JP5343051B2 - Sewage purification method, flocculant, sewage purification device and oil extraction system using the same - Google Patents

Abstract

A water purification method capable of removing an organic acid from large quantities of sewage at a high speed, a coagulant, a water purifying apparatus, and an oil extracting system using the apparatus are provided. Herein, the water purification method capable of removing the organic acid contained in the large quantity of sewage at the high speed, comprising the steps of: mixing separately a water-soluble polymer having acidic groups 6 and a trivalent metal salt 7 thereby to form agglomerates containing the organic acid 5; and removing the agglomerates 8 thereby to remove the organic acid 5 contained in the sewage. Accordingly, this water purification method allows the coagulant, the water purifying apparatus and the oil extracting system using the apparatus to be realized and provided.

Description

  The present invention relates to a sewage purification method, a flocculant, a sewage purification apparatus, and an oil extraction system using the same.

  Sewage (contaminated water) generated during oil field mining or oil extraction from oil sand contains a large amount of organic acids (for example, acetic acid, valeric acid, naphthenic acid, etc.) coexisting with crude oil. Therefore, when the sewage from the oil field is discharged into the sea, rivers, etc., the organic acid has a great influence on the ecosystem, so it is necessary to discharge it after removing the organic acid contained in the sewage. Therefore, in view of the enormous amount of sewage generated, there is a need for a sewage treatment technique that removes the organic acid at high speed and in large quantities.

FIG. 10 is a diagram showing a known method for removing contaminating fine particles contained in sewage. In the technique shown in FIG. 10, first, polyaluminum chloride (PAC) or iron sulfate (in which PAC is mixed in FIG. 10) is mixed, and small aggregates (specifically, about several tens to several hundreds). μm) is formed. The micro floc 1 is formed by aggregation of the contaminated fine particles 2 contained in the sewage and the magnetic powder 4 previously mixed with the sewage with aluminum ions (Al ³⁺ ) as the center.

  After the formation of the micro floc 1, by mixing a polymer such as polyacrylamide in the same system, the floc having a larger particle size (specifically several hundred to several thousand μm) than the micro floc 1 in water. 3 can be formed. The sewage containing the floc 3 having a large particle size can be removed from the sewage by separating the floc 3 by, for example, filtering or adsorbing the sewage using magnetism. In addition, in the example shown in FIG. 10, since the floc 3 contains the magnetic powder 4, it can be easily removed by using magnetism.

  In addition, for example, a method of removing using an ion exchange resin, a reverse osmosis membrane or the like is known, and for example, Patent Document 1 discloses that an organic acid is removed using a contact material containing fibrous activated carbon. Is described. Further, for example, Patent Document 2 describes that an oil is agglomerated by mixing a polymer having a specific ammonium salt structure and an anionic polymer into wastewater containing the oil to remove the oil. Yes.

JP 2003-144839 A JP 2004-255349 A

  However, in the method shown in FIG. 10, according to the study by the present inventors, although organic particulates such as acetic acid, valeric acid, and naphthenic acid in sewage cannot be removed, the contaminating fine particles can be removed. In particular, the organic acid usually has an ammonium salt structure, an alkali metal salt, or the like, and thus is more difficult to remove from wastewater.

Moreover, in the method using activated carbon, ion exchange resin, reverse osmosis membrane, etc., although organic acid can be removed to some extent, its treatment capacity is limited, and activated carbon, ion exchange resin, reverse osmosis membrane to be used Etc. may need to be exchanged frequently.
For example, when an organic acid is adsorbed on activated carbon, ion exchange resin or the like, the amount of adsorption increases as the surface area of activated carbon or ion exchange resin increases. Therefore, a large surface area can be ensured per unit volume by reducing their size (particle size). However, the smaller the particle size is, the more difficult it is to carry activated carbon or ion exchange resin, which makes it difficult to handle. Moreover, since activated carbon also adsorbs organic substances other than organic acids, there is a problem that the amount of organic acid adsorbed decreases when the oil component is adsorbed before the organic acid.

  Furthermore, in the case of a reverse osmosis membrane, for example, if the pores existing on the membrane surface are clogged with contaminants, the membrane cannot be used any more, and there is a problem that it is difficult to treat a large amount of sewage at high speed.

  Moreover, for example, in the technique described in Patent Document 2, only the oil is removed, and the problem of removing the organic acid in the sewage still has not been solved.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a sewage purification method, a flocculant, a sewage purification apparatus, and a sewage purification apparatus that can remove organic acids from a large amount of sewage at high speed. It is to provide an oil extraction system.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a sewage purification method and a flocculant capable of removing organic acids from a large amount of sewage at high speed by using a specific polymer compound and a specific salt. As a result, the present inventors have found that a sewage purification apparatus and an oil extraction system using the same can be provided, and the present invention has been completed.

  ADVANTAGE OF THE INVENTION According to this invention, the sewage purification method which can remove an organic acid from a large amount of sewage, a flocculant, a sewage purification apparatus, and an oil extraction system using the same can be provided.

It is a figure which shows the aggregate formation mechanism in this invention. It is a figure which shows typically 1st embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically 2nd embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically 3rd embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically 4th embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically 5th embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically 6th embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically 7th embodiment about the sewage purification apparatus of this invention. It is a figure which shows typically the oil-component extraction system using the sewage purification apparatus of this invention. It is a figure which shows the mechanism in which the conventional dirty fine particles are aggregated.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment” as appropriate) will be described in detail, but the present embodiment is not limited to the following contents and does not depart from the gist thereof. Any change can be made within the range.

[1. Sewage purification method]
The sewage purification method according to the present embodiment is a sewage purification method that removes organic acids contained in sewage, and includes a water-soluble polymer compound having an acidic group and a trivalent metal salt. Separately mixed to produce an agglomerate containing an organic acid, and the agglomerate is removed to remove the organic acid contained in the sewage.

First, the aggregate formation mechanism in the sewage purification method according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an aggregate formation mechanism in the present invention.
For convenience of explanation, in the mechanism shown in FIG. 1, a carboxyl group is exemplified as the acidic group that the organic acid 5 has, and the carboxyl group is also exemplified as the acidic group that the water-soluble polymer compound 6 having an acidic group has, The trivalent metal salt 7 is exemplified by iron (III) chloride that is ionized in waste water to generate iron (III) ions (Fe ³⁺ ).

  First, a water-soluble polymer compound having an acidic group (hereinafter referred to as “acidic polymer compound”) 6 is mixed with sewage containing the organic acid 5 shown in the upper part of FIG. Then, the organic acid 5 and the acidic polymer compound 6 coexist in the sewage (the state shown in the center part of FIG. 1).

And when trivalent metal salt 7 is further mixed with such sewage, two carboxylate ions (—COO ⁻ ) generated from carboxyl groups (—COOH) contained in acidic polymer compound 6; One carboxylate ion produced from the carboxyl group contained in the organic acid 5 and a trivalent iron ion are ion-bonded (state shown in the lower part of FIG. 1). At this time, the acidic polymer compound 6 was in a state of being dissolved in water, but due to the ionic bond, one molecule having a very large molecular weight including iron ion (III) (specifically, the molecular weight is several Molecules having a molecular weight of 1,000 to several tens of thousands) and cannot be completely dissolved in the sewage, and precipitate together with the organic acid 5 as aggregates 8. And the organic acid 5 contained in the sewage can be removed from the sewage by removing the precipitated aggregate 8 from the sewage.
With the above mechanism, the organic acid in the sewage can be removed by the sewage purification method according to the present embodiment.

  For example, even when only a trivalent metal salt is mixed with sewage without using an acidic polymer compound, a trivalent metal ion to be generated and an anion generated from an organic acid present in the sewage Are ionically bonded to form a salt. However, since the molecular weight of the organic acid is usually about several hundreds, the average molecular weight of the generated salt is also several hundred to several thousand, and the solubility is not low enough to precipitate in sewage. That is, a certain amount of the generated salt is dissolved in the sewage, and the removal efficiency of the organic acid in the sewage decreases.

  However, according to the sewage purification method according to the present embodiment, the trivalent metal ion generated in the sewage is ion-bonded not only to the anion generated from the organic acid but also to the anion generated from the acidic polymer compound. The molecular weight of the formed salt is about tens of thousands. Therefore, the solubility of the salt in water is significantly reduced, and the salt is precipitated in the waste water as an aggregate together with the organic acid. The amount of the acidic polymer compound that is ionically bonded to the trivalent metal ion is not particularly limited, but as shown in FIG. 1, 2 mol of the acidic polymer compound and 1 mol of the trivalent metal ion are When a salt is formed by ionic bonding, the overall molecular weight becomes larger, the solubility in water further decreases, and the organic acid removal efficiency is further improved.

