WO2024075518A1 - Method for decolorizing industrial waste liquid - Google Patents

Method for decolorizing industrial waste liquid Download PDF

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WO2024075518A1
WO2024075518A1 PCT/JP2023/033958 JP2023033958W WO2024075518A1 WO 2024075518 A1 WO2024075518 A1 WO 2024075518A1 JP 2023033958 W JP2023033958 W JP 2023033958W WO 2024075518 A1 WO2024075518 A1 WO 2024075518A1
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supernatant
cationic polymer
liquid
industrial wastewater
wastewater
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PCT/JP2023/033958
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French (fr)
Japanese (ja)
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哲也 足立
順治 中野
正男 中野
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中国環境株式会社
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
    • B01D21/01—Separation of suspended solid particles from liquids by sedimentation using flocculating agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56—Macromolecular compounds

Definitions

  • the present invention relates to a method for decolorizing industrial wastewater such as livestock wastewater, food factory wastewater, dye factory wastewater, etc. More specifically, the present invention relates to a method for decolorizing industrial wastewater that is useful for decolorizing highly colored wastewater such as coffee wastewater.
  • decolorization techniques include biological treatment (biological treatment), ozone ( O3 ) treatment, sodium hypochlorite treatment, electrolysis, and precipitation treatment by adding a coagulant.
  • biological treatment may not be effective enough in reducing color
  • ozone treatment and electrolysis require a large initial investment to achieve a sufficient color reduction effect.
  • sodium hypochlorite treatment has a high decolorization effect, but it has high running costs, has a negative effect on activated sludge treatment, and also contaminates the treated water with chlorine, which has a negative effect on fish in rivers and the like.
  • Patent Document 1 a method for decolorization of livestock wastewater (Patent Document 1) is known, which includes adding an iron-based flocculant to livestock wastewater, flocculating suspended matter and coagulating soluble coloring matter to perform primary decolorization treatment, treating the treated liquid with a solid-liquid separation method such as sedimentation separation or filtration to make it clear, and then performing secondary decolorization treatment with ultraviolet light including natural light or ultraviolet light and a photocatalyst.
  • Patent Document 1 includes adding an iron-based flocculant to livestock wastewater, flocculating suspended matter and coagulating soluble coloring matter to perform primary decolorization treatment, treating the treated liquid with a solid-liquid separation method such as sedimentation separation or filtration to make it clear, and then performing secondary decolorization treatment with ultraviolet light including natural light or ultraviolet light and a photocatalyst.
  • a water treatment method (Patent Document 2) is characterized in that three types of chemicals, at least one of soluble aluminum salts or soluble iron salts, an arbitrary amount of alkali metal carbonate, and an arbitrary amount of a reaction moderator, are administered to the liquid to be treated and stirred at approximately the same time to flocculate, decolorize, and/or desalt suspended matter in the treated liquid.
  • a method for treating a dye- or pigment-containing liquid (Patent Document 3) is known, which includes adding a treatment agent containing one or more inorganic flocculants or polymer flocculants to the dye- or pigment-containing liquid.
  • any of these methods adequately balances the cost of the decolorization treatment with the decolorization effect, and it is necessary to find a better method.
  • the Ministry of the Environment has set a uniform discharge standard for the phosphorus content of wastewater discharged into the environment at 16 mg/L (daily average 8 mg/L) or less in order to prevent eutrophication of lakes, ponds, and coastal seas.
  • a livestock wastewater treatment device which comprises a pretreatment tank which mainly performs solid-liquid separation, a first digestion tank which mainly performs acidic fermentation and alkaline fermentation, a second digestion tank which also performs acidic fermentation and alkaline fermentation and has a contact material installed inside, a digestion filter tank which decomposes nitrate nitrogen with anaerobic bacteria and removes suspended matter and particles, and a soil treatment tank which has an infiltrative member buried in breathable soil, arranged in this order, and which is characterized by having a floating impeller installed in the second digestion tank (Patent Document 4).
  • biological treatments such as acid fermentation and alkaline fermentation require frequent maintenance to adjust to optimal treatment conditions.
  • JP 2010-201279 A Japanese Patent Application Laid-Open No. 2-099185 Japanese Patent Application Laid-Open No. 11-276809 JP 2002-45885 A
  • the objective of the present invention is to provide a method for efficiently decolorizing colored industrial wastewater.
  • the inventors discovered that the coloring of the first supernatant liquid obtained by mixing an iron-based inorganic flocculant and a cationic polymer flocculant and then performing solid-liquid separation can be significantly reduced by adjusting the pH of the first supernatant liquid to a predetermined range and then adding an iron-based inorganic flocculant and a cationic polymer flocculant again, and thus completed the present invention.
  • the gist of the present invention is [1] A method for decolorizing industrial wastewater, comprising the steps of: a first precipitation treatment step in which an iron-based inorganic flocculant and a cationic polymer flocculant are mixed with the industrial wastewater, followed by solid-liquid separation to extract a first supernatant liquid; an alkali treatment step of mixing an alkaline agent with the first supernatant to adjust the pH of the first supernatant to 8 or more; a second precipitation treatment step of mixing an iron-based inorganic flocculant with the pH-adjusted first supernatant, then mixing an alkaline agent to adjust the pH to 6 or more, then mixing a cationic polymer flocculant therewith, and subjecting the mixture to solid-liquid separation to extract a second supernatant, said second precipitation treatment step comprising the steps of: [2] The method for decolorizing industrial wastewater according to [1], wherein the iron-based inorganic flocculant is ferrous chloride, ferr
  • the present invention makes it possible to efficiently decolorize industrial wastewater such as livestock wastewater, food factory wastewater, and dye factory wastewater.
  • the present invention can reduce impurities, such as phosphorus, in the industrial wastewater, so that even if the decolorized industrial wastewater is discharged into the environment, the impact on the environment can be significantly reduced.
  • the method for decolorizing industrial wastewater comprises the steps of: a first precipitation treatment step in which an iron-based inorganic flocculant and a cationic polymer flocculant are mixed with the industrial wastewater, followed by solid-liquid separation to extract a first supernatant liquid; an alkali treatment step of mixing an alkaline agent with the first supernatant to adjust the pH of the first supernatant to 8 or more;
  • the method is characterized by having a second precipitation treatment step in which an iron-based inorganic flocculant is mixed with the pH-adjusted first supernatant liquid, an alkaline agent is then added to adjust the pH to 6 or more, a cationic polymer flocculant is then added, and a second supernatant liquid is taken out by solid-liquid separation.
  • the industrial waste liquid refers to colored waste liquid discharged from industrial sites such as livestock farms, food factories, dye factories, etc.
  • Livestock wastewater refers to wastewater containing excrement and the wastewater from washing it, discharged from livestock farms that breed, raise or fatten livestock such as cows, pigs, horses, sheep, and goats, and poultry such as chickens, ducks, and quails.
  • Food factory wastewater refers to wastewater discharged during the food manufacturing process in various food factories, including beverages, dairy products, confectioneries, grain products, sweeteners, spices, brewed foods, fresh foods, meat products, and fish and marine products.
  • Dye factory effluent refers to effluent discharged from dye factories.
  • the industrial wastewater contains various impurities such as organic and inorganic substances, and it is generally required to reduce the concentration of impurities in the industrial wastewater to a predetermined value by precipitation treatment or the like before discharging the industrial wastewater into the environment.
  • the industrial waste liquid used in the present invention includes not only colored raw waste liquid, but also colored waste liquid that has been treated to reduce the concentration of impurities, and colored waste liquid obtained by concentrating and dehydrating sludge separated from raw waste liquid.
  • the degree of color of the industrial wastewater may be, for example, 600 degrees or more when measured based on the transmitted light measurement method in Section 2, Chapter 2, Section 4, Paragraph 2 of the Sewage Testing Methods.
  • This step is a step for precipitating and removing impurities such as organic matter and inorganic matter in the industrial wastewater using an iron-based inorganic flocculant and a cationic polymer flocculant, and recovering a first supernatant liquid.
  • the iron-based inorganic flocculants include ferrous chloride, ferric chloride, polyferric sulfate, etc.
  • the iron-based inorganic flocculants may be used alone or in combination of two or more kinds.
  • the amount of the iron-based inorganic coagulant to be mixed with the industrial wastewater may be appropriately determined depending on the type of industrial wastewater to be treated, and is not particularly limited. From the viewpoint of high impurity removal effect, the amount is preferably 100 mg/L or more, more preferably 300 mg/L or more, and even more preferably 500 mg/L or more. From the viewpoint of excellent economy, the amount is preferably 10,000 mg/L or less, more preferably 5,000 mg/L or less, and even more preferably 2,000 mg/L or less.
  • the cationic polymer flocculant is used to make the flocculants formed by using the iron-based inorganic flocculant larger and to facilitate precipitation.
  • the cationic polymer flocculant may be an acrylic or methacrylic cationic polymer flocculant.
  • the acrylic polymer flocculant include Mannich modified polyacrylamide.
  • the methacrylic polymer flocculant include homopolymers of cationic methacrylic acid ester compounds, quaternary salts thereof, and copolymers of acrylamide and cationic methacrylic acid ester compounds.
  • the cationic polymer flocculants may be used alone or in combination of two or more kinds.
  • the amount of the cationic polymer flocculant to be mixed with the industrial wastewater may be appropriately determined depending on the type of industrial wastewater to be treated, the type of iron-based inorganic flocculant to be used in combination, etc., and is not particularly limited. From the viewpoint of high impurity removal effect, it is preferably 10 mg/L or more, and more preferably 20 mg/L or more, and from the viewpoint of excellent economy, it is preferably 200 mg/L or less, and more preferably 100 mg/L or less.
