JP7233473B2 - water treatment equipment - Google Patents

Description

The present invention relates to a water treatment apparatus for anaerobically biologically treating organic wastewater containing a high concentration of surfactants. More specifically, the present invention provides water treatment in which two anaerobic treatment units for anaerobically biologically treating organic wastewater containing a high concentration of surfactant are provided, and the surfactant is decomposed in the anaerobic treatment unit in the first stage. It is related to the device.

In the microbial treatment of organic wastewater, excess sludge is generated by microorganisms that have accumulated organic matter in their cells. As a method for treating excess sludge, there is a case where the cells are destroyed with a surfactant, and the sludge is treated as bacterial cell waste liquid in which the intracellular organic matter has flowed out. Such bacterial cell waste liquid contains a high concentration of surfactant, and there is a problem that the surfactant inhibits methane fermentation.

In recent years, from the viewpoint of recovering energy from waste and reducing the amount of waste, a method of methane fermentation of organic wastewater containing a high concentration of such surfactants has been developed. For example, Patent Literature 1 discloses a treatment method comprising a flocculation step of adding a calcium salt to a bacterial waste liquid to flocculate a surfactant before performing a methane fermentation step. In this method, the methane fermentation process can proceed satisfactorily by flocculating the surfactant.

JP 2014-184388 A

In the conventional biological treatment method described above, the surfactant is aggregated by adding a calcium salt, and biological treatment is performed by removing the surfactant. However, in this method, since the surfactant is recovered as a residue, further improvement is required in terms of energy recovery.
Therefore, the object of the present invention is to decompose the surfactant and use it as a nutrient source for energy recovery in methane fermentation etc. in a water treatment apparatus for biologically treating organic wastewater containing a high concentration of surfactant. Another object of the present invention is to provide a water treatment device capable of

As a result of intensive studies on the above problems, the present inventors found that when organic wastewater containing a high concentration of surfactant is subjected to anaerobic treatment, methane fermentation by methanogenic bacteria is suppressed, while surfactant The inventors have found that microorganisms that decompose the agent are activated and the concentration of the surfactant is lowered, thereby completing the present invention.
That is, the present invention is the following water treatment equipment.

A water treatment apparatus of the present invention for solving the above problems is a water treatment apparatus for treating organic wastewater containing a surfactant, wherein the surfactant is decomposed anaerobically. and an anaerobic treatment part provided after the surfactant decomposition part for anaerobically treating the organic wastewater.

According to this water treatment apparatus, two stages are provided for anaerobic biological treatment, and the first stage is formed with a surfactant decomposition section in which microorganisms that decompose surfactants are activated. Since the concentration of the surfactant in the decomposed liquid treated in the surfactant decomposing section is reduced, methane fermentation can be performed in the subsequent anaerobic processing section. As a result, it is possible to provide a water treatment apparatus for organic wastewater containing a high concentration of surfactant, which is excellent in energy recovery.

Furthermore, as one embodiment of the water treatment apparatus of the present invention, the concentration of the surfactant in the decomposition treatment liquid treated in the surfactant decomposition section is provided between the surfactant decomposition section and the anaerobic treatment section. and a density measuring unit for measuring the
According to this water treatment apparatus, since the concentration measuring unit for measuring the concentration of the surfactant is provided between the surfactant decomposition unit and the anaerobic treatment unit, the decomposition treated in the surfactant decomposition unit The surfactant concentration in the decomposition treatment liquid can be checked before the liquid is supplied to the anaerobic treatment section. Therefore, when the decomposition treatment liquid contains a high concentration of surfactant, it is necessary to stop the supply of the decomposition treatment liquid to the anaerobic treatment section so as not to destroy the growth environment of microorganisms in the anaerobic treatment section. can.

Furthermore, one embodiment of the water treatment apparatus of the present invention is characterized by comprising concentration adjusting means for adjusting the concentration of the surfactant contained in the decomposition treatment liquid.
According to this feature, since the concentration of the surfactant contained in the decomposition treatment liquid can be adjusted by the concentration adjusting means, even if the concentration of the surfactant in the decomposition treatment liquid is high, the microorganisms in the anaerobic treatment section The concentration can be adjusted to suit the growing environment of

Furthermore, as one embodiment of the water treatment apparatus of the present invention, the concentration adjusting means is a diluting means for diluting the decomposition treatment liquid.
According to this feature, the concentration of the surfactant in the decomposition treatment liquid can be adjusted to a concentration suitable for the growth environment of microorganisms in the anaerobic treatment section by a simple means.

