CN113666470B

CN113666470B - Wastewater treatment agent and method for producing wastewater treatment agent

Info

Publication number: CN113666470B
Application number: CN202110516198.9A
Authority: CN
Inventors: 松永融; 伊东雅彦; 广芝泰祐
Original assignee: Dexerials Corp
Current assignee: Dexerials Corp
Priority date: 2020-05-14
Filing date: 2021-05-12
Publication date: 2024-04-23
Anticipated expiration: 2041-05-12
Also published as: CN113666470A; JP2021178291A; TW202202456A

Abstract

The purpose of the present invention is to provide a wastewater treatment agent which contains a large amount of components having poor fluidity such as celluloses, but which has excellent fluidity and can prevent bridging and mouseholes from occurring in a hopper in an automatic supply system, and a method for producing the wastewater treatment agent. A wastewater treatment agent comprising particles containing cellulose acetate and a coagulant polymer, the angle of repose being 38 degrees or less.

Description

Wastewater treatment agent and method for producing wastewater treatment agent

Technical Field

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

Background

In recent years, in the production of various products in factories, a large amount of wastewater containing environmental load substances such as metal ions or fluorine ions as inorganic ions is generated, and a wastewater treatment agent is used for purifying the wastewater.

Since wastewater treatment is performed during the passage through a plurality of tanks, the chemical (wastewater treatment agent) supplied to each tank is usually supplied in a liquid form, and the chemical such as a solid powder of a coagulant (flocculant) polymer is prepared into a syrup-like aqueous solution using a dedicated dissolving device and then supplied to the treatment tank. In the case where the amount of wastewater to be treated is large or in the case where treatment is performed by automatic operation, there are many cases where a device in which a system for automatically supplying a chemical is attached to the dissolution apparatus is used. In this case, in order to obtain a solution having a certain concentration, an apparatus having a mechanism for quantitatively supplying a chemical as a solid powder by utilizing the self weight and fluidity of the chemical is widely used. In the case where the amount of wastewater is small or the fluctuation of wastewater to be treated is large, the condition may be manually changed to dissolve the wastewater, but the automatic supply system described above is often employed because of an increase in the number of steps and the like and an increase in the site load.

Among them, the lower the water content of the dehydrated sludge produced after the dehydration treatment, the smaller the waste treatment amount, and the treatment cost can be reduced, and therefore, it is desired to highly dehydrate the sludge.

For this reason, for example, an inorganic sludge dewatering agent for press filtration has been proposed which can reduce the water content of an inorganic sludge cake by using alkylene oxide (for example, see patent document 1). In addition, a sludge dewatering auxiliary agent comprising viscose rayon having a fiber-like material with a water content of 30 to 80% by weight is proposed. In addition, a method of dewatering sludge has been proposed in which a dewatering auxiliary agent and a polymer flocculant are added and mixed to organic sludge, and then mechanical dewatering is performed (for example, see patent document 2).

Prior art literature

Patent literature

Patent document 1: japanese patent No. 6123158;

patent document 2: japanese patent publication No. 4817431.

Disclosure of Invention

Problems to be solved by the invention

The present invention solves the above-described problems and achieves the following objects. That is, the present invention aims to: provided are a wastewater treatment agent which contains a large amount of components having poor fluidity such as celluloses, but which has excellent fluidity and can prevent bridging or rat holes from occurring in a hopper in an automatic supply system, and a method for producing the wastewater treatment agent.

Means for solving the problems

In the prior art, a wastewater treatment agent which combines cellulose and coagulant polymers excellent in waterproof property and has both the effect of reducing the water content of sludge and high coagulation property has been proposed, but such a wastewater treatment agent contains a considerable amount of cellulose which is poor in fluidity and poor in affinity with water as one of the raw materials, and therefore it is difficult to combine/integrate with the coagulant polymers to produce a granular state good in fluidity, and there is a problem that fluidity of a granulated product or a mixture thereof is easily deteriorated.

Means for solving the above problems are as follows. That is to say,

<1> A wastewater treatment agent, characterized in that:

comprising particles comprising cellulose acetate (Cellulose acetate, cellulose acetate or cellulose acetate) and a coagulant polymer,

The angle of repose is 38 degrees or less.

<2> The wastewater treatment agent according to the above <1>, wherein the bulk density of the wastewater treatment agent is 0.46g/mL or more.