  Hereinafter, the organic acid contained in the sewage, the acidic polymer compound used to remove the organic acid, and the trivalent metal salt in the sewage purification method according to the present embodiment will be described.

[1-1. Organic acid]
As long as the organic acid removed in the sewage purification method according to the present embodiment is a compound containing one or more carbon atoms and having an acidic group, other structures are arbitrary. The carbon number of the organic acid is arbitrary as long as the effects of the present invention are not significantly impaired, but it is 1 or more, usually 12 or less, preferably 10 or less, more preferably 8 or less, particularly preferably 6 or less. is there. In addition, since the organic acid with many carbon numbers contained is hard to melt | dissolve in water, it becomes difficult to be contained in sewage.

Moreover, the kind of acidic group which an organic acid has is arbitrary as long as the effect of the present invention is not significantly impaired. Examples of such acidic groups include a carboxyl group and a sulfonic acid group (—SO ₃ H). In addition, these acidic groups may be in the form of anions due to elimination of protons (H ⁺ ).

Specific examples of organic acids contained in sewage can be removed as long as the effects of the present invention are not significantly impaired as described above. For example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid , Naphthenic acid, benzenesulfonic acid, a compound in which a carboxyl group or a sulfonic acid group is bonded to cyclopentane, a compound in which a carboxyl group or a sulfonic acid group is bonded to cyclohexane, and the like. Among them, since the sewage to which the sewage purification method according to the present embodiment is suitably applied is sewage generated from oil sand, the organic acids include acetic acid, valeric acid, naphthenic acid, and cyclohexane that can be contained in the sewage. A compound having a carboxyl group bonded to pentane and a compound having a carboxyl group bonded to cyclohexane are preferred.
In addition, the organic acid contained in sewage may be single 1 type, and 2 or more types may be contained by arbitrary ratios and combinations.

  The amount of the organic acid contained in the sewage is arbitrary as long as the effects of the present invention are not significantly impaired. Therefore, for example, when the amount of the organic acid contained in the sewage is a huge amount, the sewage purification method according to this embodiment is repeatedly applied to the same sewage, and the organic acid contained in the sewage is gradually removed. What should I do?

[1-2. Polymer compound having acidic group (acidic polymer compound)]
The acidic polymer compound used in the sewage purification method according to this embodiment is arbitrary as long as the effects of the present invention are not significantly impaired. The acidic polymer compound has an acidic group, dissolves in water, and further has a high molecular weight.

  The type of acidic group possessed by the acidic polymer compound is [1-1. As in the case of the organic acid], it is optional as long as the effects of the present invention are not significantly impaired, and examples thereof include a carboxyl group and a sulfonic acid group. Among them, a carboxyl group is preferable. In addition, as for the acidic group contained in one molecule | numerator acidic polymer compound, 1 type may be contained independently and 2 or more types may be contained by arbitrary ratios and combinations.

  The “compound soluble in water” refers to “a compound not insoluble in water”. That is, the compound does not cause precipitation of the compound when dispersed in water. However, for example, sucrose (sucrose) is generally recognized as a “compound that dissolves in water”, but sucrose precipitates in the solution above the saturation concentration of sucrose. Therefore, “a compound that dissolves in water” represents a compound that is generally recognized as a “compound that dissolves in water”, although precipitation occurs above the saturation concentration, but precipitation does not occur below the saturation concentration. Shall be interpreted in the broadest sense.

The acidic polymer compound has a high molecular weight. The specific molecular weight is arbitrary as long as the effects of the present invention are not significantly impaired, but the number average molecular weight of the acidic polymer compound is usually 2000 or more, preferably 5000 or more, particularly preferably 10,000 or more, and the upper limit is Usually, it is 1,000,000 or less, preferably 500,000 or less.
If the molecular weight is too small, the number of cross-linked sites of the aggregate may be too small, and the stability of the aggregate in the sewage may deteriorate, or the viscosity may become excessively large. That is, when the aggregate has such a form, it may be difficult to remove the aggregate from the wastewater. Also, if the molecular weight is too large, agglomerates are formed before the acidic polymer compound traps most of the organic acid contained in the sewage, and the organic acid in the sewage that should be removed may remain. is there.
In addition, the number average molecular weight of an acidic polymer compound can be measured using GPC (Gel permeation Chromatography; gel permeation chromatography).

  Moreover, you may change the number average molecular weight of an acidic polymer compound according to the temperature of the sewage to which the sewage purification method which concerns on this embodiment is applied. For example, when the temperature of sewage is about 40 ° C., when the number average molecular weight is about 2,000, the aggregates may be sticky and difficult to remove from the sewage. Therefore, in such a case, for example, the number average molecular weight may be set to about 5000 or more and solidified. For example, when the temperature of sewage is about 60 ° C., the number average molecular weight may be about 10,000 or more for the same reason as described above.

  Specific types of such acidic polymer compounds are not particularly limited as long as the effects of the present invention are not significantly impaired. For example, specific examples of acidic polymer compounds having a carboxyl group include polyacrylic acid and polymethacrylic acid. , Polyaspartic acid, polyglutamic acid, alginic acid, polyvinyl sulfonic acid, polystyrene sulfonic acid and the like are preferably mentioned, and these may be used alone or in combination of two or more in any ratio and combination. . Among them, polyacrylic acid is particularly preferable as the acidic polymer compound from the viewpoint that it can be obtained at a low cost and can easily be ion-bonded with a trivalent metal ion.

  In addition, alginic acid, polyaspartic acid and polyglutamic acid are preferred from the viewpoint of being an amino acid-derived raw material and particularly low environmental burden, and among them, it is derived from seaweed such as kelp, and biological raw materials can be used. From the viewpoint, alginic acid is preferred.

  In addition, for example, specific examples of the acidic polymer compound having a sulfonic acid group include polyvinyl sulfonic acid, polystyrene sulfonic acid, and the like. These may be used alone, or two or more may be arbitrarily selected. You may use it in a ratio and combination.

  For example, when comparing an acidic polymer compound having a carboxyl group with an acidic polymer compound having a sulfonic acid group, each acidic polymer compound has various advantages. An acidic polymer compound having a group and / or an acidic polymer compound having a sulfonic acid group may be used.

Specifically, for example, acidic polymer compounds having a carboxyl group are already used in familiar fields such as diapers and sanitary products, and therefore can be easily and inexpensively obtained.
On the other hand, for example, an acidic polymer compound having a sulfonic acid group can obtain a particularly stable aggregate because the sulfonic acid group has a higher acidity than the carboxyl group and is easily ionically bonded to a trivalent metal ion. .

  Moreover, it is preferable that the acidic group contained in the acidic polymer compound forms a salt with ammonia or an alkali metal from the viewpoint that the amount of the acidic polymer compound dissolved in the sewage can be further increased.

  In particular, when it is desired to use an acidic polymer compound with low water solubility, the contained acidic groups such as carboxyl group and sulfonic acid group are each made water soluble in the form of salts such as ammonium salt, sodium salt and potassium salt, respectively. The acidic polymer compound may be used in the sewage purification method according to this embodiment. In addition, by forming the acidic group contained in the acidic polymer compound in the form of a salt with a base, the generated anion can be more efficiently ion-bonded with a trivalent metal ion, resulting in more efficient organic Acid can be removed from wastewater.

[1-3. Trivalent metal salt]
The trivalent metal salt used in the sewage purification method according to the present embodiment is arbitrary as long as the effects of the present invention are not significantly impaired. However, the trivalent metal salt usually contains a trivalent metal and an anion whose valence of the metal ion.

(Trivalent metal ion)
The trivalent metal is arbitrary as long as the effects of the present invention are not significantly impaired. Moreover, even if it becomes a plurality of valences when it becomes an ion, it can be treated as a trivalent metal if the valence can be trivalent. Specific examples of such trivalent metals include metals such as iron, aluminum, neodymium, and dysprosium. Among these, iron and aluminum are preferable from the viewpoint of being abundant on the earth, being inexpensive and easily available, and iron is more preferable from the viewpoint of being cheaper. For example, in the case of iron, iron ions have two kinds of valences, divalent and trivalent. Therefore, trivalent iron ions can be obtained, for example, by mixing an oxidizing agent in a solution in which divalent and trivalent iron ions coexist, and oxidizing the contained divalent iron ions to trivalent iron ions. it can.

