JP2001340844A - Method and apparatus for sterilizing wastewater containing microorganism and/or virus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for sterilizing wastewater containing microorganisms and/or viruses by the use of a heat exchanger in which the clogging of piping is prevented, and an apparatus for the method. SOLUTION: Wastewater A to be sterilized which is estimated to contain the microorganisms and/or viruses, the pH of which is adjusted so that the constituent proteins of the microorganisms and/or the viruses are not precipitated even after being denaturated by the sterilization, is passed through the heat exchanger 6 and kept at a necessary temperature for a necessary time to effect the sterilization. Preferably, the wastewater A is made alkaline to prevent the precipitation of the proteins even after being denaturated. More preferably, the wastewater A before the passage through the heat exchanger is heated by being heat-exchanged with the sterilized wastewater E kept at a sterilization temperature. The temperature and time for sterilization of the wastewater A are preferably adjusted so that the survival rate of the microorganism and/or the viruses after the sterilization is 1×10-6 or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to one or more microorganisms and / or viruses (bacteria, filamentous fungi, yeasts, cyanobacteria, protozoa, virus / phages, prions, etc .; the same applies hereinafter). The present invention relates to a method and apparatus for sterilizing contained wastewater, and particularly to a method and apparatus for inactivating waste liquid and wastewater from pharmaceutical facilities, factories, hospitals, and the like in which the presence of microorganisms and / or viruses is concerned.

[0002]

2. Description of the Related Art Conventionally, wastewater and wastewater (hereinafter sometimes referred to as microorganism- and / or virus-containing wastewater) from microorganisms and / or viruses from pharmaceutical facilities, factories, and hospitals such as blood products are concerned. In response, the following measures have been taken (edited by the Japanese Society for Infectious Diseases, “Hospital Infection Control Text”)
3rd revised edition, July 1998).

1) The drainage in the drainage pipe does not flow backward. If necessary, use an indirect drainage method in which the drainage system is once cut off from the atmosphere and drained into a water receiving container or drainage device that is directly connected to the general drainage system. 2) Prevent odor, sewage gas, sanitary insects, etc. from drainage pipes from entering the room. For this purpose, various traps are installed as needed. 3) Floor drains should be installed in a place where they can be easily inspected and connected to traps. 4) A drain pipe having a ventilation function shall be provided in the drain pipe. 5) To prevent clogging of drain pipes and to be able to cope with clogging. For this reason, a cleaning port is provided in a necessary place. 6) In highly clean areas, take measures to prevent drainage from becoming a source of pollution.

[0004] However, in the above-mentioned drainage measures, there is a possibility that wastewater which is likely to be infected is discharged out of the system without treatment. In addition, the dirt in the trap is before being inactivated, and there is a possibility that the dirt is transmitted through the dirt.

[0005] Therefore, microorganisms and viruses are inactivated (hereinafter, referred to as wastewater and wastewater) in which the presence of infectious microorganisms and / or viruses (hereinafter sometimes referred to as microorganisms and viruses) is concerned. In order to perform sterilization, pH adjustment and coagulation sedimentation treatment are applied, and the precipitated part is dehydrated and incinerated. The liquid phase part is disinfected with a disinfectant such as sodium hypochlorite, and then excess drug is removed. There is a case where a treatment method of neutralizing and discharging out of the system is adopted. In addition, the wastewater is temporarily stored in a kill tank (batch-type disinfection / disinfection device, high-pressure steam charging / holding device, or chemical (disinfectant) charging / holding device) or autoclave (high-pressure steam sterilizer), and the steam or chemical solution is directly processed by batch processing. There is a case where a processing method is employed in which the heat treatment or chemical treatment is performed after the introduction, and then the treatment is discharged outside the system.

[0006]

However, the treatment method of disinfecting with the disinfectant requires the addition of a large amount of chemicals.
In addition, since a large amount of energy is required for incineration, there is a problem that the running cost of the sterilization treatment rises accordingly. On the other hand, since the method of heat treatment or chemical treatment by directly charging steam or chemical liquid stored in the kill tank or autoclave is a batch type, a large-scale apparatus is required to treat a large amount of wastewater or parallel processing is required. A large number of devices are required for processing, and the equipment costs are increased, and the management and control of the devices become complicated.

