JP6012075B2 - Selenium removal apparatus and removal method - Google Patents

Description

  The present invention relates to an apparatus and a method for removing selenium from waste water containing selenium such as filtrate obtained by washing chlorine bypass dust generated in a cement firing step.

  Selenium and selenium compounds are widely used in the production of various industrial products such as glass products, semiconductor materials, solar cells, movie films, infrared polarizers, pigments, sensitizers, dehydrogenating agents, foaming agents, and the like. .

  However, selenium-containing wastewater containing dissolved selenium is inevitably discharged from manufacturing factories of industrial products using such selenium and selenium compounds, and flue gas desulfurization wastewater from copper-fired power plants and wastewater from copper refineries. Oil refinery wastewater, etc., may contain selenium, which may cause environmental pollution. Therefore, selenium is regulated, and the uniform drainage standard for selenium based on the Water Pollution Control Law is set to 0.1 mg / L.

Therefore, for example, when desalinating chlorine bypass dust collected by a chlorine bypass system attached to a cement production facility, the selenium concentration in the waste water is set to be equal to or lower than a safe standard, as described in Patent Document 1. In the selenium removal method, waste water is passed through an ion exchange resin, and SO ₄ and selenium are simultaneously separated from the waste water.

  Patent Document 2 discloses that after adjusting the pH of the flotation wastewater generated when the slurry containing chlorine bypass dust is subjected to flotation, heavy metals and selenium contained in the wastewater are precipitated, and fluorine is further precipitated. A wastewater treatment method is described in which solid content in the slurry is removed by a solid-liquid separator, and heavy metals and selenium are adsorbed and removed by a chelate resin tower.

JP 2011-189300 A JP 2010-240587 A

  However, in the above prior art, heavy metal ions and coexisting salts present in the wastewater hinder the adsorption of selenium by the resin and significantly reduce the life of the resin, so that it has not been put into practical use.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and an object of the present invention is to use selenium for adsorption of selenium and to remove selenium from waste water or the like at low cost.

To achieve the above object, the present invention provides a selenium removal SaSo location, cement burning step wastewater produced upon washing chlorine bypass dust generated in, or selenium or manufacturing plant of industrial products using the selenium compound Sulfide method in which wastewater to which no chemical is added is introduced and a sulfiding agent is added to the introduced wastewater to insolubilize heavy metals contained in the wastewater as sulfide A reaction tank, a barium salt reaction tank for adding barium salt to the wastewater discharged from the sulfide method reaction tank to insolubilize sulfate ions, selenate ions and selenite ions contained in the wastewater, and the barium salt And a solid-liquid separator that separates the waste water discharged from the reaction tank.

  According to the present invention, various heavy metal ions in the wastewater are precipitated as sulfides by adding a sulfurizing agent, and sulfate ions are insolubilized by adding barium salt, and the treatment liquid obtained by these operations is solidified. By separating the liquid, main adsorption-inhibiting factors can be removed, the load on the adsorbent in the subsequent selenium adsorption step can be reduced, and the adsorbent can be used for a long time.

  A chemical injection control device that controls the amount of barium salt added to the barium salt reaction tank according to the concentration of sulfate ions contained in the filtrate separated by the solid-liquid separator can be provided. A large amount of barium salt can be added, and it is possible to prevent an increase in cost due to excessive use of barium salt, and there is a sulfate ion that does not insolubilize due to an excessive amount of barium salt added. Inhibiting the adsorption of selenium can be prevented.

In the above selenium removal apparatus, Ru can comprise a selectively adsorbed to resin column selenium remaining in the filtrate separated by the solid-liquid separator. As a result , the selenium remaining in the waste water from which the adsorption inhibiting factors such as sulfate ions have been removed is adsorbed and removed by the resin, so that the resin can be used for a long time, and selenium can be removed at low cost.

  In the selenium removal apparatus, the resin tower can be filled with an ion exchange resin or a chelate resin, and selenium can be efficiently removed using a resin having a high ion exchange capacity.

Further, the present invention provides a selenium removal Sakata method, drug effluent from cement burning step wastewater produced upon washing chlorine bypass dust generated in, or selenium or manufacturing plant of industrial products using the selenium compound as heavy metals contained in the wastewater by adding only sulfurizing agent insolubilized as a sulfide, sulfuric acid ions contained in the drainage by adding only barium salt as an agent to waste water after the addition the sulfiding agent selenate ion And selenite ions are insolubilized, and the waste water after addition of the barium salt is subjected to solid-liquid separation. According to the present invention, by adding a sulfurizing agent, various heavy metal ions in waste water are precipitated as sulfides, and by adding barium salt, sulfate ions and the like are insolubilized. By separating, main adsorption inhibition factors can be removed, the load on the adsorbent in the subsequent selenium adsorption step can be reduced, and the adsorbent can be used for a long time.

