WO2021230038A1

WO2021230038A1 - Waste water treating agent and method for producing waste water treating agent

Info

Publication number: WO2021230038A1
Application number: PCT/JP2021/016415
Authority: WO
Inventors: 融松永; 雅彦伊東; 博幸本間
Original assignee: デクセリアルズ株式会社
Priority date: 2020-05-14
Filing date: 2021-04-23
Publication date: 2021-11-18
Also published as: TW202202451A; JP2021178290A; CN115397536A

Abstract

The present invention is a waste water treating agent that includes particles which contain plant powder and a flocculant polymer and that has a repose angle of 38 degrees or less.

Description

Wastewater treatment agent and manufacturing method of wastewater treatment agent

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.

As a conventional wastewater treatment agent, for example, a wastewater treatment agent having a granulated plant powder has been proposed for the purpose of being able to be suitably used for an automatic supply system capable of low cost and stable supply (for example, a wastewater treatment agent having a granulated product of plant powder). For example, see Patent Document 1).
Further, for the purpose of being able to be suitably used for an automatic supply system capable of stably and repeatedly and accurately supplying a wastewater treatment agent having a desired performance at low cost, a plant powder and a flocculant polymer are used. A wastewater treatment agent which is a granulated product containing a mixture has been proposed (see, for example, Patent Document 2).

In the technique described in Patent Document 1, in an automatic supply system in which a wastewater treatment agent is supplied from a hopper of a powder feeder to a melting machine by using the weight of the wastewater treatment agent, the wastewater treatment agent produces plant powder having poor fluidity. Since it is contained, bridges and rat holes are generated in the hopper of the dusting machine, and there is a problem that an aqueous solution containing a wastewater treatment agent having a certain concentration cannot be stably prepared.
Further, in the technique described in Patent Document 2, since the plant powder having poor fluidity and the flocculant polymer are simply mixed, the fluidity of the wastewater treatment agent is not improved, and the technique described in Patent Document 1 Similarly, there is a problem that bridges and rat holes are generated in the hopper of the dusting machine, and an aqueous solution containing a wastewater treatment agent having a certain concentration cannot be stably prepared.

Japanese Patent No. 6301802 JP-A-2015-231600

It is an object of the present invention to solve the above-mentioned problems in the past 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 plant powder, 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.

The means for solving the above problems are as follows. That is,
<1> Contains particles containing a plant powder and an agglutinant 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 0.55 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> The wastewater treatment agent according to any one of <1> to <3>, wherein the plant powder has an angle of repose of 47 to 57 degrees.
<5> Any of the above <1> to <4>, wherein the mass ratio of the plant powder to the flocculant polymer (plant powder: flocculant polymer) is 10%: 90% to 30%: 70%. It is a wastewater treatment agent according to.
<6> The wastewater treatment agent according to any one of <1> to <5>, wherein the plant powder contains a cationic component and the flocculant polymer contains an anionic component.
<7> A kneaded product preparation step for preparing a kneaded product by water-kneading the plant powder and the agglutinant polymer with a pressure kneader.
An extrusion molding step of extruding the kneaded product using a twin-screw molding machine to obtain a molded product.
It is a method for producing a wastewater treatment agent, which comprises.
<8> A primary drying step of drying the molded product so that the water content is 15% to 25% 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 <7>, which comprises.
<9> The method for producing a wastewater treatment agent according to <8>, wherein in the particle formation step, the generation rate of fine particles having a particle size of less than 250 μm is 18% 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 plant powder, and a hopper in an automatic supply system. It is possible to provide a wastewater treatment agent capable of preventing the generation 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 a plant powder and a flocculant polymer, and further contains other components as required.
The angle of repose of the wastewater treatment agent is 38 degrees or less, preferably 37 degrees or less. 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. Gently drop 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 plant powder 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. In the production method described in Prior Art Document 2, since the plant powder and the flocculant polymer are simply mixed, the plant powder and the flocculant polymer are not formed as integrated particles, and the angle of repose is increased. It cannot be below 38 degrees.

