Wastewater treatment method and wastewater treatment device

Abstract

To provide a drainage treatment method and a drainage treatment device which can efficiently treat drainage including an oil content, organic nitrogen, and SS with a simpler facility.SOLUTION: A drainage treatment method comprises: a floc formation step of adding a cationic organic polymer flocculant to water to be treated including an oil content, organic nitrogen, and SS to cause them to form floc; a solid-liquid separation step of performing solid-liquid separation of the water to be treated having the formed floc to obtain treated water; and a modification treatment step of carrying out modification treatment to the water to be treated before the floc formation step so that the floc formed in at least the floc formation step has floc strength required for the solid-liquid separation, thereby allowing the treated water obtained by the solid-liquid separation to have clarity.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wastewater treatment method and a wastewater treatment device. [Background technology]

[0002] Traditionally, wastewater containing oil, organic nitrogen, suspended solids (SS), etc. has been discharged from factories and business establishments, regardless of the type of business. In particular, wastewater discharged from slaughterhouses, meat processing facilities, meat processing plants, etc. contains a lot of animal blood. The components in such wastewater are mostly organic nitrogen, and also contain oil and SS.

[0003] The general methods of treating wastewater with high organic nitrogen concentrations include pretreatment (primary treatment), biological treatment (secondary treatment), and advanced treatment (tertiary treatment). Pretreatment is a process to remove impurities from wastewater, and includes physicochemical treatment methods (screens, pressure flotation, coagulation and sedimentation, natural solid-liquid separation, etc.). After pretreatment, the wastewater is biologically treated, and if a large amount of nutrients or components that could not be removed by biological treatment remain, advanced treatment is used. Treated water is discharged from the system, but screen residue, oil-containing sludge (flotation separation scum), excess sludge, etc. generated in each process require separate treatment. After removing the water from the screen residue, it is disposed of or composted. Oil-containing sludge and excess sludge go through a sludge treatment process (concentration, dehydration, drying, incineration, etc.) before being finally disposed of or reused.

[0004] JP 2019-37955 A (Patent Document 1) describes an example of a water treatment method and water treatment device for oil-containing wastewater, which includes a flocculation step in which a cationic organic polymer flocculant is added to and mixed with the oil-containing wastewater to form flocs, and a solid-liquid separation step in which the generated flocs are separated from the separated liquid. Patent Document 1 also describes that a natural polymer-based oil removing agent or a synthetic polymer-based oil removing agent is added before the addition of the cationic organic polymer flocculant in the flocculation step.

[0005] Japanese Patent Laid-Open Publication No. 2002-346306 (Patent Document 2) describes a blood wastewater treatment method and blood wastewater treatment system, which includes a coagulation step in which hydrochloric acid and an aqueous solution of ferric chloride are added to blood wastewater to coagulate organic matter in the blood, a step in which a precipitate is precipitated and precipitated by neutralization with an alkali, and a removal step in which the wastewater and the precipitate are separated and the precipitate is removed, and in which a flocculant can be added in the removal step.The document describes that the precipitate is dehydrated using a dehydrator and then disposed of as sludge waste.

[0006] Japanese Patent Laid-Open Publication No. 2014-147859 (Patent Document 3) describes a water treatment method and system in a blood wastewater treatment system which has a settling tank in which a coagulant is added to blood wastewater to separate it into a sedimentation portion containing blood components and an upper wastewater, a microbubble treatment tank in which the upper wastewater is subjected to foam separation using microbubbles to produce separated water, an ozone oxidation treatment tank in which the separated water is subjected to an oxidation treatment to produce sterilized water, and a filtration tank in which the sterilized water is treated with activated carbon to produce reclaimed water, and which has a circulation pump for circulating the treated water through the microbubble treatment tank and the ozone oxidation tank.

[0007] Japanese Patent Laid-Open Publication No. 3-127944 (Patent Document 4) describes a device for recovering and reusing high-quality protein, the main component of which is high-concentration blood discharged from fish, at low cost, and includes the steps of heating high-concentration fish blood juice at 50-55°C to produce a colorless gel, diluting the gel with salt water to produce a dilute solution, adjusting the pH of the dilute solution to produce flocs, adding a polymer coagulant to the dilute solution and flocs to thicken the flocs, separating the thickened flocs by electric flotation, dehydrating the floated sludge to recover high-quality protein, and adding and reusing the recovered protein as a raw material for the factory. It also describes that the treatment device reduces SS and BOD in the wastewater, making wastewater treatment easier.

[0008] Japanese Patent Laid-Open Publication No. 4-27492 (Patent Document 5) describes a water treatment method which includes the steps of adding 5 to 200 wt % of an inorganic flocculant (one type or a mixture of two or more types) relative to the total organic carbon in the animal protein to water containing animal protein, adjusting the pH of the wastewater after addition of the flocculant to 3 or higher, heating the wastewater after the pH adjustment to 60°C or higher, and filtering the wastewater after the heating treatment.

[0009] Japanese Patent Laid-Open Publication No. 3-93689 (Patent Document 6) describes a method and an apparatus for processing recovered products, including a process in which a returned food product (coagulated state) containing or not containing protein is held while being heated and drained and separated, and the coagulated product after draining and separation is fermented and decomposed to produce a recycled product such as fertilizer, and a process in which a returned food product (liquid state) containing or not containing protein is added with a coagulant, a pH adjustment process, a process in which the food product is held while being heated and drained and separated, and the coagulated product after draining and separation is fermented and decomposed to produce a recycled product containing feed ingredients or fertilizer ingredients.

[0010] Japanese Patent Laid-Open Publication No. 2002-143862 (Patent Document 7) describes a method for treating protein-containing wastewater, which includes a step of adding a protein-clotting enzyme to protein-containing wastewater (mainly milk protein) to coagulate the protein, a step of separating the coagulated protein from the liquid after treatment, and a step of biologically treating the liquid. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2019-37955 A [Patent Document 2] JP 2002-346306 A [Patent Document 3] JP 2014-147859 A [Patent Document 4] Japanese Patent Application Publication No. 3-127944 [Patent Document 5] Japanese Patent Application Publication No. 4-27492 [Patent Document 6] Japanese Patent Application Publication No. 3-93689 [Patent Document 7] JP 2002-143862 A Summary of the Invention [Problem to be solved by the invention]

[0012] However, Patent Document 1 does not disclose an effective treatment method for wastewater containing a large amount of organic nitrogen in addition to oil and SS. When performing solid-liquid separation of wastewater containing a large amount of organic nitrogen, there is a problem that the adhesion of the flocs cannot be reduced, and the amount of cationic organic polymer flocculant to be added is large. Similarly, Patent Document 2 does not consider the problem of the adhesion of the flocs during solid-liquid separation. Furthermore, Patent Document 2 requires dehydration of the sediment using a separate dehydrator, requires a separate floating treatment for the oil in the wastewater, making it difficult to remove it simultaneously with components such as BOD and SS, and takes a long time for the treatment process, so there is still room for further study in terms of efficiency.

[0013] In Patent Document 3, blood components and proteins are removed in separate tanks, and therefore the device size and efficiency are not considered to be effective. In addition, the flocculant used in Patent Document 3 is inorganic, and the adhesion of flocs during solid-liquid separation is not considered. Furthermore, Patent Document 3 has problems in that it has many treatment methods with high running costs (microbubble treatment, ozone oxidation treatment, activated carbon treatment, etc.) and does not assume a specific treatment method for the removed solids. Patent Document 4 has problems in that it requires the combined use of heat treatment and pH adjustment to acidic conditions, the polymer flocculant is not cationic, the solid-liquid separation method is high-cost electric flotation separation and requires separate dehydration, and does not assume the simultaneous removal of oil in addition to SS and BOD in wastewater treatment.

[0014] Patent Document 5 leaves room for further study in that it requires the addition of a flocculant, pH adjustment to acidic conditions, and the use of heat treatment in combination, that the flocculant is mainly inorganic, that it does not assume the simultaneous treatment of SS and oil in addition to soluble organic components, and that it does not consider the treatment or disposal method of concentrated sludge after solid-liquid separation methods (filtration and centrifugation).Patent Document 6 leaves room for further study in that it hardly assumes water treatment methods such as the simultaneous removal of oil, SS, and organic matter, that it uses an acid as a coagulant and does not assume a cationic organic polymer flocculant, that the warming (standing) time after heating and the draining and separation time are very long, and that it does not consider the solid-liquid separation method of the flocculated material.

[0015] In Patent Document 7, the target is narrowed down to wastewater containing milk protein or soybean-derived protein that is coagulated by enzymes, enzymes and their auxiliary components (metal salts) are used as coagulants, and cationic organic polymer flocculants are not considered, and while the removal of nitrogen and phosphorus is considered, oil, SS, and organic components (including soluble matter) are not considered. Thus, with conventional methods, it has been difficult to comprehensively solve the various problems associated with the treatment of wastewater that simultaneously contains oil, organic nitrogen, and SS.

[0016] Therefore, the present invention provides a wastewater treatment method and wastewater treatment device that can efficiently treat wastewater containing oil, organic nitrogen, and SS using simpler equipment. [Means for solving the problem]

[0017] As a result of intensive research conducted by the present inventors to solve the above problems, it was discovered that it is effective to carry out a modification treatment for modifying the organic nitrogen in the treated water, which contains oil, organic nitrogen, and SS.

