JPH11290850A - Water treatment method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly sterilize even a protozoan small in size and hardly detected. SOLUTION: Since the heat treatment of the conc. soln. separated by a membrane treatment device 2 is performed at a time of filtering, for example, when a heating tank 7 is heated to 60 deg.C, even if a protozoan such as cryptosporidium or the like is mixed with the concn. soln., the protozoan can be certainly sterilized. Since heat treatment is performed in a filtering process and the backwashing process of the membrane treatment device 2 even if the protozoan such as cryptosporidium is bonded to the interior of the membrane treatment device 2, the protozoan peeled by backwashing can be certainly sterilized by heating. Therefore, even if the protozoan extremely small in size such as cryptosporidium and hardly detected is contained in raw water, it is prevented that the protozoan such as cryptosporidium again enters a filtering process.

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 water treatment in a water and sewage treatment plant, and more particularly to a water treatment suitable for killing small protozoa which are easily infected orally from raw water. .

[0002]

2. Description of the Related Art In a water treatment facility for water supply,
As a technique for solid-liquid separation of raw water, a combination of coagulation sedimentation and sand filtration is generally employed in many cases. But,
Solid-liquid separation by the combination of coagulation sedimentation and sand filtration requires a large area, and the operation and management of the facility is not always easy and requires a lot of manual labor. In addition, shortage of engineers in charge of maintenance and management of water purification facilities has become a problem especially in small and medium-sized water purification plants such as simple water supply systems. Therefore, a sophisticated and highly reliable membrane processing apparatus that does not require human intervention has been introduced in earnest.

On the other hand, in recent years, collective diarrhea has been caused by protozoa such as Cryptosporidium and Giardia contained in rivers and purified water serving as raw water for water supply, which has become a major social problem. The size of Cryptosporidium is 4.5-5.4 × 4.2-5.0 μm in the small species, and 6.6 in the large species.
７7.9 × 5.3-6.5 μm, and human infections are mainly small species. It has been found that when a person is infected with Cryptosporidium by oral ingestion or the like, diarrhea develops after an incubation period of about 3 days to about 1 week. The average number of Cryptosporidium contained in the surface water of rivers is only 0.04 / L, and it is very difficult to detect them. is there.

[0004] In addition, the oocysts of Cryptosporidium are covered with a shell having poor material permeability, so that they are not killed by chlorine at a practical concentration. According to the Ministry of Health and Welfare's “Temporary Guideline for Cryptosporidium in Waterworks”, when raw water is likely to be contaminated, the turbidity at the outlet of the filtration pond is always set to 0.
Should be maintained below 1 degree. In addition, as a prior art of a water treatment apparatus, JP-A-7-232196 can be cited.

[0005]

By the way, in the conventional water treatment apparatus, the raw water is solid-liquid separated into concentrated water and treated water by membrane treatment, and unnecessary water is removed from the separated concentrated water. Since the configuration is to return to the original purified water flow, there was a problem that the protozoa such as Cryptosporidium separated by the bending process and the membrane treatment entered the purified water flow again and could not be killed forever.

Further, in the membrane treatment, since the membrane permeation flow rate is greatly reduced due to fouling of the membrane, it is necessary to wash the membrane once per hour, for example, in order to suppress the decrease. Protozoa such as Cryptosporidium could not be killed at the time of membrane washing, and the water was returned to the original purified water flow, resulting in the same result as described above, and there was a danger that water purification operation would be threatened.

An object of the present invention is to provide a water treatment apparatus which can surely kill even a very small species and a hardly detectable protozoa such as Cryptosporidium in view of the above-mentioned problems of the prior art. is there.

