JP7590212B2 - Advanced oxidation treatment equipment - Google Patents

Description

The present invention relates to an accelerated oxidation treatment facility, and in particular to an accelerated oxidation treatment facility that effectively decomposes soluble organic matter contained in raw water or wastewater in water purification facilities that produce tap water or industrial water from raw water such as surface water or groundwater, and in wastewater treatment facilities that treat wastewater.

Tap water and industrial water can be broadly divided into those whose source water is surface water such as rivers and lakes, and those whose source water is groundwater. Surface water is particularly susceptible to the influence of external factors, and water pollution has long been a major problem, with unpleasant odors and tastes caused by algae in lakes (causing substances: 2-methylisoborneol, geosmin) and trace harmful substances in rivers caused by industrial wastewater.

However, soluble organic matter, which is the main cause of water pollution, is difficult to sufficiently remove and decompose using conventional processes such as coagulation sedimentation and sand filtration, so measures are being taken to address this issue by adding advanced treatment processes such as ozone treatment and activated carbon treatment.

Among these advanced treatment processes, an advanced oxidation process has been proposed for decomposing soluble organic matter, including unpleasant odors and tastes (see, for example, Patent Documents 1 and 2).
The advanced oxidation process combines ozone, ultraviolet light, an oxidizing agent, etc. to generate highly oxidizing active oxygen, thereby decomposing substances. However, in order to achieve a high decomposition rate, a long reaction time or the administration of large amounts of ozone or ultraviolet light is required, and therefore the fields in which this process has been put to practical use are limited.

JP 2008-62201 A JP 2013-220395 A

The present invention aims to provide an accelerated oxidation treatment facility that employs the above-mentioned accelerated oxidation process and is capable of efficiently and reliably decomposing soluble organic matter, such as unpleasant odors and tastes, while suppressing increases in treatment costs.

In order to achieve the above object, the accelerated oxidation treatment equipment of the present invention is an accelerated oxidation treatment equipment that adds hypochlorite or hydrogen peroxide to the water to be treated by a chemical addition device and irradiates ultraviolet light by an ultraviolet irradiation device to decompose impurities dissolved in the water to be treated, and is characterized in that the accelerated oxidation treatment equipment is equipped with an ultraviolet irradiation device having multiple ultraviolet lamps installed, a measuring means for measuring the concentration of the substance to be removed in the water to be treated, a storage means for storing the correlation between the concentration of the substance to be removed in the water to be treated and the required amount of ultraviolet light irradiation, and a control means for controlling the lighting of the ultraviolet lamps of the ultraviolet irradiation device so that the amount of ultraviolet light irradiation becomes the required amount based on the concentration of the substance to be removed in the water to be treated measured by the measuring means and the correlation between the concentration of the substance to be removed in the water to be treated and the required amount of ultraviolet light irradiation stored in the storage means.

In this case, the ultraviolet irradiation device can irradiate the treated water that has been subjected to a filtering process with ultraviolet rays.

The device may be provided with a storage means for storing the correlation between the required amount of ultraviolet radiation and the required amount of hypochlorite or hydrogen peroxide to be added, and a control means for controlling the amount of chemical added by the chemical addition device so that the amount of hypochlorite or hydrogen peroxide to be added becomes the required amount, based on the correlation between the required amount of ultraviolet radiation and the required amount of hypochlorite or hydrogen peroxide to be added stored in the storage means.

In addition to the chemical addition device that adds hydrogen peroxide to the water to be treated before it is irradiated with ultraviolet rays by the ultraviolet irradiation device, a chemical addition device for removing residual hydrogen peroxide that adds hypochlorite to the water to be treated after it has been irradiated with ultraviolet rays by the ultraviolet irradiation device can be provided.

In addition, a residual chlorine concentration meter can be installed to measure the residual chlorine concentration in the treated water after the accelerated oxidation treatment, and a control means can be provided to control the amount of hypochlorite added based on the measurement value of the residual chlorine concentration meter.

The accelerated oxidation treatment equipment of the present invention can efficiently and reliably decompose soluble organic matter, such as unpleasant odors and tastes, while preventing increases in treatment costs.

These are the experimental results of the mold odor removal rate under each condition. These are the experimental results of the mold odor removal rate under each condition. This is the experimental result of the change in residual chlorine concentration over time. FIG. 1 is an explanatory diagram showing an embodiment of an advanced oxidation treatment facility according to the present invention. FIG. 1 is an explanatory diagram showing an embodiment of an advanced oxidation treatment facility according to the present invention.

