JP2568980B2 - Fine ceramic filter material, method for producing the same, and filtration device using the filter material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

INDUSTRIAL APPLICABILITY The present invention is effective for filtering turbid and soluble organic pollutants, ammonia ions and fungi using a single filtration tank for sand filtration. The present invention relates to a fine ceramic filter material, a method for producing the same, and a filtration device using the filter material.

[0002]

2. Description of the Related Art Conventionally, for example, water in pools and bathtubs has been exposed to organic substances (for example, fatty acid esters, saturated fatty acids, unsaturated fatty acids, proteins, etc.) secreted from the human body by humans, Contaminated by nitrogen, fine dust, E. coli, and common bacteria.

[0003] Therefore, various studies have been made on a filtration device (purification system) for saving water and heat resources by circulating and purifying such contaminated water through an appropriate filtration tank. I have. For example, in the case of a filtration device mainly for removing suspended substances in water, the following three methods can be mentioned depending on the material of the filter material loaded in the filtration tank. (1) Sand filtration method using silica sand as a filter material.

(2) A diatomaceous earth filtration method using a leaf (plate-like body) precoated with diatomaceous earth powder or an element as a filter material. (3) A cartridge system using a cartridge incorporating a hollow fiber wound fiber element. Recently, a combined treatment system in which the circulating water passed through the filtration tanks of the above-mentioned methods (1) to (3) is further passed through an activation tank to further reduce pollution, elute minerals, pH
Various researches have been made on filtration devices aiming at adjustment, activation of water quality, and the like. In this case, as filter media used in the activation tank, quartz porphyry called barley rock, natural / artificial zeolite, activated carbon, shirasu balloon, fossil coral, porous ceramics and the like are known.

In any of the above-mentioned systems, a sterilizer is added as required, and the circulating liquid after passing through a filtration tank (an activation tank in the case of the above-mentioned combined treatment system) is used. Sterilization is performed by passing through the sterilizer. As a sterilizer, a sterilizer using sodium hypochlorite has been widely used, but recently, a device using ultraviolet light or ozone has been developed.

[0006] Recently, a filtration device has been proposed in which a filtration tank is provided in multiple stages and circulating water after final filtration is sterilized by a predetermined sterilization device. FIG.
This is a conventional example of such a filtration device. The filter shown in FIG. 8 is used for treating hot water in a bathtub.
The hot water in the bathtub 1 was sent to the first filtration tank 3 and the second filtration tank 5 by the pump 2 in order, and passed through the second filtration tank 5. The hot water is sterilized by an ultraviolet germicidal lamp 8 equipped as a sterilizer and then returned to the bathtub 1. In this case, the first filtration tank 3 includes:
Glass beads 4 having a diameter of about 200 μm are loaded as a filter material, and a second filtration tank 5 is loaded with porous ceramics as a filter material, and an air pump for keeping the inside of the tank in an aerobic atmosphere. 7 is equipped.

[0007]

In the above various conventional filtration apparatuses, a sand filtration method shown in the above (1) or a sterilization apparatus for performing sterilization by injecting sodium hypochlorite is added thereto. The most popular type is the most popular. This is because the filter structure is simple and the filter material is relatively inexpensive, and the filter material contaminated by use can be easily purified by back washing or the like, and the device cost and running cost can be reduced. This is because there is an advantage that maintenance is easy. However, such an apparatus configuration is effective only for removing turbid matter of about 50 μm or more, and has no effect on the removal of soluble organic pollutants, ammonia nitrogen, and fungi.

By replacing the filtration tank used with the diatomaceous earth filtration method shown in (2) or the cartridge method shown in (3), it is possible to remove turbid matter of about 5 μm. In this case, however, the problem remains that it is not effective in removing soluble organic pollutants, ammonia nitrogen, and fungi. In addition, maintenance problems such as an increase in the cost of the filter material and the necessity of replacing the filter material arise.

Further, if a combined treatment system is further added with an activation tank using the above-mentioned quartz porphyry or the like as a filter material, removal of soluble organic pollutants, ammonia nitrogen and fungi can be effectively performed. Although the capacity is excellent, the number of processing tanks increases, which complicates the apparatus configuration, causing problems such as an increase in apparatus cost, an increase in apparatus size, and an increase in running cost.

