JP2013010084A - Water purification process and water purifying apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water purification process for removing organic acids from a large amount of polluted water at high speed, and to provide a water purifying apparatus.SOLUTION: The water purification process includes the steps of: flocculating organic substances in a polluted water by adding a flocculant; and heating the polluted water or a supernatant obtained from the polluted water. The water purifying apparatus includes a unit configured to add a flocculant to a polluted water containing organic substances; and a unit configured to heat the polluted water. The polluted water is supplied to a first mixing tank 23 through a pipe 22 by a pump 21.An aqueous solution of a water-soluble polymer with an acid group is supplied to the first mixing tank through a pipe 30.The liquid from a filtering section 39 is supplied to a heating tank 91.

Description

  The present invention relates to a water treatment process using a flocculant for purifying sewage and a water purifier thereof.

  Sewage generated in oil field mining contains a large amount of organic acids (acetic acid, valeric acid, naphthenic acid, etc.) coexisting with crude oil. When these organic acids are contained in the ocean or rivers, they have a great impact on the ecosystem, so it is necessary to release them after removing these organic acids. However, the amount of generated sewage is enormous, and there is a need for high-speed and large-scale treatment technology. Furthermore, the cost reduction of a processing process and size reduction of a water purifier are calculated | required.

  For example, a method shown in FIG. 1 is known as a method for removing the pollutant fine particles suspended in water.

  Polyaluminum chloride (commonly called PAC) or iron sulfate is added to form micro floc 1 which is a small aggregate having a particle size of about several tens to several hundreds of μm. Thereafter, a polymer such as polyacrylamide is subsequently added to form a large agglomerate called floc 3 having a particle size of approximately several hundred to several thousand μm in the water. The sewage containing the agglomerates is separated and removed through a filtration layer, or the magnetic powder 4 is put at the time of floc formation, and the floc is formed and then separated using magnetism.

  All of these methods can remove contaminating fine particles at high speed, but it is difficult to remove organic acids dissolved in water. For example, some organic acids have a carboxyl group, and the carboxyl group is not free and has an ammonium salt structure, a sodium salt structure, or the like, so that it is more easily dissolved in water. Organic acids include acetic acid, valeric acid, naphthenic acid, and the like, and vary from acids having a low molecular weight (for example, those having a small number of carbon atoms) to acids having a high molecular weight (those having a large number of carbon atoms).

  On the other hand, the organic acid is generally removed by a method of adsorbing to activated carbon, ion exchange resin or the like. It is also possible to remove using a reverse osmosis membrane. For example, Patent Document 1 adsorbs and removes an organic acid using a contact material containing fibrous activated carbon.

JP 2003-144839 A

  On the other hand, when adsorbed on activated carbon or ion exchange resin, the amount of adsorption is determined by the surface area of the activated carbon or ion exchange resin. Therefore, the smaller the particle size, the larger the surface area. However, if it is too small, the activated carbon and the ion exchange resin cannot be retained, which makes handling difficult. Moreover, since activated carbon also adsorbs organic substances other than organic acids, if the oil component adheres prior to the organic acid, the adsorption efficiency is immediately reduced.

  The reverse osmosis membrane cannot be used when the pores on the surface of the membrane are clogged with not only organic acids but also pollutants, so it is difficult to treat a large amount of sewage at high speed.

  Thus, it was difficult to remove organic acids from a large amount of sewage at high speed.

  An object of the present invention is to remove organic acids from a large amount of sewage at high speed.

  The characteristic of this invention for solving the said subject is a water treatment process provided with the process of coagulating the organic substance in wastewater using a flocculant, and the process of heating the said wastewater.

  Another feature of the present invention is a water purifier comprising a mechanism for adding a flocculant to sewage containing organic matter and a mechanism for heating the sewage.

  According to the present invention, an organic acid can be removed from a large amount of sewage at high speed.

This is a conventional method for agglomerating contaminated fine particles. It is a scheme of floc (aggregate) formation. It is a GC analysis result. It is a GC analysis result. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of a water purifier. It is a schematic diagram of an oil extraction and water purification system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the water treatment process of this embodiment, there are two steps for removing the organic acid. That is, a step of removing organic substances as aggregates using a flocculant and a step of volatilizing and removing organic substances in water by heating wastewater. In this embodiment, these two steps are used to remove almost all organic acids in water, specifically, from high molecular weight organic acids to low molecular weight organic acids.

  First, a method for changing an organic acid into an aggregate will be described with reference to FIG. Here, it is represented by a water-soluble polymer having a carboxyl group as an acidic group or an organic acid having a carboxyl group, but the same applies when the acidic group is a sulfonic acid group. As an example of a trivalent metal salt, an iron salt is shown here, but the same applies to other trivalent metals (for example, aluminum, neodymium, etc.).

  First, the water-soluble polymer 6 having a carboxyl group is added to the waste water containing the organic acid 5. Thereby, the water-soluble polymer which has an organic acid and a carboxyl group coexists in waste water. When iron salt 7 is added in this state, iron ions, organic acid carboxyl groups, and water-soluble polymer carboxyl groups are ionically bonded. In this way, a water-insoluble aggregate 8 is formed. In the case of an organic acid alone, iron ions and carboxyl groups of the organic acid are ionically bonded to form a salt, but the molecular weight of the organic acid is about several hundreds, and the average molecular weight of the resulting salt is several hundred to several thousand. Is soluble to some extent in water. Therefore, only a part of the salt is precipitated. However, when iron ions are ion-bonded to the carboxyl group of the water-soluble polymer and the molecular weight of the salt reaches several tens of thousands, it becomes difficult to dissolve in water and most of the salt precipitates. In addition, in the case of a polymer having a very large molecular weight, a portion that is ion-bonded so as to cross-link between iron ions and molecules appears, so that it is more difficult to dissolve in water.

