TWI886269B - Wastewater treatment agent and method for manufacturing wastewater treatment agent - Google Patents

Abstract

The drainage treatment agent of the present invention comprises particles containing plant powder and flocculant polymer, and has a repose angle of less than 38 degrees.

Description

Drainage treatment agent and method for producing the same

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

In recent years, a large amount of wastewater containing environmental load substances such as metal ions or fluorine ions as inorganic ions is generated in the process of manufacturing various products in factories. In order to purify the wastewater, wastewater treatment agents are used. Since the wastewater treatment itself is performed in a process passing through multiple water tanks, the reagents (wastewater treatment agents) supplied to each water tank are usually supplied in liquid form. For example, solid powder reagents such as flocculants and polymers are made into a watery aqueous solution using a dedicated dissolution device and then supplied to the treatment water tank. When the amount of wastewater to be treated is large or it is treated by automatic operation, in most cases, a system equipped with a system for automatically supplying the reagent to the above-mentioned dissolution device is used. In this case, in order to obtain a solution of a certain concentration, equipment equipped with a mechanism that uses its own weight and fluidity to quantitatively supply solid powder medicines is widely used. In addition, when the drainage volume is small or the variation of the treated drainage is large, sometimes the conditions can be changed manually to dissolve, but due to the increase in the number of steps and the increase in the burden on the site, the above-mentioned automatic supply system is mostly used.

As a conventional drainage treatment agent, for example, a drainage treatment agent having a granulated substance of plant powder has been proposed, the purpose of which is to be suitably used in an automatic supply system capable of stably supplying at low cost (for example, refer to Patent Document 1). In addition, a drainage treatment agent has been proposed, which is a granulated substance of a mixture of plant powder and a flocculant polymer, the purpose of which is to be suitably used in an automatic supply system capable of stably supplying a drainage treatment agent of required performance at low cost and with good repeatability accuracy (for example, refer to Patent Document 2).

The technology described in Patent Document 1 has the following problem: In the automatic supply system that uses the weight of the drainage treatment agent to supply the drainage treatment agent from the hopper of the powder feeder to the dissolving machine, since the drainage treatment agent contains plant powder with poor fluidity, bridges or rat holes will be generated in the hopper of the powder feeder, making it impossible to stably prepare an aqueous solution containing a certain concentration of drainage treatment agent. In addition, the technology described in Patent Document 2 has the following problems: Since the plant powder with poor fluidity is simply mixed with the flocculant polymer, the fluidity of the drainage treatment agent is not improved. Similar to the technology described in Patent Document 1, bridges or rat holes will be generated in the hopper of the powder feeder, and an aqueous solution containing a certain concentration of drainage treatment agent cannot be stably prepared. [Prior Technical Document] [Patent Document]

Patent document 1: Japanese Patent Publication No. 6301802 Patent document 2: Japanese Patent Publication No. 2015-231600

[The problem that the invention wants to solve]

The purpose of the present invention is to solve the above-mentioned problems in the past and achieve the following objectives. That is, the purpose of the present invention is to provide a drainage treatment agent and a method for producing the drainage treatment agent, which has excellent fluidity even if it contains a large amount of poorly fluid components such as plant powder, and can prevent the formation of bridges or rat holes in the hopper of the automatic supply system. [Technical means for solving the problem]

