JP2017189743A - Method and device for treating wastewater containing organic deoxidizer and suspended matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce COD, while reducing the amount of generation of sludge, in the treatment of wastewater containing an organic deoxidizer and suspended matter.SOLUTION: A method for treating wastewater containing an organic deoxidizer and suspended matter includes: a mixture step for mixing a wastewater containing the organic deoxidizer and the suspended matter, an inorganic flocculant, and an oxidizer in a mixture tank 14, and a solid-liquid separation step for applying solid-liquid separation to the wastewater discharged from the mixture tank 14, with a filter 18.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for treating wastewater containing an organic oxygen scavenger and suspended substances and a technique for a treatment apparatus.

  For wastewater discharged from factories with boilers, etc., oxygen scavengers to prevent corrosion due to dissolved oxygen in the water, and scale inhibitors used to stabilize suspended substances and prevent hardness scales In many cases, it contains.

  Examples of the oxygen scavenger include organic oxygen scavengers. For example, plant-derived polyphenols such as tannic acid, oxycarboxylic acid, erythorbic acid, ascorbic acid, or salts thereof are used. Examples of the scale inhibitor include acrylic acid-based water-soluble polymers. These substances are COD sources. In addition, plant-derived polyphenols such as tannic acid and oxycarboxylic acids color waste water and appear as chromaticity (apparent chromaticity) when combined with turbidity.

Since COD _Mn of waste water is a waste water regulation item, it is necessary to reduce COD _Mn to a regulation value or less. Moreover, although there is no regulation about the chromaticity of the drainage, it looks bad and should be reduced in order to preserve the water environment at the discharge destination.

Conventionally, there is a method of reducing COD _Mn by passing drainage water through a packed bed filled with granular activated carbon, but it is not possible to sufficiently adsorb COD components, and chromaticity cannot be sufficiently reduced. Furthermore, since activated carbon breaks through early, there is a problem that it must be replaced frequently and the running cost is high.

  Thus, for example, in Patent Documents 1 to 3, after adding and mixing an organic coagulant, an inorganic flocculant, and activated carbon to wastewater containing an oxygen scavenger, a scale inhibitor, etc., coagulation precipitation is performed, and the oxygen scavenger A method for removing / reducing scale inhibitors and the like has been proposed.

JP 2004-81939 A JP 2006-7208 A JP 2009-297600 A

  In the methods of Patent Documents 1 to 3, depending on the components of the oxygen absorber and the scale inhibitor, the components can be insolubilized and removed by solid-liquid separation. When used as a component, there is a problem that it is difficult to insolubilize. Even when insolubilization is possible, there are the following problems.

(1) The added organic coagulant is insolubilized after agglomeration, and the amount of inorganic flocculant added is large, so that the amount of sludge generated is large. (2) If excess organic coagulant remains in the treated water due to fluctuations in the amount of the organic oxygen scavenger or scale inhibitor in the wastewater, it becomes a COD source, and the COD _{Mn of} the treated water does not decrease.

Therefore, an object of the present invention is to reduce COD _Mn while suppressing sludge generation in wastewater treatment containing an organic oxygen scavenger and suspended substances, and in particular, it is possible to reduce chromaticity for colored wastewater. It is providing the wastewater processing method and processing apparatus which become.

  One aspect of this embodiment is a solid-liquid separation of a wastewater containing an organic oxygen scavenger and a suspended substance, a mixing step of mixing an inorganic flocculant, and an oxidizing agent, and a wastewater discharged from the mixing step. And a solid-liquid separation step. A method for treating waste water containing an organic oxygen scavenger and suspended substances.

  One aspect of the present embodiment is a solid-liquid separation of a waste water containing an organic oxygen scavenger and a suspended substance, a first mixing step of mixing an inorganic flocculant, and a waste water discharged from the first mixing step. A first solid-liquid separation step; a second mixing step for mixing the waste water discharged from the first solid-liquid separation step; and an oxidizing agent; and a second solid-liquid separation for the waste water discharged from the second mixing step. A solid-liquid separation step, and an organic oxygen scavenger and a wastewater treatment method containing suspended solids.

  In the wastewater treatment method, the solid-liquid separation in the solid-liquid separation step and the second solid-liquid separation step is preferably a filtration treatment.

  In the wastewater treatment method, it is preferable that the inorganic flocculant includes at least one of an aluminum salt and a ferric salt, and the oxidizing agent includes a sodium hypochlorite solution.

  One aspect of the present embodiment is a solid-liquid separation of a wastewater containing an organic oxygen scavenger and a suspended substance, a mixing means for mixing an inorganic flocculant, and an oxidizing agent, and a wastewater discharged from the mixing means. An apparatus for treating waste water containing an organic oxygen scavenger and a suspended substance.

  One aspect of the present embodiment is a solid-liquid separation of the waste water containing the organic oxygen scavenger and the suspended substance, the first mixing means for mixing the inorganic flocculant, and the waste water discharged from the first mixing means. The first solid-liquid separation means, the waste water discharged from the first solid-liquid separation means, the second mixing means for mixing the oxidant, and the second solid-liquid separation of the waste water discharged from the second mixing means. An apparatus for treating waste water containing an organic oxygen scavenger and suspended substances.

