JPH10165492A - Treatment of drug waste using autoclave - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a perfect treatment operation method keeping conventional treatment capacity. SOLUTION: Drug waste, a matter to be treated, is put in an autoclave and the lid is tightly closed. Then pressurized steam is injected into the autoclave and the autoclave is pressurized and the temperature is elevated. After a prescribed time, the pressure in the autoclave is reduced. Pressurized steam is injected again, and the autoclave is pressurized and temperature is elevated. The process of pressurizing by pressurized steam and depressurizing is alternatively repeated for plural times. Installation of a vacuum pump is not required to reduce cost of equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating medical waste discharged from a medical institution by heating it with pressurized steam using an autoclave.

[0002]

2. Description of the Related Art Medical waste discharged from medical institutions and the like must be handled with special care due to its nature, and in principle, must be finally incinerated in an incinerator.
By the way, if the incinerator shuts down due to periodic inspection and repair or breakdown, medical waste generated during the shutdown period will be
Strict safe storage is required to prevent the growth of harmful microorganisms, new infections, and disease outbreaks. Medical waste guidelines, which are required to be publicly compliant, indicate that medical waste should be placed in an autoclave and heated at a predetermined temperature for a predetermined time.

[0003] Medical waste is usually carried out in a safe state stored in bags or containers. The unloaded medical waste is
It is placed in an autoclave and heat-treated in a container for safety. FIG. 1 shows a flow sheet of a standard steam heat treatment apparatus, and FIG. 5 shows a standard pattern of a temperature and an operation pressure of an object to be processed in a conventional heat treatment.
Conventionally, medical waste is put in an autoclave 1 and then sealed. First, in order to promote steam heating, the inside of the autoclave is depressurized using a vacuum pump 3 to discharge air therein. Then, pressurized steam is injected into the autoclave from the boiler 2 or the like, and the inside of the autoclave is heated to a predetermined temperature (121 ° C. in the above-mentioned current guideline). ,
It was cooled down and taken out. In the figure, reference numeral 4 indicates a control device, and reference numeral 5 indicates a steam trap.

[0004]

However, the above-mentioned standards are only the minimum necessary, and depending on the form and the storage amount of the container, there is a concern that the inside of the medical waste has been completely treated. is there. If the treatment is carried out at a high temperature for a long time in order to solve the anxiety, not only the economic burden will increase but also the required amount of medical waste may not be heat-treated. An object of the present invention is to provide an efficient and more complete processing method while maintaining the conventional processing capability.

[0005]

A first means of the present invention for achieving the above object is to put medical waste, which is an object to be treated, into an autoclave and seal it, and then inject pressurized steam into the autoclave. Pressurize, raise the temperature, reduce the pressure inside the autoclave after a predetermined time, then inject pressurized steam again, pressurize and raise the temperature, and alternately pressurize and reduce the pressure with the pressurized steam multiple times in the autoclave, A method for treating medical waste using an autoclave, characterized by repeating. Further, as a second means of the present invention, an object to be treated is placed in an autoclave and hermetically sealed, and the air in the autoclave is once discharged using a vacuum pump to reduce the pressure. Thereafter, pressurized steam was injected into the autoclave to increase the pressure and the temperature was increased.After a predetermined time, the pressure in the autoclave was decreased, and then pressurized steam was injected again to increase the temperature and the temperature was increased.
A method for treating medical waste using an autoclave, characterized in that pressurization with pressurized steam and pressure reduction are alternately repeated a plurality of times in an autoclave.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described with reference to the drawings. In the first means of the present invention, medical waste as an object to be treated is put in an autoclave and hermetically sealed, and pressurized steam is injected from the beginning to pressurize and raise the temperature. After pressurizing and raising the temperature, reduce the pressure in the autoclave after a predetermined time, further inject pressurized steam and pressurize, pressurize the object to be treated in the autoclave with pressurized steam and release the pressure multiple times, Repeat. FIG. 2 shows a general operation pattern of the internal pressure in the present invention. This operation has the effect of sequentially replacing the water vapor and condensed water that have permeated into the object and fall in temperature, and that allow high-temperature water vapor to permeate into the medical waste that has been difficult to raise in temperature by the conventional method. That is, by utilizing the present invention, even if the high-pressure steam that has penetrated into the medical waste is condensed by heat exchange with the medical waste, it is evaporated again by the reduced pressure and escapes to the outside of the medical waste. It is considered that the high-temperature pressurized steam again permeates the medical waste in the next cycle. In the conventional method, when the water vapor condenses inside the medical waste, it is considered that the condensed water hinders the invasion of high-temperature water vapor, and this requires a long time for complete treatment. The operating conditions vary depending on the required processing temperature, processing time, amount and form of the object to be processed, but when operating according to the above guidelines, it is preferable to use approximately 2.1 kg / cm ² G of pressurized steam. The time required for boosting and lowering the pressure per cycle is affected by the capacity of the autoclave, the throughput, and the like, but is generally 5 to 15 minutes. There is no need to provide a vacuum pump used in the conventional processing method, and equipment costs can be reduced.

