JPH04150988A - Regeneration of activated carbon - Google Patents

Abstract

PURPOSE:To stabilize treatment capacity at a low cost over a long period of time by aerobically aerating activated carbon to be regenerated after treatment in water whose concn. of org. matter is lower than that of water to be treated. CONSTITUTION:In a regeneration tank 5, the adsorbed org. matter on the surface of activated carbon is aerated by air along with the saturated adsorbing activated carbon 7 taken out of an activated carbon packed tank 2 or 2' to be subjected to oxidative decomposition by the action of bacteria. The regenerated activated carbon 8 is returned to the activated carbon packed tank 2 or 2' and the treated water 4 used in the regeneration tank 5 is returned to the activated carbon-packed tank 2 along with water 1 to be treated as a withdrawing liquid 6 or discharged out of the system as it is. When the org. matter adsorbed on activated carbon is not desorbed according to the kind thereof by the concn. gradient of the org. matter, said org. matter can be desorbed by auxiliarily using an inorg. acid such as hydrochloric acid or sulfuric acid, alkali such as NaOH or Ca(OH)3 or org. solvent such as methanol or ethanol.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for regenerating activated carbon, and particularly to a method for regenerating activated carbon after treatment when organic matter in water to be treated is adsorbed and removed by activated carbon.

[Conventional technology]

Conventionally, dry or wet heating regeneration methods have been widely used as methods for regenerating activated carbon. In addition, chemical regeneration methods using chemicals such as caustic soda are also used because they require less investment in equipment for regeneration equipment and are easy to operate.

Furthermore, a biological regeneration method is also known in which the organic matter adsorbed on the surface of activated carbon is decomposed by the action of microorganisms.

However, in the case of the thermal regeneration method, ■ the activated carbon loss is relatively large at 3-10% after regeneration times, ■ the material inside the furnace is consumed rapidly because it is operated at high temperatures, and ■ the temperature and gas conditions are strictly limited. ■There are disadvantages such as expensive equipment. Although the chemical regeneration method does not require special equipment such as a heating furnace, there are problems such as high costs for post-processing of the chemicals and desorption/regeneration liquid. On the other hand, biological regeneration methods have the advantage of not requiring special equipment or chemicals;
Regeneration takes a long time, and there is a limit to the extent to which adsorption performance can be recovered.

[Problem to be solved by the invention]

An object of the present invention is to solve the problems of the prior art as described above and to provide a method for efficiently regenerating activated carbon used for water treatment at low cost.

[Means to solve the problem]

In order to achieve the above object, in the present invention, in the adsorption and removal treatment of organic matter in water to be treated using activated carbon, the activated carbon to be regenerated after treatment is aerobically heated in water with a lower concentration of organic matter than the water to be treated. This is a method for regenerating activated carbon, which is characterized by aeration.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic flow diagram showing an example of the present invention. In FIG. 1, treated water 1 flows into activated carbon filling tanks 2 and 2' filled with activated carbon 3 and 3', and is discharged as treated water 4. Here, a part of the treated water 4 is guided to the regeneration tank 5. In the regeneration tank 5, the saturated adsorbed activated carbon 7 taken out from the activated carbon filling tank 2 or 2' is aerated with air, and the adsorbed organic matter on the surface of the activated carbon is oxidized and decomposed by the action of microorganisms. At this time, aerobic microorganisms such as activated sludge may be separately added to the regeneration tank 5, but microorganisms may adhere to and proliferate on the surface of activated carbon used in the treatment of sewage or tap water. In such cases, it is not necessarily necessary to separately add aerobic microorganisms.

The regenerated activated carbon 8 is returned to the activated carbon filling tank 2 or 2', and the treated water 4 used in the regeneration tank 5 is returned to the activated carbon filling tank 2 together with the water to be treated 1 as a bowing liquid 6, or it is directly removed from the system. Discharge.

The present invention is a method for regenerating activated carbon, which is characterized in that organic matter concentrated on the surface of activated carbon is eluted in a regeneration tank, and the eluted organic matter is oxidized and decomposed by the action of microorganisms.

