JPH11197405A - Treatment method for used emulsion type aqueous water-soluble coolant liquid and waste liquid treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste liquid treatment apparatus capable of treating a used emulsion type water-soluble coolant liquid while keeping stability and causing no corrosion in good work environments and carrying out chemical treatment and pressurizing flotation treatment by a single apparatus. SOLUTION: A flotation separation tank 1 comprising a scraper 2 for discharging flocs in an upper part, a supply aperture 20 for supplying a chemical agent, a used liquid, air, etc., in a lower part, and a discharge route 22 for discharging a treated liquid is installed. A measurement tank 16 communicated with the flotation separation tank in a lower part, enabled to receive a used liquid, and comprising measuring apparatuses 14, 15 is also installed. Further, a buffer tank 17 for storing the excess used liquid from the measurement tank and a circulation route 25 for sending the used liquid in the buffer tank to the flotation separation tank are installed. An electrolytic material 8 or acid 9 containing divalent cation is added to the used liquid, the pH is controlled to be 5-5.5, and while keeping the pH at 5-5.5, an inorganic flocculant 11 is successively supplied by a pump and then pressurized air is supplied to carry out flotation separation of flocs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating an emulsified water-soluble coolant waste liquid used for cutting and grinding.

[0002]

2. Description of the Related Art This kind of waste liquid contains a large amount of an oil, an emulsifier for emulsifying and dispersing the oil, an organic acid and ethanolamine, and the TOC, BOD and COD can reach tens of thousands of mg / lit. Conventionally, this kind of waste liquid is added with mineral acid (sulfuric acid, nitric acid, hydrochloric acid, etc.) to adjust the pH to 1 to 3, break emulsion, and separate oil by flotation, and then combine coagulation sedimentation treatment, microbial treatment, filtration, activated carbon treatment, etc. The water quality is such that it can be released. Further, JP-A-63-256106 discloses a method of adjusting the waste liquid to pH 4, adding a sulfuric acid band, magnesium oxide, and slaked lime, adding a polymer flocculant, enlarging the floc, and removing the floc. Has been disclosed. In Japanese Patent Publication No. 17433/1990, wastewater is p
A method has been adopted in which H3 to H5 is used to oxidize with hydrogen peroxide and ferrous sulfate, and the oxidized water is subjected to coagulation and sedimentation at pH 6 to 8, and solid-liquid separated.

[0003]

However, according to the above-mentioned processing method, in the first stage processing for emulsion destruction, pH 1 to 3, or pH 4 or pH 4
An acid treatment on the strongly acidic side such as 3 to 5 is required, and in such a pH range, corrosion of the treatment apparatus is caused,
There is a problem that it is not preferable in the working environment. In addition, in the conventional method, after the emulsion is broken, a neutralization treatment is performed when performing the coagulation treatment, but at this time, since a part of the broken emulsion is re-emulsified, the stability of the treatment is lacking,
It may cause a fatal failure in subsequent processing.

[0004] On the other hand, as an example for promoting floc of the treated waste liquid, air is dissolved in pressurized waste water, and fine air bubbles are attached to suspended matter and sludge in the waste water to increase the floating capacity. A pressure flotation method for separating and removing flocs is known (for example, “Pollution Prevention Equipment” No. 51)
-53 (published March 28, 1995, published by the Industrial Research Institute Encyclopedia Publishing Center, editorial committee of new environmental management equipment encyclopedia), "Water Recycling (Basic)", pp. 103-108 (published 1992) Published on September 20, 2000 by Jinjinshokan Co., Ltd., supervised by the Japan Institute of Engineers,
Author Youroku Wada). However, since the above treatment is a strong acid, similar to the above, acid treatment before pressure flotation treatment,
There is a problem that a pressurized flotation tank suitable for a strong acid is required and equipment cost is increased. Further, there is a problem that the size of the apparatus is increased because the chemical treatment and the pressure levitation treatment are performed separately.

In view of the above problems, it is an object of the present invention to provide a method for treating an emulsion-type water-soluble coolant waste liquid, which ensures the stability of treatment, prevents troubles due to corrosion, and improves the working environment. It is another object of the present invention to provide an efficient waste liquid treatment apparatus as a whole system by performing the chemical treatment and the pressure flotation treatment with the same apparatus to downsize the apparatus.