A second means of the present invention is to put an object to be treated in an autoclave and hermetically seal it. First, the air in the autoclave is discharged by using a vacuum pump to reduce the pressure, and then pressurized steam is injected into the autoclave. Pressurize and raise the temperature. Usually, the pressure is reduced to about 10 ^-2 Torr. Up to this operation, there is no difference from the conventional processing method. In the present invention, after the pressurization and temperature rise, the pressure in the autoclave is reduced after a predetermined time,
Further, pressurized steam is injected and pressurized, and pressurization and release of the pressurized steam to the object in the autoclave are repeated a plurality of times. More reliable processing is possible as compared with the first means of the present invention.

[0008]

EXAMPLES After conducting some tests in connection with the present invention,
The contents will be described. The medical waste treatment device used in the experiment is the same as the conventional one shown in the flow sheet in FIG. The autoclave is a second-class pressure vessel (conforming to boiler and pressure vessel safety regulations) with an effective diameter of 500 mm and an effective length of 900 mm. The maximum operating pressure of the steam generation source is 10 kg / cm ² , and the amount of generated steam is reduced. Is 50
A small once-through boiler of 0 kg / hr was used. The capacity of the vacuum pump is 240 liters per minute, the ultimate pressure is 5 ×
10 ^-4 Torr, the control valve diameter is 1/2 inch,
An electromagnetic single-seat two-way valve with Cv = 4.0 was used, and a programmable controller was used as a control device. For safety, a simulated sample was prepared for the object to be treated instead of medical waste.

Experimental Example 1 A dry waste (with a water content of about 5) was placed in a low-density polyethylene garbage bag.
2.5% to 3 kg and 3 kg of the same dry waste as above.
A simulated sample was filled with a mixture of a wet waste to which 〜3 kg of water had been added, and this was placed in a cardboard box. In order to measure the actual processing temperature, four thermocouples were inserted at various points in the simulation sample, and the temperatures at the various points were continuously measured to obtain the processing temperature. In addition, the temperature of the space inside the vessel was separately measured to obtain the temperature inside the vessel.

First, the inside of the autoclave was depressurized to 10 ^-2 Torr by operating the vacuum pump, and was held for about 1 minute.
Then, pressurized steam was injected into the autoclave from the boiler, and the pressure in the vessel was increased to 2.1 kg / cm ² and maintained.
Next, the water vapor was released to make the pressure in the vessel almost atmospheric pressure. The time required from the injection of pressurized steam to the return of the internal pressure to the atmospheric pressure was adjusted to 10 minutes. When the same pressurized steam injection and pressure release operations were repeated twice, that is, 30 minutes after the temperature was raised, the treatment temperature reached substantially the same temperature as the inside temperature. During this time, the sample remained stationary. The measurement results are shown in FIG. 3 together with the operating pressure in the vessel.

Comparative Experimental Example 1 The sample and the method of implementation were the same as in Example 1, except that after the pressurized steam was injected into the autoclave, the steam pressure in the vessel was kept constant at 2.1 kg / cm ² . The processing temperature reached 116 ° C. 200 minutes after the injection of steam and reached 121 ° C. 300 minutes later, and the processing temperature substantially matched the inside temperature. During this time, the sample remained stationary.
The measurement result was the same pattern as shown in FIG. .

