JP2011255325A - Detoxification method and automatic treatment device for formalin waste liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: the slaked lime method is a method for changing formaldehyde into saccharide by adding slaked lime (calcium hydroxide) to formalin, and a solution after the slaked lime addition has low basicity (pH= about 12) as compared to the caustic soda method, so that the solution after the slaked lime addition is easy to be handled, and the saccharide is biodegradable, accordingly, the slaked lime method is a method for producing an environmentally friendly waste liquid, but treatment efficiency of the slaked lime method is poor because a calcium salt occurs as sludge.SOLUTION: Slaked lime is added to a formalin waste liquid to change formaldehyde into the saccharide, and thereafter nitric acid is added to dissolve the slaked lime by neutralization, so that the formalin waste liquid is detoxified to discharge the formalin waste liquid. By adding a disaccharide or a monosaccharide such as glucose to the formalin waste liquid, heating the formalin waste liquid, or intermittently stirring the formalin waste liquid, saccharification can be promoted. Because no calcium salt occurs, an easy-maintenance automatic treatment device can be constructed.

Description

  The present invention relates to a method for detoxifying formalin waste liquid and an apparatus for automatically carrying out the method.

Formalin is used not only as a raw material for phenol / urea resins, but also as a preservative and preservative for organs and biological tissues in medical facilities, and as a preservative for aquatic organisms in laboratory tests and laboratories. .
Thus, since formaldehyde as a main component has strong toxicity, it is required to dispose of used waste liquid after detoxifying it.

JP 2002-263661 A

In response, various detoxification methods have been proposed, but as described in Patent Document 1, typical ones are the activated sludge treatment method, the caustic soda method, and the slaked lime method.
Of these, the activated sludge treatment method utilizes the decomposition action by microorganisms. When the concentration of formalin waste liquid is high, it is diluted to a sufficiently low concentration and then put into activated sludge treatment to determine the microorganisms that live there. There is a tendency to increase the size of facilities in order to prevent damage.
In the caustic soda method, since the reaction is performed under strong alkali (2 to 3 mol / L), handling is accompanied by danger and it is necessary to give sufficient consideration to safety.
On the other hand, the slaked lime method is to add slaked lime (calcium hydroxide) to formalin to change formaldehyde into saccharides, and the solution after addition of slaked lime is less basic than the caustic soda method (pH = about 12). In addition, since saccharides can be biodegradable, it can be said to produce an environmentally friendly waste liquid, but calcium salts are generated as sludge and the processing efficiency is poor.

In fisheries-related tests, laboratories and medical institutions such as health centers and hospitals, the amount of formalin waste liquid generated annually is small and it is difficult to install large-scale equipment. In addition, environmental considerations have recently been strongly demanded.
Therefore, in order to solve the above-mentioned problems, the present invention aims to provide a novel and useful formalin waste liquid detoxification method that employs the slaked lime method as a principle and overcomes the disadvantages of generating calcium salts. And
Another object of the present invention is to provide a novel and useful formalin waste liquid detoxification method with improved treatment efficiency.
Furthermore, an object of the present invention is to provide an automatic processing apparatus that can efficiently carry out the above-described detoxification method of formalin waste liquid.

As a result of diligent research, the present inventor has found that when adding nitric acid for neutralization, slaked lime dissolves and can be discharged through a pipe, and the present invention has been completed based on this finding.
The invention of claim 1 is a method for detoxifying formalin waste liquid, and after adding slaked lime to formalin waste liquid to change formaldehyde into saccharides, it is possible to discharge formalin waste liquid by adding nitric acid and dissolving slaked lime by neutralization. This is a detoxification method characterized by detoxification.

  The invention of claim 2 is the detoxification method of the formalin waste liquid according to claim 1, characterized in that glucose is added to the formalin waste liquid together with slaked lime to change to sugars.

Invention of Claim 3 in the detoxification method of formalin waste liquid described in Claim 2,
It is a detoxifying method characterized by adding monosaccharide or disaccharide together with slaked lime to formalin waste liquor to change to saccharide.