<3> The wastewater treatment agent according to any one of the above <1> to <2>, wherein the repose angle of the wastewater treatment agent is 37 degrees or less.

<4> The wastewater treatment agent according to any one of the above <1> to <3>, wherein the mass ratio of the cellulose acetate to the coagulant polymer (cellulose acetate: coagulant polymer) is 40%:60% -60%: 40%.

<5> A method for producing a wastewater treatment agent, comprising the steps of:

A kneaded material preparation step of kneading cellulose acetate and a coagulant polymer with water using a pressure kneader to prepare a kneaded material; and

And an extrusion molding step of extrusion-molding the kneaded product using a biaxial screw molding machine to obtain a molded product.

<6> The method for producing a wastewater treatment agent according to <5> above, comprising the steps of:

a primary drying step of drying the molded product to a water content of 14 to 22% to obtain a primary dried product;

granulating, namely crushing the primary dried product to obtain granules; and

And a secondary drying step of drying the granules.

<7> The method for producing a wastewater treatment agent according to <6>, wherein in the granulating step, the generation rate of fine powder having a particle diameter of less than 250 μm is 19 mass% or less relative to the total particles.

Effects of the invention

According to the present invention, the above-described problems can be solved, and the above-described object can be achieved by providing a wastewater treatment agent which contains a large amount of components having poor fluidity such as cellulose, but is excellent in fluidity, and which can prevent bridging or mousehole from occurring in a hopper in an automatic supply system, and a method for producing the wastewater treatment agent.

Detailed Description

(Wastewater treatment agent)

The wastewater treatment agent of the present invention contains particles containing cellulose acetate and a coagulant polymer, and if necessary, other components.

The angle of repose of the wastewater treatment agent is 38 degrees or less (less than 38.5 degrees when the 1 st position is considered), preferably 37 degrees or less. When the angle of repose is 38 degrees or less, fluidity of the wastewater treatment agent is improved, and bridging or mousehole in a hopper in an automatic supply system can be prevented.

The angle of repose of the wastewater treatment agent can be measured, for example, by using a powder tester PT-X (manufactured by Hosokawa Micron corporation) or the like, and the wastewater treatment agent to be measured is dropped onto a circular support table via a funnel, and the angle between the inclined surface and the horizontal surface when forming a layer on a mountain (angle bar) is measured.

The wastewater treatment agent of the present invention is produced by the method for producing a wastewater treatment agent of the present invention described below, and is formed as particles in which the cellulose acetate and the coagulant polymer are integrated, and the angle of repose is 38 degrees or less.

< Particles >

The particles contain the cellulose acetate and the coagulant polymer, and if necessary, other components.

In the above-mentioned granules, the above-mentioned cellulose acetate and the above-mentioned coagulant polymer are integrally formed. If the cellulose acetate and the coagulant polymer are integrated, the fluidity of the wastewater treatment agent is improved, and bridging or rat holes in a hopper in an 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 may be appropriately selected according to the purpose, and examples thereof include: approximately spherical, needle-like, non-spherical, etc. Among these, from the viewpoint of having high fluidity, an approximately spherical shape is also preferable.

Cellulose acetate-

The cellulose acetate is a cellulose ester obtained by esterifying a part of hydrogen in cellulose with Cheng Yi acid groups.

The product form of commercially available cellulose acetate is mainly film-like or fibrous, and the product form of powder is small. However, in order to produce the wastewater treatment agent of the present invention, it is necessary that the wastewater treatment agent is in the form of powder and has a particle size of 1.5mm or less (desirably 0.355mm or less). In addition, since the true specific gravity of the material itself is light, the angle of repose as the obtainable 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 is, the more the effect of reducing the water content of the sludge can be improved.

The weight average molecular weight of the cellulose acetate is, for example, a value obtained by converting a measurement value by gel permeation chromatography into a molecular weight of a standard polymethyl methacrylate.

The above cellulose acetate as one of the starting materials is preferably in the form of powder or granule.

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, from the viewpoint of constraints on the production process, and most preferably 355 μm or less from the viewpoint of product characteristics. When the particle size is 1,500 μm or less, the water content of the sludge can be reduced.

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

Coagulant polymer

The coagulant polymer may be any polymer that exhibits an effect of removing inorganic waste in wastewater and is completely water-soluble, and may be appropriately selected according to the purpose, and for example, an acrylic acid/acrylamide copolymer (generally, PAM) is preferable.