  • the method of solid-liquid separation in this process may be any method commonly used for industrial wastewater, and is not particularly limited, but examples include coagulation sedimentation, filtration, centrifugation, squeezing, membrane separation, etc.
  • the first supernatant contains dissolved iron-based inorganic flocculants and cationic polymer flocculants, so its pH is adjusted to 5 or less, making it an acidic solution.
  • the first supernatant liquid has fewer impurities than the industrial wastewater used as the raw material for treatment, making it a colored liquid with reduced chromaticity.
  • Alkaline treatment step This step is a step of adjusting the pH of the first supernatant to 8 or more using an alkaline agent. By carrying out the alkaline treatment and the subsequent second precipitation treatment in this manner, it is possible to facilitate aggregation of the colored components in the first supernatant.
  • the alkaline agent is not particularly limited, but examples thereof include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and the like.
  • the type and amount of the alkaline agent are not particularly limited as long as they can adjust the pH of the first supernatant to 8 or higher.
  • This process is a process in which an iron-based inorganic flocculant is mixed with the first supernatant liquid adjusted to alkaline as described above, then an alkaline agent is added to adjust the pH to 6 or more, and then a cationic polymer flocculant is added, followed by solid-liquid separation to extract a second supernatant liquid.
  • the iron-based inorganic flocculant used in this step may be any one that can be used in the first precipitation treatment step.
  • the type of iron-based inorganic flocculant used in this step may be the same as or different from that used in the first precipitation treatment step.
  • the amount of the iron-based inorganic flocculant to be mixed with the first supernatant may be appropriately determined depending on the type of industrial wastewater to be treated, and is not particularly limited. From the viewpoint of high effectiveness in removing colored components, the amount is preferably 100 mg/L or more, and more preferably 300 mg/L or more. From the viewpoint of excellent economy, the amount is preferably 10,000 mg/L or less, more preferably 5,000 mg/L or less, and even more preferably 2,000 mg/L or less.
  • the pH of the first supernatant to which the iron-based inorganic flocculant has been added is preferably adjusted to an acidic pH of 5 or less.
  • an alkaline agent is added to the first supernatant.
  • the pH of the first supernatant liquid which has been reduced by adding an iron-based inorganic flocculant, is raised again by adding an alkaline agent, which has the effect of making it easier to precipitate the colored components when a cationic polymer flocculant is added.
  • the alkaline agent used in this step may be any agent that can be used in the alkaline treatment step.
  • the type of alkaline agent used in this step may be the same as or different from that used in the alkaline treatment step.
  • the type and amount of the alkaline agent should be sufficient to adjust the pH of the first supernatant to 6 or higher.
  • the cationic polymer flocculant used in this step may be any one that can be used in the first precipitation treatment step.
  • the type of cationic polymer flocculant used in this step may be the same as or different from that used in the first precipitation treatment step.
  • the amount of the cationic polymer flocculant to be mixed with the first supernatant may be appropriately determined depending on the type of industrial wastewater to be treated, the type of iron-based inorganic flocculant to be used in combination, etc., and is not particularly limited. From the viewpoint of high effectiveness in removing colored components, the amount is preferably 10 mg/L or more, and more preferably 20 mg/L or more, and from the viewpoint of excellent economy, the amount is preferably 200 mg/L or less, and more preferably 100 mg/L or less.
  • the method of solid-liquid separation in this step is not particularly limited as long as it is a method that can be used in the first precipitation treatment step.
  • the second supernatant liquid obtained in this process is a liquid in which the degree of coloration has been significantly reduced; for example, when measuring the chromaticity, it is possible to reduce the chromaticity of even coffee waste liquid to less than 140 degrees.
  • the second supernatant liquid is a liquid that can be discharged into the environment more safely because the content of coloring components has been significantly reduced in addition to impurities.
  • the stirring conditions may be performed at room temperature, and there are no particular limitations on the stirring speed, etc.
  • the solid matter separated by the method of the present invention can be disposed of according to conventional methods.
  • the method of the present invention has the advantages of being simple and economical in that the coloring components can be significantly reduced from industrial wastewater by repeatedly performing solid-liquid separation using an iron-based inorganic flocculant and a cationic polymer flocculant while adjusting the pH conditions, without using other treatments such as biological treatment. Furthermore, the method of the present invention can reduce impurities in the industrial wastewater, such as phosphorus, in addition to the coloring components, so that even if the decolorized treatment liquid is discharged into the environment, the impact on the environment can be significantly reduced.
  • Example 1 Method for decolorizing livestock wastewater
  • effluent obtained by treating livestock wastewater with activated sludge was used as raw water.
  • the raw water was a brown liquid with a pH of 7.1 (color index: 850 degrees).
  • the degree of light yellow to yellowish brown color of the sample was measured by absorptiometry using a spectrophotometer (Shimadzu Corporation, UV-1800) based on the transmitted light measurement method described in Section 4, Chapter 2, Part 2 of the Sewage Testing Methods.
  • the absorbance at around 390 nm was measured.
  • the chromaticity was measured according to the following procedure. (Test method) The sample is filtered through filter paper type 5C or a filter material with a pore size of 1 ⁇ m or less, or centrifuged at about 3,000 rpm for 20 minutes to remove turbidity.
  • a portion of 100 ml of this sample is placed in an absorption cell (path length 50 nm) and the absorbance at a wavelength of about 390 nm is measured using a spectrophotometer. If the color of the sample is 100 degrees or more, take an appropriate amount of the sample and add water to make it 100 ml. (Creating a calibration curve) Put 1.0 to 100 ml of the color standard solution (100 degrees) into several 100 ml volumetric flasks in stages and add water up to the mark. Then, measure the absorbance in the same manner as in the test procedure, and obtain the relationship between color and absorbance. The quantification range of this method is 0 to 100 degrees, with the minimum unit being 1 degree.
  • Ferric chloride was added to the raw water so as to give a concentration of 536 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 3.0).
  • a cationic polymer flocculant cationic polyacrylamide
  • a concentration of 40 mg/L was added to the solution to give a concentration of 40 mg/L, and the solution was stirred at 250 rpm for 5 minutes.
  • solid-liquid separation was performed using filter paper to obtain a first supernatant liquid (pH 3.0, light brown). The first supernatant was adjusted to pH 10.0 by adding an aqueous solution of sodium hydroxide.
  • ferric chloride was added to the first supernatant to a concentration of 322 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 3.3).
  • an aqueous solution of sodium hydroxide was added to the first supernatant to adjust the pH to 6.7, and the mixture was stirred at 500 rpm for 5 minutes.
  • a cationic polymer flocculant (cationic polyacrylamide) was added to the first supernatant to a concentration of 80 mg/L, and the mixture was stirred at 250 rpm for 5 minutes.
  • solid-liquid separation was performed using filter paper to obtain a second supernatant liquid (pH 6.7, light brown, color degree 75 degrees).
  • the obtained second supernatant liquid had a pH adjusted to approximately neutral and a significantly lower color than the raw water, and could be safely discharged into the environment as is without dilution.
  • the decolorization of the waste liquid as described above can be achieved in a short time, and therefore the decolorization effect is excellent.
  • the decolorization can be carried out by simply adding an iron-based inorganic flocculant and a cationic polymer flocculant, no other special equipment is required, and therefore the decolorization method is simple and has excellent practicality.
  • Example 2 Method for decolorizing wastewater (raw water) from a coffee factory)
  • the raw water used for the food processing plant was wastewater discharged from a coffee factory.
  • the raw water was a black liquid with a pH of 5.8 (color degree 3400 degrees).
  • Ferric chloride was added to the raw water so as to give a concentration of 536 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 4.5).
  • a cationic polymer flocculant (cationic polyacrylamide) was added to the solution so as to give a concentration of 40 mg/L, and the solution was stirred at 250 rpm for 5 minutes.
  • solid-liquid separation was performed using filter paper to obtain a first supernatant liquid (pH 4.5, pale green).
  • an aqueous solution of sodium hydroxide was added to the first supernatant to adjust the pH to 8.4.
  • ferric chloride was added to the first supernatant to a concentration of 322 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 6.0).
  • an aqueous solution of sodium hydroxide was added to the first supernatant to adjust the pH to 7.0.
  • a cationic polymer flocculant (cationic polyacrylamide) was added to the first supernatant to give a concentration of 40 mg/L, and the mixture was stirred at 250 rpm for 5 minutes.
  • solid-liquid separation was performed using filter paper to obtain a second supernatant liquid (pH 7.0, light brown, color degree 130 degrees).
  • the obtained second supernatant liquid had a pH adjusted to near neutral and a significantly lower color value of less than 140 compared to the raw water, and could be safely discharged into the environment as is without dilution.
  • the decolorization of the waste liquid as described above can be achieved in a short time, and therefore the decolorization effect is excellent.
  • the decolorization can be carried out by simply adding an iron-based inorganic flocculant and a cationic polymer flocculant, no other special equipment is required, and therefore the decolorization method is simple and has excellent practicality.
  • Example 3 Method for decolorizing livestock wastewater
  • the colored wastewater discharged from a cowshed was subjected to a general biological treatment, and the raw water was subjected to a decolorization treatment in the same manner as in Example 1.
  • the color and TP (total phosphorus) of the raw water (pH 8.61) and the decolorized water (pH 5.85) are shown in Table 1.
  • the amount of phosphorus was measured as the total phosphorus concentration (T-P) using the potassium peroxodisulfate decomposition method described in the phosphorus measurement method "JIS K 0102-46.3.1.”

