JP2005238161A - Water treatment apparatus and water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology which prevents water to be treated having a high pollution degree from flowing out into a river, a lake, or sea in an unsterilized state, and effectively sterilizes the water to be treated. <P>SOLUTION: A water treatment apparatus comprises a storm well 1 for storing the water to be treated, a water level sensor 2 for detecting the possibility of overflow of the water to be treated from the storm well 1, a surface scattering turbidity detector 3 for detecting the turbidity of the water to treated and judging the necessity of sterilization of the water to be treated, a pH adjustment device 4 for adjusting the pH of the water to be treated to 5 or lower, a suction pump 5 for transferring the water to be treated to an ozone treatment tank 6 for ozone sterilization, the ozone treatment tank 6, an ozone generator 7, a waste ozone decomposition tower 8, and a pH readjustment device 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a water treatment apparatus and a water treatment method, and more particularly to untreated sewage discharged from a pumping station during rainfall in a combined sewer system that collects sewage and rainwater such as domestic wastewater in a sewer pipe, disinfects, and discharges. The present invention relates to a water treatment apparatus and a water treatment method that are suitable for solving pollution problems such as rivers, lakes, and seas.

  From Non-Patent Document 1 to be described later, it is conventionally known that, in a conventional sewage disinfection facility, an ozone injection rate at which the number of E. coli is 3000 cells / ml or less is determined, and the amount of ozone is injected into an ozone reaction tank for disinfection. . According to Non-Patent Document 1, the target disinfection effect is achieved with an ozone injection rate of about 5 mg per liter of sewage for sewage with low reducing substances such as organic matter and nitrous acid when determining the injection rate of ozone. If there are many reducing substances, ozone is consumed, so more ozone is needed. The cause of this is the oxidation of organic matter and nitrite nitrogen by the ozone (such as E. coli). Competing with the inactivation reaction, ozone consumption will increase.

  On the other hand, from Patent Document 1 described later, it is conventionally known that the pH of water to be treated is adjusted to 5.5 to 6.5, followed by adsorption treatment and ozone treatment. Further, from Patent Document 2 described later, it is conventionally known that the pH is adjusted to 2 to 4 with sulfuric acid during the ozone treatment of COD contained in the precipitated sludge. Further, from Patent Document 3 described later, it is conventionally known that after waste water is nitrified, pH is adjusted and then ozone treatment is performed.

Conventionally, treated water such as sewage and sewage of various technical technologies is stored in treated water storage devices such as rain wells, and when it reaches a certain amount, it is pumped to the water treatment device and disinfected. The policy of processing and releasing into rivers has been adopted. By the way, due to a temporary sudden increase in the amount of sewage and sewage flowing into the treated water storage device or a large amount of rainwater due to rapid rainfall, the water level of the treated water storage device suddenly rises and the storage device As a result, the water to be treated overflowed and flowed into rivers, lakes, and seas without being disinfected and contaminated them. In the past, the actual situation is that the problem of pollution caused by such overflows and overflowing waters has been added. Although the said nonpatent literature 1 and patent documents 1-patent document 3 disclose disinfection and the processing method about to-be-processed water, they do not mention the contamination problem by said overflow water at all.
Sewerage Facility Planning / Design Guidelines and Explanations Part 2 2001 (page 272, Fig. 4.7.8) JP2003-136080A (Claims 1 and 3) Japanese Examined Patent Publication No. 63-39307 (column 4, lines 8 to 11) JP-A-52-28168 (Claim 1)

  In view of the above problems in the present situation, the problem to be solved in the present invention is to prevent treated water having a high degree of contamination from flowing out into rivers, lakes, seas, etc. without being disinfected, and effectively The object is to provide a technique for disinfecting water to be treated.

  The water treatment device of the present invention is an overflow detection device that detects the presence or absence of overflow of treated water stored in the treated water storage device, overflow water from the treated water storage device, or A turbidity detection device for detecting the turbidity of overflowable water having a possibility of overflow, a pH adjusting device for adjusting pH of the overflow water or the overflowable water, the overflow water adjusted for pH, or A disinfection device for disinfecting the overflowable water is provided.

  The water treatment method of the present invention is a first step of detecting the presence or absence of overflow of treated water stored in the treated water storage device, overflow water or overflow from the treated water storage device. The second step of detecting the turbidity of the overflowable water with the possibility of flow, the turbidity of the overflow water or the overflowable water detected in the second step exceeds the turbidity control limit value A third step of adjusting the pH of the overflow water or the overflowable water to 5 or less, and a fourth step of disinfecting the overflow water or the overflowable water adjusted in the third step. It is characterized by comprising a process.

