JP4182860B2 - Muddy water treatment method - Google Patents

Description

  The present invention relates to a muddy water treatment method, and more particularly to a muddy water treatment method including a step of separating muddy water into a liquid phase and a solid phase.

  Mud water generated by dredging the bottom of lakes and harbors, muddy water containing activated sludge and paper sludge, waste incinerator demolition residue and muddy water generated during soil cleaning are persistent organic pollution such as dioxins. It may contain harmful organic substances such as substances and organometallic compounds. For this reason, it is necessary to treat the mud water as described above so as not to cause secondary contamination. We are removing organic substances.

  Here, the organic substance is usually removed from the liquid phase by a method of removing the organic substance by subjecting the liquid phase to membrane separation treatment and then activated carbon treatment (Patent Document 1), or by applying ozone to the liquid phase under irradiation of ultraviolet rays. A method of oxidatively decomposing an organic substance by supplying (Patent Document 2) or the like is employed. However, these methods may make it difficult to effectively remove organic substances due to the water quality of the liquid phase. For example, in the case of the method described in Patent Document 1, the separation membrane is easily clogged as the turbidity of the liquid phase increases, and the adsorptive capacity of activated carbon decreases, so that organic substances contained in the liquid phase are removed. It becomes difficult. Further, according to the method described in Patent Document 2, as the turbidity of the liquid phase increases, the irradiation efficiency of ultraviolet rays on the organic substance decreases, and the organic substance becomes difficult to be oxidatively decomposed.

  In addition, the treatment of muddy water as described above is often performed at a site where muddy water is generated because it is highly necessary to reduce the cost required for transporting and transporting muddy water and to suppress the entire treatment cost. In this case, facilities for carrying out the above-mentioned methods used for the treatment of the liquid phase need to secure large-scale equipment with a treatment capacity capable of handling the maximum amount of muddy water, and these facilities Is complicated, installation, adjustment and removal work is complicated, and implementation costs and maintenance costs are high.

JP 2000-210663 A

Japanese Patent No. 2874126

  An object of the present invention is to easily obtain a liquid phase from which organic substances are removed from muddy water.

The muddy water treatment method according to the present invention includes a separation step of separating muddy water into a liquid phase and a solid phase, an addition step of adding a water-soluble carbon material and a flocculant to the liquid phase, and removing precipitates from the liquid phase. And a carbon material containing an inorganic material having a carboxyl group or a hydroxyl group as a water-soluble carbon material .

  In this processing method, the organic substance contained in the liquid phase obtained in the separation step is adsorbed by the water-soluble carbon material added to the liquid phase. And the water-soluble carbon material which adsorb | sucked the organic substance turns into an aggregate in a liquid phase by the effect | action of the added flocculant. Therefore, when the aggregate is removed from the liquid phase, a liquid phase from which organic substances have been removed is obtained.

  This processing method usually further includes a step of mixing the solid phase and the aggregate.

The method for treating muddy water according to another aspect of the present invention includes a first addition step in which a water-soluble carbon material and a flocculant are added to the muddy water, and muddy water after the first addition step. And a carbon material containing an inorganic material having a carboxyl group or a hydroxyl group as a water-soluble carbon material.

  In this treatment method, the organic substance contained in the muddy water is adsorbed by the water-soluble carbon material added to the muddy water in the first addition step. And the water-soluble carbon material which adsorb | sucked the organic substance turns into an aggregate in muddy water by the effect | action of the added flocculant. Therefore, when the muddy water after the first addition step is separated into the first liquid phase and the first solid phase, the first liquid phase from which the organic substance has been removed is obtained.

The muddy water treatment method according to still another aspect of the present invention includes a first addition step of adding a water-soluble carbon material and a flocculant to the muddy water, and the muddy water after the first addition step, the first liquid phase and the first solid phase. A first separation step for separating the first liquid phase, a second addition step for further adding a water-soluble carbon material and an aggregating agent to the first liquid phase, a first liquid phase after the second addition step, and a second liquid phase A carbon material containing a carbon material that has been surface-modified by introduction of a carboxyl group or a hydroxyl group as a water-soluble carbon material or an inorganic material having a carboxyl group or a hydroxyl group. Is used. This processing method usually further includes a step of mixing the first solid phase and the second solid phase.

  In the method for treating muddy water according to the present invention, a water-soluble carbon material and a flocculant are added to a liquid phase obtained by separating muddy water into a liquid phase and a solid phase, and aggregates are further removed from the liquid phase. Therefore, a liquid phase from which organic substances are removed can be easily obtained from the muddy water.

  Further, in the method for treating muddy water according to another aspect of the present invention, the muddy water is separated into a liquid phase and a solid phase after adding the water-soluble carbon material and the flocculant to the muddy water. A liquid phase from which substances have been removed can be easily obtained.

  The muddy water to which the muddy water treatment method according to the present invention is applicable is not particularly limited. For example, muddy water containing dredged mud water, activated sludge and paper sludge generated when dredging the bottom sediment of lakes and harbors. , Waste incinerator demolition residue and muddy water generated during soil cleaning.