  When a divalent metal salt is used, the crosslink density is low and only a part of the metal trapped by ionic bonds aggregates the organic acid, so in order to aggregate many organic acids, the metal must be trivalent. It is desirable to use it.

  Regarding the order of addition of the trivalent metal salt and the water-soluble polymer having an acidic group, the trivalent metal salt tends to have a higher organic acid removal rate later. When a water-soluble polymer having an acidic group is added later, some of the ions do not ion-bond with iron ions, which may increase the TOC concentration in the sewage. Therefore, it is desirable to add the trivalent metal salt after adding the water-soluble polymer having an acidic group first.

  In addition, when adding a trivalent metal salt and a water-soluble polymer having an acidic group, although it is effective even in bulk, it takes time to spread over the entire sewage, so it is preferably added in the form of an aqueous solution. In particular, if a trivalent metal salt is added before the water-soluble polymer having an acidic group is not sufficiently dissolved, aggregation may occur only partially in sewage and there is a concern that organic acid removal may be insufficient. It is also preferable to add them in the form of aqueous solutions.

  Since the metal ion of the metal salt is ionically bonded to the carboxyl group of the organic acid and the acidic group of the water-soluble polymer having an acidic group, it is desirable to add an amount of the metal salt in which these almost all ionically bond. From this point of view, when M is the number of moles of metal ions of the metal salt to be added, PA is the number of moles of acidic groups of the water-soluble polymer having acidic groups, and MA is the number of moles of organic acid in the sewage, It is desirable to satisfy the inequality.

3xM> MA + PA
The most commonly used ion exchange resin for conventional organic acid removal has an organic acid trapped on an amino group on the surface of a resin particle having a particle diameter of about 0.1 to 2 mm. The smaller the particle size, the larger the surface area of the particles, so that more organic acids can be trapped. However, in the case of the present embodiment, since the flocculant to be added is water-soluble, the organic acid can be trapped with high efficiency in the same manner as using an ion exchange resin having a particle size of several angstroms. Therefore, the amount of the organic acid trap when the same amount is added as compared with the case of using the conventional ion exchange resin is remarkably increased.

  Next, a water treatment process using this flocculant will be described. In this embodiment, a new process using this flocculant is proposed.

  Wastewater (A) containing an organic acid and water (B) treated with a flocculant were analyzed using GC (Gas Chromatography). The results of GC analysis are shown in FIGS. 3 (A) and 3 (B). The vertical axis of the graph is the detection voltage, but is a value proportional to the amount of the detected substance. That is, the higher the detection voltage, the greater the amount of substance detected. The horizontal axis represents the retention time and is generally correlated with the molecular weight of the substance to be detected. That is, a substance detected in a region having a long retention time varies depending on the functional group, but is generally a substance having a high molecular weight (high molecular weight), and a substance detected in a region having a short retention time has a relatively low molecular weight. It is a small (low molecular weight) substance. Moreover, since the organic component in water is extracted with hexane this time and GC analysis is implemented with the concentrate, the output by hexane is detected as a background in the GC analysis result.

  From FIG. 3 (A), in the sewage (A) before treatment, a large peak is detected from a retention time of 10 minutes to a retention time of about 25 minutes. This means that the wastewater contains a large amount of organic substances having a low molecular weight to organic substances having a high molecular weight. On the other hand, in the GC analysis result (FIG. 3B) of water (B) treated with the previous flocculant, it can be seen that the detected peak intensity is greatly reduced. This means that organic substances in the water were almost removed by the flocculant.

  In order to examine in more detail, FIG. 4 shows an enlarged view of the GC analysis result obtained by subtracting the background from hexane. From the analysis result of water (B), a slight peak appears at a retention time of 10 to 15 minutes. In addition, when the holding time is 15 minutes or more, the detection voltage is almost zero. From this graph, the present flocculant can almost completely remove organic substances having a large molecular weight (in a region having a long retention time), but a small amount of organic substances having a small molecular weight (in a region having a short retention time) remain. I understand that.

  Next, a process for removing the remaining low molecular weight organic acid will be described. This water treatment process includes a step of removing organic substances using a flocculant and a step of removing organic substances by heating sewage. If the temperature of sewage goes up, you may heat how.

  A low molecular weight organic substance remaining in water after the coagulant treatment is generally highly volatile because of its low molecular weight. Therefore, by heating the sewage, it is possible to remove such low molecular organic substances by volatilizing them. Some low-molecular organic substances are volatilized even at a temperature of about room temperature, but can be removed from water by heating water to at least the vicinity of its boiling point.

  Therefore, in order to volatilize organic matter positively, the heating temperature is preferably higher than room temperature (40 ° C. or higher), and is preferably less than 100 ° C. in view of the boiling point of water. Furthermore, in oil sand drainage or the like, the drainage temperature itself may be about 60 ° C., so a heating temperature of 60 ° C. or higher is desirable in order to actively remove low molecular weight organic substances.