[0010] In the case of a device equipped with a plurality of filtration tanks, such as the structure disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-15897, similarly, the configuration of the device becomes complicated, the cost of the device increases, and the size of the device increases. Problems, such as increase in running cost and running cost. Therefore, instead of the usual quartz sand, an active stone such as quartz porphyry having the same particle size as the quartz sand is used as a filtering material in the filtration tank used in the sand filtration method of the above (1). It is considered to be loaded. This way,
This is because both the effect of sand filtration and the effect of activated stone can be obtained by the treatment with one filtration tank, and the simplification of the device configuration and the improvement of the filtration function can be achieved at the same time. .

However, activated stones such as quartz porphyry generally have a lower mechanical strength than silica sand and the like, and when backwashing or the like is performed, the particles of the filter material are broken, causing problems such as clogging. There is no practical. Further, conventionally, in the case of an extremely fine filtration material having a particle size of, for example, 2 mm or less, it is very difficult to collect from natural stone, and even if it can be collected, there is a problem in its mechanical strength. Was not practical. Furthermore, at present, such a filter medium having a small particle size cannot be manufactured with good productivity by firing or the like.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a 50 μm filter using a single filtration tank for sand filtration.
m can be used to filter turbid substances, soluble organic pollutants, ammonia ions, fungi, etc., which reduces the equipment cost and running cost of the filtration equipment, and at the same time makes the equipment smaller and easier to maintain. It is an object of the present invention to provide a fine-grained ceramic filter material capable of achieving the filtration, a method for producing the same, and a filtration device using the filter material.

[0013]

SUMMARY OF THE INVENTION The object of the present invention is to provide a water supply system comprising:
Chris moisture-treated to a content of 25-35wt%
About 0.8 mm in diameter of semi-milled material mainly composed of toberite
Extruding into a cylindrical shape having a maximum length of 20 mm;
Extruded products formed in the extrusion process are used for rolling molding
Forming a more nearly spherical shape, and
Baking the shaped extruded article;
Fine particles made of porous ceramics with a maximum particle size of 2 mm or less
Can be achieved by a method of manufacturing a granular ceramic filter material.
You can do it. Further, the above object of the present invention is as described above.
Manufactured by the method for manufacturing fine-grained ceramic filter media
That can be achieved by a fine-grained ceramic filter material characterized by
It can be.

It is another object of the present invention to provide a liquid tank storing a liquid to be filtered and the above-mentioned fine ceramic filter medium as a filter medium, and change the flow direction of the liquid passing through the filter medium. And a circulating pump for circulating the liquid in the liquid tank between the liquid tank and the filtration tank. Can be achieved by a filtration device characterized by
It can be.

[0015]

According to the above-mentioned structure of the present invention, the fine-grained ceramic filter material has a substantially spherical shape with a particle size equivalent to that of silica sand, and is porous. By loading and using the filter material in a filtration tank as described above, it is possible to obtain both a filtration effect as a silica sand sand and a filtration effect by porous adsorption or the like. As well as the combined treatment method in which an activation tank loaded with is added, an excellent filtration effect is also obtained for filtration of turbid substances or soluble organic pollutants of 50 μm or less, ammonium ions, fungi, etc. Can be.

In addition, the processing tank can be replaced with only a single filtration tank for sand filtration, and the mechanical strength of the fine-grained ceramic filter material is improved by the firing step so that it is similar to silica sand. Since the strength can be ensured and the filter material particles can be prevented from being broken at the time of backwashing, it is possible to adopt a simple filter material purification method such as backwashing. Therefore, it is possible to reduce the size and ease of maintenance of the apparatus while reducing the apparatus cost and running cost of the filtration apparatus.

Further, various physical properties such as the maximum particle size, the attrition rate, the hydrochloric acid solubility, the effective diameter, and the uniformity coefficient are standardized and required for the filter medium according to the use or the like. But,
According to a production method in which a semi-milled substance of cristobalite is subjected to rolling molding after extrusion molding, for example, the fine granules having a substantial maximum particle size of 2 mm or less satisfying physical properties required for filter sand by the Japan Water Works Association. Ceramic filter media can be easily obtained with good productivity.

