Abstract: A water producing system is provided that produces fresh water by treating treatment target water A at a first semipermeable membrane treatment plant, that mixes concentrate resulted by the treatment carried out at the first semipermeable membrane treatment plant with treatment target water B, and that treats the mixed water at a second semipermeable membrane treatment plant to produce fresh water. A bypass line allows the treatment target water A to be mixed with the treatment target water B or the concentrate while bypassing the first semipermeable membrane treatment plant, so that the second semipermeable membrane treatment plant can operate even when any trouble occurs at the first semipermeable membrane treatment plant and treatment cannot be carried out thereby.

Abstract: A water producing system which is provided with a semi-permeable membrane treatment process A100 to produce membrane permeate A3 and concentrate A, a semi-permeable membrane treatment process 8200 which is equipped with a treatment target water B branching means for branching treatment target water B2 into two or more to produce a membrane B5 and concentrate B6, and a semi-permeable membrane treatment process C300 which is equipped with a first water mixing means for mixing one of the treatment target water B with at least part of the concentrate A, and subjects the mixed water to the semi-permeable membrane treatment to produce membrane permeate C7 and concentrate C8, thereby producing fresh water from a plurality of kinds of raw water which differ in osmotic pressure.

Abstract: A method of treating wastewater containing an organic compound includes feeding wastewater to an anoxic tank, adding compounds containing nitrogen and phosphorus components to wastewater, performing anaerobic treatment on wastewater, and discharging treated wastewater as pre-treated water; introducing pre-treated water into an anaerobic treatment tank, performing anaerobic treatment on pre-treated water, thereby decomposing the organic compound into organic compounds of smaller molecular size and a mixture gas containing methane and carbon dioxide, and discharging treated water as primary water; introducing primary water into an aerobic treatment tank, performing aerobic treatment on primary water, and discharging treated water through a solid-liquid separator as secondary water; and introducing at least a part of secondary water into a reverse osmosis membrane separation unit, and separating part of secondary water into RO permeated water and RO concentrated brine, wherein at least a part of RO concentrated

Abstract: A pure water production apparatus and method are provided that effectively use an isobaric type energy recovery unit that can efficiently recover energy against feed water variation. In a pure water producing method supplying and having a plurality of kinds of feed water with different water qualities permeated through a semi-permeable membrane to produce the pure water, a portion (referred to as first feed water) of the plurality of kinds of feed water supplied to a semi-permeable membrane unit comprising the semi-permeable membrane is boosted by utilizing an isobaric type energy recovery unit that recovers pressure energy of concentrate discharged from the semi-permeable membrane unit, the rest (referred to as second feed water) of the plurality of kinds of feed water is boosted by a high pressure pump, and the boosted first and second feed water are supplied together to the semi-permeable membrane unit.

Abstract: Provided is a fresh water production method applying a combined water-treatment technology employing a plurality of semi-permeable membrane units, the method enabling prevention of problems caused by growth of a biofilm and allowing effective use of an injected chemical agent and an injected neutralizing agent. The fresh-water production method produces fresh water by treatment of source water by a semi-permeable membrane treatment device, the concentrated water resulting from the treatment by the semi-permeable membrane treatment device is mixed with other source water, and the water mixture is treated by a second semi-permeable membrane treatment device. A first chemical agent is injected continuously or intermittently into the source water and a second chemical agent is injected continuously or intermittently into the source water.

Abstract: Provided is a method for producing fresh water, having a plurality of desalination processes in parallel where raw water or pre-treated raw water is treated by a first semi-permeable membrane unit, and the resulting permeate of which a pH is raised is treated in the second semi-permeable membrane unit, comprising: temporally, in part of desalination process A; lowering a pH of raw water or pre-treated water to be supplied to a first semi-permeable membrane unit A1 and to make a pH of the resulting permeate of the first semi-permeable membrane unit A1 lower than that of feed water of a second semi-permeable membrane unit B2 in desalination process B to be supplied to a second semi-permeable membrane unit A2; and mixing the permeate obtained from the second semi-permeable membrane unit A2 with the permeate obtained from the second semi-permeable membrane unit B2 in said desalination process B.

Abstract: A process for modifying a polymeric photoactive sulfone membrane includes placing the membrane into the presence of acrylic acid monomer dissolved in a solution and without sensitizer or free radical initiator and exposing the membrane to non-ionizing UV radiation for modifying the membrane by chemical grafting of the monomer at the surface of the membrane. The membrane can be polysulfone, polyethersulfone or polyarylsulfone. The radiation is selected to have an energy below that at which chain scission occurs and above that at which maximum grafting occurs. The process includes washing the modified membrane in a washing agent containing ethanol, glycol, ether, acid, hydrocarbon, or mixtures thereof, to wash homopolymer formed in the solution from the modified membrane, but preferably ethanol.

Abstract: A printing paper, especially a newsprint base paper, comprising: a base paper; and a coating layer for improving surface strength of the coated paper and releasing-property when two sheets of the coated paper are stacked, which coating layer is formed on the base paper by using a coating-transcription system such as a gate roll coating system, which coating layer comprises at least either a homopolymer polyacrylamide or a nonionic-copolymer polyacrylamide in a coating weight of from 0.01 g/m.sup.2 to 0.2 g/m.sup.2, wherein the homopolymer polytcrylamide and the nonionic-copolymer polyacrylamide have a weight average molecular weight ranging from 20,000 to 250,000, thereby improving not only surface strength but also releasing-property in a printing paper, especially in a newsprint paper having a basis weight less than 46 gm.sup.2.