JP2013006160A - Sulfur oxide removing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desulfurizing agent which allows compactification of a desulfurization apparatus, is easy to be filled in and removed from the desulfurization apparatus, can facilitate the maintenance of the desulfurization apparatus, and has high removal capability of a sulfur oxide.SOLUTION: Water that contains impurities including at least a minute amount of an iron component and a calcium component is treated by iron bacteria to recover sludge, and a gas that contains the sulfur oxide is made to pass through the sludge to remove the sulfur oxide in the gas.

Description

  The present invention relates to a sulfur oxide removing material from a gas such as the atmosphere or flue gas, and a method for removing sulfur oxide from a gas such as the air or flue gas.

  Since flue gas from factories and the like often contains sulfur components and causes air pollution, a method of removing sulfur components in flue gas using a flue gas desulfurization device is usually used. .

  Known methods for flue gas desulfurization include wet methods such as a wet lime method, a wet soda method, and a wet magnesium hydroxide method, and a dry method using an adsorption method using activated coke. In addition, Limonite (dehydrated hydrogen sulfide manufactured by Nihon Limonite Co., Ltd.) mainly composed of iron hydroxide is used for the purpose of making the desulfurization device compact, facilitating the filling and removal of the desulfurization device, and simplifying the maintenance of the desulfurization device A method using an agent: Limonic (registered trademark) has been studied (Patent Document 1).

JP 2009-298980 A

  By the way, since the above-mentioned limonite is a dehydrosulfurizing agent, it is considered that removal of hydrogen sulfide is sufficient, but the removal ability of other sulfur components such as sulfur oxides is not clear.

  Therefore, the present invention provides a desulfurization agent that has a compact desulfurization device, can be easily charged and removed into the desulfurization device, can be easily maintained and managed, and has a high sulfur oxide removal capability. Objective.

  This invention treats water containing impurities containing at least a trace amount of iron components with iron bacteria, and employs an iron bacteria method to recover impurities as sludge. The above-mentioned problem has been solved by removing the sulfur oxide in the gas by allowing the gas containing the oxide to pass therethrough.

  According to the present invention, since sludge generated by the iron bacteria method is used as a sulfur oxide removing material, it is easy to fill and remove the desulfurization apparatus, and the maintenance and management of the desulfurization apparatus is simplified.

  In addition, the iron bacteria method is used in water purification plants that remove impurities from groundwater and other water containing impurities that contain trace amounts of iron and calcium components, but since sludge that has been disposed of in the past can be used, Effective use of waste becomes possible.

  The sulfur oxide removing material according to the present invention is a removing material made of sludge produced by the iron bacteria method.

  The iron bacteria method is an iron bacteria method in water treatment technology, which uses bacteria that oxidize iron in water (generally called “iron bacteria”), and removes impurities such as trace amounts of iron components. This is a water purification method for the purpose of removing these impurities from the water such as groundwater to obtain purified water.

  Examples of the iron bacteria include the genus Leptothrix and the genus Galionella.

  In this iron bacteria method, first, water containing impurities including at least a trace amount of iron components, such as ground water, is brought into contact with a biological contact carrier inhabiting the iron bacteria to oxidize the impurities. Thereby, the oxide of the impurity is suspended in water, and the water and solid content can be separated by a method such as adsorption and filtration.

  The obtained water is used as purified water containing almost no impurities. And solid content is collect | recovered as sludge. This recovered sludge can be used as a sulfur oxide removing material.

  The water supplied to the iron bacteria method is water containing at least an iron component as an impurity, and may further contain a manganese component or the like. Among these impurities, the content of the iron component is generally preferably 1 ppm or more, more preferably 5 ppm or more as the content of the metal portion. If it is less than 1 ppm, iron oxidation by iron bacteria is unlikely to occur, and there may be a problem that sludge containing iron is not generated. On the other hand, the upper limit of the content of the iron component is not particularly limited, and the solubility of the iron component in water is the upper limit.

  Such iron bacteria method is used in several water purification plants in Japan. Such water purification plants include Kita-Koriyama Water Purification Plant in Yamatokoriyama City, Nara Prefecture, Otsubo Water Purification Plant in Tamba City, Hyogo Prefecture, No. 3 Water Purification Plant in Joyo City, Kyoto Prefecture, an experimental facility in the Collection Women's Water Purification Plant in Mukaichi City, Kyoto Prefecture, An experimental facility at Uchimancho Hot Spring Hospital in Ishikawa Prefecture.

  The impurity component contained in the sludge produced by the iron bacteria method varies depending on the impurities contained in the water to be treated, but also contains manganese and the like in addition to iron.

  The content ratio of the iron component contained in the sludge (solid content) is preferably 10% by weight or more, more preferably 25% by weight or more, as the content ratio of the metal portion. If it is less than 10% by weight, there may be a problem that the performance of removing sulfur oxides by iron is lowered. On the other hand, the upper limit of the content of the iron component is not particularly limited, and may be 100%.

  Although this sludge may be used as a sulfur oxide removing material in a water-containing state, when the medium containing the sulfur oxide is a gas such as air, it is easier to pass the dried sludge. Therefore, this is dried and the dried product is packed in a tube such as a column. In this way, when a gas containing sulfur oxide is passed through the tube, the sulfur oxide is adsorbed on the dried product or reacts with components in the dried product when passing through the dried product. Or taken into the dried product. Thereby, the amount of sulfur oxides in the gas that has passed through the dried product can be reduced below the detection limit.