Examples of PAM include: PAM having carboxylate for anionic property, and the like.

As the PAM, commercially available products can be used, and examples of the commercially available products include: flopan AN913 (PAM having carboxylate in the side chain) (manufactured by SNF, inc.) and the like.

Most of the coagulant polymers on the market have good fluidity, and the repose angle is mostly 40 degrees or less. This is because manufacturers of coagulant polymers control their physical properties (bulk density or particle size) in order to ensure good flowability. Therefore, many commercially available coagulant polymers used in the raw materials of the present invention are available, and the coagulant polymer used for the study has an angle of repose of 37 degrees.

The content of the coagulant polymer is not particularly limited and may be appropriately selected according to the purpose, and 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 coagulant polymer (cellulose acetate: coagulant polymer) is preferably 40%:60% -60%: 40%, more preferably 50%:50%. If the mass ratio is 40%:60% -60%: 40% can have both high cohesiveness and water content reducing effect.

Other ingredients-

The other components are not particularly limited and may be appropriately selected according to the purpose, and examples thereof include: plant powder, and the like.

The plant powder is obtained by pulverizing a plant.

The plant is not particularly limited as long as it is a plant capable of coagulating and separating inorganic waste (nickel, copper, fluorine, etc.) in wastewater, and may be appropriately selected according to the purpose, and examples thereof include: radix seu herba Heterophyllae (Corchorus olitorius), egyptian King cabbage (molokheiya), herba Orostachyos, herba Apii Graveolentis, herba Equiseti Arvinsis, herba Spinaciae, etc. Among these, jute and Egyptian King cabbage are preferable.

Examples of the plant parts include: leaves, bark, stems, roots, etc., among which leaves and bark are preferred.

The angle of repose of the plant powder is not particularly limited, and may be appropriately selected according to the purpose, and 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 according to the purpose, and 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 coagulation of the micro-flocculates is promoted by the components contained in the plant powder, and the coagulation and precipitation are achieved in a short time. On the other hand, if the content of the plant powder is too high, the content of the coagulant polymer component required for the coagulation is reduced, and the blending balance of the components is deteriorated, so that the content is preferably 10 mass% or less.

The particle size of the wastewater treatment agent needs to be controlled to a particle size of 150 μm or more and 1mm or less to ensure high fluidity and solubility in use. The particle size distribution is more preferably 250 μm or more and 850 μm or less.

The particle size distribution of the wastewater treatment agent is preferably measured in principle in a dry manner, and can be measured, for example, using Morphologic G3 (manufactured by Malvern Co., ltd.).

The bulk density of the wastewater treatment agent is not particularly limited, and may be appropriately selected according to the purpose, but is preferably 0.46g/mL or more, more preferably 0.51g/mL or more. When the bulk density is 0.46g/mL or more, the facility for dissolving the coagulant polymer can be used without modification, and therefore the initial cost required for introducing the wastewater treatment agent of the present invention can be saved.

The bulk density of the wastewater treatment agent was measured by using a powder tester PT-X (manufactured by Hosokawa Micron Co., ltd.) as an industry standard, and 100cc of the wastewater treatment agent was gently added to a 100cc stainless steel cup, and the bulk density of the wastewater treatment agent at this time was measured.

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, cellulose acetate powder which is not integrally formed with the coagulant polymer is small, and a wastewater treatment agent with small deviation in repose angle and bulk density can be realized.

Here, the CA separation rate can be obtained as follows.

[ CA separation Rate ]

7G of a wastewater treatment agent as a measurement sample was poured into 350g of acetone, and dissolved in an ultrasonic washer at 28kHz, 30 to 40℃for 10 minutes to obtain a solution. Next, the obtained solution was filtered using a qualitative filter paper (retention particle diameter: 6 μm) to obtain a residue. The resulting residue was dried at 80 ℃ for more than 30 minutes to completely evaporate/remove acetone in the residue, after which the mass X (g) of the dried residue was measured. The measurement method is a measurement method using the following 2-point property: while cellulose acetate is soluble in acetone, coagulant polymers or other ingredients are insoluble in acetone; and cellulose acetate separated from other components such as coagulant polymer is preferentially dissolved in acetone. Thus, the CA separation rate can be obtained from the following calculation formula.

