JP2000102798A - Treatment of wastewater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for treating wastewater which has a high COD value and is conventionally difficult to treat. SOLUTION: This treatment method is for granulating a raw material consisting of 40-99 pts.wt. of clay, 0-30 pts.wt. of diatomaceous earth, 1-30 pts.wt. of dust collector dust and 0-50 pts.wt. of sewage sludge incineration ash into granules, firing the granules to obtain an inorganic porous carrier having a 20-60% porosity, depositing microorganisms on the carrier and thereafter, bringing wastewater having a >=150 ppm COD value into contact with the resulting carrier containing microorganisms to reduce the COD value in the wastewater.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for treating wastewater. More specifically, the present invention relates to a method for treating wastewater having a COD (Chemical Oxygen Demand) component, which was conventionally difficult to treat.

[0002]

2. Description of the Related Art Wastewater such as industrial wastewater and domestic wastewater contains a relatively large amount of organic substances such as nitrogen compounds, phosphorus compounds and oxidizable substances. Since these organic substances cause eutrophication of river water and seawater, it is desired to remove the organic substances and discharge them to rivers and the like. Activated carbon adsorption, ozone oxidation, biological treatment and the like are known as existing methods for removing organic matter from wastewater.

[0003] Among them, the activated carbon adsorption method has a drawback that an oxidizable substance (eg, alcohol) having high hydrophilicity cannot be removed. In addition, the ozone oxidation method
Since the oxidizing power of ozone itself is not large, the oxidizable substance cannot be sufficiently oxidized, so that there is a disadvantage that the substance cannot be sufficiently removed. On the other hand, the biological treatment method has an advantage that various organic substances can be sufficiently removed because microorganisms that degrade the organic substances can be selected according to the kind of the organic substances. Further, since organic matter is removed by using microorganisms, there is an advantage that the influence on the environment is small.

[0004] As biological treatment methods, there are a fixed bed catalytic oxidation method (see, for example, JP-A-6-86993 and JP-A-62-167268) and a fluidized-bed activated sludge method (for example, (See JP-A-54-21052)
Is generally known. The fixed bed method means a method in which microorganism carriers are fixed in a wastewater treatment apparatus, and the fluidized bed method means a method in which microorganism carriers are flowing together with wastewater. Here, the fixed bed system has advantages that the operation stability is high and the maintenance is easy compared to the fluidized bed system.

[0005]

[0003] COD is known as a unit indicating the amount of organic matter contained in wastewater.
Usually, C of wastewater that can be treated by the standard activated sludge method
The OD is about 150 ppm, and when purifying wastewater of COD or more, the wastewater was previously diluted with water until the COD was reached, and then subjected to treatment by a standard activated sludge method. Therefore, when treating wastewater having a high COD, there is a problem that the amount of wastewater to be treated increases by an amount corresponding to dilution with water.

Therefore, there has been a demand for the development of a wastewater treatment method that can treat wastewater having a high COD without directly diluting the wastewater with water.

[0007]

Means for Solving the Problems The inventors of the present invention use an inorganic porous carrier having a specific porosity obtained by granulating and firing a specific raw material,
The present inventors have found that a wastewater having a high COD can be treated as it is without diluting the wastewater with water in advance, and good results can be obtained.

Thus, according to the present invention, clays 40-99
Weight of diatomaceous earth, 1 to 30 parts by weight of dust dust, and 0 to 50 parts by weight of sewage sludge incineration ash. After adhering microorganisms to the porous carrier, C is added to the inorganic porous carrier.
Contacting wastewater with OD of 150 ppm or more
A method for treating wastewater is provided that reduces OD.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION
Porous carrier (hereinafter referred to as “carrier”) is made of clay, silica
Granulate raw materials containing a certain amount of algae soil and dust dust and bake them.
It is obtained by doing. The carrier is SiO_TwoThe main component
And Al_TwoO_Three, Fe_TwoO_Three, Na _TwoO, CaO, M
gO, K_TwoPreferably contains other components such as O
No.

[0010] Here, clay means an aggregate of fine hydrated silicate minerals. Among the clays, a by-product of producing silica sand from raw sand such as mountain sand can be suitably used. Most of this by-product is where raw sand is mined,
At present, it is backfilled as waste. Therefore,
If this clay is used effectively, not only is it economically advantageous, but it is also possible to prevent waste pollution.

