JP2010240587A - Wastewater treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus which cleans a harmful wastewater containing heavy metals, fluorine and an organic material and makes the waste water harmless to such a state that the waste water can be discharged. <P>SOLUTION: The pH of a floatation wastewater W3 generated when floatation of a slurry S1 containing Cl bypass dust is carried out, is adjusted to about 8.0-12.0, and heavy metals contained in the wastewater W3 etc. are precipitated. Fluorine in a slurry S2 in which heavy metals are precipitated, is precipitated, and solid matters in a slurry S3 in which heavy metals and fluorine are precipitated, are removed by a solid-liquid separator 12. A filtrate W4 in the solid-liquid separator 12 is secondarily filtrated with a sand filter 14. An oxidant is added, in an organic matter treatment tank 16, to a filtrate W5 after the heavy metals are adsorption removed in a chelate resin tower 15, to decompose the organic compound in the filtrate W5. Selenium as well as heavy metals is also precipitated and removed. Wastewater generated when floatation of the slurry of dust is carried out, waste water generated when floatation of the slurry of contaminated soil is carried out, and the like are also made to be harmless by the wastewater treatment method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wastewater treatment method for purifying harmful wastewater, and more particularly, to a method for removing the heavy metals, selenium, fluorine and organic substances in the wastewater and detoxifying the wastewater.

  Focusing on chlorine, sulfur, alkali, etc., which causes problems such as blockage of preheaters in cement manufacturing facilities, from the bottom of the kiln of the cement kiln to the bottom cyclone A chlorine bypass system for extracting a part of combustion gas and removing chlorine from the kiln exhaust gas flow path is used.

  In this chlorine bypass system, chlorine is unevenly distributed on the fine powder side of the dust generated by cooling the extracted combustion gas, so the dust is separated into coarse powder and fine powder by a classifier, and the coarse powder is converted into a cement kiln system. At the same time, the fine powder (chlorine bypass dust) containing the separated potassium chloride and the like was recovered.

  However, the extracted combustion gas contains heavy metals such as lead and cadmium, selenium, fluorine, etc. in addition to chlorine, etc., and when the recovered chlorine bypass dust is discarded or returned to the raw material system. In any case, it is necessary to handle appropriately.

  Therefore, in Patent Document 1, in order to remove lead from chlorine bypass dust, water and sulfuric acid are mixed with chlorine bypass dust to adjust the liquidity to pH 1 to 4, and after producing a slurry containing calcium sulfate, There has been proposed a method in which a sulfide is added to a slurry to produce lead sulfide, and then a collector is added to the slurry to perform flotation, and lead sulfide is floated and recovered.

  Further, in Patent Document 2, for the same purpose as described above, chlorine bypass dust is mixed with water and sulfuric acid to adjust the liquidity to pH 4 or less, and after producing a slurry containing calcium sulfate and lead sulfate, the slurry There has been proposed a method in which an alkali agent is added to adjust the liquidity to pH 5 or higher, and then a trapping agent or the like is added to the slurry to perform flotation, and lead sulfate is precipitated to be recovered.

JP 2006-346512 A JP 2006-299394 A

  According to the processing methods described in Patent Documents 1 and 2, lead contained in the chlorine bypass dust can be effectively removed, but some of the heavy metals that could not be completely removed are subjected to flotation. It remains in the discharged wastewater. On the other hand, in recent years, recycling of waste by converting to cement raw material or fuel has been promoted, and as the amount of waste processed increases, the amount of heavy metals such as lead, selenium, and fluorine brought into the cement kiln also increases. ing.

  In the above processing method, as a pretreatment for flotation, a hydrophobizing agent (eg, xanthate) or the like as a collecting agent is added to the slurry, and the organic compound such as the hydrophobizing agent is added during the flotation. However, when the wastewater is discharged, it is also required to remove these components.

  These problems are not limited to the flotation drainage generated when flotation of chlorine bypass dust slurry, but also occur when flotation of polluted soil slurry or drainage generated when flotation of soot and dust slurry. In the case of drainage, etc., it occurs almost in the same way, and it is necessary to appropriately detoxify it.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and purifies harmful wastewater containing heavy metals, selenium, fluorine and organic matter, so that the wastewater can be discharged. It aims at providing the waste water treatment method which can be detoxified.

