JPH03118891A - Treatment of organic sewage - Google Patents

Abstract

PURPOSE:To effectively and stably remove an org. matter and phosphorus hard to decompose in org. sewage by adjusting the sewage to specified pH and bringing the sewage into contact with a granular filter medium having org. matter adsorptivity under aerobic conditions. CONSTITUTION:An aq. mineral acid soln. 3 is injected into a pH regulating tank 2 in association with the pH value of a pH electrode 4, and the pH is regulated to 3.0-6.0. The pH-regulated water passes downward through the packed bed 7 of the granular filter medium 7' having org. matter adsorptivity in a reaction vessel 5, and the bed 7 is kept aerobic. When the water is continuously passes through the vessel 5, a microbial membrane is formed on the surface of the medium 7', hence the org. matter adsorbed and concentrated on the medium 7' is decomposed, and the org. matter is adsorbed by the microbe. Consequently, the org. matter hard to decompose in the org. sewage is efficiently and stably removed by the extremely convenient operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention removes persistent organic substances such as chromaticity components and phosphorus present in organic wastewater such as secondary treated sewage water and various industrial wastewater. It is about the method.

[Conventional technology]

Regulations on the total amount of COD in wastewater discharged into public water bodies have been implemented in some areas, and there is a growing need to reuse treated sewage and other organic wastewater, and the organic matter to be removed is also a biological substance. There has been a shift from easily degradable to difficult to decompose. As methods for removing difficult-to-decompose organic substances, adsorption methods, coagulation-precipitation methods, decomposition methods using oxidizing agents, etc. have been proposed.

Furthermore, methods for removing phosphorus from water include a coagulation-sedimentation method, a biological dephosphorization method, and a catalytic dephosphorization method. Among these, the catalytic dephosphorization method uses granular materials (phosphate rock, bone char, M
This method removes phosphorus from water by contacting it with water (e.g. gO).
It is attracting attention because it does not produce sludge that is difficult to dewater during the phosphorus removal process.

[Problem to be solved by the invention]

By the way, among the conventional methods for removing persistent organic matter,
Adsorption methods require frequent replacement or regeneration of the adsorbent;
This will significantly increase the cost of water treatment. Also,
The coagulation-sedimentation method using a coagulant has a small removal rate of 10 to 30%, and high removal performance cannot be expected. II
The decomposition method using an oxidizing agent such as □OZ+ Ch not only requires injection of a large amount of oxidizing agent in order to obtain a high removal rate, but also requires biological treatment of the liquid after oxidative decomposition.

On the other hand, the catalytic dephosphorization method has a problem in that when persistent organic substances are contained in water, these organic substances coat the surface of the particulate matter over a long period of time, resulting in a decrease in phosphorus removal performance.

One way to solve this problem was to immerse granular materials coated with organic matter in acid or alkaline solutions.
Problems such as the treatment of recycled waste fluid and the dissolution of crystallized calcium phosphate have arisen.

An object of the present invention is to solve the above-mentioned conventional problems and provide a method for efficiently and stably removing recalcitrant organic matter and phosphorus from organic wastewater.

[Means to solve the problem]

The present invention is a method for treating organic sewage, which comprises adjusting the pH of organic sewage to 3.0 to 6.0 and then bringing it into contact with a granular filter medium having an ability to adsorb organic matter under aerobic conditions. be.

The present invention is also characterized in that the treated organic lη water is further brought into contact with granular materials having phosphorus removal ability in the presence of calcium and alkali.

Furthermore, in the present invention, the pn of organic lη water is 8.5 to 9.5.
This is a method for treating organic wastewater, which is characterized in that it is brought into contact with a granular filter medium that has the ability to adsorb organic matter under aerobic conditions after being adjusted to After adjusting the pH of the wastewater to 8.5 to 9.5, the wastewater is brought into contact with a granular filter medium having the ability to adsorb organic matter under aerobic conditions, and further brought into contact with granules having the ability to remove phosphorus in the presence of calcium and alkali. It is also characterized by forcing.

[For production]

The operation of the present invention will be explained below with reference to the drawings showing an example of the embodiment.

