JPH11179387A - Carrier for biological treatment of waste water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier consisting of a hydrophobic member, to which microorganisms can adhere, which can be carried on a water current to rotationally move simultaneously with a startup of a biological treatment without waiting for the adhesion of microorganisms, and which can maintain the rotational movement for a long time, by supporting lignin on a wet surface of the carrier to have such wettability as bubbles hardly adhere. SOLUTION: Carriers 1 consist of a hydrophobic member made of porous polyurethane foam which is a rectangular parallelepiped 6 mm square, and are formed by constituting the wet surfaces of the carriers 1 in such a way that they support lignin to give such wettability as bubbles hardly adhere. Biological treatment equipment is provided with an element 12 for preventing outflow of the carrier installed in a lower part of a reaction tank 10. The element 12 for preventing outflow of the carriers is composed of a hard water-permeable plate body, such as a net body, whose mesh size is smaller than the carriers 1 to prevent the outflow of the carriers 1. The reaction tank 10 is constituted in such a manner that an air diffusion pipe 13 is connected to a blower 14, an aeration operation is carried out by pressure of air jetting out from the air diffusion pipe 13, and the carriers 1 in the tank are carried on the flow of an liquid in the tank to rotationally move in water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carrier useful for biologically treating organic substances contained in wastewater such as domestic wastewater or industrial wastewater by a carrier fluidized bed. For the biological treatment of wastewater useful for decomposing in a known batch type or continuous type biological reaction tank of a driving type, an aerobic state and an anaerobic state alternately and repeatedly operating, and other various types. Carrier.

[0002]

2. Description of the Related Art When organic matter in wastewater is decomposed with microorganisms, it is very important how to effectively flow a carrier to which microorganisms adhere. For example, many sponge-like carriers are hydrophobic, so they do not adapt to the internal solution even if they are put into the microbial reaction tank as they are, keep floating on the water surface, and do not settle and rotate until microorganisms adhere. . Also,
Even if the water is immersed while removing the air bubbles, the aeration operation in the reaction tank causes the air bubbles to adhere to the carrier again, and the carrier floats on the water surface. Although the flow in the closed state is obtained, the effective rotation of the carrier circulating in the water does not occur.

[0003] Therefore, a hydrophobic sponge-like carrier such as polyurethane is hydrophilized with an alcohol or a carrier wettability improver, or water or a mixture of biological sludge is absorbed and then charged into a biological reaction tank. Japanese Patent Publication No. 4-55757 and Japanese Unexamined Patent Publication No. 9-57288 disclose a method of turning the rotation by taking care of it. However, it is difficult to absorb the biological sludge mixture in facilities where it is difficult to prepare the biological sludge mixture. In addition, the method of including water in the carrier and the submergence with alcohol are effective only during treatment, that is, only in an existing wastewater biological treatment facility, or in a new case, a facility into which wastewater flows in immediately after the introduction of the carrier.
In mere water, the carrier circulates only immediately after the start of the aeration operation, but within a few hours or even one day, bubbles generated by the aeration adhere to the carrier and the carrier floats on the water surface. That is, the rotation does not occur. This is because even if the carrier has a specific gravity of 1 or more, bubbles adhere to the carrier, and as a result, the carrier appears as a result of the apparent specific gravity being lower than 1. In this regard, in the case of wastewater, as time passes, microorganisms begin to adhere to the surface of the hydrophobic carrier and become hydrophilic, so that the carrier gradually increases the wettability, so that bubbles hardly adhere to the tank. Although it is circulated inside, it keeps floating until microorganisms adhere to the carrier and become hydrophilic, so that effective rotation during that time cannot be obtained.

