JPH0338205A - Rapid filtration device - Google Patents

Abstract

PURPOSE:To control back wash flow speed by providing a weir movable up and down at one end of a common pit for storing filtered water and installing a sensor for sensing the water level of the pit and a controller. CONSTITUTION:Raw water is flowed from a raw water pit 1 into a filter B through an inlet pipe 4, and filtered from the top downward successively passing through a first filter layer 5, a second filter layer 6 and a gravel layer 7. The filtered water is collected in a collecting layer 8, collected in a water purifying pit 8 through an inlet port 23 and stored in a purifying pit 12. The water level is rised as filtration is contained, and when the same is beyond tolerance limit, a raw water inlet syphon 2 is closed and a water discharge syphon 10 is opened, and the water in the filter is discharged out into a drain pit 11. When the water level is lowered at the top end of a back wash water discharge trough 9, because of the water level difference from the water purifying pit 12, and back wash of a filter layer is started. A stabilized back wash can be carried out by said arrangement.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the treatment of suspended solids or suspended solids (hereinafter referred to as SS) in water.
It is used in a rapid filtration device that relatively quickly removes filtrate.

[Conventional technology]

Rapid filtration is known as an effective means for quickly and quickly removing SS from water, and is one of the water treatment methods currently widely used. In this method, as the treatment continues, the filter layer made of silica sand and other materials becomes clogged, so the water to be treated (hereinafter referred to as raw water) is passed through until it becomes impossible to pass water through for treatment. An operation or process is required in which the water is interrupted and filtered water is used to wash the filtration layer upward from the bottom (referred to as backwashing or backwashing). This backwashing involves expanding the filtration layer with water flow and discharging 88 minutes, which is the cause of clogging, out of the processing device, which requires pressure, water volume, and time.

The most common method for backwashing is to store filtrated water in an amount necessary for one time of backwashing, and to supply the filtrated water with a pump for backwashing. On the other hand, there is a method in which a plurality of 8 or more filtration units are configured and when backwashing any IM unit, backwashing is performed using the amount and water pressure of the filtrated water of the remaining filtration units. It is commonly known as the "self-water backwashing type."

[Problem to be solved by the invention]

Conventional rapid filtration equipment requires a pump for the backwashing operation, or, in the so-called "self-water backwashing type", the water pressure of the filtrate water of a device other than the one in which the backwashing operation is carried out requires a pump. Since backwashing is performed using the amount of water, if the amount of filtrated water in other devices fluctuates, the backwashing flow rate becomes unstable. In addition, if the backwash flow rate is too high, the expansion rate of the filtration layer will increase, and the filter material will be discharged out of the device along with the backwash wastewater.On the other hand, if the backwash flow rate is too low, the expansion of the filtration layer will be insufficient, and the filter material Collision between particles becomes insufficient, and the original purpose of the backwashing operation, which is to discharge the suspended particles trapped in the filtration layer out of the V & device due to continued filtration, cannot be achieved. Based on past experience, the backwashing flow rate is normal. Set to about 0.8 m/min to 0.9 m/min. (When water temperature is 20℃).

Furthermore, when the water temperature drops in winter, the viscosity of the water increases, so the expansion rate of the filtration layer increases at the same backwash flow rate.
There is a fear that the filter media will flow out, and in that case, it is necessary to reduce the backwash flow rate.

In the conventional "self-water backwashing type" rapid filtration equipment, 41 is insufficient for fluctuations in the amount of filtrated water and water temperature, so the backwashing flow rate becomes insufficient and backwashing becomes insufficient, resulting in cloudy filtrate water. Phenomena such as a loss of quality were observed.

The present invention has been made in view of this.

[Means to solve the problem]

Common for collecting filtrate water from multiple rapid filtration devices.

In a device in which one of the filtration devices is backwashed using the volume and pressure of filtrated water from the other filtration device, an electric or other driving force is installed at one end of the common culvert that stores the filtrate water. A movable weir that moves up and down is installed, and a detector that automatically detects the water level in the drain and a controller that controls the movable weir move the movable weir up and down, controlling the water level in the drain, and controlling the backwash flow rate of one rapid filtration device. be controlled.