  In addition, using an aqueous solution or water suspension in which an appropriate amount of this sludge (solid content) is dissolved or suspended in water, the atmosphere or flue gas containing sulfur oxides is passed through the aqueous solution or water suspension, or this Sulfur oxide can also be removed by spraying (sprinkling) an aqueous solution or a water suspension on the atmosphere containing sulfur oxide or smoke.

  As a method for detecting sulfur oxide in the gas, a detector tube for sulfur dioxide can be used. As this detector tube, a detector tube having a detection limit of 0.05 ppm can be used. For this reason, in this case, below the detection limit means less than 0.05 ppm.

  In addition, as for the removal ability of sulfur oxide, whether one component in sludge is effective, whether multiple components are synergistically effective, or a trace amount component that is not described above has some effect It is unknown.

Hereinafter, the present invention will be described more specifically using examples.
First, the measurement method will be described.
<Measurement of sulfur dioxide concentration>
From the sample collection valve attached to the sample bag to be measured, the internal gas is changed using a detector tube (manufactured by Gastec Corporation: detector tube for sulfur dioxide: No. 5Lb, detection limit: 0.05 ppm). Aspiration was performed and the sulfur dioxide concentration was measured.
The suction amount of the sampling bag 1 on the side to be supplied to the column is 50 ml, and the suction amount of the sampling bag 2 that collects air after passing through the column is 800 ml.

<EDX measurement>
Sludge was dried and compressed and solidified, and the content of iron and the like was measured using an energy dispersive X-ray fluorescence analyzer (EDX) manufactured by Shimadzu Corporation.

(Examples 1-4)
After collecting and precipitating backwash wastewater at the water purification plant (experimental site) shown in Table 1 below, the sludge that had passed through the 1 mm sieve was precipitated again, and the dried sludge was evaporated and dried in a 40 ° C drying cabinet It grind | pulverized with the mortar, 0.3g was packed into the plastic column (Bio-Rad company) of length 100mm and internal diameter 10mm using this as a sulfur oxide removal material (column height 10mm). The sludge was sandwiched between 10 denier chemical fibers to prevent the sludge from splashing at both ends.
Next, valves were provided at both ends of the column, and 1 L sampling bags (with one Tedlar bag) 1 and 2 were attached to both ends. A three-way valve for sampling was attached between the valves at both ends and the sampling bags 1 and 2.
Next, in order to generate sulfur oxides, an appropriate amount of sodium thiosulfate aqueous solution (0.025 mol / L) is put into a 500 mL beaker, and an appropriate amount of concentrated hydrochloric acid is mixed and stirred, and then the air above the liquid is collected with a plastic syringe. And placed in another sampling bag 3.
The air in the sampling bag 3 in which the sulfur oxide is taken into one sampling bag 1 attached to the column is finally put so that the sulfur oxide concentration in the sampling bag 1 becomes 7.4 to 8.0 ppm, and then Into a sampling bag attached to the column, air was introduced with an air pump until 1 L.
Thereafter, the sampling bag 1 was shrunk by hand, the air in the sampling bag 1 was allowed to flow into the column, and the air was moved to the other sampling bag 2 (the inflow time was about 30 s). After all the air was moved, the sulfur dioxide concentration of the moved air was measured in the same manner. This experiment was repeated three times.
Moreover, in order to measure the iron content in the sludge, EDX measurement was performed.
These results are shown in Tables 1 and 2.

(Comparative Examples 1-2)
A sulfur oxide removal test was performed in the same manner as in Example 1 except that the materials shown in Table 1 were used as the sulfur oxide removing material. Moreover, in order to measure the iron content in the sludge, EDX measurement was performed. These results are shown in Tables 1 and 2.
In addition, the limonite of the comparative example 1 is a limonite which is a raw material of the desulfurization agent “Limonic” (registered trademark) manufactured by Japan Limonite Co., Ltd., which is dried by the same method as in Example 1. Donated to the experiment.
Moreover, the volcanic ash of the comparative example 2 is the volcanic ash of Shinmoedake where the eruption started on January 26, 2011, and is collected from the crater and deposited at a point of 10 km. What was dried in the same manner as in Example 1 was donated to the experiment.

(result)
As is clear from Examples 1 to 4, it became clear that the sludge obtained by the iron bacteria method has the ability to remove sulfur oxides.
On the other hand, from the results of Comparative Example 1, it was found that limonite known as a hydrogen sulfide removing material had a lower sulfur oxide removing ability than the sludge used in Examples 1 to 4.
By the way, limonite is limonite obtained from Mt. Aso. For this reason, volcanic ash may also have some effect. Therefore, in Comparative Example 2, an experiment was performed using volcanic ash. As a result, it was found that although it has a little sulfur oxide removing ability, it is not sufficient.

Claims (2)

  A sulfur oxide removal material consisting of sludge produced by the iron bacteria method. Water containing impurities containing at least a trace amount of iron components is treated with iron bacteria to collect sludge,
A method for removing sulfur oxide from a gas, wherein the sulfur oxide in the gas is removed by passing a gas containing sulfur oxide through the sludge.