JPH11689A - Organic wastewater treatment equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] An organic material capable of subjecting an organic wastewater containing a sulfur compound to high-load anaerobic treatment and applying a compact biofilm filtration device as post-treatment of anaerobic treatment. Provide a wastewater treatment device. SOLUTION: An organic acid generating tank 1 into which an organic wastewater containing a sulfur compound is introduced, degassing means 2 for degassing hydrogen sulfide generated in the organic acid generating tank 1, and a liquid from which hydrogen sulfide is degassed An organic wastewater treatment apparatus, comprising: a methane production tank 3 into which water is introduced; and a biofilm filtration device 4 into which an effluent from the methane production tank 3 is introduced. [Effect] Since hydrogen sulfide generated in the organic acid generation tank 1 is degassed and then sent to the methane generation tank 3, the inhibition of the activity of methane-producing bacteria due to hydrogen sulfide is prevented, and high-load processing can be performed. Further, since the generation of colloidal sulfur is also prevented, the biofilm filtration device 4 can be applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the treatment of organic wastewater such as food processing wastewater, petroleum refinery wastewater, municipal sewage and domestic wastewater including human waste containing sulfur compounds such as sulfate ions, sulfite ions and sulfur-containing amino acids. Related to the device.

[0002]

2. Description of the Related Art Currently, wastewater treatment apparatuses are required to have a high load, a small area, and compactness.
(Upflow Anaerobic Sludge Blanket; Upflow anaerobic sludge bed) 15
A high-load anaerobic treatment method capable of applying kg / m ³ · day or more is applied to many wastewater treatments.

[0003]

However, even with these high-load anaerobic treatment methods, high-load treatment is difficult in wastewater containing a large amount of sulfur compounds such as sulfate ions, sulfite ions, and sulfur-containing amino acids. In addition, there is a problem that a sedimentation tank is not required as a post-treatment device for anaerobic treatment, and a biofilm filtration device excellent in compactness cannot be used.

The causes of this problem can be roughly classified into the following two points.

Problems at the Stage of Anaerobic Treatment Sulfur compounds in wastewater are reduced to hydrogen sulfide by sulfuric acid reducing bacteria in the anaerobic treatment device, and the activity of methanogens in the anaerobic reaction tank is reduced by the hydrogen sulfide. Is inhibited. In particular, in a high-load treatment in which the load is increased to 15 kg-BOD / m ³ · day or more, the concentration of hydrogen sulfide in the liquid in the reaction tank is 1%.
When it reaches 00 mg / L or more, the activity of the methanogen may be halved. Therefore, it is difficult to perform high-load treatment on wastewater containing a large amount of sulfur compounds. Problems arising from post-treatment biofilm filtration Some of the hydrogen sulfide generated during the anaerobic treatment stage is contained in the digested gas generated, but the remaining hydrogen sulfide is dissolved in the anaerobic treated water and post-treated. Into the biofilm filtration device.
The inflowing hydrogen sulfide generates colloidal sulfur before being oxidized by sulfur bacteria such as thiobacillus, thiobacterium, and veggiator in biofilm sludge in the biofilm filtration device to form sulfur ions. Due to the colloidal sulfur, the treated water becomes cloudy and the quality of the treated water deteriorates. In addition, a large amount of biofilm sludge containing colloidal sulfur and sulfur-oxidizing bacteria is generated, which promotes clogging of the packing material of the biofilm filtration device, and greatly increases the frequency of backwashing. In addition, at the time of sludge treatment of backwash wastewater, sludge containing colloidal sulfur is hard to coagulate,
In a dehydrator using a filter cloth such as a belt press, clogging of the filter cloth is likely to occur, and dehydration processing becomes difficult.

[0006] For this reason, high-load anaerobic treatment is possible even in wastewater containing a large amount of sulfur compounds, and a treatment system that does not generate colloidal sulfur in a post-treatment biofilm filtration device. Development is requested.

The present invention has been made in view of the above-mentioned conventional situation, and is capable of performing high-load anaerobic treatment of organic wastewater containing a sulfur compound, and having a compact biological wastewater as a post-treatment for anaerobic treatment. An object of the present invention is to provide an organic wastewater treatment apparatus to which a membrane filtration device can be applied.

[0008]

According to the present invention, there is provided an organic wastewater treatment apparatus comprising: an organic acid generating tank into which an organic wastewater containing a sulfur compound is introduced; and a hydrogen sulfide generated in the organic acid generating tank. And a methane production tank into which the liquid from which hydrogen sulfide has been degassed is introduced, and a biofilm filtration device into which the effluent from the methane production tank is introduced.