Furthermore, one embodiment of the water treatment apparatus of the present invention is characterized by comprising an acid generator for adjusting pH or temperature in the preceding stage of the surfactant decomposing unit.
According to this feature, the acid-producing bacteria can produce lower fatty acids from solids such as sugars, proteins or oils and high-molecular weight organic substances, and the pH and temperature can be adjusted to the optimum conditions for the surfactant decomposition part. , can promote the decomposition of surfactants.

According to the present invention, in a water treatment apparatus for biologically treating organic wastewater containing a high concentration of a surfactant, the surfactant is decomposed and used as a nutrient source for energy recovery in methane fermentation or the like. can provide a water treatment device capable of

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of 1st embodiment of this invention. It is a graph showing the relationship between the sodium lauryl sulfate concentration and the activity of methanogens. 1 is a graph showing the relationship between sodium lauryl sulfate concentration and removal rate of chemical oxygen demand (CODCr). It is a schematic explanatory drawing which shows the structure of the water treatment apparatus of 2nd embodiment of this invention.

The water treatment apparatus of the present invention will be described below. It should be noted that the description of the water treatment apparatus of the present invention also discloses the corresponding water treatment method.

The water treatment apparatus of the present invention is used for organic wastewater containing a high concentration of surfactant as water to be treated. The concentration of the surfactant in the organic wastewater is not particularly limited, but is preferably over 200 mg/L, more preferably over 300 mg/L, and particularly preferably 400 mg/L. organic wastewater.

As the water to be treated, any organic wastewater containing a high concentration of surfactant may be used. , industrial wastewater from paper mills, textile factories, chemical factories, food factories, etc., and household wastewater containing detergents and the like.

The types of surfactants contained in organic wastewater inhibit the growth of microorganisms in the anaerobic treatment section. Anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants Either is fine.

Specific examples of anionic surfactants include alkyl sulfate esters such as sodium lauryl sulfate, potassium lauryl sulfate, ammonium lauryl sulfate, magnesium lauryl sulfate, monoethanolamine lauryl sulfate, sodium myristyl sulfate, sodium stearyl sulfate, and sodium oleyl sulfate. salt, POE (2) sodium lauryl ether sulfate, POE (3) sodium myristyl ether sulfate and other alkyl ether sulfate ester salts, potassium coconut oil fatty acid methyl taurate, sodium lauroyl methyl taurate and other N-acyl methyl taurate salts, coconut oil fatty acid N-acyl glutamate such as acyl glutamic acid, N-acyl methyl alanine salt such as sodium lauroyl methyl alanine, N-acyl sarcosinate such as sodium lauroyl sarcosinate, acyl lactate such as sodium stearoyl lactylate, potassium coconut oil fatty acid, lauric acid Fatty acid salts such as potassium and triethanolamine laurate are included. POE is an abbreviation for polyoxyethylene, and the numbers in parentheses indicate the number of added moles.

Specific examples of cationic surfactants include alkyl quaternary ammonium salts such as lauryltrimethylammonium chloride, stearyltrimethylammonium bromide, and dicocoyldimethylammonium chloride; amine salts such as dimethylstearylamine and diethylaminoethylamide stearate; etc.

Specific examples of amphoteric surfactants include amino acid-type amphoteric surfactants such as sodium lauryldiaminoethylglycine and sodium laurylaminopropionate, coconut oil alkylbetaine, betaine lauryldimethylaminoacetate, laurylhydroxysulfobetaine and the like. Examples include betaine amphoteric surfactants.

Specific examples of nonionic surfactants include polyoxyethylene alkyl ethers such as POE lauryl ether and POE cetyl ether, glycerin fatty acid esters such as glyceryl monostearate, and sorbitan fatty acid esters such as sorbitan monolaurate. .

From the viewpoint of high inhibitory activity against anaerobic microorganisms, anionic surfactants are preferred, alkyl sulfate ester salts are more preferred, and sodium lauryl sulfate is particularly preferred.