In order to solve such a problem, a sterilization treatment using a heat exchanger can be considered. According to the heat exchanger, it is possible to continuously treat wastewater with a relatively small device. However, in the sterilization process using a heat exchanger,
Microorganisms and viruses solidified and denatured by the heat treatment, and other organic substances in the wastewater (for example, plasma proteins and the like in the wastewater of pharmaceutical facilities such as blood products) may precipitate and adhere to the piping, and may block the piping.

Accordingly, an object of the present invention is to provide a method and an apparatus for disinfecting wastewater containing microorganisms and / or viruses utilizing a heat exchanger without causing clogging of piping.

[0009]

Referring to the embodiment shown in FIG. 1, the method for disinfecting wastewater containing microorganisms and / or viruses according to the present invention comprises removing the wastewater A containing microorganisms and / or viruses to be heat-sterilized with the microorganisms and / or viruses. And / or heat exchanger 6 after adjusting the pH so that the constituent proteins of the virus do not precipitate even after denaturation by sterilization.
And the required sterilization time is maintained at the required sterilization temperature. Preferably, the waste water A has an alkali concentration at which the constituent proteins of microorganisms and / or viruses are dissolved even after denaturation by sterilization.

Referring to FIG. 1, the apparatus for sterilizing wastewater containing microorganisms and / or viruses according to the present invention comprises a microorganism and / or virus.
Or, a raw water receiving tank 1 for storing virus-containing wastewater A, a pH adjusting device 3 for adjusting the pH of the wastewater A in the raw water receiving tank 1, a heat exchange device 5 for maintaining the wastewater A at a required sterilizing temperature for a required sterilizing time, and the raw water receiving tank 1. A water supply pipe 10 for sending the waste water A to the heat exchange device 5 is provided. The waste water after the pH adjustment device 3 is adjusted to a pH at which the constituent proteins of the microorganisms and / or viruses do not precipitate even after denaturation by sterilization is supplied to the raw water supply pipe 10 by the water supply pipe 10. It is sent from the receiving tank 1 to the heat exchange device 5. Preferably, the pH adjusting device 3
Is an alkaline agent injection device for injecting an alkaline agent into the raw water receiving tank 1, and the injection device sets the wastewater A in the raw water receiving tank 1 to an alkali concentration at which the constituent proteins of microorganisms and / or viruses are dissolved even after denaturation by sterilization.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a pharmaceutical facility for blood products and the like.
CIP (Cleaning in Place) in factories, hospitals, etc. Automatic cleaning that is performed in a production state, in particular, without attaching additional equipment to the equipment or disassembling the production equipment.
same as below. 1) An embodiment of the apparatus of the present invention for sterilizing the waste water, washing waste water from the washing room, and other waste water including floor waste water as waste water A containing microorganisms and viruses by the heat exchange device 5 will be described. The wastewater A is temporarily stored in the raw water receiving tank 1, and the pH of the wastewater A is adjusted by the pH adjusting device 3 to a pH at which the constituent proteins of microorganisms and viruses do not precipitate even after denaturation by sterilization. When wastewater A contains a protein other than the constituent proteins of microorganisms and viruses, the pH of the protein can be adjusted to a value that does not precipitate after denaturation.

In the illustrated example, a pH adjusting device 3 is used as an alkaline agent injection device for injecting an alkaline agent into the raw water receiving tank 1, and the wastewater A in the raw water receiving tank 1 is subjected to denaturation of the microorganism and / or virus constituent proteins by sterilization. Adjusted to the concentration of alkali that dissolves. In the case of waste water A containing proteins other than the constituent proteins of microorganisms and viruses, the concentration of the protein can be adjusted to an alkali concentration that does not precipitate after denaturation. For example, the alkali concentration of the wastewater A is adjusted to pH> 9 by injecting an alkali agent,
The denatured protein can be dissolved. Preferably, drainage A
Is adjusted to pH> 11. However, as a result of the pH measurement of the wastewater A, if the wastewater A from the pharmaceutical facility or the like has a required pH, for example, the alkali having the above-mentioned alkali concentration, the pH adjustment by the pH adjusting device (alkali agent injection device) 3 is omitted. You may.

