CN1119961A - Backwashing method of water treatment device using floating filter material - Google Patents

Abstract

Provides a backwashing method for a water treatment device using a floating filter material that can uniformly agitate and clean the entire area of the filter layer without damaging the filter material. This method is a backwashing method of a water treatment device that forms a floating filter layer by filling the lower side of the filter material loss prevention zone that divides the inside of the treatment tank into upper and lower filter material loss zones, and lowers the water level to the lower side of the filter material loss zone. , Release air from below the floating filter layer to fluidize the floating filter layer, thereby removing the occlusions in the floating filter layer. The whole area of the filter layer is uniform and the occlusion in the filter layer is removed in an appropriate amount, and the filtration time after backwashing is short and the treatment efficiency is high.

Description

Backwashing method of water treatment device using floating filter material

The present invention relates to a backwashing method of a water treatment device in which a floating filter material is filled under a filter material loss prevention belt dividing the inside of a treatment tank up and down to form a floating filter layer.

At present, the precision filtration method and biofilm treatment method of water treatment using floating filter materials made of plastic foam and the like are more and more widely used. The precision filtration method captures and filters SS (suspended matter) in raw water in a filter layer filled with floating filter materials, while the biofilm treatment method decomposes organic matter in raw water by microorganisms attached and proliferating on the surface of the filter material. In addition, as a treatment method using a floating filter material, there is an oil-water separation method in which the oil droplets in the raw water are aggregated and coarsened on the surface of the lipophilic filter material, and the oil is separated by floating.

In such a water treatment device, as the treatment progresses, the SS in the raw water captured in the filter layer and the increased biofilm will gradually block the gaps between the filter materials and reduce the filtration efficiency. In order to avoid blocking, the space rate is generally increased to about 98%, which limits the processing capacity as a result. If the space rate is reduced to 50-80% and the processing capacity is to be increased, it is necessary to carry out appropriate backwashing to remove the blockages that form the cause of blockage. This kind of backwashing is usually performed by releasing air and water from the bottom of the filter layer to make the filter layer flow, using the friction between the filter material particles to peel off the occlusion and vibrating the filter layer through the air bubbles to shake the blockage off the filter material particles. Afterwards, wash with water.

However, as in the case of using inorganic filter materials such as anthracite materials, the conventional backwash method in which air and water are released from the bottom of the filter layer at the same time cannot effectively and uniformly clean the entire filter layer. Not only does it cause blockage prematurely to increase the frequency of backwashing, but also the rate of backwashing water (the ratio of backwashing water to the treated raw water) reaches 30%, which reduces the processing capacity due to the need for a large amount of backwashing water.

There is also a method of stirring the filter layer with a stirrer arranged in the middle or lower part of the filter layer to remove the blockage, but it has the disadvantage of damaging the filter material. Especially in a device with a filter layer as high as 2.5-3.5m like biofilm treatment, a sufficient cleaning effect cannot be achieved. In addition, even if the filter layer is less than 1m, when treating high-viscosity wastewater containing vegetable oil, the entire area of the filter layer cannot be stirred uniformly, resulting in an increase in backwashing frequency and a decrease in treatment capacity. For this reason, fail to reach practicality with the backwashing method of stirring device.

The present invention is designed to solve the disadvantages of the prior art, and its main purpose is to provide a method for backwashing a water treatment device using a floating filter material that can uniformly agitate and clean the entire area of the filter layer without damaging the filter material.

In order to achieve the above object, the present invention provides a water treatment device using a floating filter material, which is characterized in that it is formed by filling the lower side of the filter material loss prevention belt that divides the inside of the treatment tank into upper and lower filter material loss prevention belts. The backwashing method of the water treatment device of the floating filter layer, wherein, the water level is lowered to the lower side of the above-mentioned filter material loss zone, the air is released from the bottom of the above-mentioned floating filter layer to make the floating filter layer flow, and the water in the floating filter layer Obstructions removed.