The inventor of the present application has focused on surfactants for imparting hydrophilicity to a carrier. Examples of the surfactant include, for example, commonly used kitchen detergents (for example, Kao Corporation) containing polyoxyethylene alkyl ether, sodium alkyl ether sulfate, fatty acid alkanolamide, and alkylamine oxide as components. ), Family Fresh, etc.)
In addition, non-ionic, alkyl allyl ether type polyoxyethylene nonylphenyl ether,
Alkyl ether type polyoxyethylene lariul ether, anionic sulfonate type sodium dialkyl sulfo succinate, sulfate type sodium polyoxyethylene nonylphenyl ether sulfate, sodium Polyoxyethylene tridecyl ether sulfate,
Non-ionic, anionic (sulfonate,
Carboxylate), cationic (quaternary ammonium salt)
Examples include polyethylene glycol used as an intermediate in synthesizing amphoteric (betaine) and a surfactant, and a nonionic polyglycol-based polymer compound. Further, Ripal 870P (trade name, manufactured by Lion) , Liponox NC-100 (trade name, manufactured by Lion), Rex OT-P (trade name, manufactured by Kao), Rex NBL
(Trade name, manufactured by Kao). However, when these surfactants are supported on a hydrophobic sponge-like carrier such as polyurethane and subjected to hydrophilization treatment, the treated carrier is treated in the same manner as in the method of including water in the carrier and hydrophilization with alcohol. Into the water and start aeration, the carrier is circulating for a while, but within a few hours or even one day, as the bubbles generated by the aeration adhere to the carrier, Appeared on the water surface, and it was confirmed that the circulation of the carrier was hindered. For example, sodium dialkyl
When a 6 mm square rectangular polyurethane foam is placed on a 10 g / l aqueous solution of sulfo succinate, it is submerged within one minute and becomes hydrophilic. However, when the carrier that has been hydrophilized is put into a water tank filled with water and aeration is performed, the carrier is circulating for a while, but the aerated air bubbles gradually adhere to the carrier, and with this, The carrier floats on the surface of the water,
After all, circulation of the carrier cannot be expected.

[0005] The inventor of the present invention carried out an experiment in which lignin was carried on a member, such as polyurethane, acrylic, polyethylene, polypropylene, or polyvinyl chloride, which was difficult to rotate due to air bubbles attached thereto. However, it has been found that hydrophilicity is imparted, bubbles are hard to adhere, and it is easy to rotate.And, regarding the relationship between the shape of the carrier and the adhesiveness of the bubbles, a foam-like or tube-ring-like shape is used. Experiments were conducted with various shapes such as granular shapes, and it was found that bubbles easily adhered to any shape and easily rotated, and the present invention was completed.

[0006]

The first problem to be solved is that, first of all, it is possible to turn on the water flow simultaneously with the start of the biological treatment operation without waiting for the attachment of microorganisms, and this state is long. A carrier for biological treatment of wastewater that is
A second object of the present invention is to provide a biological treatment carrier for wastewater which can be set in a state where it can be immediately settled in water and turned so as to be put into a tank.

[0007]

According to the present invention, in order to achieve the above object, lignin is carried on a wet surface of a carrier made of a hydrophobic member to which microorganisms can adhere, and the wet surface has a bubble attached thereto. It is characterized by having poor wettability. Further, the present invention is characterized in that the carrier is in a wet state.

The carrier according to the present invention has a side or diameter of 3
Approximately 15 mm (preferably approximately 5-9 mm), and the material is polyurethane, acrylic, polyethylene, polypropylene, polyvinyl chloride, or other known materials. The shape, granular shape, or any other shape is not particularly limited. And urethane foam of communicating cells, styrofoam of the cells, other plastic granules, sponge granules,
If it is formed of a composite of any one or any combination of a water-permeable cloth, paper, or the like, a large amount of microorganisms will be carried.
In addition, the carrier for supporting microorganisms may have a specific gravity slightly higher than 1 in relation to the specific gravity, or may have a specific gravity of 1 which is the same as water, or may have a specific gravity slightly lower than that of water. And the specific gravity (including the true specific gravity of the carrier itself) is 1
Includes a carrier that can become slightly larger and settle. Lignin in the present invention is a polyelectrolyte that dissociates in water and has a basic structure of phenylpropane, C ₆ -C
_{Since it} is composed of a large hydrophobic skeleton of ₃ and a hydrophilic group such as a hydroxyl group, when a hydrophobic carrier is immersed in this aqueous solution, the surface of the hydrophobic carrier becomes hydrophilic and has wettability. Such a carrier having wettability hardly requires time until it is put into water and settles, and can be settled,
Air bubbles are difficult to adhere due to aeration.

