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: To enable energy-saving operation and stable supply of permeate water while water quality level of the permeate water is satisfied during operation, clarified seawater sw subjected to pretreatment and stored in to-be-treated water tank 12 is supplied to reverse osmosis membrane module 14 via clarified seawater supply passage 16. Permeate water pw obtained by an earlier stage element of the reverse osmosis membrane elements 36 of the reverse osmosis membrane module 14 is sent to a subsequent process from permeate water sending passage 46, and permeate water pw obtained by the reverse osmosis membrane element 36 is circulated into the to-be-treated water tank 12 via permeate water circulation passage 48.

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 apparatus has a plurality of high pressure vessels 12a and 12b in parallel with each other with respect to introducing passage 18 of clarified seawater obtained by subjecting raw seawater to sterilization and removal of relatively large foreign substances. The high pressure vessels 12a and 12b have first-stage reverse osmosis membrane elements 14a and 14b, respectively. Concentrated seawater subjected to membrane separation in the high pressure vessels 12a and 12b flows into a high pressure vessel 16. In the high pressure vessel 16, a plurality of reverse osmosis membrane elements 42 are arranged in series. When a detected value obtained by a differential pressure meter 56a or 56b provided for the high pressure vessel 12a or 12b exceeds a threshold value, introduction of the clarified seawater is stopped, and the reverse osmosis membrane element is washed or replaced.

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 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: 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: A reverse osmosis membrane apparatus has a plurality of high pressure vessels 12a and 12b in parallel with each other with respect to introducing passage 18 of clarified seawater obtained by subjecting raw seawater to sterilization and removal of relatively large foreign substances. The high pressure vessels 12a and 12b have first-stage reverse osmosis membrane elements 14a and 14b, respectively. Concentrated seawater subjected to membrane separation in the high pressure vessels 12a and 12b flows into a high pressure vessel 16. In the high pressure vessel 16, a plurality of reverse osmosis membrane elements 42 are arranged in series. When a detected value obtained by a differential pressure meter 56a or 56b provided for the high pressure vessel 12a or 12b exceeds a threshold value, introduction of the clarified seawater is stopped, and the reverse osmosis membrane element is washed or replaced.

Abstract: To enable energy-saving operation and stable supply of permeate water while water quality level of the permeate water is satisfied during operation, clarified seawater sw subjected to pretreatment and stored in to-be-treated water tank 12 is supplied to reverse osmosis membrane module 14 via clarified seawater supply passage 16. Permeate water pw obtained by an earlier stage element of the reverse osmosis membrane elements 36 of the reverse osmosis membrane module 14 is sent to a subsequent process from permeate water sending passage 46, and permeate water pw obtained by the reverse osmosis membrane element 36 is circulated into the to-be-treated water tank 12 via permeate water circulation passage 48.

Abstract: A highly practical tube body for a pressure transducer is provided which has excellent pressure resistance, corrosion resistance, and tensile strength; which can be manufactured at low cost in comparison with cases of using stainless steel; and which makes it possible to keep inside diameter precision high. In this tube body for a pressure transducer, the pressure applied to the interior is varied periodically, and a seal layer (2) is provided to the internal peripheral surface of a tube body (1) made of a fiber-reinforced resin composed of fibers wound in layers.

Abstract: A highly practical tube body for a pressure transducer is provided which has excellent pressure resistance, corrosion resistance, and tensile strength; which can be manufactured at low cost in comparison with cases of using stainless steel; and which makes it possible to keep inside diameter precision high. In this tube body for a pressure transducer, the pressure applied to the interior is varied periodically, and a seal layer (2) is provided to the internal peripheral surface of a tube body (1) made of a fiber-reinforced resin composed of fibers wound in layers.