[0008]

According to the method of the present invention, in the step of filtering raw water, the raw water is taken and solid-liquid separated into concentrated liquid and treated water by a membrane processor using a membrane processor. A wastewater treatment for removing unnecessary substances and draining the wastewater, a circulation treatment for returning the concentrated wastewater treated in the wastewater treatment step to the introduction side of the membrane treatment, and performing the membrane treatment and the wastewater treatment again;
The treated water separated by the membrane treatment is taken in, and at the time of the back washing step of the membrane treatment device, the treated water is guided to the membrane treatment device to wash the membrane treatment device and discharged from the membrane treatment device. This is a water treatment method having a backwashing treatment for introducing the treated water for washing to a drainage treatment in the same manner as the concentrated liquid, wherein a heat treatment for heating the concentrated liquid separated by the membrane treatment in the filtration step, A heating process for heating the cleaning treatment water discharged from the membrane processing device during the process.

In the apparatus of the present invention, a membrane treatment device for solid-liquid separation of the raw water into a concentrated liquid and a treated water when filtering the raw water, and a wastewater treatment for removing unnecessary substances from the separated concentrated water and draining the same. Tank, a circulating system for returning the concentrated wastewater from the wastewater treatment tank to the introduction side of the membrane treatment device, and taking in the separated treated water and guiding the treated water to the membrane treatment device during backwashing of the membrane treatment device. A washing system for cleaning the membrane processor, and a piping system for leading the cleaning treatment water discharged from the membrane processor to the wastewater treatment tank in the same manner as the concentrated solution, wherein between the membrane processor and the wastewater treatment tank And heating means for heating water flowing therethrough to a predetermined temperature.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 3 show one embodiment of a water treatment apparatus for carrying out the method of the present invention. A water treatment apparatus for carrying out the method of the present invention is roughly divided into a membrane treatment device 2 for solid-liquid separation of raw water from a supply tank 1 into a concentrated liquid and treated water as shown in FIG. The apparatus is provided with a wastewater treatment tank 3 for removing unnecessary substances from the concentrated liquid and draining it, and a membrane treatment tank 4 for taking in and storing the separated treated water.

The membrane processor 2 is provided with an electric valve 15
a, It is connected via a turbidity meter 12 and the raw water from the supply tank 1 passes therethrough, whereby solid-liquid separation into a concentrated liquid and treated water is performed. Therefore, the membrane processor 2 is not shown in detail,
It has separation means for solid-liquid separation. This separation means has, for example, a 'sieve' called a membrane pore, which is configured so as to completely exclude a larger substance and allow all the smaller substances to pass therethrough. Use a membrane module. Such a membrane pore is suitably of a size that can be excluded even by a small species of cryptosporidium as a small substance, for example, a size of 4.0 μ or less. The reason is that the size of Cryptosporidium, which mainly infects humans orally, is 4.5 to 5.4 × 4.2 to 5.0 μm.
In consideration of the fact that the diameter of the membrane is about m, and considering that a variant thereof is also present, it is desirable that the membrane pore has a size of about 1.0 μm. The supply tank 1 stores raw water from which substances of a certain size have been removed.

The wastewater treatment tank 3 is connected to the membrane treatment device 2 via a flowmeter 13, an electric valve 15b, and a heating tank 7, which will be described later. The wastewater treatment tank 3 removes suspended matter and protozoa such as Cryptosporidium giardia by being precipitated as suspended matter contained in the concentrated liquid, and the water from which they are removed is discharged as concentrated wastewater. Thus, in this example, a so-called sedimentation tank is formed. The sediment in the wastewater treatment tank 3 is periodically taken out. A circulation system 30 is provided between the wastewater treatment tank 3 and the supply tank 1, and the concentrated wastewater discharged from the wastewater treatment tank 3 by the circulation system 30 is on the upstream side of the membrane processor 2 again. It is circulated to the supply tank 1.

