JPH08192188A - Method and device for treating organic waste water - Google Patents

Abstract

PURPOSE: To provide a method and device for treating organic waste water with an easy treating operation and a simple device without using chemicals. CONSTITUTION: A device for treating organic waste water comprises a thin film flow-down type evaporator 3 for concentrating organic waste water 14, a gas-liquid separator 4 for gas-liquid separation of generated steam 18, a condenser 6 for condensing separated steam 20, and a biofilm filter 9 for biologically treating condensed water 23 under aerobic conditions, and the evaporator 3 includes a large number of circular tubes in an evaporating drum and waste water flows down over the inner wall of the circular tube, while the waste water is heated with steam 29 from the outside of the tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of organic wastewater, and more particularly to a wastewater treatment method and apparatus for biological treatment of organic wastewater after treatment with an evaporator.

[0002]

2. Description of the Related Art The properties of leachate from landfills for general waste and industrial waste, sludge currently designated as industrial waste, and wastewater in animal excrement are high concentrations of BOD, COD,
In addition to having SS, it has characteristics such as large fluctuation range of concentration. Conventionally, equipment for removing BOD, COD, and SS was installed in double or triple to meet the regulated value of treated water. ing. An example thereof is as follows.

Removal of BOD: A combination of floating biological treatment (so-called activated sludge equipment) and biological membrane biological treatment equipment such as a rotating disk and catalytic oxidation. ○ COD removal: A combination of ozone oxidation equipment and activated carbon adsorption equipment. ○ Removal of SS ... ・ A combination of dehydration equipment, coagulation sedimentation equipment and filtration equipment. In this way, even if many facilities are installed, it is inevitable that the facility will be operated by the management technology based on the long-term experience of many operation managers against fluctuations in the properties of the inflowing wastewater. In addition, there are problems due to the use of many chemicals in biological treatment and coagulation sedimentation treatment and the accompanying generation of excess sludge. Further, when heavy metals are contained in the wastewater, a new chelate resin facility is required, and management of the chelate resin and treatment of used chelate resin are required.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and a method and an apparatus for treating organic wastewater which does not use chemicals in a simple apparatus and is easy to treat. The challenge is to provide.

[0005]

In order to solve the above-mentioned problems, in the present invention, organic wastewater is concentrated by a thin-film flow-down type evaporator to condense generated vapor containing volatile organic substances, and the condensed water is condensed. This is a method for treating organic wastewater, which is characterized by treating aerobic organisms. Further, in the present invention, a thin film flow-down type evaporator for concentrating an organic wastewater, a gas-liquid separator for separating a generated vapor into a gas-liquid, a condenser for condensing the separated vapor, and an aerobic organism for the condensed water. A treatment device for organic wastewater, comprising a biofilm filtration device for treatment.

In the above, the thin film flow-down type evaporator has a large number of circular tubes inside, and is constructed as an evaporation can in which waste water flows down the inner wall of the circular tubes and is heated by steam from the outside of the tubes. Is good. In addition, the biofilm filtration device has a packed bed filled with sand, anthracite, a plastic material, or activated carbon, which is an adhering medium for aerobic microorganisms, and has an inlet for condensed water above the packed bed. However, it has an air inlet and an outlet for treated water at the bottom, and since the biofilm filtration device has a high water resistance when a certain SS is captured, the packed bed is filled with water and air. For backwashing, it is preferable to have an air inlet for backwashing and a backwashing water inlet in the lower portion, and a drainage outlet for leading the backwash drainage to the thin film flow-down type evaporator in the upper portion. Also, the condenser is
It is preferable that the heat exchanger uses cooling water.

As described above, according to the present invention, the organic wastewater is evaporated and concentrated by the thin-film flow-down type evaporator, and the BOD and COD in the wastewater are collected.
The components, SS, heavy metals and other salts are removed as a concentrated liquid, the steam is cooled, and the condensed water is biologically treated to obtain clear treated water. The evaporation cans of the evaporator are shown in Table 1 below.
By utilizing the characteristic that the boiling point of water is lowered by reducing the pressure from the atmospheric pressure as described above, at high temperature (usually 90
C.) under reduced pressure (at a vacuum degree of less than -700 mmHg,
Since it is usually operated at an absolute pressure of 70 to 150 mm of mercury column), organic matter is volatilized in the vapor and cannot be released to the atmosphere as it is. Therefore, once condensed and condensed, the condensed water is aerobic. The organic matter is removed by treatment with a biological treatment method.