  By including the overflow detection device or the first step, the present invention can detect in advance the presence or absence of overflow of the treated water from the treated water storage device. Including the turbidity detection device or the second step makes it possible to determine the degree of contamination of the water to be treated and to determine whether or not disinfection is necessary. The pH adjustment necessary for effective disinfection in the disinfection device or the fourth step can be performed by the pH adjustment device or the third step, in particular, the pH can be adjusted to 5 or less. By adjusting the pH of the water to be treated to a predetermined range, particularly 5 or less, the reaction rate between the disinfectant described later and the organic matter in the water to be treated is suppressed, and the disinfectant effectively acts on the disinfection of E. coli. And disinfection is performed efficiently. Accordingly, the amount of the disinfectant necessary for obtaining the same disinfecting effect can be reduced, the capacity of the disinfectant generating device and the storage device is reduced, and the equipment cost and running cost can be reduced.

Embodiment 1 FIG.
FIG. 1 is an explanatory diagram of Embodiment 1 of a water treatment apparatus according to the present invention. The water treatment apparatus includes a rain well 1 as an example of the treated water storage apparatus and an example of the overflow detection apparatus. Water level detection device 2, surface scattering turbidity detection device 3 as an example of the turbidity detection device, pH adjusting device 4, pump water pump 5 as an example of the transfer pump, and ozone treatment as an example of the disinfection device It comprises a tank 6, an ozone generator 7, a waste ozone decomposition tower 8, and a pH readjustment device 9.

  To-be-treated water such as domestic wastewater, rainwater, or other sewage sent through a sewer pipe (not shown) flows into the rainwater well 1. The water level 11 changes constantly and may rise rapidly during rainfall. Therefore, the water level 101 of the water to be treated in the rain well 1 is detected by the water level detector 2, and the degree of contamination of the water to be treated is detected by the surface scattering turbidity detector 3.

  The water level detection device 2 includes a water level sensor 201 installed in the rainwater well 1 and a water level detection device main body 202, and the water level 101 of the treated water in the rainwater well 1 is constantly detected by the water level sensor 201. The detection result is input to the water level detection device main body 202. In the water level detection device main body 202, the magnitude of the input value and the magnitude of the temporal change of the input value are continuously monitored.

  According to previous investigations by the present inventors, the degree of contamination of treated water stored in the rain well 1 in the combined sewer system can be substantially evaluated by turbidity, and It has been found that if the turbidity is less than 50 degrees, the degree of contamination is low, and even if it is discharged without being disinfected, it does not substantially contaminate rivers, lakes, seas and the like. The turbidity detection method and the turbidity detection device are not particularly limited, and may be anything as long as it can measure high-concentration turbidity. In the present invention, the surface scattering turbidity detection device 3 as an example is adopted. Has been. The surface scattering turbidity detection device 3 includes a turbidity detection sensor 301 and a turbidity detection device main body 302 installed on the surface of the water to be treated, and the turbidity of the water to be treated in the rain well 1. In particular, the turbidity in the water level 101 (surface layer) and its vicinity is constantly detected by the turbidity detection sensor 301, and the detection result is input to the turbidity detection device main body 302. In the turbidity detecting device main body 302, the magnitude of the input value and the magnitude of the temporal change of the input value are continuously monitored.

  From the water level detection by the water level detection device 2, the likelihood that the water to be treated overflows from the rain well 1 is large, and from the turbidity detection by the surface scattering turbidity detection device 3, the turbidity of the above-mentioned water to be treated is 50 degrees or more. In this case, the water to be treated in the rain well 1 is transferred to the ozone treatment tank 6 by the pumping water pump 5, and a pH lowering agent is added from the pH adjusting device 4 in the course of the transfer. The water to be treated that has been made acidic by the pH lowering agent is disinfected by bubbling of ozone supplied from the ozone generator 7 in the ozone treatment tank 6, and readjusted by the neutralizer supplied from the pH readjustment device 9 ( Neutralized) and released to the outside. Further, unreacted ozone discharged from the ozone treatment tank 6 is guided to the exhaust ozone decomposition tower 8, decomposed by activated carbon or the like, rendered harmless, and released into the atmosphere.

  The ozone supplied to the ozone treatment tank 6 may be pure ozone or an ozone-containing gas obtained by silent discharge treatment of an oxygen-containing gas such as air or oxygen. Even when any ozone is used as the disinfectant, the water to be treated is made acidic by the pH lowering agent supplied from the pH adjusting device 4. By making it acidic, the reaction rate between ozone and organic matter in the water to be treated is suppressed, and ozone effectively acts on disinfection of Escherichia coli, so that disinfection is efficiently performed. Therefore, it is possible to reduce the amount of ozone necessary to obtain the same disinfection effect, and it is possible to adopt a small capacity as the ozone treatment tank 6, the ozone generator 7, and the exhaust ozone decomposition tower 8, and the equipment cost, There is an effect that the running cost can be reduced.