In this case, the circulation system 30 includes the wastewater treatment tank 3
Pipe 30a for leading concentrated wastewater from the tank, a second pipe 30b having one end connected to the end of the first pipe 30a and the other end provided above the supply tank 1, and a second pipe 3b.
0b and a third pipe 30c having one end connected to a connection portion of the first pipe 30a. A water temperature gauge 14, which will be described later, is provided in the first pipe 30a of the circulation system 30.
A circulation pump 11 and an electric valve 15e are provided in the second pipe 30b, and an electric valve 15f is also provided in the third pipe 30c. When the electric valve 15e is opened and the electric valve 15f is closed, the drive of the circulation pump 11 is performed. As a result, the concentrated wastewater from the wastewater treatment tank 3 returns to the supply tank 1. The concentrated wastewater from the wastewater treatment tank 3 can also be guided from the third pipe 30c as needed.

On the other hand, the membrane water tank 4 is connected to the treated water outlet of the membrane processor 2 via an inlet / outlet pipe 31. In this inlet / outlet pipe 31, an end pipe 31a located near the membrane treatment water tank 4
A motor-operated valve 15d is provided at an intermediate position, and a backwash pipe 31b is provided in parallel with the end pipe 31a. An electric valve 15c and a backwash pump 6 are installed in the backwash pipe 31b. The motor-operated valve 15c and the backwash pump 6 are not driven during the filtration process, and are driven when the membrane of the membrane processor 2 becomes dirty (washing the membrane processor 2).

That is, in the membrane treatment tank 4, the electric valve 15c is closed and the electric valve 15d is opened during the filtration step.
The treated water separated from the membrane processor 2 is stored by being sent in through the inlet / outlet pipe 31 and the end pipe 31a. Further, in the case of the backwashing step, when the motor-operated valve 15d is closed and the motor-operated valve 15c is opened and the backwashing pump 6 is driven, the treated water in the membrane treatment water tank 4 is pumped out, and the inlet / outlet pipe 31 is connected to the filter step. By flowing back and being supplied to the membrane processor 2,
The inside of the membrane processor 2 is washed, and the washed treated water flows from the membrane processor 2 toward the wastewater treatment tank 3. In this case, the membrane processor 2 is provided with an air pipe 32 through which air from the backwash blower 5 is fed, so that air is appropriately supplied into the membrane processor 2.

Further, the water treatment apparatus of this embodiment heat-treats the concentrated liquid separated from the membrane processor 2 in the filtration step and the backwashing water discharged from the membrane processor 2 in the backwash step. It has a heating means.

More specifically, the heating means includes a heating tank 7 provided adjacent to the wastewater treatment tank 3 and the heating tank 7.
And a control device 10 for controlling the temperature inside. The heating tank 7 is provided with the electric valve 15 of the wastewater treatment tank 3.
An aerator 8 having a heater 7a and an air diffuser 9 is provided at a position closer to b, and when the concentrated liquid is sent from the membrane processor 2, the concentrated liquid is heated by the heat of the heater 7a. . The heater 7a and the aeration device 8 are controlled by the control device 10.

The controller 10 controls the temperature of the concentrated wastewater discharged from the wastewater treatment tank 3 by controlling the heater 7a of the heating tank 7 based on the measurement signals of the turbidity meter 12 and the water temperature meter 14 during the filtration step. At a desired temperature.

This is because experiments have shown that protozoa such as Cryptosporidium can be killed when they are brought into contact with water at 60 ° C. for 3 minutes or more and heated. That is, when the turbidimeter 12 indicates a value that may include the protozoan in the raw water, the control device 10 sets the value to 0.1 in this example.
When the temperature becomes equal to or higher than the temperature, the heater 7a is controlled based on the measurement signals of the turbidity meter 12 and the water temperature meter 14 so that the temperature of the concentrated solution from the wastewater treatment tank 3 becomes 60 ° C. At that time, the heating tank 7 needs to be configured so that the concentrated liquid stays for 3 minutes or more.