  In order to achieve the above object, the present invention is a wastewater treatment method for purifying wastewater containing heavy metals, fluorine and organic matter, and is included in the wastewater by adjusting the pH of the wastewater to a predetermined value. A heavy metal precipitation treatment step for precipitating heavy metals, a fluorine precipitation treatment step for precipitating fluorine in the wastewater from which the heavy metals have precipitated, and a solid content in the wastewater from which the heavy metals and fluorine have been precipitated are removed. A solid-liquid separation step for removing heavy metals and fluorine by adding an oxidizing agent to the waste water from which the heavy metals and fluorine have been removed, and an organic matter treatment step for oxidizing the organic matter in the waste water. And

  According to the present invention, it is possible to remove heavy metals, fluorine, and organic compounds contained in wastewater, and it is possible to render the wastewater harmless to a state where it can be discharged.

  Further, the present invention is a wastewater treatment method for purifying wastewater containing heavy metals, selenium, fluorine and organic matter, and adjusting the pH of the wastewater to a predetermined value, Heavy metals that precipitate selenium and selenium precipitation treatment step, fluorine precipitation treatment step that precipitates fluorine in wastewater in which the heavy metals and selenium are precipitated, and wastewater in which the heavy metals, selenium, and fluorine are precipitated. A solid-liquid separation process for removing heavy metals, selenium and fluorine by removing solids of the product, and an oxidizing agent is added to the waste water from which the heavy metals, selenium and fluorine have been removed, and the organic matter in the waste water is oxidized. And an organic matter treatment step.

  According to the present invention, it is possible to remove heavy metals, selenium, fluorine and organic compounds contained in the waste water, and it is possible to render the waste water harmless to a state where it can be discharged.

  In the wastewater treatment method, in the heavy metals precipitation treatment step or the heavy metals and selenium precipitation treatment step, the pH of the wastewater can be adjusted to 8.0 or more and 12.0 or less, It becomes possible to effectively precipitate heavy metals contained in the waste water.

In the wastewater treatment method, in the heavy metal precipitation treatment step or the heavy metals and selenium precipitation treatment step, wastewater containing the heavy metals, fluorine and organic matter, or the heavy metals, selenium, fluorine and organic matter is contained. Metallic iron or / and ferrous compound can be added to wastewater, and by adding metallic iron or / and ferrous compound, arsenic and hexavalent chromium are precipitated simultaneously with heavy metals and selenium. can do. Here, the ferrous compound can be at least one selected from the group consisting of ferrous chloride (FeCl ₂ ), ferrous sulfate (FeSO ₄ ), and ferrous nitrate (FeNO ₃ ). .

  Further, in the wastewater treatment method, in the fluorine precipitation treatment step, the pH of the wastewater can be adjusted to 9.0 or more and 12.0 or less, and according to this, fluorine contained in the wastewater is effectively removed. It becomes possible to precipitate.

In the wastewater treatment method, the oxidizing agent is at least one selected from the group consisting of hydrogen peroxide (H ₂ O ₂ ), sodium hypochlorite (NaClO), ozone (O ₃ ), and oxygen (O ₂ ). Seeds can be used.

  In the wastewater treatment method, secondary filtration of the filtrate discharged in the solid-liquid separation step and / or adsorption removal of heavy metals in the filtrate discharged in the solid-liquid separation can be performed. According to this, heavy metals that could not be completely removed by solid-liquid separation can be removed, and it becomes possible to further purify the waste water.

  As one embodiment of the above-mentioned wastewater treatment method, as a wastewater containing the heavy metals, fluorine and organic matter, or as a wastewater containing the heavy metals, selenium, fluorine and organic matter, a flotation wastewater generated when flotation is performed Can be processed.

  As one embodiment of the wastewater treatment method, the flotation wastewater is slurried dust contained in the combustion gas extracted from the kiln exhaust gas flow path from the bottom of the cement kiln to the bottom cyclone, the slurry Flotation wastewater generated when flotation is performed on a substance to which a collector is added can be treated.

  As described above, according to the present invention, it is possible to purify harmful wastewater containing heavy metals, selenium, fluorine and organic matter and render it harmless to a state where the wastewater can be discharged.