[0006]

According to the present invention, an emulsion containing a divalent cation, such as magnesium sulfate heptahydrate, is added to a water-soluble emulsion waste liquid to destabilize the emulsified oil. After that, the pH is adjusted to 5 to 5.5 by adding an acid such as sulfuric acid and the emulsion is completely destroyed, and the pH is maintained at 5 to 5.5 by adding an acid or using an alkali such as caustic soda. The above-mentioned problem has been solved by adding an inorganic flocculant such as polyaluminum chloride to provide a method for treating an emulsion-based water-soluble coolant waste liquid which enlarges flocculated floc and facilitates separation and removal.

[0007] An electrolyte having a divalent cation such as magnesium sulfate heptahydrate may be added in any form, but it is desirable to add it in the form of an aqueous solution by utilizing its high solubility. A high effect can be obtained by adding 0.3% by weight or more, preferably about 0.5% by weight.

[0008] The pH of the acid treatment is preferably as low as possible in order to destroy the emulsion of the water-soluble coolant, but should be selected as low as possible without interfering with the coagulation ability of the subsequent polyaluminum chloride. , PH 5 to 5.5 is desirable.

The addition of an inorganic coagulant such as polyaluminum chloride is at least 0.4% by weight, preferably about 0.5% by weight, whereby a coagulation effect can be obtained.

[0010] Since the waste liquid treated by such a method has a low acidity of pH 5 to 5.5, floc is floated and separated by a pressure flotation method using a conventional pressure flotation device, so that floc is more easily flocculated. Floc can be separated and removed, and primary treated water with stable water quality can be obtained.

(Action) The action of the method for treating an emulsion-based water-soluble coolant waste liquid according to any one of claims 1 to 5 will be described in detail. An electrolyte having a divalent cation such as magnesium sulfate added to the waste liquid is easily soluble in water.
Therefore, the coagulation action of the divalent cation of magnesium is efficiently performed, and the emulsion is easily destabilized. Subsequently, the emulsion is broken by adding acid. Further, an acid or an alkali is added and pH 5
By adding an inorganic coagulant such as polyaluminum chloride while maintaining the value at 5.5, flocs can be efficiently coagulated while maintaining the state in which the emulsion is broken.

Emulsion-based water-soluble coolant has a pH
Is less than 5.5, the state rapidly becomes unstable. Also, the coagulation effect of inorganic coagulant such as polyaluminum chloride can be maintained
Since the pH is in the range of 5 to 8, the pH of the treatment liquid is 5 to 5.5.
In this case, the effect of the acid treatment and the coagulation effect of the inorganic coagulant are sufficiently exhibited. In the present invention, the above-described three-stage treatment exerts a synergistic effect, and can efficiently treat an emulsion-based aqueous solution coolant wastewater at a pH of 5 or more.

In such a method for treating the waste water of an emulsion-based water-soluble coolant, each treatment is performed in a separate tank, and furthermore, since the acidity is low, it is possible to carry out the treatment using a general treatment apparatus by a pressure flotation method. is there. However, it is reasonable to carry out each chemical treatment and physical treatment such as pressurized levitation in one treatment tank.

According to a sixth aspect of the present invention, a scraper for discharging flocs is provided at an upper portion, a supply port for supplying chemicals, waste liquid, air, etc. is provided at a lower portion, and a discharge passage for discharging treated waste liquid. A flotation tank having a measuring tank provided with a measuring instrument which is in communication with the flotation tank at a lower portion and capable of supplying waste liquid, a buffer tank for storing excess waste liquid from the measuring tank, By providing a waste liquid treatment apparatus provided with a circulation path for sending the waste liquid in the buffer tank to the flotation tank, chemical treatment and physical treatment such as pressurized flotation can be performed in a batch process in one treatment tank. I made it.

