JP2011230023A - Biological treatment method and apparatus for waste water containing sulfuric cod component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biological treatment method and apparatus for waste water containing a sulfuric COD component that can restrain the formation of noxious hydrogen sulfide when carrying out biological treatment of waste water containing the sulfuric COD component produced in a factory or the like to turn into sulfate ions (SO) for detoxification.SOLUTION: Traffic of a treatment liquid L is attained at a part of a partition wall 14 of a treatment tank 1 constituting the biological treatment apparatus 100, and pH is adjusted to 8-9 in respective sections with the partition wall 14 held between.

Description

  The present invention relates to biological treatment of wastewater containing sulfur-based COD components generated in factories and the like, for example, biological organisms of wastewater containing sulfur-based COD components, such as leachate that comes into contact with slag, which is generated in steelmaking plants and the like during rain The present invention relates to a processing method and apparatus.

For example, in an iron factory, the blast furnace slag discharged from the blast furnace is mainly composed of CaO and SiO ₂ , but since the inside of the blast furnace has a strong reducing atmosphere, most of the sulfur contained in iron ore and coke is slag. Thus, the slag contains 1-2% by mass of sulfur inside and outside.

  The molten slag discharged from the blast furnace (hereinafter referred to as blast furnace slag) is usually cooled to an appropriate temperature in a cooling field (slag yard), solidified, dug up by a bulldozer, a power shovel, etc., and temporarily placed Later, it is used as civil engineering and building materials such as artificial crushed stone and ground improvement materials.

  If rainwater comes into contact with the blast furnace slag during this cooling or temporary placement, the components in the blast furnace slag are leached into the rainwater. Even when the blast furnace slag is cooled using cooling water in the cooling field, components in the blast furnace slag are leached into the cooling water.

  Moreover, when steelmaking slag, such as converter slag and hot metal desulfurization slag, contacts with rainwater or cooling water, the components in steelmaking slag leach out like blast furnace slag.

  The water in which components in the slag such as blast furnace slag and steelmaking slag are leached is referred to herein as “leached water”.

Among the components contained in this leachate, sulfur is S ^2- ion (form in sulfides such as hydrogen sulfide), thiosulfate ion (S ₂ O ₃ ^2- : S2 +), sulfite ion (SO ₃ ^2- : S4 +).

The form in which sulfur in the leachate can exist most stably is sulfate ion (SO ₄ ²⁻ : S6 +), but the reducing sulfur content such as S ²⁻ ion, thiosulfate ion and sulfite ion in the sulfide form is Since there is room for oxidation, it is measured as COD (Chemical Oxygen Demand: chemical oxygen demand: quantified using potassium permanganate) defined by the wastewater standards.

Therefore, when the wastewater standard cannot be satisfied, it cannot be discharged as it is, and a sulfur compound (hereinafter referred to as “sulfur-based COD component” or “sulfur-based reducing substance”) measured as COD is oxidized to sulfate ions ( SO ₄ ^2- ), reacted with Ca (OH) ₂ and recovered as gypsum (CaSO ₄ ), or released as harmless sulfate ion (SO ₄ ^2- ) after the oxidation treatment described above There is a need.

  Thus, as a method for treating sulfur-based COD components in waste water such as leachate, a method for biological treatment using bacteria such as sulfur-oxidizing bacteria has been proposed.

  For example, Patent Document 1 proposes a method of biologically treating a sulfur-based COD component using a fixed bed bioreactor in which sulfur-oxidizing bacteria are conditioned and grown on an immobilization carrier containing a calcium compound.

  Patent Document 2 proposes a treatment method using Pseudomonas bacteria having a sulfur oxidation function under neutral conditions.

  In Patent Document 3, activated sludge mixed water is put in an aeration tank of a facility for biological treatment of waste water, and waste water containing sulfur-based COD components and organic compounds are supplied to the aeration tank. Aeration tank aeration is controlled using the oxidation-reduction potential (ORP) as an index, and the pH in the aeration tank is controlled and managed in the range of 4.0 to 7.5 to acclimate and proliferate sulfur-oxidizing bacteria. However, methods for treating wastewater have been proposed.