As a means for solving the above-mentioned problems, it is as follows. That is, ＜1＞ A drainage treatment agent characterized by comprising particles containing plant powder and flocculant polymer, and having a repose angle of 38 degrees or less. ＜2＞ The drainage treatment agent described in ＜1＞ above, having a bulk density of 0.55 g/mL or more. ＜3＞ The drainage treatment agent described in ＜1＞ or ＜2＞ above, having a repose angle of 37 degrees or less. ＜4＞ The drainage treatment agent described in any one of ＜1＞ to ＜3＞ above, wherein the repose angle of the plant powder is 47 degrees to 57 degrees. <5> A drainage treatment agent as described in any one of <1> to <4> above, wherein the mass ratio of the plant powder to the flocculant polymer (plant powder: flocculant polymer) is 10%:90% to 30%:70%. <6> A drainage treatment agent as described in any one of <1> to <5> above, wherein the plant powder contains a cationic component and the flocculant polymer contains an anionic component. <7> A method for producing a drainage treatment agent, characterized in that it comprises: a kneading step, which is to prepare a kneading material by adding water to the plant powder and the flocculant polymer using a pressure kneader; and an extrusion molding step, which is to extrude the kneading material using a twin-screw molding machine to obtain a molded product. <8> The method for producing a drainage treatment agent as described in <7> above, comprising: a primary drying step, which is to dry the molded product in such a way that the moisture content becomes 15% to 25% to obtain a primary dried product; a granulation step, which is to crush the primary dried product to obtain particles; and a secondary drying step, which is to dry the particles. <9> The method for producing a drainage treatment agent as described in <8> above, wherein, in the granulation step, the yield of fine powder with a particle size of less than 250 μm is less than 18% by mass relative to all particles. [Effect of the invention]

According to the present invention, the above-mentioned problems in the past can be solved and the above-mentioned purpose can be achieved; the present invention can provide a drainage treatment agent and a method for manufacturing the drainage treatment agent, and the drainage treatment agent has excellent fluidity even if it contains a large amount of components with poor fluidity such as plant powder, and can prevent the formation of bridges or rat holes in the hopper in the automatic supply system.

(Drainage treatment agent) The drainage treatment agent of the present invention contains particles containing plant powder and flocculant polymer, and further contains other components as needed. The repose angle of the drainage treatment agent is 38 degrees or less, preferably 37 degrees or less. If the repose angle is 38 degrees or less, the fluidity of the drainage treatment agent is improved, and the formation of bridges or rat holes in the hopper in the automatic supply system can be prevented. The repose angle of the drainage treatment agent can be measured, for example, using a powder tester PT-X (manufactured by Hosokawa Micron Co., Ltd.), so that the drainage treatment agent to be measured slowly falls from a funnel to a circular receiving platform, and the angle between the slope and the horizontal plane when the mountain-shaped layer is formed is measured.

The drainage treatment agent of the present invention is manufactured using the following method for manufacturing the drainage treatment agent of the present invention, thereby forming particles in which the plant powder and the flocculant polymer are integrated, and the repose angle is less than 38 degrees. In the manufacturing method described in the 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 into particles in which the plant powder and the flocculant polymer are integrated, and the repose angle is not less than 38 degrees.

<Particles> The particles contain the plant powder and the flocculant polymer, and other components as needed. In the particles, the plant powder and the flocculant polymer are integrated because the fibers of the fibrous plant powder and the flocculant polymer are intertwined and physically bonded. Thereby, the fluidity of the drainage treatment agent is improved, and the formation of bridges or rat holes in the hopper in the automatic supply system can be prevented. In addition, the cationic components in the plant powder and the anionic components of the flocculant polymer are partially electrochemically bonded, so that when the user makes the drainage treatment agent into an aqueous solution, it takes time to separate the plant powder and the flocculant polymer, which can prevent the water-insoluble components of the plant powder from separating and precipitating in a short time. The shape of the particles is not particularly limited as long as the repose angle of the drainage treatment agent is less than 38 degrees, and can be appropriately selected according to the purpose, for example, roughly spherical, needle-shaped, non-spherical, etc. Among them, roughly spherical is preferred in terms of high fluidity.

-Plant powder- The plant powder is obtained by making a plant into powder. As the plant, there is no particular limitation as long as it can condense and separate inorganic useless substances (nickel, copper, fluorine, etc.) in drainage, and it can be appropriately selected according to the purpose. For example, it can be listed: Corchorus olitorius, kelp, komatsuna, celery, Japanese celery, spinach, etc. Among them, Corchorus olitorius and kelp are preferred. As the parts of the plant, for example, leaves, bark, stems, roots, etc. can be listed, among which leaves and bark are preferred.