Form 1
With reference to FIG. 1, Embodiment 1 of the muddy water processing method which concerns on this invention is demonstrated. FIG. 1 is a schematic view of a treatment apparatus for carrying out the muddy water treatment method according to this embodiment. The treatment apparatus 1 mainly includes a supply device 2, a solid-liquid separation device 3, a chemical addition device 4, and a filter press 5. In preparation.

  The supply device 2 is for supplying muddy water to be processed to the solid-liquid separation device 3. The solid-liquid separation device 3 is for separating the muddy water supplied from the supply device 2 into solids (ie, solid phase) such as sand, earth and sand, and sludge, and moisture (ie, liquid phase), The separated water is set to be able to be supplied to the drug addition device 4, and the separated solid content is set to be able to be supplied to the filter press 5.

  The drug addition device 4 mainly includes a storage tank 6 for storing water from the solid-liquid separation device 3 and a drug injection device 7. The storage tank 6 includes a discharge path 8 having a pump (not shown) for discharging moisture to the outside. Moreover, the bottom part of the storage tank 6 has the discharge part 9 which can take out the aggregate mentioned later. On the other hand, the chemical injection device 7 is for supplying chemicals to the water stored in the storage tank 6, and has a first chemical injection device 10 and a second chemical injection device 11. Each of the drug injectors 10 and 11 includes a storage unit (not shown) for storing a drug, and a pump (not shown) for supplying the drug stored in the storage unit to the storage tank 6. It has. In addition, the chemical | medical agent supplied to the storage tank 6 from the 1st chemical injection device 10 and the chemical | medical agent supplied to the storage tank 6 from the 2nd chemical injection device 11 are mentioned later.

  The filter press 5 is for pressurizing the solid content from the solid-liquid separation device 3 to dehydrate the water remaining in the solid content, and for supplying the dehydrated water to the storage tank 6. It has a path 12.

  Next, the chemical | medical agent supplied with respect to the storage tank 6 from the 1st chemical injection device 10 is demonstrated. This drug is a water-soluble carbon material, has an adsorptivity of organic substances, and is dissolved or dispersed in water, for example, in the form of colloidal particles. As such a water-soluble carbon material, for example, a carbon material whose surface is modified by introduction of a carboxyl group or a hydroxyl group, or a carbon material including an inorganic material having a carboxyl group or a hydroxyl group can be used.

  However, the water-soluble carbon material preferably has a dispersion rate in water of 30% or more, and more preferably 40% or more. Here, the dispersion rate of the water-soluble carbon material can be determined as follows. First, a predetermined amount of water-soluble carbon material is added to a predetermined amount of water to prepare a dispersion. Then, the dispersion is centrifuged at 10,000 G for 15 minutes, and then the precipitated water-soluble carbon material is separated and its weight is measured. The target dispersion ratio can be obtained from the following equation (1). In the formula (1), A represents the total weight of the water-soluble carbon material added in water, and B represents the weight of the precipitated water-soluble carbon material.

  Examples of the water-soluble carbon material having a dispersion rate of 30% or more in water include water-soluble polynuclear aromatic compounds obtained by oxidative decomposition of carbonaceous substances. Such a water-soluble polynuclear aromatic compound can be produced, for example, as follows. First, the carbonaceous material is oxidatively decomposed. Examples of the carbonaceous material used here include carbon black, coke, pitch, coal, and activated carbon. These carbonaceous materials may be used alone or in combination of two or more. Moreover, the oxidative decomposition method of the carbonaceous material is not particularly limited. For example, a method of oxidizing the carbonaceous material using an oxidizing agent such as nitric acid, air, hydrogen peroxide or ozone is adopted. Can do. The oxidative decomposition of the carbonaceous material is preferably carried out until an oxidative decomposition product corresponding to a molecular weight of 3,000 to 100,000 is obtained.

  Next, the reaction mixture after the oxidative decomposition is made basic by adding an alkali, and then a fraction having a molecular diameter within a predetermined range is collected by a filtration technique such as ultrafiltration. Aromatic compounds are obtained. The fraction to be fractionated here preferably has a molecular diameter in the range of 1 to 10 nm. When the molecular diameter is less than 1 nm, handling becomes difficult, and the adsorptivity of organic substances may be reduced. Further, when the molecular diameter exceeds 10 nm, it is difficult to dissolve in the water to be treated (that is, the above-mentioned dispersion rate may be reduced), and the adsorptivity of the organic substance may be reduced to the level of activated carbon. There is.

  The water-soluble polynuclear aromatic compounds as described above have a special plate-like structure in which the periphery of the hydrophobic polynuclear aromatic condensed ring is surrounded by hydrophilic functional groups such as carboxyl groups and hydroxyl groups, carbonyl groups and nitro groups. Therefore, it is easily dissolved in water, particularly in water having a pH range of weakly acidic or higher. In addition, since this water-soluble polynuclear aromatic compound has the property of being able to adsorb inorganic cations such as heavy metal ions contained in the water to be treated by ion exchange, it is negatively charged when dissolved in water. May be present as a suspended substance.