In this way, by lowering the water level to the lower side of the filter material loss prevention belt, the upper surface of the floating floating filter material is opened, and the upward movement of the upper floating filter material that has been restricted by the filter material loss prevention belt becomes easy to move. When releasing air from the bottom of the floating filter layer like this, the floating filter material in the whole area of the floating filter layer can be shaken uniformly, and the clogs such as biofilm attached to the surface of the floating filter material can be peeled off without damaging the filter material.

Example

Hereinafter, embodiments applicable to the present invention will be described in detail with reference to the drawings. Example 1

FIG. 1 shows an example of a processing apparatus of the backwashing method implemented according to the present invention. This treatment device is a biofilm treatment device using an upward flow method of floating filter material. The raw water to be treated is introduced into the treatment tank 1 from the raw water inlet 2 provided at the lower side of the treatment tank 1, and flows in the upward flow method. When passing through the inside of the floating filter layer 3, it is purified. The treated water that has flowed through the floating filter layer 3 and reached its upper side is sent out of the apparatus from the treated water outflow port 4 provided there.

The floating filter material 7 in the floating filter layer 3 li is filled in the space formed by cutting off the filter material loss prevention band 5.6 paired up and down, and the filter material loss prevention band 5 that floats up to the top is restricted by it. A prescribed space margin is reserved between the floating filter layer 3 and the following filter material loss prevention belt 6 . The floating filter material 7 is a granular body such as a plastic foam, and the surface is attached and multiplied to be a film-like microorganism, and the SS and soluble components captured by the floating filter material 7 are decomposed by the biofilm on the surface.

One side of the bottom plate of the floating filter layer 3 is provided with an air supply pipe 9, on which is attached a shower nozzle for releasing the air sent from the air blower 8 for aeration and backwashing. In addition, the lower portion of the treatment tank 1 is provided with a lower discharge port 10 for discharging excess sludge settled and accumulated during backwashing to the outside of the device.

When performing backwashing, at first, as shown in FIG. Next, as shown in (b), start the blower 8 to release air from the nozzle to fluidize the floating filter layer 3, and the biofilm on the surface of the floating filter material 7 is peeled off. In this way, about 1/3 of the microorganisms remain on the floating filter material 7, and the remaining about 2/3 is discharged outside the device as excess sludge through backwashing water as described later.

A part of the sludge composed of the peeled off biofilm etc. is left for a certain period of time, as shown in (c), settles and accumulates at the bottom, and is discharged from the lower discharge port 10 . Finally, as shown in (d), the treated water sent into the treatment tank (not shown in the figure) by the backwashing water pump 11 through the treatment water outflow port 4 will wash the sludge remaining between the floating filter materials 7 Come down and discharge from the lower discharge port 10.

In order to confirm the effect of this backwashing method, an experiment was carried out on a cylindrical treatment tank device with a diameter of 2 m and a height of 6 m, in which a floating filter layer 3 having a thickness of 3 m was formed. First, lower the water level to about 30cm below the filter material loss prevention belt 5 on the upper side, and use a blower with an air supply volume of 3.2m ³ /min and a discharge pressure of 5,000mmAq to release air from the nozzle at a speed of 3.2m ³ /min For 5 minutes, stir the flotation filter tank 3. Then, it was left to stand for 2 minutes, and the sludge peeled off from the floating filter material 7 and deposited on the bottom of the treatment tank 1 was discharged from the lower discharge port 10 . Then, use the backwash water pump 11 with a discharge capacity of 65m ³ /hour and a head of 10m to send the treated water into the treatment tank 1 at a speed of 65m ³ /H for 5-10 minutes to clean the floating filter material 7, and then upward Wash for 5 minutes in the flow mode, and the backwash is over.

In this way, the SS concentration of the entire backwash wastewater discharged is 1,800 mg/l, which is about twice the amount of sludge removed compared to 950 mg/l in the backwash method with a stirring device equipped with a rotating plate in the filter layer. In addition, immediately after backwashing, the same BOD·COD removal rate as in normal operation was shown, and it was confirmed that the transition time to backwashing was short.

