JP4905727B2 - Organic wastewater treatment method and apparatus - Google Patents

Description

  The present invention relates to a biological treatment method and apparatus for organic wastewater, and more specifically, has a function of solubilizing organic sludge using ozone, and the organic wastewater (hereinafter also referred to as “sewage”). The present invention relates to a novel organic wastewater treatment method and apparatus for reducing excess sludge (hereinafter also referred to as “sludge”) generated in a treatment process and improving gas (methane) generation efficiency in anaerobic digestion.

  The activated sludge method is widely used in various fields such as sewage treatment as a method for treating organic wastewater such as sewage. In this purification principle, microorganisms take organic substances in sewage water into cells and perform a purification process using biodegradation. For this reason, microorganisms grow and surplus sludge is generated as a result of the treatment. The final disposal amount of this sludge has a high ratio with respect to the final disposal amount of waste in all industries. In Japan, the residual capacity of the final disposal site is extremely small, which is a great cost burden. Under such circumstances, it is desired to reduce sludge as much as possible, and sludge reduction technology using ozone is spreading. For example, there is an apparatus disclosed in Patent Document 1 as an ozone treatment apparatus that performs efficient solubilization treatment.

In this type of sludge reduction apparatus, sludge solubilization treatment is effectively performed by ozone having strong oxidizing power. In the ozone treatment, ozone gas becomes countless bubbles, and a contact reaction with the treated sludge is performed while ascending the ozone contact tank. When reaching the water level in the tank, the exhaust ozone gas after the contact reaction is separated from the treated sludge. At this time, it rises toward the upper part of the tank as foam with adhering moisture, solubilized sludge, or suspended matter. Since exhausted ozone gas contains harmful ozone, it is necessary to detoxify it with an exhausted ozone decomposing device. However, it is difficult to perform exhausted ozone decomposition in the state of bubbles. It is necessary to do.
JP 2002-336890 A

However, in Patent Document 1, no consideration is given to the structure and mechanism of the defoaming device, and the ability and reliability of defoaming have not been ensured. Further, when the liquid after defoaming is dropped, the liquid adheres to the exhausted ozone gas and the foam is re-formed, so that there is a problem that defoaming cannot be performed efficiently.
An object of the present invention is to provide a wastewater treatment apparatus and a wastewater treatment method provided with a high-efficiency defoaming apparatus that can solve such problems. According to the present invention, a wastewater treatment apparatus and a wastewater treatment method that have a high defoaming ability and reliability and can reduce the maximum amount of foam after refoaming adheres to exhausted ozone gas and foam is regenerated. it can. The waste water treatment apparatus is compact and inexpensive, and can reduce the labor for maintenance and the like to the maximum.

In order to achieve the above object, each invention of the present application has the following configuration.
(1) a contact tank in which organic wastewater is stored;
Ozone gas introduction means for introducing ozone gas into the contact tank ;
Before Symbol motor provided in the upper portion of the contact tank, a rotary blade is rotated on the circumference by the electric motor, and a defoaming wall disposed in the vicinity of the circumference, the rotor blades and the defoaming A defoaming device for extinguishing the bubbles in the contact tank generated by the contact between the ozone gas and the organic waste water due to shear stress caused by a wall ;
In the defoaming device, the electric motor and the rotor blade are connected via a rotating shaft, and a seal portion for shielding the contact tank is formed between the motor and the rotor blade, The seal portion has a laminated structure, and an oil-free first seal made of an ozone-resistant material is installed on the contact tank side, and a lubricating oil made of an abrasion-resistant material is placed on the first seal. It is the waste water treatment equipment in which the 2nd seal | sticker which has is installed .
( 2 ) The defoaming wall is the waste water treatment apparatus according to (1) , wherein the defoaming wall is composed of four walls, and each wall is disposed 90 degrees away from each other in the circumferential direction.
( 3 ) The space above the water surface in the inside of the contact tank is divided into a rising portion where the bubbles rise by introducing the ozone gas, and a dropping portion where the defoaming liquid generated by erasing the bubbles drops. The waste water treatment apparatus according to (1), wherein a partition plate is provided.

According to the present invention, together with that exhaust ozone gas and moisture or the like from leaking to the outside of the contact tank can maximally prevented, it can maximize reduce corrosion by ozone or the like of the motor body.
That is, bubbles generated when ozone gas and organic wastewater come into contact with each other can be effectively eliminated, and efficient wastewater treatment can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the present embodiment, each element is schematically shown for easy understanding of the invention. In this section, the same elements as those described above are denoted by the same reference numerals, and the description thereof may be omitted.

FIG. 1 is a schematic diagram showing the configuration of a sludge reduction apparatus 1 for organic wastewater treatment. In this embodiment, the example which performs the reduction process by ozone of excess sludge using the contact tank 2 of the sludge reduction apparatus 1 shown in FIG. 1 is shown.
The organic waste water 3 is introduced into the contact tank 2 of the sludge reduction apparatus 1 from the introduction port 4, and ozone gas is introduced from the ozone gas supply device 5 through the ejector 6. The ozone gas supply unit 5, the ejector 6, the pump 7, and the circulation line 8 constitute a known circulation system. The introduction port 4 is provided below the contact tank 2.