[0018] One aspect of an embodiment of the present invention, which has been completed based on the above findings, is a wastewater treatment method comprising: a flocculation step of adding a cationic organic polymer flocculant to water to be treated containing oil, organic nitrogen, and SS to form flocs; a solid-liquid separation step of subjecting the water to solid-liquid separation to obtain treated water in which the flocs have been formed; and a modification treatment step of performing a modification treatment on the water to be treated prior to the flocculation step so that at least the flocs formed in the flocculation step have a floc strength required for solid-liquid separation and so that the treated water obtained by solid-liquid separation has clarity.

[0019] In one embodiment of the wastewater treatment method according to the embodiment of the present invention, the water to be treated has a weight ratio of organic nitrogen to SS (organic nitrogen / SS) calculated as nitrogen of 0.1 or more.

[0020] In another embodiment of the wastewater treatment method according to the present invention, the molecular weight of the cationic organic polymer flocculant is 5 million or more, and the cationic degree is 50 mol % or more.

[0021] In another embodiment of the wastewater treatment method according to the present invention, the denaturation treatment process includes an acid treatment process in which an acid is added to the water to be treated to make it acidic, and a neutralization treatment process in which an alkaline agent is added to the water to be treated after the acid treatment process to neutralize it.

[0022] In another embodiment of the wastewater treatment method according to the present invention, the denaturing treatment step includes a surfactant addition step of adding a surfactant to neutral or acidic water to be treated.

[0023] In another embodiment of the wastewater treatment method according to the present invention, the denaturing treatment step includes a heat treatment step of heating the water to be treated to a temperature of 50° C. or higher.

[0024] In another embodiment of the wastewater treatment method according to the present invention, the method further comprises an alkaline treatment step of adding an alkaline agent to the water to be treated to make the water alkaline at a pH of 10 or more.

[0025] In another aspect, an embodiment of the present invention provides a wastewater treatment device comprising: a flocculation means including a flocculation tank for adding a cationic organic polymer flocculant to water to be treated, which contains oil, organic nitrogen, and SS, to form flocs; a solid-liquid separation means for performing solid-liquid separation of the water to be treated in which flocs have been formed, to obtain treated water; and a modification treatment means for performing a modification treatment on the water to be treated before it flows into the flocculation means, so that at least the flocs formed in the flocculation tank have a floc strength required for solid-liquid separation and the treated water obtained by the solid-liquid separation means has clarity.

[0026] In one embodiment, the wastewater treatment device according to the present invention further comprises an acquisition means for acquiring water quality information or image information of the water to be treated in the flocculation tank, a prediction means for predicting the water quality of the water to be treated in the flocculation tank based on the water quality information or image information acquired by the acquisition means, and a control means for controlling the injection amount of cationic organic polymer flocculant based on a prediction result of the prediction means. Effect of the Invention

[0027] According to the present invention, there can be provided a wastewater treatment method and a wastewater treatment device capable of efficiently treating wastewater containing oil, organic nitrogen and SS using simpler equipment. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a flow diagram showing an example of a wastewater treatment method according to an embodiment of the present invention. [Diagram 2] FIG. 4 is a flow diagram showing an example of a wastewater treatment method according to a first modified example of the present invention. [Diagram 3] FIG. 11 is a flow diagram showing an example of a wastewater treatment method according to a second modified example of the present invention. [Figure 4] FIG. 11 is a flow diagram showing an example of a wastewater treatment method according to a third modified example of the present invention. [Diagram 5] FIG. 11 is a flow diagram showing an example of a wastewater treatment method according to a fourth modified example of the present invention. [Figure 6] 1 is a schematic diagram showing an example of a wastewater treatment device according to an embodiment of the present invention. [Figure 7] FIG. 2 is a schematic diagram illustrating an example of a wastewater treatment device according to a first modified example of the present invention. [Figure 8] FIG. 11 is a schematic view showing an example of a wastewater treatment device according to a second modified example of the present invention. [Figure 9] FIG. 11 is a schematic view showing an example of a wastewater treatment device according to a third modified example of the present invention. [Figure 10] FIG. 11 is a schematic view showing an example of a wastewater treatment device according to a fourth modified example of the present invention. [Figure 11] FIG. 2 is a cross-sectional view showing an example of a mechanical solid-liquid separation means according to an embodiment of the present invention. [Figure 12] 1 is a schematic diagram illustrating an example of an operating condition support system for a wastewater treatment device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. Note that the embodiment shown below is an example of an apparatus and method for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the structure, arrangement, etc. of the components to those described below.

[0030] (Wastewater treatment method) As shown in FIG. 1, the wastewater treatment method according to the embodiment of the present invention includes a modification treatment step of modifying organic nitrogen in the water to be treated, a flocculation step of adding a cationic organic polymer flocculant to the modified water to be treated and mixing it to form flocs, and a solid-liquid separation step of separating the water to be treated in which flocs have been formed into flocs and a separation liquid (treated water).

[0031] <Water to be treated> The water to be treated is not particularly limited as long as it is wastewater containing oil, organic nitrogen, and SS. For example, wastewater generated in various factories such as slaughterhouses, meat processing facilities, meat processing plants, food processing plants, food manufacturing plants, fertilizer manufacturing plants, machine factories, and automobile factories can be mentioned. Other examples include wastewater (e.g., kitchen wastewater) generated in various facilities such as shopping centers, restaurants, supermarkets, hotels, and hospitals. The water to be treated may also contain oil, organic nitrogen, and organic or inorganic matter other than organic nitrogen. SS may be organic or inorganic.

[0032] Oil refers not only to oils that are liquid at room temperature, but also to fats that are solid at room temperature, i.e., all types of oils and fats. For example, oils include vegetable oils, animal oils, mineral oils, etc., and one or more of these oils are contained. The state of oil in wastewater is that it is emulsified with water, or the water and oil are separated, or the above states are mixed. Generally, the oil concentration in wastewater is measured as a hexane extractable substance (JIS K0102:2019).

[0033] Organic nitrogen refers to the nitrogen components contained in organic matter, including, for example, proteins, amino acids, nucleic acids, amide compounds such as urea, and azo compounds. Total nitrogen is a combination of organic nitrogen and inorganic nitrogen. Inorganic nitrogen is divided into ammonia nitrogen, nitrite nitrogen, and nitrate nitrogen.

[0034] The organic nitrogen contained in the water to be treated is not particularly limited, and may contain one or more selected from the above-mentioned proteins, amino acids, nucleic acids, amide compounds such as urea, and azo compounds. The water to be treated may further contain inorganic nitrogen at the same time. The organic nitrogen may be any of animal, vegetable, and artificially synthesized substances. In general, the organic nitrogen concentration in wastewater is measured as the value obtained by subtracting ammonia nitrogen from Kjeldahl nitrogen.

[0035] The water to be treated may contain organic matter. The organic matter may contain all of the above-mentioned oil or organic nitrogen and organic matter other than the above-mentioned oil or organic nitrogen, or may contain organic matter other than the above-mentioned oil or organic nitrogen in addition to the above-mentioned oil or organic nitrogen. The organic matter may be one or more organic matter such as carbohydrates, proteins, lipids, nucleic acids, vegetable oils, animal oils, mineral oils, alcohols, fatty acids, surfactants, paints, etc. The organic matter may be a substance derived from animal or vegetable oils or a chemically synthesized substance. It may be a substance produced from the above-mentioned substance or a decomposition product of the above-mentioned substance. The organic matter contained in the water to be treated according to this embodiment is not particularly limited, but may further contain inorganic matter.

[0036] SS (Suspended Solids) refers to solid suspended matter floating in wastewater, and refers to the material remaining on filter paper with a pore size of 1 μm when filtered through filter paper. SS includes inorganic and organic substances. Inorganic SS includes soil-derived components and clay components. Organic SS includes components derived from animal, plant and microbial cells and factories. The SS contained in the treated water of this embodiment is not particularly limited, but contains a large amount of SS derived from animal meat pieces, oil, and blood components.

[0037] The temperature of the water to be treated is not particularly limited, but is preferably 5°C to 55°C, and can be, for example, 20°C to 50°C. When heat treatment is used in the denaturation treatment step described later, the temperature is preferably 50°C to 70°C, and more preferably 55°C to 70°C. If the temperature of the water to be treated is low and the temperature is lower than the melting point of the oil contained therein, the oil will become solid, and the treatment may be insufficient. In addition, if the water temperature is extremely high, the components containing organic nitrogen may be excessively denatured, and the treatment may be insufficient when acid treatment, surfactant treatment, or alkali treatment is selected as the denaturation treatment. Even when heat treatment is selected as the denaturation treatment, it is necessary to heat the water to be treated appropriately to denature the components containing organic nitrogen. Therefore, it is necessary to set the water temperature within an appropriate range.

[0038] When the ratio of organic nitrogen and SS in the water to be treated, which contains oil, organic nitrogen and SS, is large, the adhesion of the flocs does not decrease even if a cationic organic polymer flocculant is added to perform flocculation treatment in the flocculation step, and poor flocculation and poor separation may occur. In this embodiment, the flocs are weakened in adhesion and the floc strength required for solid-liquid separation is improved by performing a modification treatment on the water to be treated, which contains organic nitrogen (in nitrogen equivalent) and SS (organic nitrogen / SS) of 0.1 or more. This makes it possible to suppress poor flocculation in the subsequent flocculation step and poor separation in the solid-liquid separation step, and to efficiently treat the flocs and obtain clear treated water. If the modification treatment is not performed, the adhesion of the flocs becomes very strong, the amount of chemicals added increases, poor floc formation occurs, solid-liquid separation may not be performed sufficiently, or the clarity of the treated water may be impaired.

