JPH02115005A - Filtration apparatus for suspended solid - Google Patents

Abstract

PURPOSE:To continue filtration for long hours by providing a filter device with at least two filter layers, i.e., the initial and final layers, the former being filled with a fiber filter material unchanged in its void rate during water passage and consisting of nonwoven water resisting fibers and the latter being filled with granulated filter material. CONSTITUTION:This filtration apparatus 1 is provided with at least two filter layers 4 and 5. The filter layer 4 for passing drainage therethrough at the initial filtration stage consists of a plurality of water resisting fibers 3 (e.g., plastic fibers) in the form of a nonwoven fabric and is filled with the fiber filter material 2 whose void rate is not changed substantially during water passage. The filter layer 5 for passing the drainage therethrough at the final filtration stage is filled with a granulated member such as zeolite. As a result, the filtration can be performed for long hours at a high filtration velocity and the filtrate containing the suspended solids of lower concentration can be obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a device for separating suspended solids (hereinafter referred to as SS) in water and wastewater by rapid filtration, and is applicable to urban sewage, industrial wastewater, etc. The present invention relates to an SS separation device suitable for application to the filtration of organic wastewater.

[Prior Art] A rapid filtration device using sand as a filter medium is used to remove SS in advanced treatment of water and wastewater. However, conventionally, rapid filtration devices have been installed for treatment of industrial water, biological treatment in wastewater treatment process, or treatment after coagulation and sedimentation, and have been adopted in places where SS in inflow water is relatively low. The reason for this is that when a device using sand as a filter medium is applied to water with a high concentration of SS, SS accumulates on the surface of the filter layer for a short period of time, causing a rapid increase in filtration resistance, which requires frequent backwashing of the filter layer. This is because it was extremely inefficient and therefore difficult to implement. However, if the rapid filtration device can be applied to water with a high concentration of SS, its range of applications will expand, and rapid filtration can be utilized as a useful unit operation in water treatment.

With the aim of developing such new applications, an improved rapid filtration device that can be applied to water with high SS concentrations has recently been developed (Proceedings of the 21st Sewerage Research Conference, 1).
76-178, 1984).

FIG. 6 is a sectional view of the improved rapid filtration device.

In FIG. 6, this device has an effective diameter of 0.4 mm in the main body 21.
A sand layer 22 filled with 25 cm of sand of 5 mm (uniformity factor 1.5) is provided, a lower water collection device 23 is provided at the bottom of the sand layer 22, and a lower water collection device 23 is provided 1.2 m above the sand layer 22. Level sensor 2 detects the water level to start washing
4 are provided. A raw water inflow pipe 25 is provided at the top of the device body 21, a filtrate water discharge pipe 26 is provided below the lower water collection device 23, and a backwash water discharge pipe 27 is provided between the sand layer 22 and the level sensor 24. , which constitutes the main part.

In the apparatus configured in this manner, water flowing in from the raw water inflow pipe 25 passes through the sand layer 22, ss is captured, and is discharged from the filtered water discharge pipe 26. At this time, if the SS concentration in the raw water is high, a large amount of SS will be captured and accumulated on the surface layer of the sand J122 in a short time, increasing the filtration resistance. For this reason,
By periodically blowing air in small increments from the lower water collecting device 23 and suspending the SS accumulated on the surface of the sand layer 22, a rapid increase in filtration resistance is suppressed and filtration can be continued. Although filtration continues in this manner, the filtration resistance gradually increases and the water level rises, and when this water level reaches the height of the level sensor 24, backwashing of the sand layer 22 is started.

The results of treating effluent from a primary sedimentation tank at a sewage treatment plant using this device are shown in Table 1. Here, only the average value of the experimental results will be described.

Table 1 Results of filtration experiments using conventional technology As shown in Table 1, this device allows continuous filtration of water with a high SS concentration, such as effluent from a primary sedimentation tank, for about 4 hours. It has become.

It has been demonstrated that even wastewater with a high SS concentration can be treated by rapid filtration, and the BOD load in the next treatment step, the biological treatment step, can be significantly reduced.

[Problems to be Solved by the Invention] Although the above-mentioned prior art is a technology that enables the application of granular filter media to the filtration of wastewater with a high SS concentration, it does not essentially solve the drawbacks of the sand layer.

