JP2004188240A - Water treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment apparatus in which the pressure loss of a pipeline system is made small, and which has excellent high performance capable of decomposing toxic substances in a short period of time. <P>SOLUTION: This water treatment apparatus is constituted so that a Venturi tube is arranged on a water flow pipeline 1 through which the liquid to be treated is made to flow. An upstream Venturi tube 2A and a downstream Venturi tube 2B are arranged closely to each other in series. An oxidizing solution injecting port 4 is arranged on the upstream side of a throttle part 3a of the tube 2A. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a water treatment apparatus, in particular, for decomposing substances such as harmful chemical substances and pollutants dissolved in water to make them harmless, for efficiently treating organic substances such as sludge, and for sterilizing pathogenic Escherichia coli and the like. The present invention relates to a water treatment device for treating.
[0002]
[Prior art]
As a conventional water treatment apparatus for decomposing substances such as harmful chemical substances and pollutants dissolved in water to make them harmless, and treating organic substances such as sludge, there is one disclosed in Japanese Patent No. 2574736 (Patent Document 1). is there. This conventional water treatment apparatus is for continuously and efficiently detoxifying a liquid to be treated such as water or waste liquid. Hereinafter, this conventional water treatment apparatus will be described with reference to the drawings.
[0003]
FIG. 3 is a sectional view showing a conventional water treatment apparatus.
[0004]
As shown in FIG. 3, the conventional water treatment apparatus is provided with a liquid inflow portion 21 into which a liquid to be treated such as water or waste liquid flows, and a part of a fluid flow path on the downstream side of the liquid inflow portion 21 is provided. It is squeezed by a Venturi tube 22. The venturi pipe 22 has a narrowed portion 22A, a throat portion 22B, and a widened portion 22C formed from the upstream side.
[0005]
An inlet 23 for oxidizing gas for waste liquid treatment is provided slightly downstream of the throat 22B. For example, ozone is used as the oxidizing gas. Hereinafter, ozone will be described as an example. A pressurized mixing flow device 24 is provided downstream of the expanding portion 22C. The pressurized mixing flow device 24 is formed in a box shape, and has a pressurized mixing flow channel 25 in which horizontal flow channels 25A and vertical flow channels 25B are provided alternately and stepwise. A nozzle hole 26 is provided at the outlet of the Kajo mixing channel 25, and the processed liquid is discharged from the nozzle hole 26 to the outside of the pressurized mixing flow device 24.
[0006]
In this conventional water treatment apparatus, ozone is caused to flow into the flow of the liquid to be treated from an inlet 23 provided slightly downstream of the throat section 22B, and the ozone and the substance to be treated are diffused in an expanding section 22C where the flow is slowed. The ozone that has flowed in while mixing with the liquid is dissolved under pressure in the liquid to be treated, and furthermore, a gas flows through the upper part of the pressurized mixing channel 25, and the liquid to be treated flows through the lower part of the channel. The contact area between ozone and the liquid to be treated is increased.
[0007]
In addition, a nozzle hole 26 is provided at the outlet of the pressurized mixing channel 25 through which the liquid to be treated flows down from above, and an outlet-side throttle portion is formed, thereby increasing the static pressure inside the pressurized mixing channel 25. The reaction and dissolution efficiency can be improved.
[0008]
Further, since the processing liquid outlet is lower than the processing liquid inlet, the mixed flow of ozone and the processing liquid is stagnant in the pressurized mixing channel 25. Therefore, the liquid to be treated having a higher density is easier to flow out than ozone, so that more ozone is accumulated in the pressurized mixing channel 25 than the liquid to be treated. Therefore, even if the ratio of ozone in the mixed flow of ozone and the liquid to be processed flowing into the pressurized mixing channel 25 is small, the ratio of ozone is increased in the pressurized mixing channel 25. As a result, the treatment efficiency of the liquid to be treated with ozone is increased.
[0009]
[Patent Document 1] Japanese Patent No. 2574736 [0010]
[Problems to be solved by the invention]
However, the above-mentioned conventional water treatment apparatus has the following problems.
