JP3817936B2 - Water quality measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water quality measuring instrument in a rapid filtration pond of a water purification plant in which an improvement is made to cleaning of an optical part of a water quality detector.
[0002]
[Prior art]
The main process at present in water purification plants in Japan is coagulation sedimentation + sand filtration + chlorine disinfection. It is necessary to remove turbidity contained in the raw water and protozoa such as Cryptosporidium, which has been a problem in recent years, by coagulation sedimentation + sand filtration. Among them, the filter basin is an important process that functions as a safety valve for leakage of micro flocs, organic matter adsorption, and protozoa. The filter basin needs to be washed in order to maintain these functions, and this washing is the most important in the operation management of the filter basin. The washing of the filtration basin is generally performed when the filtration duration and the filtration resistance value are reached, and the actual situation is that only physical factors are used as an index. On the other hand, as described above, there is a problem that Cryptosporidium is mixed, and it is necessary to manage the operation of the filtration basin from the viewpoint of water quality. Based on this background, the Ministry of Health and Welfare has issued the following notifications regarding the water quality of the filter basin, the filtration operation of the filter basin, and the washing operation.
[0003]
(1) Common items: For each filtration pond, measure turbidity using a well-adjusted turbidimeter,
(2) Quality of effluent from filtration basin: Maintaining turbidity of filtration basin effluent at all times and maintaining the turbidity at 0.1 degree,
(3) Water quality of washing wastewater: Targeting a final turbidity of 2 degrees or less,
(4) Water quality immediately after the start of filtration: Dispose of the water until the filtration basin effluent reaches 0.1 ° C.
[0004]
In order to maintain the filtration function, it is necessary to wash the filtration pond with an appropriate washing method. There are two types of filtration basin washing methods: surface washing, washing with backwashing water, and a combination of both. The washing method, time, and washing depending on whether the filtration basin is a single-layer filtration using only a sand layer or a combined filtration that combines a sand layer and anthracite. Water flow changes.
[0005]
[Problems to be solved by the invention]
Among the outlines (1) to (4) of the Cryptosporidium Provisional Countermeasure Guidelines by the notification from the Ministry of Health and Welfare mentioned above, in particular, in order to make the final turbidity of the washing drainage turbidity shown in (3) 2 degrees or less, A turbidimeter for the process is required. However, there are few examples of continuous monitoring of the turbidity of washing wastewater in the current rapid filtration pond.
[0006]
This is because it is necessary to clear the following problems.
(1) When medium chlorination is carried out, iron and manganese in the process water react with the chlorinating agent to deposit, adhere to the measuring device, and the electrode and the optical part become dirty.
(2) Due to the structure of the filtration basin, a water quality detector must be installed in the vicinity of the filtration basin in order to measure the washing wastewater. (Throwing type, immersion type)
The detector, particularly the process water quality measuring instrument, is equipped with a cleaning mechanism because air bubbles easily adhere to the optical surface due to adhering suspended substances in the test water or the temperature difference between the water temperature and the measuring instrument. In particular, in an immersion type water quality measuring instrument, the optical part is cleaned by a brush cleaning mechanism, a wiper cleaning mechanism, or the like. However, when the cleaning mechanism is provided, there is a problem that the cleaning effect cannot be expected so much as the entire apparatus becomes large.
[0007]
The present invention has been made in view of the above circumstances, and the detection unit can be downsized as compared with a mechanical cleaning mechanism, and the detection unit is cleaned in a non-contact manner. It is an object of the present invention to provide a water quality measuring instrument that can improve and prevent the adhesion of bubbles and the like to the detection unit.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a water quality measuring instrument that measures the water quality of a filtration pond in a water purification plant with a water quality detector,
A first light source body that is provided in a detection unit main body of a water quality detector that is submerged in water and that irradiates light into the sample water through a transmission window, and the detection that is orthogonal to the irradiation light beam axis from the first light source body A light receiving element provided in the main body for detecting scattered light scattered by particles in water by irradiation of light from the first light source body, a light receiving window provided on the scattered light receiving side of the light receiving element, A photocatalytic reaction material coated on the underwater side of each of the light receiving window and the transmission window, and provided in the detector main body disposed to face the light receiving element, and irradiating the light receiving window and the transmission window. Ri Do and a second light source for emitting a light beam to cause a photocatalytic reaction to the coated photocatalytic reaction substance, first, second light source and the light receiving element is provided integrally with the detector body It is characterized by this.
[0009]
The second invention is characterized in that the first light source body comprises a laser light source or a visible light source.
The third invention is characterized in that the second light source body comprises a light source having a wavelength of 600 nm or less.
The fourth invention is characterized in that the light receiving element is sensitive only to a monochromatic wavelength of 600 nm or more.
The fifth invention is characterized in that the photocatalytic reactant is made of titanium dioxide.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing the configuration of an embodiment of the present invention. In this embodiment, a nephrometry (side scattered light method) turbidimeter using a laser as a light source will be described as an example. In FIG. 1, reference numeral 10 denotes a detection unit body of the turbidimeter, and a semiconductor laser diode (wavelength: 670 nm) 11 is accommodated in the detection unit body 10. The diode 11 emits red laser light, and the laser light 12 passes through a laser transmission window 15 covered with a convex lens 13 and a titanium dioxide coating film 14 and is irradiated into the sample water. Reference numeral 16 denotes a monochromatic light receiving element (an element having spectral sensitivity only for a monochromatic wavelength of 650 nm) made of a silicon photocell. The light receiving element 16 is provided in the detection unit main body 10 orthogonal to the laser beam 12. The light receiving portion of the light receiving element 16 is provided with a light receiving window 18 covered with a titanium dioxide coating film 17.
[0011]
Reference numeral 19 denotes a spectroscopic lamp (for example, a low-pressure mercury lamp or a black light) provided in the detection unit main body 10 disposed so as to face the light receiving element 16. The spectroscopic lamp 19 transmits a light beam 20 having a wavelength of 600 nm or less through a concave lens 21. The transmitting window 15 and the light receiving window 18 covered with the titanium dioxide coating films 14 and 17 are irradiated. Titanium dioxide coated on the transmission window 15 and the light receiving window 18 has a function of causing a photocatalytic reaction by a light beam having a wavelength of 400 nm or less and decomposing an adhering substance by a strong oxidizing power.
[0012]
In the turbidimeter configured as described above, the sample is irradiated with a red laser beam having a wavelength of 670 nm which is finely converged from the semiconductor laser diode 11. Scattered light due to reflection / refraction from turbidity component particles trapped in the light beam irradiated in the sample is detected by the light receiving element 16 arranged in a direction perpendicular to the light beam. The light receiving element 16 sends out an electrical output proportional to the detected scattered light intensity.
[0013]
Since the light receiving element 16 is an element having spectral sensitivity only for a monochromatic wavelength of 650 nm, it cannot absorb light having a short wavelength of 600 nm or less. Therefore, even if light having a wavelength of 600 nm or less emitted from the spectral lamp 19 is irradiated to the light receiving element 16, it is not absorbed, but is scattered light due to reflection / refraction from turbidity component particles trapped in the light beam of the laser light 12. Can be selectively absorbed, and turbidity can be measured without being influenced (background) even when the spectral lamp 19 is continuously lit.
[0014]
On the other hand, when light having a wavelength of 600 nm or less emitted from the spectral lamp 19 is irradiated onto the titanium dioxide coating films 14 and 17 covered with the transmission window 15 and the light receiving window 18, a photocatalytic reaction occurs, and strong oxidizing power is generated. The substance adhering to the coating film is decomposed to clean the windows 15 and 18 from dirt. For this reason, turbidity measurement can always be performed in a good state. In the above embodiment, titanium dioxide is taken as an example of a substance that causes a photocatalytic reaction. However, any substance that causes a photocatalytic reaction at a wavelength of 600 nm may be used. In the above-described embodiment, the case of nepherometry has been described. However, the present invention can be applied to various methods such as transmitted light measurement, forward scattered light measurement, and backscattered light measurement.
[0015]
In the case of using a water quality measuring device using visible light as a light source such as a halogen lamp instead of the water quality measuring device using the semiconductor laser beam, in the measuring system having a transmission window and a light receiving window, the light receiving element 16 Since it will have an effect, the continuous lighting of the spectral lamp 19 cannot be performed. Therefore, when the transmissive window 15 and the light receiving window 18 are cleaned, the measurement circuit (not shown) is limited. For example, the measurement data is not affected by turning on the spectral lamp 19 for a necessary time while holding the output at the hour on the hour at the start of cleaning on the sequence. This function can be applied to various methods such as transmitted light measurement, forward scattered light measurement, and backscattered light measurement.
[0016]
FIG. 2 is a schematic configuration diagram when the turbidimeter is installed in the filter basin. In FIG. 2, 31 is a filter basin, 32 is a washing drain trough, 33 is a light-shielding cover provided on the detector main body 10 described above, 34 is a waterproof tube, 35 is a relay box, and 36 is an operational amplifier device.
[0017]
【The invention's effect】
As described above, according to the present invention, it is not necessary to provide a mechanical cleaning mechanism by forming a coating film of titanium dioxide on the transmission window and the light reception window. In addition, since the window can be cleaned in a non-contact manner, the durability of the detection unit can be improved. In addition, the titanium dioxide film has an advantage that the surface is made hydrophilic by light irradiation from a spectral lamp and adhesion of bubbles and the like can be prevented.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram when a turbidimeter is installed in a filtration pond.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Detection part main body 11 ... Semiconductor laser diode 12 ... Laser beam 13 ... Convex lenses 14, 17 ... Titanium dioxide coating film 15 ... Laser transmission window 16 ... Monochromatic light receiving element 18 ... Light receiving window 19 ... Spectral lamp 20 ... Light with a wavelength of 600 nm or less 21 ... concave lens