That is, even if air is periodically blown into the sand layer in order to suppress an increase in the water flow resistance of the sand layer, it does not make it possible to continue filtration for a long time, and the filtration time has not been extended satisfactorily. Therefore, since the duration of filtration is still short, there is a problem that the ss capture ability is small and a large amount of water is required for backwashing. Therefore, it has been desired to develop a more efficient rapid filtration device.

An object of the present invention is to solve the above-mentioned problems and provide an SS separation device that can continue filtration for a long time.

[Means for Solving the Problems] In order to achieve the above object, the ss separation device of the present invention includes at least two filter layers in the device main body, and a filter layer at the initial stage of filtration through which wastewater first passes. The layer (hereinafter referred to as the "initial shallow layer") is filled with a fiber filter material in which a large number of water-resistant fibers are formed in a non-woven manner and whose porosity does not substantially change during water flow, and the final stage of filtration is where wastewater passes through after M. The filter layer (hereinafter referred to as the final layer) is filled with granular filter media.

The fibrous filter medium is made by bending water-resistant fibers such as curling them to make them elastic, and forming the bent fibers into a non-woven material.The water-resistant fibers forming the fibrous filter medium include plastic fibers, Use metal fiber, etc.

Granular filter media include sand, anthracite, synthetic resin particles,
Activated carbon, zeolite, various ceramics (preferably those with low bulk density such as hollow ones), or a combination of these are used.

[Function] As mentioned above, SS is applied to the filter layer filled with sand, which is a granular filter medium.
When high-concentration wastewater is passed through water, the filter layer becomes clogged in a short time and filtration cannot continue, but SS
If the concentration of wastewater is low, filtration can be continued for a long time. The present invention, which makes it possible to obtain filtered water with a very low SS concentration, has been made to take advantage of the characteristics of such a granular filter medium, and includes at least two filter layers with different functions. That is, the filter layer mainly contains large S
It is composed of a combination of a filter layer filled with a fibrous filter medium suitable for removing S and a filter layer not filled with a granular filter medium suitable for removing fine SS. For this reason, rough filtration of wastewater is performed in the filter layer filled with fibrous filter media, so the concentration of SS in the waste water that passes through the next filter layer filled with granular filter media decreases significantly. The load on the layer is reduced. Therefore, even with a filter layer filled with granular filter media, filtration can be continued for a long time and the filtration speed can be increased.

Since the fibrous filter medium is made of non-woven water-resistant fibers, it has a very large porosity, and therefore has very low resistance to water flow and is less likely to become clogged.

For this reason, it is a filter medium suitable for filling the filter layer of the coarse filtration stage, which mainly removes large SS.

The granular filter medium is determined by the particle size distribution of SS in the wastewater to be filtered, the planned value of water flow resistance, or the planned value of the SS concentration in the filtrated water. It is desirable to use particles with as large a particle size as possible 0 Normally 5
The preferred particle size is approximately 1 to 1 mm. When the particle size is less than 11, the removal rate of fine SS is good, but it is not preferable because the pressure drop is large and the degree of clogging of the filter layer is large, and when it exceeds 5 cities, the degree of clogging of the filter layer becomes small, but The removal rate of fine SS decreases.

[Example] FIG. 2 is an explanatory diagram schematically showing a fiber filter medium used in the present invention. This fiber filter medium 2 was discovered through many filter medium selection experiments, and is made by coating and bonding a large number of bent plastic fibers 3, which are water-resistant fibers, with a binder to form a three-dimensional mesh-like structure. It is formed into a woven fabric.

The diameter of the fibers 3 constituting the fiber filter medium 2 is between 100 denier (approximately 0.091 denier) and 10,000 denier (approximately 0.91 denier).
mm). The porosity of the fiber filter medium 2 is 7
Select in the range of 0% to 99.5%.

The diameter of the fibers 3 constituting the fiber filter medium 2 and the porosity of the fiber filter medium 2 were determined as follows based on the results of a filter medium selection experiment.

Regarding the diameter of the fibers 3, if the filled fiber filter medium 2 is compressed and reduced in volume during water passage, the porosity will decrease and the filtration performance will change, which is not preferable. For this reason, the fibers 3 need to have enough strength to prevent the fiber filter medium 2 from being substantially compressed during water passage, and the diameter of the fibers 3 that meets this condition needs to be about 100 deniers or more. However, if the fibers 3 become too thick, the effective surface area per unit volume of the filter medium decreases, and the filtration efficiency deteriorates. Thus, in consideration of the relationship with filtration efficiency, it is desirable that the diameter of the fibers 3 be 10,000 deniers or less.