(anion)
The trivalent metal salt can usually be generated by dissolving the above trivalent metal in an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid, or an organic acid such as acetic acid or propionic acid. That is, a trivalent metal salt is produced by the reaction of the trivalent metal with the acid. Such an acid is optional as long as the effects of the present invention are not significantly impaired, but an inorganic acid is preferably used from the viewpoint of preventing COD (chemical oxygen demand) of sewage from becoming excessively high. . Therefore, the anion constituting the trivalent metal salt used in the sewage purification method according to this embodiment is preferably an anion generated from an inorganic acid.

(Suitable trivalent metal salt)
As described above, the trivalent metal contained in the “trivalent metal salt” is preferably iron (III), and the anion is preferably an anion derived from an inorganic acid. That is, the trivalent metal salt used in the sewage purification method according to this embodiment is preferably a salt of iron (III) and an inorganic acid.

However, the trivalent metal salt is not limited to a salt of iron (III) and an inorganic acid, and for example, polyaluminum chloride can be used. Polyaluminum chloride can be produced by mixing aluminum hydroxide and hydrochloric acid, and its structure is [Al ₂ (OH) _n Cl _6-n ] _m (where n is a number satisfying 1 ≦ n ≦ 5, m is a number satisfying m ≦ 10.) Moreover, aluminum sulfate etc. are mentioned suitably as a trivalent metal salt.

  In addition, as described above, examples of trivalent metals include neodymium and dysprosium. When these metals (specifically, rare earth metals) are used as trivalent metals, trivalent metal salts are used. From the viewpoint of high solubility in water, the form of hydrochloride, sulfate or nitrate is preferred.

[1-4. Mixing order]
As described above, in the sewage purification method according to the present embodiment, the acidic polymer compound and the trivalent metal salt are separately mixed with the sewage. As long as the acidic polymer compound and the trivalent metal salt are separately mixed, the mixing order, method, etc. are not particularly limited. However, it is preferable to first mix the acidic polymer compound with the sewage and then mix the trivalent metal salt. By using such a mixing order, the organic acid in the sewage can be removed with higher efficiency. The reason is that if a trivalent metal salt is first mixed with sewage and then an acidic polymer compound is mixed, an acidic polymer compound that does not bind to trivalent metal ions may be generated in the sewage. There is a possibility that the TOC (total organic carbon) concentration in the sewage is excessively increased by the presence of the acidic polymer compound that does not bind to the trivalent metal ion in the sewage. However, the trivalent metal salt is mixed first, and then the acidic polymer compound is mixed by mixing the amount of the acidic polymer compound whose concentration is adjusted so that the TOC concentration in the sewage does not increase excessively. You can also do it. Furthermore, the acidic polymer compound and the trivalent metal salt are mixed separately with respect to the sewage, and they are prevented from ionic bonding before ionic bonding with the organic acid (that is, aggregation without containing the organic acid). So long as they are not produced). That is, for example, using a circulating mixing tank, the acidic polymer compound is added upstream, and at the same time, the trivalent metal salt is added downstream sufficiently away from the location where the acidic polymer compound is added. May be. In this case, it is preferable to sufficiently stir the inside of the mixing tank in order to prevent the formation of an agglomerate not containing an organic acid.

  Further, the form of the acidic polymer compound and the trivalent metal salt to be mixed is arbitrary as long as the effect of the present invention is not significantly impaired, but from the viewpoint that the time required for diffusing throughout the sewage is short, the desired concentration It is preferable to mix with sewage in the form of an aqueous solution adjusted to the above. For example, when the acidic polymer compound is mixed first and then the trivalent metal salt is mixed, the trivalent metal is not sufficiently mixed (stirred) in the sewage water. When salt is mixed with sewage, agglomeration occurs partially, and the removal efficiency of organic acids in the sewage may decrease. Therefore, it is possible to easily disperse the acidic polymer compound uniformly in the sewage by dissolving the acidic polymer compound in water in the form of an aqueous solution and mixing the aqueous solution with the sewage. Therefore, the above possibilities are very slight. However, as in the case of the mixing order, even if the acidic polymer compound is not in the form of an aqueous solution, the trivalent metal salt is mixed after the acidic polymer compound is sufficiently mixed and uniformly diffused after mixing with the sewage. By mixing these, the possibility of the occurrence of partial aggregates as described above can be suppressed.

  Furthermore, in the case of a trivalent metal salt, similarly, the trivalent metal salt is mixed with sewage in the form of an aqueous solution of a trivalent metal salt in which water is dissolved in water, thereby more reliably generating a biased aggregate. Can be prevented.

[1-5. Mixing amount]
In the sewage purification method according to this embodiment, the mixing amount of the acidic polymer compound and the trivalent metal salt is arbitrary as long as the effect of the present invention is not significantly impaired, and is appropriately determined according to the amount of organic acid contained in the sewage. You only have to set it. That is, the trivalent metal ions are ion-bonded to the acidic group contained in the organic acid and the acidic group contained in the acidic polymer compound. Therefore, it is preferable that the trivalent metal ions are mixed so as to satisfy the relationship between the amounts of these substances. .

Specifically, the number of moles of metal ions (substance amount) contained in the trivalent metal salt in the wastewater is M, the number of moles of acidic groups contained in the acidic polymer compound is PA, and the number of moles of organic acid is When MA is used, it is preferable to mix the trivalent metal salt and the acidic polymer compound in the sewage so as to satisfy the following formula (1).
3 × M ≧ MA + PA (1)

  That is, the above formula (1) represents that 1 mol or more of trivalent metal ions are required for ionic bonding between 3 mol of anions and trivalent metal ions. That is, in order to form aggregates more reliably, it is preferable to mix an excessive amount of a trivalent metal salt. However, when an excessive amount of trivalent metal salt is simply mixed, the purification cost of sewage may increase. Therefore, it is preferable to mix a slightly larger amount of the trivalent metal salt than the theoretical amount with the sewage.

[1-6. Other additives]
As described above, in the sewage purification method according to the present embodiment, the acidic polymer compound and the trivalent metal salt are mixed in the sewage, but other than that, the effects of the present invention are not significantly impaired. Any additive can be mixed into the sewage.

  Examples of such additives include inorganic salts. Although there is no restriction | limiting in particular in the specific kind of inorganic salt, For example, hydrochloride of alkali metals or alkaline-earth metals, such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride; Sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And alkali metal or alkaline earth metal sulfates such as sodium nitrate, potassium nitrate, magnesium nitrate, and calcium nitrate.

  Among these, sodium chloride is preferable from the viewpoint of being readily available because it is abundant in nature. In particular, when the sewage purification method according to this embodiment is applied to sewage discharged from a seabed oil field (including seawater), the concentration of sodium chloride contained in seawater is about 3% by weight. Until then, sodium chloride can be suitably mixed. In other words, if sodium chloride is mixed up to this level, the load on the environment can be made particularly small.

  In particular, it is particularly effective to mix an inorganic salt as an additive when the acidity of the acidic group contained in the organic acid in the wastewater is low. The reason is presumed as follows according to the study by the present inventors.

  Such an acidic group usually has a low ratio of forming an ionic bond with a trivalent metal ion. Therefore, for example, by mixing the inorganic salt (for example, sodium chloride, potassium chloride, etc.) with sewage before mixing the acidic polymer compound, the ratio of the organic acid ion-bonded with the trivalent metal ion is increased. Can do. This is because the amount of organic acid that can be dissolved in sewage can be reduced by the effect similar to so-called “salting out”, in which salt is mixed to precipitate organic substances dissolved in water, and the resulting aggregates It is considered that the removal efficiency is increased because the organic acid can be taken into the product. By such an action, it becomes possible to more efficiently remove the organic acid in the sewage.

  Further, as an additive, for example, magnetic powder having magnetism is also preferably exemplified. Although there is no restriction | limiting in particular in the specific kind of magnetic powder, For example, metal powder, such as iron powder, is mentioned. By mixing such magnetic powder into sewage, the magnetic powder is taken into the agglomerates, and the agglomerates from the sewage are collected by using, for example, a magnet for the agglomerates in which the magnetic powder is taken in. There is an advantage that the removal becomes easy.

  In addition, an additive may be mixed individually by 1 type and may mix 2 or more types by arbitrary ratios and combinations. Further, the mixing amount of the additive is arbitrary as long as the effects of the present invention are not significantly impaired, and may be appropriately set according to the kind of the additive.