[0008]

[Table 1]

The organic matter concentration in the condensate depends on the original wastewater (B
Since the BOD (200 mg / liter or less) is lower than the OD of several hundred to several thousand mg / liter), it is preferable to use a biofilm filtration device. This is due to the fact that advanced management technology is required to maintain and manage activated sludge in activated sludge equipment that is a floating biological treatment, and when the BOD concentration fluctuates to a value higher than the low value in rotating disks and catalytic oxidation equipment. This is because the lack of oxygen and the clogging of the disk and filler due to excess sludge occur. When using a biofilm filtration device, it is necessary to consider the treatment of the cleaning wastewater.
Usually, the washing wastewater is often subjected to coagulation sedimentation treatment, and the coagulation sedimentation treatment equipment was indispensable equipment. However, in the present invention, the SS of the washing wastewater is 500 to 1000 mg /
Keeping in mind that the volume is about 1 liter, the cleaning waste water is treated as it is in the thin film flow-down type evaporator.

[0010]

FIG. 1 shows a flow diagram of an apparatus used for treating the organic wastewater of the present invention, and the operation of each apparatus of the present invention will be described with reference to this drawing. In FIG. 1, when SS is 1000 mg / liter or less of waste water 14, SS is 1000 mg / liter or more of waste water 15, and when the SS is 1000 mg / liter or more, the gravity type sedimentation tank 16 and the centrifuge 17 are used to remove SS. Is 1000 mg / liter or less, and then the treatment of the present invention is performed.

After the wastewater 14 is once stored in the raw water tank 1,
The raw water pump 2 reaches the thin film flow down type evaporator 3. The waste water 3 is heated by the steam 29 outside the tube while the circular tube in the thin film flow-down type evaporator 3 flows down along the inner wall of the tube to evaporate the moisture, and the generated steam 18 enters the gas-liquid separator 4. . In the gas-liquid separator 4, the flowing steam 18
The concentrated liquid 21 brought together with is separated. Evaporation can 3
The concentrated liquid 19 remaining in the lower portion and the concentrated liquid 21 separated by the gas-liquid separator 4 are discharged 22 by the concentrated liquid transfer pump 5. The steam 20 discharged from the gas-liquid separator 4 is cooled by the condenser 6 to the cooling water 30.
The heat is exchanged with the condensate 23. A vacuum pump 7 is installed in the condenser 6, sucks between the evaporator 3 and the condenser 6,
The degree of vacuum is raised.

The structure of the condenser 6 may be a tuber type or a plate type as long as it can indirectly exchange heat with the cooling water 30. The condensed liquid 23 reaches the biofilm filtration device 9 by the condensed water transfer pump 8. The condensate 23 flows downward from the upper part of the biofilm filtration device 9. In the biofilm filtration device 9, sand,
There is a packed bed filled with packing material such as anthracite, activated carbon, plastic material, etc. While the condensate flows, it is kept aerobic by the air sent by the aeration blower 10 and condensed by the microorganisms propagated in the packed bed. Organic matter in the liquid is biodegraded, and the treated water 25 reaches the treated water tank 13.

When the treatment of the organic matter in the concentrated liquid is continued,
The surplus SS generated by the biodegradation of organic matter increases the water flow resistance of the biofilm filtration device 9, so that the inside of the packed bed is washed when a certain water flow resistance is reached. The washing is performed by air washing with an air washing blower 11 for washing the packed bed with air and washing with the treated water 27 in the treated water tank 13 with the washing pump 12 in an upward flow from the lower portion of the packed bed. Excess surplus SS is discharged to the top of the device. The cleaning discharge 28 is returned to the raw water tank 1 and is processed again in the thin film flow down type evaporator.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 A wastewater treatment experiment was conducted according to the flow diagram of FIG. The specifications of the main equipment used are as follows. Thin film flow down type evaporator: φ30 × H1000mm made of cylinder,
(Evaporation tube is made of Pyrex glass) Absolute pressure in can: 100 mm mercury column (boiling point: 51 ° C), water flow condition: 0.8 liter / h,