Below, an embodiment of the advanced oxidation treatment equipment of the present invention will be described based on an example of application to a water purification treatment facility.

[Low pressure UV lamp + sodium hypochlorite (NaOCl)]
○Target water: Purification treatment; Substances to be removed: Musty odor substances (unpleasant odor and taste substances), pesticides, 1,4-dioxane, organic fluorine compounds ○UV accelerated oxidation treatment conditions: Radiation dose: 200-1000mJ/ ^cm2
・NaOCl injection rate: 0.2 to 4 mg/L (plus residual chlorine in purified water (approximately 0.5 mg/L))
An example of the results of a treatment experiment for mold odor is shown in Figure 1.
It was confirmed that the higher the UV irradiation dose, the more improved the mold odor removal rate.
Furthermore, it was confirmed that, in the case of no NaOCl injection, the removal rate hardly improves even when the UV irradiation dose is increased, whereas, when NaOCl is injected, the removal rate improves at the same UV irradiation dose.
On the other hand, it was revealed that when the NaOCl injection rate was 1 mg/L or more, there was little effect on improving the removal rate.
From the above results, the optimal conditions for this raw water (removal rate 70%) are:
・Irradiation amount: 500mJ/ ^cm2
・NaOCl injection rate: 1mg/L
It was determined that this was the case.
However, since the optimal conditions are thought to vary depending on the raw water quality and the target substance, they must be confirmed through experiments each time.
In addition, the residual chlorine concentration of the treated water at this time was about 0.5 mg/L. Since this is the residual chlorine concentration after post-chlorination in general water purification treatment, it was confirmed that controlling this concentration for chlorine injection management is an efficient operation method for this system.

Adjustment of the Amount of Ultraviolet Irradiation In this advanced oxidation water treatment facility, as shown in FIG. 4, the ultraviolet irradiation device 2 disposed downstream of the rapid filtration basin P1 uses UV lamps (in this embodiment, low-pressure UV lamps). In order to ensure the necessary amount of irradiation in this ultraviolet irradiation device 2, a number of UV lamps will be installed.
Therefore, taking advantage of this feature, the correlation between the type and concentration of the target material in the raw water and the required irradiation amount is confirmed in advance through experiments and stored in the control means, and the control means controls the lighting of the ultraviolet lamps according to the type and concentration of the target material in the raw water; specifically, the system controls the number of lit UV lamps corresponding to the required irradiation amount.
By inputting the type and concentration of the target material into the control panel, the system automatically controls the number of UV lamps turned on, enabling optimal operation control.
If there is a continuous measuring device for the type and concentration of the target material, the signal can be input to enable fully automatic control operation.
Adjustment of NaOCl injection rate (amount of injection) Depending on the type and concentration of the target substance in the raw water, there is a correlation between the required amount of ultraviolet radiation and the NaOCl injection rate (amount of injection) required at that time.
Therefore, the correlation is confirmed in advance by experiment and stored in the control means, and the system controls the NaOCl injection rate (injection amount) by the control means according to the type and concentration of the target substance in the raw water.

[Low pressure UV lamp + _{H2O2 ]}
○Target water: Purification treatment; Substances to be removed: Musty odor substances (unpleasant odor and taste substances), pesticides, 1,4-dioxane, organic fluorine compounds ○UV accelerated oxidation treatment conditions: Radiation amount: 100-500mJ/ ^cm2
・H ₂ O ₂ injection rate: 0.2 to 2 mg/L
An example of the results of a treatment experiment for mold odor is shown in Figure 2.
It was confirmed that the musty odor removal rate relative to the amount of UV irradiation tends to improve as the H ₂ O ₂ injection rate increases.
On the other hand, even when the H ₂ O ₂ injection rate was increased to 1.5 mg/L or more, the musty odor removal rate was hardly improved at all.
From the above results, the optimal conditions for this raw water (removal rate 70%) are:
・Irradiation amount: 350mJ/ ^cm2
・_H2O2 injection rate: 1.5mg _/ L
It was determined that this was the case.
However, since the optimal conditions are thought to vary depending on the raw water quality and the target substance, they must be confirmed through experiments each time.