The amount of backwash water used is 5% of the amount of treated water. When chemical additives such as coagulants are not injected, most of the microbial agglomerates have been settled after 30 minutes of simple settlement in the backwash drainage, because 50% of the supernatant water in the upper part has been sent back to the raw water side, and its final The backwash water rate is 2.5%. Example 2

Fig. 2 is another example of the device of the backwashing method implemented according to the present invention, showing the process of backwashing in sections. This processing device is the same as embodiment 1 and uses the biomembrane processing device of floating filter material, and difference is to flow downwards. The treated raw water is introduced into the treatment tank 21 from the raw water inflow port 22 arranged on the upper side of the treatment tank 21, and is purified while flowing downward through the floating filter layer 23. The treated water that has flowed through the floating filter layer 23 and reached the bottom thereof is sent out of the apparatus through the treated water outflow port 24 provided there.

Basically the same as shown in FIG. 1 , the floating filter layer 23 is filled with the floating filter material 7 . On the bottom plate side of the floating filter layer 23, an air supply pipe 9 with a shower head for releasing the air sent from the blower 8 is disposed. In addition, an oil discharge port 25 is provided on the upper surface of the treatment tank 21, and a lower discharge port 26 for discharging excess sludge settled and accumulated during backwashing to the outside of the device is provided at the bottom.

When carrying out backwashing, at first as shown in Figure 2 (a), the water in the tank is discharged through the lower discharge port 26 so that the water level is reduced to the lower side of the filter material loss prevention belt 5. Next, as shown in (b), the blower 8 is activated to release air from the spray head to make the floating filter layer 23 flow. Then, as shown in (c), the sludge peeled off from the floating filter material 7 after standing for a certain period of time settles and accumulates at the bottom, and is discharged from the lower discharge port 26 . Finally, as shown in (d), the treated water is sent in by the water pump 11, and the sludge remaining between the floating filter materials 7 is washed down and discharged from the upper discharge port 27.

In this embodiment, only the backwashing method for the biofilm treatment device using the floating filter material is shown, but the present invention is not limited to the biofilm treatment device, but is also applicable to the precision filter device and the oil-water separation device using the floating filter material.

As explained above, the backwashing method of the water treatment device using the floating filter material of the present invention is because the filter layer can be uniformly removed from the filter layer in an appropriate amount, and the transition time after backwashing is short and the treatment efficiency is high. . For example, the residual amount kept in the filter layer is about 1/3 of the microbial residue when using the biofilm treatment method, about 1/3 of the oil residue when using the oil-water separation method, and about 1/3 of the SS residue when using the precision filtration method. Immediately start operation with normal capacity without causing reduction of purification capacity.

In particular, the residual sludge of the biofilm treatment method, that is, the microbial agglomerates discharged by backwashing, is relatively strong. When the chemical additives are not injected into the simple sedimentation treatment, they will settle after 30 minutes. By sending the upper supernatant water back to the original water tank, It can be reduced from 30% of the previous backwashing water rate to below 3%.

figure 1

Consisting of a, b, c and d, the segments represent the process diagram for implementing the backwashing method of the present invention.

figure 2

Consisting of a, b, c and d, the subsections represent the process diagram of other water treatment devices when the backwashing method of the present invention is applicable. The symbols in the figure are explained as follows.

1 Treatment tank 2 Raw water inlet 3 Floating filter layer 4 Treatment water outlet 5.6 Filter material loss prevention belt 7 Floating filter material 8 Blower 9 Air supply pipe 10 Lower outlet 11 Backwash water pump 21 Treatment tank 22 Floating filter 3 Raw water inlet 2 Layer 24 Treatment water outlet 25 Oil outlet 26 Lower outlet 27 Upper outlet

Claims (1)

1. use the reverse washing method of the water treatment facilities of floating filtering material, it is characterized in that, the inside of treatment trough is divided into up and down filtering material run off prevent with downside filling floating filtering material and be formed with the reverse washing method of the water treatment facilities of the filter course that swims, wherein water level is reduced to the downside that above-mentioned filtering material runs off and is with, deflating from the below of the above-mentioned filter course that swims makes this filter course liquidation of swimming, and the obturator in this filter course that swims is removed.

Images