JP2011031228A - Method and apparatus for removing dissolved sulfide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing dissolved sulfide and an apparatus therefor by which dissolved sulfide can be removed directly and efficiently from water (raw water) such as wastewater. <P>SOLUTION: The apparatus A is composed of: an apparatus body 1 equipped with an activated carbon layer 6 in a treatment tank 5; a raw water supply means 2 by which the raw water W with dissolved sulfide is supplied and allowed to flow through the activated carbon layer 6; and a gas supply means 3 by which gas S containing oxygen is supplied into the treatment tank 5 and allowed to flow through the activated carbon layer 6. Then, the raw water W and the gas S are allowed to flow simultaneously through the activated carbon layer 6, thereby oxidizing the dissolved sulfide by utilizing catalysis of the activated carbon, and converting it to sulfur for removal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dissolved sulfide removal method and a dissolved sulfide removal apparatus for removing sulfides dissolved in water.

When water is dissolved with molecular sulfides such as hydrogen sulfide (H ₂ S) and ionic sulfides such as hydrosulfide ions (HS ⁻ ) and sulfide ions (S ²⁻ ), Volatilization may cause odor, concrete corrosion and metal corrosion. For this reason, food processing factories, sewage treatment plants, human waste treatment plants, and the like take measures to remove this kind of dissolved sulfide from wastewater and the like and to remove volatilized hydrogen sulfide from the gas phase.

  Conventionally, as a countermeasure for removing dissolved sulfide from treated raw water such as wastewater, the dissolved sulfide is forcibly volatilized by aeration of the pH-adjusted raw water, and vaporized sulfide (hydrogen sulfide) ) Are adsorbed and removed with activated carbon, or trapped and removed with a desulfurizing agent.

  Further, as a method for removing the volatilized hydrogen sulfide from the gas phase, Patent Document 1 discloses a method using activated carbon as a catalyst in addition to a method of adsorbing and removing with activated carbon and a method of capturing and removing with a desulfurizing agent. In the method disclosed in Patent Document 1, malodorous gas containing hydrogen sulfide is circulated in the washing tower while jetting the alkaline aqueous solution from the spray provided in the upper part of the washing tower, and the aqueous hydrogen solution absorbs the hydrogen sulfide. Then, activated carbon is added to an aqueous alkaline solution containing hydrogen sulfide and aerated, and aerated, and aerated, and the oxidized sulfide is oxidized by air using the catalytic action of activated carbon to convert dissolved sulfide to sulfur (single sulfur, colloidal sulfur). ). Thus, since the dissolved sulfide can be oxidized to chemically stable sulfur without being converted again to hydrogen sulfide by the catalytic action of activated carbon, the treated water can be discharged as it is.

Japanese Examined Patent Publication No. 62-4167

  However, in the above method for removing dissolved sulfide from the treated raw water, since aeration is performed to volatilize hydrogen sulfide in the gas phase, the amount of air is much larger than the amount of the treated raw water. Thereby, there existed a problem that the scale of the whole apparatus (dissolved sulfide removal apparatus) which combined the aeration tank and the desulfurization apparatus with respect to the processing amount became large.

  In addition, it requires two steps: volatilization of dissolved sulfide from the raw water treated by aeration (volatilization process) and removal of hydrogen sulfide (vaporized sulfide) from the gas phase (removal process). There is a strong demand for a technique that is inefficient and directly removes the dissolved sulfide from the treated raw water. In addition, it is possible to add activated carbon to the treated raw water and directly adsorb and remove the dissolved sulfide, but there is a limit to the amount of activated carbon adsorbed, and the higher the dissolved sulfide concentration, the greater the treatment efficiency. It is not practical because it causes problems in terms of economy.

  On the other hand, using the method disclosed in Patent Document 1, it is also conceivable that the dissolved sulfide is directly removed from the treated raw water by oxidizing the dissolved sulfide to sulfur by the catalytic action of activated carbon. However, even in this method, the activated carbon added to the treated raw water is accelerated by aeration to promote the oxidation reaction of the dissolved sulfide, so that the amount of air is still much larger than the treated raw water. As a result, the scale of the entire processing apparatus becomes large.

  In view of the above circumstances, the present invention aims to provide a dissolved sulfide removal method and a dissolved sulfide removal apparatus capable of directly and efficiently removing dissolved sulfide from raw water such as waste water. To do.