As the alkali agent for adjusting the alkali concentration of the waste water A, for example, sodium hydroxide (NaOH), calcium hydroxide (Ca (OH) ₂ ) and the like can be used. However, in the case of calcium hydroxide, there is a concern that an excessive amount of precipitation may occur. Sodium hydroxide has no risk of precipitation, and its concentration and flow rate are easily adjusted, so that it can be used easily.

Hereinafter, the present invention will be described with reference to FIG. 1 for the case of sterilizing the wastewater A adjusted to have the above-mentioned alkaline concentration. However, the pH of the wastewater A in the present invention is not limited to alkalinity. The pH is sufficient if the constituent proteins of the microorganisms and viruses do not precipitate even after denaturation by sterilization. Organic matter other than the constituent proteins of microorganisms and viruses in wastewater A (for example, plasma proteins in wastewater from pharmaceutical facilities such as blood products)
If the pH is such that the constituent proteins of microorganisms and viruses do not precipitate even after denaturation, it is considered that other organic substances in the wastewater will not precipitate after denaturation.

The wastewater A adjusted to the alkali concentration is sent to the heat exchange device 5 through the water pipe 10. The heat exchange device 5
A heat exchanger 6 that raises the temperature above the required sterilization temperature by heat exchange between the wastewater A and the steam G, and a holding tube 7 that holds the high-temperature wastewater D output from the heat exchanger 6 at the required sterilization temperature for the required sterilization time. Have. In the illustrated example, the heat exchange device 5 is provided with a temperature sensor 8 for measuring the outlet drain temperature from the heat exchanger 6 and a pressure sensor 9 for measuring the pressure in the holding tube 7, and is connected to the temperature sensor 8 and the pressure sensor 9. The control device (not shown) controls the temperature of the heat exchanger 6 according to the output signal of the temperature sensor 8 and the holding tube 7 according to the output signal of the pressure sensor 9.
Control of the drainage retention time.

In general, the sterilization assurance level (Sterility Assu) is defined as the survival rate of the viable cell count N after sterilization to the initial viable cell count N ₀ (= N / N ₀ ) is 1 / 100,000 (10 ⁻⁶ ) or less.
rance Level) (Sterilization and Disinfection Manual, written by Masayoshi Furuhashi, Nippon Medical Science Shinposha, January 1999, p37. For example, to kill 6 orders of magnitude of general bacteria, 121 ° C
Requires at least 9 minutes (preferably 15 minutes) and at 134 ° C for at least 0.45 minutes (preferably 3 minutes) (see “Sterilization and Disinfection Manual”, p. 49; Tsugio Sasaki et al. Sterilization and Microbial Killing Methods ”, Japan Standards Association, February 1998, p19). Further, in order to kill the hepatitis B virus by 6 digits, it is necessary to hold at 98 ° C. for 2 minutes and at 108 ° C. for 72 seconds. Six-digit killing of prions requires holding at 155 ° C. for 36 seconds. The holding tube 7 of the heat exchange device 5 holds the wastewater A at a required sterilization temperature and a required sterilization time according to the type of microorganisms and viruses. Preferably, the temperature of the waste water by the heat exchange device 5 and the time for holding the waste water in the holding tube 7 can be adjusted,
Six-digit killing can be ensured according to the type of microorganisms and viruses.

By maintaining the wastewater A from a pharmaceutical facility for blood products and the like at 135 ° C. for 90 seconds or more, the present inventor has found that almost all bacteria whose danger of contamination cannot be ruled out, It was experimentally confirmed that microorganisms and viruses including hepatitis viruses such as deficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV), and other viruses can be killed by six orders of magnitude.

Although the constituent proteins of microorganisms and viruses and other heat-solidified components in the wastewater are thermally denatured by the sterilization treatment of the holding tube 7, in the present invention, the wastewater is adjusted to a pH at which the protein does not precipitate even after the heat denaturation. Precipitation of the denatured and solidified protein on the inner wall of the heat exchanger 6 and the holding tube 7 can be suppressed. Further, even if the protein precipitates, it is dissolved by the temperature-raised wastewater E having the above-mentioned pH which continuously flows in, so that the adhesion to the inner wall of the pipe can be expected. Therefore, the sterilization apparatus of the present invention is easy to maintain and manage.