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Abstract

Provided is a method for decolorizing an industrial waste liquid, said method comprising: a first precipitation treatment step for mixing an iron-based inorganic flocculant and a cationic polymer flocculant into an industrial waste liquid and performing solid-liquid separation to extract a first supernatant liquid; an alkali treatment step for mixing an alkaline agent into the first supernatant liquid to adjust the pH of the first supernatant liquid to 8 or higher; and a second precipitation treatment step for mixing an iron-based inorganic flocculant into the pH-adjusted first supernatant liquid, then mixing an alkaline agent to adjust the pH to 6 or higher, then mixing a cationic polymer flocculant, and performing solid-liquid separation to extract a second supernatant liquid.

Description

産業廃液の脱色方法Method for decolorizing industrial wastewater
　本発明は、畜産廃液、食品工場廃液、染色工場廃液等の産業廃液の脱色方法に関する。さらに詳しくは、コーヒー廃水等の濃厚な着色廃液を脱色するうえで有用な産業排水の脱色方法に関する。 The present invention relates to a method for decolorizing industrial wastewater such as livestock wastewater, food factory wastewater, dye factory wastewater, etc. More specifically, the present invention relates to a method for decolorizing industrial wastewater that is useful for decolorizing highly colored wastewater such as coffee wastewater.
　家畜の畜産場から出る畜産廃液、食品工場や染色工場からの産業廃液は、いずれも有機物を含む環境負荷の大きい廃液であり、所定の不純物の除去処理をした後、その処理液を河川等の環境中へ排出するようになっている。 Livestock wastewater from livestock farms and industrial wastewater from food factories and dye factories both contain organic matter and pose a large environmental burden. After undergoing treatment to remove certain impurities, the treated liquid is discharged into the environment, such as rivers.
　前記産業廃液は、環境中で問題のない程度に不純物が除去されているものの、着色しているケースが多いため、そのまま環境中に排出されると、住民から苦情等が出てくるケースが多いため、脱色処理を行う必要があった。 Although impurities have been removed from the industrial wastewater to a level that is not problematic for the environment, it is often discolored. If it is discharged directly into the environment, this can lead to complaints from residents, and so it is necessary to carry out a decolorization process.
　脱色処理技術としては、従来、生物学的処理（生物処理）、オゾン（Ｏ3）処理、次亜塩素酸ソーダ処理、電気分解、凝集剤添加による沈殿処理等が知られている。ここで、生物学的処理は、色度低減効果が不十分な場合があり、オゾン処理や電気分解は、十分な色度低減効果を得るためには初期投資額が大きい。また、次亜塩素酸ソーダ処理は、脱色効果は高いものの、ランニングコストが高く、活性汚泥処理に悪影響を及し、また、処理水に塩素が混入し、河川等の魚類等に悪影響を及ぼす。 Conventionally, known decolorization techniques include biological treatment (biological treatment), ozone ( O3 ) treatment, sodium hypochlorite treatment, electrolysis, and precipitation treatment by adding a coagulant. Here, biological treatment may not be effective enough in reducing color, and ozone treatment and electrolysis require a large initial investment to achieve a sufficient color reduction effect. Moreover, sodium hypochlorite treatment has a high decolorization effect, but it has high running costs, has a negative effect on activated sludge treatment, and also contaminates the treated water with chlorine, which has a negative effect on fish in rivers and the like.
　一方、凝集剤添加による沈殿処理は、問題が少なく、脱色処理に一般的に使用されている。例えば、畜産系廃液に鉄系凝集剤を添加し、懸濁物質の凝集及び溶解性の着色物質の凝析を行って一次脱色処理を行い、該処理液を沈降分離や濾過等の固液分離法で処理して清澄になったものを、自然光を含む紫外線又は紫外線と光触媒によって二次脱色処理することを含む畜産系廃液の脱色方法（特許文献１）、可溶性のアルミニウム塩又は可溶性の鉄塩の中の少なくとも一種、任意量のアルカリ金属の炭酸塩、任意量の反応緩和剤の３種の薬剤を略同時に被処理液に投与して撹拌し、処理液中の浮遊物の凝集、脱色及び（又は）脱塩を行うことを特徴とする水処理方法（特許文献２）、染料又は顔料含有液に無機系凝集剤又は高分子凝集剤の１種又は２種以上を含有する処理剤を添加する染料又は顔料含有液の処理方法（特許文献３）等が知られている。
　しかしながら、いずれも脱色処理にかかるコストと脱色効果のバランスが十分にとれているとは言い難く、より優れた方法を検討する必要であった。 On the other hand, precipitation treatment by adding a flocculant is less problematic and is generally used for decolorization treatment. For example, a method for decolorization of livestock wastewater (Patent Document 1) is known, which includes adding an iron-based flocculant to livestock wastewater, flocculating suspended matter and coagulating soluble coloring matter to perform primary decolorization treatment, treating the treated liquid with a solid-liquid separation method such as sedimentation separation or filtration to make it clear, and then performing secondary decolorization treatment with ultraviolet light including natural light or ultraviolet light and a photocatalyst. A water treatment method (Patent Document 2) is characterized in that three types of chemicals, at least one of soluble aluminum salts or soluble iron salts, an arbitrary amount of alkali metal carbonate, and an arbitrary amount of a reaction moderator, are administered to the liquid to be treated and stirred at approximately the same time to flocculate, decolorize, and/or desalt suspended matter in the treated liquid. A method for treating a dye- or pigment-containing liquid (Patent Document 3) is known, which includes adding a treatment agent containing one or more inorganic flocculants or polymer flocculants to the dye- or pigment-containing liquid.
However, it is difficult to say that any of these methods adequately balances the cost of the decolorization treatment with the decolorization effect, and it is necessary to find a better method.
　また、日本では、環境放出される廃液中のリンの含有量について、湖沼や沿岸海域の富栄養化を防止するため、環境省は一律排水基準でリン含有量を１６ｍｇ／Ｌ（日間平均８ｍｇ／Ｌ）以下と定めている。
　そこで、例えば、主として固液分離を行なう前処理槽、主として酸性発酵とアルカリ発酵とを行なう第一消化槽、同じく酸性発酵とアルカリ発酵とを行なう、接触材を内部に設けた第二消化槽、硝酸態窒素を嫌気性菌で分解すると共に、浮遊物、懸濁粒子を除去する、ろ材を充填した消化ろ過槽及び通気性土壌中に浸潤部材を埋設してなる土壌処理槽をこの順に配設し、該第二消化槽内に浮上式羽根車を設けたことを特徴とする畜産排水処理装置が知られている（特許文献４）。
　しかしながら、酸性発酵及びアルカリ発酵等のような生物処理は、最適な処理条件に調整するために、頻繁なメンテナンスが必要になる。 In Japan, the Ministry of the Environment has set a uniform discharge standard for the phosphorus content of wastewater discharged into the environment at 16 mg/L (daily average 8 mg/L) or less in order to prevent eutrophication of lakes, ponds, and coastal seas.
For example, a livestock wastewater treatment device is known which comprises a pretreatment tank which mainly performs solid-liquid separation, a first digestion tank which mainly performs acidic fermentation and alkaline fermentation, a second digestion tank which also performs acidic fermentation and alkaline fermentation and has a contact material installed inside, a digestion filter tank which decomposes nitrate nitrogen with anaerobic bacteria and removes suspended matter and particles, and a soil treatment tank which has an infiltrative member buried in breathable soil, arranged in this order, and which is characterized by having a floating impeller installed in the second digestion tank (Patent Document 4).