The control device 10 controls the turbidity meter 12 to a value of 0.1.
When the measured value is less than the temperature, it is determined that the protozoan is not contained in the concentrated water, and the heater is set so that the temperature of the concentrated liquid from the wastewater treatment tank 3 becomes about 30 ° C. as shown in FIG. 7a. In this case, the temperature of 30 ° C.
As shown in FIG. 2, even if the turbidity value suddenly rises from a state where the turbidity value is less than 0.1 degree to a turbidity value (0.1 degrees or more) where the raw water contains protozoa, the membrane treatment device 2 The temperature is set to a value that can cope with the killing of the protozoa immediately in the heating tank 7 when the concentrated liquid comes from the heating tank 7.

The aeration device 8 is, as shown in FIG.
As soon as the turbidity value exceeds 0.1 degree, it is driven by the control device 10 for a predetermined time. That is, the timing of the operation / stop of the aerator 8 is controlled by the controller 10 under the conditions of [the value of the turbidimeter 12 is 0.1 degrees or more] and [the change per unit time of the turbidimeter 12 is positive]. The operation starts when the temperature of the water temperature gauge 14 at the outlet of the wastewater treatment tank 3 reaches 60 ° C. This is to prevent the malfunction of the aeration device 8 by the control device 10 also monitoring the change per unit time of the turbidity meter 12 at the same time.

Further, the control device 10 is configured to change the content of the backwashing process when the turbidity value is less than 0.1 in the filtration process and the backwashing process is performed thereafter. doing. That is, when the turbidity value is less than 0.1, as shown in FIG. 3A, treated water is supplied to the membrane processor 2 by the backwash pump 6 to perform water washing for 60 seconds. , 45 seconds later, air is supplied by the backwashing blower 5 to perform air cleaning for 15 seconds. Further, when the turbidity value is 0.1 degree or more, FIG.
As shown in the above, water washing with treated water for 90 seconds,
When 45 seconds have passed, air cleaning is performed for 45 seconds by the backwashing blower 5, and a cleaning time 1.5 times as long as that in FIG. When the backwash blower 5 sends air into the membrane processor 2, the air vibrates the membrane in the membrane processor 2 to facilitate removal of suspended matter, protozoa and the like clogged in the pores of the membrane. Used.

As described above, the control device 10 not only controls the heater 7a and the aeration device 8 based on the measured values of the turbidity meter 12 and the water temperature meter 14, but also controls each electric motor necessary to execute the filtration step. The valve and the circulation pump 11 are respectively controlled, and the electric valves, the backwash pump 6, and the backwash blower 5 necessary for executing the backwash process are respectively controlled.

Since the water treatment apparatus of the embodiment has the above-described configuration, an embodiment of the water treatment method of the present invention will be described next with reference to the description of the treatment steps. First, in the raw water filtration step, the supply tank 1 is opened by opening the electric valve 15a.
The raw water therein enters the membrane processor 2 via the turbidimeter 12, and is separated into a concentrated liquid containing protozoa and suspensions and treated water by the membrane processor 2.

Here, the separated treated water is supplied to the electric valve 15d.
Is opened and the motor-operated valve 15c is closed, so that it is guided to the membrane treatment water tank 4 and stored. On the other hand, the separated concentrated liquid has a flow meter 1
3. The wastewater is sent to the wastewater treatment tank 3 via the motor-operated valve 15b, and unnecessary substances are settled and dropped by gravity in the wastewater treatment tank 3, and other concentrated light water having a specific gravity other than that is drained together. The concentrated treated water from the wastewater treatment tank 4 is supplied to the circulation system 30.
The circulating pump 11 drives the circulating pump 11 so as to be guided to the supply tank 1 through the circulation system 30, and to form a circulation path from the supply tank 1 to the membrane treatment device 2 and the wastewater treatment tank 3 as raw water again.