CA separation rate (%) = (7-X)/7×100

(Process for producing 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, and preferably includes a primary drying step, a granulation step, a secondary drying step, and other steps as necessary. The method for producing a wastewater treatment agent according to the present invention can be suitably used for producing a wastewater treatment agent according to the present invention.

< Procedure for preparing kneaded Material >

The kneaded material preparation step is a step of preparing a kneaded material by kneading the cellulose acetate powder and the coagulant polymer with water using a pressure kneader. In the kneaded material preparation step, a high shear force can be applied to the kneaded material by using a pressure kneader, and as a result, it is possible to bond and integrate heterogeneous materials having low affinity such as the cellulose acetate powder and the coagulant polymer to each other.

Specifically, the water fed to the kneading apparatus is preferentially absorbed only by the coagulant polymer, and is not absorbed at all by the water-repellent cellulose acetate powder. Here, the high shear force of the pressure kneader forcibly and uniformly permeates the water absorbed in the coagulant polymer into the whole coagulant polymer, thereby forming the entire coagulant polymer into a semi-dissolved state. By forming the coagulant polymer as a solid powder into a semi-dissolved state, the coagulant polymer is formed into a state such as a high-viscosity adhesive, and as if a state in which cellulose acetate powder is dispersed in a high-viscosity liquid such as the coagulant polymer can be produced. Further kneading forcibly bonds the water-repellent and water-insoluble cellulose acetate powder to the coagulant polymer. Thus, cellulose acetate which originally lacks affinity is strongly bonded to and integrated with the coagulant polymer.

In the present invention, a pressure kneader having 2 blades was used to obtain a high shear force, and desired results were observed. On the other hand, for example, in the case of changing to a kneader of a blade type such as 3 blades or the like, which improves the shearing force, it is possible to obtain a shearing force as high as possible even without pressurizing, and if such a kneader with an increased number of blades is used, it can be easily estimated that the same result is obtained.

The number of blades of the pressure kneader is not particularly limited, and may be appropriately selected according to the purpose, and if the number of blades is increased to excessively increase the shearing force, there is a risk that the quality of the product is impaired due to the formation of a kneaded state, and therefore, 2 blades are preferable in consideration of the balance.

The pressure cap of the pressure kneader is not particularly limited and may be appropriately selected according to the purpose, and examples thereof include: a pressurizing cover or the like that pressurizes using a pressurizing air cylinder (AIR CYLINDER, cylinder) may be used. By providing the pressure kneader with a pressure cap, a shearing force can be uniformly applied to the kneaded material, and scattering of dust generated during water-added kneading can be suppressed. The pressure of the pressurizing cover is preferably 0.6MPa or more.

The temperature during the water addition kneading is preferably 15 to 40 ℃.

The amount of water added in the water-added kneading 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 controlled to an optimum value. Specifically, the amount of the coagulant polymer is preferably about 72% by mass based on the total mass obtained by mixing the cellulose acetate powder, the coagulant polymer, and the raw materials thereof.

The rotation speed of the blade during the water addition kneading is in the range of 10rpm to 40 rpm. The time for kneading with water is preferably, for example, 3 minutes to 8 minutes. Although high shear force and kneading based on the shear force are necessary, if the shear force is too high or the kneading time is too long, deterioration of the coagulant polymer occurs to deteriorate the quality of the product, and therefore the rotation speed of the blade or the kneading time needs to be controlled to an optimum value.

< Extrusion molding Process >

The extrusion molding step is a step of extrusion molding the kneaded product using a biaxial screw molding machine to obtain a molded product. In the extrusion molding step, the kneaded material is extrusion molded while being pressurized by a twin-screw extruder, whereby densification of the kneaded material can be promoted and the true specific gravity of the molded material can be improved. According to this effect, the bulk density of the finished product can be increased, and the wastewater treatment agent having high fluidity can be realized. Further, by continuously cutting the molded product into pellets immediately after extrusion, densification and granulation of the kneaded product can be performed simultaneously, and the efficiency of the drying step (primary drying step and secondary drying step) and the granulating step described later can be improved, and the yield of the wastewater treatment agent can be improved.

The twin-screw molding machine is required to pay attention because the suitable materials thereof are changed according to the blade shape of the screw. In addition, since the degree of densification and the yield vary greatly depending on the shape of the holes (the pore diameter, the number of holes, and the arrangement of the holes) of the die for extruding the kneaded material, the degree of densification and the yield must be optimized depending on the physical property values of the kneaded material to be fed. In the present invention, a twin-screw extruder designed for producing particles for tire rubber is used, and the die has a pore diameter of

The temperature in the extrusion molding is preferably, for example, 15℃to 40 ℃.