The porosity of the fibrous filter medium 2 was determined on the premise that the water flow resistance would not suddenly increase in a short period of time during water flow and that the SS removal rate would be good. If the porosity of the fiber filter medium 2 is less than 70%, the water flow resistance will increase rapidly after several hours after water flow, so the purpose of the present invention cannot be achieved, and if the porosity is 99.5%.
If it exceeds this, the removal rate of SS will be insufficient and the function as a filter medium will be insufficient. Therefore, the preferred porosity of the fiber filter medium 2 is 70.
% to 99.5%.

Next, the results of a performance test of the above-mentioned fiber filter medium will be explained.

FIG. 3 is an explanatory diagram of an apparatus in which a performance test of the fiber filter medium used in the present invention was carried out. Inner diameter 10c+++, height 2.5
In the vertical device body 1 made of acrylic resin, the fiber filter medium shown in FIG. 2 is spread and filled to a required height to form a shallow layer 15. 9 is a wastewater inflow pipe that supplies wastewater; 10 is a filtered water discharge pipe that also serves as a backwash water supply pipe; 1
1 is an air blowing pipe used during backwashing, 12 is a backwash water discharge pipe, and 13 is a backwash water collection pipe.

This device supplies wastewater from a wastewater inflow pipe 9 at a flow rate that matches the filtration speed, and discharges filtrate from a backwash water supply pipe/filtrate discharge pipe 11 at a flow rate that is the same as the wastewater supply flow rate. and,
When filtration continues for a long time and the pressure drop reaches a certain limit, the shallow layer 15 is backwashed.

In backwashing, filtration is interrupted while the wastewater remains in the device main body 1, and air is blown from the air blowing pipe 11 to peel off the SS attached to the filter medium and suspend it in the accumulated wastewater. After blowing air for a predetermined period of time, the water containing SS is discharged. If one time of backwashing is insufficient, after filling the backwash water to near the upper end of the shallow layer 15, repeat the above-mentioned first operation.

(Filter Media Performance Test 1) As the test water, runoff water from the first sedimentation tank of a sewage treatment plant was passed through. As shown in Table 2, the conditions of the shallow layer were varied by changing the material of the filter medium, the diameter of the fibers, and the porosity.

Table 2 Shallow layer conditions (Filtering medium performance test 1) A large number of measured values obtained in this filtration experiment were summarized into an average value, and Experiment No. 1
The results of experiment N [L 2 are shown in Table 4,
The results of experiment N[L 3 are shown in Table 5.

In each table, the filtration duration time indicates the continuous filtration time performed in each experiment, and the final pressure drop indicates the pressure drop immediately before the end of the filtration experiment.

Table 3 Filtration experiment results (Filtering material performance test 1-Experiment No.
1) Table 4 Filtration Experiment Results (Filter Media Performance Test 1-Experiment No. 2) Table 5 Filtration Experiment Results (Filter Media Performance Test 1-Experiment No.,
3) Table 3 (Experiment NIL 1, filter material is polyvinylidene chloride, fiber diameter is 500 denier, porosity is 93
%), the filter medium used in this experiment had a pressure drop of only 41 cmH2O after 15 hours of continuous filtration even when the filtration speed was increased to about 200 m/day, and the SS removal rate was also 90 m/day.
More than % are secured.

In Table 4 (Experiment No. 2, filter material is polyvinylidene chloride, fiber diameter is 4000 denier, porosity is 98%), the filter material used in this experiment has a higher SS than that of Experiment NIL1 (Table 3). Although the removal rate is slightly lower, the final pressure drop is significantly lower and the filtration duration can be extended even further.

In Table 5 (Experiment 3, filter material is stainless steel, fiber diameter is 0.60 mm, porosity is 98%), even if the filter material is changed to stainless steel, the fiber diameter and porosity are the same. Approximately the same good values as in the case of the filter medium of Na2 (Table 4) were obtained.