[For production]

The number n of rapid filtration devices is determined so that the required backwash flow rate can be ensured using the following formula even at the minimum amount of filtration water.

Where, n: Number of rapid filtration devices va: Required backwash flow rate (m/min) vr: Minimum filtration flow rate (m/min) Due to the arrangement of the device, the number n of rapid filtration units is an even number.n
A channel is provided in which the filtrated water from each rapid filtration location gathers to form the same water surface water level, and a movable weir is installed at any location on the channel to determine the water level of this channel. The structure is such that the entire structure can be moved up and down. The automatic weir is raised and lowered by signals from a water level meter, such as a capacitance type or an ultrasonic type, that can continuously and automatically detect the water level in the culvert, and is constantly adjusted to the appropriate level in response to changes in water temperature and filtration water volume. Ensure that the water level in the drain is maintained at a level that provides a backwashing effect.

The pressure required for backwashing of a rapid filtration device is expressed by the following formula: % h: Pressure required for backwashing (water head m) h: Pressure loss of the first filtration layer hb: Pressure loss of the second filtration layer Pressure loss h0: Pressure loss in the gravel layer (water head m) h4: Pressure loss in the water collection device (water ff m) h,: Piping pressure loss on the outflow side (water head m) (water head m〉 (water head m) In the table below , in a rapid 1134 device consisting of a filtration layer made of anthracite as the first layer and a filtration layer made of silica sand as the 2711th layer, the required backwash pressure for each backwash speed (water temperature 2
An example of calculation for 0°C) is shown below.

The numbers in column (6) of the table above indicate the backwash speed of 0.5 to 0.9 m/
Required pressure for minutes, water purification shown in Example Figure 3!
11 and the top of the backwash drainage discharge trough 9.

The standard backwashing speed at a water temperature of 20°C is 0.6 m/min, but as mentioned above, the optimal backwashing speed changes depending on the fluctuation of the water temperature, so use the interval shown in Figure 1 to determine the backwashing speed. Correct it to always obtain a constant backwashing effect.

The position of the top of the water purification channel outflow movable weir is determined so that the pressure (water level difference) obtained by the above calculation can be maintained according to the amount of filtered water and the water temperature.

Figure 2 shows the position of the top of the movable weir during filtration and backwashing when the backwash flow rate was set at 0.6 m/min.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The rapid W1 passing device of the present invention will be explained below based on an embodiment shown in the drawings.

In the figure, A is the main body of the raw water conduit, and B is the necessary number of rapid filtration devices adjacent to the main body A of the raw water conduit, one to two or more.

The raw water conduit zero body A is completely divided into upper and lower parts by a partition wall 21, and the upper side is the raw water conduit 1 and the lower side is the purified water bundle 1.
Set it to 2. Gensui J again! ! 1 has a vertical partition wall 22
Raw water flows in through! I! 3 is installed, and there is also the above-mentioned partition between raw water conduit 1 and raw water inflow conduit 3! ! A siphon pipe 2 is provided so as to straddle the raw water conduit 1 so that raw water flows into the raw water inflow flux 3 from the raw water conduit 1.

Further, a raw water inflow pipe 4 is arranged between the raw water inflow flux 3 and the rapid filtration MIIB, whereby the raw water in the raw water conduit 1 is evenly backflowed to a plurality of adjacent rapid filtration devices B. Further, the raw water is allowed to flow into each rapid filtration device B from a common raw water conduit 1 at a constant flow rate through a raw water inflow siphon pipe 2, a raw water inflow flux 3, and a raw water inflow pipe 4.

The rapid filtration device B has the 1st tjE filtration layer 5 and the 211th filtration layer from the top.
Over N6, gravel I! 17 and a water collection layer 8 are arranged in sequence, and anthracite is used as the first filter layer 5 and silica sand is used as the second filter layer 6, but the first and second filter layers are composed only of silica sand. It is also possible to do so. This first and second
The gravel N7 formed at the bottom of the filtration layer 5゜6 is for physically supporting the filtration layer 5゜6, and also for filtering water that has passed through the filtration layers 5, 6 and the gravel layer 7. Water catchment layer 8
It will be collected equally at

The water purification bundle 12 is for storing the filtered water from each rapid filtration device 1B, and for this reason, the lower part of each rapid filtration device B and the water purification bundle 12 are connected by a water hole 23 or a water pipe, and each In order to make the water level of the rapid filtration device B common, a controllable movable weir 13 is provided within the drain 12. 14 is water purification bundle 1
The water level detector 14 automatically and continuously detects the water level in the purified water bundle 12, and the weir is driven via the controller 16 to reach a preset water level. The motor 15 is controlled to move the control movable weir 13 up and down.

