JP2014004511A - Method for regenerating activated carbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating activated carbon, in which ignition residues can be removed and adsorptivity of the activated carbon can efficiently be restored.SOLUTION: When adsorptivity of the activated carbon, which is used in a water treatment facility and to which at least one of organic matter and inorganic matter is stuck, is restored, firstly, the resulting activated carbon is cleaned in an acid solution and secondly, the cleaned activated carbon with acid is heat-treated by a heating means. As a result, the ignition residues of the activated carbon can be removed in advance by the cleaning with acid before the heat treatment. Since the activated carbon of an ignition residue-removed state is heat-treated, the adsorptivity of the activated carbon can efficiently be restored without being disturbed by the ignition residues thereof.

Description

  The present invention relates to a method for regenerating activated carbon for regenerating the adsorption performance of activated carbon to which at least one of an organic substance and an inorganic substance attached is used in a water treatment facility.

  In water treatment facilities such as water purification facilities and sewage treatment facilities, activated carbon is used to adsorb organic and inorganic substances to be treated to purify water.

  When activated carbon used for such water purification treatment adsorbs a certain amount of organic matter or inorganic matter, its adsorption performance decreases.

  Here, in recent years, water to be treated has become more sophisticated in water purification facilities and sewage treatment facilities, and the demand for activated carbon has been increasing.

  Therefore, there is concern that it will be difficult to procure stable activated carbon in the future, and a technique for regenerating activated carbon with reduced adsorption performance is being studied.

  As a method for regenerating this type of activated carbon, 80 to 120 ° C. heated air or water vapor is passed through the activated carbon to remove mold smell, and then 130 to 200 ° C. heated air or water vapor is passed through the activated carbon to trihalomethane. There is known a method of removing activated carbon to regenerate activated carbon (for example, see Patent Document 1).

  Moreover, after adding water to the activated carbon which adsorb | sucked the organic chlorine compound, the method of decomposing | disassembling and detoxifying the organic chlorine compound adsorbed to activated carbon by irradiating with ionizing radiation is known (for example, , See Patent Document 2).

  Furthermore, a method is known in which activated carbon used for decolorization of glycine is treated with an alkaline aqueous solution and then washed with water to regenerate the activated carbon (see, for example, Patent Document 3).

  Further, a method is known in which used activated carbon is subjected to arc discharge treatment to remove the adsorbed material adsorbed on the activated carbon and continuously regenerate it (see, for example, Patent Document 4).

  Furthermore, a method is known in which activated carbon is heated with heated steam, and the adsorbed material detached from the activated carbon by this heating is carried out to regenerate the activated carbon (see, for example, Patent Document 5).

  In addition, a method is known in which activated carbon is regenerated by irradiating the used activated carbon with an electron beam to recover the adsorption performance of the activated carbon (see, for example, Patent Document 6).

  Furthermore, there is known a method of regenerating activated carbon by evaporating the organic solvent by causing a current to flow through the used activated carbon containing the organic solvent to generate heat (for example, see Patent Document 7).

  Further, in the method of regenerating activated carbon of the activated carbon filtration tower that adsorbs impurities in the raw water, the activated carbon is heated together with the treated water in a state where the treated water is filled in the filtration tower, and after the treated water is discharged, the filtration is performed. A method is known in which the inside of the tower is evacuated and the adsorbed material is separated from the activated carbon to regenerate the activated carbon (see, for example, Patent Document 8).

  Furthermore, activated carbon as an adsorbing material that adsorbs the pollutants is heated to release the pollutants, and the pollutants separated from the activated carbon and functional water containing components that cause decomposition of the pollutants under light irradiation are irradiated with light. A method for regenerating activated carbon by contacting and decomposing under irradiation is known. In addition, hydrochloric acid, hydrofluoric acid, oxalic acid, sulfuric acid, phosphoric acid, boric acid, etc. are known as such functional water (for example, refer patent document 9).

  Moreover, after removing low boiling point substances by injecting superheated steam at 150 to 250 ° C. onto activated carbon that has adsorbed harmful gas, activated carbon is removed by injecting superheated steam at 300 to 350 ° C. to remove high boiling point substances. A method of reproducing is known (for example, see Patent Document 10).