With this configuration, the waste liquid to be treated is supplied from the measurement tank to the flotation tank, and when it reaches a predetermined amount,
Excess waste liquid in the measurement tank is stored in the buffer tank by means such as overflow. Since the measurement tank communicates with the flotation tank at the lower part, the processing liquid, pH value, and the like can be measured without being affected by flocks or the like. When the amount of waste liquid to be treated reaches a predetermined amount, supply is stopped, and while the waste liquid to be treated is sent from the buffer tank to the flotation tank, chemicals are sequentially charged, chemical treatment is performed, and pressurized air is sent to pressurize. To surface. The floating flocs are discharged out of the tank by the scraper at the top. The waste liquid to be treated circulates through the flotation tank, measurement tank, and buffer tank.
This circulation makes the state of the waste liquid in each tank uniform,
The measurement error between the measurement tank and the flotation tank is small. After the predetermined processing is completed, the processed waste liquid is discharged from the discharge path and sent to the subsequent process.

The processing waste liquid is always circulated through the buffer tank, the floating separation tank and the measuring tank in order to keep the state of the waste liquid in the flotation tank constant, so that it is advisable to mix chemicals, pressurized air and the like at the same time. Therefore, in claim 7,
The supply port is used as the outlet of the circulation path, and a plurality of types of chemicals, waste liquid, and pressurized air can be supplied singly or as a mixture to be supplied into the treatment tank, thereby simplifying the structure.

In particular, in the treatment method of the present invention, physical treatment may be performed by a general pressure flotation apparatus after the chemical treatment. However, since the waste liquid is treated at a pH of 5 to 5.5, measures against corrosion and the like can be taken. It is simple and, by using the waste liquid device of the present invention, the chemicals are sequentially injected while circulating the buffer tank, flotation tank, and measurement tank, and the flotation is also performed under pressure, so that the waste liquid is small and stable. Can be processed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with respect to a method for treating an emulsion-based water-soluble coolant waste liquid of the present invention using the waste liquid treatment apparatus of the present invention.
FIG. 1 is an explanatory view of a waste liquid treatment apparatus of the present invention. The present waste liquid processing apparatus is a batch (batch) type processing apparatus. In FIG. 1, the floc floating on the processing waste liquid is placed on the upper part in FIG.
A scraper 2 for discharging to a flock discharge port 3 while rotating by means of a supply port 20 for supplying chemicals, waste liquid, air, etc. at a lower portion, and a discharge path for discharging treated waste liquid to a next step by a pump 18. 22, a flotation tank 1 provided with a drain 19 for discharging the residue at the bottom. A measurement tank 16 communicated with the flotation tank 1 through a lower communication passage 23 is also provided. The measuring tank 16 has a level sensor 15 for detecting a water level of the measuring tank and a p for detecting a pH value.
An H electrode 14 is provided.

The buffer tank 1 is located adjacent to the measuring tank.
7 is provided so that excess waste liquid in the measurement tank overflows from the partition 24 and flows into the buffer tank. The waste liquid from the buffer tank 17 is sent to the flotation tank 1 from the pressurized tank 6, the line mixer 12, the pressure reducing valve 13, and the supply port 20 by the pressurized pump 4, thereby forming a circulation path 25. An air flow meter 5 is provided with the pressurizing pump, and pressurized air is supplied to a circulation path 25.
It can be supplied within. Reference numeral 7 denotes a pressure gauge for measuring a line pressure. The pressure reducing valve 13 is for adjusting the pressure and the flow rate of the circulating fluid.

Between the pressurized tank 6 and the line mixer 12, a magnesium sulfate pump 8 for injecting magnesium sulfate, a sulfuric acid pump 9 for injecting sulfuric acid, a caustic soda pump 10 for injecting caustic soda, and a polychloride for injecting polyaluminum chloride. Aluminum pumps 11 are provided so that they can be independently injected.

In the present invention, the waste aqueous solution coolant of the emulsion system is treated by the waste liquid treatment tank as follows. Raw water is sucked from a raw water tank (not shown) by a water pump (not shown) and passed through an oil / water separation tank (not shown). The pressurized flotation tank 1 and the measuring tank 16 are connected to a lower communication passage 23.
The waste liquid is stored in the measurement tank and the pressurized flotation tank, and the excess waste liquid overflows from the partition 24 and flows into the buffer tank 17 to be supplied to the buffer tank 17 when the predetermined amount is reached.