In the selenium removal Sakata method, it is possible to use water sulfate of sodium as the sulfurizing agent, it is possible to sulfide the more efficient drainage.

Further, the amount of the barium salt to be added can be 0.5 to 5 times the molar amount of the sulfate ion in the waste water after the addition of the sulfurizing agent and before the addition of the barium salt. This addition amount can effectively insolubilize sulfate ions and the like.

Furthermore, selective Ru can be adsorbed on the resin selenium remaining in the filtrate separated by the solid-liquid separation. Thereby , selenium can be removed at low cost by adsorbing and removing selenium remaining in the waste water from which the adsorption-inhibiting factors such as sulfate ions have been removed.

  As described above, according to the present invention, selenium can be removed from waste water or the like at low cost.

It is a whole lineblock diagram showing one embodiment of the selenium removal device concerning the present invention.

  Next, although the form for implementing this invention is demonstrated in detail, referring drawings, this invention is not restrict | limited at all by these embodiment.

  FIG. 1 shows an embodiment of a selenium removal apparatus according to the present invention. This selenium removal apparatus 1 includes a drain tank 3 that stores selenium-containing waste water W, and a sulfurization agent that adds a sulfurizing agent S to the selenium-containing waste water W1. A solid-liquid separation of the solid-liquid separation of the physical method reaction tank 4, the barium salt reaction tank 6 for adding barium salt B to the waste water W2 discharged from the sulfide method reaction tank 4, and the waste water W3 discharged from the barium salt reaction tank 6 It comprises a liquid separator 8, a sulfate ion concentration meter 10 that measures the concentration of sulfate ions in the filtrate F 1 separated by the solid-liquid separator 8, and a resin tower 11 that adsorbs selenium remaining in the filtrate F 1. The

The selenium-containing wastewater W1 is, for example, wastewater obtained by solid-liquid separation after reacting the slurry produced when the chlorine bypass dust generated in the cement firing process is washed with water with a gas containing SO ₂ or CO _2. This waste water contains sulfate ions (SO ₄ ^{2 −} ), selenate ions (SeO ₄ ²⁻ ), and selenite ions (SeO ₃ ²⁻ ).

The sulfide method reaction tank 4 is prepared to add a sulfiding agent S such as sodium hydrosulfide (NaSH) to the selenium-containing wastewater W1 discharged from the drainage tank 3 to insolubilize various heavy metal ions in the selenium-containing wastewater W1. It is done. In addition to sodium hydrosulfide, sodium sulfide (Na ₂ S) or the like can be used as the sulfiding agent S.

  The barium salt reaction tank 6 adds barium salts such as barium hydroxide, barium nitrate, barium carbonate, and barium chloride to the wastewater W2 in which heavy metal ions are insolubilized, and sulfate ions, selenate ions, and selenium selenium in the wastewater W2. Provided to insolubilize acid ions. Among the barium salts, it is preferable to use barium chloride from the viewpoints of cost and handling properties.

  The solid-liquid separator 8 is provided to separate the waste water W3 discharged from the barium salt reaction tank 6 into a solid and a liquid, and the waste water W3 is separated into a precipitate D and a filtrate F1.

  The sulfate ion concentration meter 10 is provided for measuring the concentration of sulfate ions in the filtrate F1 separated by the solid-liquid separator 8, and a barium salt according to the sulfate ion concentration measured by the sulfate ion concentration meter 10 is provided. A chemical injection control device (not shown) for controlling the amount of barium salt added to the reaction tank 6 is configured.

  The resin tower 11 is provided to adsorb selenium (selenate ion, selenite ion) remaining in the filtrate F1 that has passed through the sulfate ion concentration meter 10, and the resin includes an ion exchange resin, a chelate resin, and the like. Used.

  Next, a selenium removal method according to the present invention using the selenium removal apparatus 1 will be described with reference to FIG.

  The selenium-containing wastewater W1 stored in the drainage tank 3 is supplied to the sulfide method reaction tank 4, and the sulfide agent S is added in the sulfide method reaction tank 4, so that heavy metals contained in the selenium-containing wastewater W1 are insolubilized as sulfides. .

  Next, the waste water W2 is supplied from the sulfide method reaction tank 4 to the barium salt reaction tank 6, and in the barium salt reaction tank 6, the barium salt B is added to sulfate ions, selenate ions, selenite in the waste water W2. Insolubilizes ions. Here, it is preferable that the amount of the barium salt B to be added is 0.5 to 5 times the molar amount of the sulfate ion concentration.

Table 1 shows changes in the concentrations of selenium and sulfate ions when barium chloride is added to the waste water W2. As shown in the same table, selenium ions (selenate ions in waste water) are added by adding 0.5 times mole amount, 1 times mole amount, and 2 times mole amount of barium chloride to the mole amount of sulfate ions. , it is seen that the concentration of selenite ion) and sulfate ions is substantially reduced. In particular, the rate of decrease when a 1-fold molar amount and a 2-fold molar amount of barium chloride are added is remarkable.

