JPH10286589A - Decoloration of wastewater and treatment method of hardly decomposable substance using hydrogen peroxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To oxidize and decompose color substances and hardly decomposable substances in practical wastewater at low cost with lowered energy consumption by adding cultivated white putrefactive bacteria to a reaction tank into which the practical wastewater flows, further adding hydrogen peroxide out of the reaction tank, and utilizing the decomposition enzyme produced by the white putrefactive bacteria. SOLUTION: A mixed water MW of raw water OW, which is practical wastewater, and white putrefactive bacteria is stored in a reaction tank R. Hydrogen peroxide is added to the reaction tank R. While becoming fine bubbles, air blown from a blower B is mixed with the mixed water MW by an aeration apparatus S and supplied to the aerobic white putrefactive bacteria. The white putrefactive bacteria in the mixed water MW propagates while decomposing organic matter contained in the raw water OW or a carbon source added from outside, forms flock like aggregate, and floats in the mixed water in suspended state. The color substances contained in the raw water OW are decomposed and decolored and also hardly decomposable substances are decomposed into smaller molecules by the hydrogen peroxide decomposition enzyme released by the propagated white putrefactive bacteria.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment method for industrial wastewater such as sewage treatment, night soil treatment, leachate wastewater treatment, small-scale sewage treatment, and sewage sludge heat-treating separation liquid. The present invention relates to a method for decolorizing wastewater and treating a hardly decomposable substance, which decomposes (decolorizes) a colored substance using hydrogen peroxide and enables oxidative decomposition of a hardly decomposable substance.

[0002]

2. Description of the Related Art Generally, wastewater such as sewage treatment, human waste treatment, leachate drainage treatment, small-scale sewage treatment, and sewage sludge heat treatment separation liquid contains a wide range of organic and inorganic substances.
Among these, in particular, it is difficult to decompose a colored substance, that is, decolorize or remove a hardly decomposable substance, using a conventional biological reaction removing apparatus. For example, an activated sludge method used in ordinary sewage treatment, a batch activated sludge method in which the entire process of the activated sludge method is carried out in one complete mixing reaction tank, or a method in which microorganisms are fixed to a resin material to purify wastewater. Although the biofilm method and the like exist, in these biological reaction removing equipment, the decomposition of easily decomposable substances such as water-soluble, low polymerization degree and low molecular weight was limited.

[0003] The difficulty in decoloring or removing hardly decomposable substances by biological treatment is that colored substances and hardly decomposable substances have extremely strong intermolecular forces, and ordinary bacteria can decompose them. It is because it does not have. In particular, colored substances are often difficult-to-decompose substances at the same time, and the inability to decolorize wastewater has the same meaning as the inability to decompose insoluble substances.

[0004] Refractory substances are generally insoluble in water,
In many cases, the substance is a substance having a high degree of polymerization and a high molecular weight, and specific examples of the coloring-hardly decomposable substance include humin, lignin, and melanoidin-related compounds. Here, humin is a black insoluble matter generated when hydrolyzing proteins, and lignin is 2% in wood along with cellulose.
Aromatic compounds present at 0-30%. As described above, a biologically-derived colored compound is often a substance that is difficult to be decomposed by conventional biological treatment.

Therefore, conventional decolorization or removal of hardly decomposable substances has had to rely on physicochemical treatment. The physicochemical treatment method includes a coagulation sedimentation method in which an inorganic coagulant such as ferric chloride and PAC (polyaluminum chloride) is introduced into wastewater, and a large amount of a strong oxidizing agent such as sodium hypochlorite and ozone. And a decomposition method by ultraviolet irradiation.

[0006]

The physicochemical treatment method has the following disadvantages. The coagulation sedimentation method is a method in which a coagulant is injected into wastewater to ionize it, and the solid matter in the wastewater is electrically neutralized and forcibly settled. Released with water causing environmental pollution. In particular, polyacrylamide, a synthetic polymer flocculant widely used in recent years, is excellent in terms of flocculation ability, but this substance itself shows strong mutagenicity, and carcinogenicity to the monomer acrylamide contained in polyacrylamide -Due to the presence of neurotoxin, its persistence is a concern. In addition, PAC has been pointed out as a toxic substance of Alzheimer's disease.