However, biological treatments such as acid fermentation and alkaline fermentation require frequent maintenance to adjust to optimal treatment conditions.
特開２０１０－２０１２７９号公報JP 2010-201279 A 特開平２－０９９１８５号公報Japanese Patent Application Laid-Open No. 2-099185 特開平１１－２７６８０９号公報Japanese Patent Application Laid-Open No. 11-276809 特開２００２－４５８８５号公報JP 2002-45885 A
　本発明は、着色されている産業廃液の脱色を効率よく行うことができる方法を提供することを目的とする。 The objective of the present invention is to provide a method for efficiently decolorizing colored industrial wastewater.
　本発明者らは、鉄系無機凝集剤及びカチオン系高分子凝集剤を混合して固液分離した第一上澄み液の着色が、この第一上澄み液のｐＨを所定の範囲に調整した後、再度、鉄系無機凝集剤及びカチオン系高分子凝集剤を添加することで、顕著に低減できることを見出して、本発明を完成させた。 The inventors discovered that the coloring of the first supernatant liquid obtained by mixing an iron-based inorganic flocculant and a cationic polymer flocculant and then performing solid-liquid separation can be significantly reduced by adjusting the pH of the first supernatant liquid to a predetermined range and then adding an iron-based inorganic flocculant and a cationic polymer flocculant again, and thus completed the present invention.
　本発明の要旨は、
［１］産業廃液の脱色方法であって、
　産業廃液に鉄系無機凝集剤及びカチオン系高分子凝集剤を混合し、固液分離して第一上澄み液を取り出す第一沈殿処理工程、
　第一上澄み液にアルカリ剤を混合して第一上澄み液のｐＨを８以上に調整するアルカリ処理工程、
　ｐＨ調整された第一上澄み液に、鉄系無機凝集剤を混合し、次いで、アルカリ剤を混合してｐＨを６以上に調整し、次いで、カチオン系高分子凝集剤を混合し、固液分離して第二上澄み液を取り出す、第二沈殿処理工程
を有することを特徴とする、産業廃液の脱色方法、
［２］前記鉄系無機凝集剤が、塩化第一鉄、塩化第二鉄又はポリ硫酸第二鉄である、前記［１］に記載の産業廃液の脱色方法、
［３］前記カチオン系高分子凝集剤が、アクリル系又はメタクリル系のカチオン性高分子凝集剤である、前記［１］又は［２］に記載の産業廃液の脱色方法、
［４］前記産業廃液が、畜産廃液、食品工場廃液又は染色工場廃液である、前記［１］～［３］のいずれかに記載の産業廃液の脱色方法
に関する。 The gist of the present invention is
[1] A method for decolorizing industrial wastewater, comprising the steps of:
a first precipitation treatment step in which an iron-based inorganic flocculant and a cationic polymer flocculant are mixed with the industrial wastewater, followed by solid-liquid separation to extract a first supernatant liquid;
an alkali treatment step of mixing an alkaline agent with the first supernatant to adjust the pH of the first supernatant to 8 or more;
a second precipitation treatment step of mixing an iron-based inorganic flocculant with the pH-adjusted first supernatant, then mixing an alkaline agent to adjust the pH to 6 or more, then mixing a cationic polymer flocculant therewith, and subjecting the mixture to solid-liquid separation to extract a second supernatant, said second precipitation treatment step comprising the steps of:
[2] The method for decolorizing industrial wastewater according to [1], wherein the iron-based inorganic flocculant is ferrous chloride, ferric chloride or polyferric sulfate.
[3] The method for decolorizing industrial wastewater according to [1] or [2], wherein the cationic polymer flocculant is an acrylic or methacrylic cationic polymer flocculant.
[4] The method for decolorizing industrial wastewater according to any one of [1] to [3] above, wherein the industrial wastewater is livestock wastewater, food factory wastewater, or dye factory wastewater.
　本発明により、畜産廃液、食品工場廃液、染色工場廃液等の産業廃液の着色を効率よく脱色することができる。また、本発明により、前記産業廃液中の不純物、例えば、リンを低減できるため、産業廃液の脱色処理液を環境中に排出しても、環境に対する影響を顕著に低減することができる。 The present invention makes it possible to efficiently decolorize industrial wastewater such as livestock wastewater, food factory wastewater, and dye factory wastewater. In addition, the present invention can reduce impurities, such as phosphorus, in the industrial wastewater, so that even if the decolorized industrial wastewater is discharged into the environment, the impact on the environment can be significantly reduced.
　本発明に係る産業廃液の脱色方法は、
　産業廃液に鉄系無機凝集剤及びカチオン系高分子凝集剤を混合し、固液分離して第一上澄み液を取り出す第一沈殿処理工程、
　第一上澄み液にアルカリ剤を混合して第一上澄み液のｐＨを８以上に調整するアルカリ処理工程、
　ｐＨ調整された第一上澄み液に、鉄系無機凝集剤を混合し、次いで、アルカリ剤を混合してｐＨを６以上に調整し、次いで、カチオン系高分子凝集剤を混合し、固液分離して第二上澄み液を取り出す、第二沈殿処理工程
を有することを特徴とする。 The method for decolorizing industrial wastewater according to the present invention comprises the steps of:
a first precipitation treatment step in which an iron-based inorganic flocculant and a cationic polymer flocculant are mixed with the industrial wastewater, followed by solid-liquid separation to extract a first supernatant liquid;
an alkali treatment step of mixing an alkaline agent with the first supernatant to adjust the pH of the first supernatant to 8 or more;
The method is characterized by having a second precipitation treatment step in which an iron-based inorganic flocculant is mixed with the pH-adjusted first supernatant liquid, an alkaline agent is then added to adjust the pH to 6 or more, a cationic polymer flocculant is then added, and a second supernatant liquid is taken out by solid-liquid separation.
　本発明において、産業廃液とは、畜産、食品工場、染色工場等の産業現場から排出される有色の廃液をいう。
　畜産廃液とは、ウシ、ブタ、ウマ、ヒツジ、ヤギ等の家畜、ニワトリ、アヒル、ウズラ等の家禽を繁殖、飼育又は肥育する畜産場から排出される、排泄物とその洗浄排水等を含む廃液をいう。
　食品工場廃液とは、飲料、乳製品、菓子類、穀物製品、甘味料、香辛料、醸造食品、生鮮食品、食肉製品、魚類・水産製品等、様々な食品工場において食品を製造する過程で排出される廃液をいう。
　染色工場廃液とは、染色工場から排出される廃液をいう。 In the present invention, the industrial waste liquid refers to colored waste liquid discharged from industrial sites such as livestock farms, food factories, dye factories, etc.
Livestock wastewater refers to wastewater containing excrement and the wastewater from washing it, discharged from livestock farms that breed, raise or fatten livestock such as cows, pigs, horses, sheep, and goats, and poultry such as chickens, ducks, and quails.
Food factory wastewater refers to wastewater discharged during the food manufacturing process in various food factories, including beverages, dairy products, confectioneries, grain products, sweeteners, spices, brewed foods, fresh foods, meat products, and fish and marine products.
Dye factory effluent refers to effluent discharged from dye factories.
　前記産業廃液中には、様々な有機物、無機物等の不純物が含まれており、一般には、沈殿処理等により産業廃液中の不純物の濃度を所定値よりも低減したうえで、環境中に排出することが要求されている。
　本発明で使用する産業廃液には、有色の廃液原液だけでなく、不純物濃度が低減処理された有色の廃液、廃液原液から分離された汚泥を濃縮・脱水等して得られる有色の廃液等も含まれる。 The industrial wastewater contains various impurities such as organic and inorganic substances, and it is generally required to reduce the concentration of impurities in the industrial wastewater to a predetermined value by precipitation treatment or the like before discharging the industrial wastewater into the environment.
The industrial waste liquid used in the present invention includes not only colored raw waste liquid, but also colored waste liquid that has been treated to reduce the concentration of impurities, and colored waste liquid obtained by concentrating and dehydrating sludge separated from raw waste liquid.