Experimental Example 2 An experiment was performed using the same apparatus as used in Example 1.
Samples were prepared by adding 600 ml of water to a disposable diaper, 1 kg of miso wrapped in a dry disposable diaper,
Similarly, wrapped 400g of ham, 422g of yaki pork
Were wrapped, and three wrapped pieces of konjac were prepared, each packed in a cardboard box and inserted into an autoclave. In order to measure the actual processing temperature, five thermocouples were inserted into each sample, and the temperature at each place was continuously measured to obtain the processing temperature. In addition, the temperature inside the vessel was separately measured to obtain the inside temperature.

First, the inside of the autoclave was depressurized to 10 ^-2 Torr by operating a vacuum pump and held for about 1 minute.
Then, pressurized steam was injected into the autoclave, and after 3 minutes, the internal pressure was increased to 2.1 kg / cm ² . After the internal pressure reached 2.1 kg / cm ² , it was opened 5 minutes later to bring the internal pressure to approximately atmospheric pressure. The time required from the injection of pressurized steam to the return of the internal pressure to the atmospheric pressure was adjusted to 10 minutes. Further, the same pressurized steam injection and pressure release operations are performed for 10
The cycle was repeated eight times in a minute cycle, and when approximately 85 minutes had elapsed from the injection of steam, the processing temperature became substantially equal to the temperature in the chamber at the time of pressure release. Therefore, the injection of pressurized steam and the operation of releasing the pressure were stopped, and the steam pressure in the vessel was kept constant. 180 minutes after injection of the pressurized steam, the temperature reached 121 ° C., and the processing temperature and the internal temperature coincided. During this time, the sample remained stationary. The measurement results are shown in FIG. 4 together with the operation pressure in the vessel.

Comparative Experimental Example 2 A comparative experiment was performed using the same apparatus and sample used in Experimental Example 2. However, after injecting the pressurized steam into the autoclave, the steam pressure in the vessel was increased to 2.1 kg /
It was kept constant at cm ^2. It took about 190 minutes to reach the temperature difference within 60 ° C., and about 230 minutes to reach the temperature difference within 40 ° C. FIG. 4 shows the temperature measurement results of the object to be treated.
Are also shown.

[0015]

According to the present invention, it is easy to quickly and uniformly heat medical waste to a required temperature to the inside thereof by using the conventional equipment as it is and by simply changing the operating conditions. .

[Brief description of the drawings]

FIG. 1 is a flow sheet of a standard steam heating apparatus.

FIG. 2 is a general operation pattern of the internal pressure in the present invention.

FIG. 3 shows the temperature measurement results of Example 1 and the operating pressure in the vessel.

FIG. 4 shows the temperature measurement results of Example 2 and the operating pressure in the vessel.
Of the temperature of the object to be treated and Comparative Example 2

FIG. 5 shows a standard pattern of a temperature of an object to be processed and an operating pressure in a conventional heat treatment.

[Explanation of symbols]

1: autoclave 2: boiler 3: vacuum pump 4: control device 5: steam trap

Claims (2)

[Claims] 1. After placing medical waste as an object to be treated in an autoclave and sealing it, pressurized steam is injected into the autoclave to increase the pressure and temperature. After a predetermined time, the pressure in the autoclave is reduced. A method for treating medical waste using an autoclave, comprising injecting pressurized steam again, pressurizing and raising the temperature, and alternately repeating pressurization with the pressurized steam and depressurization in the autoclave a plurality of times. 2. An object to be treated is placed in an autoclave, which is hermetically sealed. The air in the autoclave is evacuated by using a vacuum pump to reduce the pressure. Then, pressurized steam is injected into the autoclave, and the temperature is increased. After a predetermined time, the pressure in the autoclave is reduced, then pressurized steam is injected again to increase the pressure, the temperature is increased, and the pressurization and the pressure reduction by the pressurized steam in the autoclave are alternately repeated a plurality of times, characterized by being repeated. A method for treating medical waste using an autoclave.