[0018]

1 and 2 show an embodiment of a method for producing a fine-grained ceramic filter material according to the present invention, and FIG. 3 shows a structure of a filtration device using the fine-grained ceramic filter material. Things. The fine-grained ceramic filter material according to the present invention is a porous ceramic whose main material is made of natural cristobalite (hereinafter referred to as cristobalite), and which has a substantially maximum particle size of 2 mm or less and is substantially spherically fired. .

This fine-grained ceramic filter material is manufactured by the process shown in FIG. First, bentonite is added as a binder to cristobalite powder, and pure water is sprayed on the binder to adjust the humidity, and the mixture is kneaded with a forced stirring mixer such as a Henschel mixer or a paddle mixer to produce a semi-milled substance (step). 101). In this case, the cristobalite powder used has been crushed to a diameter of 150 μm or less, preferably to a diameter of about 20 μm. The blending ratio of bentonite added as a binder to cristobalite was 5 wt%.
It is possible to knead the mixture without adding a binder and only by adjusting the humidity with pure water.

For controlling the humidity of the mixture of the cristobalite powder and the binder, it is preferable to use a spray atomizer for spraying water from a nozzle into a kneading vessel of a forced stirring mixer containing the mixture. Next, when the mixture is kneaded to a predetermined viscosity, the semi-kneaded material is extruded by a disk pelletizer into granules of a predetermined size (step 10).
2).

In order to obtain a fine-grained ceramic filter material having a maximum particle size of 2 mm or less, step 10 is performed so that the extruded product becomes a thin columnar shape having a diameter of 0.8 mm and a maximum length of about 20 mm.
Humidity control treatment in 1 (water content is 25 to 35 wt%)
Is controlled to form a smooth surface. Then, the extruded grains are rolled on a loading container and shaped into a predetermined shape.
By dividing the columnar material having a small thickness into a desired length, the grains formed in Step 102 are formed into substantially spherical grains (Step 103).

At the time of rolling molding, as shown in FIG. 2, the humidity is adjusted by using a two-fluid type spray atomizer that sprays water from two or more nozzles 11 into a container 10. The spherical particles shaped in step 103 are baked at 800 to 1000 ° C. for 30 minutes to 1 hour using a rotary rotary kiln to obtain solid particles having predetermined strength (step 10).
4) End the manufacturing process.

The filtering device shown in FIG. 3 is loaded with a liquid tank 14 storing a liquid to be filtered and a fine ceramic filter material 15 according to the present invention as a filter material, and passes the filter material 15 through. A filtration tank 16 capable of filtering the inflowing liquid or washing the filter medium 15 by changing the flow direction of the liquid.
And a circulating pump 17 for circulating the liquid in the liquid tank 14 between the liquid tank 14 and the filtration tank 16.

The liquid tank 14 is, for example, a bathtub or a pool, and a feed pipe 18 for feeding the liquid in the liquid tank 14 to the filtration tank 16 has a collecting pipe for removing hair and the like. Hair vessel 19, chemical solution dissolving tank 2 for adding filtration aid and pH adjuster
0, and a sterilizer 22 for performing a sterilization treatment such as chlorine sterilization on the filtered liquid is provided on a return line 21 for returning the liquid having passed through the filtration tank 16 to the liquid tank 14. It has become.

The filtration tank 16 is a filtration tank for sand filtration.
On the gravel layer 24 spread on the bottom side, a filtration layer 25 made of the fine-grained ceramic filter material 15 according to the present invention is located. In the gravel layer 24, a water collecting device 27 communicating with the return line 21 is disposed. Above the filtration layer 25, an opening is formed toward the exhaust layer 28 thereon, and the feed line 18 is formed. Is disposed.

With the above construction, the liquid in the liquid tank 14 is usually supplied from the feed pipe 18 through the sprinkler 29 to the filtration tank 16.
After being sprinkled into the filter and filtered by passing through a filter layer 25, a water collecting device 27 and a return pipe 21 are obtained from the gravel layer 24 and returned to the liquid tank 14. When the contamination of the fine ceramics filter material 15 has progressed, the flow direction of the liquid in the feed line 18 and the return line 21 is changed, and the liquid flows in the filtration tank 16 in the opposite direction to the normal direction. The back-cleaning purifies the fine-grained ceramic filter material 15 and makes it reusable.