[0039] In one embodiment, the weight ratio of organic nitrogen (in nitrogen equivalent) to SS (organic nitrogen / SS) is preferably 0.1 or more, more preferably 0.15 or more, and even more preferably 0.18 or more. The higher the weight ratio of organic nitrogen (in nitrogen equivalent) to SS (organic nitrogen / SS), the higher the adhesion of the flocs in the flocculation step. Therefore, there is no particular upper limit, but the weight ratio of organic nitrogen (in nitrogen equivalent) to SS (organic nitrogen / SS) can be 5 or less, further 3 or less, further 1.5 or less, and further 0.5 or less.

[0040] In addition, the organic nitrogen (nitrogen equivalent) and COD contained in the treated water Mn Ratio of organic nitrogen / COD Mn ) is preferably 0.1 or more. There is no particular upper limit, but organic nitrogen (nitrogen equivalent) and COD Mn Ratio of organic nitrogen / COD Mn ) is preferably 3 or less, more preferably 1.5 or less, and even more preferably 0.5 or less.

[0041] In addition, the ratio (organic nitrogen / n-Hex) of the organic nitrogen (nitrogen equivalent) and the oil concentration (n-Hex) contained in the water to be treated is preferably 0.5 or more. There is no particular upper limit, but the ratio (organic nitrogen / n-Hex) of the organic nitrogen (nitrogen equivalent) and the oil concentration (n-Hex) is preferably 5 or less, more preferably 3 or less, and even more preferably 2 or less. The range of n-Hex contained in the water to be treated is typically 150 mg / L or more and 7,000 mg / L or less, more typically 170 mg / L or more and 6,500 mg / L or less, and even more preferably 1,000 mg / L or more and 6,500 mg / L or less. The water to be treated suitable for this embodiment has SS, COD Mn , and the ratio of organic nitrogen to n-Hex is relatively high. By subjecting such water to the modification treatment process according to this embodiment, the flocculation effect and separability can be improved to obtain clear treated water, making it possible to efficiently treat wastewater containing oil, organic nitrogen, and SS with simpler equipment.

[0042] <Cationic organic polymer flocculant> -kinds- As the cationic organic polymer flocculant, one or more selected from homopolymers or copolymers of cationic monomers, copolymers of cationic monomers and nonionic monomers, copolymers of cationic monomers and anionic monomers, etc. In this embodiment, the term "organic polymer" is used to clearly distinguish it from inorganic flocculants such as polyaluminum chloride and polyferric sulfate, but it is generally simply called a polymer flocculant.

[0043] As the cationic monomer, one or more selected from dialkylaminoalkyl (meth)acrylates or their neutralized salts, tertiary salts, or quaternary salts can be used. For example, dimethylaminoethyl (meth)acrylate or their neutralized salts, tertiary salts, or quaternary salts can be used. Among these, a quaternary salt of dimethylaminoethyl (meth)acrylate is preferred, and an ammonium salt is more preferred.

[0044] As the nonionic monomer, one or more selected from (meth)acrylamide, N,N-dimethyl(meth)acrylamide, (meth)acrylonitrile, vinyl acetate, etc. can be used. As the anionic monomer, one or more selected from (meth)acrylic acid, sodium (meth)acrylate, itaconic acid, maleic acid, fumaric acid, 2-(meth)acrylamide-methylpropanesulfonic acid, and metal salts or ammonium salts thereof can be used.

[0045] It should be noted that (meth)acrylate is a concept that includes both acrylate and methacrylate, (meth)acrylic acid is a concept that includes both acrylic acid and methacrylic acid, and further, (meth)acrylamide is a concept that includes both acrylamide and methacrylamide.

[0046] In addition, as the cationic organic polymer flocculant, in addition to non-amidine-based polymer flocculants, it is possible to use amidine-based polymer flocculants having amidine units, and polymer flocculants which are mixtures of amidine-based polymer flocculants and non-amidine-based polymer flocculants can also be used.

[0047] The form of the cationic organic polymer flocculant is not particularly limited, and examples thereof include powder and liquid forms (dispersions and emulsions).

[0048] -Cation degree- Although the type of raw material monomer and the form of the organic polymer are not limited, this embodiment uses an organic polymer containing 50 mol% or more of cationic monomer in all monomer units, that is, a cationic organic polymer flocculant having a cationic degree of 50 mol% or more. That is, the cationic organic polymer flocculant used in this embodiment is produced by polymerizing raw material monomers containing 50 mol% or more of cationic monomer, and the amount of cationic monomer is more preferably 60 mol% or more, even more preferably 70 mol% or more, and particularly preferably 80 mol% or more.

[0049] Furthermore, a cationic organic polymer flocculant consisting essentially of cationic monomers (100 mol%) can also be used. The cationic degree can be defined as the proportion (mol%) of cationic monomers contained in the raw material monomers of the organic polymer.

[0050] In general, oils and other substances contained in wastewater are finely dispersed in the wastewater by surfactants and alkaline components, and the surfaces of the oil particles are negatively charged. Compared to the zeta potential of general pollutants, the zeta potential of oil particles is significantly lower, and even if a normal cationic organic polymer flocculant is added, flocs are not formed, or even if flocs are formed, they are not strong enough to withstand mechanical solid-liquid separation.

[0051] On the other hand, when a cationic organic polymer flocculant with a cationic degree of 50 mol% or more is added and mixed, the highly positively charged (high positive charge density) molecular chains capture the finely dispersed oil in the wastewater, forming strong flocs that can withstand mechanical solid-liquid separation.

[0052] -Molecular weight- The molecular weight of the cationic organic polymer flocculant is not particularly limited, but it is preferable that the molecular weight is 5 million or more, more preferably 6 million or more, particularly 7 million or more, and of these, it is preferable that the molecular weight is 8 million or more. This molecular weight is a value measured and calculated by the intrinsic viscosity method, and the details of the measurement and calculation method are described on pages 112 to 116 of "Polymer Flocculant - Usage Guide" (Tokyo Metropolitan Sewerage Service Co., Ltd., published in March 2002).

[0053] Because the oil in wastewater is finely dispersed throughout the wastewater, adding a normal cationic organic polymer flocculant makes it difficult to form flocs, or even if flocs are formed, they are not strong enough to withstand mechanical solid-liquid separation. On the other hand, if a cationic organic polymer flocculant with a cationic degree of 50 mol% or more and a molecular weight of 5 million or more is used, the long molecular chains can capture the oil that is finely dispersed throughout the wastewater, forming stronger flocs that can withstand mechanical solid-liquid separation.

[0054] -viscosity- From the same viewpoint as the molecular weight, the property of the cationic organic polymer flocculant can also be defined by the solution viscosity. Specifically, when the cationic organic polymer flocculant is dissolved in pure water at 1 g / L, the viscosity of the solution is preferably 100 mPa s or more, more preferably 120 mPa s or more, and particularly preferably 150 mPa s or more.

[0055] Furthermore, when the cationic organic polymer flocculant is dissolved in pure water at 2 g / L, the viscosity of the resulting aqueous solution is preferably 200 mPa·s or more, more preferably 220 mPa·s or more, and particularly preferably 250 mPa·s or more.

[0056] The above viscosity was measured at 25°C for 60 min at either concentration of 1 g / L or 2 g / L using a B-type viscometer and spindle SB2 as specified in Appendix 1 of JIS K7117-1:1999 (reference). -1 The value is measured at a rotational speed of 1000 rpm. The spindle is also called the rotor.

[0057] -solvent- The cationic organic polymer flocculant is preferably used as a flocculant solution dissolved or dispersed in a solvent. The solvent is not particularly limited, but for example, one or more selected from pure water (including distilled water), tap water, industrial water, groundwater, treated water from various wastewater treatment processes, seawater, etc. are usable. From the viewpoint of maximizing the flocculating power of the cationic organic polymer flocculant, it is preferable to use pure water or tap water. On the other hand, from the viewpoint of economic efficiency, it is preferable to use industrial water, groundwater, or treated water from various wastewater treatment processes. However, the above are merely examples and are not limited to these.

[0058] -Injection concentration- Whether the cationic organic polymer flocculant is diluted or not, the amount of cationic organic polymer flocculant (active ingredient) injected is preferably from 1 mg / L to 500 mg / L, more preferably from 5 mg / L to 400 mg / L, and particularly preferably from 10 mg / L to 300 mg / L.

[0059] <Acid> In the modification treatment step, the acid is used to make the pH of the water to be treated acidic and to modify the water to be treated, which contains organic nitrogen, SS, and oil.

[0060] The type of acid is not particularly limited, but inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and boric acid are generally used. In particular, the use of sulfuric acid is preferable due to problems in maintaining and managing the reaction tank. An inorganic coagulant may be added before or at the same time as the addition of the pH adjuster. Types of inorganic coagulants that can be used include aluminum sulfate, polyaluminum chloride (PAC), aluminum chloride, polyferric sulfate (polyferric), ferric sulfate, ferric chloride, or mixtures of these. The use of an inorganic coagulant may allow the amount of cationic organic polymer coagulant used to be reduced.

[0061] In the denaturation treatment step, it is preferable to add an acid to the water to be treated to create an acidic condition, thereby denaturing and coagulating components containing organic nitrogen, such as proteins, in the water to be treated. The denaturation and coagulation of organic nitrogen facilitates the subsequent formation of flocs. In addition, water to be treated with a high organic nitrogen ratio exhibits the effect of preventing the adhesion of flocs in the subsequent flocculation step from being significantly reduced in handleability.