It is a flowchart which shows 1st Embodiment of the system to which the waste water treatment method concerning this invention is applied. It is a flowchart which shows 2nd Embodiment of the system to which the waste water treatment method concerning this invention is applied. It is a graph which shows the relationship between the addition amount of 35% hydrogen peroxide water in organic substance processing, and iodine consumption.

  Next, an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a first embodiment of a system to which a wastewater treatment method according to the present invention is applied. This wastewater treatment system 1 is roughly composed of a lead recovery facility 2 and a wastewater treatment facility 3.

  The lead recovery facility 2 is a facility for recovering lead in dust (chlorine bypass dust) contained in the combustion gas extracted from the kiln exhaust gas passage from the kiln bottom of the cement kiln to the bottom cyclone. Pretreatment equipment 4 for performing pH adjustment, sulfidation, addition of a collecting agent, and the like, and slurry S1 supplied from the pretreatment equipment 4 are subjected to flotation, and lead sulfide is removed from the slurry S1. It comprises a flotation equipment 5 for separation and solid-liquid separators 6 and 7 for separating the floss F and tail T collected by the flotation equipment 5 from each other.

The pretreatment facility 4 adds lead sulfide to the slurryed chlorine bypass dust to produce lead sulfide, and adds sulfuric acid to react with calcium in the slurry to produce calcium sulfate. It is provided for adding agents and foaming agents. As the sulfiding agent, sodium hydrosulfide (NaSH), sodium sulfide (Na ₂ S), hydrogen sulfide gas (H ₂ S), or the like can be used.

  In addition, as a collecting agent, xanthate, acidic dithiophosphates (trade name: Elofloat), alkyl sulfates such as sodium n-dodecyl sulfate, unsaturated aliphatic carboxylates such as sodium oleate, etc. should be used. Can do.

  Furthermore, as a foaming agent, methyl isobutyl carbinol (MIBC; 4-methyl-2-pentanol), methyl isobutyl ketone, pine oil, ethylene glycol, propylene glycol methyl ether, cresolic acid, or the like can be used.

  The flotation equipment 5 is provided for flotation of the slurry S1 supplied from the pretreatment equipment 4 and separating lead sulfide from the slurry S1. In the flotation beneficiation equipment 5, the lead sulfide in the slurry S <b> 1 adheres to the bubbles generated inside and floats, and is recovered as floss F. The calcium sulfate in the slurry S1 settles at the bottom of the liquid in the flotation equipment 5 and is discharged together with the tail T.

  The solid-liquid separator 6 is provided for solid-liquid separation of the floss F collected by the flotation equipment 5, and separates the floss F into a cake C1 and a filtrate W1. The solid-liquid separator 7 is provided for solid-liquid separation of the tail T supplied from the flotation beneficiation equipment 5, and separates the tail T into cake C2 and filtrate W2.

  The wastewater treatment facility 3 is a facility for detoxifying the industrial wastewater generated in the lead recovery facility 2. The heavy metal precipitation tank 10, the fluorine precipitation tank 11, the solid-liquid separator 12, the adjustment tank 13, , A sand filter 14, a chelate resin tower 15, and an organic matter treatment tank 16.

  The heavy metal precipitation tank 10 is added to the filtrate (floating beneficiation wastewater) W3 (W1 + W2) discharged from the solid-liquid separators 6 and 7, adjusts the pH of the filtrate W3, and is contained in the filtrate W3. Provided for precipitating heavy metals. In addition, as an alkali agent, slaked lime slurry, caustic soda, sodium carbonate, etc. can be used, These 1 type may be used independently and 2 or more types may be used together.

  The fluorine precipitation tank 11 is provided for adding a magnesium compound to the slurry S2 discharged from the heavy metal precipitation tank 10 and adjusting the pH in the fluorine precipitation tank 11 to precipitate fluorine contained in the slurry S2. It is done. In addition, as a magnesium compound, 1 or more types selected from magnesium chloride, magnesium oxide, magnesium sulfate, magnesium carbonate, magnesium nitrate, and magnesium hydroxide can be used. At this time, sodium hydroxide, potassium hydroxide, calcium hydroxide, or the like can be used as a pH adjuster. In particular, when sodium hydroxide, potassium hydroxide, or both are used, There is an advantage that scale does not easily occur.

  The solid-liquid separator 12 is provided for solid-liquid separation of the slurry S3 generated in the fluorine precipitation tank 11 and recovering heavy metals and fluorine precipitated in the slurry S2. The cake C3 generated by the solid-liquid separator 12 is reused as a cement raw material or the like.