  In the wastewater treatment apparatus, it is preferable that the solid-liquid separation means and the second solid-liquid separation means are filters.

  In the wastewater treatment apparatus, it is preferable that the inorganic flocculant includes at least one of an aluminum salt and a ferric salt, and the oxidizing agent includes a sodium hypochlorite solution.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to reduce COD _Mn , suppressing the sludge generation amount in the waste water treatment containing an organic oxygen absorber and a suspended substance. In particular, chromaticity can be reduced for colored wastewater.

It is a schematic block diagram of the waste water treatment equipment concerning this embodiment. It is a schematic block diagram which shows another example of the waste water treatment equipment which concerns on this embodiment. It is a schematic block diagram which shows another example of the waste water treatment equipment which concerns on this embodiment. It is a schematic block diagram which shows another example of the waste water treatment equipment which concerns on this embodiment.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

  FIG. 1 is a schematic configuration diagram of a wastewater treatment apparatus according to the present embodiment. The wastewater treatment apparatus 1 shown in FIG. 1 includes a raw water tank 10, a raw water pump 12, a mixing tank 14, and a filter 18 filled with a filter medium 16. In the mixing tank 14, a stirrer 20 and a pH meter 22 are installed.

  The waste water treatment apparatus 1 shown in FIG. 1 includes waste water inflow lines 24a and 24b, a treated water discharge line 26, an oxidant addition line 28, an inorganic flocculant addition line 30, and a pH adjuster addition line 32. The raw water pump 12 is installed in the drainage inflow line 24a.

  One end of the drainage inflow line 24 a is connected to the drainage outlet of the raw water tank 10, and the other end is connected to the drainage inlet of the mixing tank 14. One end of the drainage inflow line 24 b is connected to the drainage outlet of the mixing tank 14, and the other end is connected to the drainage inlet of the filter 18. The treated water discharge line 26 is connected to the treated water outlet of the filter 18.

  An oxidant addition line 28, an inorganic flocculant addition line 30, and a pH adjuster addition line 32 are connected to the raw water tank 10. In the wastewater treatment apparatus 1 of FIG. 1, for example, an oxidant is fed from an oxidant addition device (not shown) to an oxidant addition line 28, and inorganic flocculation is performed from an inorganic flocculant addition device (not shown) to an inorganic flocculant addition line 30. The agent is fed, and the pH adjuster is sent from a pH adjuster addition device (not shown) to the pH adjuster addition line 32. In addition, you may send each chemical | medical agent to each line by an operator etc., without installing each addition apparatus.

  The wastewater to be treated is wastewater containing an organic oxygen scavenger and suspended substances, and specific examples include boiler wastewater, cooling tower wastewater, plating washing wastewater discharged from the plating industry, and the like. Examples of the organic oxygen scavenger include plant-derived polyphenols such as tannic acid, oxycarboxylic acid, erythorbic acid, ascorbic acid, or salts thereof. Examples of the suspended substance include a compound of polyphenol and iron, iron oxide, and the like. Examples of the compound of polyphenol and iron include a compound of tannic acid such as condensed tannin and hydrolyzed tannin and iron. The wastewater to be treated may contain a scale inhibitor such as an acrylic acid-based water-soluble polymer, and the acrylic acid-based water-soluble polymer is, for example, acrylic acid, acrylamidomethylpropane sulfonic acid, or N-substituted acrylamide. A terpolymer etc. are mentioned.

  An example of the operation of the waste water treatment apparatus 1 shown in FIG. 1 will be described.

  The waste water containing the organic oxygen scavenger and suspended substances is once stored in the raw water tank 10. And the raw | natural water pump 12 is operated and the waste_water | drain in the raw | natural water tank 10 is supplied to the mixing tank 14 from the waste_water | drain inflow line 24a. At this time, the oxidizing agent and the flocculant are added to the mixing tank 14 from the oxidizing agent addition line 28 and the inorganic flocculant addition line 30. Moreover, a pH adjuster is added to the mixing tank 14 from the pH adjuster addition line 32 as needed.

In the mixing tank 14, the stirrer 20 mixes the waste water containing the organic oxygen scavenger and the suspended substance, the oxidizing agent, and the inorganic flocculant (mixing step). At this time, a part of the suspended substance (particularly suspended substance having a relatively large particle size) is combined with the inorganic flocculant to become coarse, and is easily captured by the filter medium 16 of the subsequent filter 18. Become. In addition, part of the suspended matter, organic oxygen scavenger, scale inhibitor, and the like are oxidatively decomposed by the oxidizing agent, and COD _Mn in the waste water is reduced. In the present embodiment, even if the wastewater is colored with a coloring component such as tannic acid or other plant-derived polyphenol or oxycarboxylic acid in the wastewater, since these coloring components are oxidatively decomposed by the oxidizing agent, The drainage is decolorized and the chromaticity is reduced.

