JP2009233572A - Ozone supply method and ozone supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more uniformly supply ozone into a tank by increasing a supply gas total flow, without changing an ozone supply amount or using equipment such as a blower or a compressor separately. <P>SOLUTION: A high concentration oxygen gas from an oxygen concentrator 2, for generating the high concentration oxygen gas with air as a raw material, is used as raw material, and ozone generated by an ozone generator 6 is sent to a supply pipe 8. A waste gas of a high nitrogen gas concentration generated when generating the high concentration oxygen gas is sent from the oxygen concentrator 2 to the supply pipe 8, and dilutes an ozone-containing gas inside the supply pipe 8. The diluted ozone gas is supplied through the supply pipe 8 into a biological treatment tank 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ozone supply method and an apparatus therefor.

  By supplying a small amount of ozone in organic wastewater biological treatment tanks, organic wastewater flow rate adjustment tanks (storage tanks), surplus sludge storage tanks generated by biological treatment such as wastewater, and pipes for treated water, It is known that it is possible to suppress the generation of malodors in tanks and pipes and to suppress the growth of filamentous fungi that causes deterioration of biological treatment performance.

  In an ozone generator used for such a purpose, a high-concentration oxygen-containing gas having a low nitrogen concentration obtained by separating air into oxygen and nitrogen as a raw material gas generally used to prevent NOx generation due to discharge Is used. When such a raw material gas is used, the generated ozone concentration is on the order of several to several tens%. On the other hand, when supplying organic wastewater to biological treatment tanks, flow rate adjustment tanks, and excess sludge storage tanks, the amount of ozone required to obtain the desired effect is the supply of air for the supply to the biological treatment tank It is much smaller than the amount (absorbing amount) and is generally about 1 / several tens to 1 / several hundreds of the air supply amount for the ablating.

When ozone is supplied for the above-mentioned purpose, there are the following problems when the supply amount of ozone itself is small as described above and high concentration ozone is supplied as it is.
・ For the effect of adding a small amount of ozone, it is important to make the contact between the supplied ozone and sludge thin and uniform. However, when high concentration ozone and wastewater organic components come in contact locally, some ozone is completely organic components. It will be consumed by oxidation or inactivation of useful degrading bacteria (sludge).
-If the amount of air supply (gas volume) is small, uniform supply to the tank becomes difficult.

Conventionally, the following method has been adopted as a solution to such a problem.
(1) In a biological treatment tank that is exposed to air, ozone is uniformly supplied into the tank by joining the ozone supply system to the air exposure system (Patent Document 1).
(2) By supplying ozone without diluting, more ozone is supplied in order to compensate for a reduction in the overall effect due to local excessive consumption of ozone.
(3) By increasing the total supply gas flow rate by diluting several times to 10 times with air (blower air supply or compressed air by a compressor), and taking many supply points in the tank, Supply ozone uniformly inside.

JP 2006-314911 A

However, the conventional techniques described in the above (1) to (3) have the following problems.
With regard to (1), the amount of air to be supplied is very large, several tens of times greater than the amount of gas containing the supply loss, and the mixed ozone-containing air is supplied uniformly into the tank in a short time. When the air volume increases, the bubbles become larger and are released outside the tank in a short time. Therefore, the contact time between ozone and water is very short, the dilution rate is high, and the ozone concentration is very low, so the dissolution efficiency is low. In other words, since the effective utilization rate with respect to the supplied ozone amount is lowered, an apparatus for generating a larger amount of ozone is required as a result, and both the equipment cost and the running cost are increased. In addition, since the waste ozone treatment load increases, there is also a problem that the waste ozone treatment cost increases.
As for (2), since it is necessary to supply more ozone, similarly to (1), an increase in the cost of the ozone generator and the operating cost becomes a problem. In addition, since high-concentration ozone gas is supplied to the biological treatment tank, the amount of ozone dissolved in the wastewater increases in the vicinity of the ozone gas blowout into the tank, and not only filamentous fungi that are bad bacteria, Even bacteria useful for treatment are damaged, and the risk of deterioration in treatment performance increases.
As for (3), there is a problem that the equipment for supplying the dilution gas (blower or compressor) is newly required, the equipment cost is increased, and the electric power of these devices is excessive, so that the operating cost is also increased. . .

  The present invention has been made in view of such points, and by increasing the total flow rate of the supply gas without changing the ozone supply amount and without using equipment such as a blower or a compressor, the present invention is more effective than the inside of the tank or piping. The purpose is to supply ozone uniformly.