Therefore, depending on the type of organic matter adsorbed on activated carbon, the organic matter may not be desorbed to the lighter side only by the concentration gradient.

In such cases, inorganic acids such as hydrochloric acid and sulfuric acid, Na0
)1, it is also possible to desorb using an auxiliary alkali such as Ca(DH)a, an organic solvent such as methanol or ethanol, or other substances with a higher affinity than the organic matter in the water to be treated, such as phenol or benzoic acid. It is.

In this case, a certain amount of activated carbon is taken out from the activated carbon filling tank and put into the regeneration tank 5, and after desorption of acids, alkalis, organic solvents, etc. proceed, another activated carbon and treated water are put in, and air is supplied. Aerate and regenerate. Furthermore, without separately performing the desorption operation and the regeneration operation as described above, the regeneration may be performed while adding acid, alkali, organic solvent, etc. in the regeneration tank 5 into which activated carbon and treated water are input. When performing regeneration by adding acid or alkali, the pH is preferably maintained at 4.0-10.0. Note that it is more effective to perform the regeneration operation in the regeneration tank 5 several times, and natural water such as tap water, well water, river water, etc. may be used instead of the treated water 4.

[Effect]

Generally, the adsorption power of activated carbon for organic matter in water varies greatly depending on temperature, pH, coexisting substances, and other conditions. Therefore, by considering the properties of the organic matter in the water to be treated and the above-mentioned conditions, it is possible to desorb the organic matter adsorbed on the activated carbon to the lighter side. Furthermore, depending on the type of organic substance, it can be easily desorbed by lowering the equilibrium adsorption concentration. The present invention actively utilizes the desorption operation of adsorbed organic matter from activated carbon, and the desorbed organic matter is rapidly oxidized and decomposed by microorganisms in the regeneration tank. Therefore, compared to the conventional biological regeneration method in which raw water (water to be treated) is led to a regeneration tank, or the method in which nutrients such as BOD, nitrogen, and phosphorus are added separately, regeneration can be performed in a shorter time and more efficiently. Ru.

FIG. 2 shows an investigation using chlorbenzoic acid (0-CIBa) and its degrading bacteria to investigate the biodegradation characteristics of organic matter adsorbed on activated carbon. A predetermined amount of granular charcoal was added to the medium 200- in Table 1, and the mixture was shaken for 72 hours to reach an equilibrium adsorption state.

The results are shown in Table-2.

Table: Composition of basic medium <g/l) a: Dissolved in 0°Na0)1 Og/l) 0rn! Adjust the concentration by adding O times and sterilize separately Table-2 Experimental system settings "Thcl-: Remained on the pale side. - Theoretical value of Cl- released from CIBa. After that, chlorbenzoic acid-degrading bacteria were added, The concentration of chlorbenzoic acid on the light side and the concentration of chlorine ions liberated by biodegradation were measured over time.Thc indicated by the broken line in Figure 2
The chlorbenzoic acid (chlorbenzoic acid) remaining on the light side after the addition of activated carbon
This figure shows the concentration of chloride ions liberated when o-CIBa) is completely biodegraded.

The figure shows that the chlorbenzoic acid on the lighter side was rapidly decomposed after the addition of the degrading bacteria, and chloride ions were liberated accordingly. However, the amount of chlorine ions released to the light side was greater than the theoretical value (Thcl-) in all experimental systems. This indicates that the chlorbenzoic acid previously adsorbed on the activated carbon was decomposed. However, the results of this experiment show that the amount of chlorbenzoic acid on the light side is not constant, as it is a phenomenon in a batch system, but decreases as it is consumed by degrading bacteria. That is, it is considered that the chlorbenzoic acid adsorbed on the activated carbon was decomposed as a result of conditions in which it was easily desorbed due to a decrease in the equilibrium adsorption concentration and was desorbed to the lighter side.

Furthermore, in the experimental system where the activated carbon concentration was 5000/1, the desorption rate of chlorbenzoic acid was slow due to the low initial equilibrium absorption concentration, and it is thought that this is why it took time to liberate chlorine ions.