  The adjustment tank 13 is provided for adding hydrochloric acid to the filtrate W4 discharged from the solid-liquid separator 12 and adjusting the pH of the filtrate W4 to 4-6. The filtrate W4 whose pH is adjusted is secondarily filtered by the sand filter 14, and then the heavy metal is adsorbed and removed by the chelate resin in the chelate resin tower 15 to purify the filtrate W4.

The organic matter treatment tank 16 is provided to add an oxidizing agent to the filtrate W5 purified by the sand filter 14 and the chelate resin tower 15 and oxidize organic compounds dissolved in the filtrate W5. As the oxidizing agent, hydrogen peroxide water (H ₂ O ₂ ), sodium hypochlorite (NaClO), ozone (O ₃ ), oxygen (O ₂ ), etc. can be used, and one of these can be used alone. You may use, and may use 2 or more types together.

  Next, the waste water treatment method according to the present invention will be described with reference to FIG.

  Chlorine bypass dust is supplied to the pretreatment facility 4 and mixed with water to produce a slurry, and then a sulfiding agent and sulfuric acid are added to produce lead sulfide and calcium sulfate. Next, a hydrophobizing agent as a collecting agent and a foaming agent are added to the slurry.

  Next, the slurry S1 from the pretreatment facility 4 is supplied to the flotation beneficiation facility 5, and bubbles are generated in the flotation beneficiation facility 5, and lead sulfide in the slurry S1 is adhered to the bubbles. Thereafter, the air bubbles floating together with the lead sulfide are recovered, and the recovered froth F is supplied to the solid-liquid separator 6. The calcium sulfate contained in the slurry S1 settles without adhering to the bubbles and is supplied to the solid-liquid separator 7 together with the tail T.

  Next, the solid-liquid separator 6 performs solid-liquid separation of the froth F from the flotation equipment 5 to recover lead sulfide. Since the dehydrated lead sulfide has a low content of components other than lead sulfide, it is reused as a non-ferrous refining raw material by Yamamoto reduction.

  At the same time, the tail T from the flotation equipment 5 is solid-liquid separated by the solid-liquid separator 7 and calcium sulfate is recovered as gypsum. The collected gypsum is reused by adding it to a cement mill or the like.

  Next, the filtrate W3 of the solid-liquid separators 6 and 7 is supplied to the heavy metal precipitation tank 10, and in the heavy metal precipitation tank 10, an alkaline agent such as slaked lime slurry is added to the filtrate W3. The pH of the inner slurry S2 is adjusted to precipitate heavy metals. At this time, the pH of the slurry S2 is preferably adjusted to 8.0 to 12.0.

  Next, the slurry S2 of the heavy metal precipitation tank 10 is supplied to the fluorine precipitation tank 11, and the magnesium compound is added to the fluorine precipitation tank 11, and the pH in the fluorine precipitation tank 11 is adjusted, and the fluorine contained in the slurry S2 is added. To precipitate. For example, magnesium hydroxide can be added to precipitate fluorine by coprecipitation. At this time, the pH of the slurry S3 in the fluorine precipitation tank 11 is preferably adjusted to 9.0 to 12.0. In addition, since pH adjustment has already been performed in the heavy metal precipitation tank 10, even if a magnesium compound is added in the fluorine precipitation tank 11, the pH of the slurry S3 in the fluorine precipitation tank 11 is in the range of 9.0 to 12.0. In this case, pH adjustment in the fluorine precipitation tank 11 is not necessary.

  Next, the slurry S3 is supplied from the fluorine precipitation tank 11 to the solid-liquid separator 12, and the slurry S3 is subjected to solid-liquid separation. And slurry S3 is isolate | separated into the filtrate W4 and the cake C3, and the isolate | separated cake C3 is collect | recovered. Thus, heavy metals and fluorine in the slurry S2, that is, heavy metals and fluorine remaining in the flotation wastewater W3 of the flotation equipment 5 are recovered.

  Next, the filtrate W4 of the solid-liquid separator 12 is supplied to the adjustment tank 13, and hydrochloric acid as a neutralizing agent is added to the filtrate W4 in the adjustment tank 13, so that the pH of the filtrate W4 is 4-6. adjust. Thereafter, the pH-adjusted filtrate W4 is supplied to the sand filter 14 for secondary filtration, and the chelate resin tower 15 adsorbs and removes heavy metals remaining in the filtrate W4.