Next, after the above filtration experiment, the filter layer was backwashed, and the results of investigating the difficulty of cleaning the filter medium, the amount of SS captured in the filtration experiment, and the amount of water required during backwashing are shown in Tables 6 and 7. Table 6 shows the backwashing results after the filtration experiment of Experiment Na 1, and Table 7 shows the backwashing results after the filtration experiment of Experiment N [L 2. In each table, the amount of SS captured is This is a value determined from the SS concentration in wastewater and its discharge amount, and the backwash wastewater amount ratio is the ratio of the amount of water used during backwashing to the total amount of wastewater subjected to filtration treatment.

Table 6 Backwashing results (Filtering medium performance test 1 - Experiment No. 1) Table 7 Backwashing results (Filtering medium performance test 1 - Experiment No. 2 >
In Table 6 (Experiment N [L 1, fiber diameter 500 denier, porosity 93%), the SS in the first backwash wastewater was 7800.
~11350mg/Jl, which is very high, and the second time it was 21
The amount decreased significantly to 30 mg/ρ or less, indicating that SS attached to the filter medium can be easily peeled off by backwashing. In addition, the SS capture capacity is very large at 6, 4 to 9, 2 kg/m'', and the backwash drainage ratio is 0.0.
11 to 0.013, the amount of water used during backwashing can be extremely small.

In Table 7 (Experiment N (L 2, fiber diameter 4000 denier, porosity 98%), the captured amount was 6.7 to 9.1 kg.
/m2, and the backwash drainage volume ratio was 0.008 to 0.011, and good results were obtained as in the case of Experiment N (LL (Table 6)).

<Filter Media Performance Test 2> Next, the results of examining changes in pressure loss over time and changes in pressure loss with respect to filtration rate will be explained. In these experiments, in addition to the device shown in Figure 3, we also prepared a device that was filled with 60cm of anthracite and 40σ of sand to form a filter layer, and the same wastewater was passed through the two devices in parallel. A comparison was made with a granular filter medium.

In addition, in the experiment in which the granular filter medium was filled, air was not periodically blown into the filter layer as in the prior art described above.
This was done simply to compare filter media performance.

The experimental conditions for changes over time were a filtration rate of 120 m/day. The results are shown in FIGS. 4 and 5.

FIG. 4 is a diagram showing the change in pressure drop with respect to the elapsed time of filtration, and the fiber filter medium of the present invention is 1400 minutes long (approximately 24 hours).
Even after the lapse of time, the pressure loss was about 30ΩH20, indicating that filtration could be continued for an even longer time.

FIG. 5 is a diagram showing the relationship between filtration rate and pressure loss. In this experiment, the pressure drop was measured 5 hours after the start of filtration, but with the fiber filter medium of the present invention, even if the filtration speed was increased to 200 m/day, the pressure drop was about 30 cmH2O, and the filtration speed could be further increased.

As shown in the above results, the fiber filter medium used in the present invention has an extremely small pressure drop, a very long filtration time, a good SS removal rate, and a relatively large particle size S
It was confirmed that this filter material is suitable for S removal.

Next, an embodiment of the present invention incorporating the above-described fibrous filter medium will be described.

FIG. 1 is a sectional view schematically showing an embodiment of the present invention. The vertical device main body 1 is equipped with two different filter layers, with the initial filter layer 4 filled with the separated filter medium shown in FIG. A filled terminal stage 1 layer 5 is arranged. The final stage shallow layer 5 is supported by a perforated plate 6, and the initial filter layer 4 is supported by a one-layer holding material 7 that has virtually no resistance to water flow, and its upper end is fixed by a filter material fixing material 8 so as not to lift up. has been done. The diameter and porosity of the fibrous filter medium to be filled in the initial filter layer 4 and the diameter of the granular filter medium to be filled in the final shallow layer 5 are determined by the SS concentration and particle size distribution in the wastewater to be treated and the required water quality of the filtrate water. Further, the filling height of each of the initial filter layer 4 and the final shallow layer 5 is determined as appropriate according to the above conditions. Various types of piping are connected to the device main body 1, with a drainage inflow pipe 8 at the top, a filtrate discharge pipe 10 that also serves as a backwash water supply pipe, and a terminal shallow water discharge pipe 10 at the bottom. An air blowing pipe 11 inserted below the layer 5 is connected to the outer periphery of the device main body 1 near the upper end of the initial filter layer 4, and one or more backwash water discharge pipes connected to a backwash water collection pipe 13 are installed. 12 are attached to each. Further, a distributor 14 in the shape of a grid or the like is provided below the final stage shallow layer 5, so that the air blown during backwashing is dispersed over the entire surface of the filter layer.