次いで、バリウム塩反応槽６から排出された排水Ｗ３を固液分離機８で固液分離し、上記不溶化によって生じた析出物Ｄと、析出物Ｄが除去されたろ液Ｆ１とに分離する。

Next, the waste water W3 discharged from the barium salt reaction tank 6 is solid-liquid separated by the solid-liquid separator 8 and separated into the precipitate D generated by the insolubilization and the filtrate F1 from which the precipitate D has been removed.

  The concentration of sulfate ion in the filtrate F1 discharged from the solid-liquid separator 8 is measured by a sulfate ion concentration meter 10, and the amount of barium salt B added to the barium salt reaction vessel 6 is controlled according to the measured value. That is, when the measured sulfate ion concentration is higher than a predetermined value, the amount of barium salt B added to the barium salt reaction tank 6 is increased. When the measured sulfate ion concentration is lower than the predetermined value, barium is added. The amount of barium salt B added to the salt reaction tank 6 is decreased.

  Next, the filtrate F1 discharged from the solid-liquid separator 8 is supplied to the resin tower 11 to adsorb selenate ions and selenite ions remaining in the filtrate F1. As described above, since the selenate ion, selenite ion and sulfate ion in the filtrate F1 are greatly reduced by the addition of the barium salt, the selenate ion and selenite ion contained in the filtrate F1. The concentration of is low, the load on the resin tower 11 is reduced, and the adsorption resin can be used for a long time. The filtrate F2 in which selenate ions and selenite ions are adsorbed in the resin tower 11 is discharged out of the system.

  In the above-described embodiment, the configuration including the resin tower 11 that selectively adsorbs the selenium remaining in the filtrate F1 separated by the solid-liquid separator 8 has been described. In this case, the configuration of the drainage tank 3 to the solid-liquid separator 8 shown in FIG. 1 is regarded as a pretreatment device for removing selenium, and various heavy metal ions, sulfate ions, selenate ions, selenite in advance. By insolubilizing the ions and removing them from the waste water, the load on the adsorbent in the adsorption process can be reduced, and the adsorbent can be used for a long time.

Although illustrated wastewater generated when washed with water chlorine bypass dust generated in the cement burning process as selenium-containing wastewater W1, directed to the waste water of a manufacturing plant or these industrial products using other selenium and selenium compounds You can also

DESCRIPTION OF SYMBOLS 1 Selenium removal apparatus 3 Drain tank 4 Sulfide method reaction tank 6 Barium salt reaction tank 8 Solid-liquid separator 10 Sulfate ion concentration meter 11 Resin tower B Barium salt D Precipitate F1, F2 Filtrate S Sulfide W1-W3 (Selenium Contained) drainage

Claims (8)

Cement burning step wastewater produced upon washing chlorine bypass dust generated in, or used selenium or selenium compound be any of wastewater from the production plant for industrial products, wastewater agent has not been added is introduced A sulfide method reaction tank for adding a sulfiding agent to the introduced waste water to insolubilize heavy metals contained in the waste water as sulfides;
A barium salt reaction tank for adding barium salt to the wastewater discharged from the sulfide method reaction tank to insolubilize sulfate ions, selenate ions and selenite ions contained in the wastewater;
Selenium removal SaSo location, characterized in that it comprises a solid-liquid separator for solid-liquid separation has been drained discharged from the barium salt reactor. 2. A chemical injection control device for controlling the amount of barium salt added to the barium salt reaction tank according to the concentration of sulfate ions contained in the filtrate separated by the solid-liquid separator. selenium removal SaSo location described. Selenium removal apparatus according to claim 1 or 2, characterized in that it comprises a resin column to selectively adsorb selenium remaining in the filtrate separated by the solid-liquid separator.   The selenium removing apparatus according to claim 3, wherein the resin tower is filled with an ion exchange resin or a chelate resin. Heavy metals contained in the cement burning step wastewater produced upon washing chlorine bypass dust generated in, or the drainage by adding only sulfurization agent as selenium or agent to the wastewater from the production plant for industrial products using a selenium compound Insolubilized as sulfides,
Add only the barium salt as a chemical to the waste water after the addition of the sulfurizing agent to insolubilize sulfate ion, selenate ion and selenite ion contained in the waste water,
Features and to Rousset Ren removal method that you solid-liquid separating the waste water after addition the barium salt. Selenium removal Sakata method according to claim 5, characterized in that water is used vulcanization of soda as the sulfurizing agent. The amount of the barium salt to be added is 0.5 to 5 times the molar amount of the sulfate ion concentration in the waste water after the addition of the sulfurizing agent and before the addition of the barium salt. selenium removal Sakata method according to claim 5 or 6. Selenium removal method according to claim 5, 6 or 7, characterized in that selectively adsorbed to the resin selenium remaining in the filtrate separated by the solid-liquid separation.

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