  Next, the filtrate W5 from which heavy metals have been removed is supplied to the organic matter treatment tank 16, and in the organic matter treatment tank 16, hydrochloric acid is added to the filtrate W5 to adjust the pH of the filtrate W5 to 2-4. Thereafter, an oxidizing agent such as hydrogen peroxide is added to the filtrate W5 whose pH has been adjusted, and the organic compound dissolved in the filtrate W5 is oxidized and decomposed. At this time, for example, when 35% hydrogen peroxide is used as the oxidizing agent, the amount added is 0.5 to 2 ml / l with respect to 1 liter of the filtrate W5 in consideration of the chemical cost and the like. Is preferred.

  Finally, caustic soda (NaOH) is added to the filtrate W5 in which the organic compound has been decomposed, and the pH of the filtrate W5 is adjusted to the neutral range of 6-8. The pH-adjusted filtrate W6 can be discharged into the sewer.

  As described above, according to the present embodiment, heavy metal and fluorine are separated by solid-liquid separation after the filtrate W3 discharged from the lead recovery facility 2 is subjected to heavy metal precipitation treatment and fluorine precipitation treatment. Is added to the filtrate W5 from which heavy metals and fluorine have been removed, and the organic compound in the filtrate W5 is decomposed, so that it is contained in the flotation wastewater W3 when the chlorine bypass dust is treated. Heavy metals, fluorine and organic compounds can be removed, and the waste water W3 can be rendered harmless to a state where it can be discharged.

In addition, arsenic and hexavalent chromium can be precipitated simultaneously with heavy metals by adding metallic iron, a ferrous compound, etc. as a reducing agent to the heavy metal precipitation tank 10 of the said embodiment. Here, ferrous chloride (FeCl ₂ ), ferrous sulfate (FeSO ₄ ), ferrous nitrate (FeNO ₃ ), and the like can be used as the ferrous compound.

  In the above embodiment, coprecipitation with magnesium hydroxide or the like is used in the fluorine precipitation tank 11 to precipitate fluorine contained in the slurry S2 discharged from the heavy metal precipitation tank 10. In addition, precipitation by the formation of fluoroapatite and precipitation by addition of a calcium compound can also be used.

  In the case of producing fluorapatite, phosphoric acid and a calcium compound are added to the slurry S2, and the pH of the slurry S2 is adjusted to about 9.0 to 12.0. Examples of the pH adjuster used at this time include sodium hydroxide, potassium hydroxide, and calcium hydroxide. When calcium hydroxide slurry is used as a pH adjuster, calcium can be added simultaneously with pH adjustment.

  On the other hand, in the case of precipitation by the addition of a calcium compound, the calcium compound is added and the pH in the fluorine precipitation tank 11 is adjusted to precipitate fluorine contained in the slurry S2. In addition, as a calcium compound, calcium chloride, calcium carbonate, calcium oxide, calcium hydroxide, etc. can be used, These 1 type may be used independently and 2 or more types may be used together. When calcium oxide, calcium hydroxide, or both are used, pH adjustment can be performed simultaneously. When a calcium compound other than calcium oxide and calcium hydroxide is used, an alkaline agent such as caustic soda can be used as in the heavy metal precipitation tank 10.

  Moreover, in the said embodiment, after adding the alkaline agent to the filtrate W3, the heavy metals which precipitated were removed, but when the density | concentration of the heavy metals in the filtrate W3 is low, it replaces with these operation. Heavy metals can be adsorbed and removed by the chelate resin.

Further, ferric chloride (FeCl ₃ ), sulfuric acid band (aluminum sulfate, Al ₂ (SO ₄ ) ₃ ), sodium hydrosulfide (NaSH), etc., which are generally used in wastewater treatment when the filtrate W3 is treated. A flocculant or a liquid chelating agent can also be used.

  Next, a second embodiment of the system to which the wastewater treatment method according to the present invention is applied will be described with reference to FIG. In addition, in the figure, the same code | symbol is attached | subjected about the component same as the waste water treatment system 1 shown in FIG. 1, and the description is abbreviate | omitted. The lead recovery facility is the same as the lead recovery facility 2 of FIG.

