JP2006205142A - Tank for conditioning raw water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new tank for conditioning raw water, to which an effective function of treating raw water aerobically or anaerobically can be added, without being affected by water level changes of the tank for conditioning raw water. <P>SOLUTION: A float is arranged on the water surface of the tank for conditioning raw water. The upper end part of a stretchy planar member of a synthetic fiber-knitted fabric is fixed to the float and the stretchy planar member is suspended in the tank for conditioning raw water. The lower end part of the stretchy planar member is positioned at the bottom of the tank for conditioning raw water, so that the stretchy planar member is extended and contracted by the vertical movement of the float due to water level changes of the tank for conditioning raw water. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a tank structure that greatly improves the function of a raw water adjustment tank that averages flow rate fluctuation and concentration in wastewater treatment facilities such as activated sludge treatment.

Kitchen wastewater, food factory wastewater, and the like are typical examples of wastewater whose flow rate and pollutant concentration vary greatly.
When such wastewater is purified at a water treatment facility such as activated sludge treatment or coagulation sedimentation treatment, the wastewater ( Raw water) It is important to install a raw water adjustment tank that averages the flow rate.

The raw water adjustment tank is installed for the purpose of temporarily storing wastewater having a time-varying flow rate, transferring the wastewater to a subsequent water treatment facility at a predetermined flow rate, and stabilizing the treatment effect of the subsequent water treatment facility. Therefore, the raw water adjustment tank water level inevitably fluctuates. Since the required residence time of the raw water in the raw water adjustment tank needs about 6 to 8 hours with respect to the “time average raw water flow rate” in order to sufficiently average the flow rate fluctuation, the raw water adjustment tank needs a large volume. .

However, the conventional raw water adjustment tank has only the function of averaging the flow rate or the pollution concentration of the raw water, and there has been no concept of actively removing pollutant components such as BOD in the raw water adjustment tank itself. In other words, the conventional raw water adjustment tank is only aerated and stirred to prevent the decay of organic substances in the raw water, the generation of hydrogen sulfide, and the prevention of SS sedimentation.

However, recently, a raw water adjustment tank having a function of removing BOD by aerobic microorganisms has come into practical use. For example, [Non-Patent Document]: Nishihara Sanitary Kogyo Co., Ltd. Internet Homepage Catalog “Kitchen Wastewater Treatment System: Improved Biosorption Method” has an aeration device in the raw water adjustment tank and an activated sludge treatment tank in the latter stage It is described that the activated water sludge is returned to the raw water adjustment tank so that the raw water adjustment tank has a function of removing contaminant components by aerobic microorganisms.
However, in this method, since aeration with an oxygen-containing gas such as air is indispensable, an anaerobic biological treatment function by anaerobic microorganisms such as acid-fermenting bacteria cannot be imparted to the raw water adjustment tank. Even when the tempering treatment is performed, the concentration of microorganisms in the raw water adjustment tank cannot be made so high, so that the function of removing the pollutant components cannot be said to be sufficient.

In addition, in the method of adding a biological treatment function by filling a fixed biological attachment member such as a honeycomb tube or a string-like biological attachment material into the raw water adjustment tank, when the water level of the raw water adjustment tank is low Since most of the biological attachment members are exposed on the water surface, there is a great drawback that the attached microorganisms cannot contact the raw water effectively. Further, when the string-like member is suspended, a large load is applied to the water-containing string-like member exposed on the water surface, so that troubles such as the string-like member being cut easily occur.

An object of the present invention is to provide a new-type raw water adjustment tank that can impart an effective anaerobic or aerobic biological treatment function to the raw water adjustment tank without being affected by fluctuations in the water level of the raw water adjustment tank.

The present invention provides a float on the water surface of the tank, fixes the upper end of a “synthetic fiber knitted surface member having elasticity” to the float, suspends the “knitted surface member” in the tank, and lowers the lower end of the member to the tank. It is a raw water adjustment tub characterized by being arranged so as to expand and contract the `` stretchable synthetic fiber knitted surface '' by moving the float with the vertical change of the tank water level by being positioned at the bottom, This is a raw water adjustment tank in which microorganisms such as anaerobic bacteria and aerobic bacteria are attached to the “knitting surface member”. The “float” of the present invention is a float, and those having high buoyancy in water such as a foamed polystyrene block and an air bag are suitable.