　前記産業廃液の有色の程度としては、例えば、色度を下水試験方法　２編２章４節２の透過光測定法に基づいて測定した場合に、色度６００度以上のものが挙げられる。 The degree of color of the industrial wastewater may be, for example, 600 degrees or more when measured based on the transmitted light measurement method in Section 2, Chapter 2, Section 4, Paragraph 2 of the Sewage Testing Methods.
（第一沈殿処理工程）
　本工程は、鉄系無機凝集剤及びカチオン系高分子凝集剤を用い、産業廃液中の有機物、無機物等の不純物を沈殿・除去して、第一上澄み液を回収するための工程である。 (First precipitation treatment step)
This step is a step for precipitating and removing impurities such as organic matter and inorganic matter in the industrial wastewater using an iron-based inorganic flocculant and a cationic polymer flocculant, and recovering a first supernatant liquid.
　前記鉄系無機凝集剤としては、塩化第一鉄、塩化第二鉄、ポリ硫酸第二鉄等が挙げられる。本発明では、前記鉄系無機凝集剤は、単独で使用してもよいし、２種以上を組み合わせて用いてもよい。 The iron-based inorganic flocculants include ferrous chloride, ferric chloride, polyferric sulfate, etc. In the present invention, the iron-based inorganic flocculants may be used alone or in combination of two or more kinds.
　前記産業廃液に混合する前記鉄系無機凝集剤の量としては、処理対象の産業廃液の種類に応じて適宜決定すればよく、特に限定はないが、不純物の除去効果が高い観点から、１００ｍｇ／Ｌ以上が好ましく、３００ｍｇ／Ｌ以上がより好ましく、５００ｍｇ／Ｌ以上がさらに好ましく、また、経済性に優れる観点から、１００００ｍｇ／Ｌ以下が好ましく、５０００ｍｇ／Ｌ以下がより好ましく、２０００ｍｇ／Ｌ以下がさらに好ましい。 The amount of the iron-based inorganic coagulant to be mixed with the industrial wastewater may be appropriately determined depending on the type of industrial wastewater to be treated, and is not particularly limited. From the viewpoint of high impurity removal effect, the amount is preferably 100 mg/L or more, more preferably 300 mg/L or more, and even more preferably 500 mg/L or more. From the viewpoint of excellent economy, the amount is preferably 10,000 mg/L or less, more preferably 5,000 mg/L or less, and even more preferably 2,000 mg/L or less.
　前記カチオン系高分子凝集剤は、前記鉄系無機凝集剤を用いることで生じた凝集塊をより大きくして、沈殿させやすくするために使用される。
　前記カチオン系高分子凝集剤としては、アクリル系又はメタクリル系のカチオン性高分子凝集剤等が挙げられる。
　アクリル系高分子凝集剤としては、例えば、ポリアクリルアミドのマンニッヒ変性物等が挙げられる。
　メタクリル系高分子凝集剤としては、カチオン性メタクリル酸エステル化合物のホモポリマー、その四級塩、アクリルアミドとカチオン性メタクリル酸エステル化合物との共重合物等が挙げられる。
　本発明では、前記カチオン系高分子凝集剤は、単独で使用してもよいし、２種以上を組み合わせて用いてもよい。 The cationic polymer flocculant is used to make the flocculants formed by using the iron-based inorganic flocculant larger and to facilitate precipitation.
The cationic polymer flocculant may be an acrylic or methacrylic cationic polymer flocculant.
Examples of the acrylic polymer flocculant include Mannich modified polyacrylamide.
Examples of the methacrylic polymer flocculant include homopolymers of cationic methacrylic acid ester compounds, quaternary salts thereof, and copolymers of acrylamide and cationic methacrylic acid ester compounds.
In the present invention, the cationic polymer flocculants may be used alone or in combination of two or more kinds.
　前記産業廃液に混合する前記カチオン系高分子凝集剤の量としては、処理対象の産業廃液の種類、併用される鉄系無機凝集剤の種類等に応じて適宜決定すればよく、特に限定はないが、不純物の除去効果が高い観点から、１０ｍｇ／Ｌ以上が好ましく、２０ｍｇ／Ｌ以上がより好ましく、また、経済性に優れる観点から、２００ｍｇ／Ｌ以下が好ましく、１００ｍｇ／Ｌ以下がより好ましい。 The amount of the cationic polymer flocculant to be mixed with the industrial wastewater may be appropriately determined depending on the type of industrial wastewater to be treated, the type of iron-based inorganic flocculant to be used in combination, etc., and is not particularly limited. From the viewpoint of high impurity removal effect, it is preferably 10 mg/L or more, and more preferably 20 mg/L or more, and from the viewpoint of excellent economy, it is preferably 200 mg/L or less, and more preferably 100 mg/L or less.
　本工程における固液分離の手法としては、産業廃液において一般的に使用される手法であればよく、特に限定はないが、凝集沈殿、濾過、遠心分離、圧搾、膜分離等の方法が挙げられる。 The method of solid-liquid separation in this process may be any method commonly used for industrial wastewater, and is not particularly limited, but examples include coagulation sedimentation, filtration, centrifugation, squeezing, membrane separation, etc.
　第一上澄み液中には、溶解された状態の鉄系無機凝集剤及びカチオン系高分子凝集剤が含まれるため、そのｐＨは、５以下に調整された酸性溶液の状態になっている。 The first supernatant contains dissolved iron-based inorganic flocculants and cationic polymer flocculants, so its pH is adjusted to 5 or less, making it an acidic solution.
　第一上澄み液は、処理原料である産業廃液に比べると、不純物が低減されているために、その色度が低減された有色液になっている。 The first supernatant liquid has fewer impurities than the industrial wastewater used as the raw material for treatment, making it a colored liquid with reduced chromaticity.
（アルカリ処理工程）
　本工程は、前記第一上澄み液のｐＨを、アルカリ剤を用いて８以上に調整する工程である。このようにアルカリ処理を行い、続く第二沈殿処理を行うことで、前記第一上澄み液中の着色成分を凝集し易くする効果がある。 (Alkaline treatment step)
This step is a step of adjusting the pH of the first supernatant to 8 or more using an alkaline agent. By carrying out the alkaline treatment and the subsequent second precipitation treatment in this manner, it is possible to facilitate aggregation of the colored components in the first supernatant.
　前記アルカリ剤としては、特に限定はないが、水酸化ナトリウム、水酸化カリウム、水酸化カルシウム、水酸化マグネシウム等が挙げられる。
　前記アルカリ剤の種類及び量については、第一上澄み液のｐＨを８以上に調整できればよく、特に限定はない。 The alkaline agent is not particularly limited, but examples thereof include sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, and the like.
The type and amount of the alkaline agent are not particularly limited as long as they can adjust the pH of the first supernatant to 8 or higher.
（第二沈殿処理工程）
　本工程は、前記のようにアルカリ性に調整された第一上澄み液に、鉄系無機凝集剤を混合し、次いで、アルカリ剤を混合してｐＨを６以上に調整し、次いで、カチオン系高分子凝集剤を混合し、固液分離して第二上澄み液を取り出す工程である。 (Second Precipitation Treatment Step)
This process is a process in which an iron-based inorganic flocculant is mixed with the first supernatant liquid adjusted to alkaline as described above, then an alkaline agent is added to adjust the pH to 6 or more, and then a cationic polymer flocculant is added, followed by solid-liquid separation to extract a second supernatant liquid.
　本工程で使用する鉄系無機凝集剤は、前記第一沈殿処理工程で使用可能なものであればよい。
　また、本工程で使用する鉄系無機凝集剤の種類は、前記第一沈殿処理工程で使用したものと同じであっても、異なっていてもよい。 The iron-based inorganic flocculant used in this step may be any one that can be used in the first precipitation treatment step.
The type of iron-based inorganic flocculant used in this step may be the same as or different from that used in the first precipitation treatment step.
　第一上澄み液に混合する前記鉄系無機凝集剤の量としては、処理対象の産業廃液の種類に応じて適宜決定すればよく、特に限定はないが、着色成分の除去効果が高い観点から、１００ｍｇ／Ｌ以上が好ましく、３００ｍｇ／Ｌ以上がより好ましく、また、経済性に優れる観点から、１００００ｍｇ／Ｌ以下が好ましく、５０００ｍｇ／Ｌ以下がより好ましく、２０００ｍｇ／Ｌ以下がさらに好ましい。 The amount of the iron-based inorganic flocculant to be mixed with the first supernatant may be appropriately determined depending on the type of industrial wastewater to be treated, and is not particularly limited. From the viewpoint of high effectiveness in removing colored components, the amount is preferably 100 mg/L or more, and more preferably 300 mg/L or more. From the viewpoint of excellent economy, the amount is preferably 10,000 mg/L or less, more preferably 5,000 mg/L or less, and even more preferably 2,000 mg/L or less.