Regarding the affinity with a hydrophobic carrier, it is not that lignin is particularly high as compared with other surfactants, and the lignin's hydrophobic group is chemically (reactive) with the carrier as compared with other surfactants. This is because the carrier is physically strongly bonded, and after the carrier is made wettable, it is released into water and subjected to a processing operation such as aeration or stirring. It is considered that this is because it is unlikely to be dissolved in water during operation. The lignin solution mainly comprises lignin composed of a heavy compound having a high molecular weight hydroxyphenylpropane as a basic unit, and also contains ligninsulfonate, particularly partially desulfonated sodium ligninsulfonate. For example, taking partially desulfonated sodium lignin sulfonate as an example, hydrophobicity is the portion of phenylpropane that excludes the hydroxyl groups of lignin;
Hydrophilicity becomes a hydroxyl group and a sulfonic acid group. The appropriate concentration of the lignin solution is 0.01 to 50 g / l. As an example of a method for supporting this lignin solution on a hydrophobic carrier, a lignin solution (0.01 to 50 g /
It is sufficient that a carrier, for example, a porous carrier such as urethane foam, is forcibly brought into contact with the solution in a vacuum degassed state or carried on the water surface and left standing for several hours to be brought into contact with the carrier. It can have wettability.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a carrier for biological treatment of wastewater of the present invention. Carrier 1 is 6mm
The carrier 1 is made of a hydrophobic member made of porous polyurethane foam having a rectangular parallelepiped shape, and lignin is carried on the wet surface of the carrier 1, and air bubbles are hardly attached to the wet surface to give wettability. It is formed. The carrier 1 that supports lignin on the wet surface and has a wettability that makes it difficult for air bubbles to adhere to the wet surface may be either a dry state or a wet state. The wet state is a state containing water, that is, a state containing water such as a lignin solution or water. As an example of a method for producing the carrier 1, when a high-purity partially-sulfated sodium lignin-sulfonate 0.1 g / l aqueous solution is used as a lignin solution, the hydrophobic member of 6 mm square is put on the water surface and left to stand.
The hydrophobic member initially floating on the water surface is immersed in an aqueous solution in about half a day, and further immersed for several hours to promote contact between the member and lignin, thereby supporting lignin on the wet surface of the member.

Next, as an example of biological treatment of wastewater using the above-described carrier 1 of the present invention, the applicant has filed Japanese Patent Application No. 8-166.
Description will be made using a part of the biological treatment apparatus in the apparatus of each embodiment proposed in Japanese Patent No. 067 and a known biological treatment apparatus. The novel biological treatment apparatus shown in FIG. 2 has a carrier outflow prevention element 12 provided at a lower portion in a reaction tank 10. The carrier outflow prevention element 12 is a mesh mesh of eyes smaller than the carrier 1,
It is formed of either a perforated plate having a smaller hole diameter than the carrier 1, a ceramic filter having a myriad of communicating pores smaller than the carrier 1, or a hard permeable plate member capable of preventing the carrier 1 from flowing out. This reaction tank 10 is provided with an aeration element consisting of an air diffuser slightly above the carrier outflow prevention element 12 in the tank.
13, the aeration element 13 is connected to the blower 14, and the aeration operation is performed by air pressure spouting from the diffuser pipe, and the carrier 1 filled in the tank is rotated in the water by the circulation of the internal liquid 11. It is configured to do so.

In the reaction tank 10, the suction side of a discharge pipe 15 to which a discharge pump 16 is connected is connected to a discharge port 17 at the bottom of the tank below the carrier outflow prevention element 12, and the discharge side of the discharge pipe 15 is connected. Branched, a transfer circulation opening / closing valve 18 is provided on one side and a discharge circulation opening / closing valve 19 is provided on the other side, and the transfer circulation opening / closing valve is provided when the sludge s settled to the lower side of the carrier outflow prevention element 12 is transferred and circulated.
It is configured such that only 18 is opened and only the discharge on-off valve 19 can be opened when the treated water is discharged. Further, the reaction tank 10 is provided with an inlet pipe 21 from a wastewater feed pump 20 and a transfer circulation pipe 22 connected to the transfer circulation opening / closing valve 18, respectively, and a discharge pipe 15, a discharge pump 16, a transfer circulation The transfer circulating element 23 is constituted by the on-off valve 18 for transfer, the transfer circulating pipe 22, etc.
And the introduction of wastewater by the introduction pipe 21 and the transfer and circulation of the settled sludge s around the discharge port to the inner liquid 11 above the water surface by the transfer circulation element 23, and furthermore, the discharge pipe 15 and the discharge pump 1
6. A discharge element 24 for treated water is constituted by the on-off valve 19 for discharge, so that treated water can be discharged.

