Abstract: This water treatment system is provided with: a reverse osmosis membrane device; a biofilm treatment device that has a carrier, on a surface of which is formed a biofilm, and that treats water to be treated before the water to be treated is transmitted through the reverse osmosis membrane device; and at least one of a water to be treated stoppage period circulation means and a water to be treated stoppage period supply means that are driven when the intake of new water to be treated is stopped. The water to be treated stoppage circulation means supplies and circulates water to be treated from a water to be treated discharge outlet side of the biofilm treatment device to a water to be treated supply port side. The water to be treated stoppage period supply means supplies new water to be treated to the biofilm treatment device.

Abstract: An object is to provide a pretreatment device of seawater capable of growing and maintaining a biofilm in a good state on each of a plurality of filters connected in series, by supplying nutrients appropriately to the filters. A pretreatment device of seawater is used in removing salt from the seawater to obtain freshwater, and includes: a supply duct (21) through which the seawater is to be supplied; a plurality of filters (16) including a particulate filtering material and a biofilm; connecting tubes (23) which connect the plurality of filters in series; a plurality of bypass tubes (24) each of which connects corresponding one of the plurality of filters to the supply duct; and a plurality of regulating valves (26) each of which is disposed in corresponding one of the plurality of bypass tubes to regulate a flow rate.

Abstract: A water treatment device includes a primary unit having a plurality of primary elements as reverse osmosis membrane devices disposed in parallel with each other to separate water to be treated into primary condensed water and fresh water; a pump which feeds the water to be treated from the upstream side of the primary unit to the primary unit; a secondary unit having secondary elements which are provided to be fewer in number than the primary elements and separate the primary condensed water into secondary condensed water and fresh water; a sub-element which separates one of the water to be treated and the primary condensed water; and a mode switching unit which switches the sub-element between a primary mode of being used as the primary element in the primary unit and a secondary mode of being used as the secondary element in the secondary unit.

Abstract: A water treatment device (1) includes a primary unit (U1) having a plurality of primary elements (E1) as reverse osmosis membrane devices disposed in parallel to each other to separate water to be treated (SW) into primary condensed water (CW1) and fresh water (FW1); a pump (P) which feeds the water to be treated (SW) to the primary unit (U1); a secondary unit (U2) having secondary elements (E2) as reverse osmosis membrane devices, the secondary elements (E2) being provided in smaller number than the primary elements (E1) and disposed in parallel to each other to separate the primary condensed water (W1) into secondary condensed water (CW2) and fresh water (FW2); and a switching unit (2) provided only in the secondary unit (U2) among the primary unit (U1) and the secondary unit (U2) to separate at least one of the plurality of secondary elements (E2) so that treatment is disabled.

Abstract: A water treatment device (1) includes a primary unit (U1) having a plurality of primary elements (E1) as reverse osmosis membrane devices disposed in parallel to each other to separate water to be treated (SW) supplied from an upstream side into primary condensed water (CW1) and fresh water (FW1); a pump (P) which feeds the water to be treated from the upstream side of the primary unit to supply the water to be treated to the primary unit; a secondary unit (U2) having secondary elements (E2) as reverse osmosis membrane devices, the secondary elements being provided in smaller number than the primary elements and disposed in parallel to each other to separate the primary condensed water into secondary condensed water (CW2) and fresh water (FW2); and a reflux unit (2) which refluxes a part of the secondary condensed water between the primary unit and the secondary unit.

Abstract: Provided are a water treatment apparatus and a water treatment method capable of performing a significant water quality evaluation of treated water before the filtration process, and capable of rapidly responding to a change in water quality of the treated water. A water treatment apparatus of the present invention includes a treated water filtering unit which filters treated water supplied from a treated water line to become filtered water, a filtered water mixing unit which is provided in a treated water extraction line diverging from the treated water line to reduce a turbidity concentration in the treated water of the treated water extraction line to become measured water, and a water quality measuring unit which is provided at a rear stage of the filtered water mixing unit in the treated water extraction line and measures water quality of the measured water to evaluate the water quality of the treated water.

Abstract: A water treatment device includes a sub-reverse osmosis membrane device having a primary casing and a primary reverse osmosis membrane dividing the primary casing into a primary liquid passing part and a primary permeating part; a low pressure water feed pump feeding seawater to the primary liquid passing part at a pressure that is equal to or lower than an osmotic pressure of the seawater; a main reverse osmosis membrane device having a secondary casing and a secondary reverse osmosis membrane dividing an inside of the secondary casing into a secondary liquid passing part and a secondary permeating part; and a high pressure water feed pump feeding a primary treated liquid, which is a resultant product of the seawater passing through and flowing out of the primary liquid passing part, to the secondary liquid passing part at a pressure higher than an osmotic pressure of the primary treated liquid.