  The wastewater mixed in the mixing tank 14 for a predetermined time is supplied to the filter 18 from the wastewater inflow line 24b and is subjected to solid-liquid separation (solid-liquid separation step). Specifically, suspended substances and the like are captured by the filter medium 16 in the process in which the wastewater passes through the filter medium 16 in the filter 18. Moreover, when the aggregation reaction on the surface of the filter medium 16 is promoted by the presence of the inorganic flocculant in the waste water, and the trapping of suspended substances on the surface of the filter medium 16 proceeds, dissolved components (organic oxygen scavenger and scale prevention in the waste water). Part of the agent or the like is captured by the filter medium 16. And the waste_water | drain isolate | separated by the filter 18 is discharged | emitted out of the system from the treated water discharge line 26 as treated water.

In this embodiment, by adding an oxidizing agent, dissolved components such as an organic oxygen scavenger and a scale inhibitor are oxidized to reduce COD _Mn, which cannot be completely oxidized by the oxidizing agent, but insoluble matter that contributes to COD _Mn . Since only the water is removed by filtration or the like, the amount of sludge generated during wastewater treatment can be suppressed.

  FIG. 2 is a schematic configuration diagram illustrating another example of the waste water treatment apparatus according to the present embodiment. In the waste water treatment apparatus 2 shown in FIG. 2, the same code | symbol is attached | subjected about the structure similar to the waste water treatment apparatus 1 shown in FIG. The waste water treatment apparatus 2 shown in FIG. 2 includes a raw water tank 10, a raw water pump 12, a first line mixer 14a, a first filter 18a filled with a filter medium 16, a second line mixer 14b, and a second filter filled with a filter medium 16. 18b.

  The waste water treatment apparatus 2 shown in FIG. 2 includes waste water inflow lines 24a, 24b, 24c, and 24d, a treated water discharge line 26, an oxidant addition line 28, an inorganic flocculant addition line 30, and a pH adjuster addition line 32. . The raw water pump 12 is installed in the drainage inflow line 24a. A pH meter 22 is installed in the drainage inflow line 24b.

  One end of the drainage inflow line 24a is connected to the drainage outlet of the raw water tank 10, and the other end is connected to the drainage inlet of the first line mixer 14a. One end of the drainage inflow line 24b is connected to the drainage outlet of the first line mixer 14a, and the other end is connected to the drainage inlet of the first filter 18a. One end of the drainage inflow line 24c is connected to the drainage outlet of the first filter 18a, and the other end is connected to the drainage inlet of the second line mixer 14b. One end of the drainage inflow line 24d is connected to the drainage outlet of the second line mixer 14b, and the other end is connected to the drainage inlet of the second filter 18b. The treated water discharge line 26 is connected to the treated water outlet of the second filter 18b.

  An inorganic flocculant addition line 30 and a pH adjuster addition line 32 are connected to the drainage inflow line 24a. An oxidant addition line 28 is connected to the drainage inflow line 24c.

  An example of operation | movement of the waste water treatment apparatus 2 shown in FIG. 2 is demonstrated.

  The wastewater containing the organic oxygen scavenger and the suspended substance is stored in the raw water tank 10 once. And the raw | natural water pump 12 is operated and the waste_water | drain in the raw | natural water tank 10 is supplied to the 1st line mixer 14a from the waste_water | drain inflow line 24a. At this time, the flocculant is supplied from the inorganic flocculant addition line 30 to the first line mixer 14a. Moreover, a pH adjuster is supplied to the 1st line mixer 14a from the pH adjuster addition line 32 as needed.

  In the first line mixer 14a, the waste water containing the organic oxygen scavenger and the suspended substance and the inorganic flocculant are mixed (first mixing step). At this time, a part of the suspended substance (particularly, the suspended substance having a relatively large particle size) is combined with the inorganic flocculant to be coarsened and is easily captured by the subsequent filter medium 16.

  The waste water that has passed through the first line mixer 14a is supplied from the waste water inflow line 24b to the first filter 18a and is subjected to solid-liquid separation (first solid-liquid separation step). Specifically, suspended substances are captured by the filter medium 16 in the process in which the wastewater passes through the filter medium 16 in the first filter 18a. Moreover, when the aggregation reaction on the surface of the filter medium 16 is promoted by the presence of the inorganic flocculant in the waste water, and the trapping of suspended substances on the surface of the filter medium 16 proceeds, dissolved components (organic oxygen scavenger and scale prevention in the waste water). Part of the agent or the like is captured by the filter medium 16.

  The wastewater separated by solid and liquid by the first filter 18a is supplied from the wastewater inflow line 24c to the second line mixer 14b. At this time, the oxidizing agent is supplied from the oxidizing agent addition line 28 to the second line mixer 14b, and the waste water and the oxidizing agent are mixed (second mixing step). The wastewater that has passed through the second line mixer 14b is supplied from the wastewater inflow line 24d to the second filter 18b and is subjected to solid-liquid separation (second solid-liquid separation step).

