JP2021178291A - Wastewater treatment agent, and method for producing wastewater treatment agent - Google Patents

Abstract

To provide a wastewater treatment agent which is excellent in flowability while containing a number of components having poor flowability such as celluloses, and can prevent occurrence of bridges and ratholes in a hopper in an automatic supply system, and a method for producing a wastewater treatment agent.SOLUTION: A wastewater treatment agent contains particles containing cellulose acetate and a coagulant polymer, and has an angle of repose of 38 degrees or less.SELECTED DRAWING: None

Description

The present invention relates to a wastewater treatment agent and a method for producing the wastewater treatment agent.

In recent years, in the process of manufacturing various products in factories, a large amount of wastewater containing environmentally hazardous substances such as metal ions and fluorine ions has been generated as inorganic ions, and wastewater treatment agents are used to purify this wastewater. ing.
Since the wastewater treatment itself is carried out via a plurality of water tanks, the chemicals (wastewater treatment agents) supplied to each water tank are generally supplied in a liquid form, and are solid such as a flocculant polymer. The powdered chemicals are made into a starch syrup-like aqueous solution using a dedicated dissolution facility and then supplied to the treatment water tank. When the amount of wastewater to be treated is large or when the wastewater is treated by automatic operation, it is often the case that the melting equipment is equipped with a system for automatically supplying chemicals. In this case, in order to obtain a solution having a constant concentration, a facility equipped with a mechanism for quantitatively supplying a drug, which is a solid powder, by using its own weight and fluidity is widely used. If the amount of wastewater is small or the amount of wastewater to be treated fluctuates greatly, the conditions may be changed manually to dissolve the wastewater, but the above-mentioned automatic supply system is adopted because the on-site burden such as increased man-hours increases. However, there are many places.

Under these circumstances, the lower the water content of the dehydrated sludge generated after the dehydration treatment, the smaller the amount of waste to be disposed of and the reduction in disposal costs. Therefore, it is desired to highly dehydrate the sludge.
Therefore, for example, an inorganic sludge dehydrating agent for a filter press capable of reducing the water content of an inorganic sludge cake by using alkylene oxide has been proposed (see, for example, Patent Document 1). Further, a sludge dewatering aid made of viscose rayon, which is a fibrous material having a water content of 30% by weight to 80% by weight, has been proposed. Further, a method for dehydrating sludge by adding a dehydration aid and a polymer flocculant to organic sludge, mixing them, and then mechanically dehydrating the sludge has been proposed (see, for example, Patent Document 2).

Japanese Patent No. 6123158 Japanese Patent No. 4817431

An object of the present invention is to solve the above-mentioned problems in the prior art and to achieve the following objects. That is, the present invention is a wastewater treatment agent that contains a large number of components having poor fluidity such as cellulose, but has excellent fluidity and can prevent the generation of bridges and rat holes in the hopper in an automatic supply system. And to provide a method for producing a wastewater treatment agent.

In the prior art, a wastewater treatment agent having both an effect of reducing the water content of sludge and a high aggregation property, which is a combination of cellulose having excellent water repellency and a flocculant polymer, has been proposed. Such a wastewater treatment agent Contains a considerable amount of cellulose, which has poor fluidity and poor affinity with water, as one of the raw materials. There is a problem that it is difficult and the fluidity of the granulated product or the mixture tends to deteriorate.
The means for solving the above problems are as follows. That is,
<1> Contains particles containing cellulose acetate and a flocculant polymer,
It is a wastewater treatment agent characterized by having an angle of repose of 38 degrees or less.
<2> The wastewater treatment agent according to <1>, which has a bulk density of 0.46 g / mL or more.
<3> The wastewater treatment agent according to any one of <1> to <2>, wherein the angle of repose is 37 degrees or less.
<4> Any of the above <1> to <3>, wherein the mass ratio of the cellulose acetate to the flocculant polymer (cellulose acetate: flocculant polymer) is 40%: 60% to 60%: 40%. It is a wastewater treatment agent according to.
<5> A kneaded product preparation step in which cellulose acetate and an agglutinant polymer are hydrolyzed and kneaded using a pressure kneader to prepare a kneaded product.
An extrusion molding step of extruding the kneaded product using a twin-screw molding machine to obtain a molded product, and
It is a method for producing a wastewater treatment agent, which comprises.
<6> A primary drying step of drying the molded product so that the water content is 14% to 22% to obtain a primary dried product.
The particleization step of crushing the primary dried product to obtain particles, and
A secondary drying step of drying the particles and
The method for producing a wastewater treatment agent according to <5>, which comprises.
<7> The method for producing a wastewater treatment agent according to <6>, wherein in the particle formation step, the generation rate of fine particles having a particle size of less than 250 μm is 19% by mass or less with respect to all the particles.

