JPH0999294A - Waste water treating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of membrane performance due to the insolubilization of nutrient salts and increase in load at the time of performing membrane separation of a treated liquid with biological treatment and flocculation. SOLUTION: This equipment is provided with a biological treatment tank 1 for biologically treating organic waste water, a separation membrane tank 2 into which the biologically treated liquid is introduced and in which a membrane module 7 is immersed, a means 3 for adding nutrient salts to the biological treatment tank 1 and a means 6 for adding a flocculant to the separation membrane tank 2. Accordingly, since this equipment is divided into two tanks, namely the biological treatment tank 1 and the separation membrane tank 2 for subjecting the biologically treated liquid to flocculation and then, to solid-liquid separation with the membrane module 7, the nutrient salts are prevented from being insolubilized by the flocculant to inhibit wasteful consumption of the flocculant due to the insolubilization of the nutrient salts from occurring. Thus, membranes of the membrane module 7 are prevented from being contaminated with BOD causative substances or intermediate products and by using this equipment, stable and effective treatment of waste water can be performed over a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wastewater treatment apparatus, and more particularly, to organic wastewater lacking nutrient salts, which is biologically treated by adding a nutrient salt such as a phosphorus component and then coagulated to form a coagulated liquid. The present invention relates to a wastewater treatment device suitable for separate treatment.

[0002]

2. Description of the Related Art Conventionally, many examples of applying a membrane separation means as a solid-liquid separation means in biological treatment or coagulation treatment have been proposed, for example, there is an apparatus shown in FIG. In the apparatus shown in FIG. 3, raw water is first introduced into a living organism (activated sludge) treatment tank 31 provided with an aeration means including a blower 32 and an air diffusing pipe 33, and treated for aerobic organisms. The biological treatment liquid is introduced into the membrane separation device 35 by the pump 34, a part of the membrane concentrated water is returned to the biological treatment tank 31 as circulating water, and the rest is discharged out of the system. The permeated water of the membrane separator 35 is
The coagulant is introduced into the coagulation tank 36 to coagulate and insolubilize soluble poorly biodegradable organic matter. The coagulation treatment liquid is introduced into the membrane separation device 38 by the pump 37 and is subjected to solid-liquid separation. A part of the membrane concentrated water of the membrane separator 38 is returned to the coagulation tank 36 as circulating water, and the rest is discharged out of the system. On the other hand, the membrane permeated water is discharged out of the system as treated water.

The wastewater treatment equipment of FIG. 3 has two treatment tanks,
Since two membrane separation devices are required and the equipment is complicated, the biological treatment and membrane separation steps and the coagulation treatment and membrane separation steps are combined into one step to simplify the treatment equipment. The device shown in FIG. 4 has been proposed (Japanese Patent Publication 6).
-83837).

In the apparatus shown in FIG. 4, an immersion type membrane module 40 is installed by immersion above the air diffuser 33 in the biological treatment tank 31.
Further, a flocculant addition means is provided to perform aerobic biological treatment and coagulation treatment in the biological treatment tank 31, and the biological treatment and aggregation treatment liquid is sucked by the suction pump 41 to be filtered by the membrane module 40 for solid-liquid separation. To do.

[0005]

The apparatus shown in FIG. 4 can greatly simplify the equipment of the apparatus as compared with the apparatus shown in FIG. 3, but has the following problems.

[0006] In general, in the biological treatment of organic wastewater, when nutrient salts (phosphorus, nitrogen) in the wastewater are insufficient for biological treatment, when these nutrient salts are added to the wastewater for biological treatment. There are many.

In this case, if the nutrient salt, especially the phosphorus component and the flocculant are added to the same treatment tank, the nutrient salt and the flocculant chemically react with each other before the microorganism absorbs and utilizes the nutrient salt, and It produces an insoluble salt that is difficult to be absorbed and utilized by the. For example, the phosphorus salt and the iron compound of the aggregating agent react quickly and become insoluble according to the following formula. Therefore, there is a problem that nutrient salts are not effectively used.

