JP2003266085A - Operation method for manganese catalytic column - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method for a manganese catalytic column capable of simply restoring treatment efficiency even if iron and manganese oxides adhere to a packed bed. <P>SOLUTION: At the time of usual operation, raw water is passed through the manganese catalytic column 1 as an ascending flow at a high linear velocity of 1,000 m/day or more while adding chlorine to the raw water to oxidize and precipitate soluble manganese in the raw water before filtering the raw water by a separation membrane 3. When the treatment capacity of the manganese catalytic column 1 lowers, the raw water is passed as the ascending flow at a linear velocity higher than the linear velocity at the time of usual operation but lower than 3,500 m/day to wash off the adherend on a manganese oxide catalyst. The manganese oxide catalyst comprises particles with a specific gravity of 3 or more, and high linear velocity ascending flow washing can be performed without generating the outflow of the catalyst. Washing is preferably performed so as to be divided into one or more times. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for operating a manganese contact tower used in a water purification plant or the like.

[0002]

2. Description of the Related Art River water and groundwater used as a water source may contain soluble manganese and iron. Cause. A contact manganese sand filtration method using a manganese contact tower is known as such a method for treating raw water for purification.

In this contact manganese sand filtration method, chlorine is continuously added to raw water containing soluble manganese while water is passed as a downflow to a packed bed of manganese dioxide-coated filter sand (manganese sand). Is the way. Soluble manganese is rapidly oxidized by chlorine using manganese dioxide as a catalyst to become manganese dioxide and is bonded to the surface of the existing manganese sand. In this way, while the raw water is flowing downward in the packed bed of manganese sand, the soluble manganese is oxidatively precipitated and captured, and at the same time, the suspended matter in the raw water is also filtered by the packed bed of manganese sand. Will be removed.

However, since the contact manganese sand filtration method is a method of oxidizing and precipitating manganese in raw water and removing it together with suspended matter in a packed bed of manganese sand, in order to secure the removal rate of manganese and suspended matter. In order to achieve this, the linear velocity of the raw water passing through the packed bed must be as low as 150 m / day. Therefore, when the amount of treated water is large, there is a problem that a very large tank is required. Further, when the turbidity of the raw water increases, such as during rainfall, the packed bed is likely to be clogged, and therefore backwashing must be frequently performed, which requires a lot of trouble in operation management.

Therefore, the present inventors have added chlorine to raw water containing manganese while passing it through a manganese contact tower filled with a manganese oxide catalyst as an upward flow of a high linear velocity of 1000 m / day or more. We developed a method to remove oxidative precipitates by oxidative precipitation of soluble manganese in raw water and membrane filtration of the water passing through the manganese contact tower. In this method, since the packed bed of the manganese oxide catalyst serves as an expanded bed, there is no clogging due to suspended matter in the raw water, the facility can be downsized, and the operation management is easy.

However, depending on the operating method, such as when operating at a low chlorine concentration in order to suppress trihalomethane generation, iron and manganese oxide adhere to the packed bed of the manganese oxide catalyst, and the treatment efficiency gradually decreases. There were cases. Therefore, in such a case, it is necessary to take out the manganese oxide catalyst from the manganese contact tower and replace it, or to wash and classify the catalyst, and the operation management is easy. The advantage of was sometimes impaired.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and allows raw water containing manganese to be purified by a small-sized facility without causing clogging due to turbidity in the raw water. Moreover, iron is contained in the packed bed of the manganese oxide catalyst,
The purpose of the present invention is to provide a method for operating a manganese contact tower that can easily recover the treatment efficiency even if the manganese oxide adheres.

[0008]

The method of operating a manganese contact tower according to the present invention, which has been made to solve the above-mentioned problems, is a method for operating a manganese contact tower filled with a manganese oxide catalyst at 1000 m while adding chlorine to raw water. When water is passed as an upward flow at a high linear velocity of at least 1 / day to oxidize and precipitate soluble manganese in the raw water, and the processing capacity of the manganese contact tower decreases, the linear velocity during normal operation exceeds 3500 m. This is characterized in that raw water is passed as an upward flow of a higher linear velocity up to / day to wash the deposits on the manganese oxide catalyst.
It should be noted that it is preferable to use particles having a specific gravity of 3 or more as the manganese oxide catalyst to enable upward linear flow washing at a high linear velocity without causing the catalyst to flow out. It is preferable to carry out the washing in step 2 dividedly.

According to the present invention, during normal operation, raw water containing manganese is passed through the manganese contact tower as an upward flow of a high linear velocity of 1000 m / day or more. Water purification treatment is possible without causing blockage. In addition, when the processing capacity decreases, raw water is passed as an upward flow of a linear velocity exceeding 3500 m / day, which exceeds the linear velocity during normal operation, to wash the deposits on the manganese oxide catalyst. Therefore, it is not necessary to take out the manganese oxide catalyst and replace it, or to wash and classify the taken out manganese oxide catalyst, and the treatment efficiency can be easily recovered.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below. In FIG. 1, reference numeral 1 denotes a manganese contact column having a packed bed 2 therein, and the packed bed 2 is packed with particles of a manganese oxide catalyst. It is preferable to use a manganese oxide catalyst having a specific gravity of 3 or more. For example, it is preferable to use a manganese oxide catalyst having a beta-type crystal structure having a specific gravity of 3.48. The specific gravity of manganese sand used in the conventional contact manganese sand filtration method is 2.36.
Is. A manganese oxide catalyst having a beta type crystal structure has a large surface area of 10 to 30 m ² / g, and is also preferable in this respect.

Raw water containing manganese is continuously added with a necessary amount of chlorine, and 1000 m / m from the bottom of the contact tank 1 is supplied.
Water is passed as an upward flow of high linear speed for more than a day. Soluble manganese in raw water is rapidly oxidized by chlorine using manganese oxide as a catalyst, and is oxidized and precipitated as an insoluble oxidization product of manganese dioxide. Practically preferable linear velocity is 1000-2
It is 500 m / day, and the catalyst particles in the packed bed 2 are in a fluidized state to form an expanded bed. If the linear velocity is less than 1000 m / day, the flow of the catalyst particles becomes insufficient and the turbidity of the raw water increases, such as during rain, which may cause blockage. Conversely, if the linear velocity exceeds 2500 m / day, the raw water Since the contact time with the catalyst particles becomes short, the packed bed 2 must be made quite high.

The water passed through the packed bed obtained by oxidizing the soluble manganese into manganese dioxide in this way is then separated into the separation membrane 3.
Be led to. The type of the separation membrane 3 is not particularly limited, but since the backwashing operation is easy, the amount of treated water is large, and it is resistant to high turbidity, the turbidity is not captured in the contact tank at such a high linear velocity. It is preferable to use a ceramic membrane that allows direct membrane separation. In this embodiment, a ceramic MF membrane having a pore size of 0.1 μm is used. If the water passing through the packed bed is subjected to membrane filtration with this separation membrane 3,
Insoluble manganese that has been oxidatively insolubilized in the packed bed 2 of catalyst particles can be reliably removed. At the same time, the suspended matter contained in the raw water is also filtered by the separation membrane 3 to obtain clear treated water. This treated water can be used as clean water.

Normal operation is continued as described above,
Depending on the operating method, iron is used in the packed bed 2 of the manganese oxide catalyst,
Adhesion of manganese oxide may occur, and the treatment efficiency may gradually decrease. In the present invention, in such a case, the raw water is passed through the packed bed 2 as an upward flow of a linear velocity exceeding 3500 m / day, which exceeds the linear velocity during normal operation. That is, if the linear velocity during normal operation is 1000 m / day, 1000 m
/ Line up to 3500m / day, the linear speed during normal operation is 1
If it is 500m / day, it will exceed 1500m / day and 35
High linear velocity up to 00m / day.

As the upward flow of such a high linear velocity, the packed bed 2
Passing water through is normally not done because it can lead to washout of the packing. However, since the specific gravity of the manganese oxide catalyst used in the present invention is as large as 3 or more, 350
Even if raw water is passed through the packed bed 2 as an upward flow of a very high linear velocity up to 0 m / day, the manganese oxide catalyst does not flow out. By this water passing, the manganese oxide catalyst is vigorously stirred, and the catalyst particles come into contact with each other, whereby the deposits on the surface can be separated and washed. Therefore, according to the present invention, the treatment capacity of the packed bed 2 of the manganese oxide catalyst can be easily washed in a short time without taking the catalyst out of the column as in the conventional case. Further, as shown in Examples described later, the cleaning effect can be enhanced by performing the cleaning not at once but in a plurality of times with a short rest time.

In the present invention, no special equipment for cleaning is required, and it is only necessary to increase the capacity of the raw water pump 4. The drainage water at the time of washing may be discarded, but it can also be directly recovered by filtration through the separation membrane 3.

[0016]

Example (Example 1: Linear velocity at the time of cleaning) The raw water containing chlorine was added to the manganese contact column described as an embodiment.
A normal operation of passing water at a linear velocity of 00 m / day was carried out for one month, and a cleaning experiment was conducted when the catalyst activity dropped to 70% of that at the start of the operation. As shown in Table 1, the washing rate was variously changed and the catalyst activity after washing was measured. As shown in Table 1, the recovery of the catalytic activity is not observed when the linear velocity at the time of washing is the same as that in the normal operation, but the recovery of the catalytic activity becomes large when the linear velocity at the time of washing exceeds 2000 to 3500.
A marked recovery was observed at m / day. But 4
At 000 m / day, the catalyst flowed out and it became impossible to operate. The cleaning time may be very short.

[0017]

[Table 1]

(Example 2: Outflow of catalyst) Manganese oxide catalyst (particle size 0.5 to 1 mm, specific gravity 3.48, surface area 15 m ² /
g) and conventional manganese sand (particle size: 0.6 to 1.5 mm, specific gravity: 2.36, surface area: 1 m ² / g) are packed in a manganese contact tower, and the linear velocity of the upward flow is variously changed. The outflow rate was measured. The result is shown in FIG. Conventional manganese sand cannot be washed at a linear velocity exceeding 2000 m / day because it will flow out with a small particle size, but when a manganese oxide catalyst is used, it will flow out at a linear velocity of up to 3500 m / day. It was confirmed not to do.

(Embodiment 3: Split cleaning) Normal operating linear velocity is 1
The washing of the manganese contact tower at 500 m / day was performed in two steps at a linear velocity of 2000 m / day as shown in FIG. 3a. One wash duration is 3 minutes, rest time is 1
Minutes. The turbidity of the effluent from the manganese contact tower during this wash was as shown in Figure 3b and the catalytic activity was restored as shown in Figure 3c. By performing the divided washing in this way, the turbidity of the outflow water does not increase so much, and membrane filtration is possible. On the other hand, the catalyst activity could be recovered to 90% or more even after washing for 3 minutes at a linear velocity of 2500 m / day, but as shown in Fig. 4, the turbidity of the effluent during washing increased. However, membrane filtration became difficult. By performing the divided washing in this way, it becomes possible to perform membrane filtration of the washing water.

[0020]

As described above, according to the operating method of the manganese contact tower of the present invention, during normal operation, the raw water containing manganese is purified by a small-sized facility without causing clogging due to suspended matter in the raw water. Can be processed. When iron and manganese oxide adhere to the packed bed of the manganese oxide catalyst as a result of continuous operation, turbulence is increased by passing raw water as an upward flow of a higher linear velocity up to 3500 m / day. The contact effect between the catalysts due to the flowing flow and the cleaning effect of the high linear velocity upward flow are generated, and the deposit can be separated. At this time, it is possible to discharge dust (suspended matter) that could not be discharged during normal operation. As a result, according to the present invention, the processing efficiency can be easily recovered without taking the catalyst out of the column as in the conventional case.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the linear velocity and the outflow rate of catalyst in Example 2.

FIG. 3 is a graph showing data of divided cleaning in Example 3.

FIG. 4 is a graph showing data of non-division cleaning in Example 3.

[Explanation of symbols]

1 manganese contact tower, 2 packed bed, 3 separation membrane, 4 raw water pump

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01D 9/02 615 B01D 9/02 615A 615Z 621 621 625 625C 625D B01J 23/34 B01J 23/34 M C02F 1 / 76 C02F 1/76 Z (72) Inventor Nobuhiro Aoki No. 2-56, Suda-cho, Mizuho-ku, Nagoya, Aichi Prefecture Incorporated Insulator Nihonmoto F-term (reference) 4D038 AA01 AB66 AB89 BA02 BA04 BA06 BB16 BB17 4D050 AA03 AB55 BB04 BC06 BD02 BD06 CA09 4G069 AA03 CA05 CA07 CA11 EA02Y

Claims (3)

[Claims] 1. While adding chlorine to raw water, water is passed through a manganese contact tower filled with a manganese oxide catalyst as an upward flow of high linear velocity of 1000 m / day or more to oxidize and precipitate soluble manganese in raw water. In addition, when the manganese contact tower's processing capacity declined, the linear velocity during normal operation was exceeded and 350
A method for operating a manganese contact tower, characterized in that raw water is passed as an upward flow of a higher linear velocity up to 0 m / day to wash deposits on the manganese oxide catalyst. 2. The method for operating a manganese contact tower according to claim 1, wherein particles having a specific gravity of 3 or more are used as the manganese oxide catalyst to enable upward linear flow washing at a high linear velocity without causing the catalyst to flow out. . 3. The method for operating a manganese contact tower according to claim 1, wherein the washing when the treatment capacity of the manganese contact tower is lowered is divided into a plurality of times.