Further, since the clogging of the piping can be prevented, the sterilization of the continuously discharged wastewater can be stably continued for a long period of time. The continuous processing makes it possible to reduce the size of the apparatus, and it can be expected that equipment costs can be reduced. Moreover, the sterilizing effect of the heat exchange device 5 is not affected by the pH of the waste water. Holding tube 7
The sterilized drainage water E after passing through can be discharged together with general drainage water by subjecting it to an appropriate water temperature, subjecting it to a chemical neutralization treatment or a BOD treatment as needed.

In this manner, the object of the present invention is to provide "a method and an apparatus for disinfecting wastewater containing microorganisms and / or viruses utilizing a heat exchanger which does not cause clogging of piping".

[0021]

FIG. 1 shows a water supply pipe 10 between a raw water receiving tank 1 and a heat exchange device 5 in which a waste water A before passing through the heat exchange device 5 and a sterilized waste water E after maintaining the above sterilization temperature. Preheating devices 15 and 16 that increase the temperature by heat exchange are provided. The sterilized wastewater E after passing through the holding tube 7 is at a high temperature, and it is difficult to perform BOD treatment or the like as it is, and it is necessary to avoid discharging at a high temperature. In the illustrated example, the high-temperature wastewater E
Since the temperature of the wastewater A at a relatively low temperature is raised, the energy required for raising the temperature in the heat exchange device 5 can be reduced, and the running cost can be kept low.

In the illustrated example, two stages of preheating devices 15 and 16 are provided,
The water discharge pipes 14 and the water supply pipes 10 of the drainage waters E, F and H after passing through the holding tube 7 are connected to preheating devices 15 and 16.
Wastewater A of the raw water receiving tank 1 sent via the water pipe 10 is a preheating device
The temperature is raised at 15 and the outlet heated wastewater B is heated at the preheating device 16 and then sent to the heat exchanger 5 as the heated wastewater C.
On the other hand, the wastewater E discharged through the discharge pipe 14 is supplied to the preheating device 16.
In the preheating device 15, the temperature is reduced to a predetermined discharge temperature by heat exchange with the wastewater A, and then discharged as treated water H outside the system.

The apparatus shown in FIG. 1 was designed as a trial, assuming that 160 m ³ of the raw waste water A was sterilized in 10 hours. Assuming that the receiving temperature of the raw waste water A is maintained at 20 ° C. and maintained at 135 ° C. for 90 seconds in the heat exchanger 5, the heat transfer area of the preheaters 15 and 16 is 70 m ² , and the heat transfer of the heat exchanger 6 of the heat exchanger 5 is performed. Assuming that the area is 20 m ² , preheating wastewater B is 62 ° C, preheating wastewater C is 110 ° C, and high-temperature wastewater D is 135 ° C.
° C, medium temperature wastewater F is 87 ° C, and treated water H is 45 ° C. Also,
In this case, the energy required in the heat exchanger 5 for raising the temperature is 800 kg / hour at a steam pressure of 4 kg.

For comparison, a case where 160 m ³ of waste water A is sterilized at 135 ° C. for 90 seconds using a kill tank (direct steam injection type high-pressure steam sterilizer) or a single direct heat exchanger is used. Means that the required steam volume is 3,900 kg / h. In the case of performing the sterilization treatment with a single direct heat exchanger, in order to lower the temperature of the wastewater E after passing through the holding tube 7, it is necessary to separately apply a cooling energy or to reduce the time and space for cooling. From this trial design, as shown in Fig. 1,
It was confirmed that energy saving can be achieved by saving energy supplied from outside by providing 5 and 16.

Further, in FIG. 1, a pipe cleaning unit 20 is connected between the water discharge pipe 14 and the water supply pipe 10 of the treated water H after passing through the preheating devices 15 and 16 via valves 21 and 22. At the time of cleaning the pipeline composed of the water pipe 10, the heat exchange device 5, the preheating devices 15, 16, and the water discharge pipe 14, by switching the valves 21, 22, a closed flow path composed of the pipeline and the pipeline cleaning unit 20. To form In the present invention, the precipitation and adhesion of proteins can be suppressed by adjusting the wastewater to a required pH. However, it is also conceivable that inorganic substances in water other than proteins precipitate and adhere as scale. In order to solve this problem, for example, when the sterilization process is interrupted, the inside of the pipe is cleaned by circulating a scale removing agent or other cleaning liquid through a closed flow path including the pipe and the pipe cleaning unit 20.