  The invention of claim 4 is a method for detoxifying formalin waste liquid according to any one of claims 1 to 3, wherein slaked lime is added to the formalin waste liquid and then the change to sugars is promoted under heating and intermittent stirring conditions. Is a detoxification method characterized by

  The invention of claim 5 is an automatic processing apparatus for formalin waste liquid for carrying out the detoxification method of formalin waste liquid according to any one of claims 1 to 4, and contains and treats the processed material of formalin waste liquid or slaked lime. A treatment tank for stirring the workpiece in the treatment tank, a heating means for heating the workpiece in the treatment tank, a temperature sensor for measuring the temperature of the workpiece, A pH sensor for measuring the pH of the object to be treated, a level switch for detecting the liquid level of the object to be treated, formalin waste liquid supply means for supplying formalin waste liquid into the treatment tank, and nitric acid for supplying nitric acid into the treatment tank. A supply means, a discharge means for discharging the treated liquid detoxified in the treatment tank, and a control means for controlling the operation of each means, wherein the control means is a formalin waste liquid to be treated in advance. Based on the basis of the optimum operating parameters set, receives information from the sensor group by a program control, said an automatic processing apparatus characterized by operating each means for automatically carrying out the detoxification method.

  According to a sixth aspect of the present invention, in the automatic processing apparatus for formalin waste liquid according to the fifth aspect, the apparatus comprises a water supply means, and after the treated liquid is discharged out of the apparatus by the discharge means, the water is supplied into the treatment tank by the water supply means. It is configured to be supplied and stored, and the water is discharged by the discharge means before the treatment of the next formalin waste liquid, and the detection part of the pH sensor is always immersed in water or formalin waste liquid. It is an automatic processing device characterized.

If the detoxification method of the present invention is used, the processed liquid obtained is environmentally friendly, and the processing apparatus for carrying out the method can be designed compactly, and maintenance can be simplified without worrying about clogging of apparatus piping. Further, the processing efficiency can be improved by optimally setting the processing conditions.
Furthermore, the apparatus for carrying out the above detoxification method of the present invention can be easily automated as a result.

1 is a schematic perspective view of an automatic processing apparatus according to an embodiment of the present invention. It is a schematic perspective view in the processing tank of the automatic processing apparatus of FIG. It is an electrical block diagram of the automatic processing apparatus of FIG. It is a flow of the process sequence of the automatic processing apparatus of FIG. It is a photograph which shows the state after adding slaked lime to formalin waste liquid and saccharifying. It is a photograph which shows the state at the time of adding saccharified lime to the formalin waste liquid of FIG. 5, and also adding sulfuric acid, hydrochloric acid, and nitric acid, respectively. It is a photograph which shows the state immediately after adding slaked lime or slaked lime, and glucose to the neutralization buffer formalin waste liquid containing a phosphate. It is a photograph which shows the state 15 hours after the state of FIG. It is a photograph which shows the state immediately after adding various saccharides to the neutralization buffer formalin waste liquid containing a phosphate. It is a photograph which shows the state after 15 hours from the state of FIG.

Embodiments of the present invention will be described below.
First, the detoxification method will be described in the order of steps.
(1) Add slaked lime to formalin waste liquid.
Add slaked lime to formalin wastewater to convert formaldehyde into sugars.
In addition, it is conventionally known that formaldehyde undergoes a condensation reaction to be changed into saccharide by adding slaked lime as described in Patent Document 1.
Since the preferred amount of slaked lime varies depending on the concentration of formaldehyde in the formalin waste liquid and the composition of the formalin waste liquid, a sample of the formalin waste liquid to be treated is obtained in advance and the preferred amount of slaked lime is found by a preliminary test.