  In view of improving the energy efficiency of the equipment, it is desirable to recover and reuse the removed low molecular weight organic matter. For example, the low-molecular-weight organic substance recovered is stored in a recovery cabinet and burned using it to obtain a heat source for heating the sewage. By recovering and reusing such low molecular weight organic substances, process costs can be reduced.

  The details of (1) organic matter removal using a flocculant and (2) organic matter removal by heating of sewage are further described below in connection with the water treatment process of this embodiment.

(1) Organic matter removal using a flocculant
(A) Flocculant
(I) Metal salt
Examples of the metal species of the metal salt include trivalent metals such as iron, aluminum, neodymium, and dysprosium. Of these, iron and aluminum are preferred because they are abundant on the earth, inexpensive and easily available. Also, iron is desirable because it is cheaper.

  As the iron salt, a structure in which the salt itself does not contain carbon is desirable so as not to increase the COD concentration of sewage. From this point of view, it is desirable to use inorganic acid salts such as iron chloride, iron sulfate, and iron nitrate instead of organic acid salt structures such as iron acetate and iron propionate.

Examples of the aluminum salt include polyaluminum chloride. Polyaluminum chloride is synthesized by adding hydrochloric acid to aluminum hydroxide. The structure is [Al ₂ (OH) _n Cl _6-n ] _m , where 1 ≦ n ≦ 5 and m ≦ 10.

  Examples of other salts include aluminum sulfate.

  In the case of rare earth metals such as neodymium and dysprosium, hydrochloride, sulfate, or nitrate is preferable because of its high solubility in water.

(Ii) polymers having acidic groups
A polymer having an acidic group may be a carboxyl group or a sulfonic acid group as the acidic group. Of these, polyacrylic acid is most preferable as a polymer having a carboxyl group because it is inexpensive and easily binds to a trivalent metal ion. In addition, polyaspartic acid and polyglutamic acid derived from amino acids are also characterized by low toxicity.

Alginic acid is one of the main components of seaweeds such as kombu, and has a feature of low environmental impact in that the raw material is derived from organisms.
Examples of the polymer having a sulfonic acid group include polyvinyl sulfonic acid and polystyrene sulfonic acid. Since these sulfonic acid groups have a higher acidity than carboxyl groups, the ratio of forming ionic bonds with metal ions is high, which is preferable in terms of obtaining stable aggregates.
A polymer having a carboxyl group is used more frequently in the world such as diapers and sanitary products, and is more preferable than a polymer having a sulfonic acid group because it is easily available and inexpensive.

  Moreover, when the water solubility of the polymer having an acidic group is low, solubility in water can be improved by making the acidic group into an ammonium salt structure, a sodium salt structure, or a potassium salt structure. After forming an ammonium salt structure, or a sodium salt structure or a potassium salt structure, an ionic bond can be efficiently formed with a trivalent metal ion by adding it to sewage.

  By the way, if the average molecular weight of the polymer having an acidic group is too low, the number of cross-linked sites of the aggregate is reduced, so that the stability of the aggregate is lowered. In addition, the agglomerates tend to become liquids with high viscosity. If it becomes like this, removal of an aggregate will become difficult by filtration. Therefore, the average molecular weight of the polymer having an acidic group is desirably 2,000 or more.

  In addition, when the temperature of sewage is 40 ° C. or higher, the aggregate becomes sticky when the average molecular weight is 2,000. In the case of oil sand drainage, the temperature may increase to about 60 ° C. In this case, the aggregate can be solidified even at a high temperature by further increasing the average molecular weight. Specifically, by setting the average molecular weight to 5,000 or more, the aggregate can be solidified even when the temperature of the sewage is 40 ° C. Therefore, the average molecular weight of the polymer having an acidic group is more preferably 5,000 or more. Further, by setting the average molecular weight to 10,000 or more, the aggregate can be solidified even when the temperature of the sewage is 60 ° C. Therefore, the average molecular weight of the polymer having an acidic group is more preferably 10,000 or more.

  On the other hand, if the molecular weight is too large, the solubility in water tends to decrease during the formation of crosslinks with trivalent metal ions and tend to precipitate. That is, there is a possibility that the organic acid and trivalent metal ions in the sewage are precipitated in the sewage before forming a cross-link by ionic bonds with all of the ionic bonds. If it becomes like this, a part of ionic bond state of an organic acid and a trivalent metal ion will remain in the state melt | dissolved in waste water. Therefore, the average molecular weight of the polymer having an acidic group is desirably 1,000,000 or less.

  In the present embodiment, the average molecular weight of the polymer indicates a number average molecular weight, and this value is measured by gel permeation chromatography.

(Iii) Additives for improving organic acid traps
When the acidity of the acidic group of the organic acid is low, the ratio of forming an ionic bond with the trivalent metal ion decreases. Therefore, by adding an inorganic salt such as sodium chloride or potassium chloride to the sewage before adding the polymer having an acidic group, the ratio of the organic acid ionically bound to the trivalent metal ion is increased. This is presumed that the allowable ratio of the organic acid that can be dissolved in the sewage is lowered due to an effect similar to salting out in which salt is added to precipitate the organic matter dissolved in the water.

  Inorganic salts to be added include alkali metals such as sodium chloride, potassium chloride, magnesium chloride and calcium chloride, and alkaline earth metal hydrochlorides, alkali metals such as sodium sulfate, potassium sulfate, magnesium sulfate and calcium sulfate, and alkaline earths Examples thereof include metal sulfates, alkali metals such as sodium nitrate, potassium nitrate, magnesium nitrate and calcium nitrate, and nitrates of alkaline earth metals.

