We Claim;
[1] A water treatment apparatus comprising:
a first electrode and a second electrode stored in a water treatment unit and provided so as to be separated from each other by a separator;
a power supply unit which applies voltage between the first electrode and the second electrode so that ions contained in treatment target water supplied from one side of the water treatment unit are adsorbed to the first electrode and the second electrode, thereby performing desalination and generating desalinated water; and
a washing water supply pump which causes washing water to flow from the other side of the water treatment unit to the one side of the water treatment unit, thereby washing the first electrode and the second electrode, wherein
the first electrode and the second electrode each include a plurality of flowable granular electrode members.
[2] The water treatment apparatus according to claim 1, wherein
the water treatment unit includes a pressing portion for pressing the first electrode and the second electrode.
[3] The water treatment apparatus according to claim 1

or 2, further comprising:
an additive supply unit which supplies an additive to the washing water; and
a control unit which determines whether or not to add the additive to the washing water.
[4] The water treatment apparatus according to claim 3, further comprising a reverse washing water tank which stores the desalinated water as the washing water.
[5] The water treatment apparatus according to claim 4, wherein
the additive supply unit supplies the additive to the washing water stored in the reverse washing water tank.
[6] The water treatment apparatus according to claim 5, wherein
the additive supply unit includes a plurality of additive storage tanks, and the plurality of additive storage tanks store additives of different types from each other.
[7] The water treatment apparatus according to claim 5 or 6, wherein
the additive supply unit is provided to a pipe connecting the water treatment unit and the washing water

supply pump.
[8] The water treatment apparatus according to claim 3, wherein
the additive supply unit generates the additive and directly injects the additive through an additive injection port provided to the water treatment unit.
[9] The water treatment apparatus according to claim 8, wherein
a plurality of additive injection ports are provided to the water treatment unit.
[10] The water treatment apparatus according to any one of claims 3 to 9, wherein
the control unit determines whether or not to add the additive to the washing water, on the basis of an ion removal rate obtained by dividing a difference between an electric conductivity of the treatment target water and an electric conductivity of the desalinated water by the electric conductivity of the treatment target water.
[11] The water treatment apparatus according to any one of claims 3 to 9, wherein
the control unit determines whether or not to add

the additive to the washing water, on the basis of an ion concentration of the desalinated water.
[12] The water treatment apparatus according to any one of claims 3 to 9, wherein
the control unit determines whether or not to add the additive to the washing water, on the basis of a hardness of the desalinated water.
[13] The water treatment apparatus according to any one of claims 3 to 9, wherein
the control unit determines whether or not to add the additive to the washing water, on the basis of a current value of current flowing through the water treatment unit during execution of the desalination.
[14] The water treatment apparatus according to any one of claims 3 to 9, wherein
the control unit determines whether or not to add the additive to the washing water, on the basis of a value of voltage between both ends of the water treatment unit at a time when the desalination is finished.
[15] The water treatment apparatus according to any one of claims 3 to 9, wherein

the control unit determines whether or not to add the additive to the washing water, on the basis of drop of voltage between both ends of the water treatment unit at a time of discharging after the desalination is finished.
i
[16] The water treatment apparatus according to any one of claims 3 to 9, wherein
the control unit determines whether or not to add the additive to the washing water, on the basis of pressure
) loss of the water treatment unit at a time when the desalination is finished.
[17] The water treatment apparatus according to any one of claims 1 to 16, further comprising a circulation path i through which the washing water flowing from the one side of the water treatment unit is sent to the other side of the water treatment unit.
[18] The water treatment apparatus according to any one ) of claims 1 to 17, wherein
the water treatment unit comprises a plurality of water treatment units connected in series.
[19] The water treatment apparatus according to claim 18, i wherein

the plurality of water treatment units share a reverse washing water tank which stores the desalinated water as the washing water.
[20] The water treatment apparatus according to any one of claims 1 to 19, further comprising an air pump which injects air into the water treatment unit during washing of the first electrode and the second electrode.
[21] A water treatment method comprising:
a desalination step of supplying treatment target water from one side of a water treatment unit which stores a first electrode and a second electrode provided so as to be separated from each other by a separator, and applying voltage to the first electrode and the second electrode so that ions contained in the treatment target water are adsorbed to the first electrode and the second electrode, thereby performing desalination and generating desalinated water; and
a washing step of washing the first electrode and the second electrode by causing washing water to flow from the other side of the water treatment unit to the one side of the water treatment unit, wherein
in the washing step, the second electrode is washed while flowable electrode members contained in the first

electrode and the second electrode are caused to flow.
[22] The water treatment method according to claim 21, wherein
the first electrode and the second electrode are pressed so as to be brought into a pressed state, the desalination step is executed while the pressed state is kept, and the washing step is executed after the pressed state is released.
[23] The water treatment method according to claim 21 or 22, further comprising a step of determining whether or not to add an additive to the washing water, between after the desalination step and before the washing step.
[24] The water treatment method according to any one of claims 21 to 23, wherein
the desalinated water generated in the desalination step is stored, and the stored desalinated water is used as the washing water.
[25] The water treatment method according to claim 23 or 24, wherein
after the first electrode and the second electrode are washed using the washing water to which a first additive

is added, the first electrode and the second electrode are washed using the washing water to which a second additive is added.
[26] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of an ion removal rate obtained by dividing a difference between an electric conductivity of the treatment target water and an electric conductivity of the desalinated water by an electric conductivity of the treatment target water.
[27] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of an ion concentration of the desalinated water.
[28] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of a hardness of the desalinated water.

[29] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of a current value of current flowing through the water treatment unit during execution of the desalination.
[30] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of a value of voltage between both ends of the water treatment unit at a time when the desalination is finished.
[31] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of drop of voltage between both ends of the water treatment unit at a time of discharging after the desalination is finished.
[32] The water treatment method according to any one of claims 23 to 25, wherein
whether or not to add the additive to the washing water is determined on the basis of pressure loss of the

water treatment unit at a time when the desalination is finished.
[33] The water treatment method according to any one of claims 21 to 32, wherein
in the washing step, the washing water flowing out from the one side of the water treatment unit is sent to the other side of the water treatment unit, whereby the washing water is circulated.