Addition of glucose facilitates the conversion of formaldehyde to saccharides, so it is preferable to add glucose. In particular, formalin waste liquids from medical institutions are neutralized by adding phosphates such as potassium phosphate and sodium phosphate for pH buffering. In such cases, formaldehyde is not added even if slaked lime is added. It is difficult to change to sugar. However, formaldehyde is rapidly changed to saccharide by adding glucose.
Since the preferred amount of glucose used also varies depending on the formalin waste solution to be treated, a sample of the formalin waste solution to be treated is obtained in advance, and the preferred amount of glucose is found by a preliminary test.
The contribution mechanism of glucose to the change of formaldehyde to saccharide has not been elucidated yet.

  During the saccharification treatment, slaked lime settles without dissolving, so the cycle of stirring and standing is repeated to increase the chances of efficient contact between formaldehyde and slaked lime, or heating to about 40-60 ° C. Thus, it is preferable to accelerate the change of formaldehyde to saccharides to shorten the treatment time or reduce the amount of slaked lime used.

(2) Nitric acid is added after the formaldehyde in the formalin waste liquid is changed to sugars.
Slaked lime dissolves quickly when nitric acid is added. When sulfuric acid is added as an acid, calcium sulfate that is not dissolved by the acid (the main component of gypsum) is formed, so sulfuric acid is not suitable as an acid.
In order to completely dissolve slaked lime, it is recommended to set the amount of use so that the formalin waste liquid becomes acidic at pH = 4.
As a result of the above treatment, the formalin waste liquor has been changed to a saccharide-containing liquid, and can be discharged out of the apparatus as it is. However, since the treated liquid is weakly acidic when the pH is adjusted to about pH = 4 as described above, when discharged into public water bodies, a normal wastewater treatment facility such as sludge activation treatment is used. Or through a catalytic oxidation facility.

  In addition, even if hydrochloric acid is added, it will dissolve to some extent, but if hydrochloric acid is added to the actual waste liquid, there is a risk of generating chlorine-bonded substances in the waste liquid, and the safety of the waste liquid after neutralization is low. Become. Further, if the neutralized waste liquid is allowed to stand for about one week, it becomes dark black, and it is estimated that an undesirable reaction different from nitric acid occurs. Therefore, it is not preferable to add hydrochloric acid.

Next, an example of an automatic processing apparatus for automatically carrying out the above detoxification method will be described.
First, the configuration of the automatic processing apparatus 1 will be described with reference to FIGS.
In FIG. 1, the code | symbol 3 shows a box-shaped main body, and has the structure opened and closed with the front door 5. In FIG. A pair of casters 7 and stoppers 9 are attached to the four corners on the lower surface of the main body 3, and easy movement and stable installation at the movement destination are possible.
On the main body 3, a control box 11 is placed on the front side, and a treatment tank 13 is placed on the rear side.

Next, the structure of the processing tank 13 and the main body 3 will be described.
The upper opening of the processing tank 13 is closed by a lid 15. The lid body 15 is driven by the reflector 17 to move up and down, and is stably stationary at that position. Since the lid body 15 can be held above the treatment tank 13, the treatment tank The inside can be easily maintained.
As shown in FIG. 2, the lid 15 is provided with an inlet for slaked lime as a processing agent, and the inlet is opened and closed by an opening / closing cover 19. From the lower surface side of the lid 15, a pH sensor 21, a heater 23 as a heating unit, a temperature sensor 25, a rotation shaft 27 of a stirring unit including a rotation shaft and a stirring blade, and a level switch 29 are suspended. In addition, although conducting wires, such as a sensor mentioned above, are pulled out from the upper surface of the cover body 15, illustration is abbreviate | omitted for the convenience of visual recognition.