  Moreover, the flocculant of this embodiment has a high performance for agglomerating and removing organic acids when the liquidity of wastewater is weakly acidic to neutral. In terms of pH, 5 to 7 is optimal. Although the organic acid can be removed even if the liquidity of the sewage does not fall within this range, it is necessary to reduce the removal rate or increase the proportion of the metal salt to be added.

  When metal salts such as iron chloride and aluminum sulfate are added, the liquidity tends to be acidic. Moreover, even if a water-soluble polymer having an acidic group is added, the pH of sewage tends to be acidic. Furthermore, the aggregate is stable as an insoluble substance in water at a pH of 2 to 5. If the aggregate is out of this range, the aggregate easily dissolves in water. Therefore, the pH of the sewage before adding the water-soluble polymer or metal salt having an acidic group is optimally 5-7.

(B) Aggregation method
(I) Outline of aggregation method
Hereinafter, the outline of the aggregation method will be described in (a) to (e). The method of making the organic acid into an aggregate is as shown in FIG. The acidic group is described as a carboxyl group in FIG. 2, but the same applies to a sulfonic acid group.
(A) Water-soluble polymer 6 having a carboxyl group is added to sewage containing organic acid 5.
(B) A form in which organic acid and a water-soluble polymer having a carboxyl group coexist in the sewage.
(C) Add iron salt 7.
(D) The iron ion and the carboxyl group of the organic acid and the carboxyl group of the water-soluble polymer are ionically bonded.
(E) Aggregates 8 that are insoluble in water are formed.

(Ii) Improvement measures for organic acid removal
A method for increasing the organic acid removal rate includes a method in which an inorganic salt is added to sewage before adding a polymer to be added later. As described above, it is estimated that the removal rate is increased by an effect similar to salting out. As the inorganic salt to be added, sodium chloride which is abundant in nature is suitable. Particularly in the case of sewage treatment in a subsea oil field, the average sodium chloride concentration in seawater is about 3%.

  The polymer is added after adding the inorganic salt. This is because even if an inorganic salt is added after the addition of the polymer, no further aggregation occurs.

  In addition, the organic acid removal rate can be improved by controlling the pH of the sewage before adding the water-soluble polymer or metal salt having an acidic group to 5 to 7 as described above.

(Iii) Larger aggregate
When adding a polymer solution having an acidic group as described in (ii) above, the organic acid can be efficiently trapped in the aggregate by stirring as vigorously as possible. However, if the stirring is too intense, the size of the agglomerates becomes too small and the clogging is likely to occur when passing through the filtration layer, so that the processing speed may be lowered.

  It was found that when suspended substances such as sand and oil droplets coexist in the sewage, they are taken into the aggregate during aggregation and the size of the aggregate is increased. Furthermore, it was also found that sand having a higher specific gravity is incorporated into the aggregates, so that the specific gravity is increased and sedimentation is likely to occur, which is suitable for removing the aggregates by filtration or the like.

(Iv) Removal of suspended substances
The flocculant of this embodiment is intended to remove organic acids in wastewater, but can also remove suspended substances as described above. Therefore, there is no need to perform aggregation using conventional polyaluminum chloride and polyacrylamide for removing suspended substances, so there is a merit that leads to a reduction in water purification process load (cost, processing time).

(V) Application of magnetic separation
When the aggregate is formed, the aggregate can be removed by magnetic separation by containing magnetic powder or iron powder in the aggregate.

  However, it is difficult to put magnetic powder or iron powder in the agglomerate after the metal salt is added, so add the metal powder to the sewage before adding the metal salt or together with the metal salt. It becomes possible to make it contain in an aggregate.

(2) Organic matter removal by heating sewage
As described above, the high molecular weight organic acid can be removed in the step using the flocculant, but the low molecular weight organic acid partially remains in water. Such an organic acid having a low molecular weight is generally highly volatile. Therefore, when such an organic substance is contained in water, it is possible to accelerate the volatilization process and remove the organic substance from the water by heating the water.

  In addition, this heating process may be a process before the process using the previous flocculant, or may be a subsequent process. However, the step of removing the organic substance using the flocculant and the step of removing the organic substance by heating water are different steps and are not performed simultaneously.

  The temperature of water during heating is preferably between 40 ° C and 100 ° C. In order to volatilize organic matter positively, the heating temperature is preferably higher than room temperature (40 ° C. or higher), and is preferably less than 100 ° C. in view of the boiling point of water. Furthermore, in oil sand drainage and the like, the drainage temperature itself may be about 60 ° C. Therefore, in order to positively remove low molecular weight organic matter from waste water discharged from the oil sand, 60 ° C. The above heating temperature is desirable.

  Next, the water purifier of this embodiment will be described. This is a device that specifically realizes the water treatment process described above.

1) Form 1 of water purifier
The basic structure of the water purifier of this embodiment is demonstrated using FIG.
Sewage is introduced into the first mixing tank 23 by the pump 21 through the pipe 22. The liquid in this is stirred by the overhead stirrer 24. Here, the liquidity of the sewage is confirmed. Although not shown in this figure, a pH sensor for confirming liquidity is provided in the first mixing tank.