(1) Since the biological adhesion member with high elasticity in the height direction of the raw water adjustment tank is provided so as to be able to expand and contract in the vertical direction of the tank via the float, even if the water level of the raw water adjustment tank fluctuates, Is always underwater and never exposed on the surface. Therefore, the total amount of microorganisms can always come into contact with raw water, so that anaerobic or aerobic biological treatment can be effectively performed in the adjustment tank.
(2) As a result, the biodegradability of the organic matter flowing into the biological treatment facility following the raw water adjustment tank is improved, or the BOD load is reduced. As a result, the treatment effect of the subsequent biological treatment facility is stabilized, the treated water quality is improved, and the amount of excess sludge generated is reduced.
(3) Even if the water level in the raw water adjustment tank fluctuates, the biofouling member is not exposed on the surface of the water, so the load is almost zero and the biofouling member is not cut at all.
(4) When the present invention is applied to an existing raw water adjustment tank, if "the float, the organism adhering member and the weight are integrated" is put into the adjustment tank and loaded without draining the water of the adjustment tank. Since it is good, the installation work is very simple and the construction cost is low.

Although the equipment for filling the raw water adjustment tank with a fixed bioadhesive material such as a honeycomb tube or a string-like bioadhesive material has been known, the raw water adjustment tank is filled with a “stretchable bioadhesive member” vertically. As a result, there was no material that provided an effective biological treatment function to the raw water adjustment tank.

Further, the “surface member made of a synthetic fiber knitted fabric having stretchability” is a fabric made by knitting synthetic fibers into a network structure or the like to give stretchability to the fabric surface.
An example of such a woven fabric is Biofix (trade name), which is a product of NTT Corporation shown in FIG.
The knitted fabric (biofix) in FIG. 2 has a large stretchability in the direction of the arrow in FIG. 2 and can be easily stretched with a small force. The biofix has a thickness of about 10 mm in cross section, and has a three-dimensional network structure, so that the area where microorganisms are attached is enormous and a large amount of microorganisms can be attached and immobilized. Can be particularly recommended.

The microorganism adhesion member of FIG. 2 has a three-dimensional net-like core material 1, and the yarn 2 is arranged along the core material 1. Since microbial sludge adheres mainly to the yarn 2, this yarn is referred to as sludge attached yarn 2. The sludge-attached yarn 2 is formed of a thread having good sludge adhesion, such as acrylic high bulk fiber, and is formed with a finer finer than the monofilament 3 constituting the core material 1, The three-dimensional space formed by the material 1 is configured to occupy a predetermined volume ratio.

Since the contact material having such a configuration is arranged in a state in which the connecting yarns having strong waists are entangled along the arrangement direction of the monofilaments 3 and the sludge-attached yarns 2, the monofilaments 3 and the yarns 2 are formed in an uneven shape. In spite of this, the direction perpendicular to the arrangement direction of each monofilament 3 and yarn 2 is not restricted by such a connecting yarn, so that the contact material expands and contracts fairly freely from a predetermined finished state. can do. The wastewater passes through the three-dimensionally arranged sludge adhering yarn 2, so that the contact probability of BOD to the sludge adhering yarn 2 becomes extremely high, and an excellent purification function is exhibited.

The main structure of one embodiment of the present invention will be described with reference to FIG.
The raw water adjustment tank 9 is provided with an inflow portion 10 for waste water (raw water) and a pump 11 that supplies a predetermined flow rate of raw water from the raw water adjustment tank 9 to the subsequent biological treatment process. When the water level in the adjustment tank 9 reaches the lower limit set water level, the motor of the pump 11 is stopped by a signal from a water level detector (not shown). Thereafter, the water level in the tank rises with the inflow of waste water, and the operation of the pump 11 is resumed when the upper limit set water level is reached.

In the raw water adjustment tank 9, a float 5 is provided on the water surface 4, and an upper end portion of the “synthetic fiber knitted surface member 6 that expands and contracts in the vertical direction” is connected to the float 5. A plurality of microorganism-attached knitted surface members 6 are provided in the raw water adjustment tank 9.
The lower end portion of the stretchable synthetic fiber knitted surface member 6 is connected to the weight member 7. Instead of the weight 7, it may be directly connected to the tank bottom. However, when the present invention is applied to the existing raw water adjustment tank 9, if a weight (concrete lump, iron member, etc.) is used, the float, the microorganism adhesion member, and the weight can be removed from the water surface without draining the water in the tank. Easy to install by inserting.

Anaerobic or aerobic microorganisms are immobilized on the stretchable knitted surface member 6. When the use of the raw water adjusting tank 9 of the present invention is started, the microorganisms are attached and fixed to the knitted surface member 6 in a natural growth manner usually in about one week.
At the bottom of the raw water adjustment tank 9, an air diffuser tube 8 is installed when an aerobic treatment is performed in the raw water adjustment tank 9, and a mechanical stirrer is usually installed when an anaerobic treatment is performed.

