adsorbent, 0% of the magnesia-based adsorbent is added to the organic substance. Provided is a method for separating organic substances dissolved in water, characterized in that the magnesia-based adsorbent is used at a ratio of .5 to 2 times by weight, and the adsorption of organic substances to the magnesia-based adsorbent is carried out at a temperature of 30 to 75°C. . The magnesia-based adsorbent used in the present invention is publicly known as described above, and it is a magnesium compound that can form magnesia by thermal decomposition such as magnesium hydroxide, magnesium carbonate, and basic magnesium carbonate (magnesium hydroxy carbonate). The adsorbent contains magnesia, which is formed by thermal decomposition, as the main component.

That is, inorganic fine particles such as alumina, silica, kaolin, ferric oxide, calcium oxide, perlite, zeolite, bentonite, diatomaceous material, etc. are added to the magnesia in appropriate amounts, usually 5%. It is possible to use a mixture containing % by weight or less. Magnesia-based adsorbents are powders, generally with a particle size of 30 to 2.
00 mesh, preferably 60 to 90 mesh, but can also be used in pellet form if necessary. In order to adsorb and separate organic and/or inorganic substances contained in water using a magnesia-based adsorbent, raw water may be brought into contact with the magnesia-based adsorbent.

As the contact method in this case, a column method or the like may be employed, but generally a method of adding and mixing adsorbent powder to raw water is employed. In this case, the adsorbent can be added as a powder or as a slurry of 5 to 5% by weight. In the present invention, when performing the adsorption treatment, the magnesia-based adsorbent is used at a ratio of 0.5 to 2 times the weight of the organic substance dissolved in water, and the adsorption treatment temperature is set at 30 to 75 oo, preferably 40 oo.
Specify within the range of ~60°C. In wastewater treatment using conventional magnesia-based adsorbents, the adsorption treatment is usually carried out at room temperature, and the amount of magnesia-based adsorbent used is usually 2 weight or more relative to the dissolved organic substance.
For raw water containing a high concentration of organic substances as in the present invention, 30 to 75 q
It is not known to perform adsorption treatment under a specific temperature condition of 0. Of course, it is possible to use a larger amount of adsorbent than the above range, but in this case, the amount of adsorbent consumed will increase, the adsorption efficiency will deteriorate, and the scale of equipment such as filtration equipment will also increase. Therefore, this is not preferable from the viewpoint of process economics. In addition, the amount of dissolved organic substances in the present invention is determined by drying sample water at 105°C until it reaches a constant weight, measuring the solid content A, and then calcining the solid matter at 600°C (20°C) and calculating the remaining amount. The clear amount B is measured and is the value obtained by subtracting the residual amount B from the solid content amount A. When carrying out the present invention, a flocculant may be added as necessary depending on the type of raw water. In this case, a commonly used flocculant such as a polymer flocculant is used, and the amount thereof is usually 1/1 by weight relative to the adsorbent.
The range is from 0000 to 1'500. The adsorption treatment can be carried out in either a batch or continuous manner, and can be carried out in a single stage or in a multistage manner. The adsorbent after the adsorption treatment is separated from the treated water in the form of a slurry with an adsorbent concentration of 5 to 5% by weight, but a portion of this can be recycled to the adsorption step if necessary.

The slurry-like adsorbent separated from the treated water is dehydrated by solid-liquid separation means such as filtration or centrifugation, and the water content is reduced to 30-30.
After forming a cake with a cloud content of 7% by weight, preferably 30-5% by weight, it is transported to a regeneration furnace as required, where 4% by weight is formed.
00 to 700 o'clock, preferably 500 to 650 o'clock, and recycled. The calcination in this regeneration can be carried out in air, but preferably the first 10 to 3
0 minutes is in an atmosphere with little oxygen (oxygen concentration 0 to 10% by volume)
) and then firing for 10 to 30 minutes each in an atmosphere with sufficient oxygen (oxygen concentration 10 to 25% by volume).
The adsorbent thus regenerated has almost completely returned to its state before use. This regenerated adsorbent passes through a cooler and a storage hopper and is reused as an adsorbent. In the present invention, when the adsorbent slurry after adsorption treatment is dehydrated by filtration or centrifugation to form a filtration cake, the filtration rate is significantly increased.

That is, when treating raw water containing high concentrations of organic substances using conventional methods, it is necessary to react for a long time (4 to 6 hours).
The adsorbent reduces its adsorption activity before performing a sufficient adsorption reaction with the organic substance, and a considerable amount (usually 10 to 3% by weight)
In the dehydration process, the resulting filtration cake becomes a filtration cake with poor water permeability, which not only makes cleaning difficult but also takes time. This was accompanied by a significant fever. As a result, even when the cake was dehydrated and dried and then recycled by firing, it took time to crush the exothermically hardened plate-shaped cake and the firing was likely to be insufficient. However, in the case of the uninvented method, since the adsorption treatment is performed under the above-mentioned specific conditions, the adsorbent performs a sufficient adsorption reaction with the organic substance, and the unreacted portion is significantly reduced. As a result, the problem of heat generation as described above does not occur, and smooth dehydration operation becomes possible. In the present invention, raw water containing dissolved organic substances at a relatively high concentration is advantageously applied as the raw water to be supplied to the adsorption treatment.