Therefore, when rapidly filtering raw water, raw water IJ! 1, raw water flows into the rapid filtration bag +11B through the siphon pipe 2, raw water inflow flux 3, and inflow pipe 4, and passes through the first filtration layer 5, the 211th filtration layer 6, and the gravel layer 7 in order from the upper layer of this device. It is then filtered. The filtered water is collected in a water collection layer 8,
The water is stored in the purified water bundle 12 through the inflow hole 23 . In this way, as the filtration of raw water continues, the water level in the rapid filtration device rises due to the retention of turbidity in the filtration layer, and when it exceeds the permissible limit, the raw water inflow siphon 2 is closed and the drainage siphon 2 is closed. Filter by using 10 as a leap! ! 1 The water in the device is discharged to the drain 11.

When the water level in the filtration device B drops to the top of the backwash drainage trough 9, the purified water vJ! Due to the water level difference H between 12 and 12, water purification culvert 12
The water flows back, and backwashing of the filtration layer begins. Backwashing is performed for a certain period of time with this water level difference H (pressure).

In the present invention, the water level difference H is controlled by automatically raising and lowering the movable weir 13, so that the water level difference H can be maintained properly at all times depending on the excess water amount, water temperature, and other conditions. When finishing the backwashing operation, the water level in the filtration device rises by closing the drain siphon pipe 10 and opening the raw water inflow siphon 2.
The water flows in the direction towards the water purification culvert and the filtration operation is restarted. The opening and closing of the siphon tubes 2 and 10 is automatically performed by opening and closing vacuum piping connected to a vacuum pump.

〔Effect of the invention〕

The present invention has the following effects.

■ In the device of the present invention consisting of a plurality of filtration devices, backwashing of one filtration device is performed using the w1 filtration water volume and pressure of other devices, so equipment such as a backwash pump is not required. ■ Filtration water volume , it is possible to always perform stable backwashing in response to conditions such as fluctuations in water temperature, and there is no problem due to poor backwashing.
I. Formation of mud balls within the filtration layer or obstruction of outflow of the filter medium due to excessive backwashing can be prevented.

■ Even during backwashing operations, a constant backwashing speed can be automatically maintained at all times compared to the conventional method using a fixed weir.

■ Setting any backwash flow rate as needed can be done simply by setting the position of the movable weir top.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing the correction of the optimum backwash flow rate by water temperature;
FIG. 2 is an explanatory diagram showing an example of the position of the movable weir in the present invention, FIG. 3 is a sectional view showing an embodiment of the device of the present invention, and FIG. 4 is an explanatory diagram showing an example of the effects of the present invention. . 1... Raw water bundle 2... Raw water inflow siphon 3... Raw water method dock 4... Raw water inflow pipe 5... 1st Iw filtration layer 6... 2nd layer m filtration layer 7... Support Gravel layer 8...Water collection device 9...Backwash drainage trough 0...Backwash drainage siphont...Drainage culvert 2...Water purification culvert 3...Control movable weir 4...Water level detector 5 ... Control movable weir drive motor 6 ... Controller A ... Raw water bundle body B ... Rapid filtration device Applicant: Fuso Construction Industry Co., Ltd.

Claims (1)

[Claims] In a device in which a common conduit is provided to collect filtrate water from a plurality of rapid filtration devices, and backwashing of one of the filtration devices is performed using the volume and pressure of filtrate water from other filtration devices. , A movable weir that is moved up and down by electric or other driving force is installed at one end of a common conduit that stores filtered water, and the movable weir is raised and lowered by a detector that automatically detects the water level in the conduit and a controller that controls the movable weir. A rapid filtration device characterized in that it is possible to control the water level of a culvert and the backwash flow rate of one rapid filtration device.