JP2008183526A - Method for treating acid waste liquid and alkali waste liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating an acid waste liquid and an alkali waste liquid by which the acid waste liquid and the alkali waste liquid caused in a pickling step, a surface treatment step or the like for a steel sheet can be cleaned into a reusable state as industrial water with a compact equipment configuration. <P>SOLUTION: The method for treating an acid waste liquid and an alkali waste liquid comprises: a neutralization-condensation/precipitation treatment step 10 where an acid waste liquid and an alkali waste liquid are neutralized, and thereafter, condensation/precipitation treatment is performed; and a purification treatment step 20 where the treated water treated by the neutralization-condensation/precipitation treatment step 10 is purified by an ion exchange resin, and further, as the regeneration liquid of the ion exchange resin, an acid waste liquid and an alkali waste liquid are used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for treating acidic waste liquor and alkaline waste liquor generated in a manufacturing process or the like of a steel sheet.

  For example, a large amount of acidic waste liquid and alkaline waste liquid are generated from the pickling process and the surface treatment process of the steel sheet. For this purpose, both waste liquids are discharged after being processed in a waste liquid treatment facility.

  That is, as shown in FIG. 2, the acidic waste liquid received in the acidic waste liquid receiving tank 11 and the alkaline waste liquid received in the alkaline waste liquid receiving tank 12 are introduced into the neutralization tank 13 for neutralization, and the condensed precipitation tank 14 It is discharged after being condensed and settled.

  At that time, the treated water (effluent) treated with the waste liquid treatment equipment as described above has a high concentration of calcium and chlorine, and when recovered and reused, pipe clogging due to a large amount of calcium adhering to the inner surface of the pipe Since corrosion of piping and equipment due to chlorine occurs, it is not suitable for reuse as industrial water.

  On the other hand, when the industrial water is tight, excess water generated in the rolling process, etc. is recovered and reused, but for further recovery and reuse, treatment with the above waste liquid treatment equipment There is no choice but to collect and reuse water. By the way, the additional purchase of industrial water adds a large cost burden.

  Therefore, on the downstream side of the waste liquid treatment facility shown in FIG. 2, a water treatment facility (for example, see Patent Document 1) using an ion exchange resin used in pure water production or the like is installed, and the waste liquid treatment facility shown in FIG. A method of reusing as industrial water by removing calcium and chlorine from the treated water for purification.

  FIG. 3 shows an example of a water treatment facility using an ion exchange resin. The raw water is sent to a cation exchange tower (H tower) 21 filled with a cation exchange resin, and sodium ions and calcium ions present in the raw water. Are exchanged for hydrogen ions by the action of the cation exchange resin and removed. At this time, the carbon dioxide released in the water is removed in the degassing tower 23. Further, water is introduced into an anion exchange tower (OH tower) 22 filled with an anion exchange resin, and sulfate ions, chlorine ions, etc. in the water are exchanged with hydroxide ions and removed by the action of the anion exchange resin. Thereby, unnecessary ions in the raw water are removed and purified.

When the ion exchange function of the ion exchange resin (cation exchange resin, anion exchange resin) approaches a saturated state, a regeneration solution (acid) is supplied from the acid storage tank 24 to the cation exchange tower 21 and ion exchange of the cation exchange resin is performed. The function is regenerated, and a regeneration solution (alkali) is supplied from the alkali storage tank 25 to the anion exchange tower 22 to regenerate the ion exchange function of the anion exchange resin. At that time, the regeneration waste liquid discharged from the cation exchange column 21 contains excess acid, and the regeneration waste liquid discharged from the anion exchange column 22 contains excess alkali. Is neutralized in the neutralization tank 26 and then discharged.
JP-A-11-221561

  However, if the water treatment facility using the ion exchange resin as shown in FIG. 3 is directly installed on the downstream side of the waste liquid treatment facility as shown in FIG. 2, a large installation space and installation costs are required for that purpose. There is a problem.

  The present invention has been made in view of the circumstances as described above, and acidic waste liquid and alkaline waste liquid generated from a pickling process or a surface treatment process of a steel sheet can be reused as industrial water by a compact equipment configuration. It is an object of the present invention to provide a treatment method for acidic waste liquid and alkaline waste liquid that can be purified to a proper state.