From the above results, it has become clear that the organic matter adsorbed on activated carbon is decomposed by microorganisms, and in this case, the ability to desorb from the activated carbon is an important factor governing the biodegradability of the adsorbed organic matter.

FIG. 3 shows the results of investigating the desorption properties of chlorbenzoic acid. 600■/1 chlorbenzoic acid solution to 5000■/1
of activated carbon and shaking at 28°C for 40 hours, the equilibrium adsorption concentration was 200 mg/j! ), the concentration of the solution was varied with a predetermined amount of pure water, and the concentration of chlorbenzoic acid eluted on the lighter side was measured over time. As is clear from the figure, the equilibrium adsorption concentration was changed from 200 mg/i to Omg/i.
The system changed to 1 showed the highest desorption performance, and the smaller the amount of change, the smaller the amount of desorption. Therefore, the second
From the results shown in Figures and Figure 3, in the case of chlorbenzoic acid, it is possible to desorb it from activated carbon simply by changing the equilibrium adsorption concentration, and in this case, the greater the difference in concentration from the equilibrium adsorption concentration, the greater the regeneration effect. But it's hurakato! It was.

Table 3 shows activated carbon used in advanced treatment of sewage.
These are the results of measuring the amount of TOP eluted by immersion in various types of water after treating it by steaming to kill microorganisms attached to the surface.

Table 3 Amount of TOC eluted from activated carbon: Amount of TOC eluted to the drained liquid side after immersion for 24 hours Adjusted with Oo Na leaf From Table 3, it is found that the amount of TOC eluted is higher in the treated water than in the treated water, and that p)l is higher. The result was that the amount of TOC produced was large. In this way, in the case of water containing multi-component organic substances such as sewage, as in the example of chlorbenzoic acid mentioned above, a significant desorption effect cannot be observed with only a concentration gradient, and it is effective to maintain the water under alkaline conditions. It was a target. This is because sewage contains a relatively large amount of substances such as humic substances, which are generally difficult to be desorbed by concentration gradients alone, and it is effective to remove tate using a negatively charged ladle under alkaline conditions. It is thought that it has become .

Therefore, in order to decompose and remove organic matter adsorbed on activated carbon in a regeneration tank, it is necessary to set the conditions of the regeneration tank after fully considering the adsorption properties of the adsorbed organic matter.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples.

Example-1 An example of the present invention will be described in which phenol wastewater (artificial wastewater) is used.

The activated carbon is regenerated as shown in Fig. 1, where the activated carbon is sequentially pulled out from the top of the activated carbon filling tank 2 and the treated water is introduced into the regeneration tank 5.
Activated carbon 7 was added to the tank and aerated with air. The conditions for implementation are as follows.

(1) Raw water　Phenol artificial wastewater Dissolve the following chemicals in tap water 11. I understand.

100 mg of phenol, 20 ■ of ammonium sulfate, 5 ■ of potassium phosphate (2) Activated carbon filled tank diameter: 100-1 height: 1500 mm Activated carbon layer thickness: 700-800 mm 5V 1.50hr-(LV 50m/d) Before starting water flow Activated sludge enriched with phenol was added to allow phenol-degrading bacteria to adhere to the activated carbon surface.

(3) Regeneration tank diameter 300 mm, height 600Ill1
mWater filling capacity: 0.03 m3 Aeration is carried out in batches for 8 hours, after which water is withdrawn and treated water is introduced again for 8 hours of aeration. The recycled activated carbon is returned to the bottom of the activated carbon filling tank.

As a control, an experimental device of the same type and under the same conditions without a regeneration tank was set up.

The implementation results are shown in Figure 4. In the control area, the quality of activated carbon-treated water gradually deteriorated, whereas in the experimental area where a regeneration tank was installed, there was almost no change in the quality of treated water during the 120-day experimental period, and the effect of the regeneration treatment was remarkable. .

Example-2 Another example of the present invention will be described. In FIG. 1, the activated carbon 7 is sequentially pulled out from the top of the activated carbon filling tank 2.
Activated carbon was introduced into the regeneration tank 5 into which the treated water was introduced, and aerated with air. The pl-1 of the regeneration tank was adjusted to 8.5. The conditions for implementation are as follows.