  Patent Document 4 proposes a method of treating wastewater with sulfur-oxidizing bacteria while regularly adding rice bran or a phytic acid-containing organic compound as an organic nutrient source for sulfur-oxidizing bacteria.

  These are all intended to treat COD components under neutral to acidic conditions where the activity of sulfur-oxidizing bacteria is high, but unless the pH is controlled and managed properly, Although hydrogen sulfide is often generated and harmful, it does not mention any specific means for suppressing the generation of hydrogen sulfide to a level that does not cause a problem.

  That is, in biological treatment of waste water containing sulfur-based COD components, so-called sulfur-oxidizing bacteria that are capable of oxidizing and decomposing sulfur-based COD components are known to have neutral to weakly acidic pH and high activity. If the sulfide concentration is high, the sulfide becomes molecular hydrogen sulfide on the neutral to acidic side, and if diffused for the purpose of supplying oxygen necessary for living organisms, the hydrogen sulfide is diffused and there is a harmful problem.

  On the other hand, when the treatment is made alkaline, the amount of hydrogen sulfide generated can be reduced, but the activity is lowered, so that there is a problem that the reaction apparatus is enlarged.

  Therefore, a method for treating sulfur-based COD component-containing wastewater by controlling and managing it within a pH range (pH 8 to 9) in which hydrogen sulfide is not diffused and the activity of sulfur-oxidizing bacteria can be ensured to some extent can be considered.

  However, the pH of the inflow water (sulfur-based COD component-containing wastewater) to the treatment tank is usually about 12, and the pH of the neutralizer (such as sulfuric acid) is about 1, but the structure of the treatment tank, the inlet and outlet Depending on the position, the injection position of the neutralizing agent, and the like, there are not a few parts other than pH 8 to 9 in the treatment tank. There is a problem that causes it to occur.

  In addition, in order to control and manage the pH in the treatment tank to adjust the amount of neutralizing agent added, a pH meter (pH meter) is usually installed in the treatment tank. In order to grasp the pH distribution in detail, it is ideal to arrange all over in the treatment tank, but there is a problem that the installation cost increases, so depending on the arrangement of the pH meter, the pH of the treatment tank The distribution cannot be grasped correctly, the amount of neutralizing agent injected is excessive or insufficient, and there are not a few portions other than pH 8 to 9 in the treatment tank.

Japanese Patent Laid-Open No. 06-015294 Japanese Patent Laid-Open No. 08-323390 Japanese Patent Laid-Open No. 06-106187 Japanese Patent Application Laid-Open No. 07-251195

The present invention has been made to solve the above-described problems. When the waste water containing sulfur-based COD components generated in factories or the like is biologically treated and made sulfate ion (SO ₄ ²⁻ ) and rendered harmless. Another object of the present invention is to provide a biological treatment method and apparatus for sulfur-containing COD component-containing wastewater that can suppress the generation of harmful hydrogen sulfide.

That is, the present invention is as follows.
(1) In the biological treatment method for sulfur-based COD components using a microorganism-immobilizing material, the treatment liquid can be made to pass through a part of the partition wall of the treatment tank constituting the biological treatment apparatus, and the partition wall A biological treatment method for a sulfur-based COD component, wherein the pH is adjusted to 8 to 9 in each of the compartments sandwiched between them.
(2) A sulfur-based COD component biological treatment apparatus using a microorganism-immobilizing material, characterized in that the treatment liquid can be transported through a part of a partition wall of a treatment tank constituting the biological treatment apparatus. Biological treatment equipment for sulfur-based COD components.
(3) In the biological treatment apparatus for sulfur-based COD components using a microorganism-immobilizing material, the inflow of the treatment liquid into the treatment tank and the injection of the neutralizing agent into the treatment tank are both performed at two or more locations. A biological treatment apparatus for sulfur-based COD components, characterized in that

According to the present invention, a sulfur-based COD component-containing wastewater generated in a factory or the like is biologically treated, and when it is rendered harmless by sulfate ion (SO ₄ ^2- ), generation of harmful hydrogen sulfide can be suppressed. A biological treatment method and apparatus for wastewater containing COD components can be provided.

