Liquid treatment method and liquid treatment apparatus

1. A liquid treatment method using a liquid treatment apparatus, the method comprising:

(Ia) providing the liquid treatment apparatus comprising:

a first tank having an internal space for storing liquid mixture containing photocatalyst particles;

a light source for emitting ultraviolet light with which the photocatalyst particles contained in the liquid mixture stored in the internal space of the first tank are irradiated;

a second tank comprising a filtration membrane therein and having an internal space divided into a first chamber and a second chamber by the filtration membrane; the first chamber being surrounded by the second chamber;

a communication channel that establishes communication between the internal space of the first tank and the second chamber of the second tank;

a controller;

a filtering pump for decompressing the first chamber of the second tank;

a channel switch;

an extraction channel that establishes communication between the first chamber of the second tank and the channel switch through the filtering pump;

a return channel that establishes communication between the channel switch and the internal space of the first tank; and

a discharge channel that establishes communication between the channel switch and an outside of the liquid treatment apparatus,

wherein

the liquid mixture is guided from the internal space of the first tank to the second chamber of the second tank through the communication channel;

the guided liquid mixture is passed through the filtration membrane to provide a filtrate in the first chamber of the second tank, the filtrate being generated by passing the guided liquid mixture through the filtration membrane, while the first chamber is decompressed with the filtering pump;

the filtrate generated by passing the guided liquid mixture through the filtration membrane is sucked into the channel switch through the extraction channel with the filtering pump; and

the channel switch switching by the controller between a circulation state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is returned to the first tank through the return channel and a discharge state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is discharged to the outside of the liquid treatment apparatus;

(Ib) circulating the liquid mixture in the liquid treatment apparatus in such a manner that the channel switch is set to be the circulation state so as to return the filtrate generated by passing the guided liquid mixture through the filtration membrane to the first tank through the return channel; and

(Ic) switching the channel switch by the controller from the circulation state to the discharge state to discharge the filtrate generated by passing the guided liquid mixture through the filtration membrane to the outside of the liquid treatment apparatus, if a concentration of the photocatalyst particles contained in the first tank falls within a range of not less than a first threshold value and not more than a second threshold value.

2. The method according to claim 1 , further comprising:

(Id) treating the liquid mixture by irradiation of the liquid mixture with the light emitted from the light source in the discharge state.

3. The method according to claim 2 , wherein

in the step (Id), a polluted liquid is supplied to the first tank.

4. A liquid treatment method using a liquid treatment apparatus, the method comprising:

(IIa) providing the liquid treatment apparatus comprising:

a first tank having an internal space for storing liquid mixture containing photocatalyst particles;

a light source for emitting ultraviolet light with which the photocatalyst particles contained in the liquid mixture stored in the internal space of the first tank are irradiated;

a second tank comprising a filtration membrane therein and having an internal space divided into a first chamber and a second chamber by the filtration membrane, the first chamber being surrounded by the second chamber;

a communication channel that establishes communication between the internal space of the first tank and the second chamber of the second tank;

a controller;

a filtering pump for decompressing the first chamber of the second tank;

a channel switch;

an extraction channel that establishes communication between the first chamber of the second tank and the channel switch through the filtering pump;

a return channel that establishes communication between the channel switch and the internal space of the first tank;

a discharge channel that establishes communication between the channel switch and an outside of the liquid treatment apparatus,

wherein

the liquid mixture is guided from the internal space of the first tank to the second chamber of the second tank through the communication channel;

the guided liquid mixture is passed through the filtration membrane to provide a filtrate in the first chamber of the second tank, the filtrate being generated by passing the guided liquid mixture through the filtration membrane, while the first chamber is decompressed with the filtering pump;

the filtrate generated by passing the guided liquid mixture through the filtration membrane is sucked into the channel switch through the extraction channel with the filtering pump;

the channel switch switching by the controller between a circulation state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is returned to the first tank through the return channel and a discharge state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is discharged to the outside of the liquid treatment apparatus;

(IIb) circulating the liquid mixture in the liquid treatment apparatus in such a manner that the channel switch is set to be the circulation state so as to return the filtrate generated by passing the guided liquid mixture through the filtration membrane to the first tank through the return channel; and

(IIc) providing a notification of information showing that the circulation state can be switched to the discharge state by the controller, if a concentration of the photocatalyst particles contained in the first tank falls within a range of not less than a first threshold value and not more than a second threshold value.

5. The method according to claim 4 , wherein the information further shows a polluted liquid can be supplied to the first tank.