In this embodiment, the fiber filter media filled in the initial filter layer 4 may have the same porosity, but the porosity may be sequentially decreased according to the order in which the waste water passes through. In this way, if the initial flow M4 is configured by combining fiber filter media with different porosity, it will be possible to change the flow from SS with a large particle size to S with a relatively small particle size.
S can be removed, and the load on the final stage shallow layer 5 filled with granular filter media can be further reduced. Further, an intermediate filter layer filled with a fiber filter medium having a smaller porosity than that filled in the initial filter layer 4 may be provided between the initial filter layer 4 and the final shallow layer 5.

The filtration operation of this device will be explained. Prior to the start of filtration, after closing the valves of each pipe, a predetermined flow rate of waste water is allowed to flow in from the waste water inflow pipe 9. When the wastewater reaches the upper end of the initial filter layer 4, the valve of the backwash water supply pipe/filtrate discharge pipe 10 is opened to start discharging the filtrate. The flow rate of filtrate water is set to be the same as the wastewater inflow flow rate. The wastewater mainly removes SS with large particle size in the initial filter layer 4, and passes through the final shallow layer 5 as wastewater containing only fine SS. The wastewater that has passed through the final stage shallow layer 5 has fine SS removed and becomes filtered water with a low SS concentration.

Although filtration continues in this manner, as the filtration continues for a long time, the pressure loss gradually increases, so when the pressure loss reaches a certain limit, the filter layer is backwashed. When backwashing is performed, the supply of waste water is stopped, filtration is temporarily interrupted, the valve of the filtrate water discharge pipe is closed, and air is blown through the air blowing pipe 11. At this time, the initial shallow layer 4 and the final shallow layer 5 are The SS adhering to the filter media filled in the tank becomes suspended in the stagnant wastewater. Next, backwash water is supplied from the backwash water supply pipe/filtrate water discharge pipe 10 while blowing air, and is caused to overflow from the backwash water discharge pipe 12. After overflowing for a predetermined period of time, the supply of backwash water is stopped, and the first backwash is completed. This first backwashing removes most of the SS. For the second backwash, repeat the above-mentioned first operation.

(Example 1) Same configuration as the device shown in FIG. 1, inner diameter], Ocm, height 2.
A filter layer with the conditions shown in Table 8 was provided in the 5 m long acrylic resin device main body 1, and a filtration experiment of inflow water from a primary settling tank of a sewage treatment plant was conducted. As a comparative example, a filtration experiment was also conducted in which 200 cm of the same fiber filter medium as that used in the example was filled. The results are shown in Table 9.

Table 8 Conditions for Example 1 Anthracite has an effective diameter of 4 mm Table 9 Filtration experiment results (Example 1) In Table 9, when comparing the results of the example and the results of the comparative example, it is found that SS with a particle size of 20μ or more There is no big difference in the removal of SS, and both are good, but fine SS with a particle size of less than 20μ
Regarding the removal of , it did not reach 70% in the comparative example, but 90% was ensured in the example. The difference in the removal rate of fine SS affects the overall removal rate, which is 95% in the example and only 90% in the comparative example.

(Example 2) A continuous filtration experiment was conducted using the same apparatus and the same filter layer conditions as in Example 1 for the influent water of the initial sedimentation tank of a sewage treatment plant. Further, after the filtration experiment was completed, a backwash test of the a-layer was conducted. The results are shown in Tables 10 and 11.

Table 10: Results of filtration experiments (Example 2) Table 11: Results of backwashing (Example 2) Table 10 shows the results of continuous filtration experiments. This result is the first
Comparing with the experimental results of the conventional technology listed in the table, in the conventional technology the pressure drop after 4.2 hours of continuous filtration at a filtration rate of 76 m/day is 1.2 m (water level at which backwashing starts).
In the present invention, even when the filtration speed is increased to 180 m/day, the pressure loss after 48 hours of continuous filtration is only 26 ca+H20.