The inventor of the present application has determined the mechanical strength and other physical properties of the fine-grained ceramic filter material 15 of the present invention actually manufactured by the above-described manufacturing method, and the filtering performance when used in the above-described filtering apparatus. Examined. The results will be described below. First, a sample A and a sample B were manufactured as the fine-grained ceramic filter material 15 for the physical property test. Then, for each sample, the particle size distribution and physical properties were measured. As the particle size distribution, the effective diameter (unit: mm) and the uniformity coefficient are also obtained. As the physical properties, the bulk density and the crushing strength (unit: kgf / cm)
2) The abrasion rate (unit;%) and the hydrochloric acid solubility (unit;%) were measured.

The results of each measurement are as shown in Table 1 below.

[0029]

[Table 1]

In Table 1, the effective diameter is the size of a sieve through which 10% of the total weight of the sample passes.
The equality coefficient is defined as the value of 4% when 60% of the total weight of the sample passes.
0% is the ratio between the size of the remaining sieve and the effective diameter. These are obtained by plotting the measurement results of the particle size distribution measurement for measuring the weight passage ratio with respect to the size of the sieve for each sample on a log-probability paper, and calculating the particle size addition curve in FIG. A, and the broken line is for sample B).

As shown in Table 1, the fine-grained ceramics filter material 15 manufactured by the above-described manufacturing method is about 97%.
% Of the particles become 2 mm or less in particle size, and the substantially maximum particle size is 2 mm.
In addition, the effective diameter is 0.5 mm or less, the uniformity coefficient is 1.52 or less, the attrition rate is 0.34% or less, and the hydrochloric acid solubility is 3.2% or less. It is a value that satisfies the physical property standards required for filter sand by the Federation. Also, among the fine-grained ceramic filter media manufactured by the above-described manufacturing method of the present invention, those having a particle size of 0.59 to 1.19 mm are added to the specimen,
A circulating water purification performance test was performed. This test is for confirming the purification ability as an activated fossil. An ammonia ion adsorption characteristic test and a purification verification test using a running pool water as a sample were performed.

The ammonia ion adsorption test is a laboratory test for the temporal change of NH ₄ ⁺ ions from a standard solution that is circulating water. Specifically, an ammonium chloride standard solution (NH ₄ ⁺ ; 11.4 mg) is used. / Ml) 300 ml was poured into a triangular flask, and a sample containing a fine ceramic filter material having a predetermined particle size (0.59 to 1.19 mm) of the present invention and a sample not containing the same were placed in the flask. create. Each sample was sealed by sealing the opening of the flask with a rubber stopper, and slowly reciprocated on an auto shaker to stir (80).
(Reciprocation / min), and the residual ammonia ions were measured at regular intervals. The measurement results were as shown in Table 2 and FIG.

[0033]

[Table 2]

The samples prepared were five samples from No. 1 to No. 5, No. 1 was blank water to which the fine ceramics filter material of the present invention was not added at all, and No. 2 was fine water of the present invention. No. 3 to which 15 g of granular ceramic filter material was added
No. 4 added 45 g of the fine ceramic filter material of the present invention, and No. 4 added 30 g of the fine ceramic filter material of the present invention.
No. 5, to which 90 g of the fine-grained ceramic filter material of the present invention was added.

The tendency is that as the amount of the fine-grained ceramic filter material of the present invention increases, the residual amount of ammonia ions decreases, and the fine-grained ceramic filter material of the present invention is effective in removing ammonia ions. It was confirmed that.
It is considered that the removal of ammonia ions by the fine-grained ceramic filter material of the present invention is caused by the adsorption of the silicic acid, which is the main component of cristobalite, by the crystal structure (SiO ₄ ^4- ; silanol group). In other words, it is considered that this is because the crystal outer surface is negatively charged by the silanol group, so that the positive ion, NH ₄ ^+, is attracted to keep the electrical neutrality.

The fine-grained ceramic filter medium of the present invention used was sufficiently fresh, and was subjected to biological nitrification (NH) by nitrifying bacteria (Nitrosomonas, Nitrobacta).
₄ ⁺ → NO ₂ ^- → It is not considered that NH ₄ ⁺ is reduced by NO ₃ ^2- ). On the other hand, in the purification verification test using the pool water in operation, a sample obtained by collecting the pool water in operation was used as a sample, and the fine ceramic filter material of the present invention having a particle size of 0.59 to 1.19 mm was added thereto. After addition, the organic pollutants (consumption of potassium permanganate) due to vibration stirring, the reduction of NH ₄ —N with time, the presence or absence of E. coli, etc. were measured.