[0007] Sodium hypochlorite and ozone have a great effect on decolorization due to decomposition of colored substances, particularly on decolorization of organic dyes, due to bleaching action due to their strong oxidizing power. However, these chemicals are not only expensive but also extremely toxic to living organisms. In the case of ozone, it is known that it has mutagenic properties and is involved in the generation of carcinogenic compounds, and the ozone generator is expensive.

[0008] Ultraviolet irradiation does not use any chemicals, so it is safest against environmental impact, but the ultraviolet irradiation equipment becomes extremely expensive. Ultraviolet rays have been studied as a means of disinfecting high-quality waterworks, but if there is a suspended substance or chromaticity component (colored substance) in water, the ultraviolet rays are blocked and the sterilizing ability is rapidly reduced. The same is true for the decolorizing effect. The higher the chromaticity of the wastewater, the shorter the distance that the ultraviolet light can reach, and the lower the decolorizing effect and the ability to decompose the hardly decomposable substances. Practical application is not progressing.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an improved biological treatment method effective for decomposing easily decomposable substances has been proposed to improve decolorization and difficult decomposition. It can be applied to the decomposition of toxic substances.
That is, the method for decolorizing wastewater and treating hardly decomposable substances according to the present invention includes a step of cultivating white rot fungi while cultivating white rot fungi in advance in the wastewater to be treated, and an actual drainage of the adjusted white rot fungi. And adding hydrogen peroxide to the reaction tank from the outside, and using the hydrogen peroxide degrading enzyme generated by the white rot fungus to remove colored substances and hardly decomposable substances in actual wastewater. And a step of oxidative decomposition.

In the step of adding the white rot fungi to the reaction tank, a method using an activated sludge method, a method using a microbial membrane to which the white rot fungi are adsorbed and fixed, and a microorganism immobilized with the white rot fungi are prepared. A method of suspending the inside is provided as a specific example.

[0011] The present invention provides a treatment method for introducing wastewater decolorized and decomposed in the reaction tank into a membrane separation device or a sedimentation tank to separate solid components such as white rot fungi and decomposed products and clear treated water.

The present invention provides a processing method in which the reaction vessels are provided in multiple stages, and the reaction vessels are aerated by an air blower to increase the reaction efficiency.

[0013]

DETAILED DESCRIPTION OF THE INVENTION The present invention intends to utilize microorganisms for decolorizing wastewater and removing hardly decomposable substances. The removal of easily decomposable organic substances has conventionally utilized the oxidative decomposition ability of microorganisms such as an activated sludge method. This method makes it possible to efficiently remove contaminants with simple equipment because the biological activity of microorganisms is used. If decolorization and removal of hardly decomposable substances in wastewater can be performed by using microorganisms, an inexpensive energy saving system can be constructed. Further, as described above, the colored component to be decolorized is often structurally the same as the hardly decomposable substance, so that both substances can be simultaneously removed.

The present inventors have conducted intensive studies on microorganisms that decolorize wastewater and decompose hardly decomposable substances, and as a result, have found that white rot fungi, a kind of fungi, can achieve the object of the present invention. The white-rot fungi used in the present invention belong to basidiomycetes, and are basidiomycetes having the ability to strongly degrade cellulose lignin among basidiomycetes that generally rot wood. Specifically, Coriolus (Coriolu)
s), Lenzites betulina (Lenzites b)
aerobes such as E. etulina, Pleurotus ostreatus and Pleurotus ostreatus, and in particular Coriolus hirsutus available from the Fermentation Institute (IFO).
(Shirstus) IFO4917 strain is the most preferred white rot fungus for the present invention. Of course, not only the above-mentioned white-rot fungi but also other known white-rot fungi can be used in the present invention.

Further, the present inventors have found that the decolorization of white rot fungi and the ability to decompose hardly decomposable substances depend on hydrogen peroxide and hydrogen peroxide degrading enzyme (peroxidase) produced by white rot fungi. It became. That is,
Peroxidase, which simultaneously produces hydrogen peroxide generated by white rot fungi, decomposes to form active oxygen, which oxidatively decomposes colored substances to decolorize and oxidatively decomposes hardly decomposable substances.

