JPH08290191A - Catalytic filter medium in catalytic oxidation type water purifying device - Google Patents

Abstract

PURPOSE: To provide a catalytic filter medium in a catalytic oxidation type water purifying device, which is excellent in biological and organism affinities, low in cost, having durability and excellent in purifying action. CONSTITUTION: The catalytic filter medium is made of a biological film carrier 10 formed by binding many carbon fiber filaments 12 of the biological film carrier into a prescribed form so that the each filament 12 moves in water such as sea weed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact filter medium which is a biofilm carrier used in a method for purifying water such as water and sewage, rivers and lakes using a biofilm (hereinafter referred to as catalytic oxidation method). Regarding

[0002]

2. Description of the Related Art BOD, COD and fine organic matter S in wastewater are produced by contacting wastewater with a biofilm formed of bacteria, protozoa and metazoans formed on a biofilm carrier.
A catalytic oxidation method for removing S and turbidity components is known.
FIG. 7 shows an example of a river water purification apparatus using the catalytic oxidation method.

The water of the river 1 is sent to a sand basin 3 after removing suspended matters by a screen 2, where pebbles and sand are removed, and then sent to a contact oxidation water channel 4 by a pump P. The contact oxidation channel 4 has a structure in which a contact filter medium composed of a number of corrugated plates 5 made of plastic, which is a biofilm carrier, is laminated in parallel with a predetermined gap in a meandering channel. When flowing through the gap between the corrugated plates 5 and 5, the biological film formed on the surface of the corrugated plate 5 comes into contact with and is purified. The water purified by passing through the contact oxidation water channel 4 is discharged from the drainage channel 6 to the river 1.

[0004]

However, as a biofilm carrier which constitutes the above-mentioned conventional contact filter medium, a synthetic resin which is lightweight and easy to process is widely used. It has low biocompatibility, and if left in a large amount, it becomes industrial waste, which may cause pollution problems, and is not preferable in terms of the global environment. Further, the conventional biofilm carrier is corrugated to increase the contact surface area, but the surface area of the corrugated plate (area where the biofilm is adhered and formed) is inevitably limited.

Therefore, the inventor has paid attention to a carbon material which is a hardly decomposable substance existing in nature. That is, first of all, the carbon material is very excellent in biocompatibility and biocompatibility. Second, since the carbonaceous material has a positive charge, it is considered to be a very easy place to settle for a microorganism having a negative charge. In addition, various carbon materials include various graphite materials, glassy carbon materials, carbon black, activated carbon, charcoal, coke and the like. When using a carbon material, it is formed into a shape suitable for the intended use. And carbon fiber is one of the carbon materials. Carbon fiber is widely used in the aerospace industry, sports equipment, etc. because it has excellent specific strength, specific elastic modulus and chemical resistance. Thirdly, carbon fiber can be molded by compounding it with resin or concrete, or can be molded into any shape due to the flexibility of carbon fiber itself, and also in terms of durability. Are better. Furthermore, microorganisms (biofilm) on the biofilm carrier formed by carbon fiber
When the fixing degree of was investigated by an experiment, a very good result was obtained, and based on this result, the inventor proposed the present invention.

The present invention has been made on the basis of the above-mentioned problems of the prior art and the above-mentioned consideration by the inventor, and an object thereof is to have excellent biocompatibility and biocompatibility, to be inexpensive and durable. Another object of the present invention is to provide a contact filter medium in a catalytic oxidation type water purification device which is excellent in purification action.

[0007]