　本工程において、前記鉄系無機凝集剤が添加された第一上澄み液のｐＨは、酸性側になり、５以下に調整されることが好ましい。 In this process, the pH of the first supernatant to which the iron-based inorganic flocculant has been added is preferably adjusted to an acidic pH of 5 or less.
　次いで、前記の第一上澄み液に、アルカリ剤を添加する。
　本工程では、鉄系無機凝集剤を添加することで低減した第一上澄み液のｐＨを、再度アルカリ剤を添加して上昇させることで、カチオン系高分子凝集剤を添加した場合に、着色成分をより沈殿させやすくする効果がある。 Next, an alkaline agent is added to the first supernatant.
In this process, the pH of the first supernatant liquid, which has been reduced by adding an iron-based inorganic flocculant, is raised again by adding an alkaline agent, which has the effect of making it easier to precipitate the colored components when a cationic polymer flocculant is added.
　本工程で使用するアルカリ剤は、前記アルカリ処理工程で使用可能なものであればよい。
　また、本工程で使用するアルカリ剤の種類は、前記アルカリ処理工程で使用したものと同じであっても、異なっていてもよい。 The alkaline agent used in this step may be any agent that can be used in the alkaline treatment step.
The type of alkaline agent used in this step may be the same as or different from that used in the alkaline treatment step.
　前記アルカリ剤の種類及び量については、第一上澄み液のｐＨを６以上に調整できればよい。 The type and amount of the alkaline agent should be sufficient to adjust the pH of the first supernatant to 6 or higher.
　次いで、ｐＨが６以上に調整された第一上澄み液にカチオン系高分子凝集剤を添加することで、酸性条件でカチオン系高分子凝集剤を使用している前記第一沈殿処理工程とは異なり、着色成分をより効率よく沈殿させることが可能となる。
　本工程で使用する前記カチオン系高分子凝集剤は、前記第一沈殿処理工程で使用可能なものであればよい。
　また、本工程で使用するカチオン系高分子凝集剤の種類は、前記第一沈殿処理工程で使用したものと同じであっても、異なっていてもよい。 Next, by adding a cationic polymer flocculant to the first supernatant liquid whose pH has been adjusted to 6 or more, it becomes possible to more efficiently precipitate the colored components, unlike the first precipitation treatment step in which a cationic polymer flocculant is used under acidic conditions.
The cationic polymer flocculant used in this step may be any one that can be used in the first precipitation treatment step.
The type of cationic polymer flocculant used in this step may be the same as or different from that used in the first precipitation treatment step.
　前記第一上澄み液に混合する前記カチオン系高分子凝集剤の量としては、処理対象の産業廃液の種類、併用される鉄系無機凝集剤の種類等に応じて適宜決定すればよく、特に限定はないが、着色成分の除去効果が高い観点から、１０ｍｇ／Ｌ以上が好ましく、２０ｍｇ／Ｌ以上がより好ましく、また、経済性に優れる観点から、２００ｍｇ／Ｌ以下が好ましく、１００ｍｇ／Ｌ以下がより好ましい。 The amount of the cationic polymer flocculant to be mixed with the first supernatant may be appropriately determined depending on the type of industrial wastewater to be treated, the type of iron-based inorganic flocculant to be used in combination, etc., and is not particularly limited. From the viewpoint of high effectiveness in removing colored components, the amount is preferably 10 mg/L or more, and more preferably 20 mg/L or more, and from the viewpoint of excellent economy, the amount is preferably 200 mg/L or less, and more preferably 100 mg/L or less.
　本工程における固液分離の手法としては、第一沈殿処理工程で使用可能な手法であればよく、特に限定はない。 The method of solid-liquid separation in this step is not particularly limited as long as it is a method that can be used in the first precipitation treatment step.
　本工程で得られる第二上澄み液は、有色の程度が顕著に低減された液体であり、例えば、色度を測定した場合に、コーヒー廃液でも１４０度未満まで低減することが可能である。 The second supernatant liquid obtained in this process is a liquid in which the degree of coloration has been significantly reduced; for example, when measuring the chromaticity, it is possible to reduce the chromaticity of even coffee waste liquid to less than 140 degrees.
　前記第二上澄み液は、不純物に加えて、着色成分が顕著に低減されているため、環境中に、より安全に排出することが可能な液体である。 The second supernatant liquid is a liquid that can be discharged into the environment more safely because the content of coloring components has been significantly reduced in addition to impurities.
　本発明の方法において、鉄系無機凝集剤、カチオン系高分子凝集剤又はアルカリ剤を添加した場合に実施する撹拌条件については、常温下で行えばよく、撹拌速度等についても特に限定はない。 In the method of the present invention, when an iron-based inorganic flocculant, a cationic polymer flocculant, or an alkaline agent is added, the stirring conditions may be performed at room temperature, and there are no particular limitations on the stirring speed, etc.
　また、本発明の方法で分離された固形分は、常法に基づいて廃棄処理すればよい。 The solid matter separated by the method of the present invention can be disposed of according to conventional methods.
　なお、本発明の方法において、第一沈殿処理工程及び第二沈殿処理工程ではいずれも鉄系無機凝集剤及びカチオン系高分子凝集剤を使用するのに関わらず、第二沈殿処理工程で着色成分が効率的に除去できるメカニズムについては、その詳細は不明であるが、第一沈殿処理工程で、固形分の多くが除去されて得られた第一上澄み液を、そのｐＨを６以上に調整してから、カチオン系高分子凝集剤を混合することで、残存している着色成分が効率よく取り除かれることで色度が落ちると考えられる。 In the method of the present invention, although an iron-based inorganic flocculant and a cationic polymer flocculant are used in both the first and second precipitation treatment steps, the details of the mechanism by which colored components can be efficiently removed in the second precipitation treatment step are unknown. However, it is believed that the color is reduced by efficiently removing the remaining colored components by adjusting the pH of the first supernatant obtained in the first precipitation treatment step from most of the solids to 6 or higher and then mixing with the cationic polymer flocculant.
　本発明の方法では、前記のように、鉄系無機凝集剤、カチオン系高分子凝集剤を用いた固液分離を、ｐＨ条件を調整しながら繰り返し行うことで、生物処理等の他の処理は利用せずとも、産業廃液から着色成分を顕著に低減できる点で、簡便性及び経済性に優れるという利点がある。
　また、本発明の方法では、着色成分に加えて、前記産業廃液中の不純物、例えば、リンであっても低減できるため、脱色後の処理液を環境中に排出しても、環境に対する影響を顕著に低減することができる。 As described above, the method of the present invention has the advantages of being simple and economical in that the coloring components can be significantly reduced from industrial wastewater by repeatedly performing solid-liquid separation using an iron-based inorganic flocculant and a cationic polymer flocculant while adjusting the pH conditions, without using other treatments such as biological treatment.
Furthermore, the method of the present invention can reduce impurities in the industrial wastewater, such as phosphorus, in addition to the coloring components, so that even if the decolorized treatment liquid is discharged into the environment, the impact on the environment can be significantly reduced.
（実施例１：畜産廃液の脱色方法）
　畜産廃液として、畜産排水を活性汚泥処理して得られる放流水を原水とした。
　前記原水は、ｐＨ７.１、茶褐色（色度：８５０度）の液体であった。 (Example 1: Method for decolorizing livestock wastewater)
As the livestock wastewater, effluent obtained by treating livestock wastewater with activated sludge was used as raw water.
The raw water was a brown liquid with a pH of 7.1 (color index: 850 degrees).
　なお、色度については、下水試験方法 ２編２章４節２に記載の透過光測定法に基づいて、分光光度計（島津製作所、ＵＶ－１８００）を用いて、吸光光度法により、３９０ｎｍ付近の吸光度で、試料の呈する淡黄色から黄褐色の程度を測定した。
　具体的には下記の手順で色度の測定を行った。
 