One end side of a formalin waste liquid supply line 31, a nitric acid supply line 33, and a water supply line 35 as supply means penetrates into the side of the treatment tank 13 and enters the inside. As shown in FIG. 1, each line enters the main body 3 on the way.
The other end side of the formalin waste liquid supply line 31 passes through the side part of the main body 3 and serves as a supply port to which one end of the hose can be connected. At the time of processing, one end of the hose is connected to this supply port, and the other end of the hose is connected to a reserve tank (not shown) that stores formalin waste liquid. A formalin waste liquid supply pump 32 (see FIG. 3) is inserted in the formalin waste liquid supply line 31.
The other end of the nitric acid supply line 33 is connected to a nitric acid reserve tank placed in the main body 3, and a nitric acid supply pump 34 (see FIG. 3) is inserted in the middle.
The other end side of the water supply line 35 penetrates the side part of the main body 3, and serves as a supply port to which one end of the hose can be connected. At the time of processing, one end of the hose is connected to this supply port, and the other end of the hose is connected to a water tap. A water supply valve 36 is inserted in the water supply line 35.

  In addition, one end of a drainage / drainage line 37 as a discharge means is connected to the bottom of the treatment tank 13. The drainage / drainage line 37 enters the main body 3 and is drawn out from the bottom of the main body 3. The other end is a drainage / drainage port to which a hose can be connected. At the time of processing, one end of this hose is connected to the above-mentioned drainage / drainage port, and the water in the processing tank 3 and the processed waste liquid are discharged out of the apparatus. An open / close valve 39 is provided at one end of the drainage / drainage line 37, and a drainage / drainage pump 38 is inserted in the middle.

Next, an electrical configuration surrounding the control box 11 centering on the control box 11 will be described with reference to FIG.
The control box 11 includes an analog board, a CPU board, TB, and a rotation axis controller for the stirring means. The analog board amplifies weak analog signals from the sensor group, Plays an intermediary. The CPU board includes a CPU (microprocessor) that reads and executes a program stored in the memory, and controls the heater 23 and the like by program control.

The front side of the control box 11 is an operation / display panel 41, which is provided with various switches for “preparation”, “start”, “stop”, and “in preparation”, “ LEDs for “automatic operation” and “parameter setting” are provided, and the LED corresponding to the operation content during the operation is lit to notify that. Further, the control box 11 can be opened and closed, and when opened, a “setting” switch is provided.
Below the operation / display panel 41, a display 43 for displaying the value of the sensor group is provided.
An alarm (not shown) for notification is also provided.

Next, a procedure for using the automatic processing apparatus 1 will be described.
(Operation parameter setting)
First, the “setting” switch is pressed, and the “parameter setting” LED is lit, and the operation parameters are set to the optimum one according to the formalin waste liquid to be processed. The set numerical value is displayed on the operation / display panel 41 described above.
The operating parameters include stirring time, stirring stop time, number of stirring cycles, heating temperature, formalin waste liquid supply time, nitric acid supply time, preferred discharge pH value, water supply time, drainage time, and the like.
After setting the operation parameters, the system is ready for operation. Moreover, since the operation parameter is permanently valid if it is set, it may be set once.

(Processing procedure by automatic processor)
This will be described according to the flow of FIG.
(Preparation mode)
When the “preparation” switch is manually pressed, in the automatic processing apparatus 1, the open / close valve 39 of the drainage / drainage line 37 opens and the drainage / drainage pump 38 operates to drain the water in the treatment tank 13. Is done. When the discharge is completed, an “alarm” sounds to notify that effect.

  Next, the open / close cover 19 of the lid 15 is manually opened, and slaked lime as a processing agent is charged from the charging port.

(Detoxification processing mode)
Waste liquid supply process:
When the “start” switch is manually pressed, the formalin waste liquid supply pump 32 of the formalin waste liquid supply line 31 is operated in the automatic processing apparatus 1 to supply the formalin waste liquid into the treatment tank 13.
Reaction process:
Next, when the level switch 29 confirms the supply of a predetermined amount of formalin waste liquid, the heater 23 releases heat under the monitoring of the temperature sensor 25 and the rotating shaft 27 of the stirring means rotates intermittently to formaldehyde sugars. Promote changes.
Stable process:
After the reaction process time elapses, the heater 23 and the like stop operating and enter a stabilization process.