Abstract: An object is to provide a pretreatment device of seawater capable of growing and maintaining a biofilm in a good state on each of a plurality of filters connected in series, by supplying nutrients appropriately to the filters. A pretreatment device of seawater is used in removing salt from the seawater to obtain freshwater, and includes: a supply duct (21) through which the seawater is to be supplied; a plurality of filters (16) including a particulate filtering material and a biofilm; connecting tubes (23) which connect the plurality of filters in series; a plurality of bypass tubes (24) each of which connects corresponding one of the plurality of filters to the supply duct; and a plurality of regulating valves (26) each of which is disposed in corresponding one of the plurality of bypass tubes to regulate a flow rate.

Abstract: This water treatment system comprises: a reverse osmosis device (2); a biofilm treatment device (4) that has a media on the surface of which a biofilm is formed and that treats water to be treated (3) before passing through the reverse osmosis device (2); an oxidizing agent addition device (5) that adds an oxidizing agent to the water to be treated (3) at a stage before treatment with the biofilm treatment device (4) or adds an oxidizing agent to the water to be treated (3) at a later stage after treatment with the biofilm treatment device (4) and before treatment with the reverse osmosis device (2); and a reducing agent addition device (6) that neutralizes the oxidizing agent by adding a reducing agent to the early stage water to be treated (3) or the later stage water to be treated (3).

Abstract: This water treatment system is provided with: a reverse osmosis membrane device; a biofilm treatment device that has a carrier, on a surface of which is formed a biofilm, and that treats water to be treated before the water to be treated is transmitted through the reverse osmosis membrane device; and at least one of a water to be treated stoppage period circulation means and a water to be treated stoppage period supply means that are driven when the intake of new water to be treated is stopped. The water to be treated stoppage circulation means supplies and circulates water to be treated from a water to be treated discharge outlet side of the biofilm treatment device to a water to be treated supply port side. The water to be treated stoppage period supply means supplies new water to be treated to the biofilm treatment device.

Abstract: An embodiment of the present invention includes: a spiral type pressure vessel 15 in which a plurality of reverse osmosis membrane apparatuses 13-1 to 13-10 having spiral reverse osmosis membranes is connected through a permeated water pipe 14, and is housed in a connected state; a raw water supplying line that supplies raw water 11 into the pressure vessel 15; a concentrated water discharging line through which concentrated water 16 concentrated is discharged; a plug 17 that blocks the permeated water pipe 14 at the center of the reverse osmosis membrane apparatuses 13-1 to 13-10; a front-side permeated water line and a front-side permeated water line through which front-side permeated water 12-1 and rear-side permeated water 12-2 are discharged to the exterior, respectively, which are separated fore and aft, respectively, of the permeated water pipe 14 blocked by the plug 17; a pressure regulating valve 20 that is mounted in the raw water supplying line and regulates the supply pressure of the raw water 11;

Abstract: A desalination apparatus includes a pretreatment device 13 having a pretreatment membrane 13a that filters suspended matters in raw water 11 with added chlorine-containing water 12, a reverse osmosis membrane device 17 having a reverse osmosis membrane 16 that removes a salt content from filtrate water 14 supplied from the pretreatment device 13 to produce permeated water 15, and a reducing-agent injection device 30 that neutralizes the added chlorine on an upstream side of the reverse osmosis membrane device 17. The reducing-agent injection device 30 extracts a part 14a of the filtrate water 14, adds metering SBS solution 18 to the part, obtains a maximum change point (equivalence point) of the oxidation-reduction potential of a reducing agent and chlorine, obtains reducing-agent additive concentration (Csm) corresponding to the equivalence point, and supplies the SBS solution 18 corresponding to the concentration to the filtrate water 14 to thereby neutralize the chlorine.

Abstract: An embodiment of the present invention includes: a recycle line that brings a part of salt-enriched membrane separation concentrated water 26 back to the rear flow side of a pretreatment apparatus 12; a water discharge line that discharges the remained concentrated water into a sea area; and a control apparatus 31 that controls to adjust the ratio between the discharging amount of the discharging membrane separation concentrated water to be discharged into a sea area and the supplying amount of supplying seawater. A pH is set to be equal to or less than 7.3 by adding acid 21. The salt 18 is obtained from the dryer 19, and produced water (fresh water) 29 is obtained by combining evaporated water 28 supplied from the evaporator 16 with the permeated water 24 supplied from the reverse osmosis membrane apparatus 25.

Abstract: A high-pressure pump P1 that increases the pressure of raw water, a high-pressure reverse osmosis device including a high-pressure reverse osmosis membrane for concentrating a salt content in high-pressure feed water, a first drain valve mounted on a permeated water line for supplying the permeated water downstream and temporarily draining permeated water of an initial start-up from a discharge line, a low-pressure pump that is mounted on a permeated water line provided downstream of the first drain valve and reduces the pressure of the permeated water, a low-pressure reverse osmosis device including a low-pressure reverse osmosis membrane for concentrating a salt content in low-pressure feed water, and a second drain valve mounted on a discharge line at the concentrated water side of the low-pressure reverse osmosis device that temporarily discharges the low-pressure feed water of the initial start-up supplied to the low-pressure reverse osmosis device.