A water treatment apparatus of the present invention is a water treatment apparatus for treating organic wastewater containing a surfactant, comprising: a surfactant decomposition section for anaerobically decomposing the surfactant; and a surfactant decomposition section. and an anaerobic treatment unit that is provided in the latter stage of and anaerobically treats the organic wastewater.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that this embodiment does not limit the present invention.
[First embodiment]
FIG. 1 is a schematic explanatory diagram showing the structure of a water treatment apparatus 1A according to the first embodiment of the present invention. The water treatment apparatus 1A is an anaerobic treatment apparatus for anaerobically treating the water W0 to be treated with anaerobic microorganisms, and includes an acid generation section 2, a surfactant decomposition section 3, and an anaerobic treatment section 4. FIG. Organic wastewater containing a high concentration of surfactant is used as the water to be treated W0.
The acid-producing part 2 is a structure for producing lower fatty acids from solids such as sugars, proteins, oils, and high-molecular organic substances by acid-producing bacteria.
The surfactant decomposition unit 3 is configured to decompose the surfactant contained in the organic wastewater. processing.
The anaerobic treatment unit 4 is configured to perform methane fermentation using the organic matter decomposed by the acid generation unit 2 and the surfactant decomposition unit 3 . The acid generation tank 2, the surfactant decomposition section 3, and the anaerobic treatment section 4 are all in an anaerobic state.

(acid generator)
The acid generator 2 is provided with a pipe for supplying the water W0 to be treated, and organic waste water containing a high concentration of surfactant is supplied as the water W0 to be treated. In the acid-producing section 2, the acid-producing bacteria not only produce lower fatty acids from solids such as sugars, proteins, or oils, and high-molecular-weight organic substances, but also the water to be treated W0 is subjected to biological treatment in the surfactant-decomposing section 3 in the latter stage. A suitable environment can be arranged.

In the acid generator 2, the pH is adjusted to 6-9, preferably 6-8, more preferably 6.5-7.5. The pH can be adjusted by adding a pH adjuster such as acid or alkali. Also, the temperature is adjusted to 25 to 40°C, preferably 30 to 40°C, more preferably 35 to 38°C. As a result, the growth of the anaerobic microorganism treatment in the surfactant decomposition section 3 in the latter stage is stabilized, and the decomposition of the surfactant is promoted.

(Surfactant decomposition part)
The surfactant decomposition unit 3 is supplied with the organic wastewater whose pH and temperature have been adjusted by the acid generation unit 2, and the surfactant is decomposed by the action of anaerobic microorganisms. Microorganisms that decompose surfactants (hereinafter referred to as "surfactant-degrading bacteria") continue to supply water to be treated W0 containing a high concentration of surfactants when anaerobically treating activated sludge. It proliferates naturally. By growing the surfactant-decomposing bacteria thus obtained, the concentration of the surfactant in the water W0 to be treated can be reduced. The exhaust gas generated by the surfactant decomposition section 3 is used together with the biogas G in the anaerobic treatment section 4 .

The state of surfactant-decomposing bacteria may be in any state, for example, they may be dispersed as sludge in organic wastewater, or surfactant-decomposing bacteria may be retained on the surface of a carrier such as a fixed bed or fluidized bed. It may also be used as a microorganism-immobilizing carrier.

Although the amount of the surfactant decomposed in the surfactant decomposing unit 3 is not specified, the concentration of the surfactant is preferably 400 mg/L or less, more preferably 300 mg/L or less, still more preferably 200 mg/L or less, and more preferably 200 mg/L or less. It is more preferably decomposed to 100 mg/L or less, particularly preferably 50 mg/L. As a result, the activity of methanogenic bacteria in the subsequent anaerobic treatment section is rapidly increased, and the chemical oxygen demand (CODCr) in the treated water is reduced.

A portion of the organic wastewater that has been treated in the surfactant decomposition section 3 or the organic wastewater that is being treated may be recycled to the acid generation section 2 . As a result, even if the pH of the water to be treated W0 supplied to the acid generator 2 fluctuates greatly, the water to be treated W0 is diluted by the circulating water W2, so that the acid-producing bacteria in the acid generator 2 do not grow. It has a stabilizing effect.