（試験方法）
　試料は、ろ紙５種Ｃ、又は孔径１μｍ以下のろ過材でろ過するか、又は約３，０００ｒｐｍで２０分間、遠心分離して濁りを除去する。この試料１００ｍlの一部を吸収セル（光路長５０ｎｍ）にとり、分光光度計を用いて波長３９０ｎｍ付近における吸光度を測定する。
　なお、試料の色度が1００度以上のときは、試料の適量をとり、水を加えて１００ｍｌとする。
 
（検量線の作成）
　色度標準液（１００度）１．０～１００ｍｌを段階的に数個の全量フラスコ１００ｍｌにとり、水を標線まで加える。以下、試験操作と同様にして吸光度を測定し、色度と吸光度の関係を求める。
　なお、本法の定量範囲は、０～１００度で、最小単位は１度である。
 
（色度の計算）
　検量線を用いて、試料の吸光度を色度に換算する。
　試料の色度は、次式（１）によって算出する。 
Ｃ＝Ｃｓ×Ｄ 　　　　（１）
Ｃ：色度 
ＣＳ：検量線から求めた色度 
Ｄ：希釈倍率  Regarding color, the degree of light yellow to yellowish brown color of the sample was measured by absorptiometry using a spectrophotometer (Shimadzu Corporation, UV-1800) based on the transmitted light measurement method described in Section 4, Chapter 2, Part 2 of the Sewage Testing Methods. The absorbance at around 390 nm was measured.
Specifically, the chromaticity was measured according to the following procedure.

(Test method)
The sample is filtered through filter paper type 5C or a filter material with a pore size of 1 μm or less, or centrifuged at about 3,000 rpm for 20 minutes to remove turbidity. A portion of 100 ml of this sample is placed in an absorption cell (path length 50 nm) and the absorbance at a wavelength of about 390 nm is measured using a spectrophotometer.
If the color of the sample is 100 degrees or more, take an appropriate amount of the sample and add water to make it 100 ml.

(Creating a calibration curve)
Put 1.0 to 100 ml of the color standard solution (100 degrees) into several 100 ml volumetric flasks in stages and add water up to the mark. Then, measure the absorbance in the same manner as in the test procedure, and obtain the relationship between color and absorbance.
The quantification range of this method is 0 to 100 degrees, with the minimum unit being 1 degree.

(Calculation of chromaticity)
Using the calibration curve, the absorbance of the sample is converted to color.
The chromaticity of the sample is calculated by the following formula (1).
C = Cs × D (1)
C: Chromaticity
C S : Chromaticity obtained from the calibration curve
D: Dilution ratio
　前記原水に、塩化第二鉄を５３６ｍｇ／Ｌになるように添加し、５００ｒｐｍで５分間撹拌した（ｐＨ３．０）。
　次いで、カチオン系高分子凝集剤（カチオン性ポリアクリルアミド）を４０ｍｇ／Ｌになるように添加し、２５０ｒｐｍで５分間撹拌した。
　次いで、ろ紙を用いて固液分離して、第一上澄み液（ｐＨ３．０、淡褐色）を得た。
　第一上澄み液に水酸化ナトリウム水溶液を添加してｐＨ１０．０に調整した。
　次いで、第一上澄み液に塩化第二鉄を３２２ｍｇ／Ｌになるように添加して、５００ｒｐｍで５分間攪拌した（ｐＨ３．３）。
　次いで、第一上澄み液に水酸化ナトリウム水溶液を添加して、ｐＨ６．７に調整し、５００ｒｐｍで５分間撹拌した。
　次いで、第一上澄み液にカチオン系高分子凝集剤（カチオン性ポリアクリルアミド）を８０ｍｇ／Ｌになるように添加して、２５０ｒｐｍで５分間撹拌した。
　次いで、ろ紙を用いて固液分離して、第二上澄み液（ｐＨ６．７、淡褐色、色度７５度）を得た。 Ferric chloride was added to the raw water so as to give a concentration of 536 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 3.0).
Next, a cationic polymer flocculant (cationic polyacrylamide) was added to the solution to give a concentration of 40 mg/L, and the solution was stirred at 250 rpm for 5 minutes.
Next, solid-liquid separation was performed using filter paper to obtain a first supernatant liquid (pH 3.0, light brown).
The first supernatant was adjusted to pH 10.0 by adding an aqueous solution of sodium hydroxide.
Next, ferric chloride was added to the first supernatant to a concentration of 322 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 3.3).
Next, an aqueous solution of sodium hydroxide was added to the first supernatant to adjust the pH to 6.7, and the mixture was stirred at 500 rpm for 5 minutes.
Next, a cationic polymer flocculant (cationic polyacrylamide) was added to the first supernatant to a concentration of 80 mg/L, and the mixture was stirred at 250 rpm for 5 minutes.
Next, solid-liquid separation was performed using filter paper to obtain a second supernatant liquid (pH 6.7, light brown, color degree 75 degrees).
　得られた第二上澄み液は、ｐＨが中性付近に調整され、原水に比べて色度が顕著に低い液体になっており、希釈することなくそのまま環境中に安全に排出できるものであった。
　本発明では、上記のような廃液の脱色が、短時間で達成できることから、脱色効果に優れ、また、鉄系無機凝集剤、カチオン系高分子凝集剤を添加するだけで実施可能であることから、他の特別な設備は必要なく、簡便で、実用性に優れた脱色方法であることがわかる。 The obtained second supernatant liquid had a pH adjusted to approximately neutral and a significantly lower color than the raw water, and could be safely discharged into the environment as is without dilution.
In the present invention, the decolorization of the waste liquid as described above can be achieved in a short time, and therefore the decolorization effect is excellent. Furthermore, since the decolorization can be carried out by simply adding an iron-based inorganic flocculant and a cationic polymer flocculant, no other special equipment is required, and therefore the decolorization method is simple and has excellent practicality.
（実施例２：コーヒー工場排水(原水)の脱色方法）
　食品工場廃液として、コーヒー工場から排出される廃液を原水とした。
　前記原水は、ｐＨ５．８、黒色（色度３４００度）の液体であった。 (Example 2: Method for decolorizing wastewater (raw water) from a coffee factory)
The raw water used for the food processing plant was wastewater discharged from a coffee factory.
The raw water was a black liquid with a pH of 5.8 (color degree 3400 degrees).
　前記原水に塩化第二鉄を５３６ｍｇ／Ｌになるように添加して、５００ｒｐｍで５分間撹拌した（ｐＨ４．５）。
　次いで、カチオン系高分子凝集剤（カチオン性ポリアクリルアミド）を４０ｍｇ／Ｌとなるよう添加して、２５０ｒｐｍで５分間撹拌した。
　次いで、ろ紙を用いて固液分離して、第一上澄み液（ｐＨ４．５、淡緑色）を得た。
　次いで、第一上澄み液に水酸化ナトリウム水溶液を添加して、ｐＨ８．４に調整した。
　次いで、第一上澄み液に塩化第二鉄を３２２ｍｇ／Ｌになるように添加して、５００ｒｐｍで５分間撹拌した（ｐＨ６．０）。
　次いで、第一上澄み液に水酸化ナトリウム水溶液を添加して、ｐＨ７．０に調整した。
　次いで、第一上澄み液にカチオン系高分子凝集剤（カチオン性ポリアクリルアミド）を４０ｍｇ／Ｌとなるように添加して、２５０ｒｐｍで５分間撹拌した。
　次いで、ろ紙を用いて固液分離して、第二上澄み液（ｐＨ７．０、淡褐色、色度１３０度）を得た。 Ferric chloride was added to the raw water so as to give a concentration of 536 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 4.5).
Next, a cationic polymer flocculant (cationic polyacrylamide) was added to the solution so as to give a concentration of 40 mg/L, and the solution was stirred at 250 rpm for 5 minutes.
Next, solid-liquid separation was performed using filter paper to obtain a first supernatant liquid (pH 4.5, pale green).
Next, an aqueous solution of sodium hydroxide was added to the first supernatant to adjust the pH to 8.4.
Next, ferric chloride was added to the first supernatant to a concentration of 322 mg/L, and the mixture was stirred at 500 rpm for 5 minutes (pH 6.0).
Next, an aqueous solution of sodium hydroxide was added to the first supernatant to adjust the pH to 7.0.
Next, a cationic polymer flocculant (cationic polyacrylamide) was added to the first supernatant to give a concentration of 40 mg/L, and the mixture was stirred at 250 rpm for 5 minutes.
Next, solid-liquid separation was performed using filter paper to obtain a second supernatant liquid (pH 7.0, light brown, color degree 130 degrees).
　得られた第二上澄み液は、ｐＨが中性付近に調整され、原水に比べて色度が１４０未満と顕著に低い液体になっており、希釈することなくそのまま環境中に安全に排出できるものであった。
　本発明では、上記のような廃液の脱色が、短時間で達成できることから、脱色効果に優れ、また、鉄系無機凝集剤、カチオン系高分子凝集剤を添加するだけで実施可能であることから、他の特別な設備は必要なく、簡便で、実用性に優れた脱色方法であることがわかる。 The obtained second supernatant liquid had a pH adjusted to near neutral and a significantly lower color value of less than 140 compared to the raw water, and could be safely discharged into the environment as is without dilution.
In the present invention, the decolorization of the waste liquid as described above can be achieved in a short time, and therefore the decolorization effect is excellent. Furthermore, since the decolorization can be carried out by simply adding an iron-based inorganic flocculant and a cationic polymer flocculant, no other special equipment is required, and therefore the decolorization method is simple and has excellent practicality.
（実施例３：畜産廃液の脱色方法）
　牛舎から排出された畜産廃液を一般的な生物処理に供した後の有色廃液を原水として、実施例１と同様の方法で脱色処理した。
　原水（ｐＨ８．６１）及び脱色処理水（ｐＨ５．８５）の、色度及びＴ－Ｐ（全リン）を表１に示す。 (Example 3: Method for decolorizing livestock wastewater)
The colored wastewater discharged from a cowshed was subjected to a general biological treatment, and the raw water was subjected to a decolorization treatment in the same manner as in Example 1.
The color and TP (total phosphorus) of the raw water (pH 8.61) and the decolorized water (pH 5.85) are shown in Table 1.
　なお、リンの量については、リン計量方法「ＪＩＳ　Ｋ　０１０２‐４６.３．１」に記載のペルオキソ二硫酸カリウム分解法を用いて、全リン濃度（Ｔ－Ｐ）を測定した。 The amount of phosphorus was measured as the total phosphorus concentration (T-P) using the potassium peroxodisulfate decomposition method described in the phosphorus measurement method "JIS K 0102-46.3.1."
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の結果より、本発明の方法は、産業廃液の脱色の効果に加えて、脱リンの効果も有することがわかる。
　したがって、本発明の方法を用いて脱色した後の処理液を環境中に排出しても、環境に対する影響を顕著に低減することができる。 From the results in Table 1, it is apparent that the method of the present invention has an effect of removing phosphorus in addition to the effect of decolorizing industrial wastewater.
Therefore, even if the treatment liquid after decolorization using the method of the present invention is discharged into the environment, the impact on the environment can be significantly reduced.