Neutralization process:
When a predetermined stabilization time has elapsed, it is considered that the change of formaldehyde to saccharide has been completed, and this time, the nitric acid supply pump 34 of the nitric acid supply line 33 is operated to supply nitric acid into the treatment tank 13. The pH sensor 21 monitors and continues to be supplied until pH = 4. During the neutralization step, neutralization is promoted by the rotation of the rotating shaft 27.
Drainage process:
When the neutralization step is completed, the open / close valve 39 of the drainage / drainage line 37 is opened and the drainage / drainage pump 38 is operated to quickly drain the treated liquid out of the apparatus.
Water supply process:
When the draining process is finished, the water supply valve 36 of the water supply line 35 is operated to fill the treatment tank 13 with water.

Drainage process and water supply process:
In order not to leave the drained liquid in the treatment tank 13, drainage and water supply are performed again, and after the treatment tank 13 is filled with water, the fact is notified by an alarm and a series of steps is completed. .
Since the pH sensor 21 is immersed in the water stored in the treatment tank 13 after the completion, the pH sensor 21 is always immersed in some liquid to prevent drying.

As described above, according to the automatic processing apparatus 1, the process automatically proceeds except for manual operations such as pressing the “preparation” switch, inputting slaked lime, and pressing the “start” switch. The automatic processor 1 is operated with a household 100V or 200V power source. In addition, if necessary, an emergency stop can be performed by manually pressing the “stop” switch. Therefore, even a person who does not need skill can easily and safely perform the formalin waste liquid treatment. In addition, since the operation status can be stored and retained in the CPU board, if a power failure occurs during operation, the operation can be resumed from the middle of the process immediately before the power failure occurs by pressing the “Start” switch. Can do.
In addition, when also adding glucose, it will be input from the insertion port of the lid 15.

When the formalin processing capability by the automatic processing apparatus 1 was verified, the results in the following table were obtained.
Moreover, the safety | security with respect to aquatic organisms is confirmed by the toxicity test based on OECD for the processed liquid discharged | emitted from an automatic processing apparatus.

After changing the formalin solution into saccharides under the same conditions by the slaked lime method in the laboratory, nitric acid, hydrochloric acid, and sulfuric acid were added for neutralization, respectively, as shown in FIG. 5 and FIG. It was confirmed that slaked lime was completely dissolved only when nitric acid was added. When hydrochloric acid was added, it was difficult to distinguish with the photograph, but a slight residue was found on the bottom of the container.
The amount of each system used was 10% formalin solution: 200 mL and slaked lime: 10 g.
Each system container is immersed in a 40 ° C water tank, slaked lime is added to the container, and after first mixing by hand, let stand overnight, and then add 50% nitric acid, 50% hydrochloric acid and 25% sulfuric acid respectively. And neutralized. In all cases, the end point was around pH 4.

In the laboratory, slaked lime or slaked lime + glucose was added to a neutralized buffered formalin solution containing sodium phosphate, and changes after 15 hours were observed under the following treatment conditions.
The amount of each system used was 10% neutralized buffer formalin solution: 200 mL, slaked lime: 10 g, and glucose: 4 g (only glucose added system).
In the glucose addition system, glucose was added and mixed in a container containing a neutralized buffered formalin solution to confirm that the glucose was completely dissolved.
Then, each system container was immersed in a 40 degreeC water tank, slaked lime was added in the said container, and after mixing by hand first, it left still for 15 hours.
As a result, as shown in FIGS. 7 and 8, it was confirmed that formaldehyde was colored (saccharified) only in the glucose addition system.

In the laboratory, slaked lime + various sugars were added to a neutralized buffered formalin solution containing sodium phosphate, and changes after 15 hours were observed under the following treatment conditions.
The amount of each system used was 10% neutralized buffer formalin solution: 50 mL, various sugars: 1 g, and slaked lime: 2.5 g.
Various sugars were as follows.
Various saccharides were added and mixed in a container containing a neutralized buffer formalin solution, and it was confirmed that the various saccharides were completely dissolved.
Then, the container was immersed in a 40 degreeC water tank, slaked lime was added in the said container, and after mixing by hand first, it left still for 15 hours. Immediately after the start, it was as shown in FIG.