The rotation speed of the biaxial screw in the extrusion molding is preferably, for example, 10rpm to 36 rpm. If the rotational speed is 40rpm or more, kneading in the biaxial screws is accelerated to cause excessive kneading, and the quality of the final product may be deteriorated.

< Primary drying Process >

The primary drying step is a step of drying the molded product to a water content of 14% to 22% to obtain a primary dried product. Since the molded article is dried so that the water content of the molded article is 14% to 22%, the molded article has flexibility, and physical damage to the primary dried article in the granulation step described later can be suppressed, and generation of fine powder in the granulation step can be suppressed.

As the primary drying step, it is necessary to dry the molded articles (pellets) so that they do not combine with each other to form a large block and so that the water content of the molded articles is 14% to 22%. In the present invention, therefore, drying is performed by continuous treatment using a vibratory flow dryer. The drying conditions in this case are that the treatment is carried out at a hot air temperature of 80 ℃ or lower for a drying time (residence time in the dryer) of 5 minutes to 10 minutes.

< Granulation Process >

The granulation step is a step of pulverizing the primary dried product to obtain granules, and preferably has a generation rate of fine powder having a particle size of less than 250 μm of 19 mass% or less relative to the total particles.

As the granulation step, it is necessary to pulverize particles of several mm in size into powder of 250 μm to 850 μm by 1 treatment. Further, since an appropriate pulverizing system varies depending on the hardness of the particles and the constituent materials, a pulverizer having both the necessary processing ability and workability needs to be selected.

In the present invention, a combination of a multi-blade chopper and air delivery system continuously supplies a certain amount of particles to a pulverizer for pulverization.

< Secondary drying Process >

The secondary drying step is a step of drying the pulverized particles to a water content of 6% or less.

As the secondary drying step, it is necessary to perform the drying process by constantly measuring and monitoring the temperature of the product in the dryer and controlling the hot air temperature and the drying time so that the product temperature does not rise to 80 ℃. Therefore, in the present invention, the fluidized bed dryer and the air conveying system are combined, and the product is dried while hot air at about 100 ℃ is fed to 4kg to 5kg of the product at a time so that the product temperature is 80 ℃ or lower. The drying time at this time is 10 minutes to 15 minutes.

< Other procedure >

Examples of the other steps include: a classification step, and the like.

In the classification step, the dried particles are preferably classified into a good product having a particle diameter of 250 μm or more and 850 μm or less by using a vibration sieve or a drum sieve or the like.

(Method of using wastewater treatment agent)

As a method for using the wastewater treatment agent, the wastewater treatment agent of the present invention is dissolved in water at a predetermined concentration, and the resulting aqueous solution is supplied to wastewater to which an inorganic coagulant is added, whereby fine particles of inorganic wastes in the wastewater are coagulated/precipitated and removed from the wastewater.

Examples of the inorganic waste include: inorganic waste containing at least one of nickel, fluorine, iron, copper, zinc, chromium, arsenic, cadmium, tin and lead, and the like.

The water purification method of the present invention will be specifically described.

Inorganic wastes (nickel, chromium, copper, zinc, fluorine, etc.) to be removed are usually dissolved in the wastewater in an ionic form. Therefore, the above-mentioned ions are first solidified by using a neutralizing agent, a coagulant, or the like corresponding to each component, to form a micro-flocculate. Next, an inorganic coagulant such as PAC (polyaluminum chloride) is added to improve the surface potential balance of the micro-flocculate and promote coagulation, thereby increasing the size. However, only by adding the above inorganic coagulant, the flocs cannot be increased to a size that can be coagulated/precipitated in a short time, and therefore, the wastewater treatment agent solution of the present invention in which an aqueous solution of 0.1 to 0.2 mass% has been formed is appropriately added thereto. As a result, the micro-flocculated particles grow to a size that can be coagulated and precipitated in a short time, and only the precipitate thereof is separated and recovered, whereby waste present in the wastewater is removed, thereby obtaining purified wastewater.