Japanese Patent Laid-Open No. 5-24815 JP-A-5-49927 JP-A-5-49928 JP-A-5-154378 JP-A-5-154379 Japanese Patent Laid-Open No. 5-293373 Japanese Patent Laid-Open No. 7-256098 Japanese Patent Laid-Open No. 10-109085 JP 2000-167392 A Japanese Patent Laid-Open No. 2004-351312

  However, in the above-described regeneration methods of activated carbon, removal of ignition residues such as aluminum hydroxide and calcium sulfate has not been studied. For this reason, for example, when regenerating activated carbon used in an environment where ignitable residues are likely to adhere, such as an environment where coagulation sedimentation means exist upstream of the water treatment process or an environment where microorganisms are likely to adhere to activated carbon. The ignition residue cannot be sufficiently removed, and the regeneration of the adsorption performance is hindered by the ignition residue, and the adsorption performance of the activated carbon cannot be efficiently recovered.

  This invention is made | formed in view of such a point, and it aims at providing the regeneration method of the activated carbon which can remove an ignition residue and can reproduce | regenerate the adsorption | suction performance of activated carbon efficiently.

  The method for regenerating activated carbon according to claim 1 is a method for regenerating activated carbon used for water treatment to regenerate the adsorption performance of activated carbon to which at least one of an organic substance and an inorganic substance adheres, wherein the activated carbon is an acid solution. The acid-washed activated carbon is heat-treated with a heating means.

  The activated carbon regeneration method described in claim 2 is the activated carbon regeneration method according to claim 1, wherein the acid solution is any one of a hydrochloric acid solution, a sulfuric acid solution, and a phosphoric acid solution.

  The method for regenerating activated carbon according to claim 3 is the method for regenerating activated carbon according to claim 1 or 2, wherein the acid concentration of the acid solution is 0.1 mol / L or more.

  The activated carbon regeneration method described in claim 4 is the activated carbon regeneration method according to any one of claims 1 to 3, wherein the heating means is a rotary kiln.

  According to the first aspect of the invention, since the heat treatment is performed after the acid cleaning, the ignition residue can be removed in advance by the acid cleaning before the heat treatment, and the adsorption performance of the activated carbon can be efficiently regenerated.

  According to the invention described in claim 2, since the acid solution is any one of a hydrochloric acid solution, a sulfuric acid solution and a phosphoric acid solution, the ignition residue can be removed more reliably.

  According to the invention described in claim 3, since the acid concentration of the acid solution is 0.1 mol / L or more, the ignition residue can be efficiently removed.

  According to the invention described in claim 4, since the heating means is a rotary kiln, the activated carbon can be efficiently heated, and the adsorption performance of the activated carbon can be efficiently regenerated.

  Hereinafter, a method for regenerating activated carbon according to an embodiment of the present invention will be described in detail.

  The used activated carbon used for water treatment in water treatment facilities such as water purification facilities and sewage treatment facilities is adhering to organic and inorganic substances, resulting in reduced adsorption performance.

  When regenerating the adsorption performance of activated carbon that has been used for water treatment and has reduced adsorption performance, the activated carbon is acid washed with an acid solution, and the acid-washed activated carbon is heated with a heating means. Remove the kimono.

  Examples of organic substances attached to used activated carbon used in water treatment include, for example, geosmin, 2-methylisoborneol (2-MIB), organic halogen compounds including trihalomethane, and organic halogen precursors (halogens such as chlorine). And substances such as humic acid and fulvic acid that produce trihalomethane by reaction with), anionic surfactants, phenols, trichlorethylene, and products such as aldehydes by ozone reaction.

  Among these organic substances, those specified as water quality criteria are to be removed when the adsorption performance of activated carbon is regenerated. For example, geosmin, 2-methylisoborneol (2-MIB), trihalomethane, negative Ionic surfactants, phenols, trichlorethylene, etc. are included in the water quality standards for tap water.

  Moreover, as an inorganic substance adhering to the used activated carbon used for water treatment, these compounds can be considered, for example, calcium, aluminum, silicon, sulfur, magnesium, iron, phosphorus, strontium, zinc, sodium, and the like.

  Among these inorganic substances, those specified as water quality criteria are to be removed when regenerating the adsorption performance of activated carbon. For example, calcium, aluminum, magnesium, iron, zinc and sodium are tap water. It is included in the water quality standard items, and phosphorus is specified as a drainage standard item.