[0062] <Surfactant> Surfactants are used in the denaturation treatment process to denature the water to be treated, which contains organic nitrogen, SS, and oil. Surfactants are broadly classified into ionic surfactants and nonionic surfactants. Ionic surfactants are further classified into anionic surfactants, cationic surfactants, and amphoteric surfactants.

[0063] There is no particular limit to the type of surfactant, but anionic surfactants are preferred.Specific examples include fatty acid sodium, fatty acid potassium, alpha sulfo fatty acid ester sodium, linear alkylbenzenesulfonate sodium, alkyl sulfate ester sodium, alkyl ether sulfate sodium, alpha olefin sulfonate sodium, alkyl sulfonate sodium, and sodium lauryl sulfate.There is no particular limit to the surfactant used, but sodium lauryl sulfate (sodium dodecyl sulfate) is preferred.

[0064] In the denaturation treatment step, by adding a surfactant to the water to be treated, components containing organic nitrogen such as proteins in the water to be treated are denatured into a form suitable for floc formation and solid-liquid separation. The denaturation of organic nitrogen facilitates the subsequent floc formation by the cationic organic polymer flocculant. In addition, water to be treated with a high organic nitrogen ratio exhibits the effect of preventing the adhesion of flocs in the subsequent floc formation step from being significantly reduced in handleability.

[0065] The surfactant may be in any form, such as solid or liquid, but may be diluted or dissolved in a solvent before injection. It may also be injected in powder form or as a liquid.

[0066] <Alkaline agent> The alkaline agent is used in the modification treatment step to modify the treated water, which contains organic nitrogen, SS, and oil, or for neutralization in the neutralization treatment step.

[0067] The type of alkaline agent includes sodium hydroxide, magnesium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, calcium carbonate, potassium carbonate, magnesium carbonate, sodium hydrogen carbonate, ammonium hydroxide, ammonium carbonate, or hydrates thereof, etc. There is no particular limitation on the alkaline agent used, but sodium hydroxide is preferred.

[0068] In the denaturation treatment step, an alkaline agent is added to the water to be treated, which denatures components in the water, such as proteins, that contain organic nitrogen. Denaturation of the organic nitrogen facilitates the subsequent formation of flocs. In addition, water to be treated with a high organic nitrogen ratio exhibits the effect of preventing the adhesion of flocs in the subsequent flocculation step from decreasing significantly in handleability.

[0069] <Other drugs> This embodiment does not limit the use of any agent other than the above-mentioned agent and cationic organic polymer flocculant. Specifically, before adding the cationic organic polymer flocculant, one or more agents such as a known inorganic flocculant or an organic polymer coagulant (a flocculant with a lower molecular weight than the cationic organic polymer flocculant) can be added.

[0070] Inorganic coagulants include aluminum sulfate, polyaluminum chloride (PAC), aluminum chloride, polyferric sulfate (polyferric), ferric sulfate, ferric chloride, or a mixture of these. Organic polymer coagulants include condensation polyamines, dicyandiamide-formaldehyde condensates, polyethyleneimine, polyvinyl imidaline, polyvinyl pyridine, diallylamine salt-sulfur dioxide copolymers, polydimethyl diallyl ammonium salts, polydimethyl diallyl ammonium salt-sulfur dioxide copolymers, polydimethyl diallyl ammonium salt-acrylamide copolymers, polydimethyl diallyl ammonium salt-diallyl amine hydrochloride derivative copolymers, and allylamine salt polymers.

[0071] Specific examples of the condensation polyamine include a condensation product of an alkylene dichloride and an alkylene polyamine, a condensation product of aniline and formalin, a condensation product of an alkylene diamine and epichlorohydrin, a condensation product of ammonia and epichlorohydrin, etc. Examples of the alkylene diamine that is condensed with epichlorohydrin include dimethylamine, diethylamine, methylpropylamine, methylbutylamine, dibutylamine, etc.

[0072] (Modification process) In the modification treatment process shown in Figure 1, the organic nitrogen components contained in the inflowing treated water, which contains oil, organic nitrogen, and SS, are modified. The purpose of this process is a pretreatment process to form good flocs in a short time and improve the water quality of the separated liquid in the subsequent flocculation process.

[0073] In the conventional flocculation by adding only a cationic organic polymer flocculant, it was possible to treat oil and SS, but when the content of organic nitrogen in addition to oil and SS increases in the water to be treated, problems such as the occurrence of floc stickiness and an increase in the amount of chemicals to be added become apparent. According to this embodiment, by carrying out a modification treatment step before the flocculation step, it is possible to suppress the occurrence of floc stickiness and reduce the amount of chemicals to be added.

[0074] The denaturing treatment step may include an acid treatment step of adding an acid to the water to be treated to make it acidic, and a neutralization treatment step of adding an alkaline agent to the water to be treated after the acid treatment step to neutralize it, as shown in Fig. 2. Alternatively, the method may include a surfactant addition step of adding a surfactant to the water to be treated, as shown in Fig. 3. Alternatively, the method may include a heat treatment step of heating the water to a temperature of 50°C or higher, as shown in Fig. 4. Alternatively, the method may include an alkali treatment step of adding an alkaline agent to the water to be treated to make it alkaline, with a pH of 10 or higher, as shown in Fig. 5.

[0075] In the acid treatment step and neutralization treatment step shown in Fig. 2, acid is injected into the water to make it acidic, the organic nitrogen components are denatured, and then an alkaline agent is injected to perform neutralization. The pH of the acidic condition is preferably 5 or less, more preferably 4 or less, and even more preferably 3.5 or less, more preferably 1 or more, and even more preferably 2 to 3. The pH during neutralization is preferably 6 to 7.5, more preferably 6 to 7, and even more preferably 6.5 to 7.

[0076] In the surfactant addition step shown in Fig. 3, a denaturing treatment is performed by injecting a surfactant into the water to be treated. The concentration of the surfactant injected (relative to the purity) is preferably 50 mg / L to 300 mg / L, more preferably 100 mg / L to 250 mg / L, and particularly preferably 150 mg / L to 200 mg / L. In the surfactant addition step, it is suitable to add the surfactant under neutral conditions, preferably under acidic conditions, and more preferably after adjusting the pH to 5 to 7, and further preferably to weakly acidic conditions of 5 to 6.

[0077] 4, the denaturing treatment is performed by heating the water to be treated. The water temperature after the heat treatment is preferably 50° C. or higher and 80° C. or lower, and more preferably 55° C. or higher and 70° C. or lower. In addition, the water temperature in methods other than the heat treatment is preferably 5° C. or higher and 55° C. or lower, and more preferably 20° C. or higher and 50° C. or lower.

[0078] In the alkaline treatment step shown in Fig. 5, an alkaline agent is injected into the water to be treated, and the water is denatured under alkaline conditions. The alkaline conditions have a pH of 10 or higher. In any of the denaturation treatment steps described above, it is preferable to provide a mixing step after the injection of the agent, although there is no particular restriction.

[0079] In the modification process, when stirring and mixing with a stirring device, there is no particular restriction on the stirring speed, but -1 More than 300min -1 Less than 30 minutes (times / minute) is preferable. -1 Over 200min -1 Less than 40 minutes is preferable. -1 More than 150min -1 The following are particularly preferred:

[0080] It is preferable to shorten the time required for treatment by subjecting the water to the modification treatment step, i.e., the residence time in the equipment involved in the modification treatment step, to a relatively short time. The residence time of the water in the modification treatment step is preferably 1 minute or more and 30 minutes or less, more preferably 3 minutes or more and 20 minutes or less, and particularly preferably 5 minutes or more and 15 minutes or less.

[0081] In order to check the pH of the water to be treated, it is preferable to install a pH measuring means for the water to be treated before and after the pH adjustment. An example of the pH adjustment means is a pH measuring device that continuously measures pH. In particular, a pH meter that can transfer and record the results to a separate recording device is preferable.

[0082] (Flocculation process) In the flocculation process, a cationic organic polymer flocculant is injected into and mixed with the water to be treated that has been treated in the modification process, forming flocs. Specifically, a cationic organic polymer flocculant is injected into and mixed with the water to be treated that has passed through the above-mentioned modification process. Through the above process, components in the water to be treated, such as oil, organic nitrogen, SS, and organic matter, react with the cationic organic polymer flocculant to form flocs. Furthermore, through the formation of flocs, the components that have been captured by the flocs are separated as a separated liquid.

[0083] In the flocculation process, when mixing with a stirring blade or the like, there is no particular restriction on the stirring speed, but it is recommended to use a stirring speed of 20 min -1 More than 300min -1 Less than 30 minutes (times / minute) is preferable. -1 Over 200min -1 Less than 40 minutes is preferable. -1 More than 150min -1 The following are particularly preferred:

[0084] This flocculation step is preferably divided into two or more steps, a high-speed stirring step and a low-speed stirring step. High-speed stirring is when the stirring speed of the stirring blade is 200 min -1 (times / min) or more. Low-speed mixing means a mixing speed of 200 min -1 (times / min). In the high-speed mixing process, the cationic organic polymer flocculant is uniformly dispersed and mixed by high-speed mixing. In the low-speed mixing process, flocs are grown by low-speed mixing.