In the above-described wastewater treatment, the amount of the chemical agent (neutralizing agent, inorganic coagulant, wastewater treatment agent of the present invention) to be used varies greatly depending on the concentration of each component in wastewater, the initial pH value, the amount of wastewater, and the like, and the amount of the chemical agent to be added needs to be adjusted depending on the respective wastewater. However, increasing the amount of the above-mentioned chemical agent directly involves an increase in the cost of wastewater treatment, and therefore, the smaller the amount, the more preferable the amount.

Examples

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

Example 1

Mixing procedure with water

50 Mass% of cellulose acetate (median diameter: 200 μm to 330 μm, weight average molecular weight (Mw): 170,000, manufactured by China) and 50 mass% of coagulant polymer (polyacrylamide, flopan AN 926, manufactured by SNF, co., ltd.) were mixed to obtain a mixture, and then 72 mass% of water was added to the obtained mixture, and the mixture was kneaded with water using a 2-blade pressure kneader for 5 minutes to obtain a kneaded product.

Extrusion molding process

The obtained kneaded product was extrusion molded using a twin-screw extruder designed to manufacture particles for tire rubber, and the obtained kneaded product was extruded from the sizeThe molded article extruded through the die hole is cut into a length (L) of 5mm or less by a rotary knife.

Primary drying procedure

The obtained molded article was dried continuously while being managed so that the molded articles (pellets) were not bonded to each other to form a large block during drying using a vibration flow dryer manufactured by Dulton, to obtain a primary dried article. When the water content of the obtained primary dried product is measured by an infrared moisture meter, the water content thereof is 14% to 22%.

Granulation procedure-

The obtained primary dried product was pulverized using a multi-blade chopper manufactured by Horai company to obtain granules. The generation rate of fine powder having a particle size of less than 250 μm when pulverized by a chopper is 12 to 19 mass% relative to the total particles.

Secondary drying process

The resulting pellets were subjected to secondary drying using a fluidized bed dryer manufactured by Dulton company to eliminate the adhesion/bonding of the pellets to each other. At this time, a temperature sensor is inserted into the dryer so that the temperature of the product does not rise to 80 ℃ or higher, and batch processing is performed while measuring the temperature of the product. When the water content of the obtained secondary dried product was measured by an infrared hygrometer, the water content was 6% or less.

Grading procedure

The particles having a particle diameter of more than 850 μm in the obtained wastewater treatment agent were removed by a sieve having a nominal mesh of 850 μm (sieve number 20), and the particles having a particle diameter of less than 250 μm were removed by a sieve having a nominal mesh of 250 μm (sieve number 60), to obtain a wastewater treatment agent having a particle diameter of 250 μm or more and 850 μm or less.

Example 2

In example 1, a wastewater treatment agent was obtained in the same manner as in example 1 except that the content of cellulose acetate was changed from 50% by mass to 47.5% by mass, the content of coagulant polymer was changed from 50% by mass to 47.5% by mass, the entire portion of jute was dried to a water content of 10% or less by solar drying or the like, and then 5% by mass of plant powder obtained by pulverizing to a particle size distribution of 50 μm to 710 μm by a chopper or the like was added.

Comparative example 1

40 Mass% of cellulose acetate (median diameter: 200 μm to 330 μm, weight average molecular weight (Mw): 170,000, manufactured by China) and 60 mass% of coagulant polymer (polyacrylamide, flopan AN 926, manufactured by SNF, co., ltd.) were put into a plastic bag, and then manually shaken for 5 minutes or more, followed by mixing, to obtain a wastewater 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 cellulose acetate was changed to 50 mass% and the content of coagulant polymer was changed to 50 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 mass% and the content of coagulant polymer was changed to 40 mass%.

Comparative example 4

A water-adding and kneading step (the amount of water added is about 180% relative to the weight of the raw material mixture, and the kneading time is about 20 minutes) of 50% by mass of cellulose acetate (median diameter: 200 μm to 330 μm, weight average molecular weight (Mw): 170,000, manufactured by China) and 50% by mass of coagulant polymer (polyacrylamide, flopan AN 926, manufactured by SNF, co., ltd.) was performed using a planetary mixer. Next, the kneaded material was put into a rectangular box, and a press cover was placed thereon, and a pressure of about 0.5MPa was applied for 1 minute to perform press molding, thereby obtaining a block-shaped molded article. The molded article was cut into pieces having a square size of about 15cm, and the cut pieces were stretched one by a stretcher (manufactured by Xiao Song Kagaku Co., ltd., 45t press) to obtain a sheet-like molded article having a thickness of 6 mm.