  The water-soluble polynuclear aromatic compound as described above is a substance already known in Japanese Patent No. 3079260.

  Examples of other water-soluble carbon materials having a dispersion rate in water of 30% or more include carbon black adsorbed with humic acids. Such carbon black can be produced, for example, by surface-treating carbon black with an aqueous solution in which humic acids are dissolved. The surface treatment method here is performed, for example, by wet granulating carbon black powder with an aqueous solution in which humic acids are dissolved, or by suspending carbon black powder in an aqueous solution in which humic acids are dissolved. Can do. The humic acids used here are usually humic acids, humic acid salts, and salts of these derivatives.

  Such carbon black is a substance already known in Japanese Patent Laid-Open No. 2000-26141.

  Incidentally, the various water-soluble carbon materials as described above may be added to the water in the storage tank 6 in the form of powder, or may be added to the water in the storage tank 6 in the state of an aqueous solution or suspension. .

  On the other hand, the chemical | medical agent supplied with respect to the storage tank 6 from the 2nd chemical injection device 11 is a flocculant. The flocculant used here can form aggregates (floc) by aggregating suspended substances (SS particles) and water-soluble carbon materials suspended in the water stored in the storage tank 6. Although it will not specifically limit if it is a thing, For example, they are the coagulant | flocculant and alkaline-earth metal salt which have a positive charge.

  The aggregating agent having a positive charge is capable of changing the zeta potential of the negatively charged suspended particles contained in water to zero or a positive side, thereby forming fine flocs in the water. Examples of such a flocculant include polyaluminum chloride, sulfate band, iron chloride, polyferric sulfate, sodium aluminate and various organic organic flocculants. These flocculants may be used alone or in combination of two or more.

  Alkaline earth metal salts, on the other hand, produce low-solubility salts by attaching alkali metal ions to the hydrophilic part of surfactants such as surfactants contained in moisture, thereby producing fine flocs in moisture. Can be formed. As the alkaline earth metal salt, it is usually preferable to use a calcium salt such as calcium chloride or calcium carbonate, or a magnesium salt such as magnesium chloride or magnesium carbonate, but it is particularly preferable to use calcium chloride having high solubility in water. preferable. These alkaline earth metal salts may be used alone or in combination of two or more.

  As the flocculant, it is preferable to use a flocculant having a positive charge. Such a flocculant can effectively and quickly agglomerate the SS particles to which the organic substance is adhered and the water-soluble carbon material to which the organic substance is adsorbed in moisture, and the removal effect and removal efficiency of the organic substance. Can be increased. Incidentally, as a flocculant, a mixture of a flocculant having a positive charge and an alkaline earth metal salt may be used.

  The flocculant preferably contains a coprecipitation agent for increasing the specific gravity of the aggregate. When the coagulant containing the coprecipitation agent is used, the SS particles and the water-soluble carbon material contained in the water aggregate with the coprecipitation agent as a nucleus to form an aggregate having a large specific gravity. This agglomerate quickly settles in water. Therefore, when such a flocculant is used, the method for treating muddy water according to this embodiment can be quickly implemented, and the organic substance removal effect can be further enhanced. Examples of the coprecipitation agent that can be used here include powders of kaolin, aluminum silicate compound clay, gypsum, and diatomaceous earth. In addition, two or more kinds of these coprecipitation agents may be used in combination.

Next, a muddy water treatment method using the above-described treatment apparatus 1 will be described.
First, the muddy water to be treated is supplied to the solid-liquid separation device 3 using the supply device 2. The muddy water supplied to the solid-liquid separator 3 is separated into the solid content and moisture as described above. Then, moisture is supplied to and stored in the storage tank 6, and solid content is supplied to the filter press 5. The solid content supplied to the filter press 5 is pressurized there, and the remaining water is dehydrated. The dehydrated water is supplied to the storage tank 6 through the supply path 12 and stored together with the water from the solid-liquid separator 3.

  The water stored in the storage tank 6 contains various organic substances derived from muddy water. This organic substance may be contained in water in a state of adhering to various suspended substances (SS particles) or in a dissolved state. The SS particles are usually present in water as a suspended substance having a negative charge.

  Next, the above-mentioned water-soluble carbon material is added from the first chemical injector 10 to the water stored in the storage tank 6. The water-soluble carbon material added to the water dissolves in the water and quickly diffuses throughout the water. The water-soluble carbon material diffused in moisture effectively adsorbs organic substances contained in moisture, particularly organic substances dissolved in moisture. In order to enhance the adsorption effect of the organic substance by the water-soluble carbon material, it is necessary to increase the contact efficiency between the water-soluble carbon material and moisture. Is preferably stirred.

  Here, the organic substance adsorbed by the water-soluble carbon material usually has an octanol / water partition coefficient of 2 or more, more surely 5 or more. Here, the octanol / water partition coefficient is as follows when a predetermined amount of an organic substance to be measured (referred to as an objective organic substance for convenience) is added to and dissolved in a mixture of equal volumes of octanol and water. The logarithmic value (log value) calculated | required by Formula (2) of this. In the formula (2), C represents the amount of the target organic substance contained in the octanol phase, and D represents the amount of the target organic substance contained in the aqueous phase.