In order to achieve the above-mentioned object, in the contact filter medium in the catalytic oxidation type water purifying apparatus according to claim 1, the biofilm carrier is made of carbon fiber. The carbon fiber that constitutes the biofilm carrier has high biocompatibility and biocompatibility, and does not go back to the natural environment. In addition, carbon fibers are easily charged with a positive charge, and microorganisms that are easily charged with a negative charge are easily attached thereto. Therefore, the degree of fixation of the biofilm on the carbon fiber is high. In claim 2,
The contact filter medium in the catalytic oxidation type water purification device according to claim 1, wherein the biofilm carrier is bound, compressed, or knitted with a large number of flexible and flexible carbon fiber filaments.
It is woven or constructed by a molded body molded into a predetermined shape that can be swung in water, and flexible and flexible carbon fiber filaments are bound, compressed, knitted or woven. The molded body molded into a predetermined shape by oscillating like underwater underwater like natural seaweed or algae supplies oxygen, which is indispensable for promoting the activity of the microorganisms, to the microorganisms forming the biofilm. In claim 3,
The contact filter medium in the catalytic oxidation type water purifying apparatus according to claim 2, wherein a molded body composed of carbon fiber filaments is bound at both ends into a strand shape, a net shape, a braided shape, a tethered strand shape, and a branched strand shape. , Lantern-type strands, broom-type strands, Akita's kanto-type strands, felt-types, etc. are formed into a predetermined shape that increases the exposed surface area of carbon fiber filaments in water. Then, the carbon fiber filaments that make up the molded body each oscillate, and the exposed surface area of the carbon fiber filaments (area where the biofilm can be fixed)
Grows larger.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a view showing a contact filter medium which is a first embodiment of the present invention. Reference numeral 10 is a biofilm carrier composed of carbon fiber strands in which both ends are bound by bundling a large number (tens of thousands) of carbon fiber filaments 12 having a diameter of 7 μm to 15 μm, for example. One end of the biofilm carrier 10 is connected and supported to a cord-like connecting member 14 such as a rope supported by an anchor bolt 13 fixed to the bottom of the contact oxidation water channel 4 as shown in FIG. Is connected to and supported by a pipe 17 which is connected to the float 15 via a cord-like connecting member 16 such as a rope.
The contact filter medium has a structure in which 0s are arranged at a predetermined interval.

The biofilm carrier 10 is apparently one bundle in the air due to the viscosity of the binding agent applied to the surface of each filament 12, but in the sea or water,
Each filament 12 is a spindle type which is separated from each other,
It can swing like seaweed according to the movement of the tide. Therefore, in water, the biofilm carrier 10 (carbon fiber filament 1
Since the contact surface area with the microorganism of 2) increases, the microorganism easily attaches to the biofilm carrier 10 (the carbon fiber filaments 12 constituting the biofilm carrier 10), and the biofilm fixing rate and the fixing amount are large.

Further, as the biofilm carrier, in addition to the strand-shaped molded body in which both ends are bound as shown in FIG.
Various forms as shown in (a) to (g) are possible. FIG. 2A shows a braided strand formed body in which the carbon fiber filaments 12 are knitted into a braided shape, and the filaments 12 are bulged in a tuft shape at predetermined intervals in the longitudinal direction.

FIG. 2B shows a carbon fiber filament 12
This is a dendritic strand formed body in which multiple strands are branched from the strand base portion 12a. Figure 2
(C) is a broom type strand molded body in which a plurality of carbon fiber strands 12b are connected and integrated with a strand base portion 12a of the carbon fiber filament 12.

FIG. 2D shows a carbon fiber filament 12
A plurality of arc-shaped strands 12c are formed in the middle of the strand main portion 12a of the above, which is a lantern-shaped strand formed body. FIG. 2 (e) is an Akita kanto type strand formed product in which the carbon fiber strands 12 b are integrally connected to the strand base portions 12 a of the carbon fiber filaments 12 at predetermined longitudinal intervals.

In FIG. 2 (f), string-like connecting members 22 such as ropes are arranged at a predetermined interval, and the carbon fiber strands 12b are twisted to be connected and integrated so that the strands become ring-shaped between the ropes. It was done. Reference numeral 24 indicates a connecting portion.
FIG. 2 (g) is a net-shaped strand formed body in which the carbon fiber strands 12b are knitted in a hexagonal shape.

Other examples of the carbon fiber filament molded body include those obtained by compression-molding a strand into a felt shape, winding the strand into a coil to form a twisted thread, plain weave or satin weave. Textile shaped articles woven in various ways such as In addition, as the biofilm carrier, the carbon fiber filaments 12 that are the biofilm carrier constituents can be scattered and swung in the sea or water, and the contact surface area of the carbon fiber filaments 12 that is the biofilm carrier with the microorganism becomes large. The molded product of (1) is not limited to the molded product of the above-mentioned form.

FIG. 3 shows a braid-like carbon fiber strand (hereinafter referred to as a braid) as a test material for a biofilm carrier, and a cord-like carbon fiber strand having a form as shown in FIG. 1 (hereinafter referred to as a swing linear strand). ), Felt-like carbon fiber (hereinafter referred to as “felt”), nylon string and polyethylene tape were hung in water tanks containing artificial sewage, respectively, and the results of examining the change characteristics of COD (chemical oxygen demand) in artificial sewage FIG.