  In order to achieve the above object, the present invention provides the following means.

  The method for removing dissolved sulfide of the present invention is a method for removing dissolved sulfide from raw water in which sulfide is dissolved, and is characterized in that a gas containing oxygen is circulated through the activated carbon layer together with the raw water.

  Further, the dissolved sulfide removing apparatus of the present invention is a dissolved sulfide removing apparatus for removing dissolved sulfide from raw water in which sulfide is dissolved, and an apparatus main body comprising an activated carbon layer in a treatment tank And raw water supply means for supplying the raw water into the treatment tank and flowing it through the activated carbon layer, supplying a gas containing oxygen into the treatment tank and circulating the gas through the activated carbon layer together with the raw water And a gas supply means.

  In these inventions, by circulating raw water such as waste water containing dissolved sulfide and gas containing oxygen through the activated carbon layer, the activated sulfide acts as a catalyst instead of simply adsorbing the dissolved sulfide to the activated carbon. The dissolved sulfide in the water is oxidized by oxygen in the gas, so that the dissolved sulfide can be converted to sulfur. This makes it possible to obtain treated water having a reduced concentration of dissolved sulfide only by circulating a gas containing oxygen together with raw water containing dissolved sulfide to the activated carbon layer.

  In the method for removing dissolved sulfide of the present invention, it is desirable that the gas is circulated through the activated carbon layer together with the raw water in a state where the gas is dispersed in the raw water as fine bubbles.

  Further, in the dissolved sulfide removal apparatus of the present invention, the gas supply means is a fine unit for circulating the gas through the activated carbon layer together with the raw water in a state where the gas is dispersed in the raw water as fine bubbles. It is desirable to have a bubble generator.

  In these inventions, for example, using a microbubble generator such as a microbubble generator or a nanobubble generator, the gas is dispersed in the raw water as microbubbles (for example, microbubbles of about several μm to several tens of μm). And in this state, by circulating the gas along with the raw water to the activated carbon layer, the residence time of the gas (fine bubbles) in the raw water can be remarkably lengthened, so that the gas flows through the activated carbon layer at an early stage relative to the raw water. There is no such thing. Thereby, it becomes possible to exhibit the catalytic action of activated carbon reliably using oxygen contained in the gas. Therefore, the oxidation reaction can be promoted to reliably convert the dissolved sulfide in the raw water into sulfur, and treated water with a reduced concentration of dissolved sulfide can be obtained with certainty.

  According to the method for removing dissolved sulfide and the apparatus for removing dissolved sulfide of the present invention, the raw water containing dissolved sulfide and the gas containing oxygen are circulated through the activated carbon layer, thereby oxidizing the dissolved sulfide in the raw water. Promoted by oxygen in the gas, it is possible to convert the dissolved sulfide to sulfur. This makes it possible to obtain treated water having a reduced concentration of dissolved sulfide only by circulating a gas containing oxygen together with raw water containing dissolved sulfide to the activated carbon layer.

  And compared with the case where dissolved sulfide is removed by aeration as in the past, it is possible to directly remove dissolved sulfide in raw water, and the supply amount of gas containing oxygen is greatly increased. It becomes possible to reduce. For this reason, it becomes possible to perform processing efficiently by greatly reducing the scale of the entire apparatus.

  Moreover, since the catalytic action is used instead of the adsorption action of the activated carbon, the dissolved sulfide does not break through. Furthermore, even if sulfur generated by the oxidation reaction is clogged in the activated carbon layer, it is possible to wash and remove sulfur in the activated carbon layer by performing backwashing or aeration washing in the same manner as a sand filtration device, for example. The performance of the activated carbon as a catalyst can be easily recovered (regenerated). Therefore, it is possible to improve the processing efficiency from this point.

It is a figure which shows the removal apparatus (and removal method of dissolved sulfide: removal apparatus and removal method of case 3 of a verification test) which concerns on one Embodiment of this invention. It is a figure which shows the removal apparatus (The removal apparatus and removal method of case 1 of a verification test) comprised including the glass bead layer. It is a figure which shows the removal apparatus (The removal apparatus and removal method of case 2 of a verification test) comprised including the activated carbon layer. It is a figure which shows the result of a verification test. It is a figure which shows the modification of the removal apparatus (and removal method of dissolved sulfide) of the dissolved sulfide which concerns on one Embodiment of this invention.