In addition, the removal rate of SS is 93% compared to 75% of conventional technology.
95%, and the SS in the filtered water is 19mg/
, 5 mg/1 or less for R. in this way,
The filtration properties of the device according to the invention are very good. and,
It has the characteristics of low pressure drop, continuous filtration for a long time, and high SS removal rate, because the initial wave layer filled with fiber filter media removes most of the SS, and the granular filter media It can be seen that this is because the load on the final shallow layer that was filled is significantly reduced.

Table 11 shows the backwash results after continuous filtration experiments.

Comparing this result with the experimental results of the conventional technology shown in Table 1, the amount of SS trapped is 0.95 kg/m of the conventional technology.
"18 to 20 kg/+n", which is about 20 times greater, and the backwash drainage volume ratio is 0.13 compared to the conventional technology's 0.13.
011, which is about 1/12, and the filtration efficiency is extremely good. Note that the above values are the results when backwashing is performed at a low stage of pressure drop of about 25 to 30 cm H2O.If backwashing is started at a pressure drop of 1.2 m, as in the conventional technology, there will be a difference with the conventional technology. becomes even larger.

Note that the embodiments of the present invention are not limited to the above-mentioned examples; for example, the material of the fibers constituting the fiber filter medium is limited to polyvinylidene chloride, stainless steel, plastics such as polyethylene and polypropylene, or Other metals may also be used, and the initial wave layer can be formed not only by laying out filter media formed into cubes or rectangular parallelepipeds as shown in Figure 1, but also by forming filter media into cubes or spheres of appropriate size. It may also be filled with a molded filter medium. Alternatively, the fiber filter medium may be packed in a basket-like container, and a plurality of bags may be filled to form a filter layer, or two filter layers may be formed integrally.

[Effects of the Invention] The device of the present invention has an initial wave layer filled with a fibrous filter medium suitable for removing SS with a large particle size, and a final wave layer filled with a granular filter medium suitable for removing fine SS. Since most of the SS in the waste water is removed by the initial wave layer filled with fibrous filter media, the load on the final filter layer filled with granular filter media is significantly reduced. Therefore, the final filter layer filled with the granular filter medium does not become clogged for a long time, and filtration can be performed at a high filtration rate for a long time, and filtered water with a low SS concentration can be obtained.

As a result, it can be used in place of the initial settling tank of a sewage treatment plant, which is a device for treating wastewater with large particle size, or the settling tank after sessile biological treatment such as a rotating disk or a fluidized bed. In this case, the processing power will improve dramatically.For example,
The processing capacity of the initial sedimentation tank is generally designed to have a sedimentation rate of about 35 m/day, but if the device of the present invention is used,
Inflow water can be treated at a high filtration rate of about 0.00 m/day, and the scale of the equipment can be significantly reduced. Furthermore, the treatment efficiency of the first sedimentation tank is approximately 40% SS removal rate;
While the removal rate of BOD associated with the removal of SS is about 30%, the device of the present invention can secure a SS removal rate of 95%, and therefore BOD removal is also significant, making it easier to use in the next biological treatment process. BOD load is significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing an example 8 of the present invention,
Fig. 2 is an explanatory diagram schematically showing the fiber filter medium used in the present invention, Fig. 3 is an explanatory diagram of the apparatus in which the performance test of the fiber filter medium used in the present invention was carried out, and Fig. 4 is an explanatory diagram showing the fiber filter medium used in the present invention. FIG. 5 is an explanatory diagram showing the relationship between the filtration speed and pressure drop of the fibrous filter medium used in the present invention, and FIG. 6 is a cross-sectional view showing an example of the prior art. . DESCRIPTION OF SYMBOLS 1... Apparatus body, 2... Fiber filter medium, 3... Plastic fiber, 4... Initial filter layer, 5... Final filter layer.

Claims (3)

[Claims] (1) A device that separates suspended solids from wastewater by passing it through a filter layer, which has at least two filter layers inside the device body, and a large number of filter layers in the initial stage of filtration through which the wastewater first passes. It is filled with a fibrous filter material made of non-woven water-resistant fibers and whose porosity does not substantially change during water flow, and the filter layer at the final stage of filtration through which wastewater passes is filled with a granular filter material. Features: A device for separating suspended solids. (2) The apparatus for separating suspended solids according to claim 1, wherein the water-resistant fibers forming the fiber filter medium are plastic fibers. (3) The apparatus for separating suspended solids according to claim 1, wherein the water-resistant fibers forming the fibrous filter medium are metal fibers.