In this case, it is preferable that the pipeline composed of the water supply pipe 10, the heat exchange device 5, the preheating devices 15, 16 and the water discharge pipe 14 is made of stainless steel, and nitric acid is used as a cleaning liquid. Nitric acid can dissolve the scale and form a passive film on the stainless steel pipe to increase the corrosion resistance. The formation of the passivation film can be expected to maintain the life of the device of the present invention for a long time. However, the cleaning liquid is not limited to nitric acid, and other suitable acids can be used.

The line cleaning unit 20 can be a prior art line cleaning CIP unit capable of dispensing a sufficient amount of a suitable temperature of cleaning liquid to any portion of the line. Also, the outlet steam of the heat exchange device 5 is guided to the pipeline cleaning unit 20 for reuse, so that all the lines (piping) and the devices after the unit 20 are thermally cleaned or thermally sterilized (Sterilization-in-place, SIP). ) Is also possible. By performing simple sterilization using steam as well as cleaning, the frequency of open inspection of the apparatus can be reduced, and maintenance can be facilitated.

The heat exchanger 6 of the heat exchanger 5 in FIG.
Although there is no particular limitation on the heat exchangers used as the preheating devices 15 and 16, for example, the use of a spiral heat exchanger shown in FIG. 2 can prevent scale adhesion. In the spiral heat exchanger 30 shown in FIG. 2, two plates are spirally wound from a central portion 32 to form two flow paths, and one end of each flow path communicates with an opening provided in the central portion 32. The other end of each flow path communicates with the opening via a pocket 35 provided at the outermost peripheral portion 34 of the spiral part 33. For example, the steam G flows into one flow path, the heated water C flows from the pocket 35 in the other flow path, and is discharged as the high-temperature waste water D from the central part 32. The spiral heat exchanger 30 has a single flow path and is smoother than the multi-tube heat exchanger. For this reason, as shown in FIG. 3, when the scale 37 adheres to the pipe 36 of the heat exchanger 30, the cross-sectional area of the adhered portion becomes smaller, the flow velocity increases, and a self-purifying action of peeling the scale 37 works. Therefore, the scale of the spiral heat exchanger 30 does not easily adhere to the spiral heat exchanger 30, and maintenance is easy. Moreover, chemical cleaning is easy. More preferably, a spiral heat exchanger made of stainless steel is used.

[0029]

As described above in detail, the method and apparatus for disinfecting wastewater containing microorganisms and / or viruses according to the present invention provide the wastewater to be heat-sterilized even after the constituent proteins of the microorganisms and / or viruses have been denatured by sterilization. Since the mixture is passed through a heat exchanger after having a pH that does not precipitate, the following remarkable effects are exhibited.

(A) It is possible to continuously treat a large amount of wastewater containing microorganisms and / or viruses while avoiding blockage of the piping. (B) Since continuous processing is possible, a space-saving and compact device can be provided. (C) By exchanging the wastewater before passing through the heat exchanger with the sterilized wastewater maintained at the sterilization temperature, energy can be saved by effectively using the exhaust heat. (D) It is possible to arbitrarily change the sterilization temperature (inactivation temperature) by changing the steam pressure, for example, and it is possible to easily cope with the sterilization of wastewater containing unknown bacteria and viruses in the future. (E) Since sterilization is performed by heat treatment, bacteria and viruses that cannot be sufficiently sterilized with a chemical solution can be reliably inactivated by adjusting the sterilization temperature and time. (F) Compared to the sterilization treatment using a chemical solution, the cost of the chemical solution can be reduced, so that the running cost can be reduced to about 1/10. Also, since a large amount of chemical solution is not used, there is little risk of polluting the environment.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a spiral heat exchanger.