  Further, the timing of mixing the additive into the sewage and the form thereof are arbitrary as long as the effects of the present invention are not significantly impaired. However, for example, when sodium chloride is mixed as an additive, the aggregate size does not change so much even if sodium chloride is mixed after the aggregate is formed, and there is no possibility that the organic acid removal efficiency is greatly changed. There is sex. Therefore, for example, when sodium chloride is mixed as an additive, sodium chloride is preferably mixed before the aggregate is formed (that is, before the acidic polymer compound and the trivalent metal salt are mixed).

  For example, when magnetic powder is mixed as an additive, the above acidic polymer compound or trivalent metal salt and magnetic powder are mixed in advance to obtain a magnetic substance mixture, and the magnetic substance mixture is mixed with sewage. Is preferred. That is, for example, an acidic polymer compound and magnetic powder can be mixed in advance, and the mixture and the trivalent metal salt can be separately mixed with sewage. Further, for example, an acidic polymer compound premixed with magnetic powder and a trivalent metal salt premixed with magnetic powder may be separately mixed with sewage. However, in any case, since an aggregate is formed at the time when the acidic polymer compound and the trivalent metal salt are mixed, it is difficult to contain the magnetic powder in the aggregate, and thus the aggregate is generated. It is particularly preferred to mix the magnetic powder before.

  Furthermore, when an acid or a base is mixed with clean water in order to adjust the pH of sewage (that is, clean water) after removing aggregates, which will be described later, it is preferable to mix the acid or base after removing the aggregates.

[1-7. pH]
Since the sewage to which the sewage purification method according to this embodiment is applied contains an organic acid, it is usually acidic (that is, pH is 7 or less). Especially, when the pH of the sewage to which the sewage purification method according to this embodiment is applied is 5 or more and 7 or less, the organic acid removal rate is particularly high, which is preferable.

  However, when a trivalent metal salt or an acidic polymer compound is mixed with sewage, the sewage tilts toward the acid side (that is, the pH decreases). Therefore, from the viewpoint of allowing the aggregates to exist more stably in the sewage (usually the pH is 2 or more and 5 or less and the aggregates exist more stably), trivalent metal salts and acidic polymer compounds are used. It is preferable to adjust the pH to 5 or more and 7 or less before mixing with sewage. That is, [1-4. As described in [Mixing Order], it is preferable to first mix the acidic polymer compound with the sewage, and then mix the trivalent metal salt. In such a case, the acidic polymer compound is added to the sewage. It is preferable to adjust the pH before mixing. Even if the trivalent metal salt is mixed first, it is preferable to adjust the pH first as well.

  In addition, as described above, since aggregates in wastewater are usually present stably when pH is 2 or more and 5 or less, the removal of aggregates may be performed at such pH. Therefore, the pH of the sewage (that is, clean water) after removing aggregates may be 2 or more and 5 or less. If such clean water is discharged directly into a river, for example, there is a high possibility that the load on the environment will be large, so it may be discharged after the pH is close to the neutral side before discharging into the river, etc. preferable. Specifically, it is preferable to adjust the pH of the clean water to 5 or more and 7 or less.

  In addition, there is no restriction | limiting in particular in the adjustment method of said pH, However, It is preferable to carry out using an inorganic acid or an inorganic base.

[1-8. Other matters]
“Mixing” in the sewage purification method according to the present embodiment includes not only the meaning of “mixing” by, for example, a stirring means, but also the meaning of “addition” unless the effect of the present invention is significantly impaired. The meaning of “mixed” is to be interpreted in the broadest sense. That is, if the sewage and at least the acidic polymer compound and the trivalent metal salt are present in the same system, they are included in the technical scope of the sewage purification method according to this embodiment.

  However, from the viewpoint of improving the removal efficiency of the organic acid, it is preferable to stir the sewage or the like by, for example, stirring means or the like instead of simple mixing. As the degree of stirring, the organic acid can be more efficiently removed as an aggregate by stirring as vigorously as possible. However, if the agitation is too intense, the agglomerates may be crushed and the size of the agglomerates may be too small. As a result, there is a possibility that, for example, the filtration layer used for removing aggregates from the sewage is likely to be clogged, resulting in a reduction in processing speed. Further, for example, even when a filtration layer is not used, fine aggregates are excessively increased, and there is a possibility that the time and effort required for removal become unnecessarily large. Therefore, it is preferable that the degree of stirring is such that the aggregates are not excessively pulverized.

  Further, according to the study by the present inventors, when suspended substances such as sand and oil droplets (contaminated fine particles) coexist in the sewage, such suspended substances are taken into the aggregates, and It was found that enlargement is likely to occur. Among these, when sand having a large specific gravity is taken into the aggregate, the aggregate has a large specific gravity and tends to precipitate. Therefore, it was also found that the aggregate can be removed more suitably by precipitating the aggregate in, for example, a sedimentation tank and filtering the obtained supernatant.

  Further, since oil droplets and the like that can be contained in the sewage are also taken into the aggregates, it is not necessary to perform the method using polyaluminum chloride and polyacrylamide (see FIG. 10), which is a conventional oil droplet removal method, There are advantages that the purification cost can be reduced and the processing time can be shortened.

  Further, for example, in a method for removing an organic acid using an ion exchange resin, the ion exchange resin traps an organic acid on an amino group on the surface of a resin particle having a particle diameter of about 0.1 to 2 mm. Therefore, the smaller the particle diameter of the resin particles, the larger the surface area of the particles, so that more organic acids can be trapped. However, in the sewage purification method according to the present embodiment, since the acidic polymer compound to be mixed and the trivalent metal salt are in a dissolved state in water, an ion exchange resin having a particle size of several angstroms is used. The organic acid can be removed with high efficiency similar to the case. Therefore, compared with the case where the ion exchange resin using the particle | grains whose particle diameter is about 0.1-2 mm is used, an organic acid can be removed from waste water with much higher efficiency.

  Moreover, since the pores existing on the surface of the reverse osmosis membrane used conventionally are much smaller than the voids present in the filtration layer, there is a problem that the pores are easily clogged by the pollutant contained in the sewage. However, the sewage purification method according to the present embodiment has an advantage that such polluted substances are also taken in by the aggregates, so that such a problem does not exist, and sewage can be treated at high speed and in large quantities. .

[2. Flocculant]
The flocculant according to the present embodiment is a flocculant capable of removing the organic acid by mixing with sewage containing an organic acid, and is a water-soluble polymer compound having an acidic group that is mixed with the sewage. (Acid polymer compound) and a trivalent metal salt mixed separately with the water-soluble polymer compound having the acid group with respect to the sewage.

  Regarding sewage, acidic polymer compounds and trivalent metal salts, [1. Since it is the same as that of what was described in the wastewater purification method], description is abbreviate | omitted.

  Moreover, in the coagulant | flocculant which concerns on this embodiment, it is preferable to also provide the magnetic powder mixed with respect to sewage. Also for this magnetic powder, [1. Although it is the same as that of what was described in the sewage purification method], the magnetic powder with which the coagulant | flocculant which concerns on this embodiment is provided is mixed with respect to said sewage. In addition, also about a magnetic powder, for example, a suitable example etc. [1. Since it is the same as that of what was described in the wastewater purification method], description is abbreviate | omitted.

[3. Sewage purification equipment]
Next, the sewage purification apparatus according to the present embodiment will be specifically described with reference to seven embodiments. However, the sewage purification apparatus according to the present embodiment is not limited to the content described below, and can be implemented by arbitrarily changing it within a range that does not impair the gist of the present invention.

[3-1. First embodiment]
FIG. 2 is a diagram schematically illustrating the sewage purification apparatus according to the first embodiment. The sewage purification apparatus 100 according to the first embodiment is a sewage purification apparatus that removes organic acids contained in sewage, and has a high acidity that adds a water-soluble polymer compound (acidic polymer compound) having an acidic group to the sewage. It comprises a molecular compound addition means, a metal salt addition means for adding a trivalent metal salt to the sewage, and an aggregate removal means for removing the generated aggregate from the sewage.

  With reference to FIG. 2, the flow of sewage and a method for removing organic acids and aggregates from the sewage will be described. In FIG. 2, the black arrow is the supply direction of sewage, and the white arrow is the discharge direction of clean water (after removing aggregates from the sewage).

  First, sewage is supplied to the first mixing tank 23 through the pipe 22. At this time, the supply amount of sewage is adjusted by a pump 21 having a function as a supply amount adjusting valve (hereinafter, all pumps have the same function). The mixing tank 23 is provided with pH measuring means (not shown) for measuring the pH of the sewage.