  Hereinafter, a dissolved sulfide removal method and a dissolved sulfide removal apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 4. The present embodiment relates to a dissolved sulfide removal method and a dissolved sulfide removal apparatus for removing dissolved sulfide from raw water such as waste water in which sulfide is dissolved by the catalytic action of activated carbon.

  As shown in FIG. 1, the dissolved sulfide removal apparatus A according to the present embodiment includes an apparatus main body 1, raw water supply means 2, and gas supply means 3.

  In the present embodiment, the apparatus main body 1 is formed by including an activated carbon layer 6 formed by layering granular activated carbon in a treatment tank 5 such as a column, and the axis O1 direction (raw water flow direction) is in the vertical direction. It is arranged. Further, the apparatus main body 1 is formed by closing the upper end and the lower end of the processing tank 5 and providing the activated carbon layer 6 on the central side in the direction of the axis O1 in the processing tank 5. Thereby, the space | gap 5a, 5b is each provided and formed in the axis line O1 direction upper end part side and lower end part side across the activated carbon layer 6 in the processing tank 5. Further, a substantially T-shaped discharge pipe 7 is attached to the upper end portion side of the processing tank 5, and this discharge pipe 7 has one end connected to the upper space 5a and the gas discharge port 7a on the other end side. Are disposed so that the treated water discharge port 7b is disposed below.

  The raw water supply means 2 includes a water feed pump 2b connected to the lower end of the treatment tank 5 through a water supply pipe 2a. That is, the raw water supply means 2 of the present embodiment drives the water pump 2b, so that the raw water W is stored in the empty space 5b below the treatment tank 5 from the raw water tank 2c storing the raw water W in which sulfides such as drainage are dissolved. And the raw water W is circulated through the activated carbon layer 6 from below to above.

  The gas supply means 3 includes an air supply pump 3b connected to the lower end portion of the processing tank 5 through an air supply pipe 3a. That is, the gas supply means 3 of the present embodiment supplies air (gas containing oxygen) S to the space 5b below the processing tank 5 by driving the air supply pump 3b, and this air S is used as the activated carbon layer. 6 is configured to circulate from below to above.

  When the dissolved sulfide is removed from the raw water W using the dissolved sulfide removing apparatus A having the above-described configuration, the water supply pump 2b of the raw water supply means 2 and the air supply pump 3b of the gas supply means 3 are driven. Then, the raw water W and the air S are circulated simultaneously through the activated carbon layer 6 of the apparatus main body 1 (the air S is circulated together with the raw water W). At this time, for example, the air S is circulated so as to be about the same amount as the amount of the raw water W.

When the raw water W and the air S are circulated through the activated carbon layer 6 in this way, the dissolved sulfide in the raw water W is not adsorbed by the activated carbon, but the activated carbon acts as a catalyst, and the dissolved sulfide is oxygen in the air S. Oxidized by. As a result, the molecular sulfide (H ₂ S) can be converted into hydrosulfide ions (HS ⁻ ) and sulfide ions (HS 2) and sulfide ions (HS ₂ ) by oxidation reaction only by circulating the air S through the activated carbon layer 6 together with the raw water W containing dissolved sulfide. It is converted into an ionic sulfide of S ²⁻ ), and the ionic sulfide (HS ⁻ , S ²⁻ ) is further converted into chemically stable simple substance and / or colloidal sulfur by an oxidation reaction. Thereby, the treated water W ′ from which the dissolved sulfide is removed is obtained. The treated water W ′ can be easily recovered and removed as sulfur by appropriately filtering the treated water W ′, and clean treated water W ′ from which the dissolved sulfide has been removed can be obtained.

  Here, the demonstration test which confirmed the superiority of the method for removing dissolved sulfide (and the device for removing dissolved sulfide A) according to the present invention will be described.

  First, as shown in FIG. 2, this demonstration test includes a removal device 10 (case 1 (FIG. 2)) including a glass bead layer 8 formed by filling glass beads in a column (treatment tank 5), As shown in FIG. 1 and FIG. 3, the removal apparatus A, 20 (case 2 (FIG. 3), case 3 (FIG. 1)) having an activated carbon layer 6 in the column 5 is used.