Biofilm filtration device: φ35 × H1000 mm
Cylindrical vertical tank (made of acrylic), filling material: anthracite (filling height: 500 mm), water flow condition: BOD volume load, 2.5 kg-BOD / m ³
Table 2 shows the filling material / day, the water quality of the raw water used, and the treatment results. In addition,
For comparison, the conventional process flow (coagulation sedimentation-activated sludge-
The quality of treated water by coagulation-precipitation-filtration-treatment with activated carbon) is also shown.

[0016]

[Table 2] As shown in Table 2, in the present invention, a very clean treated water quality can be obtained. In particular, TDS (salt concentration) has a very low value as compared with the conventional method.

Next, when the running costs of the treatment according to the present invention and the treatment according to the conventional method are compared, when the waste water SS is 1000 mg / liter or less, the following Table 3 is shown.
become that way.

[0018]

[Table 3]

[0019]

EFFECTS OF THE INVENTION The present invention provides stable treated water quality with less equipment than the conventional method. During the experimental period, in the conventional method, it was necessary to constantly adjust the chemical injection amount in the coagulation sedimentation treatment, the dissolved oxygen concentration, the microorganism concentration, and the nutrient injection amount in the activated sludge treatment. On the other hand, in the present invention, the treatment can be carried out without being affected by the concentration of organic and inorganic substances in the raw water. This is because the adjustment items of the apparatus in the evaporation method are based on physical indicators of water amount, pressure and temperature. Further, in the present invention,
It is particularly advantageous when the treated water after treating the wastewater is recovered and reused, as compared with the conventional method. This is because, in the present invention, since the condensed water of the vapor contains almost no salts or suspensions by using the evaporation device, a desalination device for collecting and reusing the water is unnecessary. This is because.

[Brief description of drawings]

FIG. 1 is a flow configuration diagram of an apparatus used for treating organic wastewater of the present invention.

[Explanation of symbols]

1: Raw water tank, 2: Raw water pump, 3: Thin film flow down type evaporator,
4: Gas-liquid separator, 5: Concentrated liquid transfer pump, 6: Condenser,
7: Vacuum pump, 8: Condensate transfer pump, 9: Biofilm filtration device, 10: Aeration blower, 11: Air washing blower, 1
2: Washing pump, 13: Treated water tank, 14, 15: Waste water,
16: gravity settling tank, 17: centrifuge,

Claims (6)

[Claims] 1. A method for treating organic wastewater, which comprises concentrating organic wastewater with a thin-film flow-down type evaporator to condense generated steam containing volatile organic substances and subjecting the condensed water to aerobic biological treatment. . 2. A thin-film flow-down type evaporator for concentrating an organic wastewater, a gas-liquid separator for separating a generated vapor into a gas-liquid, a condenser for condensing the separated vapor, and an aerobic biological treatment for the condensed water. An apparatus for treating organic wastewater, comprising: 3. The thin-film flow-down type evaporator has a large number of circular tubes inside, and is configured as an evaporation can in which waste water flows down the inner wall of the circular tubes and is heated by steam from the outside of the tubes. The organic wastewater treatment device according to claim 2, wherein the treatment device is an organic wastewater treatment device. 4. A packing layer filled with sand, anthracite, a plastic material, or activated carbon, which is a medium for adhering aerobic microorganisms, is formed inside the biofilm filtration device, and condensed water is introduced into the upper part of the packing layer. 3. The organic wastewater treatment apparatus according to claim 2, which has a port, and has an air inlet and a treated water outlet at the bottom. 5. The biofilm filtration device has an air inlet for backwashing and a backwash water inlet at the bottom, and a drainage port at the top for guiding the backwash drainage to the thin film flow-down type evaporator. The organic wastewater treatment apparatus according to claim 4, characterized in that: 6. The organic waste water treatment apparatus according to claim 2, wherein the condenser is a heat exchanger using cooling water.