  In addition, although circumstances may differ depending on the implementation environment of the treatment method of the present invention, an organic substance having an octanol / water partition coefficient smaller than 2 may not be easily adsorbed by the water-soluble carbon material.

  Organic substances having an octanol / water partition coefficient of 2 or more usually include various harmful substances, specifically organometallic compounds such as persistent organic pollutants and organotin compounds. That is, persistent organic pollutants and organometallic compounds belong to a range of organic substances that can be removed from moisture by the treatment method of the present invention.

  Here, “residual organic pollutants” are organic substances subject to the Stockholm Convention (POPs Convention) aimed at protecting human health and protecting the environment, particularly polychlorinated dibenzo-para-dioxins ( Dioxins such as PCDDs) and polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls such as coplanar polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), aldrin, endrin, chlordane, dildrin, heptachlor, milex, toxaphene It means various organic substances (POPs: Persistent Organic Pollutants) that are not easily decomposed in the environment such as organic chlorine compounds such as hexachlorobenzene. However, in the following, the term “dioxins” refers to polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinated dibenzofurans in accordance with the provisions of Article 2 of the Act No. 105 of 1999 “Special Act on Countermeasures against Dioxins”. In addition to (PCDFs), it is used to mean including coplanar polychlorinated biphenyls (Co-PCBs).

  Incidentally, the octanol / water partition coefficient of dioxins is as shown in Table 1 according to the “Environment Prevention Technology and Regulations Dioxins” published by the Japan Association for Industrial Environment Management, and is 5 or more. In addition, according to the “Endocrine Disruption Chemical Data Collection” published by the Graduate School of Meat Hygiene, Tokyo Metropolitan Institute of Health, August 1998, the octanol / water partition coefficient of examples of persistent organic pollutants other than dioxins As shown in Table 2, it is 5 or more. Furthermore, the octanol / water partition coefficient of organometallic compounds, such as tributyltin compounds frequently used in antifouling paints for ships, is the fish of “Tributyltin (TBT)” issued by the Environmental Insurance Department of the Environment Agency General Environmental Policy Bureau in August 2001. According to the report (draft) on the test results of the endocrine disrupting effect given to the human body, it is in the range of 3.19 to 4.76.

  The addition amount of the water-soluble carbon material necessary for adsorbing the organic substance contained in the moisture, that is, the addition amount of the water-soluble carbon material with respect to the moisture stored in the storage tank 6 is the content and use of the flocculant described later. Although it varies depending on the amount, it is usually preferably set to 0.5 mg or more and more preferably set to 1 mg or more per 1 liter of water. When this addition amount is less than 0.5 mg, it may be difficult to effectively adsorb organic substances contained in moisture. In addition, although the addition amount of the water-soluble carbon material can increase the adsorption efficiency of the organic substance as the amount is set larger, in general, even if it exceeds 100 mg per 1 liter of water, the effect associated therewith cannot be obtained. It is uneconomical. Therefore, the amount of water-soluble carbon material added to 1 liter of water is preferably set to 100 mg or less.

  Next, a flocculant is added from the second chemical injection device 11 to the water to which the water-soluble carbon material is added. As a result, the SS particles to which the organic substance is adhered and the water-soluble carbon material to which the organic substance is adsorbed are aggregated by the action of the aggregating agent to be aggregated and are precipitated in the moisture. As a result, the water in which the aggregates have settled, that is, the supernatant of the water stored in the storage tank 6, is substantially free of suspended organic substances and dissolved organic substances attached to the SS particles. Purified. The supernatant liquid is discharged to the outside of the storage tank 6 through the discharge path 8.

  Therefore, according to the method for treating muddy water according to this embodiment, organic substances, particularly residual organic pollutants such as dioxins and organic substances can be obtained from muddy water without using a complicated apparatus such as an adsorption tower or an ultraviolet ray apparatus. Water from which harmful organic substances such as metal compounds are removed can be easily obtained through the discharge path 8.

  On the other hand, agglomerates generated in moisture, that is, precipitates, are taken out from the bottom of the storage tank 6 to the outside of the storage tank 6 through the discharge unit 9. The taken out precipitate is usually mixed with the solid content (dehydrated cake) dehydrated in the filter press 5. Then, the organic material is removed from the mixture by a treatment method as described later, if necessary.

[Modification of Form 1]
In the above-described embodiment 1, the flocculant is added to the water stored in the storage tank 6 after adding the water-soluble carbon material. However, the water-soluble carbon material and the flocculant are simultaneously added to the water. It can also be added. However, in order to more reliably separate organic substances in water from the water as aggregates, it is usually preferable to add a flocculant after adding a water-soluble carbon material to the water.

Form 2
With reference to FIG. 2, Embodiment 2 of the processing method of the muddy water which concerns on this invention is demonstrated. FIG. 2 is a schematic view of a treatment apparatus for carrying out the muddy water treatment method according to this embodiment. The treatment apparatus 20 includes a supply device 21, a first chemical addition device 22, a first solid-liquid separation device 23, and a filter. A press 24 is mainly provided.