[0011]
(1) Since ozone is injected from the expanding portion 22C slightly downstream from the throat portion 22B of the venturi tube 22, bubbles in the liquid to be processed grow in the low-pressure throat portion 22B and the pressure increases. The time during which the ozone comes into contact with the liquid to be treated is shorter than the time before it collapses in the portion 22C. In other words, the time required for sufficient diffusion of ozone from the interface between ozone and the liquid to be treated into the liquid to be treated cannot be taken.
[0012]
(2) The cavitation bubbles generated in the low pressure throat portion 22B of the venturi tube 22 and disintegrated in the high pressure expanding portion 22C are composed of a very large number of bubble groups. At the outlet of 22, there are many fine bubbles. However, in the conventional water treatment apparatus, ozone is injected from a portion where cavitation bubbles enter a collapse stage, so that the size of ozone bubbles in the expanding portion 22C is excessively large as compared with the fine bubble size. This means that the area of the gas-liquid interface between the ozone bubbles and the liquid to be treated becomes smaller, which causes a reduction in the efficiency of the oxidation treatment with ozone.
[0013]
(3) Since ozone is injected in the vicinity of the expanding portion 22C, which is a bubble collapse portion, the pressure and temperature in the bubble when the cavitation bubble collapses decrease. Conventional water treatment apparatuses perform oxidation treatment of a liquid to be treated using high temperature and high pressure generated when cavitation bubbles collapse, but the pressure and temperature in the bubbles decrease, and the efficiency of oxidation treatment of the liquid to be treated decreases. .
[0014]
Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional water treatment apparatus, and to provide a water treatment apparatus capable of improving the treatment efficiency.
[0015]
[Means for Solving the Problems]
According to a first aspect of the present invention, in the water treatment apparatus, a venturi pipe having a throttle, a throat, and a divergent part is attached from an upstream side to a flowing water pipe through which the liquid to be treated flows. A plurality of oxidizing solution injection ports are provided on the upstream side of the throttle portion of the Venturi pipe arranged in series and arranged on the most upstream side.
[0016]
According to the present invention, an inlet for the oxidizing solution is provided on the upstream side of the throttle portion of the venturi tube, so that an oxidizing solution such as a hydrogen peroxide solution can be injected from the inlet into the liquid to be treated. As compared with the conventional water treatment apparatus described above, a large number of fine bubble nuclei can be generated in the liquid to be treated, and the nucleus in the liquid to be treated can be generated from the interface between the oxidizing solution and the liquid to be treated. In addition, sufficient time is required for the oxidizing solution to sufficiently diffuse.
[0017]
In addition, by using an oxidizing solution as the oxidizing agent, the mixing efficiency of the oxidizing agent into the liquid to be treated is higher than that of a gaseous oxidizing agent such as ozone, and accordingly, a higher oxidation treatment efficiency is obtained.
[0018]
Further, by arranging a plurality of Venturi tubes in series, the efficiency of decomposing harmful substances is further increased as compared with the case of a single Venturi tube.
[0019]
The invention according to claim 2 is characterized in that another inlet for an oxidizing solution is provided between the adjacent venturi tube.
[0020]
According to the present invention, by providing another inlet for the oxidizing solution between the adjacent Venturi tubes, the oxidation of the liquid to be treated is further promoted, so that the efficiency of decomposing harmful substances is further increased. be able to.
[0021]
The invention according to claim 3 is characterized in that the injection port is an injection port of a hydrogen peroxide solution.
[0022]
According to the present invention, by using a hydrogen peroxide solution as the oxidizing solution, the liquid to be treated can be easily oxidized.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the water treatment apparatus of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a schematic sectional view showing a water treatment apparatus of the present invention.
[0025]
The water treatment apparatus according to the present invention comprises an upstream venturi pipe 2A and a downstream venturi pipe 2B arranged in series in the middle of a flowing water pipe 1 through which water to be treated is sent by a pump (not shown). Have been.
[0026]
The flowing water pipe 1 has straight pipes 1a, 1b and 1c. The upstream and downstream venturi pipes 2A and 2B are respectively composed of a throttle portion 3a, a throat portion 3b, and a widening portion 3c, which are formed in this order from the upstream side.
[0027]
An inlet 4 for a hydrogen peroxide solution as an oxidizing solution is provided in the straight pipe line 1a on the upstream side of the upstream venturi pipe 2A.