According to the present invention, it is possible to solve the above-mentioned problems in the prior art and achieve the above-mentioned object, and it is excellent in fluidity while containing a large number of components having poor fluidity such as celluloses, and is a hopper in an automatic supply system. It is possible to provide a wastewater treatment agent capable of preventing the occurrence of bridges and rat holes in the inside, and a method for producing the wastewater treatment agent.

(Wastewater treatment agent)
The wastewater treatment agent of the present invention contains particles containing cellulose acetate and a flocculant polymer, and further contains other components as necessary.
The angle of repose of the wastewater treatment agent is 38 degrees or less (less than 38.5 degrees when considering the first decimal place; the same applies hereinafter), and 37 degrees or less is preferable. When the angle of repose is 38 degrees or less, the fluidity of the wastewater treatment agent is improved, and the generation of bridges and rat holes in the hopper in the automatic supply system can be prevented.
The angle of repose of the wastewater treatment agent can be measured using, for example, a powder tester PT-X (manufactured by Hosokawa Micron Co., Ltd.), and the wastewater treatment agent is measured via a funnel on a circular cradle. And measure the angle between the slope and the horizontal plane when the layer is formed in a mountain shape.

The wastewater treatment agent of the present invention is produced as particles in which the cellulose acetate and the flocculant polymer are integrated by being produced by using the method for producing the wastewater treatment agent of the present invention described later, and the angle of repose is 38. It will be less than the degree.

<Particles>
The particles include the cellulose acetate and the flocculant polymer, and if necessary, other components.
In the particles, the cellulose acetate and the flocculant polymer are integrated. When the cellulose acetate and the flocculant polymer are integrated, the fluidity of the wastewater treatment agent is improved, and the generation of bridges and rat holes in the hopper in the automatic supply system can be prevented.
The shape of the particles is not particularly limited as long as the angle of repose of the wastewater treatment agent is 38 degrees or less, and can be appropriately selected depending on the intended purpose. Examples thereof include substantially spherical, needle-shaped, and non-spherical. Be done. Among these, a substantially spherical shape is preferable because it has high fluidity.

-Cellulose acetate-
The cellulose acetate is a cellulose ester esterified by substituting a part of hydrogen of cellulose with an acetic acid group.

Most of the commercially available cellulose acetate product forms are in the form of films or fibers, and there are few product forms in the form of powder. However, in order to produce the wastewater treatment agent of the present invention, it is an essential condition that the form is powdery and the particle size is 1.5 mm or less (preferably 0.355 mm or less). In addition to that, since the true specific gravity of the material itself is light, the angle of repose of the available cellulose acetate powder is 48 degrees or more and 58 degrees or less.

The weight average molecular weight of the cellulose acetate is preferably 100,000 or more, more preferably 150,000 or more. The higher the weight average molecular weight, the higher the effect of reducing the sludge water content.
The weight average molecular weight of the cellulose acetate is obtained, for example, by converting the measured value by gel permeation chromatography into the molecular weight of the standard polymethyl methacrylate.

The cellulose acetate, which is one of the starting raw materials, is preferably in the form of powder or particles.
The particle size of the cellulose acetate is preferably 1,500 μm or less, more preferably 1,000 μm or less, further preferably 710 μm or less, and most preferably 355 μm or less from the viewpoint of product characteristics, due to restrictions on the production process. When the particle size is 1,500 μm or less, the sludge water content can be reduced.

The content of the cellulose acetate can be appropriately selected depending on the intended purpose, but is preferably 40% by mass or more and 60% by mass or less with respect to the wastewater treatment agent.

-Coagulant polymer-
The flocculant polymer has an effect of removing inorganic unnecessary substances in waste water, and can be appropriately selected depending on the intended purpose as long as it is completely water-soluble. For example, acrylic acid acrylate copolymer. A thing (commonly known as PAM) is preferable.
Examples of the PAM include those having a carboxylic acid salt in order to have anionic properties.
As the PAM, a commercially available product can be used, and examples of the commercially available product include Flopan AN913 (PAM having a carboxylate in the side chain) (both manufactured by SNF Co., Ltd.). Be done.