  In case 1, as shown in FIG. 2, air (a gas containing oxygen) S is circulated through the glass bead layer 8 together with the raw water W. In case 2, the raw water W is passed through the activated carbon layer 6 as shown in FIG. In case 3, as shown in FIG. 1, air S is circulated through the activated carbon layer 6 together with the raw water W. That is, in Case 1, the removal performance of dissolved sulfide when air S is circulated in addition to the raw water W is confirmed, in Case 2, the removal performance by the activated carbon layer 6 is confirmed, and in Case 3, activated carbon is confirmed. The removal performance (that is, the effect of the present invention) when raw water W and air S are simultaneously passed through the layer 6 is confirmed. In this demonstration test, the superiority of the method for removing dissolved sulfide and the device for removing dissolved sulfide according to the present invention is confirmed by comparing the removal performance of these cases 1, 2, and 3. Yes.

The raw water W was made to have a dissolved sulfide concentration of about 90 mg / L using sodium sulfide (Na ₂ S). Further, the pH was adjusted to 7.0 using hydrochloric acid (HCl). In this demonstration experiment, the raw water W is circulated so that the treatment speed (circulation speed) of the raw water W is about 10 mL / min and the SV (space velocity) is 5. Further, in case 1 and case 3 in which the air S is circulated, the air S is circulated at a circulation speed of about 10 mL / min in accordance with the raw water W.

  FIG. 4 shows the result of measuring the dissolved sulfide concentration of the treated water W ′ of each case sequentially discharged from the treated water discharge port 7 b of the discharge pipe 7 using the detection tube. And from this figure, in the case 1 in which the air S is circulated through the glass bead layer 8 together with the raw water W, the dissolved sulfide concentration of the treated water W ′ becomes almost the same as that of the raw water W. It was confirmed that the dissolved sulfide removal performance is not exhibited only by the circulation.

  In case 2 where only the raw water W was circulated through the activated carbon layer 6, the dissolved sulfide was removed by the adsorption action of the activated carbon at the beginning of the test, but the activated carbon adsorption capacity (adsorption amount) after 20 hours had passed. Reached the limit and a breakthrough in which the concentration of dissolved sulfides suddenly increased was confirmed.

  On the other hand, in case 3 in which the air S was circulated along with the raw water W through the activated carbon layer 6, a slight amount of dissolved sulfide was detected after 30 hours, but a significant increase in concentration was confirmed even after 70 hours. Therefore, it was confirmed that the performance of removing dissolved sulfides was exhibited well.

  In addition, the treated water W ′ in Case 2 was colorless and transparent, whereas the treated water W ′ in Case 3 was suspended in a yellowish white color. Then, the same amount of treated water W 'in Case 2 and Case 3 was collected, filtered through a glass filter and dried, and the substance trapped on the surface of the glass filter was analyzed by fluorescent X-ray analysis. As a result, as shown in Table 1, when a large amount of sulfur is detected in case 3 with respect to case 2 and air S is circulated through activated carbon layer 6 together with raw water W, the catalytic action of activated carbon is exerted, and the raw water is oxidized. It was confirmed that the dissolved sulfide in W was converted to chemically stable sulfur. In all cases, the sulfate ion concentration of the treated water W ′ is measured, but no sulfate ion is detected.

  From the above results, air (gas containing oxygen) S is circulated through the activated carbon layer 6 together with the raw water W in which sulfides are dissolved, so that the catalytic action of the activated carbon is exhibited and the dissolved sulfides are suitably removed from the raw water W. It was confirmed that this was possible, and the superiority of the dissolved sulfide removal method and dissolved sulfide removal apparatus A according to the present invention was demonstrated.

  Therefore, in the dissolved sulfide removal method and the dissolved sulfide removal apparatus A of the present embodiment, the raw water W containing dissolved sulfide and the gas (air S) containing oxygen are simply circulated through the activated carbon layer 6. Rather than adsorbing the dissolved sulfide on the activated carbon, the activated carbon acts as a catalyst, and the dissolved sulfide in the raw water W is oxidized by the oxygen in the gas S, so that the dissolved sulfide can be converted to sulfur. . As a result, it is possible to obtain treated water W ′ having a reduced concentration of dissolved sulfide only by circulating the gas S containing oxygen together with the raw water W containing dissolved sulfide to the activated carbon layer 6.