The repose angle of the plant powder is preferably not less than 47 degrees and not more than 57 degrees. The reason is that in order to obtain the desired high coagulation characteristics and the effect of reducing the water content of the sludge, the particle size of the plant powder used as the raw material needs to be within an appropriate range (53 μm to 710 μm). However, if the plant with a relatively low density is reduced to a fine powder of this size, its fluidity will be greatly deteriorated, and the repose angle, which is one of the indicators of fluidity, will show a value of 47 to 57 degrees. Furthermore, if the above-mentioned particle size is further reduced, the repose angle exceeds 57 degrees and shows a larger value, but if the above-mentioned particle size is reduced to this extent, it will have an adverse effect on the performance of the drainage treatment agent containing it, so it is not preferred.

Regarding the content ratio (mass ratio) of plant powder and flocculant polymer in the above-mentioned wastewater treatment agent, the optimal value will change according to the type or concentration of environmental load components in the wastewater to be treated, and the type or concentration of coexisting substances that interfere, so the product with the best blending ratio is selected for each type of wastewater. Among them, the content ratio (mass ratio) of plant powder and flocculant polymer in wastewater treatment agents used to treat various heavy metals or fluorides is preferably 10%:90% to 30%:70%.

The above-mentioned plant powder preferably contains a certain amount of cationic components.

- Flocculant polymer- As the above-mentioned flocculant polymer, as long as it has a certain amount of anionic components and is completely water-soluble, it can be appropriately selected according to the purpose, for example, acrylic acid acrylamide copolymer (commonly known as PAM) is preferred. As the above-mentioned PAM, for example, there can be listed those having carboxylic acid salts to have anionic properties. As the above-mentioned PAM, commercial products can be used, and as the above-mentioned commercial products, for example, there can be listed Flopan AN913 (PAM with carboxylic acid salts on the side chains) (both manufactured by SNF Co., Ltd.) and the like.

Most of the commercially available flocculant polymers have good fluidity and their repose angle is almost below 38 degrees. The reason is that the manufacturers of flocculant polymers control their physical properties (bulk density or particle size) in order to ensure good fluidity. Therefore, most of the commercially available flocculant polymers that can be used as raw materials for the present invention have a repose angle of 37 degrees.

The bulk density of the drainage treatment agent is not particularly limited and can be appropriately selected according to the purpose. It is preferably 0.55 g/mL or more, and more preferably 0.60 g/mL or more. If the bulk density is 0.55 g/mL or more, the equipment used to dissolve the flocculant polymer can be used without modification, thereby saving the initial cost required to introduce the drainage treatment agent of the present invention. The bulk density of the drainage treatment agent can be measured using a powder tester PT-X (manufactured by Hosokawa Micron Co., Ltd.) as an industry standard. 100 cc of the drainage treatment agent is slowly added to a 100 cc stainless steel cup, and the bulk density of the drainage treatment agent at this time is measured.

In order to ensure high fluidity and solubility during use, the particle size of the above-mentioned drainage treatment agent needs to be controlled to a particle size of 150 μm or more and 1 mm or less. As for its particle size distribution, it is more preferably 250 μm or more and 850 μm or less. The particle size distribution of the above-mentioned drainage treatment agent is preferably measured dryly, for example, using Morphologi G3 (manufactured by Malvern Instruments) or the like.

(Manufacturing method of drainage treatment agent) The manufacturing method of the drainage treatment agent of the present invention includes a mixing step and an extrusion molding step, and preferably includes a primary drying step, a granulation step, a secondary drying step, and further includes other steps as needed. The drainage treatment agent of the present invention can be suitably manufactured by the manufacturing method of the drainage treatment agent of the present invention.

<Mixture preparation step> The mixture preparation step is a step of preparing a mixture by using a pressure kneader to knead the plant powder and the flocculant polymer while adding water. In the mixture preparation step, by using a pressure kneader, a higher shear force can be applied to the mixture, as a result, the plant powder and the flocculant polymer, which are heterogeneous materials, are combined with each other and integrated. Specifically, the water added to the kneading equipment will be preferentially absorbed by the flocculant polymer and not absorbed by the plant powder. However, due to the higher shear force of the pressure kneading machine, the water that is forcibly squeezed out of the flocculant polymer will be absorbed by the plant powder, resulting in a state in which both the plant powder and the flocculant polymer are partially dissolved in water. In this way, the physical bonding (fibers are entangled with each other) and the electrochemical bonding of the plant powder and the flocculant polymer are simultaneously generated and integrated. Furthermore, in the present invention, in order to obtain a higher shear force, a pressure kneading machine with two blades was used for research and the desired result was found. On the other hand, when a kneading machine is changed to a blade specification that increases the shear force, such as 3 blades, it is possible to obtain the same high shear force even without applying pressure. It can be easily inferred that the same result can be obtained by using such a kneading machine with an increased number of blades.