PO ₄ ³⁻ + Fe ³⁺ → FePO ₄ (insolubilization) Further, in this case, not only the nutrient salt but also the coagulant is wastefully consumed, resulting in the coagulation and insolubilization of the soluble biodegradable organic substance. It will not be used effectively.

Moreover, when the separation membrane for solid-liquid separation is immersed and installed in a biological treatment tank for aerobic biological treatment (oxidation treatment), the differential pressure of the membrane is rapidly increased to obtain the required permeation amount. There are many cases that disappear. It was found that this is because the BOD and the intermediate product remained due to the overload, and the membrane was contaminated by condensing these on the membrane surface or adhering to the membrane surface. In some cases, a microorganism adheres to and grows on the membrane surface to form a biofilm-like substance in the catalytic oxidation on the membrane surface, thereby increasing the differential pressure of the membrane.

The present invention solves the above-mentioned conventional problems, and is a wastewater treatment apparatus for subjecting organic wastewater to biological treatment and coagulation treatment, and a coagulation treatment liquid to a membrane separation treatment, wherein the nutrient salt is insolubilized and the load is increased. It is an object of the present invention to provide a wastewater treatment device capable of performing stable and efficient treatment for a long period of time by preventing deterioration of membrane performance due to the above.

[0011]

The wastewater treatment equipment of the present invention comprises a biological treatment tank for biologically treating organic wastewater, a separation membrane tank into which the effluent of the biological treatment tank is introduced, and the inside of the separation membrane tank. A membrane module dipped and installed in the biological treatment tank, a nutrient salt adding means for adding a nutrient salt to the biological treatment tank, a coagulant adding means for adding a coagulant to the liquid in the separation membrane tank or the effluent, and the membrane It is characterized by comprising a treated water extracting means for taking out permeated water of the module as treated water.

In the wastewater treatment equipment of the present invention, the water tank for biological treatment of organic wastewater and the water tank for solid-liquid separation in the membrane module after coagulation treatment are separated, and therefore phosphorus added to the biological treatment tank is separated. Nutrient salts such as components are effectively used and absorbed by microorganisms without reacting with the flocculant to insolubilize them.
In addition, the coagulant is not wastefully consumed for insolubilizing the nutrient salts, and the coagulant is a coagulant of the soluble biodegradable organic matter,
It is effectively used for insolubilization.

Moreover, since the biological treatment is completely carried out in the biological treatment tank, and the BOD and the intermediate product are hardly left, the effluent of the biological treatment tank is membrane-filtered by the membrane module, so that the membrane contamination is prevented and the stable for a long time. And efficient membrane separation can be performed.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings.

1 and 2 are system diagrams showing a method of an embodiment of the waste water treatment equipment of the present invention.

The wastewater treatment equipment shown in FIG.
And a separation membrane tank 2 are provided, and nutrient salts are added to the biological treatment tank 1 through a pipe 3. Also, the biological treatment tank 1 has an air diffuser 4
Is provided, and aeration is performed by the blower 5.

A coagulant is added to the separation membrane tank 2 through a pipe 6. A membrane module 7 is immersed in the separation membrane tank 2, and the permeated water of the membrane module 7 is extracted through a pipe 9 equipped with a suction pump 8. An air diffuser 10 is provided in the lower part of the membrane module 7, and is configured so that the ascending flow generated by the aeration by the blower 5 causes the liquid in the tank to flow, thereby promoting the coagulation treatment and the membrane separation treatment.

Reference numerals 11 to 15 denote liquid transfer pipes, 16,
17 is a pump.

In the waste water treatment apparatus of this embodiment, the organic waste water (raw water) introduced into the biological treatment tank 1 through the pipe 11 is added with nutrient salts through the pipe 3 and aerated under the aeration from the air diffuser 4. Biologically processed.