  The supply device 21 is for supplying muddy water to be processed to the first solid-liquid separation device 23. The 1st chemical | medical agent addition apparatus 22 is for adding a chemical | medical agent with respect to the muddy water currently supplying with respect to the 1st solid-liquid separation apparatus 23 by the supply apparatus 21, and the 1st chemical injection device 25 and the 2nd chemical injection. Instrument 26. Each of the drug injectors 25 and 26 is moving a storage part (not shown) for storing the medicine and the medicine stored in the storage part toward the first solid-liquid separation device 23 in the supply device 21. And a pump (not shown) for supplying the muddy water. In addition, the chemical | medical agent supplied with respect to muddy water from the 1st chemical injection device 25 is the same water-soluble carbon material as what is used in the above-mentioned form 1. Moreover, the chemical | medical agent supplied with respect to muddy water from the 2nd chemical injection device 26 is the same coagulant | flocculant as what is used in the above-mentioned form 1.

  The first solid-liquid separation device 23 separates the muddy water supplied from the supply device 21 into solids (that is, solid phase) such as sand, earth and sand, sludge, and aggregates, and moisture (that is, liquid phase). A first discharge path 27 having a pump (not shown) for discharging the separated water to the outside, and set so that the separated solid content can be supplied to the filter press 24. Has been.

  The filter press 24 pressurizes the solid content from the first solid-liquid separator 23 and dehydrates the water remaining in the solid content. The dehydrated water is supplied via the supply device 21. A reflux path 28 for refluxing the solid-liquid separator 23 is provided. The reflux path 28 communicates with the upstream side of the first drug addition device 22 in the supply device 21.

Next, a method for treating muddy water using the above-described treatment apparatus 20 will be described.
First, the muddy water to be treated is supplied to the first solid-liquid separator 23 using the supply device 21. At this time, the chemical is added to the muddy water (first addition step). Specifically, the water-soluble carbon material is added from the first chemical injection device 25 to the muddy water that is moving toward the first solid-liquid separation device 23 from the supply device 21. The water-soluble carbon material added to the muddy water dissolves in the water of the muddy water and quickly diffuses throughout the water. The water-soluble carbon material diffused in moisture effectively adsorbs organic substances contained in moisture, particularly organic substances dissolved in moisture. In addition, the addition amount of the organic substance adsorbed by the water-soluble carbon material and the water-soluble carbon material is the same as in the case of the above-described embodiment 1.

  Further, in the supply device 21, the flocculant is added from the second chemical injector 26 to the muddy water to which the water-soluble carbon material is added and moving toward the first solid-liquid separation device 23. Thereby, the SS particles to which the organic substance is adhered and the water-soluble carbon material to which the organic substance is adsorbed suspended in the water of the muddy water are aggregated by the action of the aggregating agent to become an aggregate.

  The muddy water to which the water-soluble carbon material and the flocculant are added as described above is subjected to solid-liquid separation in the first solid-liquid separation device 23 (first separation step). That is, the muddy water is separated into solids (that is, the first solid phase) such as agglomerates generated by the addition of sand, earth and sand, sludge, and a flocculant, and moisture (that is, the first liquid phase). The separated water is purified to a state substantially free of suspended organic substances and dissolved organic substances attached to the SS particles as a result of the separation of aggregates and the like. This moisture is discharged outside the first solid-liquid separator 23 through the first discharge path 27.

  On the other hand, the separated solid content is supplied to the filter press 24. Then, the solid content supplied to the filter press 24 is pressurized there, and the remaining water is dehydrated. At this time, the organic substance contained in the solid content may be eluted in the moisture. However, since the water is mixed with the muddy water that is moving through the supply device 21 through the reflux path 28, the water-soluble carbon material and the flocculant are added again. Is separated as a solid content in the first solid-liquid separator 23 as an aggregate.

  As described above, according to the muddy water treatment method according to this embodiment, residual organic contamination such as organic substances, particularly dioxins, can be obtained from muddy water without using a complicated device such as an adsorption tower or an ultraviolet device. Water from which harmful organic substances such as substances and organometallic compounds are removed can be easily obtained through the first discharge path 27.

  On the other hand, the organic substance is removed from the solid content (dehydrated cake) dehydrated in the filter press 24 by a treatment method as described later, if necessary.

[Modification of Form 2]
(1) With reference to FIG. 3, the processing apparatus for enforcing the muddy water processing method which concerns on the modification of the form 2 is demonstrated. In the figure, the processing device 30 further includes a second solid-liquid separation device 31 and a second chemical addition device 32 in the processing device 20 described above. In FIG. 3, the same parts as those of the processing apparatus 20 shown in FIG.

  The second solid-liquid separation device 31 is in communication with the first discharge path 27, and the moisture (first liquid phase) supplied from the first discharge path 27 is converted into solids such as aggregates (that is, the second solid phase). And for further separation into water (ie, the second liquid phase). The second solid-liquid separator 31 supplies a second discharge path 33 having a pump (not shown) for discharging the separated moisture to the outside, and the separated solid content to the filter press 24. Supply path 34.