Therefore, the case where an anaerobic biological treatment is performed in the raw water adjustment tank 1 will be described.
Waste water 10 (raw water) whose flow rate fluctuates with time flows into the raw water adjustment tank 9. Anaerobic microorganisms such as acid-fermenting bacteria adhere to the knitting surface member (microbe-adhering member) 6 installed in the adjustment tank 9 provided with a lid on the top, and the stirrer 8 at the bottom of the tank When the raw water that is stirred and flowed contacts the microorganism attachment member 6 to which microorganisms are attached at a high concentration, organic substances (protein, carbohydrate, etc.) in the raw water undergo acid fermentation and change into organic acids such as acetic acid and lactic acid. The organic acid thus produced has an effect that it is decomposed very rapidly by aerobic microorganisms in the aerobic biological treatment (eg activated sludge method) in the next step.
In addition, anaerobic processing can also be advanced by using the diffuser tube 8 without using a mechanical stirrer. That is, if the amount of air discharged from the air diffusing tube 8 is reduced and the inside of the tank is stopped to such an extent that it can be gently stirred, an oxygen-absorbing tube 8 can be used for anaerobic treatment because there is no dissolved oxygen in the tank. Yes, a stirrer can be dispensed with.
In this case, an exhaust port is attached to the lid of the tank.

Since the waste water in the raw water adjustment tank 9 is sent to the next processing step (not shown) by a metering pump, the water level of the raw water adjustment tank 9 inevitably fluctuates up and down. Since the float 5 also moves up and down according to the water level fluctuation, the stretchable knitted surface member 6 also stretches.
When the water level rises, the stretchable knitted surface member 6 expands, and when the water level falls, the knitted surface member 6 shrinks. As a result, the microorganisms adhering to the stretchable knitted surface member 6 are always located below the water surface, and the total amount of microorganisms functions effectively to purify the wastewater regardless of the water level in the tank.

The length in the vertical direction of the stretchable biological attachment member 6 installed in the adjustment tank is such that when the adjustment tank water level is at the upper limit position, the biological attachment member 6 is substantially extended, and when the adjustment tank water level is at the lower limit of the water level, It is preferable to install so that the adhering member is hardly stretched (a state where no force is applied).

A case where aerobic biological treatment is performed in the raw water adjustment tank 9 will be described.
BOD assimilating (filamentous fungi, zoom glare, etc.) aerobic microorganisms adhere to the microorganism adhering member 6 installed in the raw water adjustment tank 9 at a high concentration, and are aerated by the air diffuser 8 at the bottom of the tank. When the raw water comes into contact with the microorganism-adhering member 6 having a high concentration, about 40% to 60% of the organic matter (protein, carbohydrate, etc.) in the raw water is decomposed into carbon dioxide and water and removed. It is not always necessary to perform aeration from the air diffusing tube 8, and intermittent aeration may be used. Alternatively, a part of the activated sludge of the biological treatment facility following the raw water adjustment tank 9 may be put into the raw water adjustment tank 9 of the present invention, and aerobic treatment may be performed with both the attached microorganisms and the suspended activated sludge.

As a result, the BOD load on the biological treatment facility (activated sludge treatment, etc.) in the next process of the raw water adjustment tank 9 is greatly reduced, the treated water quality of the biological treatment facility is improved, and the amount of surplus sludge generated is greatly reduced. An effect is obtained.
Even when the raw water BOD concentration suddenly increases, the peak cut of BOD can be performed in the raw water adjustment tank 9, so that the subsequent biological treatment facility can purify the raw water with a margin.

One embodiment of the present invention

Example of stretchable synthetic fiber knitted surface member (stretches in the direction of the arrow in the figure)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core material of elastic fabric 2 Yarn 3 Monofilament 4 Tank water surface 5 Float 6 Elastic microbe adhesion member 7 Weight member 8 Aeration tube or stirrer 9 Raw water adjustment tank 10 Raw water inflow part 11 Transfer pump

Claims (2)

A float is provided on the water surface of the tank, and the upper end of the “stretchable synthetic fiber knitted surface member” is fixed to the float, the “knitted surface member” is suspended in the tank, and the lower end of the member is positioned at the bottom of the tank. Thus, the raw water adjustment tank is arranged so that the “stretchable synthetic fiber knitted surface” is expanded and contracted by moving the float as the tank water level changes vertically. 2. The raw water adjustment tank according to claim 1, wherein microorganisms are adhered to the "stretchable knitted surface member".

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