(Anaerobic treatment section)
The anaerobic treatment unit 4 is configured to anaerobically treat the organic wastewater in which the surfactant concentration has been reduced in the surfactant decomposition unit 3. Specifically, methane fermentation is performed by methanogenic bacteria. , to generate methane as biogas G. The treated water W1 subjected to methane fermentation is discharged outside the system.

The state of methanogens in the anaerobic treatment unit 4 may be any state. For example, the methanogens may be dispersed as sludge in organic wastewater, or the methanogens may be retained on the surface of a carrier such as a fixed bed or fluidized bed. It may be a microorganism-immobilizing carrier, or may be in the form of granule sludge. It is preferable to use a fixed bed, carrier, or granular sludge, and it is particularly preferable to use granular sludge, from the viewpoint of excellent methane production ability.

Next, FIG. 2 and FIG. 3 show data obtained by obtaining the relationship between the surfactant concentration in organic wastewater, the activity of methanogens, and the removal rate of chemical oxygen demand (CODCr).
FIG. 2 is a graph showing the relationship between sodium lauryl sulfate concentration and methanogen activity, and FIG. 3 is a graph showing the relationship between sodium lauryl sulfate concentration and chemical oxygen demand (CODCr) removal rate. is.
In this test, organic wastewater to which a predetermined amount of sodium lauryl sulfate was added was used as the water to be treated. In addition, the activity of methanogenic bacteria was calculated by performing an acetic acid assimilation test (batch test) using granules and setting the case where sodium lauryl sulfate was not added to be 100%.

As shown in FIG. 2, the activity of methanogens increased sharply at concentrations of sodium lauryl sulfate of 400 mg/L or less, and reached 100% at concentrations of 50 mg/L or less.
Further, as shown in FIG. 3, the removal rate of chemical oxygen demand (CODCr) sharply increased when the concentration of sodium lauryl sulfate was 400 mg/L or less, and became almost constant when the concentration was 200 mg/L or less.
That is, from the viewpoint of improving the activity of methanogens, the concentration of the surfactant is particularly preferably 50 mg / L or less, and from the viewpoint of improving the removal rate of chemical oxygen demand (CODCr), It can be said that the surfactant concentration is particularly preferably 200 mg/L or less.

Further, in the water treatment apparatus 1A of the first embodiment, the pipe connecting the surfactant decomposition section 3 and the anaerobic treatment section 4 is provided with a concentration measurement section D for measuring the concentration of the surfactant. As shown in the above data, when the concentration of the surfactant exceeds 400 mg/L, the activity of methanogens is significantly reduced, so it is necessary to strictly control the concentration of the surfactant in the anaerobic treatment unit 4. . By providing the concentration measurement unit D, it is possible to prevent the organic wastewater containing a high concentration of surfactant from flowing into the anaerobic treatment unit 4 .

The concentration measurement unit D may be installed at any position as long as it is in front of the anaerobic treatment unit 4. However, the surfactant decomposition unit 3 immediately before the anaerobic treatment unit 4, the surfactant decomposition unit 3 and the anaerobic It is preferable to install it in a pipe connecting the processing units 4 .

In the concentration measurement part D, the concentration of the surfactant may be measured using a measuring instrument or the like, or a part of the organic wastewater may be sampled as a measurement sample and the concentration of the surfactant may be measured for the measurement sample. good.

The method for measuring the concentration of the surfactant is not particularly limited. If it is a nonionic surfactant, it is measured by "Determination of nonionic surfactant by tetrathiocyanatocobalt(II) acid absorption photometry" (JIS K 0102 30.2.1). In the case of cationic surfactants and amphoteric surfactants, "Analysis of cationic-amphoteric binary surfactants Orange II method" (Kogyo Kagaku Zasshi, Vol. 66, No. 10, 1963, 1449- 1451).

Furthermore, it is preferable to provide concentration adjusting means for adjusting the concentration of the surfactant. Concentration adjustment means include, for example, diluting means for supplying clean water, treated water from other facilities, organic wastewater, etc. to dilute the decomposition treatment liquid, and addition of a flocculating agent to flocculate the surfactant to precipitate and separate. Examples include means for removing the surfactant by means of a solvent, means for separating the surfactant by means of an adsorbent that adsorbs the surfactant, and the like. It is particularly preferable to provide a diluting means for reasons such as being able to respond quickly to changes in the concentration of the surfactant and being easy to work with.
By providing the concentration adjusting means, even when the concentration of the surfactant in the decomposition treatment liquid processed in the surfactant decomposition section 3 is high, the supply to the anaerobic processing section 4 is not stopped, and the anaerobic processing section 4 It is possible to maintain the activity of the methanogen at a high level.