  In order to solve the above problems, the present invention has the following features.

  [1] A neutralization / condensation precipitation treatment process in which acid waste liquid and alkaline waste liquid are neutralized and then subjected to condensation precipitation treatment, and treated water treated in the neutralization / condensation precipitation treatment step is purified by an ion exchange resin. And a treatment method for an acidic waste solution and an alkaline waste solution, wherein the acidic waste solution and the alkaline waste solution are used as a regeneration solution for the ion exchange resin.

  [2] Recycled waste liquid of ion exchange resin discharged is returned to the neutralization / condensation precipitation treatment step, mixed with acidic waste liquid and alkaline waste liquid, and then processed. A method for treating acidic and alkaline waste liquids.

  [3] The acidic and alkaline waste liquids according to the above [2], wherein the acidic waste liquid and the alkaline waste liquid mixed with the regenerated waste liquid of the ion exchange resin are neutralized and coagulated, and then discharged as they are. Processing method.

  [4] The degree of purification of water after treatment in the purification treatment step is measured, and when the predetermined purification degree is not obtained, the purification treatment in the purification treatment step is interrupted and the treated water is discharged. The method for treating acidic waste liquid and alkaline waste liquid according to any one of [1] to [3].

  In the present invention, neutralization / condensation precipitation treatment of acid waste liquid and alkaline waste liquid and purification treatment with ion exchange resin are organically combined, so that a storage tank for regenerated liquid of ion exchange resin is not required, and compact. With such an equipment configuration, it is possible to purify acidic waste liquor and alkaline waste liquor generated from the pickling process and surface treatment process of steel sheets into a state that can be reused as industrial water.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a method for treating an acidic waste liquid and an alkaline waste liquid according to an embodiment of the present invention, and neutralizes an acidic waste liquid and an alkaline waste liquid acidic waste liquid generated from a pickling process, a surface treatment process, etc. of a steel sheet. Then, a neutralization / condensation precipitation treatment step 10 for performing condensation precipitation treatment, and a purification treatment step 20 for purifying the treated water treated in the neutralization / condensation precipitation treatment step 10 with an ion exchange resin are provided.

  First, in the neutralization / condensation precipitation treatment step 10, the acidic waste solution and the alkaline waste solution generated from the pickling step and the surface treatment step of the steel sheet are received in the acidic waste solution receiving tank 11 and the alkaline waste solution receiving tank 12, respectively. It introduce | transduces into the neutralization tank 13, is neutralized, it is sent to the condensation precipitation tank 14, and a condensation precipitation process is performed. Then, the treated water is sent to the purification treatment step 20 by the pump 31.

  Next, in the purification treatment step 20, the treated water treated in the neutralization / condensation precipitation treatment step 10 is sent to a cation exchange tower (H tower) 21 filled with a cation exchange resin, and calcium present in the treated water. Ions are exchanged with hydrogen ions and removed by the action of the cation exchange resin. At this time, the carbon dioxide released in the water is removed in the degassing tower 23. Further, water is introduced into an anion exchange tower (OH tower) 22 filled with an anion exchange resin, and chlorine ions in the water are exchanged with hydroxide ions and removed by the action of the anion exchange resin. Thereby, calcium ions and chlorine ions in the water are removed and recovered to be purified to a state where they can be reused as industrial water.

  In this embodiment, when the ion exchange function of the ion exchange resin (cation exchange resin, anion exchange resin) approaches a saturated state, the acidic waste liquid is supplied from the acidic waste liquid receiving tank 11 to the cation exchange tower 21 as a regenerated liquid. Thus, the ion exchange function of the cation exchange resin is regenerated, and the alkaline waste liquid is supplied as a regenerated liquid from the alkaline waste liquid receiving tank 11 to the anion exchange tower 22 to regenerate the ion exchange function of the anion exchange resin.

  Further, a regeneration waste liquid discharged from the cation exchange column 21 in a state containing excess acid and removed calcium, and a regeneration waste liquid discharged from the anion exchange column 22 in a state containing excess alkali and removed chlorine, The process is returned to the neutralization / condensation precipitation processing step 10 for processing. That is, the regenerated waste liquid discharged from the cation exchange tower 21 is mixed with the acidic waste liquid from the acidic waste liquid receiving tank 11 and sent to the neutralization tank 13, and the regenerated waste liquid discharged from the anion exchange tower 22 is received as the alkaline waste liquid. It is mixed with the alkaline waste liquid from the tank 12 and sent to the neutralization tank 13.