6. A liquid treatment apparatus, comprising:

a first tank having an internal space for storing liquid mixture containing photocatalyst particles;

a light source for emitting ultraviolet light with which the photocatalyst particles contained in the liquid mixture stored in the internal space of the first tank are irradiated;

a second tank comprising a filtration membrane therein and having an internal space divided into a first chamber and a second chamber by the filtration membrane, the first chamber being surrounded by the second chamber;

a communication channel that establishes communication between the internal space of the first tank and the second chamber of the second tank;

a filtering pump for decompressing the first chamber of the second tank;

a channel switch;

an extraction channel that establishes communication between the first chamber of the second tank and the channel switch through the filtering pump;

a return channel that establishes communication between the channel switch and the internal space of the first tank; and

a discharge channel that establishes communication between the channel switch and an outside of the liquid treatment apparatus,

wherein

the liquid mixture is guided from the internal space of the first tank to the second chamber of the second tank through the communication channel;

the guided liquid mixture is passed through the filtration membrane to provide a filtrate in the first chamber of the second tank, the filtrate being generated by passing the guided liquid mixture through the filtration membrane, while the first chamber is decompressed with the filtering pump;

the filtrate generated by passing the guided liquid mixture through the filtration membrane is sucked into the channel switch through the extraction channel with the filtering pump;

the channel switch switching between a circulation state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is returned to the first tank through the return channel and a discharge state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is discharged to the outside of the liquid treatment apparatus; and

the liquid treatment apparatus further comprises a controller which, in operation,

circulates the liquid mixture in the liquid treatment apparatus in such a manner that the channel switch is set to be the circulation state so as to return the filtrate generated by passing the guided liquid mixture through the filtration membrane to the first tank through the return channel; and

switching the channel switch from the circulation state to the discharge state to discharge the filtrate generated by passing the guided liquid mixture through the filtration membrane to the outside of the liquid treatment apparatus, if a concentration of the photocatalyst particles contained in the first tank falls within a range of not less than a first threshold value and not more than a second threshold value.

7. The liquid treatment apparatus according to claim 6 , wherein

the controller further, in operation,

treats the liquid mixture by irradiation of the liquid mixture with the light emitted from the light source in the discharge state.

8. The liquid treatment apparatus according to claim 7 , wherein

the controller further, in operation,

supplies a polluted liquid to the first tank in the discharge state.

9. A liquid treatment apparatus, comprising:

a first tank having an internal space for storing liquid mixture containing photocatalyst particles;

a light source for emitting ultraviolet light with which the photocatalyst particles contained in the liquid mixture stored in the internal space of the first tank are irradiated;

a second tank comprising a filtration membrane therein and having an internal space divided into a first chamber and a second chamber by the filtration membrane, the first chamber being surrounded by the second chamber;

a communication channel that establishes communication between the internal space of the first tank and the second chamber of the second tank;

a filtering pump for decompressing the first chamber of the second tank;

a channel switch;

an extraction channel that establishes communication between the first chamber of the second tank and the channel switch through the filtering pump;

a return channel that establishes communication between the channel switch and the internal space of the first tank; and

a discharge channel that establishes communication between the channel switch and an outside of the liquid treatment apparatus;

wherein

the liquid mixture is guided from the internal space of the first tank to the second chamber of the second tank through the communication channel;

the guided liquid mixture is passed through the filtration membrane to provide a filtrate in the first chamber of the second tank, the filtrate being generated by passing the guided liquid mixture through the filtration membrane, while the first chamber is decompressed with the filtering pump;

the filtrate generated by passing the guided liquid mixture through the filtration membrane is sucked into the channel switch through the extraction channel with the filtering pump;

the channel switch switching between a circulation state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is returned to the first tank through the return channel and a discharge state in which the filtrate generated by passing the guided liquid mixture through the filtration membrane is discharged to the outside of the liquid treatment apparatus;

the liquid treatment apparatus further comprises a controller which, in operation,

circulates the liquid mixture in the liquid treatment apparatus in such a manner that the channel switch is set to be the circulation state so as to return the filtrate generated by passing the guided liquid mixture through the filtration membrane to the first tank through the return channel; and

provides a notification of information showing that the circulation state can be switched to the discharge state, if a concentration of the photocatalyst particles contained in the first tank falls within a range of not less than a first threshold value and not more than a second threshold value.

10. The liquid treatment apparatus according to claim 9 , wherein the information further shows a polluted liquid can be supplied to the first tank.