JP2702081B2 - Light shield for water treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light shielding plate for a water treatment facility suitably used for a water treatment facility using a biofilm.

[0002]

2. Description of the Related Art Conventionally, in order to remove suspended substances such as turbidity and bacteria in water, and dissolved substances such as ammonia, manganese and odorous substances, and to improve raw water quality, for example, as a pretreatment of a water purification process, Biological treatment has been widely introduced.
The biological treatment method used as this pretreatment is a so-called biofilm treatment method of so-called biofilm treatment, in which organisms attached to the surface of a honeycomb tube or granular filler immersed in water are brought into contact with raw water. However, it is widely used due to its land use and economy. For example, "Survey Report on Standardization of Advanced Treatment Facilities" issued by Japan Water Works Association [Technical Data of Advanced Water Treatment Facilities (Biological Treatment Facilities)] Describes a standardization plan for a honeycomb vertical circulation flow system. Also JP 63
JP-175690 discloses a biofilm treatment method using a particulate filler.

[0003] However, such a method has a problem that, depending on the quality of raw water, green filamentous algae adhere to the surface of the filler, and the biofilm is abnormally enlarged and clogging of the filter medium is often observed. there were. This clogging causes water flow obstruction, which not only reduces the frequency of contact between the raw water and the biofilm, but also reduces the supply of oxygen in poorly distributed areas, causing the biofilm to gradually become anaerobic. This also lowers the processing efficiency. In order to recover the processing efficiency, it is necessary to drain the water in the processing tank or to install a cleaning device in the processing tank for cleaning. Is inefficient and inefficient. Therefore, a method for suppressing the occurrence of green algae and preventing the clogging itself has been required.

[0004] In response to such a problem, for example, in the above-mentioned "Investigation Report on Standardization of Advanced Treatment Facilities," the biological treatment tank is shielded from sunlight to suppress the enlargement of the biofilm. It proposes to clear the clog. However, when the present inventor conducted experiments, it was possible to suppress the occurrence of green algae and completely eliminate clogging if light was completely shielded so that light did not enter the inside of the treatment tank,
It was found that the activity of living organisms was weakened in winter when the water temperature was low, and the ammonia nitrogen removal efficiency was extremely poor, especially when compared with the case without shading. This difference reached a maximum of 20%, greatly impairing the original function of biological treatment. That is, in the conventional biofilm treatment method using the immersion filter bed, there is a problem that the clogging of the filler occurs unless the light is shielded, and the efficiency of removing ammoniacal nitrogen is reduced if the light is shielded.

[0005]

SUMMARY OF THE INVENTION The present invention solves such a problem, and in particular, in a water treatment facility using a biofilm, the generation of green algae can be suppressed without impairing the function of biological treatment. It is an object of the present invention to provide a light-shielding plate for water treatment equipment.

[0006]

In order to solve this problem, the present invention has a minimum wavelength of 450 nm or more and a maximum wavelength of 6 nm.
Has the ability to transmit light in the wavelength range of 00 nm or less , and
The gist is that the light transmittance is 0.005% or more .

Next, the present invention will be described in detail. The light-shielding plate for water treatment equipment of the present invention is required to have a property of transmitting only light in a wavelength region having a minimum wavelength of 450 nm or more and a maximum wavelength of 600 nm or less, and generally has a green color in this wavelength range. Is presented. If the wavelength of the transmission region deviates from this range, it is difficult to suppress the generation of green algae. For example, when used for biofilm treatment, clogging of the filler occurs.

Further, in the light-shielding plate for water treatment equipment of the present invention, the light transmittance is preferably 0.005% or more. When the light transmittance is less than 0.005%, for example, when applied to biofilm treatment, the biological treatment function is not sufficiently exhibited, such as a decrease in the removal efficiency of ammonia nitrogen.

The material forming the light-shielding plate for water treatment equipment of the present invention is not particularly limited. For example, a green dye may be applied to the surface of transparent glass or plastic, or a mixture of a thermoplastic resin and a green pigment may be molded.