In the second line mixer 14b and the second filter 18b, part of suspended substances in the waste water, organic oxygen scavenger, scale inhibitor and the like are oxidized and decomposed by the oxidizing agent, and COD _Mn in the waste water is reduced. Moreover, the colored waste water is decolored and chromaticity is reduced. Further, in the second filter 18b, suspended substances remaining in the waste water and a part of the dissolved components in the waste water are captured by the filter medium 16. Further, if the inorganic flocculant remains in the waste water, a part of the oxidized dissolved component (organic oxygen scavenger and scale inhibitor) is aggregated and insolubilized and captured by the filter medium 16 of the second filter 18b. The However, since only insoluble matter that cannot be oxidized by the oxidizing agent but contributes to COD _Mn is removed by filtration or the like, the amount of sludge generated during waste water treatment can be suppressed.

Since the oxidizing agent is also consumed by suspended solids, when the concentration of suspended solids in the wastewater is high, the wastewater and the flocculant are mixed and suspended by a subsequent filter as in the wastewater treatment device 2 of FIG. After removing suspended substances, the treatment method of mixing the wastewater from which suspended substances are removed and the oxidizing agent to oxidize the organic oxygen scavenger in the wastewater can reduce COD _Mn in the wastewater more efficiently. Can do. On the other hand, when the concentration of suspended solids in the wastewater is low, the amount of oxidant consumed by the suspended solids is small. Therefore, as in the wastewater treatment apparatus 1 in FIG. A method of solid-liquid separation with a subsequent filter is simple and preferred. For example, when the suspended solid concentration in the wastewater is less than 15 mg / L, it is preferable to carry out the wastewater treatment by the wastewater treatment apparatus 1 in FIG. 1, and in the case where the suspended solid concentration in the wastewater is 15 mg / L or more, It is preferable to carry out wastewater treatment by the wastewater treatment device 2.

  The wastewater treatment apparatus of this embodiment measures the suspended solid concentration of wastewater, and sends the wastewater to the wastewater treatment apparatus shown in FIG. 1 based on the suspended solid concentration of wastewater, or the wastewater shown in FIG. You may provide the switching system which sends a liquid to a processing apparatus. In the case of the wastewater treatment apparatus 1 shown in FIG. 1, the concentration of suspended solids in wastewater is measured. If the concentration of suspended solids in the wastewater is equal to or greater than a predetermined value, After the solids and liquids are mixed, the treated water that has undergone solid-liquid separation is returned to the mixing tank 14, the treated water and the oxidizing agent are mixed, and the solid-liquid separation may be performed again.

  Hereinafter, conditions and modifications of each process will be described.

<Mixing step, first mixing step, second mixing step>
The oxidizing agent used in the mixing step and the second mixing step is not particularly limited as long as it can oxidatively decompose the organic oxygen scavenger. For example, sodium hypochlorite, ozone-containing water, A chlorine dioxide solution etc. are mentioned. Among these, sodium hypochlorite is preferable because it is easy to handle and inexpensive. In the case of using sodium hypochlorite, as the residual chlorine concentration in the treated water is less than 3mgCl 2 / _L, it is desirable to be added to the wastewater.

The amount of the oxidant added depends on the concentration of the organic oxygen scavenger in the waste water, but is preferably in the range of 1 to 10 times the COD _Mn of the waste water, for example. In particular, when a sodium hypochlorite solution is used as the oxidizing agent, the amount of sodium hypochlorite that is an active ingredient is more preferably in the range of 1 to 3 times the COD _Mn of the waste water. If the amount of sodium hypochlorite solution added is less than 1 times the amount of COD _{Mn in} the wastewater, the organic oxygen scavenger may not be fully oxidized. Therefore, the degree of reduction of COD _{Mn in} the treated water is small, and the chemical cost may be great.

  The inorganic flocculant used in the mixing step and the first mixing step is a conventionally known inorganic flocculant, preferably a ferric chloride solution or a ferric salt solution of a ferric sulfate solution, a polyaluminum chloride solution. Or it is preferable to contain at least any one among aluminum salt solutions, such as an aluminum sulfate solution. After the addition of the inorganic flocculant, it is desirable to immediately stir and mix in order to efficiently perform charge neutralization of the suspended substance.

  Although the amount of the inorganic flocculant added depends on the amount of suspended substances in the waste water, for example, a range of 0.01 to 0.05 is preferable, and a range of 0.02 to 0.04 is more preferable. When the added amount of the inorganic flocculant is less than 0.01, the flocculating property of the suspended substance may be lowered, and when it exceeds 0.05, the filter may be clogged earlier.

  The mixing device used in the mixing step, the first mixing step, and the second mixing step may be a mixing tank equipped with a stirrer, a line mixer, or other mixing device.

The pH in the mixing step is preferably adjusted to a range of 6.0 to 8.0. When the pH is less than 6.0, the oxidizing agent is gasified (for example, hypochlorous acid becomes chlorine gas) and is easily volatilized from water. When the pH exceeds 8.0, the oxidizing power of the oxidizing agent is reduced. There are inconveniences such as the effect of reducing COD _Mn is reduced, or the pH must be lowered during discharge.

  The pH in the first mixing step is preferably adjusted to a range of 5.0 to 7.0, and in particular when ferric salt is used as a flocculant, the pH is adjusted to a range of 5.0 to 6.5. It is preferable. By making pH into the said range, it becomes possible to raise the removal effect of soluble components, such as an organic oxygen absorber in waste_water | drain.