  The waste water treatment system 20 shown in FIG. 2 has a basic configuration substantially the same as that of the waste water treatment system 1 shown in FIG. 1, and is different in that the waste water treatment facility 3 includes an adjustment tank 21.

  The adjustment tank 21 is disposed on the upstream side of the heavy metal precipitation tank 10 and is provided to remove selenium contained in the filtrate W3 from the solid-liquid separators 6 and 7 (see FIG. 1). In the adjustment tank 21, first, hydrochloric acid is added to the filtrate W3 to make it acidic. At this time, the pH of the filtrate W3 is preferably adjusted to 4.5 or less, more preferably 4.0 or less. Next, a reducing agent is added to the adjustment tank 21. By performing the above operation, when the pH of the filtrate W3 is subsequently increased in the heavy metal precipitation tank 10, a coprecipitate of ferrous hydroxide and selenium can be generated satisfactorily. The amount of ferrous compound added can be greatly reduced.

  The produced coprecipitate of ferrous hydroxide and selenium is separated from the slurry S3 by solid-liquid separation in the solid-liquid separator 12, thereby removing selenium contained in the flotation wastewater W3.

  According to the wastewater treatment system 20, selenium contained in the flotation wastewater W3 when chlorine bypass dust is treated can be removed, and even if the wastewater W3 contains a large amount of selenium, Can be reduced below the discharge standard value.

  Hereinafter, the present invention will be described more specifically with reference to examples.

  Using the wastewater treatment system 1 of FIG. 1, the chlorine bypass dust is treated while adjusting the pH of the slurry S2 in the heavy metal precipitation tank 10 to 10.5 and the pH of the slurry S3 in the fluorine precipitation tank 11 to 10.5. At that time, the filtrate W4 (treated wastewater) of the solid-liquid separator 12 was analyzed. In addition, the filtrate W3 (pretreatment waste water) upstream of the heavy metal precipitation tank 10 was also analyzed.

  The analysis results are shown in Table 1. Here, each numerical value in Table 1 indicates the amount of heavy metals per liter of solution, and the unit is mg / l. As shown in Table 1, it was found that metals, heavy metals and fluorine in the filtrate W3 can be removed reliably.

  Next, chlorine bypass dust having a high selenium content is treated using the wastewater treatment system 20 of FIG. 2 and discharged from the filtrate W3 (pretreatment wastewater) upstream of the adjustment tank 21 and the organic matter treatment tank 16. The filtrate W6 (drained water after treatment) was analyzed. Moreover, in the organic substance processing tank 16, the oxidizing agent was added, the organic compound was oxidized, and the iodine consumption in the filtrate W6 was measured.

  Here, the pH of the slurry S2 in the adjustment tank 21 was adjusted to 9.0, and the pH of the filtrate W5 in the organic matter treatment tank 16 was adjusted to 3.0. Further, hydrogen peroxide water was used as an oxidizing agent in the organic matter treatment tank 16. The analysis results of the filtrates W3 and W6 are shown in Table 2, and the measurement results of iodine consumption are shown in Table 3. In addition, the unit of the analysis value etc. in both tables is mg / l.

  As shown in Table 2, lead (Pb), zinc (Zn), and selenium (Se) were detected in the filtrate W6 after the oxidation treatment, and all of them were 1/10 or less of the discharge standard value. It was confirmed that the amount of the waste water W3 from the lead recovery facility 2 can be made harmless by a small amount.

  Further, as shown in Table 3, it was confirmed that the iodine consumption in the filtrate W6 after the oxidation treatment (treated wastewater) was significantly lower than the legal standard value and there was no problem from the environmental aspect.

  Next, the organic compound in the filtrate W5 was processed using the wastewater treatment system 20 of FIG. 2 while adjusting the amount of the oxidizing agent. Here, 35% hydrogen peroxide water was used as the oxidizing agent. The relationship between the addition amount of 35% hydrogen peroxide water and the iodine consumption amount in the waste water W6 is shown in FIG.