Claims (5)

In the water quality measuring instrument that measures the water quality of the filtration pond of the water purification plant with the water quality detector,
A first light source body that is provided in a detection unit main body of a water quality detector that is submerged in water and that irradiates a sample with light rays through a transmission window, and the detection that is orthogonal to the axis of light rays emitted from the first light source body. A light receiving element provided in the main body for detecting scattered light scattered by particles in water by irradiation of light from the first light source body, a light receiving window provided on the scattered light receiving side of the light receiving element, A photocatalytic reaction material coated on the underwater side of each of the light receiving window and the transmission window, and provided in the detection unit main body arranged to face the light receiving element, and irradiating the light reception window and the transmission window. Ri Do and a second light source for emitting a light beam to cause a photocatalytic reaction to the coated photocatalytic reaction substance, first, second light source and the light receiving element is provided integrally with the detector body This is a water quality measuring instrument. The said 1st light source body consists of a laser light source or a visible light source, The water quality measuring device of Claim 1 characterized by the above-mentioned. The said 2nd light source body consists of a light source with a wavelength of 600 nm or less, The water quality measuring device of Claim 1, 2 characterized by the above-mentioned. The water quality measuring instrument according to claim 1, wherein the light receiving element is sensitive only to a monochromatic wavelength of 600 nm or more. The water quality measuring instrument according to claim 1, wherein the photocatalytic reaction material is made of titanium dioxide.

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