Diagram for explaining the first embodiment of the present invention Diagram for explaining the first embodiment of the present invention Diagram for explaining the effect of the present invention Diagram for explaining a second embodiment of the present invention

(First embodiment)
FIG. 1 shows a biological treatment apparatus 100 according to one embodiment of the present invention. FIG. 2 is a cross section of FIG. The biological treatment apparatus 100 has a microorganism fixed bed 7 that serves as a microorganism immobilization material, and a treatment liquid through an opening 15 provided in a part of the partition wall 14 of the treatment tank 1 constituting the biological treatment apparatus 100. L is available.

  In the example of FIG. 1 and FIG. 2, air is supplied from the blower 4 to the air diffuser 2 installed near the bottom of the processing tank 1, and the swirl flow F generated as the bubbles 3 are bubbled up. The oxygen dissolved in the processing liquid L described later is supplied from the bubbles 3 toward the microorganism fixed bed 7.

  And the partition wall 14 is installed in the depth direction approximate center of the process tank 1, and the stirring of the process liquid L is made to generate | occur | produce the swirling flow F on the near side and back side across the partition wall 14, and the process tank L is stirred. 1 as wide as possible.

  In addition, for example, sulfur-based COD component-containing wastewater such as leachate from which components in slag such as blast furnace slag and steelmaking slag have been leached is continuously or intermittently introduced into the treatment tank 1 and the inflow water 5 Inflow as. Then, water oxidized by microorganisms in the treatment tank 1 flows out from the treatment tank 1 as effluent water continuously or intermittently. In the treatment tank 1, the sulfur-based COD component-containing waste water is referred to as a treatment liquid L for convenience.

  As the microorganism fixed bed 7, various types such as those in which a mesh-like container filled with a string-like or granular carrier is fixed in the treatment tank 1 are suitable. As the material of the carrier, various materials such as plastic materials, cellulose materials, sponge materials, and the like are preferably used.

  Moreover, in the example of FIG. 1 and FIG. 2, although the processing tank 1 is divided into two divisions on both sides of the partition wall 14, you may make it partition into three or more divisions.

  In addition, like the example of FIG.1 and FIG.2, the diffuser 2 is installed in a part of the processing tank 1, and the processing tank which generate | occur | produces the swirling flow F in a tank is generally called a swirling flow type. ing.

  A device 9 for injecting a neutralizing agent 8, a pH electrode 10, a pH measuring device 11, and the like are installed in each section of the treatment tank 1 partitioned by the partition wall 14. The pH measured by the pH measuring device 11 is transferred to the device 9 for injecting the neutralizing agent 8 as information 12, and the flow rate when injecting the neutralizing agent is controlled. The partition wall 14 is provided with an opening 15 so that the processing liquid L can travel between the sections.

  The structure of the biological treatment apparatus 100 as shown in FIG. 1 and FIG. 2 prevents the high pH influent water 5 from flowing out without being sufficiently mixed with the treatment liquid L and the neutralizing agent 8 in the treatment tank 1. Can do.

  Moreover, since the neutralizing agent 8 can be individually injected into each compartment, the pH is adjusted to 8 to 9 suitable for biological treatment of sulfur-based COD component-containing wastewater in each compartment across the partition wall 14. And can be constantly managed at pH 8-9.

  When the pH is individually adjusted in each section, an error or malfunction may occur in any of the pH measuring devices in each section, or in the worst case, the equipment in a plurality of sections may become unusable due to equipment abnormality. Then, since each section is not a system that flows only in one direction but a system that flows in both directions, it can be adjusted to pH 8-9 stably.