  In the acid cleaning, the whole activated carbon is immersed in an acid solution and left to stand with stirring for a predetermined time. When the activated carbon is stirred in an acid solution and allowed to stand, an ignition residue such as aluminum hydroxide and calcium sulfate derived from the aggregating agent reacts with the acid solution and leaves the activated carbon. Thereafter, the activated carbon is taken out from the acid solution by filtration using filter paper or the like, and the taken out activated carbon is washed with water and dried.

  The acid solution is preferably a hydrochloric acid solution, a sulfuric acid solution, a phosphoric acid solution, or the like. Further, the acid solution is preferably at least 0.1 mol / L, more preferably at least 1 mol / L because the reaction with the ignition residue hardly proceeds when the acid concentration is lower than 0.1 mol / L. .

  In the heat treatment, the activated carbon after acid cleaning is heated using a heating means. By heating the activated carbon, the adsorbed performance of the activated carbon is regenerated by removing adhering substances such as volatile components that cannot be removed by acid cleaning.

  In the heat treatment, a rotary kiln, a heater, or the like is used as a heating means.

  Furthermore, in the heat treatment, if the heating temperature is lower than 500 ° C., deposits such as volatile components are difficult to remove, and if the heating temperature is higher than 1000 ° C., the activated carbon may be lost or damaged. It is preferably at least 1000 ° C.

  In the heat treatment, it is only necessary that the activated carbon can be heated so that deposits such as volatile components that have entered the activated carbon are removed. For example, when the rotary kiln is used as the heating means, the heating time is 2 hours or more 4 It is preferable that it is in the range of time or less.

  Next, the operation and effect of the one embodiment will be described.

  According to the method for regenerating activated carbon, since the heat treatment is performed after the acid cleaning, an ignition residue that is an organic substance or an inorganic substance attached to the activated carbon can be removed in advance by acid cleaning. Further, since the activated carbon is heat-treated in such a state that the ignition residue is removed, the deposit removal action by the heat treatment is not hindered by the ignition residue, and it is easy to remove even the deposit inside the activated carbon. . Therefore, the adsorption performance of the used activated carbon can be efficiently regenerated.

  By using any one of hydrochloric acid solution, sulfuric acid solution, and phosphorous solution, the acid solution easily reacts with the ignitable residue that is an organic or inorganic substance adhering to the outer surface of the activated carbon. It can be removed more reliably.

  In addition, since the acid solution has an acid concentration of 0.1 mol / L or more, the reaction between the acid solution and the ignition residue tends to proceed, so that the ignition residue can be efficiently removed.

  When the heating means is a rotary kiln, the activated carbon can be efficiently heated, so that the deposits can be easily removed, and the adsorption performance of the activated carbon can be efficiently regenerated.

  Moreover, the heating means can remove deposits reliably and prevent loss or damage of activated carbon due to heating when the heating temperature is 500 ° C. or higher and 1000 ° C. or lower.

  Hereinafter, this example and a comparative example will be described.

  Using the used activated carbon samples A, B, and C, which were used in a water treatment facility and the adsorption performance decreased, a regeneration test of the activated carbon adsorption performance was performed.

  Sample A, Sample B, and Sample C were acid washed and then heat-treated as Example 1.

  Acid cleaning was performed in a laboratory, and 1 L of a 1 mol / L hydrochloric acid solution was added to 250 g of each of Sample A, Sample B, and Sample C, and stirred for 1 hour. Then, no. Suction filtration was performed using 5C filter paper (manufactured by Advantech), and the activated carbon which was the residue after filtration was washed with water.

  In the heat treatment, Sample A, Sample B, and Sample C after washing with water were placed in a crucible and heated at 800 ° C.

  Sample A, Sample B, and Sample C were subjected to heat treatment and then subjected to acid cleaning in the same manner as in Example 1 as Comparative Example 1.

  The heat treatment of Comparative Example 1 was performed using a rotary kiln. Sample A was heat-treated at a regeneration temperature of 813 ° C., a screw speed of 9.5 rpm, and a regeneration time of 7 hours 30 minutes. Sample B was heat-treated at a regeneration temperature of 780 ° C., a screw speed of 8.0 rpm, and a regeneration time of 5 hours and 50 minutes. Sample C was heat-treated at a regeneration temperature of 822 ° C., a screw speed of 6.0 rpm, and a regeneration time of 5 hours and 20 minutes.

  Sample A, Sample B, and Sample C were subjected to heat treatment in the same manner as in Comparative Example 1, and then subjected to alkali cleaning as Comparative Example 2.