Adjustment of the Amount of Ultraviolet Ray Irradiation In this advanced oxidation water treatment facility, as shown in FIG. 5, the ultraviolet irradiator 2 disposed downstream of the rapid filtration basin P1 uses UV lamps (in this embodiment, low-pressure UV lamps). In order to ensure the necessary amount of irradiation in this ultraviolet irradiator 2, a number of UV lamps will be installed.
Therefore, taking advantage of this feature, the correlation between the type and concentration of the target material in the raw water and the required irradiation amount is confirmed in advance through experiments and stored in the control means, and the control means controls the lighting of the ultraviolet lamps according to the type and concentration of the target material in the raw water; specifically, the system controls the number of lit UV lamps corresponding to the required irradiation amount.
By inputting the type and concentration of the target material into the control panel, the system automatically controls the number of UV lamps turned on, enabling optimal operation control.
If there is a continuous measuring device for the type and concentration of the target material, the signal can be input to enable fully automatic control operation.
Adjustment of H ₂ O ₂ Injection Rate (Injection Amount) Depending on the type and concentration of the target substance in the raw water, there is a correlation between the required UV irradiation amount and the required H ₂ O ₂ injection rate (injection amount) at that time.
Therefore, the correlation is confirmed in advance by experiment and stored in the control means, and the system controls the H ₂ O ₂ injection rate (injection amount) by the control means according to the type and concentration of the target substance in the raw water.

[Medium pressure UV lamp + sodium hypochlorite (NaOCl)]
○Target water: Purification treatment; Substances to be removed: Musty odor substances (unpleasant odor and taste substances), pesticides, 1,4-dioxane, organic fluorine compounds ○UV accelerated oxidation treatment conditions: Radiation amount: 100-500mJ/ ^cm2
・NaOCl injection rate: 0.2 to 4 mg/L (plus residual chlorine in purified water (approximately 0.5 mg/L))

Adjustment of the Amount of Ultraviolet Ray Irradiation In this advanced oxidation water treatment facility, as shown in FIG. 4, the ultraviolet irradiator 2 disposed downstream of the rapid filtration basin P1 uses UV lamps (medium pressure UV lamps in this embodiment), and in order to ensure the necessary amount of irradiation in this ultraviolet irradiator 2, a number of UV lamps will be installed.
Therefore, taking advantage of this feature, the correlation between the type and concentration of the target material in the raw water and the required irradiation amount is confirmed in advance through experiments and stored in the control means, and the lighting of the ultraviolet lamps is controlled by the control means according to the type and concentration of the target material in the raw water; specifically, the system controls the number of lit UV lamps and/or the lamp light intensity corresponding to the required irradiation amount.
By inputting the type and concentration of the target material into the control panel, the system automatically controls the number of UV lamps turned on and/or the lamp light intensity, enabling optimal operation control.
If there is a continuous measuring device for the type and concentration of the target material, the signal can be input to enable fully automatic control operation.
Adjustment of NaOCl injection rate (amount of injection) Depending on the type and concentration of the target substance in the raw water, there is a correlation between the required amount of ultraviolet radiation and the required NaOCl injection rate (amount of injection) at that time.
Therefore, the correlation is confirmed in advance by experiment and stored in the control means, and the system controls the NaOCl injection rate (injection amount) by the control means according to the type and concentration of the target substance in the raw water.

[Medium pressure UV lamp + _{H2O2 ]}
○Target water: Purification treatment ・Substances to be removed: Musty odor substances (unpleasant odor and taste substances), pesticides, 1,4-dioxane, organic fluorine compounds ○UV accelerated oxidation treatment conditions ・UV irradiation amount: 20 to 300 mJ/ ^cm2
・H ₂ O ₂ injection rate: 0.2 to 2.0 mg/L