The waste water introduction operation by the feed pump 20, the aeration operation by the blower 14, the sludge transfer circulation operation by the discharge pump 16 and the transfer circulation on-off valve 18, the sludge sedimentation operation, the discharge pump 16 and the discharge on-off valve 19 The treated water discharge operation by the feed pump 20, blower 14, discharge pump
16, the transfer circulation on-off valve 18 and the discharge on-off valve 19 are controlled by a controller (not shown) so as to operate at appropriate times in a fixed cycle, and are fully automatic operation. In addition, each operation may be operated individually to perform automatic operation, or the transfer circulation on-off valve 18 and the discharge on-off valve 19 of the solenoid valve type may be manually operated as manual valves. Is also good.
HWL shown is the highest water level at the end of wastewater introduction, LW
L is the lowest water level at the end of treated water discharge.

The treatment method using this biological treatment apparatus includes a wastewater introduction step, an aeration step, a sedimentation step, a circulation step, and a treated water discharge step. These steps are operated as one cycle. Waste water introduction step (a in FIG. 4) The feed pump 20 is started, and a predetermined amount of waste water to be treated is introduced into the reaction tank 10 to form the internal liquid 11.

Aeration step (b in FIG. 4) After the feed pump 20 is stopped, the blower 14 is started to supply air from the aeration element 13 into the reaction tank 10 to generate a circulation in the internal liquid 11. Floating activated sludge and carrier 1 for holding microorganisms
Are rotated by the circulating flow. During this rotation process, that is, during the aeration operation, the internal liquid 11 and the microorganisms come into contact with each other to cause an aerobic oxidative decomposition reaction, whereby organic substances are decomposed.

Sedimentation Step (c in FIG. 4) After the blower 14 is stopped and the aeration operation is completed, the process proceeds to the step of sedimentation of the carrier 1 and sludge. Carrier 1 for holding microorganisms
In the process of sedimentation and separation of suspended activated sludge, the carrier 1 is first settled due to a difference in specific gravity, and the activated sludge floc tends to settle with a slight delay. It settles on top of one settled carrier. Part of the settled activated sludge settles on the lower bottom portion of the carrier outflow prevention element 12 to become settled sludge s, and at the same time, the carrier outflow prevention element 12
It is captured in a state sandwiched between.

Circulation Step (d in FIG. 4) After the carrier 1 and the activated sludge have settled, the discharge pump 16 is started, and at the same time, the transfer circulation on-off valve 18 is opened, and the reaction tank 10 is opened.
The treated water is sucked together with the activated sludge s settled around the outlet 17 from the outlet 17 at the bottom of the tank, and transferred to the inner liquid 11 surface in the tank via the transfer circulation pipe 22. The transferred treated water and activated sludge flow down in a settled carrier in a downward flow, but in the course of circulation, SS initially contained gradually decreases, and after the circulation starts, a few After about 10 minutes to 10 minutes, treated water containing almost no SS is obtained. The reason why the treated water is obtained in this way is that the physical filtration function is exhibited in one settling carrier layer. In addition, in the above-mentioned circulation process, the residual soluble organic pollutants (organic substances remaining without aerobic oxidative decomposition in the aeration step) contained in the treated water are also retained on the carrier 1 for the biological treatment function of microorganisms. Is decomposed by Therefore,
In this circulation step, a physical filtration function and a biodegradation function are simultaneously exhibited, and a biological filtration process is performed. During this transfer circulation step, the discharge on-off valve 19
Is closed.

Processed water discharge step (FIG. 4E) The carrier 1 and the activated sludge settle and the transfer circulation on-off valve
After the valve 18 is closed, the discharge pump 16 is restarted, and at the same time, the discharge on-off valve 19 is opened, and the treated water is discharged from the tank as discharge water over a predetermined time. Then, even when the internal liquid 11 is discharged as effluent, the internal liquid 11 flows out through the carrier 1 for retaining microorganisms, so that extremely high-quality treated water can be stably obtained. These steps are repeated as one cycle to continuously treat wastewater.