  In the case of a swirling flow type treatment tank, the vicinity of the center of the treatment tank tends to be stagnant (dead water area), and the effective volume of the treatment tank is reduced. It is preferable to provide near the center and guide the flow toward the center of the processing tank 1.

  How many partition walls 14 are installed and how many compartments the treatment tank 1 is divided into depends on the flow rate of the influent water 5 and the capacity and shape of the treatment tank 1 and should be determined by numerical analysis, model experiment, and the like. Therefore, although it cannot be generally stated, in order to optimally treat the sulfur-based COD component-containing wastewater, it is necessary to strictly control the pH. Therefore, it is preferable to divide into as many compartments as possible.

FIG. 3 shows a biological treatment apparatus 100 having a swirling flow treatment tank 1 having a width of 7 m, a depth of 5 m, and a length of 15 m shown in FIG. 1, with respect to the number of divisions of the treatment tank 1 and the volume of the treatment tank 1. The ratio of the volume in the region exceeding pH 9 and the ratio of the volume in the region less than pH 8 are obtained by numerical analysis. The flow rate of the inflow water 5 is 5000 m ³ / day, and the flow rate of the diffuser is 625 m ³ / h. The injection device 9 for the neutralizing agent 8 is installed in the same number as the division number of the treatment tank 1.

  If the partition wall 14 is not present and the number of divisions is 1, it can be seen that a high pH region exceeding pH 9 is widely spread in the treatment tank 1.

  When the partition wall 14 is installed and the treatment tank 1 is divided, it can be seen that as the number of divisions increases, the region of high pH exceeding pH 9 decreases.

  In the treatment tank 1, when the inflowing water 5 has the above flow rate, even if the treatment tank 1 is divided into more than four, the effect is saturated. Therefore, the division number is preferably four or less.

(Second embodiment)
FIG. 4 shows a wastewater treatment apparatus 100 according to another embodiment of the present invention, in which the high pH inflow water 5 flows into the treatment tank 1 at two or more locations. By doing so, the treatment liquid L is agitated so that the uniformity of the concentration of the treatment liquid L can be as wide as possible in the treatment tank 1, and the formation of a high pH region in the treatment tank 1 is suppressed. can do.

  Moreover, injection | pouring of the neutralizing agent to the processing tank 1 is also performed at two or more places. By doing so, the treatment liquid L is agitated so that the uniformity of the concentration of the treatment liquid L can be as wide as possible in the treatment tank 1, and the formation of a high pH region in the treatment tank 1 is suppressed. can do.

  Furthermore, for the same reason, it becomes easier to adjust the pH to 8 to 9 in each compartment.

DESCRIPTION OF SYMBOLS 1 Treatment tank 2 Air diffuser 3 Air bubbles 4 Blower 5 Inflow water 6 Outflow water 7 Microbe fixed bed 8 Neutralizing agent 9 Neutralizing agent 8 injection device 10 pH electrode 11 pH measuring device 12 pH measurement value information 13 Partition wall 14 Partition Wall 15 Opening part F Swirling flow L Treatment liquid

Claims (3)

  In the biological treatment method for sulfur-based COD components using a microorganism-immobilizing material, the treatment liquid can be made to come and go through a part of the partition wall of the treatment tank constituting the biological treatment apparatus, and the partition wall is sandwiched. A biological treatment method for a sulfur-based COD component, wherein the pH is adjusted to 8 to 9 in each compartment.   A sulfur-based COD component biological treatment apparatus using a microorganism-immobilizing material, characterized in that a treatment liquid can be passed through a part of a partition wall of a treatment tank constituting the biological treatment apparatus. Biological treatment equipment for COD components.   In a biological treatment apparatus for sulfur-based COD components using a microorganism-immobilizing material, both inflow of a treatment liquid into a treatment tank and injection of a neutralizing agent into the treatment tank are performed at two or more locations. A biological treatment apparatus for sulfur-based COD components.

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