Adjustment of the Amount of Ultraviolet Irradiation In this advanced oxidation water treatment facility, as shown in FIG. 5, the ultraviolet irradiation device 2 disposed downstream of the rapid filtration basin P1 uses UV lamps (medium pressure UV lamps in this embodiment), and in order to ensure the necessary amount of irradiation in this ultraviolet irradiation device 2, a number of UV lamps will be installed.
Therefore, taking advantage of this feature, the correlation between the type and concentration of the target material in the raw water and the required irradiation amount is confirmed in advance through experiments and stored in the control means, and the lighting of the ultraviolet lamps is controlled by the control means according to the type and concentration of the target material in the raw water; specifically, the system controls the number of lit UV lamps and/or the lamp light intensity corresponding to the required irradiation amount.
By inputting the type and concentration of the target material into the control panel, the system automatically controls the number of UV lamps turned on and/or the lamp light intensity, enabling optimal operation control.
If there is a continuous measuring device for the type and concentration of the target material, the signal can be input to enable fully automatic control operation.
Adjustment of H ₂ O ₂ Injection Rate (Injection Amount) Depending on the type and concentration of the target substance in the raw water, there is a correlation between the required UV irradiation amount and the required H ₂ O ₂ injection rate (injection amount) at that time.
Therefore, the correlation is confirmed in advance by experiment and stored in the control means, and the system controls the H ₂ O ₂ injection rate (injection amount) by the control means according to the type and concentration of the target substance in the raw water.

[Configuration common to Examples 1 to 4]
In this advanced oxidation water treatment facility, the higher the UV transmittance of the water being treated, the more effective the ultraviolet treatment, so efficient treatment can be achieved by carrying out UV advanced oxidation treatment after filtration, as shown in Figures 4 and 5. The system can also be used for UV disinfection as a measure against chlorine-resistant pathogenic organisms such as Cryptosporidium.

In addition, the system controls the residual chlorine concentration after UV treatment by feeding back the chlorine injection rate so that the residual chlorine concentration in the treated water after the accelerated oxidation treatment reaches the target residual chlorine concentration (for example, 0.2 to 1.0 mg/L). In addition, by making the system also perform post-chlorination, which is generally performed in water purification treatment, the complexity of chlorine injection control, which was mentioned in the conventional technology, can be eliminated.
Furthermore, it was confirmed by experiment that the decrease in residual chlorine concentration up to 4 hours after injection of chlorine (sodium hypochlorite (NaOCl)) was relatively large after UV accelerated oxidation treatment, compared to normal treatment.
Therefore, a residual chlorine concentration meter 5 is installed in the purified water reservoir P2, and chlorine injection control is performed by taking into account the decrease in residual chlorine concentration after the retention time has elapsed.

By the way, it has become clear that when advanced oxidation treatment is performed, organic substances are broken down into smaller molecules compared to normal treated water, and as a result, the amount and manner of chlorine consumption are characteristic.
In the experiment in Example 2, the chlorine demand of the treated water was 3.3 mg/L.
Therefore, the sodium hypochlorite (NaOCl) injection rate was set to chlorine demand + 0.5 mg/L (3.8 mg/L), + 1.0 mg/L (4.3 mg/L), and + 2.0 mg/L (5.3 mg/L), and the changes in residual chlorine concentration over time were compared in Figure 3.
As a result, it was found that when the injection rate was 3.8 mg/L, residual chlorine remained after 1 hour, but disappeared after 4 hours.
A similar tendency was observed in the experimental treated water in Example 1.
This indicates that the official method for measuring chlorine demand (checking chlorine consumption one hour after injecting sodium hypochlorite (NaOCl)) cannot accurately grasp the chlorine demand of advanced oxidation treated water.
From the above results, the set injection rate of NaOCl in the advanced oxidation treatment system including Examples 1 to 4 is set to the chlorine demand of the water to be treated plus 1.0 mg/L or more.
Since the optimal injection rate is thought to vary depending on the raw water quality, adjustments should be made as necessary while checking the residual chlorine concentration after two hours (e.g., four hours) (in particular, the injection rate may need to be set high depending on the concentration of organic matter in the water being treated).
This technology can be applied to the post-processing of all processes using H ₂ O ₂ (O ₃ /H ₂ O ₂ , H ₂ O ₂ single process, etc.) in addition to the first to fourth embodiments.