[0085] The residence time required for sufficient growth of flocs in the treated water varies depending on the type of equipment and conditions. In this embodiment, for example, the residence time in the equipment involved in the growth of flocs is preferably 1 minute or more and 30 minutes or less, more preferably 3 minutes or more and 20 minutes or less, and particularly preferably 5 minutes or more and 15 minutes or less.

[0086] The water temperature during the flocculation step is not particularly limited, but is preferably 5° C. to 55° C., more preferably 20° C. to 50° C., except for the heat treatment. When the heat treatment is used, the temperature is preferably 55° C. to 70° C.

[0087] In the flocculation step, the cationic organic polymer flocculant can be injected into the water to be treated in two or more separate injections. It is also possible to inject one or more inorganic flocculants, either alone or together with the cationic organic polymer flocculant, into the water to be treated, and then inject further cationic organic polymer flocculant into the water to be treated after the injection. When the inorganic flocculant is injected, it is preferable that the injection position is upstream of the injection position of the cationic organic polymer flocculant.

[0088] Flocculation removes oil and SS from the treated water, and simultaneously removes organic nitrogen and organic matter. Furthermore, the flocs formed have low adhesion and high floc strength, which greatly improves handling in the subsequent stages.

[0089] (solid-liquid separation process) In the solid-liquid separation step, the flocs formed in the flocculation step and the separated liquid are separated into solid and liquid by mechanical means (mechanical solid-liquid separation step). Specifically, a mechanical solid-liquid separation means is provided. The water to be treated containing the flocs formed in the flocculation step is supplied to the mechanical solid-liquid separation means and separated into flocs and separated liquid by solid-liquid separation. During separation, the flocs are concentrated and dehydrated at the same time, and the water generated during this process is also separated as separated liquid.

[0090] By using a mechanical solid-liquid separation means in the solid-liquid separation process, the flocs after solid-liquid separation do not need to be dehydrated by a separate dehydrator, and the solid-liquid separation time can be shortened. The method of disposing of the flocs after mechanical solid-liquid separation is not particularly limited, but includes industrial waste disposal, raw material for methane fermentation, reforming as fuel for combustion or incineration, combustion improver for incineration, separating and extracting specific oils from oil flocs, and using as fertilizer. The separated liquid may be subjected to separate physicochemical or biological treatment, but if the regulated components in the treated water have been treated to a satisfactory concentration, it can also be discharged as treated water after disinfection.

[0091] According to the wastewater treatment method of the embodiment of the present invention, by carrying out a modification treatment step for modifying organic nitrogen components in the water to be treated before the flocculation step, it is possible to reduce an increase in the adhesion of flocs in the flocculation step, and to perform treatment more efficiently and stably than in the past while suppressing problems such as adhesion of flocs to equipment such as the coagulation tank, the agitator of the coagulation tank, and piping. The modification treatment step can exert its effect in a relatively short treatment time of about 30 minutes at most, so that the treatment time can be shortened.

[0092] (Wastewater treatment equipment) As shown in FIG. 6, a wastewater treatment device according to an embodiment of the present invention includes a modification treatment means 1 that modifies organic nitrogen in water to be treated that contains oil, organic nitrogen, and SS, a flocculation means 2 that adds a cationic organic polymer coagulant to the modified water to be treated and mixes it to form flocs in a flocculation tank 21, and a solid-liquid separation means 3 that separates the water to be treated in which flocs have been formed into flocs and a separated liquid.

[0093] (Denaturation Treatment Means 1) The modification treatment means 1 performs a treatment to modify the organic nitrogen in the water to be treated in the modification treatment tank 11 by any of the following methods. Specifically, the modification treatment means 1 can change its device form depending on the mode of the modification treatment. The number of treatment tanks used as the modification treatment means 1 is not particularly limited. In addition, the modification treatment performed by the modification treatment means 1 may be one or a combination of two or more of the modification treatments shown below. When a chemical agent is injected into the modification treatment means 1 for the modification treatment, a stirring device can be provided to thoroughly mix the water to be treated with the chemical agent. The stirring device is not particularly limited, but examples thereof include stirring blades. In addition, the shape, size, number, etc. of the stirring device are not particularly limited.

[0094] The modification treatment means 1 according to one embodiment can include an acid treatment means 1a and a neutralization treatment means 1b, as shown in Fig. 7. The acid treatment means 1a includes an acid treatment tank 12, an agitation device 12a for agitating the acid treatment tank 12, an acid storage tank 13, and an acid injection device (not shown) for injecting acid from the acid storage tank 13 into the acid treatment tank 12. The acid treatment means 1a performs an acid treatment step in which acid is added from the acid storage tank 13 to the water to be treated, thereby making the water to be treated in the acid treatment tank 12 acidic.

[0095] The neutralization treatment means 1b includes a neutralization tank 14, an agitation device 14a for agitating the neutralization tank 14, an alkaline agent storage tank 15, and an alkaline agent injection device (not shown) for injecting an alkali from the alkaline agent storage tank 15 into the neutralization tank 14. In the neutralization treatment means 1b, an alkaline agent is added from the alkaline agent storage tank 15 to the water to be treated after the acid treatment step by the acid treatment means 1a, thereby carrying out neutralization treatment.

[0096] As another embodiment of the modification treatment means 1, as shown in Fig. 8, a surfactant treatment means 1c for adding a surfactant to the water to be treated can be provided. The surfactant treatment means 1c includes a surfactant treatment tank 16, a surfactant storage tank 17, a surfactant injector (not shown), and an agitator 16a. The water to be treated flows into the surfactant treatment tank 16, into which a surfactant is injected from the surfactant storage tank 17 by the surfactant injector, and the water is mixed by the agitator 16a and modified by the surfactant. The surfactant can be injected into the flocculation tank 21 in addition to being injected into the surfactant treatment tank 16. Alternatively, an injection point may be provided in the piping between the surfactant treatment tank 16 and the flocculation tank 21, and the water may be injected from the injection point.

[0097] As a further embodiment of the denaturation treatment means 1, as shown in Fig. 9, a heat treatment means 1d for heat-treating the temperature of the water to be treated can be provided. The heat treatment means 1d includes a heat treatment tank 18, a heat treatment device 19, and an agitator 18a. The water to be treated flows into the heat treatment tank 18, is heated by the heat treatment device 19, is mixed by the agitator 18a, and is denatured by heating. The heat treatment device 19 is not particularly limited, and examples thereof include an electric heater, steam, a heat pump, and the like.

[0098] As another embodiment of the modification treatment means 1, as shown in Fig. 10, an alkaline treatment means 1e for adding an alkaline agent to the water to be treated is provided. The alkaline treatment means 1e is provided with an alkaline treatment tank 111, an alkaline agent storage tank 112, an alkaline agent injection device (not shown), and an agitation device 111a. The water to be treated flows into the alkaline treatment tank 111, an alkaline agent is injected from the alkaline agent storage tank 112 by the alkaline agent injection device, the water is mixed by the agitation device 111a, and the water is modified by the alkaline agent. There is no particular limitation on the place where the alkaline agent is injected, and any place before the injection of the cationic organic polymer flocculant may be selected, such as the alkaline treatment tank 111, between the alkaline treatment tank 111 and the subsequent flocculation tank 21, or the subsequent flocculation tank 21.

[0099] (Flock forming means 2) The flocculation means 2 injects and mixes a cationic organic polymer flocculant into the water to be treated that has passed through the modification treatment means 1. Specifically, it comprises a flocculation tank 21, a dissolution tank 22, a cationic organic polymer flocculant injector (not shown), and an agitator 21a. The specific configurations of these devices are not particularly limited, and it is sufficient that the cationic organic polymer flocculant is injected into the water to be treated in the flocculation tank 21 and mixed therein.

[0100] It is also possible to install two or more flocculation tanks 21. When the flocculation tank 21 is a single tank as shown in FIG. 6, it is preferable that the agitator 21a has a function of high-speed agitation and low-speed agitation. Alternatively, it is also possible to install two or more agitators, each having a function of high-speed agitation or low-speed agitation. When the flocculation tank 21 is two or more tanks, it is also possible to install an agitator 21a having a function of high-speed agitation or low-speed agitation in each flocculation tank 21. The number and arrangement of these flocculation tanks 21 and agitators 21a are not particularly limited. Furthermore, when a chemical other than a cationic organic polymer flocculant is used, it is preferable to install a chemical injection device for each chemical.

[0101] The water to be treated after the denaturation treatment flows into the flocculation tank 21, and a cationic organic polymer flocculant supplied from the dissolution tank 22 is injected into the flocculation tank 21 by an injection device. The water to be treated and the cationic organic polymer flocculant are mixed by an agitator 21a. The dissolution tank 22 is not particularly limited as long as it can dilute or dissolve the cationic organic polymer flocculant with a solvent and store it. An agitator (not shown) for dilution or dissolution may be provided in the dissolution tank 22.

[0102] (Solid-liquid separation means 3) As the solid-liquid separation means 3, various devices can be used as long as they are a solid-liquid separator 31 for performing solid-liquid separation into flocs and separated liquid from the floc-containing water to be treated that has flowed in from the flocculation tank 21, and such devices can be used, including gravity settling equipment, pressure flotation equipment, mechanical solid-liquid separators, etc. Among these, in particular, the use of a mechanical solid-liquid separator that mechanically separates the water to be treated into solid and liquid by pressurization, centrifugal force, reduced pressure (vacuum exhaust), or a combination of these can be used to make wastewater treatment more efficient.

