Abstract: A desalination performance restoration agent for a cellulose acetate membrane contains: a solvent; and a modified polyvinyl alcohol mixed in the solvent. The modified polyvinyl alcohol has an acetyl group structure in at least part of polyvinyl alcohol.

Abstract: A desalination performance restoration agent for a cellulose acetate membrane contains: a solvent; and a modified polyvinyl alcohol mixed in the solvent. The modified polyvinyl alcohol has an acetyl group structure in at least part of polyvinyl alcohol.

Abstract: A desalination performance restoration agent for a cellulose acetate membrane contains: a solvent; and a modified polyvinyl alcohol mixed in the solvent. The modified polyvinyl alcohol has an acetyl group structure in at least part of polyvinyl alcohol.

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: A suspended-matter removing method and a suspended-matter removing apparatus are disclosed that require no sludge treatment facility, and inexpensively provide filtrate satisfying a water quality standard. The suspended-matter removing method includes: feeding a protrusion element to a filter layer formed by filling a solid filter material, adding a protrusion to a surface of the solid filter material; after feeding protrusion element, determining whether a protrusion has been added to the surface of the solid filter material, and when it is determined that the protrusion has been added, reducing a feeding amount of the protrusion element as compared with when adding the protrusion; forming a biofilm on the surface of the solid filter material; and passing water to be treated containing suspended matters through the filter layer having the solid filter material added with the protrusion in a state in which the feeding amount of the protrusion element is reduced.

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 reverse osmosis membrane filtering device includes: a water-collecting member including at least one water collecting pipe, and having a plurality of sections each of which has a plurality of water collecting apertures; at least one filter assembly disposed around the plurality of sections, the at least one filter assembly including a filter member including a reverse osmosis membrane; at least one insertion tube disposed inside the water-collecting member and defining a plurality of permeate-water channels corresponding to the plurality of sections inside the water-collecting member in cooperation with at least one seal member; and a pressure adjusting device configured to increase a pressure of at least one of the plurality of permeate-water channels to a pressure higher than that of another one of the plurality of permeate-water channels.

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: Provided is a reverse osmosis membrane cleaning apparatus (10) which includes a membrane module (1) including a reverse osmosis membrane, a cleaning water tank (11) which stores cleaning water, a heater (13) which heats cleaning water supplied from the cleaning water tank (11) to the reverse osmosis membrane, and a temperature control device (17) which controls the heater so that a temperature of the cleaning water heated by the heater (13) is higher than 45° C. and not higher than 60° C.

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: A suspended-matter removing method and a suspended-matter removing apparatus are disclosed which require no sludge treatment facility, and inexpensively provide filtrate satisfying a water quality standard. The method includes: feeding a protrusion element to a filter layer formed by filling a solid filter material, adding a protrusion to a surface of the solid filter material; after feeding of the protrusion element, determining whether or not a protrusion satisfying a preset standard has been added to the surface of the solid filter material, and when it is determined that the protrusion has been added, reducing a feeding amount of the protrusion element as compared with when adding the protrusion; and passing water to be treated containing suspended matters through the filter layer having the solid filter material added with the protrusion in a state in which the feeding amount of the protrusion element is reduced.

Abstract: A suspended-matter removing method and a suspended-matter removing apparatus are disclosed that require no sludge treatment facility, and inexpensively provide filtrate satisfying a water quality standard. The suspended-matter removing method includes: feeding a protrusion element to a filter layer formed by filling a solid filter material, adding a protrusion to a surface of the solid filter material; after feeding protrusion element, determining whether a protrusion has been added to the surface of the solid filter material, and when it is determined that the protrusion has been added, reducing a feeding amount of the protrusion element as compared with when adding the protrusion; forming a biofilm on the surface of the solid filter material; and passing water to be treated containing suspended matters through the filter layer having the solid filter material added with the protrusion in a state in which the feeding amount of the protrusion element is reduced.

Abstract: A regeneration method for a filtration apparatus, a filtration apparatus, and a water treatment apparatus are disclosed that shorten a time required until stabilization of water quality of filtrate after backwashing, and stably provide filtrate satisfying a desired water quality standard. The regeneration method for a filtration apparatus according to the invention is a regeneration method for a filtration apparatus that has a filter layer formed by filling a solid filter material formed with a protrusion on a surface, and passes water to be treated containing suspended matters through the filter layer to perform filtration of the suspended matters. The regeneration method for a filtration apparatus includes a step of backwashing the filter layer by passing washing liquid through the filter layer in a direction opposite to a passing direction of the water to be treated such that the protrusion is retained on the surface of the solid filter material.

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 natural water treatment control apparatus (190) controls a treatment device configured to perform treatment used to contribute to purification of drawn natural water. The natural water treatment control apparatus (190) includes: a tide information acquiring unit (191) configured to acquire tide information serving as information associated with tides of a body of water from which the natural water is drawn; and a treatment mode determining unit (193) configured to determine a treatment mode of the treatment device on the basis of the tide information.

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: A reverse osmosis membrane filtering device includes: a water-collecting member including at least one water collecting pipe, and having a plurality of sections each of which has a plurality of water collecting apertures: at least one filter assembly disposed around the plurality of sections, the at least one filter assembly including a filter member including a reverse osmosis membrane; at least one insertion tube disposed inside the water-collecting member and defining a plurality of permeate-water channels corresponding to the plurality of sections inside the water-collecting member in cooperation with at least one seal member; and a pressure adjusting device configured to increase a pressure of at least one of the plurality of permeate-water channels to a pressure higher than that of another one of the plurality of permeate-water channels.

Abstract: A biofilm filter device in which a biofilm formed on a filter medium layer removes impurities mixed in a target liquid flowing from an upstream side so as to discharge a filtered liquid from a downstream side. The biofilm filter device includes a wash water supply unit that supplies wash water from the downstream side of the filter medium layer, and a control unit that controls a flow speed of the wash water supplied by the wash water supply unit. After the control unit supplies the wash water at a first flow speed which fluidizes only a prescribed range layer on the upstream side of the filter medium layer, the control unit supplies the wash water at a second flow speed which does not fluidize the whole filter medium layer.