At the time of the circulation, a heating tank 7 heated by a heater 7a is installed upstream of the sedimentation tank 3a of the wastewater treatment tank 3, and the heating tank 7 is moved downstream of the wastewater treatment tank 3 by the control device 10. The temperature is controlled based on the installed water thermometer 14 and the turbidity meter 12 installed between the supply tank 1 and the membrane treatment device 2, and the value of the turbidity meter 12 usually indicates the protozoa as shown in FIG. If it is not included, the temperature of the heating tank 7 is controlled to 30 ° C., and at this temperature, the aeration device 8 is stopped.

As shown in FIG. 2, the turbidity value of the raw water supplied to the membrane processor 2 exceeds 0.1 ° which is judged to contain a protozoan such as Cryptosporidium. Indicates that the inside of the heating tank 7 is 60
The temperature is controlled to rise to a temperature of ° C. Therefore, when the concentrated liquid containing the protozoa and the suspension is sent from the membrane treatment device 2 to the heating tank 7, the protozoa can be killed while flowing through the heating tank 7 for a desired time.

After that, the killed protozoa flow into the wastewater treatment tank 3, and the dead bodies adhere to the suspension and the like, settle by gravity, and are periodically removed when collected at the bottom. Suspended materials having a low specific gravity in the treatment tank 3 are discharged to the circulation system 30 as concentrated wastewater.

Therefore, in the method of the present invention, since the concentrated solution separated by the membrane processor 2 is heated during the filtration step, the temperature is 60 ° C., which is a temperature at which protozoa such as Cryptosporidium can be killed. Heating the heating tank 7 to ℃
Even if Cryptosporidium or the like is mixed in the concentrate, those protozoa can be surely killed. Protozoa such as Cryptosporidium can be killed when they are in contact with water at 30 ° C. for one hour or more.
Even in the case where the concentration is less than the degree, since there is a possibility that protozoa may be contained in the concentrated solution, it is preferable to lengthen the timing of discharging the sediment in the wastewater treatment tank 3 to the outside of the system in consideration of this.

In the back washing step of the membrane processor 2, the electric valve 15d is closed and the electric valve 15c is opened.
By driving the backwash pump 6, the membrane treatment tank 4
The treated water in the inside is introduced into the membrane processor 2, and the inside of the membrane processor 2 is washed. In this case, the measurement signal of the turbidimeter 12 is transmitted to the control device 10 during the filtration step performed so far, and the control device 10 performs the control based on the magnitude of the transmission signal as shown in FIG. (B) Perform any backwashing process. That is, in the backwashing step when the turbidity value becomes less than 0.1 degree in the filtration step, the backwashing treatment of FIG. 3A is performed, and the turbidity value becomes 0.1 degree or more. Figure 3
The backwashing process of (b) is performed.

When the inside of the membrane processor 2 is cleaned in this way, the cleaning water is used as the flow meter 13 and the electric valve 15b.
And is sent to the heating tank 7. Since the heating tank 7 is heated to 60 ° C. by the control device 10 as in the case of the filtration step, when cleaning treatment water is sent from the membrane processor 2, the protozoa contained in the cleaning treatment water are killed. be able to. Therefore, in the method of the present invention, since a heating process is performed not only in the filtration step but also in the backwashing step of the membrane processor 2, a parasite such as Cryptosporidium adheres to the membrane processor 2 by any chance. Even if it does, the protozoa removed by the backwash can be reliably killed by heating.

As a result, in the method of the present invention, the raw water is heated in the filtration step and the backwashing step of the membrane treatment device 2, so that compared to the prior art, the raw water contains extremely small species such as cryptosporidium. Even if protozoa that are difficult to detect are included, it is possible to prevent the protozoa such as Cryptosporidium from reentering the filtration step.

Further, in the apparatus of the present invention, as described above, the concentrated liquid separated from the membrane processor 2 in the filtration step and the backwash water discharged from the membrane processor 2 in the backwash step are heated. Since the heating means is provided, the above method can be performed accurately. Moreover, as a heating means,
The control apparatus 10 includes a water temperature meter 14, a turbidity meter 12, a heating tank 7, an aeration device 8, and a control device 10.
4. Since the inside of the heating tank 7 is controlled based on the measurement signal of the turbidity meter 12, the heating tank 7 can be controlled accurately.