As the diatomaceous earth, any of commonly used materials can be used as a raw material for making it porous. As dust collection dust, dust obtained at the time of recycling and recovery of foundry sand can be suitably used. That is, after using a green casting mold (generally composed of sand, bentonite, starch, and coal powder), it is possible to use dust collected when grinding and polishing the surface and regenerating the casting sand. . Dust collected when the organic mold (generally composed of sand and furan resin) is regenerated can also be used. Among these, it is preferable to use dust collected dust containing bentonite.

[0012] The sewage sludge incineration ash means an inorganic component remaining after incinerating excess sludge generated by activated sludge treatment to remove water and organic matters in a sewer final treatment facility. Here, the mixing ratio of clay, diatomaceous earth, dust collected dust and sewage sludge incineration ash constituting the raw materials of the inorganic porous carrier is 40 to 99 parts by weight of clay, 0 to 30 parts by weight of diatomaceous earth, and 1 to 30 parts by weight of dust collected. Parts (preferably 10-20
Parts by weight) and 0 to 50 parts by weight of sewage sludge incineration ash. It is not always necessary to add diatomaceous earth and sewage sludge incineration ash.

These raw materials are first mixed and granulated. The shape of the granulated product is not particularly limited, and may be any of granules, pellets, and spheres. However, spheres are preferable because the surface area can be maximized when used as a carrier. The granulation method is not particularly limited, and a known method can be used. Next, the granulated material can be fired to obtain a carrier. The firing conditions are as follows:
It is preferable that the temperature is 0 ° C. and the time is 30 to 60 minutes.

The above-mentioned materials and manufacturing conditions can be directly used the techniques described in Japanese Patent Application Laid-Open No. 3-215373. The carrier produced under the above-mentioned raw materials and conditions is a porous ceramic body having fine pores and having complicated irregularities on the surface. Moreover, since it is calcined, it is physically and chemically stable for a long period of time. Therefore, when used in the treatment of wastewater, there is an advantage that microorganisms easily adhere to the surface thereof, hardly peel off, and can be used for a long time.

The carrier has a porosity of 20 to 60%. This porosity is a characteristic matter in comparison with the fact that a ceramic porous body obtained from a material other than the above-described raw materials has a porosity of about 70 to 85%. The average particle size of the carrier can be appropriately selected depending on the type of wastewater to be treated, the treatment method, and the like. When a substantially spherical carrier is used in the fixed bed system, the average particle size is usually 1 to 10 m.
m is preferable and 5 to 10 mm is more preferable.

The carrier that can be suitably used in the present invention is, for example, Polarstone (registered trademark) series manufactured by Yamakawa Sangyo Co., Ltd. In the wastewater treatment apparatus in which the inorganic porous carrier is suitably used in the method of the present invention, the configuration of the apparatus can be appropriately changed according to the wastewater treatment method. Specific treatment methods include a method in which the carrier is fixed in the wastewater (fixed bed method) and a method in which the carrier flows in the wastewater (fluid bed method). From another viewpoint, the aerobic treatment method and Although there are anaerobic treatment methods, the method of the present invention is applicable to any of these methods.

The wastewater treatment apparatus has a structure in which a carrier is introduced into a water tank provided with a wastewater inlet and a treated water discharge port. Usually, in order to make the wastewater flow upward, the wastewater is introduced into a lower part. It often has a mouth and a treated water outlet at the top.
And, in the case of the fixed bed method, the carrier is usually under its own weight,
Alternatively, it is fixed in the device by holding means. On the other hand, in the case of the fluidized bed system, it is usual to provide a stirring means such as a stirrer capable of flowing the carrier.

In the case of the aerobic treatment method, the wastewater treatment device has aeration means such as an air pump for circulating air in the wastewater. Furthermore, when a plurality of wastewater treatment devices are used in combination, they may be installed in series and / or in parallel, and the treatment methods of the individual wastewater treatment devices may be different.

Among the above treatment methods, the fixed bed method is preferable in that the manufacturing cost of the apparatus is low and the maintenance is easy. Next, attach microorganisms to the inorganic porous carrier (acclimation)
Let it. The microorganism used in the method of the present invention is not particularly limited, and a microorganism that is contained in wastewater and can assimilate an organic substance and an inorganic substance (component to be treated) to be treated can be used as it is. Furthermore, specific microorganisms may be selected and attached according to the components to be treated contained in the wastewater.
Specific microorganism types include Pseudomonas sp., Achr
Genus omobacter, Alcaligenes, Bacillus, Micrococ
aerobic bacteria such as genus cus, Mycobacterium and Zooglea;
Methanobacterium, Methanosarcina, Methanococcu
Anaerobic bacteria such as s.