[0103] As the mechanical solid-liquid separation device, for example, a concentrator conventionally used for sludge concentration or a dehydrator used for sludge treatment can be used. The concentrator is not particularly limited, but for example, a screw concentrator, a belt concentrator, a centrifugal concentrator, an elliptical plate concentrator, etc. can be used alone or in combination. The dehydrator is not particularly limited, but the same type of device as that used for further dehydration after solid-liquid separation described below can be used.

[0104] 11 is an example of a partial cross-sectional view of a mechanical solid-liquid separator when a mechanical solid-liquid separator is used as the solid-liquid separator 31. The mechanical solid-liquid separator has a floc moving means 35 for continuously treating flocs. The floc moving means 35 has a belt driving means 32 such as a rotating roll, and a belt 36 stretched around the belt driving means 32, and the separation liquid containing flocs supplied from the flocculation tank 21 is supplied onto the belt 36 through an inlet 33 at the top of the apparatus.

[0105] A part or the whole of the belt 36 is made of filter cloth, and water in the flocs 9 is separated into solid and liquid while moving, the separated liquid is captured by the capture means 34 below the belt, and the separated flocs (sludge) are discharged from the discharge port 39. After discharging the flocs, the belt 36 returns to the inlet 33 side, and the flocs are supplied again, but before returning to the inlet side, washing water from the belt washing means 37 may be sprayed to wash the belt 36.

[0106] The mechanical solid-liquid separation apparatus of Fig. 11 is suitable for continuous treatment of the separated liquid containing flocs, and more preferably, a pressurizing means 41 is provided. The pressurizing means 41 is an apparatus for pressurizing (squeezing) the flocs 9, and has, for example, one or more pressurizing plates 42 arranged before the discharge port 39.

[0107] The pressure plate 42 is inclined from the vertical plane toward the inlet 33, and there is a gap between its lower end and the belt 36. When the flocs 9 pass through the gap, they are pressed against the belt 36 by the pressure plate 42 and compressed (squeezed). The pressure at this time can be adjusted by changing one or more of the pressure conditions, which are the size of the gap, the inclination angle and number of the pressure plates 42, the moving speed and supply amount of the flocs, etc.

[0108] The pressurizing means 41 is not limited to the pressurizing plate 42, and a pressurizing member of another shape, such as a pressurizing roll, may be used. In either case, the pressurizing means 41 can efficiently reduce the moisture content of the flocs. The pressure applied to the flocs 9 can be appropriately changed depending on the apparatus and solid-liquid separation conditions, but is preferably 200 kPa or less, particularly preferably 1 kPa to 150 kPa, more preferably 1 kPa to 100 kPa, more preferably 10 kPa or more, still more preferably 15 kPa or more, and particularly preferably 20 kPa or more. The pressure can be adjusted by the pressurizing conditions of the pressurizing plate 42, and in the case of a screw press dehydrator, the internal pressure can be adjusted by adjusting the screw rotation speed and the opening of the outlet.

[0109] In this embodiment, the flocculation tank 21 and the solid-liquid separation device 31 are separate devices, but a device that simultaneously performs the flocculation process and the solid-liquid separation process, such as a centrifugal dehydrator, may also be used. Furthermore, the flocs after solid-liquid separation from the water to be treated can be further dehydrated by a dehydrator used for sludge treatment or the like. The dehydrator used for this dehydration is not particularly limited, and any dehydrator that has been conventionally used for sludge dehydration can be used. Specifically, a screw press dehydrator, a belt press dehydrator, a centrifugal dehydrator, a multiple disk type dehydrator, a multiple disk type screw press dehydrator, a rotary pressure dehydrator, a vacuum dehydrator, an elliptical disk type dehydrator, or the like can be used.

[0110] The wastewater treatment device according to the embodiment of the present invention is provided with the modification treatment means 1, which allows the organic nitrogen components in the water to be treated to be modified into a form suitable for treatment by the flocculation means 2. The modification treatment means 1 does not require a particularly complicated configuration, and a relatively small device is sufficient for short-term treatment. Therefore, the wastewater treatment device according to the embodiment of the present invention can provide a wastewater treatment device that can efficiently treat wastewater containing oil, organic nitrogen, and SS with simpler equipment.

[0111] Although the present invention has been described with reference to the above embodiment, the description and drawings forming a part of this disclosure should not be understood as limiting the present invention. In other words, the present disclosure is not limited to the above embodiment, and it is of course possible to combine and modify the components to embody the present disclosure without departing from the spirit of the present disclosure.

[0112] For example, an example of an operating condition support system that optimizes the operating conditions of each piece of equipment using the wastewater treatment equipment shown in Figures 6 to 11 is shown in Figure 12. This operating condition support system includes a modification treatment means 1, a flocculation means 2, a solid-liquid separation means 3, an acquisition means 4 that acquires water quality information or image information of the water to be treated in the flocculation tank 21, a prediction means 7 that predicts the water quality of the water to be treated in the flocculation tank 21 based on the water quality information or image information acquired by the acquisition means 4, and a control means 5 that controls the injection amount of a cationic organic polymer flocculant based on the prediction result of the prediction means 7.

[0113] As the acquiring means 4, various devices capable of acquiring the state of the water to be treated in the flocculation tank 21 can be used. For example, water quality measuring devices such as a pH meter, a BOD meter, a COD meter, an MLSS meter, a colorimeter, a turbidity meter, a transparency meter, or an absorptiometer for measuring the quality of the water to be treated, a particle counter for measuring the number of particles in the water to be treated in the flocculation tank 21, or a sensor or a camera for acquiring an image of the suspended state of particles in the flocculation tank 21 can be used. The water quality information or image information acquired by the acquiring means 4 is output from the control means 5 to the prediction means 7 via, for example, the network 6.

[0114] The prediction means 7 receives raw water information, water quality information or image information of the water to be treated in the flocculation tank 21, water quality information of the treated water related to the water quality information or image information, and information on the operating conditions of the wastewater treatment device, all of which have been obtained over a specific period of time in the past (for example, several years), and predicts the future state inside the flocculation tank 21 by water quality analysis or image diagnosis. The raw water information includes pH, hexane extractables concentration, SS, COD Mn , BOD, organic nitrogen concentration, organic nitrogen concentration / SS ratio, organic nitrogen concentration / COD Mn The operating condition information includes the type and injection amount of cationic organic polymer coagulant, the conditions of the modification treatment, the type and addition amount of chemicals used in the modification treatment, etc. The water quality information of the treated water includes the water quality information of the water to be treated in the flocculation tank 21, clarity evaluation information showing the evaluation result of the clarity of the treated water after the solid-liquid separation treatment, the hexane extractables concentration, SS (SS removal rate), COD Mn (COD Mn Examples of the predictive data include the raw water information, the water quality information or image information of the water to be treated in the flocculation tank 21, the water quality information of the treated water, and the information on the operating conditions of the wastewater treatment device. The predicting means 7 stores the raw water information, the water quality information or image information of the water to be treated in the flocculation tank 21, and the operating conditions information of the wastewater treatment device as one combination of teacher data, and accumulates a sufficient amount of data for the combination as an actual value in a storage means (not shown).

[0115] The prediction means 7 predicts the future water quality of the treated water in the flocculation tank 21 and the treated water after solid-liquid separation treatment after a specific period of time based on the real-time water quality information or image information acquired by the acquisition means 4 and the teacher data stored in the storage means. For example, when the predicted water quality of the treated water after solid-liquid separation or the water quality of the treated water in the flocculation tank 21 does not meet a predetermined standard, a prediction model of operation change conditions is created in which the operating conditions are optimized, for example, by adjusting the injection amount of polymer flocculant, so that the water quality of the treated water meets the standard. The creation of the prediction model is not limited to the following, but can be performed by, for example, supervised learning using a known machine learning algorithm such as a neural network, and by optimizing a weighting function between neurons of the neural network.

[0116] The control means 5 receives information on the change in operation conditions from the prediction means 7, and controls at least one of an injection device (not shown) that injects a cationic organic polymer flocculant from the dissolution tank 22, an acid injection device that injects acid from the acid storage tank 13 to the acid treatment tank 12, or an alkaline agent injection device that injects an alkaline agent from the alkaline agent storage tank 15 to the neutralization tank 14, thereby adjusting the injection amount of at least one of the cationic organic polymer flocculant, the acid, and the alkaline agent. Similarly, the control means 5 can automatically control the injection amount of the pH adjuster, the injection amount of the inorganic flocculant, the amount of the water to be treated, the rotation speed and the presence or absence of rotation of the agitator, etc.

[0117] According to the operating condition support system shown in FIG. 12, by being equipped with the acquisition means 4, the control means 5, and the prediction means 7, it becomes possible to treat wastewater containing oil, organic nitrogen, and SS more efficiently, with fewer treatment troubles, and stably for a long period of time. EXAMPLES

[0118] Examples of the present invention will be described below together with comparative examples. These examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

[0119] In this example, the treatment water containing oil, organic nitrogen, and SS was denatured, and a cationic organic polymer flocculant was injected to form flocs. The floc shapes after solid-liquid separation were visually observed, and the quality of the separated liquid (treated water) was analyzed, and the treatment performance of the wastewater treatment method according to the embodiment of the present invention was examined.