  Here, when the pH of the sewage exceeds 7, the aqueous hydrochloric acid solution is introduced into the first mixing tank through the pipe 27 by the pump 26 from the aqueous hydrochloric acid tank 25. In addition, other inorganic acids such as sulfuric acid and nitric acid may be used instead of hydrochloric acid.

  Here, when the pH of the sewage is less than 5, an aqueous solution of sodium hydroxide is added instead of an aqueous solution of hydrochloric acid. In this way, liquidity is controlled. In place of sodium hydroxide, other alkali metal hydroxides such as potassium hydroxide may be used.

Next, an aqueous solution of a water-soluble polymer having an acidic group is introduced into a first mixing tank from a tank 28 of the aqueous solution of the water-soluble polymer having an acidic group by a pump 29 through a pipe 30.
After the aqueous solution of the water-soluble polymer having an acidic group is mixed with the sewage in the first mixing tank, the liquid in the first mixing tank is fed into the second mixing tank 33 through the pipe 32 using the pump 31. throw into. The liquid therein is stirred by an overhead stirrer 34.

Next, the aqueous solution of the trivalent metal salt is introduced into the second mixing tank from the tank 35 of the aqueous solution of the trivalent metal salt through the pipe 37 by the pump 36.
When an aqueous solution of a trivalent metal salt is added, aggregates are generated in the second mixing tank. The liquid in which the aggregates are mixed flows into the filtration unit 39 by opening the valve 38. The liquid that has flowed in is filtered through a filtration layer 40 made of sand for filtration, and then filtered again by a porous member 41 and comes out as water with reduced organic acid.

  FIG. 5 shows an apparatus having two sets of filtration units. First, the filtration process is performed in the left filtration unit, and when the filtration layer is clogged and the filtration rate is reduced, the filtration process is performed in the right filtration unit. By performing a treatment such as exchanging the filtration layer of the left filtration unit during the filtration process on the right side, it is possible to prevent the filtration process from being delayed as much as possible.

  The tip 42 of the pipe 37 where the liquid is introduced into the second mixing tank is not straight, but is spread out like a fan or a shower mouth so that the liquid is introduced into the second mixing tank as widely as possible. It is preferable to make it. This is because agglomeration starts instantaneously with the addition, and when the solution is introduced into a small area, the introduced liquid is included in the agglomerates and cannot be utilized for further agglomerate generation.

  The tip of the pipe 32 and the part of the pipe 37 where the liquid is poured into the second mixing tank is provided on the liquid level so as not to contact the liquid level of the second mixing tank. This is because aggregates generated in the second mixing tank may adhere to the tip of a pipe or the like and block the hole at the tip.

Further, the liquid from the filtration unit 39 is put into the heating tank 91. The heating tank is heated using a heater 92 or the like so as to reach a predetermined temperature between 40 ° C. and 100 ° C. The liquid in the heating tank is stirred by an overhead stirrer 93.
By taking out the heat-treated water, purified water from which low molecular weight to high molecular weight organic substances are removed can be obtained.

  In addition, in the apparatus shown here, although the bathtub which stores the water called a heating tank is used, about a heating process part, a pipeline may be sufficient. By using a pipeline, it is not necessary to store water, and space saving of the apparatus can be expected. Moreover, compared with heating a large amount of bathtubs, by adjusting the diameter of the pipeline and the like, heating becomes easier, which can contribute to energy saving.

2) Form 2 of water purifier
The basic structure of what has a sedimentation tank among the water purifiers of this embodiment is demonstrated using FIG.
The configuration of this apparatus has a sedimentation tank 43 instead of the filtration unit. With this configuration, agglomerates are precipitated in the lower part of the sedimentation tank, and the supernatant liquid is put into the next heating tank 91, and purified water from which high molecular weight organic substances have been removed from low molecular weight can be obtained by the same treatment as in the first embodiment. .

3) Form 3 of water purification equipment
The basic structure of what has the mechanism which prevents the clogging of a filtration layer in a filtration part among the water purifiers of this embodiment is demonstrated using FIG.

  As the filtration process continues, the surface of the filtration layer 40 is clogged with aggregates, and the filtration rate decreases. Therefore, in the apparatus of FIG. 5, a disk 44 having an uneven surface is disposed near the upper surface of the filtration layer, and a filtration layer stirring mechanism 45 that rotates the disk 44 with a motor is provided. As a result, the upper surface of the filtration layer is scraped to eliminate clogging caused by aggregates, thereby enabling smooth filtration. The liquid obtained here is put into the next heating tank 91, and purified water from which high molecular weight organic substances have been removed from low molecular weight can be obtained by the same treatment as in the first embodiment.

4) Form 4 of water purifier
A basic configuration of the water purifier using the magnetic separation method will be described with reference to FIG.
The sewage is introduced into the first mixing tank 53 by the pump 51 through the pipe 52. The liquid in this is stirred by the overhead stirrer 54. Here, the liquidity of the sewage is confirmed. Although not shown in this figure, a pH sensor for confirming liquidity is provided in the first mixing tank.

  Here, when the pH of the sewage exceeds 7, the aqueous hydrochloric acid solution is introduced into the first mixing tank through the pipe 57 from the aqueous hydrochloric acid tank 55 by the pump 56. When the pH of the sewage is less than 5, an aqueous solution of sodium hydroxide is added instead of an aqueous solution of hydrochloric acid. In this way, liquidity is controlled.