FIG. 3 is an explanatory diagram of a scale adhering portion of a spiral heat exchanger.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Raw water receiving tank 3 ... pH adjuster 5 ... Heat exchanger 6 ... Heat exchanger 7 ... Holding tube 8 ... Temperature sensor 9 ... Pressure sensor 10 ... Water supply pipe 11 ... Infusion pump 12 ... Temperature sensor 14 ... Water discharge pipe 15 ... Preheating Device 16… Preheating device 20… Pipe washing unit 21… Valve 22… Valve 30… Spiral heat exchanger 31… Cover 32… Central part 33… Swirl part 34… Outermost part 35… Pocket 36… Piping in heat exchanger 37 ... Scale A ... Wastewater containing microorganisms and / or viruses B ... Heated wastewater C ... Heated wastewater D ... High temperature wastewater E ... Sterilized wastewater F ... Medium temperature wastewater G ... Steam H ... Treated water

Claims (12)

[Claims] A wastewater containing microorganisms and / or viruses to be heat-sterilized is adjusted to a pH at which the constituent proteins of the microorganisms and / or viruses do not precipitate even after denaturation by sterilization, and then passed through a heat exchanger to obtain a required sterilization temperature. A method for disinfecting wastewater containing microorganisms and / or viruses which is maintained for a time. 2. The method for sterilizing microorganism- and / or virus-containing wastewater according to claim 1, wherein the wastewater has an alkali concentration at which the constituent proteins of the microorganism and / or virus are dissolved even after denaturation by sterilization. 3. The method for sterilizing microorganism- and / or virus-containing wastewater according to claim 2, wherein said microorganism- and / or virus-containing wastewater is adjusted to said alkali concentration by adding sodium hydroxide. 4. The sterilization method according to claim 1, wherein when the wastewater contains proteins other than the constituent proteins, the pH or alkali concentration is settled after denaturing the proteins other than the constituent proteins. A method for disinfecting wastewater containing microorganisms and / or viruses that does not have a pH or alkali concentration. 5. The method according to claim 1, wherein the wastewater containing microorganisms and / or virus before passing through the heat exchanger is exchanged with sterilized wastewater after maintaining the sterilization temperature. A method for disinfecting wastewater containing microorganisms and / or viruses, the temperature of which is increased by the method described above. 6. The sterilization method according to claim 1, wherein the survival rate of microorganisms and / or viruses after sterilization is not more than 1 / 100,000 (10 ⁻⁶ ) before sterilization. A method for disinfecting wastewater containing microorganisms and / or viruses by adjusting the disinfection time. 7. A raw water receiving tank for storing wastewater containing microorganisms and / or viruses, a pH adjusting device for adjusting the pH of the wastewater in the raw water receiving tank, a heat exchange device for keeping the wastewater at a required sterilizing temperature for a required sterilizing time, and A water pipe for sending the wastewater in the raw water receiving tank to the heat exchange device, and the wastewater after setting the pH so that the constituent proteins of the microorganisms and / or viruses do not precipitate even after denaturation by sterilization by the pH adjusting device; A sterilizer for microorganism- and / or virus-containing wastewater sent from the raw water receiving tank to the heat exchanger. 8. The sterilizing apparatus according to claim 7, wherein the pH adjusting device is an alkali agent injecting device for injecting an alkaline agent into the raw water receiving tank, and the wastewater in the raw water receiving tank is discharged by the injection device with the microorganism and / or the microorganism. An apparatus for disinfecting wastewater containing microorganisms and / or viruses having an alkali concentration at which a virus constituent protein is dissolved even after denaturation by sterilization. 9. The sterilizing apparatus according to claim 7, wherein the wastewater containing microorganisms and / or virus before passing through the heat exchanger is maintained at the sterilizing temperature in the water supply pipe. A sterilizing device for wastewater containing microorganisms and / or viruses, which is provided with a preheating device that raises the temperature by replacement. 10. The line cleaning unit according to claim 7, wherein a drainage pipe for discharging sterilized wastewater after passing through the preheating device and the water supply pipe are connected via a valve. An apparatus for disinfecting microorganism- and / or virus-containing wastewater which forms a closed flow path composed of the water supply pipe, the heat exchange device, the preheating device, the water discharge pipe, and the pipeline cleaning unit by switching the valve during cleaning. . 11. The sterilizing apparatus according to claim 10, wherein said water supply pipe, heat exchanger, preheater and water discharge pipe are made of stainless steel, and said pipe washing unit supplies acid to said closed flow path. For sterilizing wastewater containing microorganisms and / or viruses. 12. The sterilizer for microorganism- and / or virus-containing wastewater according to claim 7, wherein the heat exchanger and / or the preheater is a spiral heat exchanger.