  As shown in FIG. 3, when 35% hydrogen peroxide solution is not used, the iodine consumption is about 1100 mg / l, whereas to make the iodine consumption 0 mg / l, about 1.3 ml / L of 35% hydrogen peroxide solution was found to be required. Taking into account the release standard value of iodine consumption, it was found that an addition amount of 35% hydrogen peroxide water of 0.7 ml / l or more is preferable. Each value in FIG. 3 varies depending on the chlorine bypass dust to be treated and the conditions of the flotation treatment, etc., and the figure shows an optimum collecting agent for efficiently recovering lead from a certain chlorine bypass dust. It is the test example about the waste_water | drain at the time of setting it as the addition amount of a foaming agent.

DESCRIPTION OF SYMBOLS 1 Wastewater treatment system 2 Lead recovery equipment 3 Wastewater treatment equipment 4 Pretreatment equipment 5 Flotation equipment 6 Solid-liquid separator 7 Solid-liquid separator 10 Heavy metal precipitation tank 11 Fluorine precipitation tank 12 Solid-liquid separator 13 Adjustment tank 14 Sand filtration 15 Chelate resin tower 16 Organic matter treatment tank 20 Wastewater treatment system 21 Adjustment tank

Claims (10)

A wastewater treatment method for purifying wastewater containing heavy metals, fluorine and organic matter,
A heavy metal precipitation treatment step for precipitating heavy metals contained in the waste water by adjusting the pH of the waste water to a predetermined value;
A fluorine precipitation treatment step for precipitating fluorine in the wastewater from which the heavy metals have been precipitated;
A solid-liquid separation step of removing heavy metals and fluorine by removing solids in the waste water in which the heavy metals and fluorine are precipitated;
A wastewater treatment method comprising: adding an oxidant to the wastewater from which the heavy metals and fluorine have been removed, and oxidizing an organic matter in the wastewater. A wastewater treatment method for purifying wastewater containing heavy metals, selenium, fluorine and organic matter,
Adjusting the pH of the waste water to a predetermined value, thereby precipitating heavy metals and selenium contained in the waste water, and a selenium precipitation treatment step;
A fluorine precipitation treatment step for precipitating fluorine in the waste water in which the heavy metals and selenium are precipitated;
A solid-liquid separation step of removing heavy metals, selenium and fluorine by removing solids in the waste water in which the heavy metals, selenium and fluorine are precipitated;
A wastewater treatment method comprising: an organic matter treatment step of adding an oxidizing agent to the wastewater from which the heavy metals, selenium and fluorine have been removed, and oxidizing the organic matter in the wastewater.   The wastewater treatment according to claim 1 or 2, wherein in the heavy metal precipitation treatment step or the heavy metals and selenium precipitation treatment step, the pH of the wastewater is adjusted to 8.0 or more and 12.0 or less. Method   In the heavy metal precipitation treatment step or the heavy metal and selenium precipitation treatment step, for the waste water containing the heavy metals, fluorine and organic matter, or for the waste water containing the heavy metals, selenium, fluorine and organic matter, metallic iron 4. A wastewater treatment method according to claim 1, 2 or 3, wherein ferrous compounds are added. The ferrous compound is at least one selected from the group consisting of ferrous chloride (FeCl ₂ ), ferrous sulfate (FeSO ₄ ), and ferrous nitrate (FeNO ₃ ). Item 5. A wastewater treatment method according to Item 4.   The wastewater treatment method according to any one of claims 1 to 5, wherein, in the fluorine precipitation treatment step, the pH of the wastewater is adjusted to 9.0 or more and 12.0 or less. The oxidizing agent is at least one selected from the group consisting of hydrogen peroxide (H ₂ O ₂ ), sodium hypochlorite (NaClO), ozone (O ₃ ), and oxygen (O ₂ ). The waste water treatment method according to any one of claims 1 to 6.   The secondary filtration of the filtrate discharged | emitted in the said solid-liquid separation process and / or the adsorption removal of the heavy metals in the filtrate discharged | emitted by the said solid-liquid separation are performed. The waste water treatment method of crab.   9. The wastewater containing heavy metals, fluorine and organic matter, or the wastewater containing heavy metals, selenium, fluorine and organic matter is a flotation wastewater generated when flotation is performed. The waste water treatment method in any one of.   The flotation wastewater slurried dust contained in the combustion gas extracted from the kiln exhaust gas flow path from the kiln bottom of the cement kiln to the bottom cyclone, and flotated the substance added with a collector to the slurry The wastewater treatment method according to claim 9, wherein the wastewater treatment is a flotation wastewater generated at a time.

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