In FIG. 1, secondary treated sewage water, which is raw water 1, is introduced into a pH adjustment tank 2, and a mineral acid solution 3 is injected in conjunction with the pH value of a PO electrode 4 to adjust the pH to 3.0 to 6.0. , preferably adjusted to 3.0 to 5.5. In order to reduce the amount of injected mineral acid solution 3, it is preferable to allow biological nitrification to proceed in the preceding secondary sewage treatment step to reduce the M-alkalinity component.

This pH-adjusted water flows into the reaction tank 5 through the inflow pipe 6. Inside the reaction tank 5, a granular filter material 7 having an ability to adsorb organic matter is provided.
The packed bed 7 of ' is supported by the lower gravel layer 8, and the inside of the packed N7 is maintained in an aerobic state while the inflow p It 2m regulated water flows through these in a downward flow.

As a means of maintaining the inside of the packed bed 7 in an aerobic state, there are methods of blowing air or a gas containing at least oxygen into the packed bed 7, or blowing air directly into the raw water 1 to dissolve oxygen, or a method of dissolving oxygen by blowing air or the like directly into the raw water 1. Examples include a method in which acid is supplied to the container and then water is passed through the packed bed 7 after aeration, or a combination thereof is used, and the method is not particularly limited. In the case of the type in which air or the like is blown into the packed bed 7, the air can be blown from various levels of the packed bed 7, but it is preferable to blow air from below the packed bed 7. A diffuser pipe 9 connected to a blower 10 is provided in the layer 8 to efficiently uniformly distribute oxygen throughout the packed layer 7 and to maintain the entire filled layer 7 in an aerobic state at all times. As shown in the illustrated example, the diffuser pipe 9 is preferably located below the packed bed 7, but may also be located within the packed bed 7. Further, instead of the gravel layer 8 supporting the filling N7, a support plate 13 (see No. 20) such as a perforated plate may be used, and in that case, the position of the aeration pipe 9 may be above or below the support plate.

When water continues to flow through the reaction tank 5 in this way, a microbial film is formed on the surface of the granular filter medium 7', and the organic matter adsorbed and concentrated on the granular filter medium 7' is decomposed, and the organic matter is adsorbed by the microorganisms. The treated water flows out of the tank from the treated water outflow pipe 11. Such reactions proceed efficiently under specific conditions of pH 3.0 to 6.0.

In addition, the water flow direction to the packed bed 7 of the pH 3ll regulated water is as follows:
Instead of the downward flow as described above, the upward flow can also be used.

If such processing continues for a long time, clogging will occur in the filling N7, and water flow resistance will increase. When a certain water flow resistance is reached, cleaning air is discharged from the air cleaning pipe 12 from the lower part of the gravel layer 8, and cleaning water is discharged from the treated water outflow pipe 11 to remove SS trapped in the packed bed 7 and to remove microorganisms. Part of the membrane is peeled off.

The granular filter medium 7' may be made of activated carbon, bone charcoal, zeolite, or the like having a large specific surface area (preferably 100n).
/g or more) can be used, but activated carbon and bone char are most preferred. When such a granular filter medium is used, heavy metals can also be removed in the pH range (3.0 to 6.0) of the above operation.

In the example shown in FIG. 2, a granular filter medium 7' with a large particle size is used as the granular filter medium 7' having an ability to adsorb organic matter, and this packed material N7 is supported on a support plate 13 such as a perforated plate. Air is blown from the blower 10 directly onto the water surface below the support plate 13, and its action is almost the same as in the case shown in FIG.
By circulating the treated water to the upper part of the reaction tank 5, the treatment efficiency can be increased.

Moreover, FIG. 3 shows an embodiment in which not only COD□ but also phosphorus in the raw water 1 is effectively removed. In FIG. 3, raw water 1, which is secondary treated sewage water, is treated with mineral acid solution 3 to a po3. The method of adjusting the temperature to 0 to 6.0, maintaining it in an aerobic state by blowing air, etc., and contacting it with a granular filter medium in the reaction tank 5 is the same as the treatment method shown in Fig. 1 or Fig. 2 described above. However, when treated in this way, COD in raw water
At the same time as □ is removed, carbonic substances are also removed. These substances are known to inhibit the phosphorus removal reaction in the catalytic dephosphorization method using phosphate rock, etc.
Since the water has already been removed as described above, calcium and alkali 15 are added to the treated water from the reaction tank 5, and after adjustment in the adjustment tank 16, the water is led to the catalytic dephosphorization tank 17 to remove phosphorus from the water.