As a method for attaching microorganisms to a carrier,
For example, by circulating the wastewater for several days, a method of attaching microorganisms contained in the wastewater, or when attaching a specific type of microorganism, add a seed of the microorganism and circulate the water containing a bionutrient. And a method for attaching microorganisms. Although the initial treatment efficiency decreases, the acclimation may be performed simultaneously with the wastewater treatment.

Next, wastewater having a COD of 150 ppm or more is brought into contact with the carrier to which the microorganisms have adhered. Such wastewater could not be treated as it was in the standard activated sludge method because the COD was too high. On the other hand, according to the method of the present invention, even if the COD of the wastewater is 150 ppm or more (preferably in the range of 150 to 3000 ppm, more preferably in the range of 150 to 1500 ppm, particularly preferably in the range of 200 to 1500 ppm), the COD remains unchanged. Can be processed.

The method of the present invention can be applied to both domestic wastewater (wastewater from kitchens, washrooms, human waste, etc.) and industrial wastewater. In the present invention, the wastewater includes not only water that is directly discarded, but also water that is not discarded but is reused after treatment. According to the method of the present invention, the COD of the wastewater is reduced by 90%, depending on the type of the wastewater and the scale of the wastewater treatment apparatus.
As described above, in some cases, it can be reduced by 95% or more. In addition to COD, the amount of oil and suspended matter in the wastewater can be reduced. Furthermore, if wastewater treatment devices of an aerobic treatment system and an anaerobic treatment system are connected in series, the amounts of nitrogen compounds and phosphorus compounds can be reduced.

If the treatment of the wastewater is carried out for a long period of time, the treatment capacity is reduced due to excessive attachment of microorganisms. In such a case, the treatment apparatus may be backwashed by a known method. . One of the features of the treatment method of the present invention is that the period during which backwashing is required (backwash cycle) is longer than that of the conventional treatment method.

[0024]

The present invention will be described below in more detail with reference to examples. Example 1 In this example, the wastewater treatment apparatus shown in FIG. 1 was used.
In FIG. 1, reference numeral 1 denotes a rigid vinyl chloride wastewater treatment device (JIS
According to 150A, having a height of 1 m; volume 15
Liter), 2 is a wastewater inlet pump, 3 is a wastewater inlet, 4
Denotes a treated water discharge port, 5 denotes a wastewater circulation pump, and 6 denotes an air pump.

As carriers, Polarstone S-10 and S-
5 was used. 1 liter of Polarstone S-10
Was laid on the bottom (reference number 7) of the wastewater treatment apparatus, and 9 liters of Polarstone S-5 (reference number 8) was laid thereon. Polarstone S-10 and S-5 used
Has the following properties.

(Polarstone S-10) ・ Almost spherical ・ Average particle diameter 10 mm ・ Porosity 30-40% ・ Baking 60-80 parts by weight of clay, 5-20 parts by weight of diatomaceous earth and 5-20 parts by weight of dust dust・ Apparent bulk specific gravity 0.9-1.1 ・ Central pore diameter 0.1-0.5 μm

(Polarstone S-5) ・ Almost spherical ・ Average particle size 5 mm ・ Porosity 30-40% ・ Baking 60-80 parts by weight of clay, 5-20 parts by weight of diatomaceous earth and 5-20 parts by weight of dust dust・ Apparent bulk specific gravity 0.9-1.1 ・ Central pore diameter 0.1-0.5 μm

Next, the wastewater treatment device is filled with tap water,
After removing suspended matter adhering to the carrier, tap water was removed. COD 1200pp containing alcohol from a certain pharmaceutical company
m of wastewater is diluted with tap water to a COD of 600 ppm, and this wastewater is inoculated with a seed fungus (genus Pseudomonas, Cybron Chemical Co.)
C1002CG) and a bionutrient (phosjulian made by Mitsui Chemicals, Inc.) were added so as to be 100 ppm and 50 ppm, respectively, to prepare microorganism-adhering water. The microorganism-adhering water was introduced into the wastewater treatment apparatus, the microorganism-adhering water was circulated at 34 liter / min using the wastewater circulation pump 5, and air was introduced into the microorganism-adhering water at 1 liter / min using the air pump 6. . By leaving (conditioning) for 7 days in this state, microorganisms adhered to the carrier, and a microbial membrane was formed.

This wastewater treatment apparatus contains alcohol containing C
1.6 ml of wastewater of a certain pharmaceutical company with an OD of 1200 ppm
At a flow rate of / min, the wastewater was introduced into the wastewater treatment apparatus from the wastewater inlet 3 by the wastewater introduction pump 2 and COD was measured over time. The introduced wastewater is circulated from the bottom to the top in the wastewater treatment apparatus, and the COD is JIS K01
It was measured by the potassium permanganate method according to the 02 factory drainage test method. Table 1 shows the obtained results.