The pool water is collected at 6:30 in the evening when the pool has the highest load. Immediately after the collection, the fine ceramic filter material 15 of the present invention is added to the pool water in a plastic container on a vibrating table. Was prepared, and the mixture was stirred by reciprocating 95 times per minute. The room temperature at that time is 5 ° C
At every certain time, potassium permanganate consumption and reduction of NH ₄ —N with time, presence or absence of Escherichia coli, and the like were measured.

The samples measured were No. 1 to No. 1.
No. 1 is a blank water as it is pooled water, No. 2 is a filter to which 5 g of the fine ceramic filter material of the present invention is added, and No. 3 is a fine water filter material of the present invention. No. 4 added 5 g of quartz porphyry instead of the fine-grained ceramic filter material of the present invention, and No. 4 added 5 g of silica sand instead of the fine-grained ceramic filter material of the present invention. . The quartz porphyry added to the specimen of No. 4 was crushed and sieved to the same particle size as the fine-grained ceramic filter material of the present invention (the particle size was 0.59-1.
No. 4 silica sand (particle size of 0.42 to 0.84) was used for the sample No. 5
mm).

The changes over time in the consumption of potassium permanganate are shown in Table 3 and FIG. 6, the changes over time in NH 4 —N are shown in Tables 4 and 7, and the presence or absence of E. coli is shown in Table 5. It was as shown.

[0040]

[Table 3]

[0041]

[Table 4]

[0042]

[Table 5]

As shown in Table 3 and FIG. 6, the fine ceramic filter material of the present invention shows that after 12 hours, regardless of the amount of addition, It has almost the same effect of reducing organic pollution. The sample to which quartz porphyry was added had a reduction in organic pollution after about 12 hours of about 12%, and the sample to which silica sand had been added was only about 14%. When the fine ceramic filter material of the present invention is added, a reduction of about 21% is observed, and the effect of reducing organic pollution is as follows.
It was confirmed that the fine-grained ceramic filter material of the present invention exhibited better filtration performance than quartz porphyry and quartz sand.

Incidentally, in the case of the sample of No. 4, after one hour, the concentration is once reduced to 10.3 mg / liter.
Then, to the extent that the sample pool water turns light brown,
Turbidity appeared and continued until the end of the test. This turbid component is ferrous oxide, and it is considered that potassium permanganate consumption increased conversely due to this reducing substance.
In the samples Nos. 2 and 3 and the sample No. 5, the above-mentioned turbidity does not occur.

Further, as shown in Table 4 and FIG.
The time-dependent change of _4- N was also about 42% and 4% in the samples of Nos. 2 and 3, respectively, compared to the concentration of NH ₄ -N in the blank water.
A reduction rate of 7% was obtained, and it was confirmed that filtration performance superior to quartz porphyry and quartz sand was obtained. The presence or absence of Escherichia coli was determined by stirring each sample for 1 hour and 4 hours, collecting 1 ml of each sample, immersing the sample in a commercially available bacterial test paper, and culturing at 36 ° C for 20 hours. is there. As shown in Table 5, the fine-grained ceramic filter material of the present invention exhibited a good removal effect.

As described above, according to the fine-grained ceramics filtering material of one embodiment, the fine-grained ceramics filtering material is substantially spherical and has the same particle size as the quartz sand, and is porous. In place of the above, a filter tank for sand filtration is charged and used as a filter material, whereby both a filtration effect as a silica sand sand and a filtration effect by porous adsorption or the like can be obtained. As in the case of the combined treatment method in which an activation tank loaded with activated stones such as quartz porphyry is added, 50%
An excellent filtration effect can be obtained also for filtration of turbid substances of less than μm, soluble organic pollutants, ammonia ions and fungi.