[Configuration common to Examples 2 and 4]
In this advanced oxidation water purification treatment facility, as shown in FIG. 5, a mechanism for removing residual hydrogen peroxide is provided.
That is, in most cases, H ₂ O ₂ remains in the water to be treated after the treatment using H ₂ O ₂ .
Conventionally, a method of removing this has been adopted in which granular activated carbon filtration is performed to reduce the remaining _H2O2 to water. In this case, a separate granular activated _carbon treatment process is required, which leads to a problem of increased costs. In addition, problems such as the inclusion of activated carbon fine particles or microorganisms propagated in the granular activated carbon treatment tank in the granular activated carbon treatment water have been pointed out in recent years.
On the other hand, the Water Supply Act stipulates that water must be distributed with a certain level of residual chlorine present during water purification treatment.
Therefore, a chemical addition device 6 for removing residual hydrogen peroxide is provided, and a sodium hypochlorite (NaOCl) injection process is added to remove the residual H ₂ O ₂ .
The reaction of NaOCl and H ₂ O ₂ can be represented by the following equation:
NaOCl+ _H2O2 → _NaCl + _H2O + _O2
By utilizing this reaction and adding a certain amount of NaOCl to the H ₂ O ₂ remaining in the treated water, it is possible to remove the residual H ₂ O ₂ in the target water and ensure a certain level of residual chlorine.
By employing this method, it becomes possible to remove the residual H ₂ O ₂ without providing a large-scale treatment process as in the conventional technology.
In addition, by incorporating post-chlorination, which has traditionally been performed in water purification processes, the overall treatment system can be made low cost and space-saving.
This technique can be applied to the post-processing of all processes using H ₂ O ₂ (O ₃ /H ₂ O ₂ , H ₂ O ₂ single process, etc.) in addition to the second and fourth embodiments.

The above describes the advanced oxidation treatment equipment of the present invention based on several examples of water purification equipment, but the present invention is not limited to the configurations described in the above examples, and the configuration can be changed as appropriate within the scope of the spirit of the invention.

The accelerated oxidation treatment equipment of the present invention has the characteristic that it can efficiently and reliably decompose soluble organic matter, such as unpleasant odors and tastes, while suppressing increases in treatment costs when adopting an accelerated oxidation process. Therefore, it can be widely applied to both new and existing water purification treatment equipment, and can also be applied, for example, to wastewater treatment equipment that treats wastewater.

1 Chemical additive device 2 Ultraviolet irradiation device 3 Target substance concentration meter (measuring means)
4 Control section (control means)
5 Residual chlorine concentration meter 6 Residual hydrogen peroxide removal chemical addition device P1 Rapid filtration basin (filtration basin)
P2 Purified water reservoir

Claims (4)

This is an advanced oxidation treatment facility in which hypochlorite is added to filtered water by a chemical addition device and ultraviolet light is irradiated by an ultraviolet irradiation device to decompose impurities dissolved in the water to be treated, the advanced oxidation treatment facility comprising : an ultraviolet irradiation device having a plurality of ultraviolet lamps; a measuring means for measuring the concentration of at least one of substances to be removed in the water to be treated , which are substances having a moldy odor (unpleasant odor and taste), pesticides, 1,4-dioxane, and organic fluorine compounds ; a memory means for storing the correlation between the concentration of the substances to be removed in the water to be treated and the required amount of ultraviolet light irradiation and the required amount of hypochlorite to be added; a control means for controlling the lighting of the ultraviolet lamp of the ultraviolet irradiation device so that the amount of ultraviolet light irradiation is the required amount based on the concentration of the substances to be removed in the water to be treated measured by the measuring means and the correlation between the concentration of the substances to be removed in the water to be treated measured by the measuring means and the required amount of ultraviolet light irradiation and the required amount of hypochlorite to be added stored in the memory means; and a control means for controlling the amount of chemicals added by the chemical addition device so that the amount of hypochlorite added is the required amount . The ultraviolet irradiation device is equipped with a low-pressure UV lamp, sodium hypochlorite is used as the hypochlorite, and the irradiation amount of ultraviolet light to the water to be treated is 200 to 1000 mJ/cm ² 2. The advanced oxidation treatment facility according to claim 1, wherein the injection rate of sodium hypochlorite is set to 0.2 to 4 mg/L. The ultraviolet irradiation device is equipped with a medium pressure UV lamp, sodium hypochlorite is used as the hypochlorite, and the irradiation amount of ultraviolet light to the water to be treated is 100 to 500 mJ/cm ² 2. The advanced oxidation treatment facility according to claim 1, wherein the injection rate of sodium hypochlorite is set to 0.2 to 4 mg/L. The advanced oxidation treatment facility according to claim 1, 2 or 3, further comprising a residual chlorine concentration meter for measuring the residual chlorine concentration in the treated water after the advanced oxidation treatment, and a control means for controlling the amount of hypochlorite added based on the measurement value of the residual chlorine concentration meter .

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