The concentration of the surfactant adjusted by the concentration adjusting means is preferably 400 mg/L or less, more preferably 300 mg/L or less, still more preferably 200 mg/L or less, and even more preferably, similar to the surfactant decomposition section 3. is 100 mg/L or less, particularly preferably 50 mg/L. As a result, the activity of methanogenic bacteria in the subsequent anaerobic treatment section and the removal rate of chemical oxygen demand (CODCr) in the treated water can be maintained at a high level.

The concentration adjustment of the surfactant by the concentration adjusting means may be performed by a control device controlled by the input of the signal from the concentration measuring section D. For example, in the case of concentration adjustment by the dilution means, it is possible to control so as to adjust the flow rate of the dilution water according to the measurement result from the concentration measuring section D.
Alternatively, the amount of diluent water to be supplied may be calculated from the measured value of the concentration measuring section D, and the flow rate of the diluent water may be adjusted artificially.

[Second embodiment]
FIG. 4 shows the structure of a water treatment device 1B according to the second embodiment of the present invention. In the second embodiment, a concentration measurement unit D is provided in the surfactant decomposition unit 3, and tap water or industrial water W3 is supplied to the pipe connecting the surfactant decomposition unit 3 and the methane fermentation tank 4 as concentration adjustment means. is provided with dilution means for supplying the According to this water treatment apparatus 1B, even when the concentration of the surfactant in the decomposed water treated in the surfactant decomposing unit 3 is high, it is diluted by the diluting means. Growth can be maintained.

The water treatment apparatus of the present invention is used for organic wastewater containing a high concentration of surfactant as water to be treated.
As the water to be treated, any organic wastewater containing a high concentration of surfactant may be used. , paper mills, textile factories, chemical factories, food factories, etc., and domestic wastewater containing detergents and the like.

DESCRIPTION OF SYMBOLS 1A, 1B... Water treatment apparatus, 2... Acid generation part, 3... Surfactant decomposition part, 4... Anaerobic treatment part, 5A, 5B, 5C, 5D... Dilution means, W0... Water to be treated, W1... Treated water, W2... circulating water, W3... tap water or industrial water, G... biogas

Claims (6)

A water treatment apparatus for treating organic wastewater containing surfactants, comprising:
a surfactant decomposition unit that anaerobically decomposes the surfactant;
an anaerobic treatment unit provided downstream of the surfactant decomposition unit for anaerobically treating the organic wastewater by methane fermentation;
an acid generation unit provided upstream of the surfactant decomposition unit ;
A water treatment apparatus comprising a circulation unit for circulating part of the organic wastewater treated in the surfactant decomposition unit or the organic wastewater being treated to the acid generation unit. a concentration measurement unit provided between the surfactant decomposition unit and the anaerobic treatment unit for measuring the concentration of the surfactant in the decomposition treated liquid treated by the surfactant decomposition unit. 2. A water treatment system according to claim 1, characterized in that: 3. The water treatment apparatus according to claim 2, further comprising concentration adjusting means for adjusting the concentration of the surfactant contained in said decomposition treatment liquid. 4. The water treatment apparatus according to claim 3, wherein said concentration adjusting means is a diluting means for diluting said decomposition treatment liquid. A water treatment apparatus for treating surfactants in organic wastewater, comprising:
a surfactant decomposition unit that anaerobically decomposes the surfactant in the organic wastewater treated by the acid generation unit;
anaerobically treating the organic wastewater treated in the surfactant decomposition unit by methane fermentation ;
A water treatment apparatus characterized in that part of the organic wastewater treated in the surfactant decomposing section or the organic wastewater being treated is circulated to the acid generating section. A water treatment method for treating surfactants in organic wastewater, comprising:
Acidogenic Treated Organicwasteanaerobically decomposing the surfactant in water;
Anaerobic treatment of decomposed organic wastewater by methane fermentationdeath,
A portion of the organic wastewater that has been decomposed or is being treated is recycled to the acid generation treatment.A water treatment method characterized by:

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