The pH in the second mixing step is preferably adjusted to a range of 6.0 to 8.0. When the pH is less than 6.0, the oxidizing agent is gasified (for example, hypochlorous acid becomes chlorine gas) and is easily volatilized from water. When the pH is above 8.0, the oxidizing power of the oxidizing agent is reduced. However, there is a disadvantage that the effect of reducing COD _Mn is reduced, or the pH must be lowered during discharge. In the waste water treatment apparatus 2 shown in FIG. 2, for example, it is desirable to perform pH adjustment by installing a pH adjusting agent addition line in the waste water inflow line 24 c.

  The pH adjustment in the mixing step, the first mixing step, and the second mixing step is performed, for example, by adjusting the addition amount of the pH adjusting agent based on the pH value measured by the pH meter 22. In the case of using the mixing tank 14, the pH meter 22 is preferably installed in the mixing tank 14, and in the case of using the line mixer (14a, 14b), the pH meter 22 is inflow of drainage downstream of the line mixer (14a, 14b). It is preferably installed in the line (24b, 24d) or the filter (18a, 18b). Examples of the pH adjuster include acid solutions such as sulfuric acid and hydrochloric acid, and alkali solutions such as sodium hydroxide.

<Solid-liquid separation step, first solid-liquid separation step, second solid-liquid separation step>
The solid-liquid separation of the waste water in the solid-liquid separation step, the first solid-liquid separation step, and the second solid-liquid separation step is not limited to the filtration treatment. For example, the precipitation treatment, the floating separation treatment with fine bubbles, etc. Can be mentioned. In particular, the solid-liquid separation of the waste water in the solid-liquid separation step and the second solid-liquid separation step is preferably a filtration treatment in terms of the removal rate of suspended substances. Moreover, the solid-liquid separation of the waste water in the first solid-liquid separation step is preferably a filtration treatment or a precipitation treatment in terms of energy saving. In addition to the sand filtration process that removes impurities such as suspended substances by passing wastewater through a sand filter, the filtration process removes impurities such as suspended substances by passing the wastewater through a membrane filter, for example. And membrane filtration treatment. Among these, sand filtration using a sand filter is preferable in terms of ease of recovery when the filter medium is blocked.

  A sand filter is comprised from the tower etc. which were filled with filter media, such as quartz sand, anthracite, and manganese sand, for example. When using a sand filter, it is preferable to use a filter medium amount and a water flow rate that can ensure a sufficient contact time between the drainage and the filter medium. The contact time between the drainage and the filter medium is preferably 10 minutes or more, for example. Examples of the filtration method of the sand filter include a gravity method and a pressure method. A membrane filter is comprised from the membrane module etc. which installed filter media, such as a microfiltration membrane (MF membrane) and an ultrafiltration membrane (UF membrane), for example. Examples of the filtration method of the membrane filter include a cross flow filtration method and a total filtration method.

  When a filter is used for solid-liquid separation of waste water in the solid-liquid separation process, the first solid-liquid separation process, and the second solid-liquid separation process, for example, the differential pressure before and after the packed bed of the filter medium is a predetermined value. It is preferable that the filter is backwashed with treated water (backwashing process) to prevent the filter from being blocked. Below, the structure of the waste water treatment equipment provided with the system which backwashes a filter is illustrated.

  FIG. 3 is a schematic configuration diagram illustrating another example of the waste water treatment apparatus according to the present embodiment. In the waste water treatment apparatus 3 of FIG. 3, the same components as those of the waste water treatment apparatus 1 of FIG. The waste water treatment apparatus 3 of FIG. 3 includes a backwash system that backwashes the filter 18. The backwash system includes a backwash blower 34, an air inflow line 36, a backwash pump 38, backwash drainage lines 40a and 40b, a treated water storage tank 42, and a backwash drainage storage tank 44.

  One end of the air inflow line 36 is connected to the backwash blower 34, and the other end is disposed below the filter 18 below the filter medium 16. One end of the backwash drainage line 40 a is connected to the treated water storage tank 42, and the other end is connected to the treated water discharge line 26. A backwash pump 38 is installed in the backwash drainage line 40a. One end of the backwash drainage line 40 b is connected to the upper outlet of the filter 18, and the other end is connected to the backwash drainage storage tank 44.

  In the waste water treatment apparatus 3 of FIG. 3, for example, the backwash blower 34 is operated, and air is introduced from the air inflow line 36 to the lower part of the filter 18. Further, the backwash pump 38 is operated, and the treated water in the treated water storage tank 42 is introduced into the lower portion of the filter 18 through the backwash drainage line 40 a and the treated water discharge line 26. The air and treated water introduced into the lower part of the filter 18 become an upward flow and pass through the filter medium 16. At this time, suspended substances and the like captured by the filter medium 16 are removed. The treated water containing suspended substances and the like passes through the backwash drainage line 40 b and is supplied to the backwash drainage storage tank 44.