Most of the commercially available flocculant polymers have good fluidity, and most of them have an angle of repose of 40 degrees or less. This is because the manufacturer of the flocculant polymer controls its physical property values (bulk specific gravity and particle size) in order to ensure good fluidity. Therefore, there are many commercially available products that can be used as the flocculant polymer used as the raw material of the present invention, and the angle of repose of the flocculant polymer used in the study was 37 degrees.

The content of the flocculant polymer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 40% by mass or more and 60% by mass or less with respect to the wastewater treatment agent.

The mass ratio of the cellulose acetate to the flocculant polymer (cellulose acetate: flocculant polymer) is preferably 40%: 60% to 60%: 40%, more preferably 50%: 50%. When the mass ratio is 40%: 60% to 60%: 40%, both high cohesiveness and water content reducing effect can be achieved at the same time.

-Other ingredients-
The other components are not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include plant powder.
The plant powder is a powder of a plant.
The plant is not particularly limited as long as it is a plant capable of coagulating and separating inorganic unnecessary substances (nickel, copper, fluorine, etc.) in wastewater, and can be appropriately selected according to the purpose, for example, long. Examples include chorus capsularis, moroheiya, komatsuna, trefoil, mizuna, and spinach. Among these, Chosaku Huangma and Moroheiya are preferable.
Examples of the site of the plant include leaves, skins, stems, roots and the like, and among these, leaves and skins are preferable.

The angle of repose of the plant powder is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 47 degrees or more and 57 degrees or less.

The content of the plant powder is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0% by mass or more and 10% by mass or less with respect to the wastewater treatment agent. When the content is 0% by mass or more, the components contained in the plant powder promote the coagulation action between the microflocs, and coagulation and precipitation can be realized in a short time. On the other hand, if the content of the plant powder is too high, the content of the flocculant polymer component required for the agglutination action decreases, and the blending balance of each component becomes poor. Therefore, the content is 10% by mass or less. preferable.

The particle size of the wastewater treatment agent needs to be controlled to a particle size of 150 μm or more and 1 mm or less in order to secure high fluidity and solubility during use. The particle size distribution is more preferably 250 μm or more and 850 μm or less.
In principle, the particle size distribution of the wastewater treatment agent is preferably measured by a dry method, and can be measured by using, for example, Morpholigi G3 (manufactured by Malvern).

The bulk density of the wastewater treatment agent is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.46 g / mL or more, more preferably 0.51 g / mL or more. When the bulk density is 0.46 g / mL or more, the equipment used for dissolving the flocculant polymer can be diverted without modification, so that the initial cost required for introducing the wastewater treatment agent of the present invention can be reduced. can.
The bulk density of the wastewater treatment agent can be measured using a powder tester PT-X type (manufactured by Hosokawa Micron Co., Ltd.), which is an industry standard device, and 100 cc of the wastewater treatment agent is quietly placed in a 100 cc stainless steel cup. And measure the bulk density of the wastewater treatment agent at that time.

The CA separation rate (cellulose acetate separation rate) is preferably 10% or less, more preferably 5% or less. When the CA separation rate is 10% or less, it is possible to realize a wastewater treatment agent in which the amount of cellulose acetate powder not integrated with the flocculant polymer is small and the angle of repose and the variation in bulk density are small.
Here, the CA separation rate can be obtained as follows.

[CA separation rate]
7 g of the wastewater treatment agent as a measurement sample is put into 350 g of acetone and dissolved in an ultrasonic cleaner at 28 kHz, 30 ° C. to 40 ° C. for 10 minutes to obtain a solution. Next, the obtained solution is filtered using a qualitative filter paper (holding particle size: 6 μm) to obtain a residue. The obtained residue is dried at 80 ° C. for 30 minutes or more to completely evaporate and remove acetone in the residue, and then the mass X (g) of the dried residue is measured. In this measurement method, cellulose acetate dissolves in acetone, but the flocculant polymer and other components do not dissolve in acetone, and cellulose acetate separated from other components such as the flocculant polymer preferentially dissolves in acetone. It is a measurement method that utilizes the two properties of. As a result, the CA separation rate can be obtained based on the following formula.
CA separation rate (%) = (7-X) / 7 × 100

(Manufacturing method of wastewater treatment agent)
The method for producing a wastewater treatment agent of the present invention includes a kneaded product preparation step and an extrusion molding step, preferably including a primary drying step, a particleization step, and a secondary drying step, and if necessary, further other steps. Including the process. The wastewater treatment agent of the present invention can be suitably produced by the method for producing a wastewater treatment agent of the present invention.