Next, while the waste liquid is circulated from the buffer tank 17 through the circulation path 25 by the pressure pump 4, a predetermined amount of an aqueous solution of magnesium sulfate is first added by the pump 8, and the pressure Return to After circulating for a predetermined time, after the reaction is completed, sulfuric acid is added by the pump 9 to adjust the pH to 5-5.5, and the emulsion is completely destroyed. Then, after adding a predetermined amount of polyaluminum chloride by the pump 11, the pump 1
Using 0, the pH is adjusted to 5 to 5.5 by adding caustic soda to flocculate and enlarge the floc.

Further, while circulating the waste liquid, while injecting a predetermined amount of air from the air flow meter 5 into the pressurizing pump 4,
The microbubbles are mixed and dissolved in the waste liquid, made uniform in the pressurized tank 6, and then flow into the pressurized floating tank 1. The pressure of the air dissolved in the waste liquid is released in the flotation tank, and the air becomes fine bubbles again and adheres to the flocs to float. In this way,
While circulating the treatment waste liquid between the flotation tank 1, the measuring tank 16 and the buffer tank 17, the rotary scraping machine 2
The floating floe is scraped off and discharged from the floc discharge port 3. After the above operation is performed for a predetermined time, the intermediate layer of the floating separation tank is discharged to the next step (not shown) using the pump 18.

Since the measuring tank 16 is provided outside the floatation / separation tank 1, the floating flocs hardly flow into the measuring tank, and no malfunction occurs due to the adhesion of the flocs to the pH electrode 14 and the level sensor 15. . The excess waste liquid overflowing from the measuring tank 16 flows into the buffer tank 17 and is circulated by the pressurizing pump 4, and this buffer tank plays a role in maintaining the water level of the flotation tank 1. The floc is scraped off by the flotation tank, and even if some water is taken out at the same time, the water level of the flotation tank separation is kept constant by the buffer tank, so the scraping operation of the floated flock is stable and can be efficiently achieved. . Needless to say, the waste liquid treatment apparatus of the present invention can be applied not only to the method for treating the emulsion-based water-soluble coolant waste liquid of the present invention but also to various treatment methods including conventional ones.

[0025]

Next, an embodiment of a method for treating an emulsion-based water-soluble coolant waste liquid of the present invention will be described.

Example 1 An experiment was conducted on the effect of the added amounts of magnesium sulfate heptahydrate and polyaluminum chloride. The processing tests of Experiments 1 to 7 were carried out using microemulsion type water-soluble coolant waste liquid corresponding to JIS W2. One lit of a waste liquid of a microemulsion type water-soluble coolant corresponding to JIS W2 was taken in a beaker, a predetermined amount of magnesium sulfate heptahydrate was added, and the mixture was stirred for 15 minutes. Next, after stirring for 5 minutes while adjusting the pH to 5 with sulfuric acid, a predetermined amount of polyaluminum chloride was added. P lowered by adding polyaluminum chloride
The mixture was stirred for 3 minutes while adjusting H to 5.0 to 5.1. After stopping the stirring, the floc was allowed to stand for 1 hour to float the floc, and the TOC (total organic carbon content) of the lower layer was measured. The results are shown in Table 1.

[0027]

[Table 1]

As shown in Table 1, by adding at least 0.3% by weight of magnesium sulfate heptahydrate and at least 0.4% by weight of polyaluminum chloride, desirably, at least 0.5% by weight of both agents is added. It is understood that the properties and the clarity after the treatment are good. Although not described in Table 1, only the sulfuric acid was added to the same waste liquid to adjust the pH to 3, and the TOC of the liquid filtered through a ceramic filter was 9000 mg / lit. From 8700 to 89 in 3
It was found that the dose was 00 mg / lit, and the same or better results could be obtained.

(Example 2) Next, treatment tests of Experiments 8 to 11 were carried out on the influence of pH. For the same waste liquid as in Example 1, the addition amounts of magnesium sulfate heptahydrate and polyaluminum chloride were each fixed at 0.5% by weight, and the pH at the time of treatment was changed from 4.5 to 6.5. A processing test was performed in the same procedure as in Example 1. After the treatment, the TOC of the lower layer clarified liquid was measured. The results are shown in Table 2.