Then, as in the embodiment, the heating tank 7 is installed upstream of the wastewater treatment tank 3 and the concentrated liquid flows from the heating tank 7 to the wastewater treatment tank 3 as it is, so that it is killed. Protozoa can be immediately precipitated, and the possibility that the suspension concentration of circulating water becomes high can be suppressed.

FIG. 4 shows another embodiment of the water treatment apparatus for carrying out the method of the present invention. In FIG. 4, the same reference numerals as those in FIG. 1 denote the same parts.

In this case, the apparatus shown in FIG. 1 is combined with an ozone generator. In an ozone generator, generally, air as a raw material is pressurized to about one atmosphere by a blower 18, then drained and cooled by a cooler of an air cooling / drying device 19, and then the alumina silica gel agent in the dryer is dehumidified. By the action, dry compressed air (dew point of about −60 ° C.) is generated. The dry compressed air is supplied to the ozone generator 2
By passing through the glow discharge by zero, it becomes ozonized air. Thereafter, the ozonized air is supplied to the ozone contact pond 16.
When the air is diffused through the ozone diffuser 17, the organic substances contained in the treated water sent from the membrane treatment water tank 4 are purified by an oxidation reaction with the ozonized air.
Since there is surplus ozone in the ozone contact pond 16 which does not dissolve in the water, the surplus ozone is
By being decomposed, the gas is exhausted as harmless.

In this embodiment, the heating tank 7 is heated by utilizing the exhaust heat of the blower 18 of the above-mentioned ozone generator. That is, the circulation pipe 2 having the circulation pump 23 so that water can be circulated in the heating tank 7.
2 is provided, and a heat exchanger 25 is installed between the circulation pipe 22 and the discharge pipe 24 of the blower 18. Then, the temperature rises (about 14 ° C.) due to the adiabatic compression of the air blower 18.
(0 ° C.), but the heat exchanges with the water in the circulation pipe 22 to heat the heating tank 7.

Therefore, according to this embodiment, the exhaust heat of the air blower 18 of the ozone generator is used as a heat source of the heating tank 7, and both the circulating water and the heater 7 are used as heat sources. As compared with the embodiment using only the heat source, the energy saving effect can be achieved correspondingly, which is economically advantageous.

In each of the embodiments, the example in which the heating tank 7 is provided adjacent to the wastewater treatment tank 3 is shown.
It is needless to say that the same function and effect can be obtained even if the device is installed independently of the above. Further, although an example in which a sedimentation tank for sedimenting suspended matters and protozoa is used as the wastewater treatment tank 3 has been described, the present invention is not limited to this, and may be applied to one having another treatment function.

[0040]

As described above, according to the first aspect of the present invention, during the filtration step, the heat treatment for heating the concentrated liquid separated by the membrane treatment, and during the backwash step, the membrane treatment device is used. And heat treatment for heating the cleaning water discharged from the water, so that even if protozoa such as Cryptosporidium are contained in the raw water, they can be surely killed by heating, and therefore, can be detected. Even if a protozoa which is difficult to be contained is contained, it is possible to prevent the protozoa such as Cryptosporidium from reentering the filtration step, which has an effect of improving reliability.

According to a second aspect of the present invention, there is provided a membrane treatment device, a wastewater treatment tank, a circulation system, and a piping system, and water flowing between the membrane treatment device and the wastewater treatment tank is maintained at a predetermined temperature. The above-described method and the invention can be carried out accurately.

[Brief description of the drawings]

FIG. 1 is a piping diagram showing one embodiment of a water treatment apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a control operation of a heater and an aerator when a turbidity value increases from less than 0.1 degrees to a value of 0.1 degrees or more.