[0016] Braid, which is a test material, swing straight type strand,
The felt, nylon string and polyethylene tape all have the same weight (18.9 g), and as shown in FIG.
Both upper and lower ends were fixed so that they could be rocked in water. The artificial sewage to be placed in a transparent water tank is first prepared by dissolving reagents (glucose, ammonium sulfate, dipotassium phosphate, sodium chloride, magnesium sulfate, potassium chloride, etc.) in 1 liter of water to make artificial sewage equivalent to BOD 500 ppm. 10 times the volume of pond water is added to the total volume of about 80
Water made up to 1 liter was used. Then, each sample material (braided braid, oscillating linear strand, felt, nylon string and polyethylene tape) was hung in a water tank, and aeration was performed for about one week in the sun to carry out an experiment to fix microorganisms to these sample materials. went. Then, the change in COD in the artificial sewage was measured by the potassium permanganate titration method.

FIG. 3 (a) shows the result of the first experiment (after 3 days), and FIG. 3 (b) shows the result of the second experiment (after 1 day). First experiment (Fig. 3 (a))
According to the results, there is not much difference in COD value in any of the test materials, but according to the second experiment (Fig. 3 (b)), a large difference in COD value is found due to the difference in the test materials. .
That is, when a carbon fiber material having a large surface area (felt) is used, the COD value is most significantly reduced.

FIG. 4 shows that the PAN-based carbon fiber strands (12K oscillating linear strands) which are the test materials and the tape-shaped polyethylene which is the comparative material were aerated in the activated sludge, respectively, and the biofilms were applied to these test materials. Fig. 4 is a table that compares the degree of fixation of
FIG. 4A shows the amount of sludge when left to stand for 1 day and then settled for 30 minutes, FIG. 4B shows the change with time of COD, and FIG. 4C shows the change of the weight of the test material.

The oscillating linear type carbon fiber strand molded body comprises five carbon fiber strands (12K) (12K × 5).
= 60K), and a molded product as shown in FIG. 1 was used in which the upper end and the lower end were bound and integrated. The length of the carbon fiber strand was 30 cm, and the total weight of the carbon fiber strand formed by bundling five carbon fibers was about 0.3 g. Five sets of this carbon fiber strand formed body were prepared, and the weight of each set was measured.

About 500 ml of activated sludge was added to each of the two 5-liter air collecting bottles, and the total volume was made up to about 3 liters with water. The contents of the air collection bottle were well stirred and allowed to spontaneously settle for 30 minutes, and the amount of sludge deposited was measured (settling sludge amount after 0 minutes). Next, 5 sets of carbon fiber strand molded bodies whose weights were measured were suspended in an air collection bottle containing activated sludge and aerated. Further, about 5% of the total volume of artificial sewage whose BOD was adjusted to 1000 ppm was added as a nutrient for microorganisms. Collect the liquid in the air collection bottle that is being stirred by aeration, and
After the sludge was allowed to settle for 0 minutes, the COD of the supernatant was measured by the potassium permanganate titration method. On the other hand, 5 sets of polyethylene tapes (width 5 cm) whose weight was adjusted to the range of 0.3 g to 0.4 g were also treated in the same manner as above, and both were left for 1 day while aerating in the sun.

After standing for 1 day, the amount of sludge deposited was measured by spontaneously sedimenting for 30 minutes. Furthermore, the supernatant was collected and COD was measured. In addition, each sample was taken out and its weight was measured, and the increase in weight was taken as the amount of biofilm fixation, and the degree of biofilm fixation in each sample was examined. In FIG. 4 (a),
In the case of polyethylene tape, no change was observed in the settled sludge amount, whereas in the case of the rocking linear carbon fiber strand molded body, the settled sludge amount was remarkably reduced.
This is because the biofilm has settled on carbon fiber,
It can be said that 849 cm ³ of sludge, that is, microorganisms, has settled on the carbon fiber strands. In addition, according to visual observation, a large spherical mass is attached to the carbon fiber strand molded body, while almost no deposit is seen on the polyethylene tape. From this, it can be said that the degree of biofilm fixation on carbon fiber is significantly higher than that on polyethylene tape.

Further, FIG. 4 (c) shows the change in the total weight of the carbon fiber strand molded product and the polyethylene tape including the deposits, and there was an extremely large difference between the two. That is, in the former case, one day later, 9.
There was a weight gain of 20 g to 31.1 g (average 16.32 g) (weight gain due to deposits). On the other hand, the weight increase in the latter case (weight increase due to deposits) was 0.1 g or less.