  FIG. 4 is a schematic configuration diagram illustrating another example of the waste water treatment apparatus according to the present embodiment. In the waste water treatment apparatus 4 of FIG. 4, the same code | symbol is attached | subjected about the structure similar to the waste water treatment apparatus 2 of FIG. 2, and the description is abbreviate | omitted. 4 includes a backwash blower 34, an air inflow line 36, a backwash pump 38, backwash drainage lines 40a and 40b, a treated water storage tank 42, and a backwash drainage storage tank 44. Has a system. In the waste water treatment apparatus 4 of FIG. 4, only the backwashing system for backwashing the 2nd filter 18b is shown in figure. Although illustration of the backwashing system for backwashing the 1st filter 18a is abbreviate | omitted, for example, the backwashing system of the structure similar to the backwashing system shown in FIG. 4 is attached.

  One end of the air inflow line 36 is connected to the backwash blower 34, and the other end is disposed below the second filter 18 b below the filter medium 16. One end of the backwash drainage line 40 a is connected to the treated water storage tank 42, and the other end is connected to the treated water discharge line 26. A backwash pump 38 is installed in the backwash drainage line 40a. One end of the backwash drainage line 40 b is connected to the upper outlet of the second filter 18 b, and the other end is connected to the backwash drainage storage tank 44.

  Backwashing of the second filter 18b is performed by the backwashing system shown in FIG. Moreover, the backwashing of the 1st filter 18a is also performed by the backwashing system not shown.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail more concretely, this invention is not limited to a following example.

(Example 1-1, Example 1-2, Comparative example 1-1, Comparative example 1-2, Comparative example 1-3)
Blow water (boiler drainage) from a boiler containing an organic oxygen scavenger (polyphenol) and an acrylic acid terpolymer with the water quality shown in Table 1 was used as raw water to be treated.

  The raw water was treated using the waste water treatment apparatus shown in FIG. Table 2 shows the apparatus specifications of Examples and Comparative Examples.

  In Examples 1-1 to 1-2, raw water was passed through the treatment apparatus of FIG. 3 at a flow rate of 90 L / h. In Example 1-1, 1 mg Fe / L of ferric chloride solution and 60 mg NaClO / L of sodium hypochlorite solution were added to the mixing tank, and in Example 1-2, 1 mg Fe / L of hypochlorous acid solution and hypochlorous acid were added. 90 mg NaClO / L sodium chlorate solution was added. The reaction pH in the mixing tank was 6.2.

  In Comparative Examples 1-1 to 1-3, raw water was passed through the apparatus of FIG. 3 at a flow rate of 90 L / h. In Comparative Example 1-1, only 90 mg NaClO / L of sodium hypochlorite solution was added to the mixing tank. In Comparative Example 1-2, only 1 mg Fe / L of ferric chloride solution was added. In Comparative Example 1-3, 1 mg Fe / L of a ferric solution and 2500 mg / L of a 1% aqueous solution of polydimethyldiallylammonium chloride (hereinafter referred to as DADMAC) as an organic coagulant were added. The reaction pH in the mixing tank was 6.2 in each comparative example.

In each of the examples (1-1 to 1-2) and the comparative examples (1-1 to 1-3), the treated water was collected after 5 hours from the start of water flow, and the pH of the treated water, COD _Mn , suspension The substance concentration (SS), chromaticity (apparent chromaticity), and residual chlorine concentration were measured. The pH, COD _Mn , and suspended substance concentration were measured by the methods specified in JIS0102. When there was residual chlorine in the measurement of COD _Mn , sodium sulfite was added to reduce the residual chlorine to 0.3 mg / L or less, and then COD _Mn was measured. The apparent chromaticity was measured based on the water test method (2011) without filtering with filter paper or the like. Table 3 summarizes the water quality results of the treated water of Examples (1-1, 1-2) and Comparative Examples (1-1 to 1-3).

  In addition, in all of Examples (1-1 to 1-2) and Comparative Examples (1-1 to 1-3), air backwashing and water backwashing with treated water were performed 24 hours after passing water. All the backwash wastewater was collected, and the suspended matter concentration (sludge concentration) in the backwash wastewater and the amount of suspended matter (sludge generation amount) generated by passing water for 24 hours were determined. Table 3 summarizes the suspended matter concentration and the amount of suspended matter (sludge generation amount) in the backwash waste water of Examples (1-1, 1-2) and Comparative Examples (1-1 to 1-3).

  In addition, in all of the examples (1-1, 1-2) and the comparative examples (1-1 to 1-3), water above the filter medium packed bed was collected at 4.5 hours from the start of water flow. The suspended substance concentration was measured. This is summarized in Table 3 as the suspended matter concentration at the top of the filter.

(Results of Example 1-1 and Example 1-2)
Regarding the water quality of the treated water of Examples 1-1 and 1-2, after adding and mixing sodium hypochlorite and ferric chloride, Example 1-1 in which the amount of sodium hypochlorite added is relatively small is: COD _Mn was 18 mg / L, and apparent chromaticity was 59 degrees. Moreover, Example 1-2 with much sodium hypochlorite addition amount became water quality better than Example 1-1, COD _Mn was 14 mg / L, and apparent chromaticity was 36 degree | times. The suspended solid concentrations at the top of the filter were 12, 13 mg / L, respectively. The suspended matter concentration in the backwash wastewater was 580 to 620 mg / L, and the suspended matter amount (sludge generation amount) in the backwash wastewater was 26 to 28 g / 45 L.