  The pH of the sewage supplied to the first mixing tank 23 is measured by the pH measuring means. When the measured pH is greater than 7, hydrochloric acid is supplied from the hydrochloric acid tank 25a to the first mixing tank 23 via the pump 26a and the pipe 26 so that the pH of the sewage is 5 or more and 7 or less. Similarly, when the pH of the sewage is less than 5, the sodium hydroxide aqueous solution is supplied from the sodium hydroxide aqueous solution tank 25b via the pump 26b and the pipe 27 so that the pH of the sewage is 5 or more and 7 or less. It is supplied to the mixing tank 23. Accordingly, the hydrochloric acid tank 25a and the sodium hydroxide aqueous solution tank 25b function as acid-base addition means.

  In addition, sewage shall be always stirred by the overhead stirrer 24 provided in the 1st mixing tank 23. FIG.

  The acidic polymer compound is supplied from the acidic polymer compound tank (acid polymer compound addition means) 28 through the pump 29 and the pipe 30 to the sewage whose pH is adjusted as described above. The supply amount at this time is the above [1-5. What is necessary is just to mix so that it may become the quantity as described in [mixing quantity]. Then, the sewage mixed with the acidic polymer compound 28 in the first mixing tank 23 is supplied to the second mixing tank 33 via the pump 31 and the pipe 32. The second mixing tank 33 is also provided with an overhead stirrer 34 as in the first mixing tank 23 so that the sewage is always stirred.

  The sewage mixed with the acidic polymer compound supplied to the second mixing tank 33 is supplied from the trivalent metal salt aqueous solution tank (metal salt adding means) 35 through the pump 36 and the pipe 37 to the second. A trivalent metal salt aqueous solution is supplied to the mixing tank 33. In addition, the front-end | tip part 42 of the piping 37 is formed so that the front-end | tip direction may spread as shown in FIG. This is because the trivalent metal salt aqueous solution reaches the surface of the sewage and, at the same time, contains organic acid and begins to aggregate. Therefore, if it supplies to the surface of a sewage of a narrow range, the supplied trivalent metal salt aqueous solution will be included in the aggregate, and even if the said aqueous solution is supplied, there is a possibility that it will not be utilized for further aggregate formation. Therefore, by forming the tip portion 42 in this manner, the trivalent metal salt aqueous solution can be supplied to a wide range of sewage liquid surfaces, and aggregates can be generated more efficiently.

  As described above, when the acidic polymer compound and the trivalent metal salt are mixed with the sewage, an aggregate is generated. Therefore, when one valve 38 (left side in FIG. 2) provided at the lower part of the second mixing tank 33 is opened, the sewage flows together with the aggregates into the filtration unit (aggregate removing means) 39. The filtration part 39 is constituted by a filtration layer 40 and a porous layer 41. The filtration layer 40 is sand, and when the sewage containing the aggregate reaches the filtration layer 40, the aggregate is not permeated through the filtration layer 40 and is accumulated on the upper part thereof. Thereafter, the sewage from which the aggregate has been removed further passes through the porous layer 41 and is discharged as clean water from the sewage cleaning apparatus 100 according to the first embodiment.

  In addition, in the sewage purification apparatus 100 which concerns on 1st embodiment, the two filtration parts 39 are provided. With this configuration, when the filtration layer is clogged and the filtration rate is reduced while the aggregate is first removed by the left filtration unit 39, the left valve 38 is closed and the right valve is closed. By opening 38, it is possible to switch to the right filtration unit 39 to filter sewage and remove aggregates. Then, by performing a treatment such as exchanging the left filtering unit 39 during the filtering process in the right filtering unit 39, it is possible to prevent the filtration processing speed from being reduced as much as possible.

  Moreover, in the sewage purification apparatus 100 which concerns on 1st embodiment, the front-end | tip part of the piping 32 and the front-end | tip part 42 of the piping 37 are comprised so that the liquid level of sewage may not be contacted. By comprising in this way, it can prevent that the aggregate produced | generated in the 2nd mixing tank 33 adheres to said front-end | tip part, and obstruct | occludes piping.

[3-2. Second embodiment]
FIG. 3 schematically shows the sewage purification apparatus 200 according to the second embodiment. Since the thing similar to the sewage purification apparatus 100 shown in FIG. 2 is represented with the same code | symbol, the description is abbreviate | omitted.

  In the sewage purification apparatus 200 which concerns on 2nd embodiment, it has the sedimentation tank 43 instead of the filtration part 39 in the sewage purification apparatus 100 which concerns on 1st embodiment. The sewage containing the agglomerates from the second mixing tank 33 is supplied to the settling tank 43, and the agglomerates 8 having a high specific gravity are precipitated in the settling tank 43, and their supernatant is discharged from the sewage purification apparatus 200 as clean water. It has become so. In addition, in the sewage purification apparatus 200 which concerns on 2nd embodiment, it is set as the structure settling in two steps, and is set as the structure which precipitates the aggregate 8 more reliably. Then, when the aggregate 8 is accumulated to some extent in the sedimentation tank 43 on one side, the sedimentation tank 43 for precipitating the aggregate 8 is replaced by the operation of the valve 38 in the same manner as in the case of the sewage purification apparatus 100 according to the first embodiment. It is possible to prevent the speed from being reduced as much as possible. Although not shown in FIG. 3, the supernatant from the sedimentation tank 43 may be further filtered, and the obtained filtrate may be used as clean water. In this case, as the filtration layer for filtering the supernatant, for example, the above-described aggregate removing means can be applied.

[3-3. Third embodiment]
FIG. 4 schematically shows the sewage purification apparatus 300 according to the third embodiment. Since the thing similar to the sewage purification apparatus 100 shown in FIG. 2 is represented with the same code | symbol, the description is abbreviate | omitted.

  In the sewage purification apparatus 300 according to the third embodiment, a disk-shaped disk 44 having irregularities and holes on the surface is provided on the upper part of the filtration layer 40 constituting the filtration unit 39. The disk 44 is connected to the filter layer stirring means 45 by a stirring shaft. The filter layer stirring means 45 has a function of rotating the disk 44 and also has a function of moving the disk 44 in the vertical direction.

  If the sewage containing aggregates is continuously filtered, the surface of the filtration layer 40 may be clogged with aggregates, and the filtration rate may decrease. Therefore, in such a case, the agglomerates accumulated on the upper surface of the filtration layer 40 are agitated by rotating and vertically moving the disk 44. Thereby, the clogging by the aggregate of the filtration layer 40 can be eliminated, and filtration can be performed smoothly.

[3-4. Fourth embodiment]
FIG. 5 schematically shows the sewage purification apparatus 400 according to the fourth embodiment. Since the thing similar to the sewage purification apparatus 100 shown in FIG. 2 is represented with the same code | symbol, the description is abbreviate | omitted.

  The sewage purification apparatus 400 according to the fourth embodiment includes magnetic powder addition means for adding magnetic powder to the sewage and separation means for separating the aggregates from the sewage by a magnetic separation method. In the sewage purification apparatus 400, trivalent metal salt aqueous solution (contained in the metal salt aqueous solution tank 65) and magnetic powder (contained in the magnetic powder tank 68) are mixed in advance (mixing means for mixing them). Is not shown in FIG. 5), and the mixture is added to sewage containing an acidic polymer compound via a pump 66 and a pipe 67. By comprising in this way, a magnetic powder can be mixed with an aggregate, without producing the bias | inclination in the density per unit volume of the magnetic powder contained in an aggregate. Therefore, in the sewage purification apparatus 400 shown in FIG. 5, the magnetic powder tank 68 functions as a magnetic powder addition means. Such an effect can also be obtained by mixing magnetic powder in the first mixing tank 23.

  Also, the distal end portion of the pipe 67 is formed so that the distal end direction is expanded similarly to the distal end portion 42 described above, and the distal end portion of the pipe 32 and the distal end portion 73 of the pipe 67 are in contact with the liquid level of the sewage. It is configured not to. The reason is the same as the reason explained in the sewage purification apparatus 100 according to the first embodiment.

  The drum 69 is magnetized, and the drum 69 functions as a separating means. The drum 69 has a hole formed on the surface thereof, that is, is formed in a mesh shape. In addition, since the size of the formed hole is smaller than the size of the generated aggregate, the aggregate is not discharged to the outside through the hole. Accordingly, the agglomerates containing the magnetic powder generated in the second mixing tank 33 are adsorbed on the drum 69. The drum 69 in the sewage purification apparatus 400 rotates clockwise, and the adsorbed agglomerates are scraped off by the scraper 70 and collected in the agglomerate accumulation container 71 whose lower surface is formed in a mesh shape. It is like that. Since the scraped off agglomerate contains a lot of water (clean water), it is discharged to the outside of the sewage purification apparatus 400 through a mesh provided under the agglomerate accumulation container 71.