The biological treatment liquid is introduced into the separation membrane tank 2 through the pipe 12, and the flocculating agent is added through the pipe 6 with a coagulant such as iron salt or aluminum salt. Then, the coagulation treatment liquid is subjected to membrane filtration by suction by the suction pump 8, and the clear permeated water taken out from the membrane module 7 is discharged from the system through the pipe 9 as treated water.

The sludge in the separation membrane tank 2 is extracted from the pipe 13, a part of the sludge is discharged to the outside of the system through the pipe 15 as surplus sludge, and the rest is returned sludge through the pipe 14 through the biological treatment tank 1.
Will be returned to.

In the waste water treatment apparatus shown in FIG. 2, a water tank for coagulation treatment and a water tank for membrane separation are divided, and a coagulation tank 20 is provided between the biological treatment tank 1 and the separation membrane tank 2 to remove biological matter. The biological treatment liquid flowing out from the treatment tank 1 is once received in the coagulation tank 20 through the pipe 12A, the coagulant is added from the pipe 6 in the coagulation tank 20 to perform the coagulation treatment, and the coagulation treatment liquid is passed through the pipe 12B to the separation membrane tank 2 It is different from the waste water treatment apparatus shown in FIG. 1 in that the membrane module 7 is introduced into the membrane module 7 for membrane filtration. An air diffuser 21 is also provided in the coagulation tank 20 so that the blower 5 performs aeration. Other configurations are
Members similar to those of the waste water treatment apparatus shown in FIG. 1 and having the same functions as those shown in FIG. 1 are designated by the same reference numerals.

According to the waste water treatment apparatus of the present invention as described above, since the nutrient salt is added to the biological treatment tank 1 to which no coagulant is added, the nutrient salt is effectively used and absorbed by the microorganisms without being insolubilized, and is efficient. Biological treatment is possible. On the other hand, the aggregating agent added to the separation membrane tank 2 or the aggregating tank 20 is effectively used for aggregating and insolubilizing soluble biodegradable organic substances. Further, even in the case of overload, the biological treatment can be completely carried out in this biological treatment tank 1, so that BOD and intermediate products do not flow out, and this does not contaminate the separation membrane. Also, there is no problem of biofilm growth on the membrane surface. Therefore, it is possible to prevent deterioration of the membrane performance and perform stable and efficient membrane separation treatment for a long period of time.

[0024]

As described in detail above, according to the wastewater treatment apparatus of the present invention, the organic wastewater lacking nutrient salts is biologically treated by adding the nutrient salt, and then subjected to the coagulation treatment and the membrane separation treatment. In doing so, the problem of the reaction between the nutrient salt and the flocculant is solved, and the added nutrient salt is effectively absorbed and utilized by the microorganisms,
The flocculant can be effectively used for the flocculation treatment. Further, even in the case of overload, the separation membrane surface is hardly contaminated with BOD, intermediate products, and further biofilms, preventing deterioration of membrane performance and performing stable and efficient treatment for a long time. You can do it. As a result, the organic wastewater can be efficiently treated and the high-quality treated water can be stably obtained.

[Brief description of drawings]

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

FIG. 2 is a system diagram showing another embodiment of the wastewater treatment equipment of the present invention.

FIG. 3 is a system diagram showing a conventional device.

FIG. 4 is a system diagram showing a conventional device.

[Explanation of symbols]

 1 Biological treatment tank 2 Separation membrane tank 4,10,21 Air diffuser 5 Blower 7 Membrane module 8 Suction pump 20 Coagulation tank

Claims (1)

[Claims] 1. A biological treatment tank for biologically treating organic wastewater, a separation membrane tank into which the effluent of the biological treatment tank is introduced, a membrane module immersed in the separation membrane tank, and the biological treatment. Nutrient salt adding means for adding nutrient salt to the tank, coagulant adding means for adding a coagulant to the liquid in the separation membrane tank or the effluent, and treated water extraction for taking out permeated water of the membrane module as treated water A wastewater treatment device comprising: