JPS58196814A - Backwashing method in electromagnetic filter type filter tower - Google Patents

Abstract

PURPOSE:To exclude fine particles in good efficiency, by carrying out backwashing operation after water containing fine particles having zeta potential with inverse polarity with respect to fine particles in raw water is passed through and recirculated to a filter tower. CONSTITUTION:The supply of raw water is stopped while valves 11, 12 are closed. In the next step, an electromagnetic coil 3 is stopped while valves 13, 14 are closed and water in a filter tower 1 is pressed out by usual backwashing operation. The valves 13, 14 are closed while valves 21, 22 are opened and water containing Fe3O4 being fine particles having negative zeta potential is passed through and recirculated to the filter tower 1 for 30min. After the passage and the recirculation of the injected fine particle-containing water is finished, the valves 21, 22 are closed while the valves 13, 14 are opened to carry out backwashing operation again to press out water in the filter tower 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an electromagnetic filter type F, i, which is formed by filling the inside of a filtration tower with a magnetic material and arranging an electromagnetic coil around the outside of the filter tower.
The present invention relates to a backflow method for an electromagnetic filter type filtration tower in which fine particles captured and accumulated by the magnetic material are efficiently removed from the filtration field in the M tower.

In general, in a T-magnetic filter type P filter, a magnetic material is placed horizontally inside the P filter, and a magnetic field is generated by an electromagnetic coil placed around the filter tower. It adsorbs and captures paramagnetic and ferromagnetic fine particles contained in the #
It separates and removes fine particles from raw water. Therefore, p
When fine particles are accumulated in the filled magnetic material due to the operation of the passing tower,
This will lead to an increase in the pressure loss of the filtration tower and a deterioration of the quality of the treated water. The tests are carried out at reasonable time intervals.

Figure @1 is an explanatory diagram of a water treatment flow using a typical electromagnetic filter type filtration tank.Jg essential points will be explained below regarding the normal backwashing method implemented in this water treatment flow.

Raw water containing fine particles in the camphor of P-tower L is supplied to the electromagnetic filter from the lower part of filtration tower 1 with valve 11 set to -. This electric value filter includes a magnetic body 2 such as magnetic thin wires and a magnetic porous plate filled in F, i[1, and the magnetic body 2 is excited by an electromagnetic coil 3. The raw water flowing into the filtration field 1 is separated and removed by stratified trapping by the excited magnetic material 2, in which N magnetic and ferromagnetic fine particles are separated and removed. It is discharged as street treated water.

The backwashing operation for removing the fine particles captured by the magnetic body 2 from the p-transistor 1 by the water flow of the raw water is carried out according to the procedure described below. First, the valves 11 and 12 are closed to stop the flow of raw water, and the electromagnetic coil 3 is stopped. Then valve 13.1
4 is opened, pressurized air of 3 to 5 kg/crm2 is supplied from the upper part of the filtration tower 1 from the valve 13, and the water in the Pi7Ii tower 1 is passed all at once through the valve 14t to be fed into the air. Discharge to the outside of r1. At this time, the electromagnetic filter is backwashed,
The backwash flow rate reaches 4 to 10 times the flow rate during normal water flow, and the effect of creating a gas-liquid mixed flow often forcibly separates fine particles captured by the magnetic material 2 and reverses the flow rate. It is discharged to the outside of the transit tower along with the washing water.

FIG. 2 is a graph showing an example of the relationship between the backwashing efficiency and the number of times of backwashing according to the backwashing method performed according to the above-described procedure.

However, the backwashing efficiency is defined by the following formula: 0 W(-): Backwashing effective flow A: Amount of particles captured by the magnetic material B: Amount of particles removed by backwashing N: ilp
As is clear from the number of washings in Figure 2, the backwashing efficiency decreases as the number of backwashes N increases. As a result, this will lead to adverse effects such as an increase in pressure loss in the filtration tower and deterioration of the quality of the treated water.In particular, if there are many paramagnetic particles in the raw water, the magnetic force will have little ability to capture the paramagnetic particles. This will further worsen the treated water quality.

This invention was made in view of the above-mentioned actual situation, but one of the reasons why the backwashing efficiency decreases due to the increase of fine particles that cannot be removed by backflow on the surface of the magnetic material is that the fine particles possess on the surface. This is based on the knowledge that mamarugame has a strong adhesion to magnetic materials due to its surface charge.

In other words, when backwashing an electromagnetic filter in a filtration tower, the present invention uses water in the filtration tower that contains particulates that has a zetta potential of opposite polarity to the surface charge of the particulates captured by the magnetic material. The method is characterized in that water is passed through the surface of the magnetic material to neutralize the particles trapped on the surface of the magnetic material, and then a backwashing operation is performed.

Embodiments of the present invention will be described in detail below with reference to FIGS. 3 and 4.

α-F.20. which is a fine particle having a positive zeta potential under the conditions shown in Table 1 below. When the raw water containing the
It dropped to 0-9. Therefore, according to the procedure described below, one of the methods of the present invention is
The backwashing method according to the example was carried out. First, in FIG. 3, the supply of raw water was stopped and the valves 11 and 12 were closed. Next, the electromagnetic coil 3 was stopped, the valves 13 and 14 were opened, and the water in the filter tower 1 was pushed out by a normal backwash operation. Subsequently, valves 13 and 14 were closed, valves 21 and 22 were opened, and water containing F.,04 containing fine particles having a negative zeta potential was passed through and circulated for 30 minutes under the conditions shown in Table 2 below. . At this time, the electromagnetic coil 3 may or may not be excited, but if the particles to be injected are ferromagnetic particles as in this embodiment, the electromagnetic coil 3t is excited to make the injected particles into a magnetic material. 2. After the circulation of the injected fine particle-containing water is completed, the valve 21.
22 was closed, valves 13 and 14 were opened, and the backwashing operation was performed again to push out the water in the filter tower 1. When the amount of fine particles in the backwash water discharged by this operation was added ft#11,
It was found that the amount was 20% higher than that of the injected microparticles. Therefore, according to the embodiment of the present invention described above, it was confirmed that the particulates remaining in the magnetic material of the electromagnetic filter were removed.

Table 1 Table 2 Next, under the conditions shown in Table 3 below, raw water containing F. When the washing operation was performed, the backwashing efficiency decreased to SOs after 5 times of backwashing. Then, as in the previous example, rC1 is now heated under the conditions shown in Table #I4 below, with fine particles having a positive potential, 6ru a-F.
・20. After circulating the water containing water for 30 minutes, the same backwash operation as described above was performed, and it was found that the amount of fine particles in the discharged backwash water was 15% greater than the amount of injected fine particles. Therefore, in this example as well, it can be confirmed that the particulates remaining in the magnetic material of the electromagnetic filter are removed.

I/43 Table 4 Note that if the raw water to be treated contains fine particles with both positive and negative zeta potentials, injection of fine particles with negative zeta potentials and injection of positive zeta potentials are performed sequentially. Either injecting fine particles that have a high zeta potential, electrically neutralizing both types of fine particles, and then performing a backwash operation, or
Alternatively, water containing particles having a zeta potential of opposite polarity to the charge of the particles remaining in the largest amount in the magnetic body 2 of the electromagnetic filter during a normal backwashing operation may be injected.

As explained above, by carrying out the backflow method according to the embodiment of the present invention, it is possible to efficiently remove fine particles remaining in the magnetic material packed in the electromagnetic filter m filtration tower.

FIG. 4 is an explanatory diagram of the backwashing method according to the present invention, although it differs from that shown in FIG. 3 in the configuration of the electromagnetic filter used. The electromagnetic filter shown in FIG. 4 differs from the electromagnetic filter shown in FIG. 3 only in that the electromagnetic coil is divided into coils 3A, 3B, and VC, and other points are common.

The procedure for carrying out the backwashing method according to this embodiment in this filtration tower 1 will be described below.

First, the supply of raw water is stopped and the valves 11 and 12 are closed.

Next, coil 3m and 3Bl are stopped, valves 13 and 14 are opened, and water in the PV passage tower 1 is pushed out by backwashing operation. Subsequently, only the coil 3B is energized, and the valves 21 and 22 are opened so that the reverse polarity is positive depending on the polarity of the particles remaining on the magnetic body 2 of the electromagnetic filter.

Water containing fine particles having a certain zeta potential is passed through and circulated. The injected fine particles gradually adhere to the magnetic body 2, and most of them are captured by the excited coil 3B.
When the injected fine particles are ferromagnetic, the injected fine particles are almost completely captured in this part and do not leak into the circulating water. After the circulation of the injection water is completed, the valves 21 and 22 are closed and all electromagnetic coils are stopped. So valves 13 and 14
A backwash operation is performed at tN to push out the water in the filter tower 1.

According to the embodiment described with reference to FIG. 4, most of the injected fine particles are captured by the excited coil 3B at the top of the magnetic material 2, so the injected fine particles are removed during the backwashing operation. Efficiently contact the fine particles remaining on the magnetic material,
In addition to having the effect of promoting electrical neutralization, PJ using circulating water containing injected fine particles! This has the effect of preventing contamination at the outlet of the first column.

As understood from the above explanation, according to the present invention, 1
jLd1 filter mvs Particulates remaining in the magnetic material packed in the filtration tower can be efficiently removed, an increase in pressure loss in the filtration tower can be prevented, and the quality of treated water can be kept stable during discharge operation.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional backwashing method in an electromagnetic filter type filtration tower, Fig. 2 is a graph showing backwashing performance by the conventional backwashing method, and Figs. 3 and 4 are an illustration of an electromagnetic filter type according to the present invention. - It is an explanatory diagram of a backwashing method in a passing column. 1 ・'fIL magnetic filter plate filtration tower, 2...magnetic material,
3° electric coil, 11-14, 21, 22... valve. Figure 1 Figure 2 (%) Figure 3 Figure 4

Claims (1)

[Claims] 1. In an electromagnetic filter type filtration tower in which an electromagnetic coil is arranged around the outer periphery of a filtration tower filled with a magnetic material,
A method for removing particulates captured by a magnetic material from the filtration tower by a backwashing operation after water flow through the ti11, and before the backwashing operation, particulates having a zeta potential of opposite polarity to the particulates in the raw water are removed. A method of backwashing in an electromagnetic filter type filter tower, which involves circulating water containing water through the filter tower and then performing a backwash operation. 2. *Special iPf rust-seeking range No. 1 characterized in that the electromagnetic coil of the electromagnetic filter is excited when circulating particulate-containing water having a zeta potential of opposite polarity to the polarity of the particulates in the water through the filtration tower. A backwashing method in an electromagnetic filter pear filter tower according to item 1. 3. In the electromagnetic filter mr passage tower, which has an electromagnetic coil 1 divided into several pieces arranged around the outer periphery of PAQi filled with a magnetic substance, after the raw water has been passed through for operation, it is captured by the magnetic substance by a backwashing operation. In this method, excitation of the electromagnetic coils except for some electromagnetic coils is stopped before the backwashing operation, and in this state, zeta particles with a polarity opposite to that of the particles in the raw water are removed. A method of backwashing in an electromagnetic filter type tower, characterized in that water containing particulates having a potential of /c is circulated through a filtration field, and then excitation of all electromagnetic coils is stopped to perform a backwash operation.