In addition, the treatment tank can be replaced with only a single filtration tank for sand filtration, and the mechanical strength of the fine-grained ceramic filter material is improved by the calcination step, and is similar to that of silica sand. Since the strength can be ensured and the filter material particles can be prevented from being broken at the time of backwashing, it is possible to adopt a simple filter material purification method such as backwashing. Therefore, it is possible to reduce the size and ease of maintenance of the apparatus while reducing the apparatus cost and running cost of the filtration apparatus.

Further, various physical properties such as the maximum particle size, the attrition rate, the hydrochloric acid solubility, the effective diameter, and the uniformity coefficient are standardized and required for the filter medium according to the application. But,
According to a production method in which a semi-milled material of cristobalite is subjected to rolling molding after extrusion molding, for example, the fine-grained ceramics having a substantial maximum particle size of 2 mm or less satisfying physical properties required for filter sand by the Japan Water Works Association. Filter material can be easily obtained.

[0049]

According to the fine-grained ceramic filter material of the present invention, the fine-grained ceramic filter material is substantially spherical and has the same particle size as silica sand, and is porous. By using the filter material as a filter material in a filtration tank for sand filtration, it is possible to obtain both a filtration effect as a silica sand sand and a filtration effect by porous adsorption or the like. As in the case of the combined treatment method in which an activation tank loaded with activated rock such as rock is added, the filtration is excellent in filtering turbid substances and soluble organic pollutants of 50 μm or less, ammonia ions and fungi. Overeffect can be raised.

In addition, the treatment tank can be replaced with only a single filtration tank for sand filtration, and the mechanical strength of the fine-grained ceramics filter material is improved by the firing step so that it is similar to silica sand. Since the strength can be ensured and the filter material particles can be prevented from being broken at the time of backwashing, it is possible to adopt a simple filter material purification method such as backwashing. Therefore, it is possible to reduce the size and ease of maintenance of the apparatus while reducing the apparatus cost and running cost of the filtration apparatus.

Further, various physical properties such as the maximum particle size, the attrition rate, the hydrochloric acid solubility, the effective diameter, and the uniformity coefficient are standardized and required for the filter medium according to the application. But,
According to a production method in which a semi-milled material of cristobalite is extruded and then roll-molded, for example, the fine-grained ceramic filter material having a maximum particle size of 2 mm or less that satisfies physical properties required for filtered sand by the Japan Water Works Association. Can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of one embodiment of a method for producing a fine-grained ceramic filter material according to the present invention.

FIG. 2 is an explanatory view at the time of kneading in the method for producing a fine-grained ceramic filter material according to the present invention.

FIG. 3 is a schematic structural explanatory view of a filtration device using a fine-grained ceramic filter material according to the present invention. Equipment

FIG. 4 is a graph showing a grain size accumulation curve of each sample.

FIG. 5 is an explanatory diagram of a change over time of ammonia ions by a fine-grained ceramic filter material according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram of the change over time of the consumption of potassium permanganate by the fine-grained ceramic filter material of one embodiment of the present invention.

FIG. 7 is an explanatory diagram of the change over time of NH ₄ —N by the fine-grained ceramic filter material of one example of the present invention.

FIG. 8 is a diagram illustrating the configuration of a conventional filtration device.

[Explanation of symbols]

 14 Liquid tank 15 Fine-grained ceramic filter material 16 Filtration tank 17 Circulation pump 18 Feed line

Claims (3)

(57) [Claims] (1) Humidity control so that the water content is 25 to 35 wt%.
Semi-compounded material mainly composed of treated cristobalite
Extruded into a cylinder with a diameter of about 0.8mm and a maximum length of 20mm
And the extrusion molding formed by the extrusion molding step.
Shaping the product into a substantially spherical shape by rolling molding;
Baking the extruded product shaped by the forming process.
Porous ceramic having a maximum particle size of 2 mm or less
A method for producing a fine-grained ceramic filter material made of powder. 2. The fine-grained ceramic according to claim 1,
Fine granules produced by a method for producing filter media
Ceramic filter media. 3. A liquid tank in which a liquid to be filtered is stored, and the fine ceramic filter material of claim 2 is loaded as a filter material, and the liquid is allowed to flow by changing the flow direction of the liquid passing through the filter material. A filtration tank capable of filtering the filtered liquid or washing the filter material, and a circulation pump for circulating the liquid in the liquid tank between the liquid tank and the filtration tank. Filtration equipment.