[0016] However, in the decomposition action of only white rot fungi,
The activity of the white rot fungus affects the decolorizing effect, and a stable decomposition action may not be obtained. The cause of the decomposition power of white rot fungi is active oxygen generated by peroxidase decomposing hydrogen peroxide. The present inventors have come up with the idea that, if hydrogen peroxide is externally added to the reaction vessel by weight, the white rot fungi may increase the active oxygen by the peroxidase already generated. As a result of repeating the experiment, it was confirmed that peroxidase produced by the white rot fungi remained in the reaction tank, and the hydrogen peroxide added under the load was decomposed by this enzyme, and the active oxygen in the reaction tank increased. . In addition, the quantitative relationship between the amount of hydrogen peroxide added by weight and the amount of active oxygen can be confirmed. According to the present invention, stable decolorization and decomposition of hardly decomposable substances are not affected by the activity of white rot fungi. Came to get.

The concentration (addition rate) of hydrogen peroxide added to the reaction vessel by weight may be 0.1 mg / l to 5 mg / l, more preferably 0.5 mg / l to 3 mg / l. The lower limit is a concentration that is not affected by the activity of white rot fungi, and the upper limit is a concentration at which decomposition efficiency does not increase even if added more. Decolorization efficiency and decomposition efficiency depend on the concentration of hydrogen peroxide.
It was found to increase from 5% to 95% or more.

The white-rot fungus of the present invention is firstly a GPY medium (eg, 2.0% glucose, 0.3% peptone, 0.2% yeast extract, the balance distilled water, pH 6.0) as a liquid medium.
0) and cultured with shaking at 20-30 ° C for 2-4 days. As a medium for white rot fungi, a known agar medium may be used in addition to the above GPY medium.

Next, the cells are acclimated (cultivated) for 2 to 10 days in the target wastewater while culturing them. This pretreatment is an important requirement for the present invention, and is intended for the white rot fungi to be gradually adapted to the target wastewater. The concentration is adjusted to 20 to 100% depending on the amount of the colored component in the wastewater. The concentration of the colored component of the wastewater is represented by chromaticity, and in the case of wastewater having a high chromaticity, the adaptation may be divided into a plurality of stages from a low concentration to a high concentration. For example, it is possible to improve the maximum efficiency at the actual drainage treatment stage, such as adjusting to 50% concentration, then adjusting to 100% concentration, and effectively shifting to the next actual drainage treatment.

Next, in the actual wastewater treatment, the cells of the white-rot fungi cultured while acclimating are collected in the form of pellets (granules).
This is used as an inoculum. What concentrated this cell,
Various types of cells, such as those that have been dried for ease of transportation and handling, and those that have been diluted, are objects of the present invention. The cells are added to a reaction tank described below. Further, in actual wastewater treatment, there may be a case where the content of organic matter is small, so that the cells are cultured in a reaction tank holding white rot fungi, so that sugars such as glucose, sucrose, fructose, alcohols, and organics are used as carbon sources. It is desirable to add a predetermined amount of acid.

In order to apply the present invention to actual wastewater treatment, the following three types can be considered. The first is the activated sludge method, the second
Is the microbial membrane method and the third is the immobilized microorganism method. However, in any method, in order to activate aerobic white rot bacteria, a gas containing oxygen, mainly air, is supplied to the reaction tank, and the dissolved oxygen DO in the reaction tank is 0.5 mg / It is desirable to maintain 1 or more. Also, the water temperature in the reaction tank is 15 ~
Maintain at 30 ° C, preferably 25-30 ° C. If the amount is less than the lower limit, the activity of the white-rot fungi decreases, and if the amount is more than the upper limit, the bacteria cannot be stably maintained.