Next, a similar experiment was conducted on the influence of the form of the carbon fiber strand molded body on the degree of biofilm fixation.
The carbon fiber strand compact used in the experiment is shown in FIG.
The lantern type shown in Fig. 2 and the broom type shown in Fig. 2 (c),
The Akita Kanto type shown in FIG. 2 (e) was used. The polyethylene tape was weighed in the same weight as the carbon fiber strand molded body, and used as a comparative test material. About 500 ml of activated sludge was added to each of four 5 liter air collecting bottles, and the total volume was made up to about 4 liters with water. The contents of each air collection bottle were well stirred and allowed to spontaneously settle for 30 minutes to measure the amount of sludge deposited (the amount of settled sludge after 0 minutes).

Each of the weight-measured test materials was hung in each air-collecting bottle containing activated sludge, oxygen was sent by aeration, and artificial sewage adjusted to a COD of 1000 ppm was used as a nutrient for microorganisms to a total amount of about 5%. % Was added. The liquid in the aeration bottle which was stirred by aeration was sampled, the sludge was allowed to settle for 30 minutes, and the COD of the supernatant was measured by potassium permanganate titration method. The polyethylene tape was also treated in the same manner as above, and both were left for one day while aerating in the sun.

FIG. 5 (a) shows the amount of settled sludge,
The amount of settled sludge after one day was 742 to 884 cm ³ when the carbon fiber strand was used, which means that 247 to 407 cm ³ of sludge was attached to the carbon fiber strand. On the other hand, in the case of polyethylene tape,
The amount of attached sludge is only 8 cm ³ , which is about 1/30 to 1/50 of that of carbon fiber strands. In addition, in terms of the influence of the form of carbon fiber strands on the amount of adhesion, "Akita's Kanto type" was the most effective (large amount of sludge adhesion).

FIG. 5 (b) shows the results of COD measurement. In any case, the COD value is 7 to 11 p / day.
It was decreased by about pm, and no significant difference was observed due to the difference in the type of sample material and the morphology of carbon fiber strands. FIG. 5C shows the amount of sludge attached to the carbon fiber strands and the polyethylene tape, and a remarkable difference was observed depending on the type and shape of the test material. That is, in the case of the carbon fiber strand, the amount increased by 22 to 38 g, whereas in the case of the polyethylene tape, the increase was only about 9 g, and the amount of the sludge adhered to the carbon fiber strand was 2.7 in the case of the polyethylene tape. Was about 4.2 times. The influence of the morphology of carbon fiber strands on the adhesion amount is
The case of "broom type" was the largest. This result was in agreement with the COD reduction amount shown in FIG. Also in FIG.
It does not contradict the result of the amount of settled sludge in (a).

Next, the influence of the type of carbon fiber and the shape of the strand on the degree of biofilm fixation was examined. Carbon fiber is PAN-based carbon fiber strand (12K, Toray, T-
300, which was obtained by removing the applied sizing agent), and two types of pitch-based carbon fiber twisted yarn (twisted two fibers). If the sizing agent layer is formed on the carbon fiber surface, the adhesion rate of the biofilm to the carbon fibers is poor.If the sizing agent is applied to the carbon fiber strands, remove the sizing agent in advance. It is necessary. In addition, the form of the carbon fiber was the "swinging straight type" shown in FIG. 1 and the "broom type" shown in FIG. 2 (c). In the former case, five carbon fiber strands having a length of 45 cm (weight of about 0.3 g) were bundled and used.
In the latter "broom type", five 12K strands having a length of 30 cm were bundled to have a weight of about 1.6 g. Figure 6 (a)
Shows the change in the amount of settled sludge after one day, but in the case of PAN-based carbon fiber strands, the “rocking linear type” has a larger fixed amount than the “broom type”. Further, FIG. 6B shows CO
The change in the D amount is shown. The PAN system is larger than the pitch system, and the "broom type" is larger than the "oscillating linear type".

FIG. 6C shows the change in weight of the carbon fiber strand after one day. The effect of the PAN system was greater than that of the pitch system (the amount of sludge adhered, that is, the degree of biofilm fixation). Some of the data in the case of the PAN system has a weight increase of only 1.5 g, but this is when the test material is twisted and is outside the data. Also, the amount of sludge attached (the degree of fixation of biofilm) is larger in PAN-based carbon fibers than in pitch-based carbon fibers, but this is not the difference between pitch-based and PAN-based carbon fiber types, but rather PNA. It is considered that the pitch-based carbon fiber is in a twisted yarn state, whereas the twisted yarn state is small, and this twisted yarn state reduces the contact surface area of the carbon fiber and reduces the amount of attached sludge.