There is no particular restriction on the number of blades of the above-mentioned pressurized kneader, and it can be appropriately selected according to the purpose. However, if the number of blades is increased and the shear force is excessively increased, there is a risk of over-mixing and damaging the quality of the finished product. Therefore, considering its balance, 2 blades are preferred. There is no particular restriction on the pressurized cover of the above-mentioned pressurized kneader, and it can be appropriately selected according to the purpose. For example, it can be listed that can use a pressurized cylinder for pressurization. By providing the pressurized kneader with a pressurized cover, shear force can be uniformly applied to the kneaded material, and the scattering of dust generated when adding water for kneading can be suppressed. The pressure of the above-mentioned pressurized cover is preferably 0.6 MPa or more.

The temperature during the kneading with water is preferably 15°C to 40°C in order to suppress thermal degradation or changes in mechanical properties of the raw materials to be kneaded.

Regarding the amount of water added during the water-adding and kneading, the amount of water added is a factor that affects not only the kneading step but also the subsequent extrusion molding step or drying step, and therefore needs to be managed to an optimal value. Specifically, it is preferably about 1 times the total mass of the plant powder and the flocculant polymer mixed.

The rotation speed of the blades during the water addition and kneading process is in the range of 10 rpm to 40 rpm. Although a higher shear force is required, if the shear force is too high, the flocculant polymer will deteriorate and the quality of the finished product will be damaged. Therefore, the blade rotation speed or kneading time needs to be managed to the optimal value.

<Extrusion molding step> The extrusion molding step is a step of obtaining a molded product by extruding the kneaded product using a twin-screw molding machine. In the extrusion molding step, the kneaded product is pressurized and extruded by the twin-screw molding machine, which can promote the densification of the kneaded product and increase the true specific gravity of the molded product. This effect can increase the aerated bulk density of the finished product, thereby achieving the above-mentioned drainage treatment agent with higher fluidity. Furthermore, 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 efficiency of the following drying step (primary drying step and secondary drying step) and granulation step is improved, which can improve the productivity of the above-mentioned drainage treatment agent.

The materials suitable for the above twin-screw extruder will vary according to the blade shape of the screw, so it is necessary to pay attention. In addition, the degree of densification or productivity will vary greatly according to the hole shape (hole diameter, number of holes, or hole configuration) of the die for extruding the kneaded material, so it is necessary to optimize it according to the physical property value of the input kneaded material. In the present invention, a twin-screw extruder designed for manufacturing tire rubber pellets is used, and the hole diameter of the die is φ3.5 mm.

The temperature of 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 higher and 36 rpm or lower. If the rotation speed is above 40 rpm, there is a risk that the kneading in the twin screw is accelerated, resulting in excessive kneading, thereby deteriorating the quality of the finished product.

<Primary drying step> The primary drying step is a step of drying the molded product to a moisture content of 15% to 25% to obtain a primary dried product. By drying the molded product to a moisture content of 15% to 25%, the molded product has softness, thereby suppressing physical damage to the primary dried product in the following granulation step, and suppressing the generation of fine powder in the granulation step. As the primary drying step, it is necessary to prevent the molded product (granules) from bonding to each other to form a huge block during drying, and to dry the molded product to a moisture content of 15% to 25%. Therefore, in the present invention, a vibrating fluidized bed dryer is used to perform drying in a continuous processing manner. Regarding the drying conditions at this time, the treatment is carried out under the conditions of hot air temperature below 80℃ and drying time (retention time in the dryer) of 5 minutes to 10 minutes.