Inside the contact tank 2, partition plates 5a, 5b, and 5c are provided.
The partition plate 5 a is provided at the center of the contact tank 2, and a gap that enables water flow is provided between the partition plate 5 a and the bottom of the contact tank 2. Further, the upper portion 5a ′ of the partition plate 5a is inclined toward the rising portion 9 side. The tip of the upper part 5a ′ extends to the lower part of the defoaming wall described later. The partition plate 5b is connected to the bottom of the contact tank 2 so that the organic drainage 3 introduced from the introduction port 4 rises in the contact tank 2 to form an upward flow, and its upper part is opened below the water level surface 7. ing. Thereby, after the organic waste water 3 introduced from the introduction port 4 rises, it is guided to the partition plate 5 a and descends to the bottom side of the contact tank 2. In addition, the arrow in the contact tank 2 has shown the direction of the typical water flow typically. The organic drainage 3 lowered by the partition plate 5a rises again by the partition plate 5c and then descends again to the bottom side of the contact tank 2. The lowered organic waste water 3 is discharged from the discharge port 10. By the partition plates 5a, 5b, and 5c, the rising ozone 9 where the foamed liquid becomes foamed by adhering the moisture, solubilized sludge, suspended matter, etc. to the exhausted ozone gas, and the exhausted ozone gas after defoaming It divides | segments into the dripping part 11 into which the isolate | separated antifoaming liquid drip.

  According to the process in which the organic waste water 3 repeats rising and lowering in the contact tank 2 as in this embodiment, the organic waste water can be decomposed more efficiently. Moreover, since ozone gas is supplied from the lower part of the contact tank 2 near the inlet 4, the reaction between the organic waste water 3 and the ozone gas can be effectively performed in the rising water flow. Furthermore, the organic waste water 3 introduced into the contact tank 2 proceeds as a substantially one-way water flow from the introduction port 4 to the discharge port 10, solubilizing treatment with the organic waste water 3 immediately after introduction proceeds. Since the subsequent sludge does not substantially cross, more efficient solubilization can be realized.

  Exhaust ozone gas treated in the contact tank 2 is supplied to an ozone gas decomposing apparatus 12 from an exhaust port, which will be described later, and undergoes decomposing treatment there. The sludge reduction device 1 further includes a defoaming device 100 at the top of the contact tank 2. The defoaming apparatus 100 will be described in detail with reference to FIGS. FIG. 2 is an enlarged cross-sectional view of a main part of the defoaming device 100, and FIG. 3 is a bottom view of the defoaming device 100 as viewed from below.

  The electric motor 101 of the defoaming apparatus 100 is attached to the main body base 103 via the electric motor attachment base 102. These bases and attachment methods can be realized by taking into account known techniques.

  The electric motor 101 includes a rotating shaft 104, and the rotating blade 105 can be rotated by the rotating shaft 104. In the present embodiment, the motor mounting base 102 is installed above the main body base 103, and the motor 101 is installed above the motor mounting base 102. The rotary blade 105 is composed of six flat plate-shaped blades and a circular flat plate 105a for preventing upward scattering on the upper portion thereof. In this embodiment, the rotor blade is formed by six blades, but the rotor blade can be formed by two to eight blades. The rotation speed of the electric motor is set so that the rotation speed of the rotor blades rotates at 500 to 3,000 rpm.

  A seal portion 106 is formed between the rotary blade 105 and the electric motor 101. The seal part 106 installed in the middle part of the rotating shaft 104 is constituted by a double seal. In the present embodiment, a shield bearing 106a (first seal) is provided on the rotor blade 105 side, and a shield bearing 106b (second seal) is provided on the motor side. The first seal 106a is an oil-free seal made of fluororubber having good ozone resistance. For the second seal 106b, a base material made of Teflon (Teflon is a registered trademark) with good wear resistance and lubricity is coated with lubricating oil. According to such a configuration of the seal portion 106, long-term ozone intrusion can be reduced to the maximum, and deterioration of the lubricating oil of the shield bearing on the motor side can be suppressed to the maximum. As a result, the lubricity and durability of the seal portion are improved, and the adverse effect on the motor body can be reduced to the maximum. The material and shape of the shield part can be changed as appropriate according to conditions such as ozone concentration and rotation speed.

    A plurality of defoaming walls 108 are provided in the vicinity of the circumference 107 of the rotor blade 105. In the present embodiment, four defoaming walls 108 are provided and are shifted by 90 degrees from each other. The defoaming wall 108 has a lower width W1 narrower than an upper width W2. That is, the defoaming wall 108 has a tapered shape with a narrowed bottom. Thereby, when the rotary blade 105 is rotated at a high speed, a strong shear stress is generated due to the interaction with the defoaming wall 108 installed on the main body base 103. Thereby, the bubble 109 generated in the rising portion 9 of the contact tank 2 can be effectively removed. Further, since the defoaming wall 108 is formed in a tapered shape, even when hair or fibers contained in the sludge to be treated adhere to the foam and come into contact with the defoaming wall 108, the defoaming wall 108 is entangled. It is possible to suppress problems such as sticking to the maximum. For this reason, there is no decline in the capability of the defoaming function, the maintenance and management are good and the reliability is improved.