The anaerobic reaction is roughly classified into an organic acid-forming reaction and a methane-forming reaction. In the organic acid reaction, organic substances are liquefied and depolymerized under anaerobic conditions by organic acid-producing bacteria or sulfate-reducing bacteria, and carbohydrates are produced. Is decomposed into lower fatty acids such as formic acid, acetic acid, propionic acid and butyric acid, and proteins are decomposed into amino acids. In addition, sulfur compounds in the wastewater are reduced to hydrogen sulfide by sulfate reducing bacteria. Therefore, when the organic acid generation reaction is sufficiently performed, the sulfur compounds in the wastewater are reduced to hydrogen sulfide, and a part of the generated hydrogen sulfide is contained in the gas generated during the organic acid reaction. Many hydrogen sulfides dissolve in the liquid and are contained in the effluent of the organic acid production tank and flow into the subsequent methane production tank to inhibit the activity of methanogens and to form colloids in the biofilm filtration device. It becomes sulfur and causes various obstacles.

In the present invention, hydrogen sulfide generated in the organic acid generating tank is degassed and then sent to the methane generating tank, so that the activity of methane-producing bacteria is not inhibited by hydrogen sulfide and high-load processing can be performed. Become. Further, since the generation of colloidal sulfur is also prevented, the biofilm filtration device can be applied.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of an organic wastewater treatment apparatus according to the present invention, and FIG. 2 is a system diagram showing a preferred example of a hydrogen sulfide deaerator.

In the present invention, an organic wastewater containing a sulfur compound is first introduced into an organic acid producing tank 1, and organic substances in the wastewater are liquefied and depolymerized under anaerobic conditions by an organic acid producing bacterium or a sulfate-reducing bacterium to produce sugar. Decomposes into lower fatty acids and protein into amino acids and reduces sulfur compounds to hydrogen sulfide.

The effluent of the organic acid generating tank 1 is introduced into a hydrogen sulfide degassing device 2 to degas hydrogen sulfide in the liquid. The liquid from which hydrogen sulfide has been degassed is then introduced into the methane production tank 3 and the organic acids in the liquid are decomposed to methane under anaerobic conditions by methane producing bacteria.

The influent of the methane production tank 3 has been subjected to hydrogen sulfide removal by the hydrogen sulfide deaerator 2 to reduce the concentration of hydrogen sulfide. Therefore, high load processing is possible.

The effluent from the methane production tank 3 is then introduced into a biofilm filtration device 4 for biological treatment and filtration. In this biofilm filtration treatment, since the concentration of hydrogen sulfide in the influent of the biofilm filtration device 4 is low, the amount of colloidal sulfur generated is extremely small, and the quality of the treated water is reduced by the colloidal sulfur and the clogging of the filler is prevented. You.

In the present invention, the degassing of the hydrogen sulfide generated in the organic acid generating tank 1 is performed by closing the effluent of the organic acid generating tank 1 containing hydrogen sulfide while keeping the effluent out of contact with air. Water is sprayed on a degassing device of the type, and the digestion gas mainly composed of methane gas and carbon dioxide gas generated from the methane generation tank 3 is collected in the gas holder 5 and a part thereof is blown, and the digestion gas flows out of the organic acid generation tank 1. While aerating the liquid, for example-
It is preferable to perform the deaeration by suction under a reduced pressure of 400 mmHg or less. By performing such a deaeration, hydrogen sulfide in the liquid can be gasified and removed from the liquid. At this time, by adjusting the pH of the effluent of the organic acid generation tank 1 to the acidic side, the efficiency of degassing and removing hydrogen sulfide can be further increased. In addition, not only decompression degassing but also nitrogen degassing,
It is also possible to use vacuum degassing or the like.

The gas containing hydrogen sulfide obtained by suction and degassing in the hydrogen sulfide degassing device 2 is obtained by using a digestion gas from the methane production tank 3 together with a wet desulfurization device using an alkali solution or an iron oxide. Gas is passed through a desulfurizer 6 such as a dry desulfurizer to perform desulfurization.

In the structure or specification of the above-mentioned closed type deaerator, it is necessary to pay attention to the selection of the filler to be installed therein and the installation method. That is, since the effluent of the organic acid generating tank 1 contains organic acid generating bacteria and sulfate-reducing bacteria, and furthermore, SS in the wastewater, the filler installed in the deaerator has a structure or specifications that are not easily blocked, and When closed, it is required that the structure be such that it can be easily washed in a sealed state.

FIG. 2 shows a preferred example of such a deaerator.