<Particle-forming step> The above-mentioned particle-forming step is a step of obtaining particles by crushing the above-mentioned primary dried material, and the yield of fine powder with a particle size of less than 250 μm is preferably less than 18 mass% relative to all particles. As the above-mentioned particle-forming step, it is necessary to crush particles of several mm in size into powder of 250 μm to 850 μm by one treatment. In addition, the suitable crushing method varies depending on the hardness and constituent material of the particles, so it is necessary to select a crusher that takes into account the necessary processing capacity and processability. In the present invention, a multi-blade shredder is combined with an air conveying system to continuously supply a certain amount of particles to the crusher for crushing.

<Secondary drying step> The secondary drying step is a step of drying the crushed particles to a moisture content of 6% or less. As the secondary drying step, it is necessary to frequently measure and monitor the temperature of the product in the dryer, and to control the hot air temperature and drying time so that the temperature of the product does not rise to above 80°C, and to perform the drying process. Therefore, in the present invention, a fluidized bed dryer is combined with an air delivery system, and hot air of about 100°C is delivered to 4 kg to 5 kg of the product each time, and the drying process is performed in such a way that the product temperature becomes below 80°C. The drying time at this time is 10 minutes to 15 minutes.

<Other steps> As the above-mentioned other steps, for example, a grading step can be listed. In the above-mentioned grading step, it is preferable to use a grading machine such as a vibration screen, a drum screen, etc. to grade the particles so that the dried particles have a good particle size of 250 μm or more and 850 μm or less.

(Usage method of drainage treatment agent) As a method of using the drainage treatment agent, the drainage treatment agent of the present invention is dissolved in water at a specific concentration to obtain an aqueous solution, which is supplied to drainage after adding an inorganic flocculant, thereby causing the fine particles of inorganic waste in the drainage to condense and precipitate and be removed from the drainage. As the inorganic waste, for example, inorganic waste containing at least one of nickel, fluorine, iron, copper, zinc, chromium, arsenic, cadmium, tin, and lead can be listed.

The water purification method of the present invention is specifically described. The inorganic waste materials (nickel, chromium, copper, zinc, fluorine, etc.) to be removed are usually dissolved in the form of ions in the wastewater. Therefore, first, a neutralizer or coagulant corresponding to each component is used to solidify the ions to form micro-flocs. Then, an inorganic flocculant such as PAC (polyaluminum chloride) is added to improve the surface potential balance of the micro-flocs to promote coagulation and increase the size. However, if only the above-mentioned inorganic flocculant is added, the flocs cannot be increased to a size that can be condensed and precipitated in a short time. Therefore, an appropriate amount of the wastewater treatment agent solution of the present invention, which is made into an aqueous solution of 0.1 mass% to 0.2 mass%, is added thereto. As a result, the micro-floc crystals grow to a size that can condense and precipitate in a short time. By separating and recovering the precipitate, the useless substances in the drainage are removed and the purified drainage is obtained. When performing the above-mentioned drainage treatment, the amount of the reagents (neutralizer, inorganic flocculant, drainage treatment agent of the present invention) used varies greatly depending on the concentration of each component in the drainage, the initial pH value, or the drainage volume, and the input amount needs to be adjusted according to the drainage. However, the increase in the amount of the above-mentioned reagents directly leads to an increase in the cost of drainage treatment, so the less the amount used, the better. [Example]

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

<Preparation Example 1 of Plant Powder> The whole long capsule jute is dried by sun drying or the like until the moisture content becomes less than 10%. Then, the dried plant is crushed by a chopper or the like until the particle size distribution becomes 50 μm to 710 μm, thereby obtaining plant powder.