  At that time, in order to prevent calcium and chlorine from concentrating, the neutralization and coagulation sedimentation treatment is performed in the neutralization tank 13 and the condensation precipitation tank 14 for the acidic waste liquid and the alkaline waste liquid containing the regeneration waste liquid of the ion exchange resin. Then, the on-off valve 32 on the pump 31 side is closed and the on-off valve 33 on the discharge side is opened, so that it is discharged as it is without being sent to the purification treatment step 20.

  Further, a concentration meter 36 for measuring the calcium concentration and the chlorine concentration is provided on the downstream side of the anion exchange tower 22 so that the calcium concentration and the chlorine concentration of the water after the treatment in the purification treatment step 20 are measured. Yes.

  At this time, if the calcium and chlorine concentrations that can be reused as industrial water are exceeded, the on-off valve 32 is closed, the purification process in the purification treatment step 20 is interrupted, and the discharge-side on-off valve 33 is opened. Then, the treated water that has been treated in the neutralization / condensation precipitation treatment step 10 is discharged as it is, and the treated water that has already been sent to the purification treatment step 20 is closed by closing the recovery-side opening / closing valve 34. The valve 35 is opened and discharged without being collected.

  Then, an acidic waste liquid is supplied from the acidic waste liquid receiving tank 11 to the cation exchange tower 21 as a regenerated liquid, and an alkaline waste liquid is supplied from the alkaline waste liquid receiving tank 11 to the anion exchange tower 22 as a regenerated liquid, so that the ion exchange function of the ion exchange resin is performed. Then, the purification process in the purification process step 20 is resumed.

  As described above, in this embodiment, neutralization / condensation precipitation treatment of acidic waste liquid and alkaline waste liquid and purification treatment by ion exchange resin are organically combined. The acid storage tank 24, the alkali storage tank 25, and the neutralization tank 26 for the regenerated liquid of the exchange resin are not required, and the acidic waste liquid and the alkaline waste liquid generated from the pickling process and the surface treatment process of the steel sheet are reduced by a compact equipment configuration. It can be purified to a reusable state as industrial water.

It is a figure which shows the processing method of the acidic waste liquid and alkaline waste liquid which concern on one Embodiment of this invention. It is a figure which shows the processing method of the conventional acidic waste liquid and alkaline waste liquid. It is a figure which shows an example of the water treatment equipment by an ion exchange resin.

Explanation of symbols

10 Neutralization / Condensation Precipitation Process 11 Acid Waste Liquid Receiving Tank 12 Alkaline Waste Liquid Receiving Tank 13 Neutralization Tank 14 Condensation Precipitation Tank 20 Purification Process 21 Cation Exchange Tower (H Tower)
22 Anion exchange tower (OH tower)
23 Degassing tower 24 Acid storage tank 25 Alkali storage tank 26 Neutralization tank 31 Pump 32, 33 On-off valve 34, 35 On-off valve

Claims (4)

  Neutralization / condensation precipitation process that neutralizes acid waste liquid and alkaline waste liquid and then performs condensation / precipitation treatment, and purification treatment that purifies the treated water treated in the neutralization / condensation precipitation treatment process with an ion exchange resin A method for treating an acidic waste liquid and an alkaline waste liquid, comprising the steps of using the acidic waste liquid and the alkaline waste liquid as a regeneration liquid for the ion exchange resin.   The discharged waste liquid of the ion exchange resin discharged is returned to the neutralization / condensation precipitation treatment step, mixed with the acidic waste liquid and the alkaline waste liquid, and then processed. Waste liquid treatment method.   The method for treating acidic waste liquid and alkaline waste liquid according to claim 2, wherein the acidic waste liquid and the alkaline waste liquid mixed with the regenerated waste liquid of the ion exchange resin are neutralized and coagulated, and then discharged as they are.   The degree of purification of water after treatment in the purification treatment step is measured, and when the predetermined degree of purification is not obtained, the purification treatment in the purification treatment step is interrupted and the treated water is discharged. The processing method of the acidic waste liquid in any one of claim | item 1-3, and an alkaline waste liquid.

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