Abstract: A high-pressure pump P1 that increases the pressure of raw water, a high-pressure reverse osmosis device including a high-pressure reverse osmosis membrane for concentrating a salt content in high-pressure feed water, a first drain valve mounted on a permeated water line for supplying the permeated water downstream and temporarily draining permeated water of an initial start-up from a discharge line, a low-pressure pump that is mounted on a permeated water line provided downstream of the first drain valve and reduces the pressure of the permeated water, a low-pressure reverse osmosis device including a low-pressure reverse osmosis membrane for concentrating a salt content in low-pressure feed water, and a second drain valve mounted on a discharge line at the concentrated water side of the low-pressure reverse osmosis device that temporarily discharges the low-pressure feed water of the initial start-up supplied to the low-pressure reverse osmosis device.

Abstract: A desalination apparatus includes a first reverse osmosis membrane device 13 that removes a salt content from raw water supplied with predetermined pressure, a second reverse osmosis membrane device 15 that removes a salt content in first permeated water 12 from the first reverse osmosis membrane device 13, a first flow regulation valve 17 that regulates flow rate of first concentrated water 16 from the first reverse osmosis membrane device 13, a second flow regulation valve 19 that regulate flow rate of second concentrated water 18 from the second reverse osmosis membrane device 15, and a control device that measures a supply temperature of the raw water 11 by a thermometer 20, controls the first flow regulation valve 17 to maintain discharge amount of concentrated water constant, and controls the second flow regulation valve 19 to reduce a return amount of water.

Abstract: A method of cleaning a filtration membrane includes an alkaline treatment process for supplying an alkaline agent 24 to seawater 11 for a predetermined period of time and filtering the seawater 11, to which the alkaline agent 24 is supplied, through a reverse osmosis membrane 15 during a filtration treatment operation, and a neutralization treatment process for supplying an acid agent 26 to the seawater 11 for a predetermined period of time and filtering the seawater 11, to which the acid agent 26 is supplied, through the reverse osmosis membrane 15 after the alkaline treatment process.

Abstract: A desalination apparatus includes a pretreatment device 13 having a pretreatment membrane 13a that filters suspended matters in raw water 11 with added chlorine-containing water 12, a reverse osmosis membrane device 17 having a reverse osmosis membrane 16 that removes a salt content from filtrate water 14 supplied from the pretreatment device 13 to produce permeated water 15, and a reducing-agent injection device 30 that neutralizes the added chlorine on an upstream side of the reverse osmosis membrane device 17. The reducing-agent injection device 30 extracts a part 14a of the filtrate water 14, adds metering SBS solution 18 to the part, obtains a maximum change point (equivalence point) of the oxidation-reduction potential of a reducing agent and chlorine, obtains reducing-agent additive concentration (Csm) corresponding to the equivalence point, and supplies the SBS solution 18 corresponding to the concentration to the filtrate water 14 to thereby neutralize the chlorine.

Abstract: A desalination apparatus according to the present invention includes: a pretreatment device having a pretreatment membrane that filters a turbid content contained in raw water; a reverse osmosis membrane device having a reverse osmosis membrane that reduces a salt content contained in filtrate water supplied from the pretreatment device to produce permeated water; a first control valve that is provided between a high-pressure pump mounted on a filtrate water line through which the filtrate water is supplied from the pretreatment device to the reverse osmosis membrane device and the reverse osmosis membrane device, and temporarily decreases a supply pressure of the filtrate water; and the control device that operates the first control valve to perform suck-back control by which a pressure at the entrance of the reverse osmosis membrane device is decreased in a pulse-like manner during operation.

Abstract: An embodiment of the present invention includes: a spiral type pressure vessel 15 in which a plurality of reverse osmosis membrane apparatuses 13-1 to 13-10 having spiral reverse osmosis membranes is connected through a permeated water pipe 14, and is housed in a connected state; a raw water supplying line that supplies raw water 11 into the pressure vessel 15; a concentrated water discharging line through which concentrated water 16 concentrated is discharged; a plug 17 that blocks the permeated water pipe 14 at the center of the reverse osmosis membrane apparatuses 13-1 to 13-10; a front-side permeated water line and a front-side permeated water line through which front-side permeated water 12-1 and rear-side permeated water 12-2 are discharged to the exterior, respectively, which are separated fore and aft, respectively, of the permeated water pipe 14 blocked by the plug 17; a pressure regulating valve 20 that is mounted in the raw wares supplying line and regulates the supply pressure of the raw water 11;