<Particles>
The particles include the plant powder and the flocculant polymer, and if necessary, other components.
In the particles, since the fibers of the fibrous plant powder and the flocculant polymer are entangled and physically bonded to each other, the plant powder and the flocculant polymer are integrated.
As a result, 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. Further, when the cationic component in the plant powder and the anionic component of the flocculant polymer are partially bonded electrochemically, the wastewater treatment agent is made into an aqueous solution by the user. It takes time to separate the plant powder and the flocculant polymer, and it is possible to prevent the water-insoluble component of the plant powder from separating and precipitating in a short period of time.
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.

-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, Japanese mustard spinach, 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 preferably 47 degrees or more and 57 degrees or less. This is because the particle size of the plant powder to be added as a raw material needs to be in an appropriate range (53 μm to 710 μm) in order to obtain the desired high aggregation characteristics and the effect of reducing the water content of sludge. However, when a plant with a low density is reduced to a fine powder of such a size, its fluidity is greatly deteriorated, and the angle of repose, which is one of the indicators of fluidity, shows a value of 47 degrees to 57 degrees. .. Further, when the particle size is further reduced, the angle of repose exceeds 57 degrees and shows a larger value, but when the particle size is reduced to this extent, the performance of the wastewater treatment agent containing the particle size is adversely affected, which is preferable. No.

The optimum value of the content ratio (mass ratio) of the plant powder and the flocculant polymer to the wastewater treatment agent changes depending on the type and concentration of the environmentally hazardous substance component in the wastewater to be treated and the type and concentration of coexisting substances that interfere with each other. We select products with the optimum compounding ratio for each type of wastewater. Among them, as the wastewater treatment agent for treating various heavy metals and fluorides, the content ratio (mass ratio) of the plant powder and the flocculant polymer is preferably 10%: 90% to 30%: 70%.

The plant powder preferably contains a certain amount of cationic component.

-Coagulant polymer-
As the flocculant polymer, if it retains a certain amount of anionic component and is completely water-soluble, it can be appropriately selected depending on the intended purpose. For example, acrylic acid acrylic amide copolymer (commonly known as PAM) can be selected. 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 38 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, many of the coagulant polymers used as the raw materials of the present invention can be used in the commercially available products, and the angle of repose of the coagulant polymer used in the study was 37 degrees.

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 0.55 g / mL or more, more preferably 0.60 g / mL or more. When the bulk density is 0.55 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. ..
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 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).

(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 plant 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, foreign materials such as the plant powder and the flocculant polymer are bonded and integrated. Is realized. Specifically, the water charged into the kneading facility is preferentially absorbed by the flocculant polymer, but is not absorbed by the plant powder. However, the water partially extruded from the flocculant polymer by the high shearing force of the pressurized kneader is absorbed by the plant powder, and as a result, both the plant powder and the flocculant polymer are partially extruded. It is possible to create a state in which it is dissolved in water. As a result, the above-mentioned physical bond (fibers are entangled) and electrochemical bond of the plant powder and the flocculant polymer are simultaneously generated to realize a state of integration.
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 mechanical property changes of the raw materials to be kneaded.

The amount of water added in the water-kneading is a factor that affects not only the kneading process but also the subsequent extrusion molding process and the drying process, so it is necessary to control it to an optimum value. Specifically, the amount is preferably about 1 times the total mass of the mixture of the plant powder and the flocculant polymer.

The number of rotations of the blades in the water kneading corresponds to the range of 10 rpm to 40 rpm. A high shearing force is required, but if the shearing force is too high, deterioration of the flocculant polymer will occur and the quality of the finished product will be impaired, so it is necessary to control the rotation speed and kneading time of the blades to the optimum values. There is.

<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.

Note that the material, etc. of the twin-screw screw molding machine that is compatible with the twin-screw molding machine changes depending on the shape of the blades of the screw. Further, since the degree of densification and productivity greatly change depending on the hole shape (hole diameter, number of holes, hole arrangement) of the die for extruding the kneaded material, it is necessary to optimize it according to the physical property value of the kneaded material to be charged. 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 15% to 25% to obtain a primary dried product. By drying the molded product so that the water content is 15% to 25%, 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 15% to 25% 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 were 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 18% 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. there were. 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. It was dried. The drying time at that time was 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, an increase in the amount of the chemical used directly leads to an increase in the cost of wastewater treatment, so the smaller the amount used, the more preferable.