  The alkali cleaning was performed in a laboratory, and 1 L of a 1 mol / L sodium hydroxide solution was added to 250 g of each of Sample A, Sample B, and Sample C, followed by stirring for 24 hours. In the case of alkali cleaning, since the solution has viscosity and the activated carbon may be accumulated at the bottom of the container, the stirring time was set to 24 hours. Then, no. Suction filtration was performed using 5C filter paper, and the activated carbon that was the residue after filtration was washed with water.

  Sample A, Sample B, and Sample C were subjected to alkali cleaning in the same manner as in Comparative Example 2, and then subjected to heat treatment in the same manner as in Example 1 as Comparative Example 3.

  And adsorption | suction performance was confirmed about each sample of the activated carbon after the regeneration process of Example 1 and each comparative example. Adsorption performance was confirmed by measuring iodine adsorption power and ignition residue based on JWWA (Japan Water Works Association) standard A114 (granular activated carbon for waterworks) and measuring volatile components. In addition, iodine adsorption power, ignition residue, and volatile components were similarly measured for used activated carbon with reduced adsorption performance as a comparison target for adsorption performance regeneration.

  Here, iodine adsorption power (mg / g) is the amount of iodine that can be adsorbed on 1 g of activated carbon. This iodine adsorption power is obtained by adding each sample of activated carbon stepwise to a 0.05 mol / L iodine adsorption solution, shaking for 15 minutes, measuring the residual iodine concentration, and creating an adsorption isotherm. Is a value of iodine adsorption amount per activated carbon unit that becomes 2.5 g / L.

  The ignition residue is obtained by heating each sample of the activated carbon after the regeneration treatment in an electric furnace to ash the deposits remaining on the activated carbon after the regeneration treatment. That is, the value of the ignition residue (%) indicates the mass of ash remaining after heating with respect to the mass of activated carbon before heating.

  The volatile component is obtained by heating each sample of activated carbon after the regeneration treatment in an electric furnace to volatilize the deposits remaining on the activated carbon after the regeneration treatment. That is, the value of the volatile component (%) indicates the mass of activated carbon reduced after heating (the mass of deposits volatilized by heating) relative to the mass of activated carbon before heating.

  Table 1 shows the measurement results of the ignition residue, Table 2 shows the measurement results of the volatile components, and Table 3 shows the measurement results of the iodine adsorption power.

  As shown in Table 1, compared with the used activated carbon, Example 1 and Comparative Example 1 had a small value of the ignition residue, and the ignition residue was removed by the regeneration treatment. In particular, in Example 1, the ignition residue was stably removed.

  From these results, it is understood that the ignition residue can remove the ignition residue, but the alkali cleaning hardly removes the ignition residue.

  As shown in Table 2, when compared with the used activated carbon, Example 1 and Comparative Example 3 had a small value of the volatile component, and the volatile component was removed by the regeneration treatment. In particular, in Example 1, many volatile components were removed.

  From these results, it is possible to efficiently remove volatile components by heat treatment by acid washing prior to heat treatment and removing the ignition residue, but heat treatment without removing the ignition residue. It can be seen that volatile components are difficult to remove even if

  As shown in Table 3, compared with the used activated carbon, Example 1 had the most regenerated iodine adsorption power.

  From these results, it is possible to remove the ignition residue from the activated carbon by acid cleaning of the used activated carbon. By heating the activated carbon after this acid cleaning, the volatile components are easily removed, and the iodine adsorption power is efficiently improved. You can see that it can be played.

  Therefore, the adsorption performance of the activated carbon can be efficiently regenerated by heat treating the used activated carbon after acid cleaning.

Claims (4)

An activated carbon regeneration method for regenerating the adsorption performance of activated carbon to which at least one of an organic substance and an inorganic substance used for water treatment is attached,
The activated carbon is acid washed with an acid solution,
A method for regenerating activated carbon, comprising heat-treating the acid-washed activated carbon with a heating means. The method for regenerating activated carbon according to claim 1, wherein the acid solution is any one of a hydrochloric acid solution, a sulfuric acid solution, and a phosphoric acid solution. The method for regenerating activated carbon according to claim 1 or 2, wherein the acid concentration of the acid solution is 0.1 mol / L or more. The method for regenerating activated carbon according to any one of claims 1 to 3, wherein the heating means is a rotary kiln.