[0120] <Test Method> For the test, wastewater from a meat processing plant was obtained as wastewater containing oil, organic nitrogen, and SS. Four types of wastewater (wastewater A, wastewater B, wastewater C, and wastewater D) were obtained by changing the time of collection. For comparison, five types of general oil-containing wastewater (wastewater E, wastewater F, wastewater G, wastewater H, and wastewater I) were also obtained. Note that the wastewaters shown in Tables 1 and 2 include wastewater that does not show the effects of this embodiment in the following description, but all of these wastewaters are examples of wastewater that is effective for the treatment according to this embodiment.

[0121] Table 1 shows an example of water that can be used in this embodiment, which contains oil, organic nitrogen, and SS and has a high organic nitrogen / SS ratio. The pH of wastewater A, wastewater B, wastewater C, and wastewater D was 6.6, 6.7, 6.6, and 6.6, respectively, the organic nitrogen was 242 mg / L, 265 mg / L, 233 mg / L, and 222 mg / L, respectively, the hexane extractable substances (hereinafter, n-Hex) were 266 mg / L, 174 mg / L, 290 mg / L, and 362 mg / L, respectively, and the suspended solids (hereinafter, SS) were 1,170 mg / L, 900 mg / L, 980 mg / L, and 1,230 mg / L, respectively. COD Mn The pH was 838mg / L, 737mg / L, 810mg / L, and 833mg / L, respectively, and the BOD was 2,620mg / L, 1,920mg / L, 2,360mg / L, and 2,230mg / L, respectively. The organic nitrogen / SS ratios of wastewater A, B, C, and D were in the range of 0.18-0.29, and all were above 0.1. The organic nitrogen / n-Hex ratios were all above 0.5.

[0122] [Table 1]

[0123] Table 2 shows the details of typical oil-containing wastewater. These are examples of wastewater quality that is usually obtained from food processing plants and dairy product manufacturing plants, and show examples of wastewater from different industries and raw material components. The organic nitrogen / SS ratio is less than 0.1. Also, the organic nitrogen / COD Mn The ratio and organic nitrogen / n-Hex ratio are both lower than those of the target wastewater in this example, and show an example in which the organic nitrogen content is also low.

[0124] [Table 2]

[0125] Water quality parameters: pH, n-Hex, SS, COD Mn The method for measuring BOD was based on the Sewage Testing Method (issued by the Japan Sewage Works Association, Sewage Testing Method). Organic nitrogen was calculated by subtracting the measured value of ammonia nitrogen from the measured value of Kjeldahl nitrogen. The method for measuring Kjeldahl nitrogen and ammonia nitrogen was based on the Sewage Testing Method.

[0126] The physical properties of the cationic organic polymer flocculant used in the test are shown in Table 3. Oil separating agent a was used as the cationic organic polymer flocculant. Oil separating agent a (polyacrylic acid ester type, molecular weight 9 million, rotational viscosity 372 mPa s, cationic degree 85 mol%) was dissolved in pure water and used at a dissolved concentration of 20 g / L.

[0127] [Table 3]

[0128] <Test procedure> -Basic procedure- (1) Wastewater was placed in a beaker and the pH was adjusted with a sulfuric acid solution or a sodium hydroxide solution. (2) After adjusting the pH, a cationic organic polymer flocculant (hereinafter, oil separation agent a) was added in small amounts to the wastewater and stirred with a spatula to generate flocs. (3) The state of the reactive flocs and the appearance of the bottom water (hereinafter referred to as treated water) were visually confirmed to determine the appropriate dosage of chemicals and pH. (4) The quality of the treated water was measured using the appropriate amount of chemicals. The concentrated reaction flocs (concentrated sludge) were dehydrated by pressing the reaction flocs on the sieve with a pressure plate. (5) The dewatered flocs (= thickened sludge) were dried (105°C, overnight) and the moisture content was measured.

[0129] -Procedure when using an acid denaturation treatment process- In the acid denaturation treatment, the wastewater was denatured by adjusting it to the acidic side (pH 2-4) using hydrochloric acid or sulfuric acid as step (1), and stirred with a magnetic stirrer for about 10 minutes until the water surface was slightly rippling. Next, an alkaline agent was added to neutralize the wastewater to near neutral (pH 6-7), and the test was carried out according to steps (2) to (4) above.

[0130] -Procedure when using a denaturing treatment process using a surfactant- In examining the surfactant dosage, 0 mg / L, 100 mg / L, 150 mg / L, and 200 mg / L of sodium dodecyl sulfate (hereinafter, SDS) was added to the wastewater, and the pH was adjusted to 5 as in procedure (1), and then tests were conducted according to procedures (2) to (4) above. In addition, in order to examine the effect of the surfactant-based denaturation treatment process and the pH of the water to be treated, the pH of the wastewater was adjusted to 5, 5.5, 6, 7, and 8 using hydrochloric acid, sulfuric acid, and sodium hydroxide in the pH adjustment procedure in (1) above, and 150 mg / L of SDS was added, and then tests were conducted according to procedures (2) to (4) above.

[0131] -Procedure for using a heat treatment denaturation process- Wastewater (250 mL or 500 mL) was placed in a beaker and immersed for 30 minutes to 1 hour in thermostatic baths with heating temperatures of 20 to 25° C. (no heating), 50° C., 55° C., and 60° C. After the wastewater was returned to room temperature, tests were carried out according to the above procedures (2) to (4).

[0132] -Procedure for using alkaline denaturation treatment process- In the study of pH adjustment by alkaline treatment, the pH of the wastewater was adjusted to each of the conditions of 5, 6.3, 7, 8, 9, and 10 in step (1), and then tests were carried out in the above steps (2) to (4).

[0133] -Procedure for testing organic nitrogen content and content ratio- For wastewaters E and G, which had an organic nitrogen concentration of less than 120 mg / L and an organic nitrogen / SS ratio of less than 0.1, the pH was adjusted to 7 using an aqueous sodium hydroxide solution in step (1), and tests were conducted in accordance with steps (2) to (4) above.

[0134] <How to determine reactive flocs> The size of the flocs was measured with a ruler. The strength of the flocs was judged based on whether the flocs did not crumble or whether they crumbled and dispersed when pressed with a spatula. When the flocs had a certain degree of floc strength and were not easily crumbled when pressed, they were rated as "floc strength: present." When the flocs had weak floc strength and were easily crumbled and dispersed when pressed, they were rated as "floc strength: weak."

[0135] The adhesion of the flock was evaluated by visually checking whether it adhered to the spatula or the wall of the beaker when pressed with a spatula, and was judged as follows: A: No adhesion B: The adhesiveness is weak and it can be peeled off with light pressure using a spatula. C: It is difficult to distinguish between B and D. D: Strongly sticky and cannot be removed immediately with a spatula

[0136] In addition, the feasibility of mechanical solid-liquid separation was judged by satisfying three criteria: floc size: 1 mm or more, floc strength: strong, and floc adhesion: within the range of A to C.

[0137] <Method of determining the clarity of treated water> The clarity of the treated water was visually confirmed and judged as follows. When it was difficult to judge one of the following criteria, it was judged as "○-◎". In this example, ◎ and ○ were judged as the applicability of this example. ◎: Transparent, low turbidity, high visibility ○: Slightly cloudy but almost transparent, slight turbidity but high degree of transparency △: Compared to the state of the raw water, it can be seen that the turbidity has been gradually removed, but the turbidity is high and the transparency is low. ×: High turbidity and low transparency (similar to raw water)

[0138] Treated water color, hexane extractable substance removal rate, SS removal rate, COD Mn The removal rate and BOD removal rate were evaluated by measuring the quality of the treated water before modification treatment and the quality of the treated water according to the Sewage Testing Method (published by the Japan Sewage Works Association, Sewage Testing Method).

[0139] <Test Results> <Example 1: Study of denaturation treatment when neutralization treatment is performed after acid denaturation treatment> The results of the treatment test are shown in Table 4. As shown in Examples 1-1 to 1-3, when the pH after the modification treatment was set to 2 or 3, the amount of oil separating agent a injected could be reduced, and the state of the reaction flocs was also good. In Examples 1-1 to 1-3, the hexane extractable substance removal rate was 96 to 98% or more, the SS removal rate: 93 to 96%, and the BOD removal rate: 73 to 79%, all of which were high, and it was possible to simultaneously remove oil, SS, and organic matter. No significant differences were confirmed in the amount of chemical injection, the state of the flocs, and the quality of the treated water, regardless of whether the pH after neutralization was 6 or 7. The sludge water content in Examples 1-2 and 1-3 was 86.7% and 85.1%, respectively.

[0140] In Example 1-4, where the pH after the modification treatment is set to 4, the amount of oil separating agent a added is slightly larger, and the COD MnThe removal rate was also slightly lower than in Examples 1-1 to 1-3, and the color was slightly higher, but the state of the reactive flocs and the clarity of the treated water were good. According to Example 1, it was found that the adhesion of the flocs could be reduced and the size and strength of the flocs could be improved by adding an acidic condition, more specifically, a pH of 5 or less, or even less than pH 4, or even a pH of 2 to 3, through the modification treatment, and then neutralizing the condition to a neutral condition of pH 6 to 7. This improved the quality of the treated water, and made mechanical solid-liquid separation possible.