For comparison, non-porous anthracite for a filter and a porous ceramic material for a filter were used in place of polarstone, and wastewater was treated in the same manner as described above. In addition, an anthracite for a filter uses thing with an average particle diameter of 5 mm, and a porous ceramic material for a filter is 4 mesh (4.76 mm) or less and a diameter of 10 mm in a sieve.
The ceramic material except the above was used. Table 1 shows the obtained results.

[0031]

[Table 1]

FIG. 2 plots the results in Table 1 above, with the elapsed days on the horizontal axis and COD on the vertical axis. Table 1 and FIG.
Thus, it can be seen that according to the treatment method of the present invention, the COD of wastewater can be significantly reduced, and its effect does not decrease even in a long-term treatment.

Example 2 In this example, a two-stage wastewater treatment apparatus shown in FIG. 3 was used. In FIG. 3, 1a is a first tank (volume 20 liters), 1b is a second tank (volume 20 liters), 2 is a wastewater introduction pump, 3a and 3b are wastewater inlets, 4a and 4b are treated water outlets, 5a And 5b mean a wastewater circulation pump, and 6a and 6b mean an air pump, respectively.

As the carrier, the same Polarstone S as in Example 1 was used.
-10 and S-5 were used. 5 liters of Polarstone S-10 are spread on the bottoms (reference numerals 7a and 7b) of the first tank 1a and the second tank 1b in FIG.
0 liter Polarstone S-5 (reference numbers 8a and 8)
b) was spread.

Next, the wastewater treatment apparatus is filled with tap water,
After removing suspended matter, tap water was removed. The seed water (genus Pseudomonas, Cybron Chemical Co., DC10) was added to the sample water (COD 600 ppm) for attaching the microorganisms to the carrier.
02CG) and bionutrient (Hosyulian manufactured by Mitsui Chemicals, Inc.)
Was added so as to be 100 ppm and 50 ppm, respectively, to prepare water for microorganism attachment. The microorganism-adhering water is introduced into a wastewater treatment apparatus, and the wastewater circulation pumps 5a and 5b
The water for adhering microorganisms was circulated at 34 liters / minute using, and air was introduced into the water for adhering microorganisms at 3 liters / minute using the air pumps 6a and 6b. By allowing to stand in this state for 7 days, microorganisms adhered to the carrier, and a microbial membrane was formed.

Into the above wastewater treatment apparatus, wastewater of a certain pharmaceutical company containing alcohol is introduced into the wastewater treatment apparatus from the wastewater introduction port 3a by the wastewater introduction pump 2 and COD is made over time in the same manner as in the first embodiment. It was measured. The results obtained are shown in Table 2 together with the amount of wastewater introduced and the COD of the wastewater.

[0037]

[Table 2]

As is clear from Table 2 above, C
OD could be reduced by about 90% or more.

Example 3 In this example, a three-stage wastewater treatment apparatus shown in FIG. 4 was used. In FIG. 4, 1a is a first tank (volume 40 m ³ ),
1b is a second tank (volume 40 m ³ ), 1c is a third tank (volume 4
0m ³ ), 2 is a wastewater introduction pump, 3a to 3c are wastewater introduction ports, 4a to 4c are treated water discharge ports, 5a to 5c are wastewater circulation pumps, and 6a and 6b are air pumps, respectively.

Gravel (average particle size: 15 mm) and the same Polarstone S-5 as in Example 1 were used as carriers. Spread each gravel of 7m ³ on the bottom of the first vessel to third tank of FIG. 4 (1 a to 1 c) (reference number 7 a to 7 c), 20 m ³ thereon
Of Polarstone S-5 (reference numbers 8a to 8c). To this wastewater treatment apparatus, wastewater having a water quality shown in Table 3 below was continuously introduced at 0.42 m ³ / hour. The amount of circulating water in the first tank 1a to the third tank 1c is 1 m ³ / min, the amount of air supplied to the first tank 1a and the second tank 1b is 3 m ³ / min, and air is supplied to the third tank 1c. Did not. The amount of waste liquid introduced from the wastewater inlet was 10 m ³ / day. As a result, aerobic treatment was performed in the first tank 1a and the second tank 1b, and anaerobic treatment was performed in the third tank 1c.

After three months, the quality of the treated water was measured, and the results are shown in Table 3.