  An exhaust port 110 for exhausted ozone gas is provided on the inside of the outer periphery of the attachment of the defoaming wall 108 where the bubble 109 shears. That is, as shown in FIG. 3, an exhaust port 110 for exhausting the exhaust gas in the contact tank 2 is provided above a region defined by two adjacent walls of the defoaming wall.

Here, operation | movement of the sludge reduction apparatus 1 in this embodiment is demonstrated.
Ozone treatment separates the exhaust ozone gas after the contact reaction from the treated sludge. At this time, the exhaust ozone gas becomes a foamed liquid 109 with moisture, solubilized sludge, suspended matter or the like attached thereto, and rises toward the top of the contact tank 2. The rising bubbles come into contact with the rotor blades 105 and scatter to the outer periphery due to the centrifugal force generated by rotating at high speed, and the bubbles 109 are crushed by the strong shearing force generated between the defoaming walls 108. The defoaming liquid that has been crushed and scattered has a defoaming function due to a new synergistic effect of defoaming in contact with the foaming liquid rising from below. With the above operation, the defoaming process is effectively performed.

At this time, most of the defoamed liquid 111 that has been defoamed is dripped into the space of the dripping portion 11. Since the upper part 5a ′ of the partition plate 5a extends to the lower part of the defoaming wall 108 located on the rising part 9 side, the partition plate 5a is hardly dripped onto the rising part 9 aerated by the exhausted ozone gas. Therefore, the liquid after the defoaming hardly adheres to the exhaust ozone gas and the foam is hardly formed. Moreover, since most of the defoaming liquid containing the dripped organic sludge is then refluxed to the ozone treatment circulation line, solubilization is further promoted and an effect of efficient solubilization is obtained. Be able to.
On the other hand, the exhausted ozone gas that has been completely defoamed and separated is sent from the exhausted ozone gas exhaust port 110 to the exhausted ozone decomposing device 12 at the subsequent stage, where the exhausted ozone decomposing process is performed.

  According to the present embodiment, it is possible to realize a processing apparatus having a high-efficiency defoaming apparatus that has high defoaming ability and reliability, and the liquid after defoaming adheres to the exhausted ozone gas and bubbles are not re-formed.

The organic wastewater treatment method and apparatus according to the present invention efficiently solubilizes organic sludge using ozone and re-stratifies it as easily biodegradable, as well as water generated by injecting ozone, solubilized. It is possible to effectively eliminate bubbles adhering sludge or suspended matter.
For this reason, in general organic wastewater treatment using microorganisms for the purpose of removing organic matter such as public sewage, chemical factories, food factories, or industrial wastewater, methane gas is produced through anaerobic digestion process of sludge, and this is used as biomass resources. It is also possible to apply the process to be effectively used as a system and the introduction to facilities for the purpose of reducing the amount of sludge associated therewith.

Schematic which shows the structure of the sludge reduction apparatus which concerns on this embodiment. The principal part expanded sectional view of the defoaming apparatus in this embodiment Bottom view when the defoaming device in this embodiment is viewed from below

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge reduction apparatus 2 Contact tank 100 Defoaming apparatus 101 Electric motor 105 Rotor blade 106 Sealing part 108 Defoaming wall 109 Foam

Claims (3)

A contact tank in which organic wastewater is stored;
Ozone gas introduction means for introducing ozone gas into the contact tank ;
Before Symbol motor provided in the upper portion of the contact tank, a rotary blade is rotated on the circumference by the electric motor, and a defoaming wall disposed in the vicinity of the circumference, the rotor blades and the defoaming A defoaming device for extinguishing the bubbles in the contact tank generated by the contact between the ozone gas and the organic waste water due to shear stress caused by a wall ;
In the defoaming device, the electric motor and the rotor blade are connected via a rotating shaft, and a seal portion for shielding the contact tank is formed between the motor and the rotor blade, The seal portion has a laminated structure, and an oil-free first seal made of an ozone-resistant material is installed on the contact tank side, and a lubricating oil made of an abrasion-resistant material is placed on the first seal. A wastewater treatment apparatus characterized in that a second seal having the following is installed . The waste water treatment apparatus according to claim 1, wherein the defoaming wall is composed of four walls, and each wall is disposed so as to be shifted by 90 degrees in the circumferential direction. The spatial water surface top inside of the contact tank, a rise portion of the foam is increased by introducing the ozone gas, a dropping unit for defoaming liquid caused by erasing the foam drips, partition plate for partitioning the the The wastewater treatment apparatus according to claim 1, wherein the wastewater treatment apparatus is provided.

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