  Further, since the aggregates adsorbed on the drum 69 contain a lot of water (clean water) as well, such clean water is connected to the central portion of the drum 69 through a mesh provided on the surface of the drum 69. Through the pipe 72, the wastewater purification device 400 is discharged to the outside.

  In addition, as a modification of the sewage purification apparatus 400 according to the fourth embodiment, a configuration may be employed in which a sedimentation tank is provided without providing the magnetic drum 69. Aggregates containing magnetic powder are more likely to settle due to their large specific gravity. For example, after most of the aggregates are settled in a sedimentation tank, the sewage containing the remaining aggregates (ie, the supernatant) may be filtered. Good. By doing so, it is possible to purify sewage without performing magnetic separation.

[3-5. Fifth embodiment]
FIG. 6 schematically shows the sewage purification apparatus 500 according to the fifth embodiment. Since the thing similar to the sewage purification apparatus 100 shown in FIG. 2 and the sewage purification apparatus 400 shown in 4th Embodiment shown in FIG. 5 is represented with the same code | symbol, the description is abbreviate | omitted.

  In the sewage purification apparatus 500 according to the fifth embodiment, a magnetic drum 74 is further provided in addition to the magnetic drum 69. Similarly to the drum 69, the drum 74 is also provided to be rotatable clockwise. As described above, the clean water is discharged to the outside through the holes formed on the surface of the drum 69. However, in the sewage purification apparatus 500 according to the fifth embodiment, the water flows from the inside of the drum 69 toward the drum 74. Is configured to erupt. By causing water to be ejected from the inside of the drum 69 in the direction of the drum 74, aggregates adsorbed on the drum 69 can be adsorbed on the drum 74.

  Since no hole is formed on the surface of the drum 74, that is, it is formed of a smooth metal plate instead of a mesh shape, the scraper 70 is not caught by the hole when the surface of the drum 74 is scratched with the scraper 70. There is no possibility of damage.

[3-6. Sixth embodiment]
FIG. 7 schematically shows a sewage purification apparatus 600 according to the sixth embodiment. Since the thing similar to the sewage purification apparatus 100 shown in FIG. 2 and the sewage purification apparatus 500 shown in 4th Embodiment shown in FIG. 6 is represented with the same code | symbol, the description is abbreviate | omitted.

  In the sewage purification apparatus 600 according to the sixth embodiment, the magnetic separation is not performed in the second mixing tank 33 but in another tank (aggregate removing tank 75). That is, sewage is supplied to the aggregate removal tank 75 together with the aggregate generated in the second mixing tank 33 (the supply amount can be performed by the valve 76), and is separated by a separation means provided in the aggregate removal tank 75. Clean water can be discharged to the outside.

  By configuring the sewage purification apparatus 600 in this way, the aggregate containing the magnetic powder is likely to settle as described above. Therefore, the aggregate generated in the second mixing tank 33 is in the second mixing tank 33. The amount of agglomerate that precipitates at the bottom and is supplied to the agglomerate sedimentation tank 75 is small. Accordingly, the drum 69 is less likely to be clogged, and an advantage that maintenance of the drum 69 can be reduced is obtained.

[3-7. Seventh embodiment]
FIG. 8 schematically shows the sewage purification apparatus 700 according to the seventh embodiment. Since the thing similar to the sewage purification apparatus 100 shown in FIG. 2 and the sewage purification apparatus 500 shown in 5th Embodiment shown in FIG. 6 is represented with the same code | symbol, the description is abbreviate | omitted. However, the drum 74 in the sewage purification apparatus 700 according to the seventh embodiment is configured to rotate counterclockwise.

  In the sewage purification apparatus 700 according to the seventh embodiment, the aggregate removal tank 77 is provided in the same manner as the sewage purification apparatus 600. However, unlike the case of the aggregate removal tank 75 in the sewage purification apparatus 600, the distance between the bottom of the aggregate removal tank 77 and the drum 74 is short. Therefore, the agglomerates contained in the sewage can be adsorbed to the drum 74 almost completely. Therefore, the aggregate can be removed almost completely with one drum, and the space for the sewage purification apparatus 600 can be saved.

[4. Oil extraction system]
Next, an example of an oil extraction system using the above sewage purification apparatus will be described with a specific example. FIG. 9 is a diagram schematically illustrating the entire oil extraction system according to the present embodiment. As shown in FIG. 9, the oil extraction system according to the present embodiment generates the water from the sewage purification device 83, oil extraction means 81 that extracts oil from the oil sand by blowing water vapor into the oil sand, and water vapor. Water vapor generating means 85, and using the heat generated by burning the agglomerates, the clean water after removing the agglomerates is converted into water vapor.
In FIG. 9, black arrows indicate dirty water, white arrows indicate clean water or clean water vapor, and diagonal arrows indicate the flow of aggregates. Moreover, although the flow of the extracted oil is not shown in the figure, it is usually subjected to an essential oil process described later.

  The oil content extraction means 81 extracts oil content from the oil sand by blowing water vapor into the oil sand. As a specific configuration, any known extraction method can be used. In the oil extraction means 81, when the water vapor is blown into the oil sand, the oil is heated to lower the viscosity, and the water is separated from the sand as contaminated water in which the water derived from water vapor and the oil are mixed. . Such polluted water is allowed to stand to separate into an oil layer and an aqueous layer due to a difference in specific gravity, and an oil layer is recovered from the oil sand by collecting an upper oil layer (so-called “pichumen”). Can be extracted. The extracted oil is separated into, for example, naphtha, gasoline, heavy oil, asphalt and the like by the difference in boiling point in the essential oil process and used in various industries.

  On the other hand, a lower layer of water (sewage) contains a large amount of the organic acid. Therefore, in such sewage, the organic acid is removed by the sewage purification device 83 in order to reduce the load on the environment. In addition, although the sewage purification apparatus 83 with which the oil extraction system which concerns on this embodiment is equipped is said sewage purification apparatus, it is not limited to said specific example, In the range which does not impair the summary of this invention, it is arbitrary. The changed sewage purification apparatus can be used.

  The water vapor generating means 85 converts water into water vapor for extracting oil from the oil sand. As a specific configuration, any known extraction method can be used, but it is preferable to use clean water discharged from the sewage purification apparatus 83 as shown in FIG. In the oil extraction system according to the present embodiment, liquid water is converted into gaseous water (steam) using heat generated by burning the aggregate discharged from the sewage purification apparatus 83. ing. Since the aggregate contains an organic acid, an acidic polymer compound, and the like as described above, it can be suitably used as part of the fuel for generating water vapor, and there is an advantage that waste can be reduced. The means for transferring aggregates from the sewage purification device 83 to the water vapor generating means 85 is not particularly limited, and for example, a belt conveyor or the like can be used.

  Hereinafter, the present embodiment will be described in more detail with reference to examples. However, the present embodiment is not limited to the following examples, and may be arbitrarily modified without departing from the scope of the present invention. Can do.

A “simulated sewage” was prepared using naphthenic acid as an organic acid.
Naphthenic acid is a general term for compounds in which a carboxyl group is bonded to a cyclic hydrocarbon, and the molecular weight varies depending on the size of the ring and the presence or absence of branched alkyl chains. The naphthenic acid used in this example was a commercial product manufactured by Tokyo Chemical Industry Co., Ltd., and its average molecular weight was 220. The carboxyl group (acidic group) contained in this naphthenic acid was made into an ammonium salt structure, and 1 L of simulated sewage water in which naphthenic acid was dissolved at a concentration of 220 ppm (the amount of naphthenic acid contained was 1 mmol) was prepared. The pH of this simulated sewage was 6.9.