And 30 minutes after the start, the xylose, sorbose, fructose, and galactose addition systems began to be colored (saccharified). On the other hand, the addition system of mannose and sucrose was not colored at this point. In addition, although the glucose addition system was tested in Example 3, this glucose addition system was also not colored at this time. From this, it was found that the above four types of sugars have a higher effect of promoting saccharification than glucose (particularly sorbose).
And after 15 hours, as shown in FIG. 10, it was colored to the end point except for the system to which sucrose was added. Although coloring was observed with sucrose, it was found that the reaction rate for saccharification was very slow compared to other sugars.

  According to the detoxification method of the present invention, the implementation apparatus can be designed in a compact manner. In addition, the equipment can be operated with a household power supply, and after the treatment agent is charged, the process automatically proceeds to the drainage of the treated liquid and the subsequent water supply, and no waste mud is produced. Just do it. Therefore, it is very convenient to use it in a room of a facility such as a laboratory or a hospital.

DESCRIPTION OF SYMBOLS 1 ... Automatic processing device 3 ... Main body 5 ... Front door 7 ... Caster 9 ... Stopper 11 ... Control box 13 ... Processing tank 15 ... Lid 17 ... Reflector 19 ... Opening / closing cover 21 ... pH sensor 23 ... heater 25 ... temperature sensor 27 (rotary shaft) 29 ... level switch 31 ... formalin waste liquid supply line 32 ... formalin waste liquid supply pump 33 ... nitric acid supply line 34 ... Nitric acid supply pump 35 ... Water supply line 36 ... Water supply valve 37 ... Drainage / drainage line 38 ... Drainage / drainage pump 39 ... Open / close valve 41 ... Operation / display panel 43 ... Display

Claims (6)

In the detoxification method of formalin waste liquid,
A detoxification method characterized in that after adding slaked lime to formalin waste liquor to change formaldehyde into saccharides, nitric acid is added and slaked lime is dissolved by neutralization to render the formalin waste liquor detoxable. In the detoxification method of formalin waste liquid according to claim 1,
A detoxification method characterized in that glucose is added to formalin waste liquor together with slaked lime to change to sugars. In the detoxification method of formalin waste liquid according to claim 2,
A detoxification method characterized by adding monosaccharide or disaccharide together with slaked lime to formalin waste liquor to change to saccharide. In the detoxification method of formalin waste liquid according to any one of claims 1 to 3,
A detoxification method characterized by accelerating the change to sugars under warming and intermittent stirring conditions after adding slaked lime to formalin waste liquor. In the automatic processing apparatus of formalin waste liquid for carrying out the detoxification method of formalin waste liquid according to any one of claims 1 to 4,
A processing tank for storing and processing the processed object of formalin waste liquid and slaked lime, a stirring means for stirring the processed object in the processing tank, and a heating means for heating the processed object in the processing tank; A temperature sensor for measuring the temperature of the object to be processed, a pH sensor for measuring the pH of the object to be processed, a level switch for detecting the liquid level of the object to be processed, and a formalin waste liquid supply for supplying formalin waste liquid into the treatment tank Means, nitric acid supply means for supplying nitric acid into the treatment tank, discharge means for discharging the treated liquid detoxified in the treatment tank, and control means for controlling the operation of each means. ,
The control means receives information from the sensor group by program control based on optimum operation parameters set in advance based on the formalin waste liquid to be treated, and automatically executes the detoxification method by operating each means. An automatic processing device characterized by: In the automatic processing apparatus for formalin waste liquid according to claim 5,
Water supply means, and after the treated liquid is discharged out of the apparatus by the discharge means, water is supplied and stored in the treatment tank by the water supply means, and the water is discharged by the discharge means before the treatment of the next formalin waste liquid. An automatic processing apparatus which is configured to be discharged and in which the detection part of the pH sensor is always immersed in water or formalin waste liquid.