[0030]

[Table 2]

As shown in Table 2, when the pH is 6 or more, the flocculence of the generated floc and the clarity of the treatment liquid are very good in the treatment at pH 5 or more, but the TOC of the treatment liquid is 100 or more.
When the pH was about 00 mg / lit and the pH was 4.5 or less, a cohesive property was poor and a clear treatment liquid could not be obtained. On the other hand, in the pH range of 5 to 5.5, the acid treatment effect and the coagulation effect of polyaluminum chloride are exhibited, and a synergistic effect is exhibited. As a result, only a clear treatment liquid having good coagulation property can be obtained. In addition, the TOC of the processing solution can be reduced to about 45% of the raw water, and the load on the next process can be reduced. For example, when the next step is performed by biological treatment or the like, the biological inhibitory component can be efficiently removed. The remaining TOC component is easily dissolved in water, and is considered to be due to ethanolamine which cannot be removed by the coagulation treatment.

(Example 3) Next, the same experiment as in Example 1 was conducted for an emulsion type water-soluble coolant waste liquid corresponding to JIS W1. Example 3 (Experiment 1
In 2), 1 liter of an emulsion type water-soluble coolant waste liquid corresponding to one kind of JISW was taken in a beaker, 0.5% by weight of magnesium sulfate heptahydrate was added, and the mixture was stirred for 15 minutes. Next, sulfuric acid was added, the pH was adjusted to 5.1, and the mixture was stirred for 5 minutes. Then, 0.5% by weight of polyaluminum chloride was added, and the lowered pH was adjusted to pH 5 again, followed by standing for 1 hour.
Table 3 shows the TOC measurement results of the clarified liquid in the lower layer portion.

[0033]

[Table 3]

As shown in Table 3, the cohesiveness and clarity are good. In particular, the water-soluble coolant equivalent to JISW1 contains a large amount of mineral oil and emulsifier. It became clear that more than 95% of these could be removed.

(Embodiment 4) Next, the processing amount was expanded to a practical level of 700 lit, and the processing effect was confirmed. For 700 liters of water-soluble coolant waste liquid corresponding to JIS W1 and W2 types used in Examples 1, 2 and 3, respectively, using the waste liquid treatment apparatus of the present invention shown in FIG. Separation (physical) treatment was performed to separate and remove flocs. Table 4 shows the TOC of the treated liquid. Experiment 13 is the treatment result of the emulsion type water equivalent to W1 type, and Experiment 14 is the treatment result of the microemulsion type water-soluble coolant waste liquid equivalent to W2 type.

[0036]

[Table 4]

As shown in Table 4, similar to the results of Examples 1 to 3, even if the practical capacity is 700 lit, the TOC
Values, cohesiveness and clarity were also good results. In addition, the recovery of flocs was good.

Example 5 A water-soluble coolant often contains a large amount of monoethanolamine, diethanolamine or triethanolamine in addition to an oil, an emulsifier, and an organic acid. However, even after the treatment according to the present invention, it can hardly be removed by the above method.
Ethanolamine can also be completely decomposed by the biological treatment described in 318489. Therefore, the treated waste liquid treated in Example 4 was further treated using a biological reactor. Table 5 shows the results.

[0039]

[Table 5]

As shown in Table 5, ethanolamine contained in the emulsion-type treatment waste liquid of Experiment 13 treated in Example 4 was not detected after about 1.5 days of biological treatment. The TOC value is 305 mg / lit and the COD value is 3
The BOD value was 50 mg / lit and the BOD value was 400 mg / lit. The microemulsion type of Experiment 14 was almost completely decomposed and removed in 1.9 days of biological treatment. Also, T
OC value is 1000 mg / lit, COD value is 1010 mg
/ Lit and BOD value were 1150 mg / lit. From these results, it is possible to remove components that inhibit biological treatment by the treatment method of the present invention, and it is effective as a pretreatment method for biological treatment of waste liquid containing amines.