The deaerator 10 is a tower-type multi-stage wet wall system, in which three to five (four in FIG. 2) wet walls 11 inclined at 10 to 30 degrees are alternately provided inside the tower. is set up. At the top of the tower, there is an introduction pipe 12 for the effluent of the organic acid generation tank.
Is provided, and this effluent is sprayed. A treated water receiving tank 13 having a water depth of 500 to 1000 mm is provided at the bottom of the tower,
Aeration is performed by the gas diffuser 14 in the receiving tank 13 with the digestion gas from the methane generating tank. An intake pipe 15 is provided above the tower, and the inside of the tower is depressurized by a suction depressurizing blower 16. The treated water in the receiving tank 13 is supplied from a pipe 17 to a pump 18.
And sent to the methane production tank.

In such a deaerator 10, since there is no place where SS and anaerobic sludge are deposited, there is no fear that the wet wall 11 is blocked. Even if SS or sludge accumulates on the wet wall 11, it can be easily washed and removed by squirting the pressurized water at the intersections of the wet wall 11 that are alternately combined.

The processing performance of the deaerator 10 of the present system varies depending on the amount of liquid passing through the wetting wall 11, the degree of pressure reduction of the suction decompression blower 16, the amount of digestion gas aerated from the lower part of the tower, the pH of the liquid passing, and the like. Therefore, the operation at the time of the actual operation is only required to adjust the blowing amount of the digestion gas and the degree of decompression of the suction decompression blower 16, and the operation is easy. As the suction depressurizing means, the pressure in the tower is -40.
As long as it is a completely hermetic structure capable of reducing the pressure to 0 mmHg or less, not only blowers but also various gas suction pumps and ejectors can be used.

In this embodiment, the digestion gas blown into the degassing device 10 is the digestion gas from the methane production tank that has not been subjected to the desulfurization treatment, but the digestion gas that has been subjected to the desulfurization treatment is further used. The degassing effect of hydrogen sulfide can be enhanced. In addition, the injection of the digestion gas is not essential.For example, when the concentration of hydrogen sulfide in the effluent of the organic acid generation tank is relatively low and it is not necessary to increase the amount of hydrogen sulfide removed by the deaerator, the pressure in the column is reduced. It is only necessary to aspirate, and there is no need to blow the digestion gas.

In the present invention, such degassing means
The hydrogen sulfide concentration in the liquid introduced into the methane production tank 3 is 50 m
It is preferable to remove hydrogen sulfide so as to be not more than g / L.

In the present invention, the organic acid generation tank is not particularly limited, and a fixed-bed type in which a plastic filler is installed in the tank, or gas stirring or mechanical stirring in the tank using floating sludge. Various types and structures, such as a typical anaerobic digester system, can be applied.

The methane production tank is not particularly limited, and a fixed bed system, a UASB system, a fluidized bed system, or a general anaerobic digestion tank system using suspended anaerobic sludge can be employed.

There is no particular limitation on the biofilm filtration device.
A filler filled with a filler having a particle size of about 2 to 50 mm can be used.

According to the apparatus for treating organic waste water of the present invention, the concentration in terms of SO ₄ ion is 1000 to 3000 m.
Even organic wastewater containing a sulfur compound at a relatively high concentration of about g / L, 10 to 10 sludge volume per methanation tank.
It can be processed at a high load operation of 15 kg-BOD / m ³ · day.

[0030]

The present invention will be described more specifically below with reference to examples and comparative examples.

Example 1 An organic acid generation tank was provided before a methane generation tank, and a BOD concentration of 2
000-3500 mg / L, SO ₄ ion concentration 800-
A continuous test was performed by applying the method of the present invention using a part of the treated water of an actual apparatus in which anaerobic treatment of 1100 mg / L of sugar refinement wastewater was performed by the UASB method.

That is, the organic acid generation tank (capacity 150
A part of the effluent of 0 m ³ ) was subjected to hydrogen sulfide removal by a test deaeration treatment apparatus (capacity: 135 L) having the configuration shown in FIG. 2 and a UASB anaerobic methane production tank (sludge holding capacity of 1) was used for the test.
25 L), and the treated water was treated with a test biofilm filtration device (filler capacity 125 L).

The main specifications and operating conditions of each test apparatus used are as follows.

(1) Degassing device for removing hydrogen sulfide for testing The degassing tower is made of transparent vinyl chloride having a length and width of 30 cm and a height of 150 cm, and has a wet wall with an inclination angle of 20 to 30 degrees inside.
It was installed in four steps at 0 cm intervals. The opening near the intersection of each wet wall was 10 cm or more. At the bottom of the degassing tower is provided deaerated water receiving tank of water depth 30 cm, the received digestion gas (gas composition generated from UASB anaerobic treatment apparatus of the real device in a tank CH ₄ 63~72%, CO ₂ 28-3
7%, more sparge tube the H ₂ S 0.1~0.3%) LV1
Blowing was performed at 0 m / hr (gas flow rate 15 L / min).
A closed type air pump was installed above the degassing tower, and the suction amount of the air pump was adjusted so that the pressure inside the degassing tower became -400 mmHg. A part of the effluent of the organic acid generation tank of the actual apparatus was sprinkled from the upper part of the uppermost wet wall in the degassing tower, and the treated water was discharged from the lower receiving tank. The effluent (soluble H ₂ S) of the organic acid generation tank is supplied to the deaerator having such specifications and operating conditions.
When the concentration 170~270mg / L) was passed through at 100L / hr, solubility concentration of _{H 2} S in the deaerator treated water 2
It was reduced to 5-33 mg / L.