  The second drug addition device 32 is for supplying the drug to the moving water from the first solid-liquid separation device 23 toward the second solid-liquid separation device 31 through the first discharge path 27. It has a three drug injector 35 and a fourth drug injector 36. Each of the drug injectors 35 and 36 is configured in the same manner as the drug injectors 25 and 26 described above. In addition, the chemical | medical agent supplied with respect to a water | moisture content from the 3rd chemical injection device 35 is the same water-soluble carbon material as what is used in the above-mentioned form 1. Moreover, the chemical | medical agent supplied with respect to a water | moisture content from the 4th chemical injection device 36 is the same coagulant | flocculant as what is used in the above-mentioned form 1.

Next, a muddy water treatment method using the above-described treatment apparatus 30 will be described.
The muddy water to be treated is treated in the same manner as in the case of the treatment device 20 described above, and in the first solid-liquid separation device 23, solid content such as agglomerates generated by the addition of sand, earth and sand, sludge, and a flocculant. (Ie, the first solid phase) and water (ie, the first liquid phase). The separated solid content is processed in the filter press 24 as in the case of the processing apparatus 20.

  On the other hand, the water separated in the first solid-liquid separator 23 is further supplied to the second solid-liquid separator 31 through the first discharge path 27. At this time, the drug is added to the moisture (second addition step). Specifically, the water-soluble carbon material is added from the second chemical injection device 35 to the water moving toward the second solid-liquid separation device 31 through the first discharge path 27. The water-soluble carbon material added to the moisture dissolves and diffuses in the moisture, and adsorbs the above-described organic substances remaining in the moisture, in particular, the organic substances dissolved in the moisture. In addition, the addition amount of the water-soluble carbon material added with respect to moisture here may be set similarly to the addition amount of the water-soluble carbon material with respect to the muddy water from the first chemical injection device 25, or compared with the addition amount. May be set to a small amount.

  Further, in the first discharge path 27, the flocculant is added from the fourth chemical injector 36 to the water that is added with the water-soluble carbon material and is moving toward the second solid-liquid separator 31. Thereby, the SS particles to which the organic substance is adhered and the water-soluble carbon material to which the organic substance is adsorbed suspended in moisture are aggregated into an aggregate by the action of the aggregating agent.

  The water to which the water-soluble carbon material and the flocculant are added as described above is further solid-liquid separated in the second solid-liquid separation device 31 (second separation step). That is, the moisture is separated into a solid (ie, the second solid phase) mainly composed of the above-mentioned aggregates and moisture (ie, the second liquid phase). The separated water is purified to a state in which suspended organic substances and dissolved organic substances attached to the SS particles are more reliably removed as a result of separation of aggregates and the like. . This moisture is discharged to the outside of the second solid-liquid separator 31 through the second discharge path 33.

  On the other hand, the solid content separated in the second solid-liquid separation device 31 is supplied to the filter press 24 and mixed with the solid content separated in the first solid-liquid separation device 24. Then, the solid content supplied to the filter press 24 is pressurized there, and the remaining water is dehydrated. The dehydrated water is mixed with the muddy water moving through the supply device 21 through the reflux path 28 and processed as described above.

  As described above, according to the muddy water treatment method according to this modified example using the treatment device 30, compared to the case of the treatment method using the treatment device 20, the residue of organic substances, in particular, dioxins, etc. from the muddy water. Moisture from which harmful organic substances such as volatile organic pollutants and organometallic compounds are more reliably removed can be easily obtained through the second discharge path 33.

  On the other hand, the organic substance is removed from the solid content (dehydrated cake) dehydrated in the filter press 24 by a treatment method as described later, if necessary.

(2) In the muddy water treatment method using the treatment apparatus 20 and the treatment apparatus 30 described above, the flocculant is added after the addition of the water-soluble carbon material in the first addition step. The agent can be added to the muddy water at the same time. However, in order to more reliably separate the organic substance in the water of the muddy water from the water as an aggregate, it is usually preferable to add the flocculant after adding the water-soluble carbon material to the muddy water. The same applies to the second addition step in the processing method using the processing apparatus 30.

(3) In the muddy water treatment method using the above-described treatment device 20 and treatment device 30, the first addition step is directly performed on the muddy water that is moving toward the first solid-liquid separation device 23 with the supply device 21. However, the muddy water supplied to the first solid-liquid separator 23 is temporarily stored in the storage tank, and after the first addition step is performed in this state, the muddy water is supplied to the first solid-liquid separator 23. You can also. The same applies to the second addition step with respect to the water that is moving while moving the first discharge path 27 toward the second solid-liquid separator 31.

Solid content processing method Since the solid content (solid phase) obtained in each of the above-mentioned forms contains the organic material as described above, if it is discarded or reused as it is, it may cause environmental pollution. For this reason, this solid content usually needs to be subjected to an organic substance removal treatment.

