JPS61242685A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To remove effectively oil including water-soluble oil or COD in waste water by bringing waste water into contact with coal or coke having specified grain size. CONSTITUTION:Waste water is brought into contact with coal or coke having <=5mm grain size in a mixing tank or an adsorption tower. Namely, since coal or coke having excellent physical and chemical adsoptive power and also having high adsorptive power to a substance having strong polarity is used, oil or COD in industrial waste water can be effectively treated, coal or coke, an adsorbent, obtained only by crushing already oxidized coal or coke in specified grain size need not be reactivated unlike activated carbon and hence is far cheaper than activated carbon, a compound and multistage apparatus is not necessitated and water-soluble oil can be removed with high efficiency with a simple means such as mixing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a wastewater treatment method, and particularly to a wastewater treatment method for separating and removing oil or COD from industrial wastewater.

Conventional technology and its problems Wastewater treatment methods are broadly classified into the same liquid separation method, physicochemical treatment method, biological treatment method, heat treatment method, etc. The method to be applied, operating conditions, etc. are determined depending on the concentration, type of coexisting substances, and concentration isobaric.

A wastewater treatment method for the purpose of separating and removing oil or COD in industrial wastewater, and 1-, includes coagulation separation, chemical treatment, and activated carbon treatment among conventional physicochemical treatment methods.

Activated sludge treatment among biological treatment methods is applied. However, if a high treatment effect such as removing oil or COD to several any/z after treatment is desired, it is necessary to take measures such as making these treatment devices multiple and multistage, making the treatment process complicated. Not only is the processing cost high, but the processing cost is also high. In addition, it has been difficult to remove water-soluble (emulsified) oils among oils at a rate of several mf/li even by the above-mentioned composite/multistage treatment.

Purpose of the Invention This invention was made in view of the above-mentioned conventional situation, and its purpose is to propose a wastewater treatment method that can effectively dispose of and remove COD or oil containing water-soluble oil. .

Structure of the Invention The wastewater treatment method according to the present invention is characterized in that the wastewater is purified by contacting it with coal or coke with a particle size of 5 Mll or less, and the contact between the coal or coke and the wastewater is carried out by a mixing tank method. Alternatively, the method is characterized in that it is carried out by an adsorption tower system in which wastewater is passed through a coal bed or a coke bed.

That is, the present invention is a method of treating wastewater using coal or coke as an adsorbent.

Coal is known to have excellent moisture adsorption ability, as bituminous coal and lignite have traditionally been used as raw materials for activated carbon. However, in the case of activated carbon, it is manufactured by a scum activation method, etc., so the manufacturing process is complicated and expensive, and its adsorption capacity for highly polar organic substances is also low.

As a result of various studies on how to obtain an adsorbent that is cheaper than activated carbon and has a higher adsorption capacity, the inventors found that by bringing wastewater into direct contact with pulverized coal or coke to a particle size of 5 fl or less, the inventors found that they had a higher desorption rate than activated carbon. Oil rate, carbon removal
It has been found that the OD rate can be obtained. When we investigated the cause, we found that it was due to oxidation of the coal.

That is, it is presumed that when coal is oxidized, oxidation products that contribute to chemical adsorption in the coal are produced, and the physical adsorption capacity increases. In the case of coke, since coal is heat-treated, oxidation products that contribute to chemical adsorption are sufficiently produced, and physical adsorption capacity due to decomposition is also sufficient.

As mentioned above, coal and coke are sufficiently effective as adsorbents for wastewater treatment, but it is advantageous to increase the specific surface area for rounding to obtain higher adsorption power. Therefore,
In this invention, the particle size of coal or coke is limited to 5a+n or less. That is, coal or coke with a particle size of more than 5 m has a small specific surface area, resulting in a decrease in wastewater treatment efficiency. The preferred particle size range is 0.3 to 1.0 μm in the case of the adsorption tower method, and 74 to 300 μm in the case of the mixing tank method.

Figure 1 shows an example of the equipment configuration of the adsorption tower treatment method of the present invention, in which (1) is a waste water tank, (2) is a water supply pump, and (3) is a waste water tank.
indicate adsorption towers, respectively. The lower layer of the adsorption tower (3) is sand M.
(4), and the upper layer is formed of a coal layer or coke layer (5) with a grain size of 5 mm or less. The structure is such that wastewater is supplied from the top, passes through the coal J- or coke layer (5) and sand N (4), and is discharged from the bottom.

In addition, the mixing tank treatment method is as shown in Fig. 2, which shows an example of the equipment configuration.
3. Stirring device Qli Q! , a drainage pump α, a solid-liquid separation tank (14), and a discharge pump (1), and coal or coke Oe with a particle size of 5WR11 or less is charged into the mixing reaction tank 03. Note that this treatment method is a circulation system in which all unreacted adsorbent is returned to the mixing reaction tank 03 again.