The molded product was placed on a shelf on which a net was laid, and dried together with the shelf by a hot air dryer (80 ℃ C., 20 hours or more). The dried cake having a water content of 6% or less was pulverized into 2 stages by using a chopper to form a powder. Finally, classification is carried out by using a vibrating screen and the like to ensure that the granularity distribution is 250-850 mu m, thus obtaining the wastewater treatment agent.

[ Angle of repose ]

The angle of repose was measured using a PT-X powder tester (manufactured by HosokawaMicron Co.).

The sample to be measured was dropped onto a circular support via a funnel, and the angle between the inclined plane and the horizontal plane when forming a layer on a mountain (angle bar) was measured.

[ Bulk Density ]

100Cc of the wastewater treatment agent was gently charged into a 100cc stainless steel cup, and the density of the wastewater treatment agent at this time was measured by using a PT-X type powder tester (manufactured by Hosokawa Micron Co.).

[ Cellulose acetate separation Rate (CA separation Rate) ]

CA separation rate (%) = (7-X)/7×100

(Evaluation)

< Stability of supply >

Each wastewater treatment agent was charged into a hopper having an angle of 60 degrees, and when the wastewater treatment agent was automatically supplied to the dissolution tank, whether stable supply was possible was evaluated according to the following criteria.

Evaluation criterion-

A: stable supply can be continuously performed without generating bridge or rat hole;

b: although the bridge or the rat hole is generated, the bridge or the rat hole disappears by applying vibration to the hopper, and the feeding can be continuously performed;

C: the bridge or the mousehole is generated, and even if vibration is applied to the hopper, the bridge or the mousehole cannot be eliminated, and stable supply cannot be performed.

< Time required for production (Manufacturing lead time) >)

The time required for production (L/T production) was measured from the time point when the cellulose acetate and the coagulant polymer were weighed to the time when the wastewater treatment agent was obtained.

< Manufacturing yield (Manufacturing yield) >)

The production yield was measured as the finished product amount (weight)/total raw material input amount (weight).

TABLE 1

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Claims

1. The wastewater treatment agent is characterized in that:

Comprising particles comprising cellulose acetate and a coagulant polymer, wherein the cellulose acetate is in the form of a powder, has a particle size of 0.355mm or less, a median diameter of 200 [ mu ] m to 330 [ mu ] m, an angle of repose of 48 DEG to 58 DEG inclusive, a separation rate of 10% or less, and a weight average molecular weight of 100,000 or more,

The wastewater treatment agent has an angle of repose of 38 DEG or less, a particle diameter of 250-850 mu m, and a water content of 6% or less.

2. The wastewater treatment agent according to claim 1, wherein the bulk density of the wastewater treatment agent is 0.46g/mL or more.

3. The wastewater treatment agent according to claim 1, wherein an angle of repose of the wastewater treatment agent is 37 degrees or less.

4. The wastewater treatment agent according to any one of claims 1 to 3, wherein a mass ratio of the cellulose acetate to the coagulant polymer is cellulose acetate: the coagulant polymer was 40%:60% -60%: 40%.

5. The method for producing the wastewater treatment agent is characterized by comprising the following steps:

A kneaded material preparation step of kneading cellulose acetate powder, which is in the form of a powder having a particle size of 0.355mm or less, a median diameter of 200 to 330 μm, an angle of repose of 48 to 58 degrees, a separation rate of 10% or less, and a weight average molecular weight of 100,000 or more, and a coagulant polymer by adding water thereto using a pressure kneader, and preparing a kneaded material, wherein the cellulose acetate powder and a heterogeneous and weakly compatible material, which is the coagulant polymer which is in a semi-dissolved state by preferentially absorbing water fed to a kneading apparatus, are bonded to each other and integrated with each other by using the pressure kneader;

An extrusion molding step of extrusion-molding the kneaded material using a biaxial screw molding machine to obtain a molded article;

A granulation step of pulverizing the primary dried product to obtain granules, wherein the granulation step requires 1 treatment to pulverize granules having a size of several mm into a powder having a size of 250 μm to 850 μm; and

And a secondary drying step of drying the granules to a water content of 6% or less.

6. The method for producing a wastewater treatment agent according to claim 5, wherein in the granulating step, the generation rate of fine powder having a particle diameter of less than 250 μm is 19 mass% or less relative to the total particles.