  In order to achieve the above object, the present invention is a method for supplying ozone to a tank or piping in which organic wastewater or organic sludge is present, which is generated by a PSA oxygen concentrator using air as a raw material. Ozone is generated using high-concentration oxygen gas as a raw material gas, and exhaust gas having a high nitrogen gas concentration discharged from the PSA oxygen concentrator at the time of the ozone generation is mixed with the ozone as a dilution gas to generate diluted ozone gas. The diluted ozone gas is supplied into the tank or the pipe. Here, the exhaust gas having a high nitrogen gas concentration refers to an exhaust gas having a nitrogen gas concentration higher than the nitrogen gas concentration in the atmosphere.

  When generating ozone, if air containing a large amount of nitrogen is used as a source gas, harmful nitrogen oxides (NOx) are generated and the efficiency of ozone generation is reduced, so the generation of such harmful substances is greatly reduced. As a method, high-concentration oxygen from which nitrogen is removed by a PSA (Pressure Swing Adsorption) type oxygen concentrator (PSA oxygen concentrator) is used as a source gas. And the gas with high nitrogen gas concentration produced | generated as exhaust gas by such conventional oxygen concentration processing is normally exhausted as it is.

For example, in a PSA oxygen concentrator capable of continuously supplying high-concentration oxygen, pressurization and depressurization are repeated to selectively adsorb non-oxygen materials such as zeolite from the raw material air. It is discharged from the adsorption tower by returning to atmospheric pressure and released into the atmosphere. Further, the exhaust gas discharged in this way is a gas having a high nitrogen gas concentration. The present invention uses the exhaust gas having a high nitrogen gas concentration as a dilution gas for the high-concentration ozone gas, thereby eliminating the need for equipment and facilities for the dilution gas, and the energy for supplying the dilution gas is originally PSA oxygen. Since the air pressure supplied by the pump provided in the concentrator can be used as it is, no special energy is required.
And according to the present invention, the exhaust gas is mixed with the ozone as a diluent gas to generate diluted ozone gas, and the diluted ozone gas is supplied to the treatment tank and piping for organic waste water. The total supply gas flow rate can be increased without changing the supply amount of itself, and ozone can be supplied more uniformly to the tank and the pipe.

  As the PSA oxygen concentrator used in the present invention, a pressure temperature swing type oxygen concentrator can be used in addition to the pressure swing type. As the ozone generator, various types such as a discharge type and an ultraviolet irradiation type can be used, but the discharge type is more efficient. The dehumidifying treatment is usually performed at the front stage of the PSA oxygen concentrator (water vapor is adsorbed as it is in the adsorption tower), but is not limited as long as it does not impair the function of the oxygen concentration process. It may be before the air blower or pressurization compressor equipped in the apparatus, or at the time of oxygen concentration, and may not be necessary depending on the moisture content of the raw air.

  The ozone supply device of the present invention is generated by a PSA oxygen concentrator that generates high-concentration oxygen gas using air as a raw material, an ozone generator that generates ozone using the high-concentration oxygen gas as a raw material, and the ozone generator. A supply path that is mixed with ozone and exhaust gas with a high concentration of nitrogen gas generated from the PSA oxygen concentrator and is supplied to the tank or pipe in which organic wastewater or organic sludge exists. ing. In this case, it is more preferable to have a flow rate adjusting device that makes the mixing amount of the exhaust gas having a high nitrogen gas concentration variable. As the flow rate adjusting device, for example, a three-way valve is the simplest, and other mass flow controllers can be used.

  According to the present invention, it is possible to supply ozone more uniformly into the tank and piping by increasing the total supply gas flow rate without changing the ozone supply amount and without using equipment such as a blower or a compressor. It is.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1: has shown the outline | summary of the ozone supply apparatus concerning Embodiment, This Embodiment is comprised as an apparatus which supplies diluted ozone gas with respect to the biological treatment tank 1 by air exposure.

  The oxygen concentrator 2 takes in air, which is a raw material for generating concentrated oxygen, by the pump 3 (compressor) and generates concentrated oxygen by the PSA method. At that time, the exhaust gas having a high nitrogen gas concentration compressed by the pump 3 is discharged outside the apparatus.