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

<Preparation example 1 of plant powder>
All parts of Nagasaku Jute were dried by sun drying or the like until the water content became 10% or less.
Next, the dried plant was pulverized with a cutter mill or the like until the particle size distribution became 50 μm to 710 μm to obtain a plant powder.

(Example 1)
-Water kneading process-
After mixing 20% by mass of the plant powder and 80% by mass of a flocculant polymer (polyacrylamide, manufactured by SNF Co., Ltd., Flopan AN 926) to obtain a mixture, water was added to the obtained mixture. Was added in an amount of 95% by mass and kneaded with water for 3 minutes using a pressurized kneader 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 15% to 25%.
-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 10% by mass to 18% 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-
Particles having a particle size larger than 850 μm in the obtained wastewater treatment agent 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.

(Comparative Example 1)
After putting 30% by mass of the plant powder and 70% by mass of a flocculant polymer (polyacrylamide, manufactured by SNF Co., Ltd.) into a plastic bag, manually shake for 5 minutes or more to mix and drain. Obtained a treatment agent.

(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 the plant powder was changed to 20% by mass and the content of the flocculant polymer was changed to 80% 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 the plant powder was changed to 10% by mass and the content of the flocculant polymer was changed to 90% by mass.

(Comparative Example 4)
First, the water-kneading step was performed with a planetary mixer with the content of the plant powder being 20% by mass and the content of the flocculant polymer being 80% by mass (the amount of water added was about 230% with respect to the weight of the raw material mixture. Kneading time is about 10 minutes). Next, the kneaded product was manually torn into chunks of an appropriate size (φ30 to 50 mm), placed on a shelf with a net, and dried with a hot air dryer (at 80 ° C). 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.

(Comparative Example 5)
First, the water-kneading step was performed with a planetary mixer with the content of the plant powder being 20% by mass and the content of the flocculant polymer being 80% by mass (the amount of water added was about 230% with respect to the weight of the raw material mixture. Kneading time is about 10 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 was cut into a size of about 15 cm square, and the cut blocks were molded one by one into a sheet having a thickness of 7 mm or less using a stretching machine. The obtained 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.

First, the angle of repose and bulk density of the raw materials used in this study were measured. Next, the angle of repose and the bulk density of the wastewater treatment agents of Example 1 and Comparative Examples 1 to 5 were measured. In addition, the production lead time and production yield of the wastewater treatment agents of Example 1 and Comparative Examples 4 to 5 were evaluated. The results are shown in Table 1.

[Angle of repose]
The angle of repose was measured using a powder tester PT-X type (manufactured by Hosokawa Micron). Using the company's standard measurement conditions, the sample to be measured was dropped onto a circular pedestal via a funnel, and the angle formed by the slope when forming a mountain-shaped layer was measured.

[The bulk density]
The loose bulk density was measured using a powder tester PT-X type (manufactured by Hosokawa Micron). Using the company's standard measurement conditions, the wastewater treatment agent is gently poured from above into a 100 cc stainless steel cup and intentionally overflowed, and the weight of the cup contents when the portion protruding from the upper surface of the cup is removed. Was measured to determine the loose bulk density of the wastewater treatment agent at that time.

(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 plant powder 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

Contains particles containing plant powder and 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 0.55 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 angle of repose of the plant powder is 47 to 57 degrees.
The wastewater treatment agent according to any one of claims 1 to 4, wherein the mass ratio of the plant powder to the flocculant polymer (plant powder: flocculant polymer) is 10%: 90% to 30%: 70%. ..
The wastewater treatment agent according to any one of claims 1 to 5, wherein the plant powder contains a cationic component and the flocculant polymer contains an anionic component.
A kneaded product preparation step for preparing a kneaded product by adding water to a plant powder and an agglutinant polymer using a pressure kneader, and
An extrusion molding step of extruding the kneaded product using a twin-screw molding machine to obtain a molded product.
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 15% to 25% 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
7. The method for producing a wastewater treatment agent according to claim 7.
The method for producing a wastewater treatment agent according to claim 8, wherein in the particle formation step, the generation rate of fine particles having a particle size of less than 250 μm is 18% by mass or less with respect to all the particles.