<Kneaded product preparation process>
The kneaded product preparation step is a step of kneading the cellulose acetate powder and the flocculant polymer while adding water using a pressure kneader to prepare a kneaded product. By using a pressure kneader in the kneaded product preparation step, a high shearing force can be applied to the kneaded product, and as a result, the cellulose acetate powder and the flocculant polymer, which are different and weakly compatible materials, are bonded to each other.・ It is possible to integrate them.
Specifically, the water charged into the kneading facility is preferentially absorbed only by the flocculant polymer, and is not absorbed by the water-repellent cellulose acetate powder at all. Here, the water absorbed in the coagulant polymer is forcibly and uniformly permeated into the entire coagulant polymer by the high shearing force of the pressure kneader, so that all the coagulant polymers are in a semi-dissolved state. By making the flocculant polymer, which was a solid powder, into a semi-dissolved state, the flocculant polymer becomes a state like a high-viscosity adhesive, and the cellulose acetate powder is dispersed in a high-viscosity liquid called a flocculant polymer. A state can be created. By further kneading, the water-repellent and water-insoluble cellulose acetate powder is forcibly bonded to the flocculant polymer. As a result, cellulose acetate, which originally has poor affinity, and the flocculant polymer are strongly bonded and integrated.

In the present invention, in order to obtain a high shearing force, a study was conducted using a two-blade pressure kneader, and a desired result was found. On the other hand, in the case of a kneader that has been changed to a blade specification that increases the shearing force, such as three blades, there is a possibility that the same high shearing force can be obtained without pressurizing. It can be easily inferred that equivalent results can be obtained if used.
The number of blades of the pressure kneader is not particularly limited and can be appropriately selected depending on the purpose. However, if the number of blades is increased and the shearing force is increased too much, the finished product becomes over-kneaded. Since there is a risk of impairing the quality, two sheets are preferable when considering the balance.

The pressurizing lid of the pressurizing kneader is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include those that can be pressurized by using a pressurizing air cylinder. Since the pressure kneader has a pressure lid, it is possible to uniformly apply a shearing force to the kneaded product and suppress the scattering of dust generated during water kneading. The pressure of the pressure lid is preferably 0.6 MPa or more.

The temperature in the water-kneading is preferably 15 ° C. or higher and 40 ° C. or lower in order to suppress thermal deterioration and changes in mechanical properties of the raw material to be kneaded.

The amount of water added in the water-kneading is a factor that affects not only the kneading step but also the subsequent extrusion molding step and the drying step, so it is necessary to control it to an optimum value. Specifically, about 72% by mass is preferable with respect to the total mass of the cellulose acetate powder, the flocculant polymer, and other raw materials.

The rotation speed of the blades in the water kneading corresponds to the range of 10 rpm to 40 rpm. The water-kneading time is preferably, for example, 3 minutes to 8 minutes. High shearing force and kneading by the shearing force are necessary, but if the shearing force is too high or the kneading time is too long, the coagulant polymer will deteriorate and the quality of the finished product will be impaired. It is necessary to manage the number of rotations and the kneading time to the optimum values.

<Extrusion molding process>
The extrusion molding step is a step of extruding the kneaded product using a twin-screw molding machine to obtain a molded product. In the extrusion molding step, by extrusion molding while pressurizing the kneaded product using a twin-screw screw molding machine, densification of the kneaded product is promoted and the true specific gravity of the molded product can be improved. Due to this effect, the loosening bulk density of the finished product can be improved, and the wastewater treatment agent having high fluidity can be realized. Further, by continuously cutting the molded product into granules immediately after extrusion, the kneaded product can be densified and granulated at the same time, and the drying step (primary drying step and secondary drying step) and particle formation described later can be performed. The efficiency of the process can be improved, and the productivity of the wastewater treatment agent can be improved.

It should be noted that the material and the like suitable for the twin-screw molding machine vary depending on the shape of the blades of the screw and the like. In addition, the degree of densification and productivity vary greatly depending on the hole shape (hole diameter, number of holes, hole arrangement) of the die that extrudes the kneaded material, so it is necessary to optimize it according to the physical property values of the kneaded material to be added. There is. In the present invention, a twin-screw extruder designed for producing pellets for tire rubber is used, and the hole diameter of the die is φ3.5 mm.