  The high concentration oxygen gas generated by the oxygen concentrator 2 is sent to the ozone generator 6 through the pipe 5. The ozone generator 6 generates ozone using high-concentration oxygen gas as a raw material gas. As the ozone generator 6, various types such as a discharge type and an ultraviolet irradiation method can be used. In the present invention, an efficient discharge type generator is suitable. The ozone generated by the ozone generator 6 is sent to the supply pipe 8 through the pipe 7 together with the remaining oxygen gas. The pump 3 described above is a device unique to the oxygen concentrator 2 attached to the oxygen concentrator 2.

  On the other hand, the exhaust gas discharged from the oxygen concentrator 2 is released to the outside through the pipe 11, but all or part of the exhaust gas can be supplied to the supply pipe 8. Such switching is switched by the three-way valve 12 provided at the end of the pipe 11 and the supply pipe 8, and the flow rate of the exhaust gas flowing through the supply pipe 8 is also adjusted by the opening degree of the three-way valve 12.

  The opening degree of the three-way valve 12 as described above can be adjusted based on, for example, the ozone concentration in the gas flowing through the pipe 7, and based on this, the desired dilution and flow rate are calculated and mixed in the supply pipe 8. The opening degree of the three-way valve 12 is controlled from the flow rate of exhaust gas. Of course, when the ozone concentration in the gas flowing through the pipe 7 and the desired dilution are known in advance, the opening degree may be adjusted during the trial operation. Since the amount of gas with a high nitrogen gas concentration discharged from the oxygen concentrator 2 is about 20 times the amount of high concentration oxygen, the ozone gas can be diluted up to about 20 times.

  The biological treatment tank 1 is a treatment tank for activated sludge treatment of organic wastewater by the action of aerobic microorganisms. In order to maintain the aerobic environment, the air taken in by the pump 21 is disposed in the tank. A single air diffuser 22 discharges the water into the tank to discharge the drainage.

  The diluted ozone gas flowing through the supply pipe 8 is supplied into the tank by the second air diffuser 13.

  The present embodiment is configured as described above. When ozone is supplied to the biological treatment tank 1, the ozone generator 6 uses the high-concentration oxygen-containing gas generated by the oxygen concentrator 2 as a source gas. Exhaust gas having a high nitrogen gas concentration discharged from the oxygen concentrator 2 is mixed into the supply pipe 8 as a dilution gas in the ozone-containing gas generated by the above, and diluted ozone gas is generated. Then, the diluted ozone gas is supplied into the tank by the second air diffuser 13. Thus, the total flow rate of the supply gas containing ozone can be increased and supplied into the tank without changing the supply amount of ozone itself and without using a dedicated blower or compressor. Therefore, wasteful ozone consumption in the tank due to the supply of high-concentration ozone can be prevented, and ozone can be supplied more uniformly than before.

Hereinafter, specific effects of using the ozone supply device according to the present embodiment will be described, and the effectiveness of ozone dilution and the effectiveness of using the exhaust gas of the oxygen concentrator as a dilution gas fluid will be described. . FIG. 2 shows a change in BOD (Biochemical Oxygen Demand) of the treated water with respect to the volumetric load with respect to the biological treatment tank 1 of FIG. 1. That is, when the exhaust gas from the oxygen concentrator 2 is not mixed into the supply pipe 8), when ozone is diluted (that is, when the exhaust gas from the oxygen concentrator 2 is mixed into the supply pipe 8 and diluted four times) The results of the investigation are shown. In the graph, the vertical axis represents the BOD value of treated water obtained by treating wastewater with a BOD of about 400 mg / l, and the target water quality is 20 mg / l. The horizontal axis shows the total amount of BOD processed in a treatment tank of 1 m ³ per day, and the higher the value, the greater the amount of treated water.

  The inventors have already confirmed that the treatment performance can be improved, the excess sludge can be reduced, and the sludge settling can be improved by supplying a small amount of ozone to the activated sludge treatment tank in the activated sludge treatment of organic wastewater. Yes. In this case, the amount of ozone-containing gas supplied relative to the amount of air used for exposure varies depending on the quality of the wastewater to be treated and the ozone concentration of the supplied ozone-containing gas, but the ozone generator when using the PSA-type oxygen concentrator 2 The concentration at 6 (several to several tens%) is about 1 / several tens to 1 / several hundreds.

When the result shown in FIG. 2 is seen, in the air exposure treatment without addition of ozone, the volume load exceeds the treatment target level around 0.5 kg BOD / (m ³ · d). On the other hand, in the ozone supply process using the exhaust gas of the oxygen concentrator 2 as a dilution gas, the process can be performed at a target level until it exceeds 0.8 kgBOD / (m ³ · d), compared with the case where no ozone is added. Nearly twice the performance has been improved. On the other hand, it can be seen that the amount of ozone supplied is the same, and that the amount of improvement is clearly smaller in the treatment supplied without dilution than in the diluted ozone supply meter. In this experiment, the ozone concentration before dilution is about 4%, and after dilution is 1%.