  The removal process of the organic substance contained in the solid content can be performed based on various known methods. However, this removal treatment is performed according to the method described in Japanese Patent Application No. 2003-353576 filed before the present application by the present applicant, specifically, an iron oxide such as iron trioxide (magnetite) with respect to the solid matter, A mixture is prepared by adding at least one of an alkali metal compound and an alkaline earth metal compound (for example, calcium oxide), and the mixture is heat-treated (preferably heat-treated at 300 ° C. or higher). Is particularly preferred.

Example 1
An acetone solution of dioxin standards containing 7 polychlorinated dibenzo-para-dioxins (PCDDs), 10 polychlorinated dibenzofurans (PCDFs) and 14 coplanar polychlorinated biphenyls (Co-PCBs) was prepared. Then, 2 ml of this acetone solution was added to 1 liter of tap water stored in a beaker and dissolved to obtain test water.

  On the other hand, a water-soluble carbon material was produced according to the method described in Example 1 of Japanese Patent No. 3079260, and the dispersion rate in water was determined. Here, an aqueous solution containing 20% by weight of a water-soluble carbon material was prepared, and 2 g thereof was placed in a 2 ml microtube. Then, the microtube was centrifuged at 10,000 G for 15 minutes, and the supernatant was removed to collect the sediment. The collected sediment was dried at 105 ° C. for 2 hours and then weighed, and the dispersion rate was determined based on the above-described formula (1). As a result, it was 95%. In this process, the product name “Universal Cooling Centrifuge 5922” of Kubota Shoji Co., Ltd. is used as the centrifuge, and the product name “Microrotor AT-2018M” of the company is used as a rotor for mounting the microtube. Was used.

  Next, the obtained water-soluble carbon material was dissolved in distilled water to prepare a water-soluble carbon material aqueous solution, and the water-soluble carbon material aqueous solution was added to the test water. The amount of water-soluble carbon material aqueous solution added was set to 100 mg in terms of water-soluble carbon material.

  Next, 2.5 g of calcium chloride powder as a flocculant was added to the test water to which the water-soluble carbon material aqueous solution was added and stirred. As a result, aggregates were formed in the test water and settled.

  The test water in which the aggregates were formed was suction filtered using a glass fiber filter paper (Advantech Co., Ltd., trade name “GC-50”) having a retained particle diameter of 0.5 μm. And the residue containing the aggregate collected by the glass fiber filter paper was air-dried for 12 hours together with the glass fiber filter paper, and then the dioxins contained therein were subjected to Soxhlet extraction using toluene for 16 hours. Moreover, liquid-liquid extraction using dichloromethane was repeated 3 times for the filtrate, and dioxins contained in the filtrate were extracted. Furthermore, the inner wall surface of the beaker was washed with dichloromethane, and dioxins adhering to the inner wall surface were collected.

  For each of the Soxhlet extract, liquid-liquid extract and washing solution, add the internal standard for cleanup spike and then purify using a multilayer silica gel column. Add the internal standard for syringe spike to the resulting purified solution. 30 μl of analytical sample was obtained. In addition, in order to confirm the concentration of dioxins contained in the test water, 2 ml of the acetone solution of the above-mentioned dioxin standard substance is dispensed into a small concentration tube, and then the internal standard substance for cleanup spike and the internal standard substance for syringe spike A sample for confirming the concentration was obtained by the same process using. The internal standard substances for cleanup spike and syringe spike were those specified in JIS K 0312: 1999 “Measurement method of dioxins and coplanar PCB in industrial water and industrial wastewater”.

  3 μl of each analysis sample and concentration confirmation sample was analyzed using a high-resolution gas chromatograph mass spectrometer (HRGC / HRMS). And based on the analysis result, the recovery rate of each PCDDs, each PCDFs, and each Co-PCBs contained in the test water was calculated individually. The results are shown in Table 3. The recovery rate is a value obtained by the following equation (3). In the formula, X represents the amount of the specific dioxins contained in the test water, and Y represents the amount of the specific dioxins contained in the Soxhlet extract, liquid-liquid extract or washing solution. The total recovery rate is the total recovery rate obtained for each of the Soxhlet extract, the liquid-liquid extract, and the cleaning solution. In Table 3, Co-PCBs are displayed according to the IUPAC classification. This also applies to Tables 4 and 5.

  According to Table 3, it can be seen that each dioxin is hardly contained in the liquid-liquid extract and the cleaning liquid. This indicates that dioxins contained in the test water are effectively removed from the test water by the above-described treatment.

Example 2
The amount of water-soluble carbon material aqueous solution added to the test water was changed to 1 mg in terms of water-soluble carbon material, and a mixture of 2.5 g of calcium chloride, 0.2 g of kaolin and 0.025 g of polyaluminum chloride was used as the flocculant. Except for this point, the same processing as in Example 1 and the operation of collecting an analytical sample were performed to determine the recovery rate. The results are shown in Table 4. According to Table 4, it can be seen that each dioxin is hardly contained in the liquid-liquid extract and the cleaning liquid. This indicates that the dioxins contained in the test water are effectively removed from the test water even in the case of the above-described treatment in which the amount of water-soluble carbon material added is significantly reduced compared to Example 1. ing.