FIGS. 3A and 3B are an explanatory diagram of backwashing when the turbidity value is less than 0.1 degree and an explanatory diagram of backwashing when the turbidity value is 0.1 degree or more (b).

FIG. 4 is a piping diagram showing another embodiment of the water treatment apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Supply tank, 2 ... Membrane processor, 3 ... Drainage treatment tank, 4 ... Membrane treatment water tank, 5 ... Backwash blower, 6 ... Backwash pump, 7 ... Heating tank, 7a ... Heater, 8 ... Aeration device, 9 … A diffuser, 10…
Control device, 11: circulating pump, 12: turbidity meter, 13: flow meter, 14: water temperature meter, 15a to 15f: electric valve, 16 ...
Ozone contact pond, 17 ... Ozone diffuser, 18 ... Blower, 1
9: air cooling / drying device, 20: ozone generator, 21: exhaust ozone treatment device, 22: circulation pipe, 23: circulation pump,
Reference numeral 24: blower discharge pipe, 25: heat exchanger, 30: circulation system, 30a: first pipe, 30b: second pipe, 30c: third pipe, 31: inlet / outlet pipe, 31a: end pipe, 31b: reverse Wash pipe, 32 ... air pipe.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takashi Goto, Inventor 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture Inside Kokubu Plant, Hitachi, Ltd. (72) Inventor Akihiko Okada 1-1-1, Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Kokubu Plant of Hitachi, Ltd.

Claims (5)

[Claims] In a raw water filtration step, a raw water is taken in, a membrane treatment is performed to solid-liquid separate the concentrated liquid and the treated water by a membrane processing device, and a wastewater is removed by removing unnecessary substances from the separated concentrated liquid. Treatment, the concentrated wastewater treated in the wastewater treatment step is returned to the introduction side of the membrane treatment, the circulation treatment for performing the membrane treatment and the wastewater treatment again, and the treated water separated in the membrane treatment is taken in. In the back washing step of the membrane processor, the treated water is guided to the membrane processor to wash the membrane processor, and the cleaning water discharged from the membrane processor is subjected to wastewater treatment in the same manner as the concentrated liquid. A water treatment method having a backwash treatment that leads to the above, wherein a heat treatment for heating the concentrated solution separated in the membrane treatment during the filtration step, and a wash discharged from the membrane treatment device during the backwash step A heat treatment for heating the treated water. 2. A membrane treatment device for solid-liquid separation of raw water into a concentrated liquid and treated water during filtration of raw water, a wastewater treatment tank for removing unnecessary substances from the separated concentrated water and draining the same, and a wastewater treatment. A circulation system that returns the concentrated wastewater from the tank to the introduction side of the membrane processor, and takes in the separated treated water, and when the membrane processor is backwashed, guides the treated water to the membrane processor to wash the membrane processor. And a piping system for guiding the cleaning treatment water discharged from the membrane treatment device to the wastewater treatment tank in the same manner as the concentrated liquid, and flows between the membrane treatment device and the wastewater treatment tank therebetween. A water treatment apparatus comprising heating means for heating water to a predetermined temperature. 3. The heating means has a heating tank installed in a piping system between a membrane treatment device and a wastewater treatment tank, and the heating means has a temperature capable of killing protozoa contained in raw water. The water treatment apparatus according to claim 2, wherein the temperature of the water treatment apparatus is increased. 4. When the turbidity value contained in the raw water supplied to the membrane processor reaches a predetermined value, the temperature of the heating tank is controlled to a temperature at which the protozoa can be killed, and the turbidity contained in the raw water is controlled. The water treatment apparatus according to claim 3, further comprising control means for controlling the temperature of the heating tank to be lower than a temperature at which the protozoa can be killed when the temperature value is equal to or less than a predetermined value. 5. The apparatus according to claim 1, further comprising an ozone generator for ozonizing the treated water in the membrane water tank, and heating means for heating the heating tank by exhaust heat generated from the ozone generator. Water treatment equipment.