Furthermore, in the treatment shown in FIGS. 1 and 2, instead of the mineral acid solution 3 injected into the raw water 1, an alkaline solution is injected to bring the pl+ of the raw water 1 to 8.5 to 9.5. After adjustment, it is also effective to contact a granular filter medium having an ability to adsorb organic matter under aerobic conditions. Such treatment under alkaline conditions is similar to the above-mentioned treatment under acidic conditions (pH 3.0~
Although the efficiency was slightly lower than the treatment in 6.0), the removal rate of COD□ was better than the conventional biological activated carbon treatment in the pl+ range.

When the catalytic dephosphorization method is combined with this COD□ removal under alkaline conditions, the combination is as shown in FIG. 4. That is, in FIG. 4, after adding mineral acid solution 3 to raw water l and removing carbonated substances by air blowing etc. in decarbonation tank 18 (DO is simultaneously supplied into the raw water at this time), in adjustment tank 16 After adjusting the calcium concentration and at the same time adjusting the pN to 8.5 to 9.5 with calcium and alkali 15, water is passed through a reaction tank 5 filled with activated carbon to remove COD□,
Next, the water is introduced into a catalytic dephosphorization tank 17 to remove phosphorus from the water.

In this case, when the activated carbon packed bed is aerated, carbonic substances in the water are re-inhaled, so aeration in the reaction tank 5 is not performed.

In addition, when the reaction tank 5 and the catalytic dephosphorization tank 17 are combined into one as shown in Fig. 5, and an activated carbon packed bed is laminated on top of the phosphate ore packed bed to form a COO, phosphorus removal tank 19, the equipment and process can be simplified.

〔Example〕

Example 1 Secondary treated sewage water was used as raw water and 1% sulfuric acid or N
Add aOH 1% solution and reduce its pll to 2.0.3.5
4.5. 5.5. 6.5. 7.5. 8.5.
9.0. Water was adjusted to 9.5° and 10.0° in a downward flow at a rate of 33 cc/min, and at the same time, air was supplied into the column at a rate of 0.11/min using an aeration method. At this time, the pH during each water flow and the ability to remove COD□ in water were as shown in Table 1.

In addition, the raw water quality is C0Ds, 10.0-15.0 (■/l1
)SS 1.5~3.0(■/N)M
-Alkalinity 100-150 (■/1)Ca
It was 60-80 (mir/j).

As is clear from Table 1 below, at the pH of the present invention, the removal rate of COD Activated carbon regeneration was not necessary during the one-year experimental period.

Example 2 Filled with 21 pieces each of activated carbon, bone charcoal, and zeolite with an effective diameter of 0.80, and equipped with an aeration method at the bottom, inner diameter 50n x height 3
000 m of raw water of the following quality is added to each cylindrical column.
The results of water flow at 33 cc/min in a downward flow with 1 liter of 4.5 are as shown in Table 2.

Raw water quality: COD□ 9.8-17.0 (Akebono/Ri SS
1.6-3.5 (■/N) M-alkalinity 98-120 (■/It) Ca
60-80 (If/J) Below margin table note Treated water quality is the annual average value.

Example 3 Slaked lime and calcium chloride were added to the treated water of Example 1 with a pH of 4.5 to give a pH of 9.0 and a Ca of 70 to 90*/7.
! Phosphate rock 11 with an effective diameter of 0.45 m was adjusted to
When water was passed through a cylindrical column with an inner diameter of 50mm and a height of 3000mm filled with water at a rate of 30ee/min in a downward flow for about one year, the phosphorus removal rate was 85% (raw water phosphorus concentration 1.0%/min).
l, effluent water phosphorus concentration 0.15■/l), coo
, a 4M removal rate of 87.5% was obtained.