FIG. 1 shows an actual wastewater treatment system using the activated sludge method. In the reaction tank R, a mixed liquid MW of raw water OW, which is actual wastewater, and the above-mentioned white rot fungus is stored. Hydrogen peroxide (H ₂ O ₂ ) is added to the reaction vessel R. Blower B
The air sent from the air is converted into fine air bubbles by the aeration device S and mixed into the mixed solution MW to give air to the aerobic white rot bacteria. White rot fungi in raw water OW in mixed solution MW
Proliferates while decomposing organic substances contained in the water or a carbon source supplied from the outside, and floats in a mixed liquid as a floc-like mass.

The hydrogen peroxide decomposing enzyme generated by the grown white rot fungus decomposes hydrogen peroxide added from the outside in addition to the generated hydrogen peroxide to generate active oxygen. Colored substances contained in the OW are oxidatively decomposed and decolorized, and hardly decomposable substances are also decomposed into smaller molecules. These decomposition products dissipate as a gas, grow bacteria as a nutrient source, or aggregate and float in suspension.

The mixed solution MW is supplied to a membrane separation device M by a pump P.
S is sent out. In this method, solid-liquid separation of the solid component FS such as white rot fungi and decomposition products and the treated water TW is performed by the membrane separation device MS, because the precipitation property of white rot fungi in the reaction tank R is relatively small. It was to be. After the membrane separation, the treated water TW is sent to a treated water tank (not shown). As the membrane, a reverse osmosis membrane can be used. For example, an MF membrane, a UF membrane, an RO membrane, or the like is used. The mixed solution MW is permeated through the reverse osmosis membrane by a high-pressure pump to be separated into a solid and a liquid. The solid component FS is fed back to the reaction tank R again. In this way, the raw water OW is continuously processed.

FIG. 2 shows an actual wastewater treatment system using the microbial membrane method. The white rot fungus adjusted to the surface of the resin plate by drainage is immobilized using a known immobilization technique. That is, a microbial membrane is formed on the surface of the resin plate, which is referred to as a microbial membrane method. The resin modules PM having the microbial membrane formed thereon are stacked in multiple stages while having a gap through which water can pass. The resin module PM is loaded into the reaction tank R, and the raw water OW is passed through the resin module PM while adding hydrogen peroxide (H ₂ O ₂ ). At the same time, the hardly decomposable substances contained in the wastewater are oxidatively decomposed by white rot fungi.
The operations of the blower B and the aerator S are the same as those in FIG.

The intermediate water IW containing the decomposed product is supplied to the sedimentation basin PP
And solids such as decomposed products settle in the settling basin PP. The clear supernatant is sent to a treated water tank (not shown) as treated water TW.

FIG. 3 shows an actual wastewater treatment system using the immobilized microorganism method. As a method for immobilizing microorganisms, there are a carrier binding method in which microorganisms are bonded to an insoluble carrier, a cross-linking method in which microorganisms are cross-linked with each other using a reagent, and in a fine network of a polymer gel or in a semipermeable polymer film. There are inclusive methods for encapsulating microorganisms. In FIG. 3, an inclusive method in which white rot fungi are enclosed and fixed inside a water-soluble polymer gel is used.

The immobilized microorganism FM is mixed with the mixed solution M in the reaction vessel R.
It floats in W, decolorizes and decomposes the colored substances in the raw water OW, and simultaneously oxidizes and decomposes other hardly decomposable substances. Hydrogen peroxide (H ₂ O ₂ ) is added to the inlet of the reaction vessel R. The operations of the blower B and the aerator S are the same as those in FIG. After the decomposition, the intermediate water IW is sent to a sedimentation basin PP to settle solid components such as decomposed products and immobilized microorganisms, and then a clear supernatant liquid is treated water TW as a treated water tank (not shown).
Sent to

[0029]

EXAMPLE An example of decolorization in which hydrogen peroxide was added to a reaction vessel for white rot fungi whose main bacterium was Coriolus hilutus IFO4917 was shown below. The wastewater used was a dehydrator separation liquid obtained by heat treatment and dehydration of sewage sludge. As shown in Table 1, two kinds of undiluted liquids A and B were used.
750. The chromaticity was determined as follows. After appropriately diluting the waste water with a 0.5 M sodium acetate buffer, the absorbance of the sample was measured using a wavelength of A465 mm, and the chromaticity was calculated according to the platinum-cobalt method by the following equation. Chromaticity = (absorbance of sample) × dilution magnification × 1000 / 0.2
72