Claims (4)

  1. 　産業廃液の脱色方法であって、
    　産業廃液に鉄系無機凝集剤及びカチオン系高分子凝集剤を混合し、固液分離して第一上澄み液を取り出す第一沈殿処理工程、
    　第一上澄み液にアルカリ剤を混合して第一上澄み液のｐＨを８以上に調整するアルカリ処理工程、
    　ｐＨ調整された第一上澄み液に、鉄系無機凝集剤を混合し、次いで、アルカリ剤を混合してｐＨを６以上に調整し、次いで、カチオン系高分子凝集剤を混合し、固液分離して第二上澄み液を取り出す、第二沈殿処理工程
    を有することを特徴とする、産業廃液の脱色方法。     A method for decolorizing industrial wastewater, comprising the steps of:
    a first precipitation treatment step in which an iron-based inorganic flocculant and a cationic polymer flocculant are mixed with the industrial wastewater, followed by solid-liquid separation to extract a first supernatant liquid;
    an alkali treatment step of mixing an alkaline agent with the first supernatant to adjust the pH of the first supernatant to 8 or more;
    A method for decolorizing industrial wastewater, comprising a second precipitation treatment step of mixing an iron-based inorganic flocculant with a pH-adjusted first supernatant, then mixing an alkaline agent to adjust the pH to 6 or more, then mixing a cationic polymer flocculant, and subjecting the mixture to solid-liquid separation to extract a second supernatant.
  2. 　前記鉄系無機凝集剤が、塩化第一鉄、塩化第二鉄又はポリ硫酸第二鉄である、請求項１に記載の産業廃液の脱色方法。 The method for decolorizing industrial wastewater according to claim 1, wherein the iron-based inorganic coagulant is ferrous chloride, ferric chloride, or polyferric sulfate.
  3. 　前記カチオン系高分子凝集剤が、アクリル系又はメタクリル系のカチオン性高分子凝集剤である、請求項１又は２に記載の産業廃液の脱色方法。 The method for decolorizing industrial wastewater according to claim 1 or 2, wherein the cationic polymer flocculant is an acrylic or methacrylic cationic polymer flocculant.
  4. 　前記産業廃液が、畜産廃液、食品工場廃液又は染色工場廃液である、請求項１又は２に記載の産業廃液の脱色方法。 The method for decolorizing industrial wastewater according to claim 1 or 2, wherein the industrial wastewater is livestock wastewater, food factory wastewater, or dye factory wastewater.
PCT/JP2023/033958 2022-10-06 2023-09-19 Method for decolorizing industrial waste liquid WO2024075518A1 (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54156341A (en) * 1978-05-31 1979-12-10 Ebara Corp Treatment of waste water
JPH0623369A (en) * 1992-01-27 1994-02-01 Sandoz Ag Method for disposal of used aqueous aluminum solution
JPH06165993A (en) * 1992-08-27 1994-06-14 Shikoku Chem Corp Decoloring chemical for waste water of dye and dyeing industry and dyeing method therefor
JPH09174061A (en) * 1995-12-28 1997-07-08 Hodogaya Chem Co Ltd Treatment of color substance-containing waste water
JP2001269504A (en) * 2000-03-28 2001-10-02 Nittetsu Mining Co Ltd Novel flocculant and method for manufacturing the same
JP2008055277A (en) * 2006-08-30 2008-03-13 Konica Minolta Business Technologies Inc Method for decolorizing colored waste water
JP2011050900A (en) * 2009-09-03 2011-03-17 Fuji Xerox Co Ltd Water treatment apparatus and water treatment method

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS54156341A (en) * 1978-05-31 1979-12-10 Ebara Corp Treatment of waste water
JPH0623369A (en) * 1992-01-27 1994-02-01 Sandoz Ag Method for disposal of used aqueous aluminum solution
JPH06165993A (en) * 1992-08-27 1994-06-14 Shikoku Chem Corp Decoloring chemical for waste water of dye and dyeing industry and dyeing method therefor
JPH09174061A (en) * 1995-12-28 1997-07-08 Hodogaya Chem Co Ltd Treatment of color substance-containing waste water
JP2001269504A (en) * 2000-03-28 2001-10-02 Nittetsu Mining Co Ltd Novel flocculant and method for manufacturing the same
JP2008055277A (en) * 2006-08-30 2008-03-13 Konica Minolta Business Technologies Inc Method for decolorizing colored waste water
JP2011050900A (en) * 2009-09-03 2011-03-17 Fuji Xerox Co Ltd Water treatment apparatus and water treatment method

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