[0141] [Table 4]

[0142] <Example 2: When a denaturing treatment step using a surfactant is used> (1) Examination of surfactant injection amount The treatment test results are shown in Table 5. In Comparative Example 2-1, where no modification treatment was performed, the amount of oil separating agent a injected was small and the state of the reactive flocs was relatively good, but the clarity of the treated water showed almost no change and good results were not obtained. As shown in Examples 2-1 to 2-3, the amount of oil separating agent a injected increased with an increase in the amount of SDS injected. However, the state of the flocs improved with the increase in the amount of SDS injected. The clarity of the treated water improved with an increase in the amount of SDS injected, but no extreme change in each removal rate was confirmed with an increase in the injection amount. According to Example 2, 、p After adjusting H to the acidic side, SDS It can be seen that adding about 100 to 200 mg / L, and further about 120 to 170 mg / L, improves the quality of the treated water while creating a floc state that allows solid-liquid separation.

[0143] [Table 5]

[0144] (2) Effect of pH adjustment The results of the treatment test are shown in Table 6. As the adjusted pH value increased, the amount of oil separating agent a injected increased. In Examples 2-4, 2-5, and 2-6, under conditions of adjusted pH values ​​of 5 to 6, the state of the flocs did not change, and no significant change in the quality of the treated water was observed. In Example 2-7, when the adjusted pH was 7, the state of the flocs, the SS removal rate, and the COD Mn The removal rate and BOD removal rate were not different from those of Examples 2-4 to 2-6, but the color increased. In Comparative Example 2-2, in which the adjusted pH value was 8, flocs were not generated well, and the clarity of the treated water also deteriorated. From the above results, it was confirmed that in the denaturation treatment by adding a surfactant, it is preferable to add SDS after adjusting the pH to a weak acidic condition of 5 to 7, or even 5 to 6.

[0145] [Table 6]

[0146] <Example 3: When a denaturing treatment step by heat treatment is used> The results of the treatment test are shown in Table 7. As the heating temperature increased, the color of the treated water decreased and the COD Mn The removal rate was improved. In Comparative Examples 3-1 and 3-2, in which no modification treatment by heating was performed, the size of the reactive flocs was insufficient or the strength was inferior, making efficient treatment by mechanical solid-liquid separation difficult, and the clarity was also inferior to that of Examples 3-1 to 3-3. Comparing Example 3-1 and Example 3-2, the amount of oil separating agent a injected, the state of the flocs, and the clarity of the treated water were about the same. However, the chromaticity of the treated water was greatly improved in Example 3-2. In addition, although the amount of oil separating agent a injected in Example 3-3 was slightly increased, the adhesion of the flocs was improved compared to Example 3-2, and there was a decrease in the chromaticity of the treated water and a decrease in COD Mn From the above results, it was confirmed that the heat denaturation treatment at a heating temperature of 50°C or higher, more preferably 55°C or higher, improves the quality of the treated water while forming flocs that can be separated into solid and liquid.

[0147] [Table 7]

[0148] <Example 4: When a denaturing treatment step using alkali treatment is used> In Comparative Examples 4-1 to 4-5, as the pH increased, the clarity of the treated water improved, but the amount of oil separating agent a injected increased, and the tendency for the stickiness of the reactive flocs to increase was confirmed. In particular, when the pH was set to 8 or 9, it could not be said that the modification treatment for imparting the floc strength required for solid-liquid separation to the flocs obtained in the flocculation process was properly performed, and a very sticky thread-like product was generated, making solid-liquid separation impossible. On the other hand, in Example 4-1, although the amount of oil separating agent a injected was large, the stickiness of the flocs was reduced, and the clarity of the treated water was good. According to this Example 4, the condition under which the state of the flocs and the clarity of the treated water were all good by pH adjustment alone was only the condition of pH 10. Therefore, it was confirmed that by adjusting the pH of the water to be treated to 10 by adding an alkaline agent and adding an oil separating agent a, reactive flocs could be well formed, efficient treatment by mechanical solid-liquid separation was also possible, and good results were obtained for the quality of the treated water.

[0149] [Table 8]

[0150] <Example 5: Impact of conventional oil-containing wastewater treatment> The results of the treatment test are shown in Table 9. The reactive flocs in Examples 5-1 and 5-2 had good floc shapes and little floc adhesion under near-neutral conditions. The clarity of the treated water was good, and the hexane extractable substance removal rate was high at 98% or more. From the above results, it was confirmed that good treatment is possible by using the oil separating agent a according to this embodiment for normal oil-containing wastewater with an organic nitrogen / SS ratio of less than 0.1. It is considered that treated water with even better water quality can be obtained by further carrying out the organic nitrogen modification treatment according to this embodiment according to the required water quality of the treated water.

[0151] [Table 9] [Explanation of symbols]

[0152] 1: Denaturation treatment method 1a: Acid treatment means 1b: Neutralization means 1c: Surfactant treatment means 1d: Heat treatment means 1e: Alkaline treatment means 2: Flocculation method 3: Solid-liquid separation means 4: Acquisition method 5: Control means 6: Network 7: Prediction methods 11: Flocculation tank 11a, 12a, 14a, 16a, 18a, 21a: Stirring device 12: Acid treatment tank 13: Acid storage tank 14: Neutralization tank 15: Alkaline agent storage tank 16: Surfactant treatment tank 17: Surfactant reservoir 18: Heat treatment tank 19: Heat treatment equipment 21: Flocculation tank 22:Dissolution tank 31:Solid-liquid separator 32: Belt drive means 33: Inlet 34: Capture means 35: Flock Transportation 36: Belt 37: Belt cleaning means 39: Outlet 41: Pressurizing means 42: Pressure plate 111: Alkaline treatment tank 111a: Stirring device 112: Alkaline agent storage tank

Claims

1. a flocculation step of adding a cationic organic polymer flocculant to the water to be treated, which contains oil, organic nitrogen, and SS, to form flocs; a solid-liquid separation step of subjecting the water to be treated in which the flocs have been formed to solid-liquid separation to obtain treated water; a denaturing treatment step in which the water to be treated is denatured before the flocculation step so that at least the flocs formed in the flocculation step have a floc strength required for the solid-liquid separation and the treated water obtained by the solid-liquid separation has clarity; having The wastewater treatment method, wherein the denaturation treatment step includes a surfactant addition step of adding 50 to 300 mg / L of a surfactant to the neutral or acidic water to be treated.

2. A flocculation process in which a cationic organic polymer flocculant is added to treated water containing oil, organic nitrogen, and SS, and the weight ratio of organic nitrogen to SS when converted to nitrogen (organic nitrogen / SS) is 0.1 to 3, thereby forming flocs; a solid-liquid separation step of subjecting the water to be treated in which the flocs have been formed to solid-liquid separation by a mechanical solid-liquid separation means to obtain treated water; a modification treatment step of performing a modification treatment on the water to be treated prior to the flocculation step so that at least the flocs formed in the flocculation step have a floc strength required for the solid-liquid separation and the treated water obtained by the solid-liquid separation has clarity; having The denaturing treatment step includes: an acid treatment step of adding an acid to the water to be treated so that the pH of the water to be treated is 2 to 3; a neutralization step of adding an alkaline agent to the water to be treated after the acid treatment step to neutralize the water to have a pH of 6 to 7; A wastewater treatment method comprising the steps of:

3. A flocculation process in which a cationic organic polymer flocculant is added to treated water containing oil, organic nitrogen, and SS, and the weight ratio of organic nitrogen to SS when converted to nitrogen (organic nitrogen / SS) is 0.1 to 3, inclusive, to form flocs; a solid-liquid separation step of subjecting the water to be treated in which the flocs have been formed to solid-liquid separation by a mechanical solid-liquid separation means to obtain treated water; a denaturing treatment step in which the water to be treated is denatured before the flocculation step so that at least the flocs formed in the flocculation step have a floc strength required for the solid-liquid separation and the treated water obtained by the solid-liquid separation has clarity; having The wastewater treatment method, wherein the denaturing treatment step includes an alkaline treatment step of adding an alkaline agent to the water to be treated to make the water to be treated alkaline to a pH of 10 or higher.

4. A wastewater treatment method as described in claim 2 or 3, characterized in that a surfactant is added to the treated water in the denaturing treatment process.

5. 2. The wastewater treatment method according to claim 1, wherein the weight ratio of organic nitrogen to SS (organic nitrogen / SS) in terms of nitrogen in the water to be treated is 0.1 or more and 3 or less.

6. 5. The wastewater treatment method according to claim 1, wherein the cationic organic polymer flocculant has a molecular weight of 5,000,000 or more and a cationic degree of 50 mol % or more.

7. 7. The wastewater treatment method according to claim 1, wherein the denaturing treatment step includes a heat treatment step of heating the water to a temperature of 50° C. or higher.

8. a flocculation means including a flocculation tank for adding a cationic organic polymer flocculant to the water to be treated, the cationic organic polymer flocculant being added ... cationic organic polymer flocculant to form flocs; a solid-liquid separation means for performing solid-liquid separation of the water to be treated in which the flocs have formed, to obtain treated water; a modification treatment means for performing a modification treatment on the water to be treated before flowing into the flocculation means so that at least the flocs formed in the flocculation tank have a floc strength required for the solid-liquid separation and the treated water obtained by the solid-liquid separation means has clarity; a surfactant adding means for adding a surfactant to the water to be treated at 50 to 300 mg / L for the purpose of the denaturing treatment of the water to be treated; A wastewater treatment device comprising:

9. an acquiring means for acquiring water quality information or image information of the water to be treated in the flocculation tank; a prediction means for predicting the water quality of the water to be treated in the flocculation tank based on the water quality information or the image information acquired by the acquisition means; and a control means for controlling the injection amount of the cationic organic polymer flocculant based on the prediction result of the prediction means; The wastewater treatment device according to claim 8, further comprising:

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