The temperature in the extrusion molding is preferably, for example, 15 ° C. or higher and 40 ° C. or lower.
The rotation speed of the twin-screw in the extrusion molding is preferably, for example, 10 rpm or more and 36 rpm or less. When the rotation speed is 40 rpm or more, kneading in the twin-screw is accelerated, resulting in excessive kneading, and there is a risk of deteriorating the quality of the finished product.

<Primary drying process>
The primary drying step is a step of drying the molded product so that the water content is 14% to 22% to obtain a primary dried product. By drying the molded product so that the water content is 14% to 22%, the molded product has flexibility, so that physical damage to the primary dried product in the particle formation step described later can be suppressed, and the particles can be prevented. It is possible to suppress the generation of fine particles in the chemical conversion process.
In the primary drying step, it is necessary to dry the molded product (granular) so that the water content of the molded product is 14% to 22% at the same time without binding to each other to form a huge mass during drying. It becomes. Therefore, in the present invention, a vibration type fluidized dryer is used for continuous drying. The drying conditions at that time are a hot air temperature of 80 ° C. or lower and a drying time (residence time in the dryer) of 5 to 10 minutes.

<Particle process>
The particle formation step is a step of crushing the primary dried product to obtain particles, and the generation rate of fine particles having a particle size of less than 250 μm is preferably 19% by mass or less with respect to all the particles.
In the particle formation step, it is necessary to pulverize granules having a size of several mm into powder of 250 μm to 850 μm in one treatment. In addition, since the suitable crushing method differs depending on the hardness of the granules and the constituent materials, it is necessary to select a crushing machine that has both the required processing capacity and processability.
In the present invention, a multi-blade cutter mill and an air transport system are combined to continuously supply a certain amount of granules to a crusher for crushing.

<Secondary drying process>
The secondary drying step is a step of drying the crushed particles to a moisture content of 6% or less.
In the secondary drying step, it is necessary to constantly measure and monitor the temperature of the product in the dryer, control the hot air temperature and the drying time so that the product temperature does not rise above 80 ° C, and perform the drying process. be. Therefore, in the present invention, the fluidized bed dryer and the air transportation system are combined so that the product temperature becomes 80 ° C. or lower while sending hot air of about 100 ° C. to a product of 4 kg to 5 kg each time. Perform a drying process. The drying time at that time is 10 to 15 minutes.

<Other processes>
Examples of the other steps include a classification step and the like.
In the classification step, it is preferable to classify the dried particles by using a classifier such as a vibration sieving machine or a cartridge type sieving machine so that the particle size of a good product is 250 μm or more and 850 μm or less.

(How to use wastewater treatment agent)
As a method of using the wastewater treatment agent, an aqueous solution prepared by dissolving the wastewater treatment agent of the present invention in water at a predetermined concentration is applied to the wastewater after the addition of the inorganic flocculant, so that minute amounts of inorganic unnecessary substances in the wastewater are used. The particles are aggregated and settled and removed from the wastewater.
Examples of the inorganic unnecessary substance include an inorganic unnecessary substance having at least one of nickel, fluorine, iron, copper, zinc, chromium, arsenic, cadmium, tin, and lead.

The water purification method of the present invention will be specifically described.
Inorganic unwanted substances (nickel, chromium, copper, zinc, fluorine, etc.) to be removed are usually dissolved in wastewater in the form of ions. Therefore, a treatment for solidifying the ions is first performed using a neutralizing agent, a coagulant, or the like corresponding to each component to form microflocs. Next, an inorganic flocculant such as PAC (polyaluminum chloride) is added to improve the surface potential balance of the microfloc and promote the coagulation action to increase the size. However, since the flocs do not increase to a size that can be aggregated and settled in a short time only by adding the inorganic flocculant, the wastewater treatment agent solution of the present invention in which an aqueous solution of 0.1% by mass to 0.2% by mass is prepared. Add an appropriate amount. As a result, the microfloc grows to a size that can be aggregated and settled in a short time, and by separating and collecting only the precipitate, unnecessary substances in the wastewater are removed and purified wastewater is obtained. It is.
The amount of chemicals (neutralizing agent, inorganic flocculant, wastewater treatment agent of the present invention) used in performing the above-mentioned wastewater treatment varies greatly depending on the concentration of each component in the wastewater, the initial pH value, the amount of wastewater, etc. It is necessary to adjust the input amount according to the drainage of the water. However, the increase in the amount of the drug used is
The smaller the amount used, the more preferable it is, as it directly leads to an increase in wastewater treatment costs.