(Example 1) -Water-adding and kneading step- After mixing 20% by mass of the above-mentioned plant powder with 80% by mass of a flocculant polymer (polyacrylamide, Flopan AN 926 manufactured by SNF Co., Ltd.) to obtain a mixture, 95% by mass of water is added to the obtained mixture, and water-adding and kneading is performed for 3 minutes using a pressure kneader to obtain a kneaded product. -Extrusion molding step- The obtained kneaded product is extruded and molded using a twin-screw extruder designed for the manufacture of tire rubber pellets, and the molded product extruded from a die hole with a size (φ) of 3.5 mm is cut into a length (L) of less than 5 mm by a rotary knife. -Primary drying step- The obtained molded product was managed in a vibration flow dryer manufactured by DALTON so that the molded product (granular) would not be combined with each other to form a large block during drying, and the drying was continuously performed to obtain a primary dried product. The moisture content of the obtained primary dried product was measured using an infrared moisture meter and the result was 15% to 25%. -Particleization step- The obtained primary dried product was crushed using a multi-blade shredder manufactured by HORAI to obtain granules. The yield of fine powder with a particle size of less than 250 μm when crushed by the shredder was 10% to 18% by mass relative to all particles. -Secondary drying step- In order to eliminate the adhesion and bonding between particles, the obtained particles are secondary dried using a fluidized bed dryer manufactured by DALTON. At this time, in order to prevent the product temperature from rising above 80°C, a temperature sensor is inserted into the dryer to measure the product temperature, and the process is carried out in batches. The moisture content of the secondary dried product obtained is measured using an infrared moisture meter, and the result is less than 6%. -Grading step- The particles with a particle size larger than 850 μm in the obtained drainage treatment agent are removed by a sieve with a nominal mesh size of 850 μm (mesh number No. 20), and the particles with a particle size smaller than 250 μm are removed by a sieve with a nominal mesh size of 250 μm (mesh number No. 60), thereby obtaining a drainage treatment agent with a particle size of more than 250 μm and less than 850 μm.

(Comparative Example 1) 30% by mass of the above plant powder and 70% by mass of a flocculant polymer (polyacrylamide, Flopan AN 926 manufactured by SNF Co., Ltd.) were placed in a plastic bag and then manually shaken for more than 5 minutes to mix, thereby obtaining a drainage treatment agent.

(Comparative Example 2) In Comparative Example 1, except that the content of plant powder was changed to 20 mass %, and the content of flocculant polymer was changed to 80 mass %, a wastewater treatment agent was obtained in the same manner as in Comparative Example 1.

(Comparative Example 3) In Comparative Example 1, except that the content of plant powder was changed to 10 mass %, and the content of flocculant polymer was changed to 90 mass %, a wastewater treatment agent was obtained in the same manner as in Comparative Example 1.

(Comparative Example 4) First, the content of plant powder is set to 20% by mass, and the content of flocculant polymer is set to 80% by mass. The water-adding and kneading step is performed by a planetary mixer (the amount of water added is about 230% relative to the weight of the raw material mixture, and the kneading time is about 10 minutes). Then, the kneaded material is torn into blocks of appropriate size (about φ30 to 50 mm) by manual operation, placed on a rack covered with a mesh, and dried together with the rack by a hot air dryer (dried at 80°C for more than 20 hours). The block-shaped dried material with a moisture content of less than 6% is crushed in two stages by a chopper to make it into a powder. Finally, the wastewater is classified by a vibrating screen or the like so that its particle size distribution becomes 250 μm to 850 μm, thereby obtaining a wastewater treatment agent.

(Comparative Example 5) First, the content of plant powder is set to 20% by mass, and the content of flocculant polymer is set to 80% by mass. A water-adding and kneading step is performed by a planetary mixer (the amount of water added is about 230% relative to the weight of the raw material mixture, and the kneading time is about 10 minutes). Then, the mixture is placed in a rectangular box, covered with a pressure cover, and pressurized for about 1 minute under a pressure of 0.5 MPa to obtain a block-shaped molded body. Furthermore, the molded body is cut into a size of about 15 cm square, and the cut blocks are formed into sheets with a thickness of less than 7 mm one by one using a stretching machine. The obtained molded product is placed on a rack covered with a mesh and dried together with the rack using a hot air dryer (dried at 80°C for more than 20 hours). The block-shaped dried product with a moisture content of less than 6% is crushed in two stages using a chopper to make it powdery. Finally, it is classified using a vibrating screen or the like so that the particle size distribution becomes 250 μm to 850 μm to obtain a drainage treatment agent.