  In addition, when Table 3 and Table 4 are compared, it is thought that it was difficult to extract dioxins from the aggregate obtained in Example 1 that the recovery rate total is very small in Table 3. . That is, in Example 1, it is considered that dioxins contained in the aggregates were difficult to extract in the above-described Soxhlet extraction method.

Example 3
Except that 1 mg of carbon black (trade name “HA3” from Tokai Carbon Co., Ltd.) adsorbing humic acids as a water-soluble carbon material was used, the same processing as in Example 2 and the sampling operation for analysis were performed. The recovery rate was determined. The results are shown in Table 5. According to Table 5, it can be seen that each dioxin is hardly contained in the liquid-liquid extract and the cleaning liquid. This indicates that dioxins contained in the test water are effectively removed from the test water. In addition, when the dispersion rate in water of the water-soluble carbon material used in this Example was determined by the same method as that described in Example 1, it was 42%.

Examples 4 to 8 and Comparative Example 1
An organic compound standard substance shown in Table 6 was added to 10 ml of water, and two test waters having a concentration of the organic compound standard substance of 1 μg / L (1 ppb) were prepared. Then, the water-soluble carbon material used in Example 1 was added to one test water, and the water-soluble carbon material used in Example 3 was added to the other test water. The addition amount of the water-soluble carbon material was set to 0.1 mg for any test water. Therefore, the concentration of the water-soluble carbon material in each test water is 10 mg / L.

  Next, a flocculant was added to each test water to which the water-soluble carbon material was added, and the resulting aggregate was precipitated. The flocculant used here is a mixture of calcium chloride 0.025 g, kaolin 0.002 g and polyaluminum chloride 0.00025 g. The supernatant of the test water in which the aggregate was precipitated was collected, and the concentration of the organic compound standard substance contained therein was measured with a gas chromatograph mass spectrometer (GC / MS). And the removal rate of the organic compound standard substance from test water was calculated | required from the measurement result. Here, the removal rate is obtained based on the following equation (4). In the formula (4), M represents the amount of the organic compound standard substance contained in the test water, and N represents the amount of the organic compound standard substance contained in the supernatant. The results are shown in Table 6. The octanol / water partition coefficients shown in Table 6 were quoted from “Water Supply Test Methods, 2001 Edition” published by Japan Water Works Association.

  According to Table 6, the removal rate of organic compound standard substances having an octanol / water partition coefficient of 2 or more is 50% or more (Examples 4 to 8). In particular, the removal rate of the organic compound standard substance having the same partition coefficient of 5 or more is 100% (Example 8). From this result, it can be seen that according to the method for treating muddy water according to the present invention, a liquid phase in which an organic substance having an octanol / water partition coefficient of 2 or more, particularly 5 or more is removed can be easily obtained from muddy water.

Schematic of the processing apparatus used in order to implement the form 1 of the muddy water processing method which concerns on this invention. Schematic of the processing apparatus used in order to implement the form 2 of the muddy water processing method which concerns on this invention. The schematic diagram of the processing apparatus used in order to implement the modification of form 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Solid-liquid separation apparatus 7 Chemical injection apparatus 22 1st chemical | medical agent addition apparatus 23 1st solid-liquid separation apparatus 31 2nd solid-liquid separation apparatus 32 2nd chemical | medical agent addition apparatus

Claims (5)

A separation process for separating muddy water into a liquid phase and a solid phase;
An addition step of adding a water-soluble carbon material and a flocculant to the liquid phase;
Removing the aggregate from the liquid phase ,
As the water-soluble carbon material, a carbon material that is surface-modified by introduction of a carboxyl group or a hydroxyl group or a carbon material that contains an inorganic material having a carboxyl group or a hydroxyl group is used.
Muddy water treatment method.   The method for treating muddy water according to claim 1, further comprising a step of mixing the solid phase and the aggregate. A first addition step of adding a water-soluble carbon material and a flocculant to the muddy water;
A first separation step of separating the muddy water after the first addition step into a first liquid phase and a first solid phase ;
As the water-soluble carbon material, a carbon material that is surface-modified by introduction of a carboxyl group or a hydroxyl group or a carbon material that contains an inorganic material having a carboxyl group or a hydroxyl group is used.
Muddy water treatment method. A first addition step of adding a water-soluble carbon material and a flocculant to the muddy water;
A first separation step of separating the muddy water after the first addition step into a first liquid phase and a first solid phase;
A second addition step of further adding a water-soluble carbon material and a flocculant to the first liquid phase;
A second separation step of further separating the first liquid phase after the second addition step into a second liquid phase and a second solid phase ;
As the water-soluble carbon material, a carbon material that is surface-modified by introduction of a carboxyl group or a hydroxyl group or a carbon material that contains an inorganic material having a carboxyl group or a hydroxyl group is used.
Muddy water treatment method.   The method for treating muddy water according to claim 4, further comprising a step of mixing the first solid phase and the second solid phase.

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