Hereinafter, examples of the present invention will be described, but the present invention is not limited to these examples.

(Example 1)
-Water kneading process-
Cellulose acetate (median diameter: 200 μm to 330 μm, weight average molecular weight (Mw): 170,000, made in China) 50% by mass and flocculant polymer (polyacrylamide, Flopan AN 926 manufactured by SNF Co., Ltd.) 50% by mass After mixing with% to obtain a mixture, 72% by mass of water was added to the obtained mixture, and the mixture was hydrated and kneaded for 5 minutes using a pressure kneader with two blades to obtain a kneaded product. ..
-Extrusion molding process-
The obtained kneaded product is extruded using a twin-screw extruder designed for producing pellets for tire rubber, and the molded product extruded from a die hole having a size (φ) of 3.5 mm is rotated. It was cut with a blade so that the length (L) was 5 mm or less.
-Primary drying process-
The obtained molded product is continuously controlled by using a vibration flow type dryer manufactured by Dalton Co., Ltd. so that the molded products (granular) do not bond with each other during drying to form a huge lump. Drying was carried out to obtain a primary dried product. The water content of the obtained primary dry matter was measured using an infrared moisture meter and found to be 14% to 22%.
-Particle process-
The obtained primary dried product was crushed with a multi-blade cutter mill manufactured by Horai Co., Ltd. to obtain particles. The generation rate of fine particles having a particle size of less than 250 μm when pulverized with a cutter mill was 12% by mass to 19% by mass with respect to all the particles.
-Secondary drying process-
The obtained particles were secondarily dried using a fluidized bed dryer manufactured by Dalton Co., Ltd. in order to eliminate adhesion and bonding between the particles. At this time, in order to prevent the product temperature from rising above 80 ° C., a temperature sensor was inserted inside the dryer to measure the product temperature, and batch processing was performed. The water content of the obtained secondary dry product was measured using an infrared moisture meter and found to be 6% or less.
-Classification process-
In the obtained wastewater treatment agent, particles having a particle size larger than 850 μm are removed by sieving with a nominal opening of 850 μm (mesh No. 20), and particles having a particle size smaller than 250 μm are removed with a nominal opening of 250 μm (mesh No. 60). ) Was removed by sieving to obtain a wastewater treatment agent having a particle size of 250 μm or more and 850 μm or less.

(Example 2)
In Example 1, the content of cellulose acetate was changed from 50% by mass to 47.5% by mass, the content of the flocculant polymer was changed from 50% by mass to 47.5% by mass, and the entire site of Nagasaku yellow hemp was changed. 1 A wastewater treatment agent was obtained in the same manner as above.

(Comparative Example 1)
Cellulose acetate (median diameter: 200 μm to 330 μm, weight average molecular weight (Mw): 170,000, made in China) 40% by mass and flocculant polymer (polyacrylamide, Flopan AN 926 manufactured by SNF Co., Ltd.) 60 mass After putting% in a plastic bag, it was manually shaken for 5 minutes or more to mix, and a wastewater treatment agent was obtained.

(Comparative Example 2)
In Comparative Example 1, a wastewater treatment agent was obtained in the same manner as in Comparative Example 1 except that the content of cellulose acetate was changed to 50% by mass and the content of the flocculant polymer was changed to 50% by mass.

(Comparative Example 3)
In Comparative Example 1, a wastewater treatment agent was obtained in the same manner as in Comparative Example 1 except that the content of cellulose acetate was changed to 60% by mass and the content of the flocculant polymer was changed to 40% by mass.