The known biological treatment apparatus shown in FIG. 3 has an aeration element 101 near the bottom in a reaction tank 100 and a suction port whose suction port is slightly lower than the liquid level of the internal liquid 102. The float 103 is provided in communication with the discharge pipe 104, and is formed so that treated water as supernatant water can be discharged out of the tank by the operation of the discharge pump 105 after the aeration operation. The above-described wastewater introduction operation, aeration operation, sludge sedimentation operation, and treated water discharge operation are controlled by a controller (not shown) such that the wastewater feed pump, blower 106, and discharge pump 105 operate at appropriate times in a fixed cycle. It is controlled by fully automatic operation. Moreover, you may make it operate each operation individually and to drive automatically. HWL shown in the figure is the highest water level at the end of wastewater introduction, and LWL is the lowest water level at the end of treated water discharge.

The treatment method using this biological treatment apparatus includes a wastewater introduction step, an aeration step, a sedimentation step, and a treated water discharge step, and the operation is performed as one cycle. Wastewater introduction step (a in FIG. 5) A wastewater feed pump (not shown) is started, and a predetermined amount of wastewater to be treated is introduced into the reaction tank 100 to form an internal liquid 102.

Aeration step (FIG. 5B) After the feed pump is stopped, the blower 106 is started, and air is supplied from the aeration element 101 into the reaction tank 100 so that the internal liquid 10 is removed.
A circulating flow is generated in 2 and the floating activated sludge and the carrier 1 for holding microorganisms are rotated by the circulating flow. During this rotation process, ie, during the aeration operation, the internal liquid 102 and the microorganisms come into contact with each other to cause an aerobic oxidative decomposition reaction, whereby organic substances are decomposed.

Sedimentation Step (c in FIG. 5) After the blower 106 is stopped and the aeration operation is completed, the process proceeds to the step of sedimentation of the carrier 1 and sludge. Carrier 1 for holding microorganisms
In the process of sedimentation and separation of the suspended activated sludge, the carrier 1 is first settled due to the difference in specific gravity, and the activated sludge floc tends to settle with a slight delay. , Settle at the top of one settled carrier.

Processed water discharge step (d in FIG. 5) After the carrier 1 and the activated sludge s have settled, the discharge pump 105
Is started, and the treated water, which is the supernatant water, is taken in from the suction port of the suction float 103 and discharged as discharge water. These steps are repeated as one cycle to continuously treat wastewater.

[0024]

A. Effects of the Invention According to the first aspect, air bubbles during the biological treatment are hard to adhere, so that the microorganisms can flow and rotate in the water simultaneously with the start of the biological treatment operation without waiting for the attachment of the microorganisms. The rotatable state can be maintained for a long time. B. According to the second aspect of the present invention, it is possible to immediately settle in the water as soon as it is put into the tank, and to prepare a posture for rotation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a carrier for biological treatment of wastewater of the present invention.

FIG. 2 is a sectional view showing an example of the biological treatment device.

FIG. 3 is a sectional view showing another example of the biological treatment device.

FIGS. 4A to 4E show processing steps by the apparatus of FIG.
FIG.

FIGS. 5A to 5D show processing steps by the apparatus of FIG.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Carrier 10,100 Reaction tank 11,102 Inner liquid 12 Carrier outflow prevention element 13,101 Aeration element 14,106 Blower 15,104 Discharge pipe 16,105 Discharge pump 17, Discharge port 18, Transfer circulation on-off valve 19, Discharge on-off valve 20 Feed pump 21 ... Introduction pipe 22 ... transfer circulation pipe 23 ... transfer circulation element 24 discharge element 103 suction float

Claims (2)

[Claims] 1. A wastewater characterized in that lignin is carried on a wet surface of a carrier made of a hydrophobic member to which microorganisms can adhere, and the wet surface has wettability that makes it difficult for air bubbles to adhere thereto. For biological treatment. 2. The carrier for biological treatment of wastewater according to claim 1, wherein said carrier is in a wet state.