Example 1
While stirring the simulated sewage, 1.44 g of a 5 wt% aqueous solution of polyacrylic acid having a carboxyl group as the acidic polymer compound (number average molecular weight is 250,000) (1 mmol as the amount of the carboxyl group contained in the aqueous solution) In addition, it was stirred well. Thereafter, 1.62 g of a 10% by weight aqueous solution of iron (III) chloride as a trivalent metal salt (1 mmol as the amount of iron (III) ions contained in the aqueous solution) was added to form aggregates. The aggregate was collected by filtration, and the amount of naphthenic acid contained in the filtrate was quantified by measuring the TOC (Total Organic Carbon) concentration of the filtrate. Specifically, the TOC concentration was measured according to JIS K0102 “combustion oxidation-infrared analysis method”. In addition, as a TOC concentration measuring device, a total organic carbon meter TOC-5000 (manufactured by Shimadzu Corporation) was used.
Since the obtained TOC concentration represents the amount of carbon contained in the simulated sewage, it is assumed that the simulated sewage contains no carbon other than naphthenic acid-derived naphthenic acid. Quantified. As a result, the concentration of naphthenic acid contained in the filtrate was 10 ppm (the amount in 1 L of simulated sewage was 45 μmol).
Further, when the same filtrate was quantified by high performance liquid chromatography, the naphthenic acid concentration was 10 ppm. Therefore, in the following naphthenic acid concentration measurement, naphthenic acid in the filtrate was quantified by measuring a simpler TOC concentration.
And the removal efficiency was computed according to the following formula | equation (2).

Removal efficiency (%) = 100 − {(Amount of naphthenic acid contained in filtered aqueous solution) / (Amount of naphthenic acid contained in simulated sewage)} × 100 (2)

As a result, the removal efficiency was 95%. The results are summarized in Table 1.

(Example 2)
Aggregate filtration was carried out in the same manner as in Example 1, except that 2 g of 10 wt% aqueous iron sulfate solution (1 mmol as the amount of iron (III) ions) was used instead of 10 wt% aqueous solution of iron (III) chloride. The concentration of naphthenic acid in the subsequent aqueous solution and the removal efficiency were determined. As a result, the naphthenic acid concentration was 10 ppm, and the removal efficiency was 95%.

(Example 3)
Aggregate filtration was carried out in the same manner as in Example 1 except that 1.06 g of a 10 wt% polyaluminum chloride aqueous solution (1 mmol as the amount of aluminum ions) was used instead of the 10 wt% aqueous solution of iron (III) chloride. The concentration of naphthenic acid in the subsequent aqueous solution and the removal efficiency were determined. As a result, the naphthenic acid concentration was 10 ppm, and the removal efficiency was 95%.

Example 4
After filtering aggregates in the same manner as in Example 1, except that 1.71 g of 10 wt% aqueous aluminum sulfate solution (1 mmol as the amount of aluminum ions) was used instead of the 10 wt% aqueous solution of iron (III) chloride. The concentration of naphthenic acid in the aqueous solution and the removal efficiency were determined. As a result, the naphthenic acid concentration was 10 ppm, and the removal efficiency was 95%.

表１より、鉄やアルミニウム等の三価の金属の塩酸塩、あるいは硫酸塩といった金属塩を用いることにより、ナフテン酸を高効率で除去可能であることが明らかとなった。 Table 1 summarizing the above results is shown below.

From Table 1, it was revealed that naphthenic acid can be removed with high efficiency by using a metal salt such as a salt of a trivalent metal such as iron or aluminum or a sulfate.

(Examples 5-7)
The concentration and removal of naphthenic acid in the aqueous solution after filtration of the aggregates in the same manner as in Example 1 except that the amount of the iron (III) chloride 10% by weight aqueous solution was changed to 1.08 g, 1 g, and 0.9 g. Efficiency was determined (Examples 5-7, respectively). The results are shown in Table 2.

※ 表２中、「鉄イオン量」とは、混合した塩化鉄（III）水溶液中の鉄（III）イオンの物質量である。

* In Table 2, “Amount of iron ions” is the amount of iron (III) ions in the mixed aqueous solution of iron (III) chloride.

  Since iron ions contained in the aqueous solution are trivalent, up to three carboxyl groups of naphthenic acid and polyacrylic acid can be captured by ionic bonds. Since the total amount of naphthenic acid and polyacrylic acid carboxyl groups in the simulated wastewater is 2 mmol, theoretically, iron ions should be at least 0.67 mmol, which is 1/3 of the number of moles.

  The results shown in Table 2 also support this, and when the iron (III) chloride aqueous solution mixing amount is 1.08 g (Example 5), the mixed iron (III) ion is 0.67 mmol, so it is simulated. It was possible to reduce the concentration of naphthenic acid in sewage to 10 ppm. However, when there are fewer iron (III) ions (Examples 6 and 7), there is not enough iron (III) ions to capture naphthenic acid, so the removal efficiency of simulated sewage naphthenic acid is Although still high, the removal efficiency gradually decreased. Therefore, it has been found that the removal efficiency is improved particularly when the above formula (1) is satisfied.

(Example 8)
When preparing simulated sewage, the concentration of naphthenic acid in the aqueous solution after filtration of the aggregates and the removal efficiency were determined in the same manner as in Example 1 except that naphthenic acid was used as a sodium salt structure instead of an ammonium salt structure. At this time, the pH of the simulated sewage was 7.7. As a result, the naphthenic acid concentration was 30 ppm, and the removal efficiency was 86%.

(Examples 9 to 14)
Example 8 except that simulated sewage whose pH was adjusted to 7.1, 6.9, 6.2, 5.1, 4.9, 4.5 by adding 10 wt% hydrochloric acid to the simulated sewage was used. In the same manner as described above, the naphthenic acid concentration in the aqueous solution after filtration of the aggregates and the removal efficiency were determined. Moreover, the pH of the sewage (clean water) after the aggregate removal was also determined. The results are shown in Table 3.

  From the results in Table 3, it was found that the organic acid removal efficiency was particularly improved by adjusting the pH of the sewage to 5 to 7 in advance before the aggregate formation.

  By the way, the pH of the clean water shifts to the acidic side due to the influence of the iron chloride used. If the acidity becomes too high, there is a possibility of corrosion when various pipes passing thereafter are made of metal. In addition, when mixed in rivers and groundwater, high acidity may affect the ecosystem. Therefore, by adding a basic substance such as sodium hydroxide or potassium hydroxide to the filtrate after the coagulation removal, the liquidity is adjusted from weakly acidic to neutral, so that these concerns can be solved. Specifically, it is desirable to adjust the pH to 5-7.

Actually, corrosion of piping such as SUS could be prevented by adding 10% by weight sodium hydroxide aqueous solution to the clean water to adjust the pH to 5-7. In addition, as a result of the microtox test for examining acute toxicity, the fluorescence intensity due to the bacteria used in the test hardly decreased by adjusting the liquidity to pH 5-7.
From the above results, it has been clarified that by adjusting the pH of clean water to 5 to 7, the acute toxicity of clean water can be reduced or the corrosion of piping by clean water can be prevented.

(Example 15)
Aggregation was carried out in the same manner as in Example 1 except that 1.72 g of a 5 wt% aqueous solution of polymethacrylic acid (1 mmol as the amount of carboxyl group) was used instead of 1.44 g of a 5 wt% aqueous solution of polyacrylic acid. The concentration of naphthenic acid in the aqueous solution after the product filtration and the removal efficiency were determined. As a result, the naphthenic acid concentration was 10 ppm, and the removal efficiency was 95%. Therefore, it has been clarified that even when polymethacrylic acid is used as the acidic polymer compound instead of polyacrylic acid, the organic acid dissolved in the sewage can be removed.

(Example 16)
Example 1 except that 1.84 g of a 10 wt% aqueous solution of polystyrene sulfonic acid (1 mmol as the amount of sulfonic acid group) was used instead of 1.44 g of a 5 wt% aqueous solution of polyacrylic acid, The concentration of naphthenic acid in the aqueous solution after filtration of the aggregates and the removal efficiency were determined. As a result, the naphthenic acid concentration was 10 ppm, and the removal efficiency was 95%. Therefore, it has been clarified that even when a water-soluble polymer having a sulfonic acid group is used as the acidic polymer compound, the organic acid dissolved in water can be removed.

(Example 17)
The concentration of naphthenic acid in the aqueous solution after filtration of the aggregates and the removal efficiency were determined in the same manner as in Example 1 except that 10 g of a 5.85% by weight sodium chloride aqueous solution was added before adding the aqueous solution of iron (III) chloride. It was. As a result, the naphthenic acid concentration was 6 ppm, and the removal efficiency was 97%. Therefore, it became clear that the removal efficiency of organic acid can be further improved by mixing sodium chloride.

(Example 18)
The concentration of naphthenic acid and the removal efficiency in the aqueous solution after the aggregate filtration were determined in the same manner as in Example 17 except that the amount of the 5.85 wt% sodium chloride aqueous solution was 30 g. As a result, the naphthenic acid concentration was 5 ppm, and the removal efficiency was 98%. Therefore, it has been clarified that the organic acid removal efficiency can be further improved by increasing the amount of sodium chloride to be mixed.