  Thus, even in the same ozone supply treatment, it was confirmed that the diluted ozone has a higher ozone addition effect. In addition, in the ozone generator 6 using the high-concentration oxygen-containing gas from the PSA-type oxygen concentrator 2 as a raw material gas, the generated ozone concentration range is usually several% to several tens%, and in this range, dilution treatment was performed. It is estimated from this result that a higher ozone addition effect is obtained.

Thus, when adding the same amount of ozone, the mechanism by which a higher ozone addition effect is obtained by diluting to some extent rather than a high concentration has not been completely clarified, but it is presumed that it is due to one of the following reasons.
(1) When supplying an ozone-containing gas that is not diluted in the supply water tank, since the supply gas flow rate is small, it is difficult to inject aeration in a wide area in the water tank, resulting in a local effect.
(2) In the addition of ozone to the activated sludge treatment of organic wastewater, it is confirmed that if the amount of ozone added is increased from the appropriate value, the bactericidal effect will gradually begin to manifest and the activated sludge activity will decrease. is doing. On the other hand, in the resistance of activated sludge constituent microorganisms to ozone, filamentous fungi that are the bad bacteria that caused trouble in activated sludge treatment and other effective fungi are less resistant to ozone and more inactive. I know. In other words, the addition of ozone at a lower concentration does not damage effective bacteria and suppresses the growth of filamentous fungi, whereas the supply of high-concentration ozone is effective together with the filamentous fungus locally. As a result, damage is also caused to various bacteria, resulting in an increase in the damage of effective bacteria in the entire tank and a decrease in the suppression effect of filamentous fungi due to consumption of ozone.

  In addition, although the said embodiment was mentioned as an example which supplies diluted ozone gas with respect to the biological treatment tank 1 by air exposure, this invention is not restricted to this, The flow volume adjustment tank of a waste water treatment apparatus, an oxygen-free tank, sludge The present invention can also be applied when ozone is supplied to the storage tank and the treated water supply pipe. Furthermore, the present invention can be applied to a water purification system, a middle water treatment system, a water treatment system containing a hardly decomposable substance using ozone, and a deodorization method and apparatus using ozone, as well as ozone in liquid and air. The present invention can also be applied to a sterilization system.

  The present invention supplies a predetermined amount of ozone to a biological treatment tank for organic wastewater, a flow rate adjustment tank (storage tank) for organic wastewater, and an excess sludge storage tank generated by biological treatment such as wastewater. It is useful when processing.

It is explanatory drawing which showed typically the outline | summary of the structure of the ozone supply apparatus concerning embodiment. It is a graph which shows the change of the BOD of the treated water with respect to the volume load at the time of supplying diluted ozone gas with respect to the biological treatment tank with the ozone supply apparatus of FIG. 1 compared with the case where it does not dilute and does not add ozone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Biological treatment tank 2 Oxygen concentrator 3 Pump 4 Pump 5, 7, 11 Piping 6 Ozone generator 8 Supply pipe 12 Three-way valve 13 1st air diffuser 21 Pump 22 2nd air diffuser

Claims (3)

A method of supplying ozone to a tank or piping in which organic wastewater or organic sludge exists,
Ozone is generated using high-concentration oxygen gas generated by a PSA oxygen concentrator using air as a raw material,
Exhaust gas having a high nitrogen gas concentration discharged from the PSA oxygen concentrator during the ozone generation is mixed with the ozone as a dilution gas to generate a diluted ozone gas,
An ozone supply method comprising supplying the diluted ozone gas into the tank or pipe. A device for supplying ozone to a tank or pipe in which organic drainage or organic sludge exists,
A PSA oxygen concentrator that generates high-concentration oxygen gas using air as a raw material;
An ozone generator that generates ozone using the high-concentration oxygen gas as a raw material;
A supply path in which ozone generated by the ozone generator and exhaust gas having a high nitrogen gas concentration generated from the PSA oxygen concentrator are mixed and supplied to the tank or the pipe. An ozone supply device. The ozone supply device according to claim 2, further comprising a flow rate adjusting device that makes the mixing amount of the exhaust gas having a high nitrogen gas concentration variable.

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