The acidity is preferably 5 or less, but the effect tends to be saturated even if it is excessively acidified. Therefore, it is preferably about 3 or more from the viewpoint of saving the pH lowering agent. Table 1 below shows the results of investigating the relationship between the pH of treated water and the amount of ozone consumed (mg / litre) for treated water with an E. coli count of 3 × 10 ⁵ / ml. From the table, the effect of setting the pH of the water to be treated to 5 or less is clear. The pH lowering agent may be sulfuric acid, nitric acid, hydrochloric acid, or other acids. When the water to be treated having a turbidity of 50 degrees or more is set to about pH 3 to 5, it can be sufficiently disinfected by injection at an ozone amount of about 50 to 80 mg per liter of the water to be treated. The pH readjustment agent supplied from the pH readjustment device 9 may be a neutralizing agent such as sodium hydroxide or potassium hydroxide.

Embodiment 2. FIG.
FIG. 2 is an explanatory diagram of Embodiment 2 in the water treatment apparatus of the present invention. In FIG. 2, the water treatment apparatus according to the second embodiment is different from the water treatment apparatus according to the first embodiment in that the ozone treatment tank 6 employed in the first embodiment is omitted, and the pumping water pump 5 is used instead. That is also used for ozone treatment, that the ozone supplied from the ozone generator 7 is designed to be injected into the treated water before the pumping water pump 5, The exhaust ozone decomposing tower 8 is connected to the exhaust port of the gas-liquid separator 10, and the configuration is otherwise the same. Accordingly, in FIG. 2, the same devices as those shown in FIG.

  In the pumping water pump 5, the treated water is inevitably agitated for transferring the treated water. In the second embodiment, this agitation phenomenon is used for the agitation of the treated water and ozone to achieve ozone disinfection, so that the ozone treatment tank 6 used in the first embodiment is not necessary, and a small size is achieved. Since the use of the gas-liquid separator 10 is sufficient, the equipment cost can be reduced.

  The present invention has been described in detail with reference to the first and second embodiments. However, the present invention is not limited to these embodiments, and is based on the problems of the present invention and the basics of the means for solving the problems. Various modifications are also included. For example, in Embodiment 1 and Embodiment 2, disinfection with ozone is adopted, but as the disinfection device in the present invention, hypohalous acid such as hypochlorous acid, hypobromous acid, hypoiodous acid or the like. A salt may be used as a disinfectant. Further, ozone and hypohalous acid or a salt thereof may be used in combination. Even when hypohalous acid or a salt thereof is used as a disinfectant, the water to be treated is preferably adjusted to a pH of 5 or less in advance by the above pH adjuster from the viewpoint of effectively disinfecting the water to be treated. .

In recent times, the present invention is under the trend of increasing the amount of treated water such as domestic wastewater flowing into rainwater wells due to the improvement of people's living standards, and thereby increasing the possibility of overflow from rainwater wells. Since it is possible to detect the overflow of the water to be treated in advance, perform the necessary disinfection, and achieve it effectively, it will become extremely important in the future when protection of the natural environment is more important.

It is explanatory drawing of Embodiment 1 in the water treatment apparatus of this invention. It is explanatory drawing of Embodiment 2 in the water treatment apparatus of this invention.

Explanation of symbols

1 rain well, 2 water level detection device, 201 water level sensor, 202 water level detection device body,
3 surface scattering turbidity detection device, 301 turbidity detection sensor, 302 turbidity detection device main body,
4 pH adjusting device, 5 pumping water pump, 6 ozone treatment tank, 7 ozone generator,
8 Waste ozone decomposition tower, 9 pH readjustment device, 10 Gas-liquid separation device.

Claims (5)

  Overflow detection device that detects the presence or absence of overflow of treated water stored in the treated water storage device, overflow from the treated water storage device, or overflow that may overflow Turbidity detection device for detecting turbidity of spillable water, pH adjusting device for adjusting pH of overflow water or spillable water, sterilizing pH-adjusted overflow water or spillable water A water treatment device comprising a disinfecting device.   2. The water according to claim 1, wherein the disinfection device is a transfer pump for transferring the overflow water from the treated water storage device or the overflowable water from the treated water storage device to the outside. Processing equipment.   3. The water treatment apparatus according to claim 1, wherein the disinfecting apparatus uses ozone and / or hypohalous acid or a salt thereof as a disinfectant.   First step of detecting whether or not overflow of treated water stored in the treated water storage device is detected or the possibility of overflow, overflow from the treated water storage device or overflow with potential overflow The second step of detecting the turbidity of the potential water, the overflow water or the above when the turbidity of the overflow water or the overflow potential water detected in the second step exceeds the turbidity control limit value A third step of adjusting the pH of the overflowable water to 5 or less, and a fourth step of disinfecting the overflow water or the overflowable water adjusted in the third step. Water treatment method.   5. The water treatment method according to claim 4, wherein ozone and / or hypohalous acid or a salt thereof is used as a disinfectant in the fourth step.

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