  Next, an aqueous solution of the water-soluble polymer having acidic groups is introduced into the first mixing tank from the tank 58 of the aqueous solution of water-soluble polymer having acidic groups through the pipe 60 by the pump 59.

  After the aqueous solution of the water-soluble polymer having an acidic group is mixed with the sewage in the first mixing tank, the liquid in the first mixing tank is fed to the second mixing tank 63 through the pipe 62 using the pump 61. throw into. The liquid therein is stirred by an overhead stirrer 64.

  Next, the second aqueous polymer solution is introduced into the second mixing tank from the trivalent metal salt aqueous solution tank 65 through the pipe 67 by the pump 66. When an aqueous metal salt solution is added, aggregates are formed in the second mixing tank.

  By the way, an overhead stirrer 68 (blades and the like in the tank are not shown) for mixing the metal salt aqueous solution and the magnetic powder such as iron powder is provided in the metal salt aqueous solution tank. Although the aqueous solution of metal salt and magnetic powder can be put separately in the second mixing tank, there is a tendency that the density per unit deposition of magnetic powder contained in the aggregate tends to be uneven. As described above, it is desirable to add the mixture into the second mixing tank after mixing in advance. Or the same effect is acquired even if it mixes with a 1st mixing tank beforehand.

  The produced agglomerates are in a state where magnetic powder is mixed. The agglomerates adhere to the drum 69 having a mesh-like surface and magnetism. The drum rotates clockwise in this figure, and agglomerates adhering to the surface are peeled off from the drum mesh by the scraper 70. The peeled agglomerates are collected in an agglomerate accumulation container 71 having a meshed bottom surface. Since the agglomerate just collected contains a considerable amount of water, it is drained from the mesh on the lower surface of the agglomerate accumulation container.

On the other hand, the water passing through the mesh of the drum is in a state in which aggregates are removed by the mesh. This water exits through pipe 72 in the center of the drum as reduced water.
The liquid obtained here is put into the next heating tank 91, and purified water from which high molecular weight organic substances have been removed from low molecular weight can be obtained by the same treatment as in the first embodiment.

  The tip 73 of the pipe 67 where the liquid is poured into the second mixing tank is not straight, but is spread out like a fan or a shower mouth so that the liquid is poured into the second mixing tank as widely as possible. It is preferable to make it. This is because agglomeration starts instantaneously with the addition, and when the solution is introduced into a small area, the introduced liquid is included in the agglomerates and cannot be utilized for further agglomerate generation.

  The tip of the portion of the pipe 62 and the pipe 67 where the liquid is poured into the second mixing tank is provided on the liquid level so that the tip of the part does not contact the liquid level of the second mixing tank. This is because aggregates generated in the second mixing tank may adhere to the tip of a pipe or the like and block the hole at the tip.

  In this apparatus, a drum for magnetic separation may not be provided, and a mechanism for filtering the aggregate after settling may be provided. Since the aggregate contains the magnetic powder, the specific gravity increases and it tends to sink. Therefore, most of the agglomerates are submerged under the second mixing tank, and the supernatant is filtered, whereby water can be purified without magnetic separation.

5) Form 5 of the water purifier
A basic configuration of the water purification apparatus according to the present embodiment, which includes two drums using a magnetic separation method, will be described with reference to FIG.
This apparatus collects agglomerates on a drum 69 having a mesh surface, and then blows out a small amount of water from the inside of the drum, thereby peeling the agglomerates from the mesh of the drum and flying it toward the drum 74. Adhere to. The surface of this drum is not a mesh but a metal plate.

  When peeling off the agglomerates, the surface of the mesh is rubbed with a scraper. At this time, the scraper may be caught on the mesh and the mesh may be damaged.

  However, in the present apparatus, when the aggregate is peeled off by the scraper, the metal plate that is stronger than the mesh is in contact with the scraper.

6) Form 6 of water purifier
A basic configuration of the water purification apparatus according to this embodiment in which the agglomerate removal tank 75 is separately provided by a magnetic separation method will be described with reference to FIG.
In this method, the agglomerates formed in the second mixing tank are not magnetically separated in the same tank, but are transferred to another tank (aggregate removal tank) where magnetic separation is performed. The amount of treated water put into the aggregate removal tank is controlled by a valve 76.

  By adopting this configuration, a considerable proportion of aggregates remain in the second mixing tank before magnetic separation, and the amount of aggregates to be removed by magnetic separation is reduced. Therefore, the drum mesh is less likely to be clogged, and maintenance on the mesh can be reduced, which is preferable.

7) Form 7 of water purifier
A basic configuration of the water purification apparatus according to the present embodiment, in which one drum is provided by the magnetic separation method and the aggregate removal tank 77 is separately provided, will be described with reference to FIG.
This reduces the distance between the bottom of the agglomerate removal tank and the drum so that the agglomerates adhere to the drum almost completely. In this way, purification is performed with one drum. Aggregates adhering to the drum are removed with a scraper. This method is suitable because it can be cleaned with a single drum, and therefore, the agglomerate removal tank, and thus the space of the apparatus can be saved.

8) Form 8 of water purifier
In the water purification apparatus shown above, the heating tank is an apparatus that is disposed after the step of using the flocculant. However, a heating tank may be arrange | positioned before the process using a flocculant, and the basic composition is demonstrated using FIG. In addition, the structure which arrange | positions a heating tank before the process using a coagulant | flocculant is applicable similarly also to the apparatus shown to the form 2 to form 7 above.