From the experimental results shown in FIGS. 3 to 6 described above, it is found that a large amount of microorganisms adhere to the carbon fiber in a shorter time than that of nylon or polyethylene, that is, the carbon fiber has a very high degree of biofilm fixation. I can say. Moreover, it can be said that the more the carbon fiber filaments are scattered and the larger the surface area is, the higher the degree of biofilm fixation is.

In the above-mentioned examples, only PAN-based carbon fibers and pitch-based carbon fibers are mentioned. However, other carbon fibers include phenol-based carbon fibers and cellulose-based carbon fibers, and these also have a predetermined form. The present invention can be applied in the same manner by molding into, and can also be applied to activated carbon fibers having a large number of fine pores formed on the surface.

The contact filter medium in the first embodiment is only one embodiment of the present invention. By using a weight instead of the anchor bolt 13, the biofilm carrier 10 can be always maintained at a constant water depth position. It goes without saying that various structures such as a structure may be considered depending on the specifications of the arrangement of the biofilm carrier 10.

[0032]

As is apparent from the above description, according to the contact filter medium in the catalytic oxidation type water purification device of the first aspect, the biofilm carrier has high biocompatibility and biocompatibility, and is regarded as industrial waste. Consistent with the natural environment because it is composed of carbon fiber that is unlikely to become In addition, since carbon fiber is easily charged with a positive charge, it is very easy to attach to microorganisms that are easily charged with a negative charge. Therefore, the degree of fixation of the biofilm on the biofilm carrier composed of carbon fiber is high, and the water quality It has an excellent purification effect. In addition, since carbon fiber is inexpensive, it is possible to inexpensively provide a water purification device having an excellent water purification effect. In the second aspect, the formed body formed by binding, compressing, knitting, and weaving the flexible and flexible carbon fiber filaments into a predetermined shape shakes under water like natural seaweed or algae. As a result, oxygen is actively supplied to the microorganisms forming the biofilm, so that the degree of fixation of the biofilm is promoted and the purification of water quality is promoted. In claim 3, under water, the carbon fiber filaments forming the molded body each oscillate to increase the exposed surface area of the filaments (area where the biofilm can be fixed), so that the degree of fixation of the biofilm is increased and the water quality is further improved. The purification action of is improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a biofilm carrier that constitutes a contact filter medium that is a first embodiment of the present invention.

FIG. 2 is a schematic diagram of various biofilm carriers constituting the contact filter medium of the present invention.

FIG. 3 is a diagram showing changes in COD in carbon fiber strands, nylon strings, and polyethylene tapes.

Fig. 4 (a) Characteristic diagram of change in amount of settled sludge in carbon fiber strand and polyethylene tape (b) Characteristic diagram of COD change with time in carbon fiber strand and polyethylene tape (c) Weight change characteristic of carbon fiber strand and polyethylene tape Figure

FIG. 5: (a) Characteristic diagram of change in settled sludge amount by form of carbon fiber strands (b) Characteristic diagram of COD change with time of form of carbon fiber strands (c) Characteristic diagram of change by weight of carbon fiber strands by form

FIG. 6 (a) Characteristic diagram of change in settled sludge amount by type of carbon fiber (b) Characteristic diagram of COD change with time of type of carbon fiber (c) Characteristic diagram of weight change by type of carbon fiber

FIG. 7 is an overall configuration diagram of a conventional water purification device by a catalytic oxidation method.

[Explanation of symbols]

 10 Carbon fiber strands that are biofilm carriers 12 Carbon fiber filaments

Claims (3)

[Claims] 1. A contact filter medium in a catalytic oxidation type water purification device, wherein the biofilm carrier is composed of carbon fibers. 2. The biofilm carrier is formed by binding a large number of flexible and flexible carbon fiber filaments, bundling it, compressing it, knitting it, weaving it, and forming it into a predetermined shape that can be swung in water. The contact filter medium in the catalytic oxidation type water purification device according to claim 1, wherein the contact filter medium is formed of a molded body. 3. A molded product composed of the carbon fiber filaments has a strand shape in which both ends are bound together, a net shape, a braided shape, a tethered strand shape, a branched strand shape,
A lantern type strand, a broom type strand, an Akita kanto type strand, a felt type or the like, which is formed into a predetermined shape that increases the exposed surface area of the carbon fiber filament in water. A contact filter medium in the contact oxidation type water purifier according to 2.