[0028]
The narrowed portion 3a connecting the straight pipe line 1a and the throat portion 3b of the upstream venturi tube 2A has a maximum diameter portion equal to the diameter of the straight pipe line 1a and a minimum diameter portion equal to the diameter of the throat portion 3b. The diameter in the middle is reduced so that the cross-sectional shape in the pipe direction becomes a 1/4 arc. That is, the constricted portion 3a intersects the straight pipe line 1a at a right angle and is smoothly connected to the throat portion 3b. The connection between the straight pipe line 1b and the downstream venturi pipe 2B is the same as that of the upstream venturi pipe 2A.
[0029]
If another injection port 5 of hydrogen peroxide water as an oxidizing solution is provided in the straight pipe line 1b between the upstream venturi pipe 2A and the downstream venturi pipe 2B, the effect of oxidizing the liquid to be treated can be improved. Even higher. In this case, the length of the straight pipe portion 1b should be such that the fine air bubbles generated at the outlet 6 of the expanding portion 3c of the upstream venturi tube 2A do not recombine or merge.
[0030]
Although the water treatment apparatus in FIG. 1 has two Venturi tubes 2 arranged in series, three or more Venturi tubes may be arranged in series. Also in this case, an injection port of a hydrogen peroxide solution as an oxidizing solution may be provided in a straight line between the venturi tubes. However, as the number of Venturi pipes increases, the required water supply pump head increases, and the energy required for water supply also increases. Therefore, about two to three pipes are considered practically appropriate.
[0031]
Next, the above-described water treatment method using the water treatment apparatus of the present invention will be described with reference to an example in which two Venturi tubes are connected in series.
[0032]
Cavitation bubble nuclei are generated in the liquid to be processed flowing through the straight pipe 1a from the injection port 4 provided in the straight pipe 1a upstream of the inlet of the throttle portion 3a of the upstream venturi 2A, and OH radicals and the like are generated. Hydrogen peroxide (H ₂ O ₂ ), which can generate ozone or the like having a strong oxidizing power, is injected under pressure.
[0033]
By doing so, the injected hydrogen peroxide solution is uniformly diffused in the pipeline before reaching the throat portion 3a of the upstream venturi 2A where cavitation occurs.
[0034]
The static pressure of the liquid to be treated that has flowed into the upstream venturi pipe 2A sharply decreases as the flow velocity in the throttle portion 3a sharply increases. When the static pressure of this portion falls below the saturated water vapor pressure, a large number of fine cavitation bubble nuclei contained in the liquid to be treated are exposed to the low pressure of the throat portion 3b and grow rapidly.
[0035]
The length (L) of the parallel portion of the throat portion 3b is desirably at least three times the diameter d of the throat portion 3b. Thereby, the contact time between the cavitation bubbles and the harmful chemical substance dissolved in the liquid to be treated can be increased. Furthermore, the grown cavitation bubbles rapidly collapse due to a sudden increase in pressure due to a decrease in the flow velocity in the expanding portion 3c.
[0036]
Among the harmful substances contained in the aqueous solution, volatile substances are taken into the bubbles through the gas-liquid interface between the bubbles and the liquid during the growth process of the cavitation bubbles, and the high temperature, high pressure and OH radicals generated when the cavitation bubbles collapse. Is decomposed by the action of On the other hand, non-volatile substances are considered to be decomposed when exposed to high temperature and high pressure at the gas-liquid interface, because they are not taken into the air bubbles much.
[0037]
In addition, microorganisms such as organic substances and other high molecular weight substances, and microorganisms such as Escherichia coli having cell membranes are destroyed by large turbulence caused by the collapse of cavitation bubbles in the vicinity, impact pressure, high temperatures, and the action of OH radicals with strong oxidizing power. It is considered to be decomposed, resulting in low molecular weight, solubilization, and death.
[0038]
Further, since the upstream venturi pipe 2A and the downstream venturi pipe 2B are arranged in series, the inlet pressure and the outlet pressure of the upstream venturi pipe 2A are higher than those in the case of a single venturi pipe. Therefore, the high temperature and high pressure generated when the cavitation bubbles collapse are higher than in the case of a single venturi tube. This has been proved by theoretical calculations. As a result, the efficiency of decomposing harmful substances increases.