  The sewage is introduced into the heating tank 91 by the pump 94 through the pipe 95. The liquid therein is stirred by an overhead stirrer 93. The heat-treated water is further fed into the first mixing tank 23 by the pump 21 through the pipe 22. The liquid in this is stirred by the overhead stirrer 24. Here, the liquidity of the sewage is confirmed. Although not shown in this figure, a pH sensor for confirming liquidity is provided in the first mixing tank.

  Here, when the pH of the sewage exceeds 7, the aqueous hydrochloric acid solution is introduced into the first mixing tank through the pipe 27 by the pump 26 from the aqueous hydrochloric acid tank 25. In addition, other inorganic acids such as sulfuric acid and nitric acid may be used instead of hydrochloric acid.

  Next, an aqueous solution of a water-soluble polymer having an acidic group is introduced into a first mixing tank from a tank 28 of the aqueous solution of the water-soluble polymer having an acidic group by a pump 29 through a pipe 30.

  After the aqueous solution of the water-soluble polymer having an acidic group is mixed with the sewage in the first mixing tank, the liquid in the first mixing tank is fed into the second mixing tank 33 through the pipe 32 using the pump 31. throw into. The liquid therein is stirred by an overhead stirrer 34.

  Next, the aqueous solution of the trivalent metal salt is introduced into the second mixing tank from the tank 35 of the aqueous solution of the trivalent metal salt through the pipe 37 by the pump 36.

  When an aqueous solution of a trivalent metal salt is added, aggregates are generated in the second mixing tank. The liquid in which the aggregates are mixed flows into the filtration unit 39 by opening the valve 38. The liquid that has flowed in is filtered through a filtration layer 40 made of sand for filtration, and then filtered again by a porous member 41 and comes out as water with reduced organic acid.

9) Form 9 of water purifier
In the water purification apparatus shown above, the low molecular weight organic substance recovered by the heating process is reused as a fuel to be used as a heat source for the heating process. The process of organic substance recovery and heat source utilization will be described with reference to FIG.

  The low molecular weight organic substance 101 that volatilizes in the heating process is collected from the pipe 102, and cooled (cooling equipment 103) in the collection process is stored in the storage 104. The stored organic matter is burned and the heat generated here is used as a heat source for the heating tank. Thereby, resources can be reused and a low-cost water purifier can be obtained.

10) Form 10 of water purifier
The basic configuration of the oil recovery and water purification system of this embodiment will be described with reference to FIG.
In the oil extraction plant 81, steam is blown into the oil sand to separate the oil from the sand. When steam is blown in, the oil is heated and the clay is lowered and separated from sand as oily water mixed with steam-derived hot water. Since the oily water is allowed to stand and is separated into oil and moisture due to the difference in specific gravity, the oil extraction is completed by collecting the upper oil (commonly called bitumen). The extracted oil is separated into gasoline, heavy oil, asphalt, etc. depending on the boiling point in the oil production process, and used in various industries.

  By the way, the mixed sewage discharged from the oil extraction plant is sent to the water purifier 83 through the pipe 82. Here, the treated water purified by removing oil, organic acid, and the like is sent to the steam generator 85 through the pipe 84. The treated water is heated by this apparatus to become steam, and is sent to the oil extraction plant through the pipe 86. This water vapor is used again in the process of extracting oil from the oil sand.

  In the process of heating the treated water in order to produce steam with the steam generator, the aggregate is transported from the water purifier by the belt conveyor 87. The aggregate contains an oil, an organic acid, and a water-soluble polymer having an acidic group, and has an effect of reducing waste by burning it as part of the fuel in the process of heating the treated water.

  An example of this embodiment is shown below. In addition, this invention is not restrict | limited to these Examples.

  Prepare 1 liter of test water (1 mmol as naphthenic acid) in which 220 ppm of naphthenic acid is dissolved as an organic acid. This water will be referred to as “simulated sewage” in the future. The pH of this simulated sewage was 6.9.

  By the way, naphthenic acid is a general term for carboxylic acids of cyclic hydrocarbons, and the molecular weight varies depending on the size of the ring and the presence or absence of branched alkyl chains. In the experiment of this embodiment, these mixtures were obtained and used after measuring the average molecular weight. According to the measurement, the average molecular weight was 220. Further, in order to dissolve naphthenic acid in water, naphthenic acid was added in advance in an ammonium salt structure.

  While stirring the simulated sewage, 1.44 g of a 5% by weight aqueous solution of polyacrylic acid having a carboxyl group as a polymer having an acidic group (average molecular weight is 250,000) (the number of carboxyl groups that are acidic groups is 1 mmol) Add

  When 1.62 g of a 10% by weight aqueous solution of iron (III) chloride (1 mmol as the number of iron ions) is added as a trivalent metal salt, aggregates are precipitated. The aggregate was collected by filtration, and the filtrate was further heated to 95 ° C. to obtain purified water. When this purified water was quantified by GC, the naphthenic acid concentration decreased to 1 ppm or less. As a result of analyzing the water before heating, the naphthenic acid concentration was 10 ppm.

  It was confirmed that naphthenic acid dissolved in water (from low molecular weight naphthenic acid to high molecular weight naphthenic acid) can be removed by the process of this embodiment.

  In this embodiment, the water treatment amount is as small as 1 liter, but the same treatment is possible even with a large amount of water, and the same effect can be expected.