[0041]

As described above, according to the present invention, magnesium sulfate heptahydrate is added in the process of treating a water-soluble emulsion waste liquid, so that it is easily soluble in water, and therefore stable. In addition to ensuring a sufficient processing capacity, it is also possible to pump liquid as an aqueous solution and to easily incorporate it into a general water treatment apparatus. On the other hand, since the pH value in the acid treatment can be kept at 5 to 5.5, the occurrence of troubles due to corrosion is significantly reduced, and therefore, the range of selection of the material of the apparatus is widened as compared with the conventional method, and the cost is reduced. The reduction has been achieved, and it has become environmentally friendly. In addition, by flocculating flocks with polyaluminum chloride, sludge having excellent dewatering properties was obtained, and the effect of achieving a significant reduction in transportation and incineration costs was obtained.

On the other hand, the waste liquid is circulated through a flotation tank, a measuring tank, and a buffer tank to carry out chemical treatment such as injection of chemicals.
Since the wastewater treatment apparatus is capable of performing batch processing for the physical processing of pressure flotation, equipment costs are small and the apparatus is compact. Furthermore, since measurement and processing can be performed without being affected by a change in waste liquid concentration or floc, stable processing can be performed, and an efficient waste liquid processing apparatus can be provided as a whole system.

Further, this waste liquid treatment apparatus can use the method for treating an aqueous water-soluble coolant waste liquid of the present invention, suppressing corrosion of the apparatus, injecting chemicals sequentially, and stabilizing pressure flotation. And could be processed efficiently.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a waste liquid treatment apparatus showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flotation separation tank 2 (Rotary floc) scraper 8 Magnesium sulfate pump 9 Sulfuric acid pump 10 Caustic soda pump 11 Poly aluminum chloride pump 14 Measuring instrument (pH electrode) 15 Measuring instrument (level sensor) 16 Measuring tank 17 Buffer tank 20 Supply Mouth 22 Discharge path 25 Circulation path

Continuing from the front page (72) Inventor Takashi Saeki 1-1-1, Fujikoshi Honcho, Toyama City, Toyama Prefecture Fujiuchi Co., Ltd. (72) Inventor Naoshi Okawa 1-1, Oikecho, Kosai-cho, Koka-gun, Shiga Prefecture Neos Co., Ltd. Within the Central Research Laboratory (72) Inventor Takashi Yonejima 1-1, Oike-cho, Kosai-cho, Koka-gun, Shiga Prefecture Neos Central Research Laboratory Co., Ltd.

Claims (8)

[Claims] An acid is added after adding an electrolyte having a divalent cation to an emulsion-based water-soluble coolant waste liquid so as to impart a property of being easily floated and separated to a mineral oil or other synthetic oil which is emulsion-stabilized. The emulsion is broken by adjusting the pH to 5-5.5, and then p
A method for treating an emulsion-based water-soluble coolant waste liquid, wherein an aggregate floc is enlarged by adding an inorganic flocculant while maintaining H5 to 5.5. 2. The method according to claim 1, wherein after adding the inorganic coagulant, the floc is floated and separated by a pressure flotation method. 3. The method according to claim 1, wherein the electrolyte having a divalent cation is magnesium sulfate heptahydrate. 4. The method according to claim 1, wherein the acid is sulfuric acid. 5. The method according to claim 1, wherein the inorganic flocculant is a polyaluminum chloride or a sulfuric acid band (aluminum).
A method for treating an emulsion-based water-soluble coolant waste liquid as described above. 6. A flotation tank having a scraper for discharging flocs at an upper part, a supply port for supplying chemicals, waste liquid, air and the like at a lower part, and a discharge path for discharging treated waste liquid. A measuring tank in communication with the flotation / separation tank at a lower portion and capable of supplying waste liquid and provided with a measuring device, a buffer tank for storing excess waste liquid from the measurement tank, and a flotation / separation tank for discharging the waste liquid in the buffer tank A wastewater treatment device, comprising: 7. The supply port is an outlet of the circulation path, and is capable of supplying a plurality of types of drugs, waste liquids, and pressurized air singly or as a mixture. Waste liquid treatment equipment. 8. The method for treating an emulsion-based water-soluble coolant waste liquid according to claim 1, wherein the waste liquid treatment apparatus according to claim 6 or 7 is used.