First, the repose angles and bulk densities of the raw material elements used in this study were measured. Then, the repose angles and bulk densities of the drainage treatment agents of Example 1 and Comparative Examples 1 to 5 were measured. In addition, the manufacturing lead time and manufacturing yield of the drainage treatment agents of Example 1 and Comparative Examples 4 to 5 were evaluated. The results are shown in Table 1.

[Stationary Angle] The stationary angle is measured using a powder tester PT-X (manufactured by Hosokawa Micron). Using the company's standard measurement conditions, the sample to be measured is dropped from a funnel onto a circular support platform, and the angle between the slope and the horizontal plane when a mountain-shaped layer is formed is measured.

[Bulk density] The loose filling bulk density was measured using a powder tester PT-X (manufactured by Hosokawa Micron). Using the company's standard measurement conditions, the drainage treatment agent was slowly added little by little from above into a 100cc stainless steel cup and intentionally overflowed. The weight of the cup contents after removing the overflow from the upper surface of the cup was measured to determine the loose filling bulk density of the drainage treatment agent at that time.

(Evaluation) <Supply stability> Each wastewater treatment agent is added to a hopper at an angle of 60 degrees and automatically supplied to the dissolution tank. At this time, whether stable supply can be achieved is evaluated according to the following criteria. -Evaluation criteria- A: No bridge or rat hole occurs, and stable supply can be continued. B: Although bridge or rat hole occurs, the bridge or rat hole disappears by vibrating the hopper, and the supply can be continued. C: Bridge or rat hole occurs, and even if the hopper is vibrated, the bridge or rat hole is not eliminated, and stable supply cannot be achieved.

<Manufacturing lead time> The manufacturing lead time (manufacturing L/T) is the time from the time the above-mentioned plant powder and the above-mentioned flocculant polymer are weighed to the time the wastewater treatment agent is obtained.

＜Manufacturing yield＞ Manufacturing yield is measured by the finished product quantity (weight)/total raw material input quantity (weight).

[Table 1] Blending conditions Physical properties Reviews Plant powder (mass %) Flocculant polymer (mass %) Still angle (degrees) Sparse filling volume density (g/ML) Supply stability Manufacturing L/T (minutes) Manufacturing yield (%) Fine powder production rate (%) Plant powder element 100 - 52.3 0.10～0.20 C - - - Flocculant polymer monomer - 100 37.1 0.62～0.78 A - - - Comparative example 1 30 70 44.7 - C - - - Comparative example 2 20 80 43.1 0.44～0.50 C - - - Comparative example 3 10 90 41.2 - C - - - Comparative example 4 20 80 40.8 0.48～0.54 B 2880 48 34～42 Comparative example 5 20 80 39.8 0.56～0.62 B 2160 58 34～42 Embodiment 1 20 80 35.9 0.63～0.70 A 162 81 10～18

without

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Claims (6)

A drainage treatment agent, characterized in that it comprises particles containing plant powder and flocculant polymer, the repose angle is less than 38 degrees, and the repose angle of the plant powder is 47 degrees to 57 degrees. For wastewater treatment agents in Request Item 1, their bulk density shall be 0.55 g/mL or above. If the drainage treatment agent in item 1 or 2 is requested, the repose angle shall be less than 37 degrees. The wastewater treatment agent of claim 1 or 2, 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 of claim 1 or 2, wherein the plant powder contains a cationic component and the flocculant polymer contains an anionic component. A method for producing a drainage treatment agent, characterized in that it comprises: a mixed material preparation step, in which a plant powder and a flocculant polymer are mixed with water using a pressure kneader to prepare a mixed material; an extrusion molding step, in which the mixed material is extruded and molded using a twin-screw molding machine to obtain a molded product; a primary drying step, in which the molded product is dried in such a way that the moisture content becomes 15% to 25% to obtain a primary dried product; a granulation step, in which the primary dried product is crushed to obtain particles; and a secondary drying step, in which the particles are dried, and in the granulation step, the generation rate of fine powder with a particle size of less than 250 μm is less than 18% by mass relative to all particles.