  The same operation as in Example 1 was performed using 2 g of a 10 wt% aqueous iron sulfate solution (1 mmol as the number of iron ions) instead of the 10 wt% aqueous solution of iron (III) chloride. When purified water was quantified by GC analysis, the naphthenic acid concentration decreased to 1 ppm or less.

  The same operation as in Example 1 was carried out using 1.06 g of a 10 wt% polyaluminum chloride aqueous solution (1 mmol as the number of aluminum ions) instead of the 10 wt% aqueous solution of iron (III) chloride. When purified water was quantified by GC analysis, the naphthenic acid concentration decreased to 1 ppm or less.

  The same operation as in Example 1 was performed using 1.71 g of a 10 wt% aqueous solution of aluminum sulfate (1 mmol as the number of aluminum ions) instead of the 10 wt% aqueous solution of iron (III) chloride. When purified water was quantified by GC analysis, the naphthenic acid concentration decreased to 1 ppm or less.

  As described above, in Examples 2 to 4, it was shown that naphthenic acid can be removed by using a trivalent metal hydrochloride such as iron or aluminum, or a metal salt such as sulfate.

  The same operation as in Example 1 was carried out using 1.72 g of a 5 wt% aqueous solution of polymethacrylic acid (1 mmol as the number of carboxyl groups which are acidic groups) instead of 1.44 g of a 5 wt% aqueous solution of polyacrylic acid. Went. When purified water was quantified by GC analysis, the naphthenic acid concentration decreased to 1 ppm or less.

  The same operation as in Example 1 was performed using 1.84 g of a 10 wt% aqueous solution of polystyrene sulfonic acid (1 mmol as the number of sulfonic acid groups) instead of 1.44 g of a 5 wt% aqueous solution of polyacrylic acid. . When purified water was quantified by GC analysis, the naphthenic acid concentration decreased to 5 ppm or less.

  It was confirmed that even when a water-soluble polymer having a sulfonic acid group or the like is used as the polymer having an acidic group, the organic acid dissolved in water can be removed.

  In Example 1, 100 mg of ferrite-based magnetic powder was added to an aqueous solution of iron chloride, and then added to simulated sewage. After the agglomerates were generated, a permanent magnet was placed in the simulated sewage and pulled up 30 seconds later. About 90% of the agglomerates adhered to the magnet surface. The rest was stuck to the surface of the container containing the test water.

  The concentration of naphthenic acid in the simulated wastewater excluding the aggregates was 10 ppm. Further, purified water was obtained by heating the water to 95 ° C. When the purified water was quantified by GC analysis, the naphthenic acid concentration was 1 ppm or less.

  From the above, it was confirmed that the organic acid can be removed from the test water by using magnetic powder and a magnet without performing filtration.

  Similar results were obtained even when the magnetic powder was mixed with the aqueous solution of the polymer having an acidic group before adding the aqueous solution of iron chloride.

DESCRIPTION OF SYMBOLS 1 Micro floc 2 Contaminated fine particle 3 Floc 4 Magnetic powder 5 Organic acid 6 Water-soluble polymer 7 which has a carboxyl group 7 Iron salt 8 Aggregate 21, 26, 29, 31, 36, 51, 56, 59, 61, 66, 94 Pump 22, 27, 30, 32, 37, 52, 57, 60, 62, 67, 72, 82, 84, 86, 95 Piping 23, 53 First mixing tank 24, 34, 54, 64, 68, 93 Overhead stirrer 25, 55 Hydrochloric acid aqueous solution tanks 28, 58 Water-soluble polymer aqueous solution tanks 33, 63 with acid groups Second mixing tank 35 Trivalent metal salt aqueous solution tanks 38, 76 Valve 39 Filtration Part 40 Filtration layer 41 Porous members 42 and 73 The tip 43 of the portion where the liquid is poured into the second mixing tank 43 The sedimentation tank 44 The disk 45 with irregularities on the surface The filtration layer stirring mechanism 65 The metal salt Aqueous tanks 69, 74 Drum 70 Scraper 71 Aggregate collection container 75, 77 Aggregate removal tank 81 Oil extraction plant 83 Water purification device 85 Water vapor generation device 87 Belt conveyor 91 Heating tank 92 Heater

Claims (11)

A process of aggregating organic matter in wastewater using a flocculant;
And a step of heating the waste water.   The water treatment process according to claim 1, further comprising a step of recovering the organic matter volatilized in the step of heating the wastewater after the step of heating the wastewater.   The water treatment process according to claim 2, wherein the recovered organic matter is used as a fuel in a step of heating the sewage.   The water treatment process according to claim 1, wherein the flocculant contains a polymer having an acidic group and a trivalent metal salt.   The water treatment process according to claim 4, wherein the polymer having an acidic group is a carboxyl group.   The water treatment process according to claim 1, wherein the step of heating the sewage is performed at 40 ° C. or more and 100 ° C. or less.   2. The water treatment process according to claim 1, wherein the step of heating the wastewater is performed at 60 ° C. or more and 100 ° C. or less.   The water treatment process according to claim 1, wherein the step of aggregating the organic matter includes a step of adding magnetic powder. A mechanism for adding a flocculant to wastewater containing organic matter;
And a mechanism for heating the sewage.   The water purifier according to claim 9, wherein the flocculant contains a polymer having an acidic group and a trivalent metal salt.   The water purifier according to claim 9, further comprising a mechanism for adding magnetic powder.