(Comparative Example 4)
Cellulose acetate (median diameter: 200 μm to 330 μm, weight average molecular weight (Mw): 170,000, made in China) 50% by mass and flocculant polymer (polyacrylamide, Flopan AN 926 manufactured by SNF Co., Ltd.) 50% by mass % Was added and kneaded with a planetary mixer (the amount of water added was about 180% with respect to the weight of the raw material mixture, and the kneading time was about 20 minutes). Next, the kneaded product was placed in a rectangular box, placed with a push lid, and pressure-molded under a pressure of 0.5 MPa over about 1 minute to obtain a block-shaped molded product. Further, this molded body is cut into a size of about 15 cm square, and the cut blocks are individually stretched (manufactured by Komatsu Industries Corp., 45t press machine) to obtain a sheet-shaped molded product having a thickness of 6 mm. rice field.
The molded product was placed on a shelf covered with a net and dried together with the shelf in a hot air dryer (at 80 ° C. for 20 hours or more). The lumpy dried product having a water content of 6% or less was pulverized in two stages with a cutter mill to form a powder. Finally, a wastewater treatment agent was obtained by classifying with a vibration sieve or the like so that the particle size distribution was 250 μm to 850 μm.

[Angle of repose]
The angle of repose was measured using a powder tester PT-X type (manufactured by Hosokawa Micron).
The sample to be measured was dropped on a circular pedestal via a funnel, and the angle formed by the slope when the layer was formed in a mountain shape was measured.

[The bulk density]
100 cc of wastewater treatment agent was gently placed in a 100 cc stainless steel cup, and the density of the wastewater treatment agent at that time was measured using a powder tester PT-X type (manufactured by Hosokawa Micron Co., Ltd.).

[Cellulose acetate separation rate (CA separation rate)]
7 g of the wastewater treatment agent as a measurement sample is put into 350 g of acetone and dissolved in an ultrasonic cleaner at 28 kHz, 30 ° C. to 40 ° C. for 10 minutes to obtain a solution. Next, the obtained solution is filtered using a qualitative filter paper (holding particle size: 6 μm) to obtain a residue. The obtained residue is dried at 80 ° C. for 30 minutes or more to completely evaporate and remove acetone in the residue, and then the mass X (g) of the dried residue is measured. In this measurement method, cellulose acetate dissolves in acetone, but the flocculant polymer and other components do not dissolve in acetone, and cellulose acetate separated from other components such as the flocculant polymer preferentially dissolves in acetone. It is a measurement method that utilizes the two properties of. As a result, the CA separation rate can be obtained based on the following formula.
CA separation rate (%) = (7-X) / 7 × 100

(evaluation)
<Supply stability>
When each wastewater treatment agent was put into a hopper with an angle of 60 degrees and an attempt was made to automatically supply it to the dissolution tank, it was evaluated whether stable supply could be achieved according to the following criteria.
-Evaluation criteria-
A: No bridge or rat hole is generated and stable supply can be continued. B: Although a bridge or rat hole is generated, by giving vibration to the hopper, the bridge or rat hole disappears and the supply is supplied. Can be continued C: Even if a bridge or rat hole is generated and vibration is applied to the hopper, the bridge or rat hole will not be eliminated and stable supply will not be possible.

<Manufacturing lead time>
The production lead time (production L / T) was measured from the time when the cellulose acetate and the flocculant polymer were weighed until the wastewater treatment agent was obtained.

<Manufacturing yield>
For the manufacturing yield, the finished product amount (weight) / total raw material input amount (weight) was measured.

Claims (7)

Contains particles containing cellulose acetate and a flocculant polymer,
A wastewater treatment agent characterized by having an angle of repose of 38 degrees or less. The wastewater treatment agent according to claim 1, which has a bulk density of 0.46 g / mL or more. The wastewater treatment agent according to any one of claims 1 to 2, wherein the angle of repose is 37 degrees or less. The wastewater treatment agent according to any one of claims 1 to 3, wherein the mass ratio of the cellulose acetate to the flocculant polymer (cellulose acetate: flocculant polymer) is 40%: 60% to 60%: 40%. .. A kneaded product preparation step for preparing a kneaded product by adding water-kneading cellulose acetate and an agglutinant polymer using a pressure kneader.
An extrusion molding step of extruding the kneaded product using a twin-screw molding machine to obtain a molded product, and
A method for producing a wastewater treatment agent, which comprises. A primary drying step of drying the molded product so that the moisture content is 14% to 22% to obtain a primary dried product, and
The particleization step of crushing the primary dried product to obtain particles, and
A secondary drying step of drying the particles and
5. The method for producing a wastewater treatment agent according to claim 5. The method for producing a wastewater treatment agent according to claim 6, wherein in the particle formation step, the generation rate of fine particles having a particle size of less than 250 μm is 19% by mass or less with respect to all the particles.