[0042]

[Table 3]

In Table 3 above, COD, suspended matter, n-hexane extract, TN (total nitrogen content) and TP (total phosphorus content)
Was measured according to JIS K0102 factory drainage test method. Table 3 shows that the treatment method of the present invention can reduce not only the COD but also the amounts of suspended matter, n-hexane extract, TN and TP.

Example 4 Wastewater from a rubber factory containing an amine substance and having a COD of 400 ppm was treated using the same wastewater treatment apparatus as in Example 3. However, the amount of wastewater introduced was adjusted so that the wastewater treatment amount was 12 liters / day. As a result, the C
OD could be reduced to about 40 ppm. Furthermore, in the wastewater treatment apparatus, almost no excess sludge generated by the treatment was generated. Therefore, the management of the apparatus was easy and the processing cost could be reduced.

When the same wastewater was subjected to activated carbon adsorption treatment, COD could be reduced to some extent, but in order to maintain the effect, the activated carbon had to be replaced frequently. In addition, persulfate treatment was applied to the wastewater, but COD was hardly reduced.

[0046]

According to the wastewater treatment method of the present invention, a high COD can be obtained by using an inorganic porous carrier having a specific porosity obtained by granulating and calcining a specific raw material. The wastewater can be treated as it is without diluting it with water. Further, since the treatment effect of the wastewater can be maintained longer than that of the conventional carrier, the number of backwashing can be reduced, and as a result, the treatment cost of the wastewater can be suppressed.

Furthermore, the method for treating wastewater of the present invention
Oil, suspended solids,
The amounts of nitrogen compounds, phosphorus compounds, etc. can also be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of a wastewater treatment apparatus according to a first embodiment.

FIG. 2 is a graph showing the relationship between the elapsed days of treated water and COD in Example 1.

FIG. 3 is a schematic view of a wastewater treatment apparatus according to a second embodiment.

FIG. 4 is a schematic view of a wastewater treatment apparatus according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wastewater treatment apparatus 1a 1st tank 1b 2nd tank 1c 3rd tank 2 Wastewater introduction pump 3, 3a, 3b, 3c Wastewater introduction port 4, 4a, 4b, 4c Treated water discharge port 5, 5a, 5b, 5c Wastewater circulation Pump 6, 6a, 6b Air pump 7, 7a, 7b Polarstone S-10 8, 8a, 8b Polarstone S-5 9a, 9b, 9c Gravel 10a, 10b, 10c Polarstone S-5

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomi Takeda 1-52, Ohama-cho, Amagasaki-shi, Hyogo (72) Inventor Akira Aohashi 1-52, Ohama-cho, Amagasaki-shi, Hyogo (72) Inventor Toshiyuki Yamaya Osaka 6-24-23 Awomagani Higashi, Minoh-shi (72) Inventor Kenyuki Takamatsu 2-10-15 Higashi-Awaji, Higashi-Yodogawa-ku, Osaka Inside Katayama Chemical Industry Research Laboratories (72) Inventor Masao Yabushita Higashi-Yodogawa-ku, Osaka 2-10-15 Higashi-Awaji F-term in Katayama Chemical Industry Laboratory Co., Ltd. (Reference) 4D003 AA01 AB09 BA03 CA08 EA01 EA22 FA02 FA06 FA10 4D040 BB02 BB42 BB52 BB82 4G019 FA13

Claims (6)

[Claims] 1. Clay 40 to 99 parts by weight, diatomaceous earth 0 to 30
Parts by weight, dust collection dust 1-30 parts by weight, sewage sludge incineration ash 0
After a raw material consisting of ~ 50 parts by weight is granulated and calcined, microorganisms are adhered to an inorganic porous carrier having a porosity of 20 to 60%, and wastewater having a COD of 150 ppm or more is added to the inorganic porous carrier. A method for treating wastewater, comprising contacting to reduce COD in the wastewater. 2. The wastewater C before contacting the inorganic porous carrier.
2. The method according to claim 1, wherein the OD is from 150 to 3000 ppm. 3. The inorganic porous carrier has a substantially spherical shape,
3. The treatment method according to claim 1, wherein the treatment method has an average particle diameter of 0 mm. 4. The treatment method according to claim 1, wherein the inorganic porous carrier is fixed in a wastewater treatment apparatus. 5. The wastewater according to claim 1, wherein the wastewater contains alcohols.
4 Any one of the processing methods. 6. The treatment method according to claim 1, wherein the wastewater is treated in an aerobic atmosphere or a wastewater treatment apparatus maintained under an aerobic atmosphere and an anaerobic atmosphere.