[0030]

[Table 1]

The separated liquid is used to acclimate white rot fungi, specifically, white rot fungi mainly composed of Coriolus hilutus IFO4917 strain, and the separated liquid is continuously purified by the activated sludge method shown in FIG. Processed. That is, the white rot fungus was first inoculated into a GPY medium and cultured at 25 ° C. for 4 days. The cells were further cultured in the separated solution for 7 days to adjust.
Using the adapted cells as seed cells, the inside of the reaction tank was maintained at DO 2 mg / l and a water temperature of 25 ° C. by the activated sludge method shown in FIG. As shown in Table 1, from the chromaticity of the treated water and the separated liquid, the removal rate when hydrogen peroxide was added was close to 95%.
Sufficient chromaticity removal ability was confirmed. Since the removal rate without adding hydrogen peroxide was about 75%, the removal ability was increased by 20% by adding hydrogen peroxide. In addition, ethanol was used as a carbon source, and the addition amount of hydrogen peroxide was 2 mg / l.

The present invention is not limited to the above-described embodiments and examples, but encompasses various modifications and design changes within the technical scope thereof without departing from the technical idea of the present invention. .

[0033]

Industrial Applicability The present invention utilizes a special microorganism called white rot fungus, which is a kind of fungi, and furthermore, by adding hydrogen peroxide from the outside, the color of the wastewater which cannot be obtained by the conventional biological treatment method. This makes it possible to remove the hardly decomposable substances at the same time. In addition, compared with the conventional technology that relies on physicochemical treatment, it is possible to provide a wastewater treatment method that is extremely inexpensive and has a significant energy reduction effect.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an actual wastewater treatment system using an activated sludge method.

FIG. 2 is a configuration diagram of an actual wastewater treatment system using a microorganism membrane method.

FIG. 3 is a configuration diagram of an actual wastewater treatment system using an immobilized microorganism method.

[Explanation of symbols]

B: blower, FS: solid component, FM: immobilized microorganism,
IW: Intermediate water, MW: Mixed water, MS: Membrane separation device, OW
... raw, P ... pumps, PP ... sedimentation, PW ... resin module, R ... reactor, S ... aerator, TW ... treated water, H ₂
O ₂ ... hydrogen peroxide.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C02F 3/12 C02F 3/12 V

Claims (9)

[Claims] 1. A step of acclimating white rot fungi while cultivating white rot fungi in advance in a wastewater to be treated, a step of adding the adjusted white rot fungi to a reaction tank into which actual wastewater flows, and And hydrogen peroxide from the step of oxidatively decomposing colored substances and hardly decomposable substances in actual wastewater using hydrogen peroxide decomposing enzymes generated by the white rot fungus. A method for decolorizing wastewater and treating hardly decomposable substances. 2. The method according to claim 1, wherein the white rot fungus is Coriolus hirstus. 3. The treatment method according to claim 1, wherein the step of adding the white rot fungi to the reaction tank uses an activated sludge method. 4. In the step of adding the white rot fungi to a reaction tank, first, a microbial membrane on which the white rot fungi are adsorbed and fixed is prepared,
The method according to claim 1, wherein the microorganism membrane is disposed in a reaction tank. 5. The method according to claim 1, wherein in the step of adding the white rot fungi to the reaction vessel, first, immobilized microorganisms of the white rot fungi are prepared, and the immobilized microorganisms are suspended in the reaction vessel. Processing method. 6. The treatment method according to claim 1, wherein the wastewater treated in the reaction tank is introduced into a membrane separation device, and separated into solid components such as white rot fungi and clear treated water. 7. The treatment method according to claim 1, wherein the wastewater treated in the reaction tank is introduced into a sedimentation basin to separate solid components such as white rot fungi and clear treated water. 8. The processing method according to claim 1, wherein the reaction vessels are provided in multiple stages. 9. The processing method according to claim 1, wherein the reaction tank is aerated by an air blower.