(Results of Comparative Examples 1-1 to 1-3)
In Comparative Example 1-1 in which only sodium hypochlorite was added, the COD _{Mn of} the treated water was 22 mg / L, and the apparent chromaticity was 62 degrees. In Comparative Example 1-1, the same amount of sodium hypochlorite was added as in Example 1-2, but COD _Mn , apparent chromaticity, and suspended substance concentration all had high values. The reason why COD _Mn and the apparent chromaticity are high is considered to be that a large amount of suspended substances leaked into the treated water due to the absence of the flocculant. Moreover, in the comparative example 1-2 which added only ferric chloride, COD _{Mn of} treated water is 32 mg / L and an apparent chromaticity is 138 degree | times, Comparing with an Example (1-1, 1-2). It was very high. In Comparative Example 1-3 in which ferric chloride and DADMAC were added, COD _{Mn of} the treated water was 19 mg / L, which was a value close to Example (1-1, 1-2). The degree was 83 degrees, which was higher than the examples (1-1, 1-2). Moreover, the suspended substance density | concentration in the upper part of the filter of Comparative Example 1-3, and the suspended substance density | concentration of backwash waste_water | drain are higher than an Example (1-1, 1-2), and also the suspended matter of backwash waste_water | drain The amount (sludge generation amount) was 2.6 times that of Example 1-2.

  As described above, the treated water quality of Examples (1-1, 1-2) is better than Comparative Examples (1-1 to 1-2), and more than Comparative Example 1-3 using DADMAC. The result that the sludge generation amount decreased was obtained. Thereby, it can be said that the effectiveness of the filtered example was confirmed after sodium hypochlorite and ferric chloride were added and mixed.

(Example 2-1 and Example 2-2)
Blow water (boiler wastewater) from a boiler containing the organic oxygen absorber (polyphenol) and acrylic acid terpolymer is used as the raw water to be treated with the water quality shown in Table 4 (having more suspended matter than the water quality shown in Table 1) did.

  The raw water was treated using the waste water treatment apparatus shown in FIG. Table 5 shows the device specifications.

In Example 2-1, raw water was passed through the waste water treatment apparatus of FIG. 4 at a flow rate of 90 L / h. However, in Example 2-1, 2 mg Fe / L of ferric chloride solution and 65 mg NaClO / L of sodium hypochlorite solution were added to the raw water, mixed in the first stage mixer, and then filtered in the first stage. The processing method of only filtering with a filter was carried out (the second-stage mixer and filter were not used). Then, 5 hours after the start of water flow, the treated water discharged from the first-stage filter is collected, and the pH, COD _Mn , suspended substance concentration (SS), and chromaticity (apparent chromaticity) of the treated water are measured. It was measured. In addition, 24 hours after passing water, the first-stage filter was subjected to air backwash and water backwash with treated water. All the backwash wastewater (90 L) was collected, and the suspended matter concentration (sludge concentration) in the backwash wastewater and the amount of suspended matter (sludge generation amount) generated by passing water for 24 hours were determined. These results are summarized in Table 6.

In Example 2-2, raw water was passed through the waste water treatment apparatus of FIG. 4 at a flow rate of 90 L / h. Also, 2 mg Fe / L of ferric chloride solution is added to the raw water, mixed in the first stage mixer, filtered through the first stage filter, and hypochlorous acid is added to the filtered water (intermediate treated water). The sodium solution was added with 65 mg NaClO / L, mixed with the second-stage mixer, and then filtered with the second-stage filter. Five hours after the start of water flow, the intermediate treated water discharged from the first-stage filter and the final treated water discharged from the second-stage filter are collected, and the pH, COD of the intermediate treated water and the final treated water are collected. _Mn , suspended substance concentration (SS), chromaticity (apparent chromaticity), and residual chlorine concentration were measured. In addition, 24 hours after passing water, the first-stage and second-stage filters were subjected to air backwash and water backwash with final treated water. All the backwash wastewater (90 L) was collected, and the suspended matter concentration (sludge concentration) in the backwash wastewater and the amount of suspended matter (sludge generation amount) generated by passing water for 24 hours were determined. These results are summarized in Table 6.

(Comparative Example 2)
In Comparative Example 2, raw water was passed through the waste water treatment apparatus of FIG. 4 at a flow rate of 90 L / h. In addition, 65 mg NaClO / L of sodium hypochlorite solution is added to the raw water, mixed in the first-stage mixer, filtered through the first-stage filter, and the filtered water (intermediate treated water) is added with second chloride. Iron was added in an amount of 2 mg Fe / L, mixed with a second-stage mixer, and then filtered with a second-stage filter. Five hours after the start of water flow, the intermediate treated water discharged from the first-stage filter and the final treated water discharged from the second-stage filter are collected, and the pH, COD of the intermediate treated water and the final treated water are collected. _Mn , suspended substance concentration (SS), chromaticity (apparent chromaticity), and residual chlorine concentration were measured. In addition, 24 hours after passing water, the first-stage and second-stage filters were subjected to air backwash and water backwash with final treated water. All the backwash wastewater (90 L) was collected, and the suspended matter concentration (sludge concentration) in the backwash wastewater and the amount of suspended matter (sludge generation amount) generated by passing water for 24 hours were determined. These results are summarized in Table 6.