(Example 19)
Concentration and removal of naphthenic acid in the aqueous solution after filtration of the aggregates in the same manner as in Example 17, except that 10 g of 7.45 wt% potassium chloride aqueous solution was used instead of 10 g of 5.85 wt% sodium chloride aqueous solution. We asked for efficiency. As a result, the naphthenic acid concentration was 6 ppm, and the removal efficiency was 97%.

(Example 20)
The concentration of naphthenic acid and the removal efficiency in the aqueous solution after filtration of the aggregates were determined in the same manner as in Example 17 except that 20 g of a 6 wt% magnesium sulfate aqueous solution was used instead of 10 g of the 5.85 wt% sodium chloride aqueous solution. Asked. As a result, the naphthenic acid concentration was 6 ppm, and the removal efficiency was 97%.

  From the results of Examples 17 to 20, it was revealed that the removal efficiency of organic acid can be further improved by adding various inorganic salts.

(Example 21)
In Example 1, an iron (III) chloride aqueous solution and ferrite-based magnetic powder 100 mg were mixed, and then the mixture was added to simulated sewage. After the agglomerates were formed, when a permanent magnet was put in the simulated sewage and pulled up 30 seconds later, about 90% of the agglomerates adhered to the magnet surface. The remaining agglomerates were stuck to the inner wall of the mixing tank. The concentration of naphthenic acid in the simulated sewage (clean water) after removing the aggregates was 10 ppm, and the removal efficiency was 95%.

From the above, it has been clarified that by using magnetic powder, organic acid can be removed from wastewater without filtration.
Similar results were obtained even when the acidic polymer compound and the magnetic powder were mixed instead of the iron (III) chloride aqueous solution and the mixture was mixed with simulated sewage.

(Comparative example)
As a comparative example, a conventionally used technique shown in FIG. 10 was performed.
While stirring 1 L of the simulated waste water, 1.71 g of a 10 wt% polyaluminum chloride aqueous solution (1 mmol as the amount of aluminum ions) was added. As a result, the simulated sewage was slightly turbid, but no precipitation occurred.

  Thereafter, 7.1 g of a 1 wt% aqueous solution of polyacrylamide (number average molecular weight: 1000000) (1 mmol as the amount of the repeating unit) was added. However, the simulated sewage remained slightly cloudy and no precipitation occurred.

  Therefore, when this simulated sewage was allowed to stand for 24 hours, slight precipitation was observed at the bottom of the container. After removing this precipitate by filtration, the amount of naphthenic acid in the filtrate was measured in the same manner as in Example 1. As a result, the concentration of naphthenic acid was 210 ppm, and the removal efficiency was 5%.

  From the above results, when polyaluminum chloride or polyacrylamide, which is a flocculant that removes substances suspended in water, is used, that is, when conventional technology is used, organic acids dissolved in water are almost completely removed. It became clear that not.

DESCRIPTION OF SYMBOLS 1 Micro flock 2 Contaminated particulate 3 Flock 4 Magnetic powder 5 Organic acid 6 Water-soluble polymer compound (acidic polymer compound) which has an acidic group
7 Trivalent metal salt 8 Aggregate 21, 26a, 26b, 29, 31, 36, 66 Pump 22, 26, 27, 30, 32, 37, 67, 72, 82, 84, 86 Pipe 23 First mixing Tank 24, 34, 64, 68 Overhead stirrer 25a Hydrochloric acid tank (acid-base addition means)
25b Sodium hydroxide aqueous solution tank (acid-base addition means)
28 Acidic polymer aqueous solution tank (Acid polymer compound addition means)
33 Second mixing tank 35 Trivalent metal salt aqueous solution tank (metal salt addition means)
38 Valve 39 Filtration part (aggregate removing means)
40 Filtration layer 41 Porous layer 42 Tip portion 43 Sedimentation tank 44 Disc 45 Filtration layer stirring means 65 Trivalent metal salt aqueous solution tank (metal salt addition means)
68 Magnetic powder tank (means for adding magnetic powder)
69,74 drums (separation means)
70 Scraper 71 Aggregate Accumulation Container 73 Tip 75 Aggregate Removal Tank 76 Valve 77 Aggregate Removal Tank 81 Oil Extraction Plant 83 Sewage Purifier 85 Steam Generater 87 Belt Conveyor 100, 200, 300, 400, 500, 600, 700 Sewage purification equipment

Claims (22)

A wastewater purification method for removing organic acids contained in wastewater,
For the sewage, a water-soluble polymer compound having an acidic group and a salt of iron (III) and an inorganic acid are separately mixed to produce an aggregate containing the organic acid,
A method for purifying sewage, wherein the organic acid contained in the sewage is removed by removing the aggregates. The method for purifying sewage according to claim 1, wherein the acidic group is a carboxyl group. The method for purifying sewage according to claim 1 or 2 , wherein the water-soluble polymer compound having an acidic group is polyacrylic acid. The method for purifying sewage according to any one of claims 1 to 3 , wherein the water-soluble polymer compound having an acidic group has a number average molecular weight of 2,000 to 1,000,000. The sewage purification method according to any one of claims 1 to 4 , wherein magnetic powder is mixed with the sewage. Wherein the acidic group is characterized by forming the ammonium or alkali metal salts, sewage purification method according to any one of claims 1-5. The number of moles of metal ions contained in the salt of iron (III) and inorganic acid in the wastewater is M, the number of moles of acidic groups contained in the water-soluble polymer compound having an acidic group is PA, and the organic When the number of moles of acid is MA, the salt of iron (III) and inorganic acid and the water-soluble polymer compound having an acidic group are mixed with the sewage so as to satisfy the following formula (1). The method for purifying sewage according to any one of claims 1 to 6 , wherein:
3 × M ≧ MA + PA (1) Mixing the water-soluble polymer compound having an acidic group or the salt of iron (III) with an inorganic acid and the magnetic powder to obtain a magnetic substance mixture, and mixing the magnetic substance mixture into the sewage The sewage purification method according to claim 5 , wherein: The water-soluble polymer compound having an acidic group or the salt of iron (III) and an inorganic acid is previously dissolved in water to obtain an aqueous solution, and the aqueous solution is mixed with the sewage. The wastewater purification method according to any one of to 8 . After adjusting the pH of the sewage to 5 or more and 7 or less, the water-soluble polymer compound having the acidic group, and the salt of iron (III) and inorganic acid are mixed in the sewage, The sewage purification method according to any one of claims 1 to 9 . The sewage purification method according to any one of claims 1 to 10 , wherein the pH of clean water after removing the aggregates is adjusted to 5 or more and 7 or less. The sewage purification method according to claim 10 or 11 , wherein the pH is adjusted using an inorganic acid or an inorganic base. A flocculant capable of removing the organic acid by mixing with wastewater containing the organic acid,
A water-soluble polymer compound having an acidic group, mixed with the wastewater;
Wherein is engaged mixed with respect to sewage, a salt of iron (III) and an inorganic acid,
A flocculant characterized by comprising: 14. The flocculant according to claim 13 , wherein the acidic group is a carboxyl group. 15. The flocculant according to claim 13 or 14 , wherein the water-soluble polymer compound having an acidic group is polyacrylic acid. The flocculant according to any one of claims 13 to 15 , wherein the water-soluble polymer compound having an acidic group has a number average molecular weight of 2,000 to 1,000,000. Further characterized in that it comprises a magnetic powder that is mixed with respect to the sewerage, coagulation agent according to any one of claims 13 to 16. The flocculant according to any one of claims 13 to 17 , wherein the acidic group forms a salt with ammonia or an alkali metal. A sewage purification apparatus for removing organic acids contained in sewage,
Acidic polymer compound addition means for adding a water-soluble polymer compound having an acidic group to the sewage,
Metal salt addition means for adding a salt of iron (III) and an inorganic acid to the sewage,
Agglomerate removing means for removing the agglomerates generated from the waste water;
A sewage purification apparatus, comprising: PH measuring means for measuring the pH of the sewage,
Acid-base addition means for adding an acid or base to the sewage,
The sewage purification apparatus according to claim 19 , comprising: Magnetic powder adding means for adding magnetic powder to the sewage,
Separation means for separating the aggregate from the wastewater by a magnetic separation method;
The sewage purification apparatus according to claim 19 or 20 , characterized by comprising: The sewage purification apparatus according to any one of claims 19 to 21 ,
An oil extraction means for extracting oil from the oil sand by blowing water vapor into the oil sand;
Water vapor generating means for generating the water vapor;
With
An oil extraction system, wherein clean water after removing the aggregates is converted into the water vapor using heat generated by burning the aggregates.

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