(2) A gas / liquid / sludge separator (GSS) was installed above the UASB anaerobic methane production tank for testing.
An anaerobic sludge taken out of the actual apparatus is put into a UASB reaction tank made of transparent vinyl chloride having a diameter of 40 cm and a height of 200 cm, and a capacity of 125 L (filled bed height: 100 cm) is put into the anaerobic sludge. (Residence time 4 hours per volume). BOD of effluent of deaerator is 2
200 to 3250 mg / L, and the load of the test methane production tank was 13.2 to 19.5 k per sludge volume.
It was a high-load operation of g-BOD / m ³ · day. The pH of the liquid in the test methane production tank was 7.0 to 7.3 as in the actual apparatus, and the water temperature of the liquid in the tank was 3 as in the actual apparatus.
Adjusted to 5-38 ° C. The BOD of the treated water in the test methane production tank is 180 to 250 mg / L, and the UASB of the actual device which operates with a relatively small load of 5 to 8.8 kg-BOD / m ³ · day per sludge volume. BOD (166-280 m) of the effluent from the methane production tank of the reactor
g / L).

(3) Biofilm Filtration Device for Testing Anthracite having a particle size of 3 to 4 mm was placed in a transparent vinyl chloride column having a diameter of 40 cm and a height of 200 cm at a height of 10 cm.
Biofilm filtration test device filled to 0 cm (filler capacity 12
5 L) at a flow rate of 31 L / hr (residence time 4 hours per filler volume). The water was passed from the lower part of the biofilm filtration device, and the treated water was discharged from the upper part. Aeration was performed from the lower part of the biofilm filtration device, and the concentration of dissolved oxygen in the treated water was set within the range of 2 to 3 mg / L by adjusting the amount of aeration air. Continuous operation was performed for 14 days using the test devices having these specifications, and the quality of the treated water from the biofilm filtration device and the pressure loss generation rate of the filler of the biofilm filtration device were examined. The results are shown in Table 1.

Comparative Example 1 In Example 1, the UASB anaerobic treatment device (capacity: 250) of the actual device was used instead of the effluent of the organic acid production tank of the actual device.
0 m ³ ) of treated water (that is, effluent of a methane production tank), and treated in the same manner except that this treated water was directly treated with a biofilm filtration device for testing. In addition, the rate of pressure loss generation of the filler in the biofilm filtration device was examined, and the results are shown in Table 1.

[0038]

[Table 1]

As is clear from Table 1, according to the present invention, the quality of the treated water is improved and the pressure loss generation rate of the filler is significantly reduced as compared with the conventional method.

[0040]

As described above in detail, according to the organic wastewater treatment apparatus of the present invention, high load operation of anaerobic treatment (methane production tank) becomes possible. The generation of colloidal sulfur in the biofilm filtration device can be prevented, and more advanced treated water can be obtained. The increase in pressure drop of the biofilm filtration device is reduced, and the frequency of backwashing is reduced. Furthermore, it is possible to effectively apply an area-saving and compact biofilm filtration device to the post-treatment of the anaerobic treatment device, and the whole treatment system becomes compact. Effectively treats organic wastewater such as food processing wastewater, oil refinery wastewater, city sewage, domestic wastewater including human waste including sulfur compounds such as sulfate ions, sulfite ions, and sulfur-containing amino acids. High quality treated water can be obtained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an organic wastewater treatment apparatus of the present invention.

FIG. 2 is a system diagram showing a preferred embodiment of a hydrogen sulfide deaerator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Organic acid generation tank 2 Hydrogen sulfide degassing device 3 Methane generation tank 4 Biofilm filtration device 5 Gas holder 6 Desulfurization device 10 Degassing device 11 Wet wall 13 Receiving tank 14 Air diffuser 16 Suction depressurizing blower

Claims (1)

[Claims] 1. An organic acid generating tank into which an organic wastewater containing a sulfur compound is introduced, a degassing means for degassing hydrogen sulfide generated in the organic acid generating tank, and a liquid from which hydrogen sulfide has been degassed. An organic wastewater treatment apparatus, comprising: a methane production tank to be introduced; and a biofilm filtration device to which an effluent of the methane production tank is introduced.