On the other hand, as a comparative example, the raw water (secondary treated sewage water) of Example 1 was treated with aeration CG/L=5) in a decarbonation tank with a residence time of 15 minutes under the condition of pl+4.5, and then treated with slaked lime and calcium chloride. was added, pH 9.0, Ca 60-80owr/
When the water was adjusted to β and passed through the cylindrical column in the same manner as above, the phosphorus concentration in the effluent tended to rise slightly, and the annual average phosphorus removal rate was 609A (raw water phosphorus concentration 1.0/1.
Effluent water phosphorus concentration was 0.4■/1) COD□ removal rate was 10%.

Example 4 The raw water (secondary treated sewage water) of Example 1 was aerated (G/L
=5) After the treatment, slaked lime and calcium chloride were added to adjust the pl+9.0 and Ca70 to 90 mg/1. Then, add 24 pieces of activated carbon with an effective diameter of 0.8
A packed cylindrical column with an inner diameter of 50 tix and a height of 3000 mm was passed with water at 33 cc/min in an upward flow.

When this treated water was passed in an upward flow at 30 cc/min through a cylindrical column with an inner diameter of 50 fins and a height of 3,000 m packed with 11 phosphate rocks with an effective diameter of 0.450, the water flowed upward at a rate of 30 cc/min for about 1 year.
A phosphorus removal rate of 70% (raw water phosphorus concentration 1.0/1. effluent water phosphorus concentration 0.3//) and a COD□ removal rate of 75% were obtained.

On the other hand, as a comparative example, the same raw water was decarboxylated and pHl! After leveling, 21 pieces of sand with an effective diameter of 0.8 m were
Water was allowed to flow upward into a filled cylindrical column with an inner diameter of 50 mm and a height of 3000 mm. This treated water was collected using an effective diameter of 0.45 as
Inner diameter 50mm x height 3000n filled with 11 pieces of phosphate rock
When water was passed through a positive cylindrical column at a rate of 30 cc/min in an upward flow, the phosphorus concentration in the effluent tended to rise slightly, and the phosphorus removal rate was on average 50% per year (raw water phosphorus concentration 1.0/l). ,
Effluent water phosphorus concentration 0.5■/1), COD□ removal rate 10%
It became.

C Effect of the invention] As described above, according to the present invention, the ρ11 of organic wastewater
To efficiently and stably remove recalcitrant organic matter from organic sewage through an extremely simple operation of simply adjusting the water to an optimal range and bringing it into contact with a granular filter medium that has the ability to adsorb organic matter under aerobic conditions. In addition to this, efficient phosphorus removal can also be expected by following the catalytic dephosphorization process.

[Brief explanation of drawings]

FIG. 1 to FIG. 5 are explanatory diagrams each showing a mode of implementation of the present invention. DESCRIPTION OF SYMBOLS 1... Raw water, 2... pH adjustment tank, 3... Mineral acid solution, 4... pH electrode, 5... Reaction tank, 6... Inflow pipe, 7... Filled bed, 7'... Granular filter material, 8... Gravel layer, 9... Air diffuser pipe, 10... Air blower, 11... Treated water outflow pipe, 12... Air cleaning pipe, 13... Support Plate, 14... Circulation pump, 15... Calcium and alkali agent, 16... Adjustment tank, 17... Catalytic dephosphorization tank, 1B... Decarbonation tank, 19... Con. Phosphorus removal tank.

Claims (4)

[Claims] (1) A method for treating organic sewage, which comprises adjusting the pH of the organic sewage to 3.0 to 6.0 and then bringing it into contact with a granular filter medium having an ability to adsorb organic matter under aerobic conditions. (2) After adjusting the pH of organic wastewater to 3.0 to 6.0, it is brought into contact with a granular filter medium that has the ability to adsorb organic matter under aerobic conditions, and the phosphorus removal ability is further improved in the presence of calcium and alkali. A method for treating organic wastewater, which comprises bringing it into contact with particulate matter. (3) A method for treating organic sewage, which comprises adjusting the pH of the organic sewage to 8.5 to 9.5, and then bringing the organic sewage into contact with a granular filter medium having an ability to adsorb organic matter under aerobic conditions. (4) After removing as much carbonic acid from the water as possible and adjusting the pH of the organic wastewater to 8.5 to 9.5, it is brought into contact with a granular filter medium capable of adsorbing organic matter under aerobic conditions, and then A method for treating organic wastewater, which comprises bringing it into contact with granules having phosphorus removal ability in the presence of calcium and alkali.