Of course, it is also applicable to raw water containing low concentrations of organic substances, but conventional methods can also be used to treat such raw water economically, and the method of the present invention is particularly applicable. Not needed. The present invention generally comprises at least 0.5% by weight of dissolved organic material, especially 1.5% by weight. Applicable to raw water or concentrated water containing organic substances in an amount of % by weight or more. Such raw water or organic substance concentrated water includes waste liquids such as pulp cooking waste liquid, pulp bleaching waste liquid, highly concentrated pulp washing water, and organic substances used in impurity removal processes such as rice bran purification treatment and stevia leaf extract treatment. The containing liquid to be treated can be mentioned. Next, the present invention will be explained in more detail with reference to Examples. Example 1 As raw water, 0.0% was added to the cooking waste obtained by cooking birch wood using the SCP method. A diluted solution was used by adding a large amount of water.

This raw water contained 4.5% by weight of dissolved organic substances. Next, 8% by weight (1.8 times the weight of the dissolved organic substance) of lightly calcined magnesia (firing temperature: 50,000℃) is added to this raw water, and the mixture is heated at a temperature of 0 to 9,000℃ for 60 minutes. Adsorption treatment was performed using Next, the obtained treated water is subjected to sedimentation treatment, the adsorbent is recovered as a slurry in the lower layer (slurry concentration 15-2% by weight), and the treated water is recovered as a liquid phase in the upper layer, and its organic substance content is examined. Ta. Next, the adsorbent slurry recovered as described above was dehydrated by filtration to form a cake having a moisture content of 50 to 6% by weight.

Next, Table 1 shows the evaluation results of the removal rate of colored organic matter (removal rate of 457 nm absorption chromatic component) of the treated water and the filtration property of the adsorbent in the dehydration process in relation to the adsorption treatment temperature.

Table 1 For comparison, experiments were conducted in the same manner as above, except that according to the conventional method, room temperature (2000) was adopted as the treatment temperature, and one weight of adsorbent was borrowed for the amount of organic matter in the raw water. I did it.

The results are shown in Table 2 in relation to the results of the present invention. In Table 2, the adsorption effect indicates the amount of organic matter adsorbed by the adsorbent per night.

From the results shown in Table 2, it is clear that in the case of the present invention, despite the small amount of adsorbent used, it is significantly superior in terms of organic matter removal rate, adsorption efficiency, and filtration performance. .

In particular, in terms of filtration properties, the comparative examples were quite poor;
In addition, the filtration cake generates a large amount of heat, with a maximum temperature of 120°C.
However, in the case of the present invention, the heat generation of the filtration cake was small, and the temperature rose only by about 1 to 2°C. Table 2 Example 2 Absolutely dried Stevia leaves 2009 Add 3 liters of Moko water, 60
Extract with shaking at 0.00°C for 5 hours, separate the liquid, and add 2.0ml of water to the residue.
After adding for 6 nights and shaking and extracting at 60oo for 2 hours, after separating the liquid,
For the third extraction, rice bran was extracted for 1 hour at 6,000 yen with water at 2.6 pm.

These extracts were combined and concentrated under a reduced pressure of 4,000 °C to obtain a dark brown mother liquor with an organic matter concentration of 2.0%. A magnesia-based adsorbent was added to this liquid to adsorb and remove impurities greater than the sweet substances of Stevia. The optimal addition amount is the amount of dissolved organic matter), and the addition ratio may be the same amount. The stirring speed at this time was 1 hour, and strong mixing was performed using a magnetic roller.
The coloring impurities in the obtained filtrate were measured.

The measurement of colored impurities in this case was carried out using pure water as a target liquid and a color difference (ΔE) method using a 10-degree XYZ system according to JIS Z8727. In this case, the solution p at the time of measurement
H'ma was standardized to 7.0±0.10. The results are shown in the table below. The color difference (ΔE) of the stock solution before adsorption treatment was 81.
It was 96. Table 3

Claims (1)

[Claims] 1. A method for separating organic substances from water in which at least 0.5% by weight is dissolved by adsorbing the organic substances to a magnesia-based adsorbent, in which the magnesia-based adsorbent is used in an amount of 0.5 to 2 times the weight of the organic substance. At the same time, adsorption of organic substances to the magnesia-based adsorbent is controlled at 30 to 75°C.
A method for separating organic substances dissolved in water, which is carried out at a temperature of .