(1) Raw water (water to be treated) Heavy sewage treatment plant secondary treated water in K$ Average water quality: BOD 14■/1, COD 13mg/j! , TOC11■/β, SS 5! l1g/l, pH6,8 (2) Activated carbon filling tank Average water quality: BOD 3mg/A! , COD 6mg/A.

TOC5■/1, SS 1mg/l, pH6.5 (3) pH adjusting agent NaOH solution (4) Activated carbon filling tank diameter 200 mm, height 2500 nun activated carbon layer thickness
1000-120011IIISV 1.50hr
(LV 50m/d) (5) Regeneration tank diameter 500
+n+n, height 1000 mm, water filling capacity 0.1 m' Aerate for 12 hours in batches, then drain the water, introduce treated water again, and aerate for 12 hours. The recycled activated carbon is returned to the bottom of the activated carbon filling tank.

As a control, an experimental device of the same type and under the same conditions without a regeneration tank was set up.

The implementation results are shown in Figure 5. In the control area, the quality of activated carbon-treated water gradually deteriorated, whereas in the experimental area with a regeneration tank, there was almost no change in the quality of the treated water during the 400-day experimental period, and treatment was possible without the need to replenish fresh charcoal. Ta.

Example-3 In Figure 1, the experimental system that leads raw water to the regeneration tank (control area)
The regeneration ability was compared with the case where a system was installed and the treated water was introduced for regeneration. Other conditions were the same as in Example-2.

The implementation results are shown in Figure 6. Although each experimental system was regenerated on the 250th day after the start of operation, the regeneration effect was insufficient in the system where raw water was introduced into the regeneration tank, and the T of the treated water was
The OC concentration increased to approximately 7 mg/β. On the other hand, in a system using treated water, the TOC of the treated water was
The concentration was always stable at around 4 mg/f.

〔Effect of the invention〕

As described above, according to the present invention, the method for regenerating activated carbon can be improved as follows.

(1) Since on-site regeneration is possible without the need for special equipment, costs are low and processing performance is stable over the long term.

(2) Organic matter adsorbed on activated carbon is regenerated under conditions that actively desorb it, so it can be regenerated more efficiently and in a shorter time than conventional biological regeneration methods.

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing an example of the present invention, and FIG. 2 is a flowchart showing an example of the present invention. This is a graph obtained by measuring acid concentration and chlorine ion concentration liberated by biodegradation over time. Fig. 3 is a graph in which the desorbability of chlorbenzoic acid was investigated; Figs. 4, 5, and 6. is a graph showing the results of Examples 1 to 3. 1: Raw water (water to be treated), 2.2': Activated carbon filling tank, 3.
3': activated carbon, 4: treated water, 5: regeneration tank, 6: withdrawal liquid, 7: saturated adsorption activated carbon, 8: regenerated activated carbon, 9: diffuser plate, 10: chemical addition, 11: pl (controller patent applicant Ebara Infilco Co., Ltd. Ebara Research Institute Co., Ltd. Director Yoshimine Matsu Hashirama 1) Large 1st figure 5th figure removed Time opening (minutes) ・v@a, vt degree 2■-$/F" I 5Chl/
L 6 %Isu 11/l 200z> /R→l O
Og / PC early rut absorption Asahi encounter EDtl/f → bag 9/branch O
Half-equal suction 1 spooky cliff 2 ■ 佽 2 no! → O*＞/ 1 Figure 4 O ■ 4o ω eK) 1ω 100 is the number of colored days (days) 2C1 罎E 入社入日, 4ri, (days)

Claims (1)

[Claims] 1. In the adsorption and removal treatment of organic matter in water to be treated using activated carbon, the activated carbon to be regenerated after treatment is aerobically aerated in water with a lower concentration of organic matter than the water to be treated. Characteristic activated carbon regeneration method. 2. The method for regenerating activated carbon according to claim 1, wherein the aerobic aeration is performed by adding an acid, an alkali, an organic solvent, or a substance having a higher affinity than the organic matter in the water to be treated.