(Results of Example 2-1 and Example 2-2)
In Example 2-1, in which sodium hypochlorite and ferric chloride were added and mixed at the same time and filtered, the treated water had a COD _Mn of 17 mg / L and an apparent chromaticity of 38 degrees. After adding and mixing ferric chloride and filtering, sodium hypochlorite was added and mixed and filtered. In Example 2-2, the treated water quality was better than in Example 2-1, and COD _Mn was 12 mg. / L, apparent chromaticity was 23 degrees. That is, when the concentration of suspended solids in raw water was high, it was found that better treated water quality was obtained by performing the treatment method of Example 2-2 than the treatment method of Example 2-1. The suspended substance concentration in the backwash wastewater of Example 2-1 and Example 2-2 is 600 to 610 mg / L, and the suspended solid amount (sludge generation amount) in the backwash wastewater is 54 to 55 g / 90 L. Met.

(Results of Comparative Example 2)
In Comparative Example 2 in which the addition order of sodium hypochlorite and ferric chloride was added in the reverse order of Example 2-2, the water quality of the final treated water was 20 mg / L COD _Mn and the apparent chromaticity was It was 51 degrees. Although the COD _{Mn of the} final treated water was lower than that of the intermediate treated water (23 mg / L), the apparent chromaticity was higher than that of the intermediate treated water (45 degrees). The cause of the increase in chromaticity is considered to be that ferric chloride iron added to the intermediate treated water leaked from the second-stage filter. Moreover, although the sodium hypochlorite addition amount of the comparative example 2 was larger than Example 2-2, COD _{Mn of the} final treated water became higher than Example 2-2.

  1-4 Wastewater treatment device, 10 raw water tank, 12 raw water pump, 14 mixing tank, 14a 1st line mixer, 14b 2nd line mixer, 16 filter medium, 18, 18a, 18b filter, 20 stirrer, 22 pH meter, 24a, 24b, 24c, 24d Wastewater inflow line, 26 Treated water discharge line, 28 Oxidant addition line, 30 Inorganic flocculant addition line, 32 pH adjuster addition line, 34 Backwash blower, 36 Air inflow line, 38 Backwash Pump, 40a, 40b Backwash drainage line, 42 treated water storage tank, 44 backwash drainage storage tank.

Claims (8)

A mixing step of mixing the wastewater containing the organic oxygen scavenger and the suspended solids, the inorganic flocculant, and the oxidizing agent;
And a solid-liquid separation step of solid-liquid separation of the waste water discharged from the mixing step. A method for treating waste water containing an organic oxygen scavenger and a suspended substance. A first mixing step of mixing an organic oxygen scavenger and waste water containing suspended solids with an inorganic flocculant;
A first solid-liquid separation step for solid-liquid separation of the waste water discharged from the first mixing step;
A second mixing step of mixing waste water discharged from the first solid-liquid separation step and an oxidizing agent;
And a second solid-liquid separation step for solid-liquid separation of the wastewater discharged from the second mixing step. A method for treating wastewater containing an organic oxygen scavenger and a suspended substance.   3. The method for treating wastewater according to claim 1 or 2, wherein the solid-liquid separation in the solid-liquid separation step and the second solid-liquid separation step is a filtration treatment. A method for treating wastewater containing substances.   The wastewater treatment method according to any one of claims 1 to 3, wherein the inorganic flocculant includes at least one of an aluminum salt and a ferric salt, and the oxidizing agent is hypochlorous acid. A method for treating wastewater containing an organic oxygen scavenger and suspended solids, comprising an acid sodium solution. A mixing means for mixing the waste water containing the organic oxygen scavenger and the suspended solids, the inorganic flocculant, and the oxidizing agent;
And a solid-liquid separation means for solid-liquid separation of the wastewater discharged from the mixing means. A wastewater treatment apparatus containing an organic oxygen scavenger and a suspended substance. A first mixing means for mixing the waste water containing the organic oxygen scavenger and the suspended substance and the inorganic flocculant;
First solid-liquid separation means for solid-liquid separation of waste water discharged from the first mixing means;
A second mixing means for mixing waste water discharged from the first solid-liquid separation means and an oxidizing agent;
And a second solid-liquid separation means for solid-liquid separation of the wastewater discharged from the second mixing means. A wastewater treatment apparatus containing an organic oxygen scavenger and a suspended substance.   The wastewater treatment apparatus according to claim 5 or 6, wherein the solid-liquid separation means and the second solid-liquid separation means are filters, and contain an organic oxygen scavenger and a suspended substance. Wastewater treatment equipment. The wastewater treatment apparatus according to any one of claims 5 to 7, wherein the inorganic flocculant includes at least one of an aluminum salt and a ferric salt, and the oxidizing agent is hypochlorous acid. A wastewater treatment apparatus containing an organic oxygen scavenger and a suspended substance, characterized by comprising an acid sodium solution.

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