Although the reason why the light-shielding plate of the present invention has the effect of suppressing the generation of green algae is not always clear, it blocks light necessary for the activity of green algae and minimizes the light required for the activities of other organisms. It is thought that there is a function to pass through.

The light-shielding plate for water treatment equipment of the present invention can be used in a wide range of water treatment equipment in which green algae are generated, such as pre-treatment of raw water for tap water and higher-order treatment of waste water and sewage. .

[0012]

The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention.

First, as Example 1, a polyester resin was molded by adding a true green pigment, and the visible light transmitting region was 46%.
A light-shielding plate 6 for water treatment equipment having a wavelength of 6 nm to 593 nm and a light transmittance of 0.01% was prepared. This light shielding plate 6 was used in a honeycomb type biofilm water treatment facility for pretreatment of tap water as shown in FIG. In FIG. 1, water to be treated 1 is treated by microorganisms attached to the surface of the honeycomb tube 3 while moving in a honeycomb tube (filler) 3 disposed inside a treatment tank 2. An air diffuser 4 is provided below the processing tank 2 to supply dissolved oxygen by blowing air from the air diffuser 4. In addition, the water is circulated by the pump 5 in order to increase the frequency of contact between the water 1 to be treated and the honeycomb tube 3.

The processing tank 2 is made of a steel plate, so that light can enter only through the opening 2a on the upper part of the processing tank 2.
The opening 2a is covered with the light-shielding plate 6 having green translucency.

[0015] Table 1 shows the design and operating conditions of this water treatment facility.

[0016]

[Table 1]

As Comparative Example 1, the biofilm water treatment equipment used in Example 1 was the same as the biofilm water treatment apparatus except that the upper part of the treatment tank 2 was kept open and sunlight was allowed to enter. Facilities were prepared.

During the summer season when green algae are likely to occur, the same water to be treated (raw water from tap water) was continuously supplied to each of the water treatment facilities in Example 1 and Comparative Example 1 to observe the treatment efficiency and the state of clogging of the honeycomb. However, Comparative Example 1 without shading
1 month after the start of operation, clogging was observed due to enlargement of the biofilm, and the upper end of the honeycomb tube was almost completely closed. On the other hand, in Example 1 covered with the green light-shielding plate 6, the occurrence of green algae was not observed.
There was no blockage of the honeycomb tube 3, and the water flowed smoothly.

As Comparative Example 2, the same equipment as that of Example 1 was used, and the upper part of the processing tank 2 was covered with a light-shielding plate that does not transmit light at all, so that light did not completely enter inside. In December), the same water to be treated (raw water from tap water) was kept flowing, and the change in the removal rate of ammonia nitrogen was examined. The result is shown in FIG. As is clear from FIG. 2, in the case of Comparative Example 2 in which the upper part of the treatment tank was completely shielded from light, the removal rate was very low when the water temperature in winter was low. In the case of Example 1 using the covered equipment, no reduction in the removal rate was observed. During this time, no clogging of the honeycomb tube occurred at all, and there was no particular problem in maintenance.

[0020]

The light-shielding plate of the present invention can be applied to a water treatment facility where green algae are generated, and can suppress the generation of green algae. In particular, when applied to water treatment equipment using biofilms, it prevents clogging between fillers, and at the same time, reduces the decrease in ammonia nitrogen removal efficiency during periods of low biological activity due to low temperatures. The processing function is not impaired, and an extremely large effect can be obtained from both the processing efficiency and the ease of maintenance.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a biofilm water treatment apparatus used in Example 1 of the present invention.

FIG. 2 is a graph showing changes in the removal rate of ammonia nitrogen in Example 1 and Comparative Example 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 To-be-processed water 2 Processing tank 3 Honeycomb tube (filling material) 4 Air diffuser 5 Pump 6 Shield plate

Claims (1)

(57) [Claims] Claims: 1. A device having a capability of transmitting light in a wavelength region having a minimum wavelength of 450 nm or more and a maximum wavelength of 600 nm or less ,
A light- shielding plate for water treatment equipment, wherein the light transmittance is 0.005% or more .