[0039]
The cavitation bubble groups generated, grown and collapsed in the upstream venturi tube 2A are innumerable fine bubble groups at the outlet 6 of the expanding portion 3c of the upstream venturi tube 2A. It flows into the downstream venturi tube 2B and becomes a new bubble nucleus for the downstream venturi tube 2B.
[0040]
Accordingly, the number of cavitation bubble nuclei existing at the inlet of the downstream venturi tube 2B is much larger than the number of cavitation bubble nuclei existing at the inlet of the upstream venturi tube 2A. 2B, it grows at the throat 3b and collapses at the widening 3c, like the upstream venturi 2A.
[0041]
By arranging two Venturi tubes in series in this way, the number of bubble nuclei flowing into the downstream Venturi tube 2B increases dramatically, and the area of the gas-liquid interface between the fluid and the bubbles is reduced by the Venturi tube. The number increases dramatically compared to the case of one. As a result, the treatment efficiency of harmful substances contained in the water is significantly increased as compared with the case where one Venturi tube is used.
[0042]
Further, by providing the hydrogen peroxide solution inlet 5 between the upstream venturi pipe 2A and the downstream venturi pipe 2B, the efficiency of treating harmful substances can be further increased.
[0043]
By using the water treatment apparatus provided with the two Venturi pipes described above and the inlet of the hydrogen peroxide solution provided only on the upstream side of the Venturi pipe on the upstream side, the volatile harmful chemical substance m- Decomposition experiments were performed on chlorophenol. The relationship between the elapsed time from the start of the experiment and the concentration (mg / l) of m-chlorophenol in the water to be treated was compared with the results obtained when the same experiment was performed using a single Venturi tube. Is shown in the graph.
[0044]
In this case, in both cases, the flow rate of the water to be treated flowing in the flowing water pipe is 210 (l / min), and the amount of the hydrogen peroxide water injected from the straight pipe portion 1a of the upstream venturi pipe 2A is Of hydrogen peroxide solution of 1000 ppm.
[0045]
As is clear from FIG. 2, the decomposition of m-chlorophenol proceeds faster when the water treatment apparatus of the present invention is used than when one Venturi tube is used.
[0046]
【The invention's effect】
As described above, according to the present invention, in a water treatment apparatus in which a Venturi pipe is arranged in a flowing water pipe through which a liquid to be treated flows, a plurality of Venturi pipes are arranged in close proximity to each other, By providing an oxidizing solution inlet on the upstream side of the throttle section of the Venturi tube arranged in the pipe, pressure loss in the pipeline system is small, excellent decomposition treatment performance of harmful substances is obtained, and And a useful effect of enabling high decomposition processing.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a water treatment apparatus of the present invention.
FIG. 2 is a graph showing the relationship between elapsed time and the concentration of m-chlorophenol in a liquid to be treated.
FIG. 3 is a sectional view showing a conventional water treatment apparatus.
[Explanation of symbols]
1: running water pipes 1a, 1b, 1c: straight pipe 2A: upstream venturi pipe 2B: downstream venturi pipe 3a: throttle section 3b: throat section 3c: expanding section 4: injection port of hydrogen peroxide water 5: excess Hydrogen oxide water inlet 6: Venturi outlet 21: Liquid inlet 22: Venturi tube 22A: Restrictor 22B: Throat 22C: Spread 23: Oxidizing gas inlet 24: Pressurized mixer 25: Pressurized Mixing channel 25A: horizontal channel 25B: vertical channel 26: nozzle hole

Claims (3)

In a water treatment apparatus in which a venturi pipe in which a narrowed portion, a throat portion, and a widened portion are formed from an upstream side is attached to a flowing water pipe through which a liquid to be treated flows,
A plurality of the venturi tubes are arranged in series in proximity to each other, and an inlet for an oxidizing solution is provided on the upstream side of the throttle portion of the venturi tube arranged at the most upstream side. Water treatment equipment. The water treatment apparatus according to claim 1, wherein an inlet for another oxidizing solution is provided between the adjacent venturi tube. The water treatment apparatus according to claim 1, wherein the inlet is an inlet for a hydrogen peroxide solution.

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