  And compared with the case where the aeration is performed and the dissolved sulfide is removed as in the prior art, the dissolved sulfide in the raw water W can be directly removed, and the supply amount of the gas S containing oxygen can be reduced. It can be greatly reduced. For this reason, it becomes possible to perform processing efficiently by greatly reducing the scale of the entire apparatus.

  In addition, since the catalytic action is used instead of the adsorption action of activated carbon, the dissolved sulfide is not broken through, and it is possible to recover and remove the dissolved sulfide as sulfur. Waste costs can be greatly reduced. Furthermore, compared to the case where activated carbon is used as an adsorbent, the life of activated carbon is increased by using it as a catalyst as in this embodiment, so that efficient and economical treatment can be realized also in this respect. Is possible.

  Further, even when sulfur generated by the oxidation reaction is clogged in the activated carbon layer 6, the sulfur in the activated carbon layer 6 can be easily washed and removed by performing backwashing or ventilation washing in the same manner as a sand filtration device, for example. It becomes possible. That is, the performance of the activated carbon as a catalyst can be easily recovered (regenerated). Therefore, also from this point, it is possible to improve the processing efficiency and reduce the cost.

  As mentioned above, although one embodiment of the removal method of dissolved sulfide concerning the present invention and the removal apparatus of dissolved sulfide was described, the present invention is not limited to the above-mentioned embodiment, and in the range which does not deviate from the meaning. It can be changed as appropriate. For example, in this embodiment, although it demonstrated as what distribute | circulates the air S with the raw | natural water W to the activated carbon layer 6, in this invention, the gas S distribute | circulated to the activated carbon layer 6 should just contain oxygen, and raw | natural water W Alternatively, pure oxygen or a gas in which the ratio of oxygen is appropriately adjusted may be used in accordance with the concentration of dissolved sulfide and the performance of activated carbon as a catalyst.

  In this embodiment, the air supply pump 3b of the gas supply means 3 is driven to supply the air S directly to the space 5b below the processing tank 5, but for example as shown in FIG. The gas supply means 3 is provided with a microbubble generator 9 such as a microbubble generator or a nanobubble generator, and the gas S containing oxygen is converted into microbubbles (for example, microbubbles of about several μm to several tens μm) S1. In this state, the gas S may be circulated through the activated carbon layer 6 together with the raw water W. In this case, since the residence time of the gas S (fine bubbles S1) in the raw water W can be remarkably increased, the gas S does not circulate through the activated carbon layer 6 at an early stage with respect to the raw water W. . Thereby, it becomes possible to exhibit the catalytic action of activated carbon reliably using oxygen contained in the gas S. Therefore, the oxidation reaction can be promoted to reliably convert the dissolved sulfide in the raw water W into sulfur, and the treated water W ′ having a reduced concentration of dissolved sulfide can be reliably obtained.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 2 Raw water supply means 2a Water supply pipe 2b Water supply pump 2c Raw water tank 3 Gas supply means 3a Air supply pipe 3b Air supply pump 5 Processing tank (column)
5a Upper space 5b Lower space 6 Activated carbon device 7 Discharge pipe 7a Gas discharge port 7b Treated water discharge port 8 Glass bead layer 9 Fine bubble generator A Dissolved sulfide removal device O1 Axis S of device body Air (oxygen) Containing gas)
S1 Fine bubbles W Raw water (water in which sulfide is dissolved)
W 'treated water

Claims (4)

A method for removing dissolved sulfide from raw water in which sulfide is dissolved,
A method for removing dissolved sulfide, wherein a gas containing oxygen is circulated through the activated carbon layer together with the raw water. In the removal method of the dissolved sulfide of Claim 1,
A method for removing dissolved sulfide, wherein the gas is circulated through the activated carbon layer together with the raw water in a state where the gas is dispersed as fine bubbles in the raw water. A device for removing dissolved sulfide for removing dissolved sulfide from raw water in which sulfide is dissolved,
An apparatus main body comprising an activated carbon layer in a treatment tank, raw water supply means for supplying the raw water into the treatment tank and circulating it through the activated carbon layer, and supplying a gas containing oxygen into the treatment tank. And a gas supply means for causing the gas to flow through the activated carbon layer together with the raw water. The apparatus for removing dissolved sulfide according to claim 3,
The dissolved gas sulfide is characterized in that the gas supply means includes a fine bubble generator for circulating the gas to the activated carbon layer together with the raw water in a state where the gas is dispersed as fine bubbles in the raw water. Object removal device.

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