In the case of the adsorption tower treatment method shown in Fig. 1, industrial wastewater is once collected in a wastewater tank (1) and then sent to an adsorption tower (3) by a water supply pump (2). The wastewater sent to the adsorption tower (3) is removed from the wastewater as it passes through some coal seams or coke H (5), and is further filtered through the lower iron layer (4). and discharge from the bottom.

Note that sand practice is not necessarily required.

In the case of the mixing tank system shown in Fig. 2, the wastewater collected in the wastewater tank αJ is sent to the mixing reaction tank α3 by the water supply pump (6), where coal or Koknu O duck is charged and stirred by the stirring device α0. By mixing, oil and COD'i are removed. Next, the same liquid separation tank α→
The purified water is separated from the adsorbent (coal or coke). The purified water is overflowed and discharged, and the adsorbent that has settled and separated is pumped out from the bottom of the tank.
The unreacted adsorbent is returned to the mixing reaction tank (2) and used for circulation.

In addition, the amount of coal or coke used as an adsorbent relative to the amount of wastewater is as follows in the case of an adsorption tower treatment method:
The layer thickness can be determined appropriately depending on the volume of the adsorption tower, but if coal or coke has a particle size of 0.3 mm or less, the pressure drop will be large, resulting in a reduction in processing capacity, so the layer thickness should also be determined by considering the particle size. .

On the other hand, in the case of a mixing tank system, the mixing ratio is preferably determined from the previously investigated adsorption properties of coal and coke and the wastewater concentration.

Example 1 Coal having the composition shown in Table 1 and coke having the properties shown in the same table were mixed with particle sizes of 2 to 411 μm and 74 μm or less, and 411 scraps to 7 μm, respectively.
When pulverized to each particle size of 4 μm, 10% by weight of the adsorbent of each particle size was added to a water-soluble hydraulic oil with a concentration of 0.1 to 0.2% by weight with the main composition shown in Table 2, and the mixture was stirred and mixed for about 60 minutes. De-C
The OD rate and oil removal rate were compared with those using activated carbon.
Shown in the table.

Note that the COD removal rate and oil removal rate are values determined by the following formula.

As is clear from Table 3, compared to activated carbon, which has been represented as a conventional advanced water treatment material, it has 40% more adsorption power for coal and coke in terms of COD removal rate, and has a higher oil removal rate than activated carbon. The effect was confirmed. In the case of coal and coke, the smaller the particle size, the better the adsorption power.

Table 1 Table 2 Table 3 Table 3 Example 2 A 1.2-meter thick layer consisting of coal having the composition shown in Table 4 or coke having the properties shown in Table 4 in the upper layer of an adsorption tower with a radius of 2 m.
A coal seam or coke layer of 1.0 m thick is placed in the lower layer. Om
2, oil content 65 ppm, CO
D 360ppm, PH8.5-9.0 wastewater 200
Treated the door. The results are shown in Table 5. In addition, the particle size of coal or coke in this example is 0.6 to 5. O
Imφ (2,0~511Mφ40%, 02m+1φ60
%), and the particle size distribution of the sand was 0.6 to 5 mm.

From Table 5, the adsorption tower treatment method also showed high COD removal rates and oil removal rates.

Table 4 Table 5 Effects of the Invention As explained above, the wastewater treatment method according to the present invention has excellent physical adsorption power and chemical adsorption power. Because it uses coke as an adsorbent, it is extremely effective in treating oil or COD in industrial wastewater.Also, the adsorbent, coal mak, does not require activation treatment like coke, and has already been oxidized. Because it can be used by simply pulverizing the carbon to a predetermined particle size, it has the effect of being much cheaper than activated carbon. It is possible to remove water-soluble substances with a high oil removal rate using a simple method such as a mixing treatment method, and it is highly effective in tertiary treatment or final treatment for environmental protection measures.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the equipment configuration of an adsorption tower treatment method according to the present invention, and FIG. 2 is a schematic diagram showing an example of the equipment configuration of the mixing tank treatment method as well. 1.11...Waste water tank, 2,12...Water pump, 3
... Adsorption tower, 5... Coal or coke layer, 13.
...Mixing reaction tank, 14...Solid-liquid separation tank, 15...
Stirring device, 19...coal or coke.

Claims (1)

[Claims] 1. A wastewater treatment method characterized by purifying wastewater by bringing it into contact with coal or coke with a particle size of 5 mm or less. 2. Claim 1, characterized in that coal or coke and wastewater are brought into contact by a mixing tank method or an adsorption tower method in which wastewater is passed through a coal bed or a coke bed.
Wastewater treatment method described in section.