To provide a hollow fiber type semipermeable membrane which achieves both water permeability and salt rejection ability at high level, so as to conduct, with small membrane area, a water treatment utilizing concentration difference from liquid mixture of high concentration and high osmotic pressure. A hollow fiber type semipermeable membrane comprising cellulose acetate, characterized in that, between an aqueous solution of 25 C. having sodium chloride concentration of 35,000 mg/L and freshwater of 25 C. having sodium chloride concentration of 0 g/L at 0 MPa, the permeation flow rate flown from inner side to the outer side of the hollow fiber type semipermeable membrane is 60 to 180 L/m.sup.2/day, the outer diameter of the hollow fiber type semipermeable membrane is 100 to 350 m, the inner diameter thereof is 50 to 250 m and the hollow ratio thereof is 24 to 51%.

To provide a hollow fiber type semipermeable membrane which achieves both water permeability and salt rejection ability at high level, so as to conduct, with small membrane area, a water treatment utilizing concentration difference from liquid mixture of high concentration and high osmotic pressure. A hollow fiber type semipermeable membrane comprising cellulose acetate, characterized in that, between an aqueous solution of 25 C. having sodium chloride concentration of 35,000 mg/L and freshwater of 25 C. having sodium chloride concentration of 0 g/L at 0 MPa, the permeation flow rate flown from inner side to the outer side of the hollow fiber type semipermeable membrane is 60 to 180 L/m.sup.2/day, the outer diameter of the hollow fiber type semipermeable membrane is 100 to 350 m, the inner diameter thereof is 50 to 250 m and the hollow ratio thereof is 24 to 51%.

The disclosure pertains to sanitizing the permeate flow path of a reverse osmosis system. A method of sanitizing a filtration system is disclosed that can include injecting a biocide into a permeate compartment of an operating reverse osmosis system. The method can also include maintaining pressure in a concentrate compartment of the reverse osmosis system simultaneously while injecting the biocide.

The disclosure pertains to sanitizing the permeate flow path of a reverse osmosis system. A method of sanitizing a filtration system is disclosed that can include injecting a biocide into a permeate compartment of an operating reverse osmosis system. The method can also include maintaining pressure in a concentrate compartment of the reverse osmosis system simultaneously while injecting the biocide.

A method of measuring concentration of dissolved organic nitrogen in sewage. The method includes: filtering a sewage sample using a filter membrane; measuring the concentrations of total dissolved nitrogen (TDN), ammonia nitrogen (NH.sub.4.sup.+), and nitric nitrogen (NO.sub.3.sup.) in the sewage sample, respectively designated as C.sub.TDN(I), C.sub.NH4.sup.+.sub.(I) and C.sub.NO3.sup..sub.(I); calculating the ratios of (C.sub.NH4.sup.+.sub.(I)+C.sub.NO3.sup..sub.(I))/C.sub.TDN(I) and C.sub.NO3.sup..sub.(I)/C.sub.NH4.sup.+.sub.(I), and according to the ratios, calculating the concentration of dissolved organic nitrogen (DON) in the sewage sample.

A method of measuring concentration of dissolved organic nitrogen in sewage. The method includes: filtering a sewage sample using a filter membrane; measuring the concentrations of total dissolved nitrogen (TDN), ammonia nitrogen (NH.sub.4.sup.+), and nitric nitrogen (NO.sub.3.sup.) in the sewage sample, respectively designated as C.sub.TDN(I), C.sub.NH4.sup.+.sub.(I) and C.sub.NO3.sup..sub.(I); calculating the ratios of (C.sub.NH4.sup.+.sub.(I)+C.sub.NO3.sup..sub.(I))/C.sub.TDN(I) and C.sub.NO3.sup..sub.(I)/C.sub.NH4.sup.+.sub.(I), and according to the ratios, calculating the concentration of dissolved organic nitrogen (DON) in the sewage sample.

The present invention relates generally to compositions for use in biological and chemical separations, as well as other applications. More specifically, the present invention relates to hybrid felts fabricated from electrospun nanofibers with high permeance and high capacity. Such hybrid felts utilize derivatized cellulose, and at least one non-cellulose-based polymer that may be removed from the felt by subjecting it to moderately elevated temperatures and/or solvents capable of dissolving the non-cellulose-based polymer to leave behind a porous nanofiber felt having more uniform pore sizes and other enhanced properties when compared to single component nanofiber felts.

A process for preparing a composite membrane comprising the steps: a) applying a radiation-curable composition to a porous support; b) irradiating the composition present on the support, thereby forming a gutter layer of cured polymer; c) forming a discriminating layer on the gutter layer; and d) applying a radiation-curable composition to the discriminating layer and irradiating that composition, thereby forming a protective layer on the discriminating layer; wherein one or both of the radiation-curable compositions applied in steps a) and d) comprise a photo acid generator having an absorbency coefficient ? at 313 nm of more than 1?10.sup.4 mol.sup.?1*cm.sup.?1. Also claimed are composite membranes and gas separation cartridges comprising the membranes.

A hollow fiber type semipermeable membrane which achieves both water permeability and selectivity in high level and performs efficient treatment using small membrane area utilizing the concentration difference from high concentration liquid having high osmotic pressure. The hollow fiber type semipermeable membrane is characterized in that, when an aqueous solution of 25? C. having NaCl concentration of 35 g/L and pressure of 1.0 MPa is flown into an outer side of the hollow fiber type semipermeable membrane having length of about 70 cm while freshwater of 25? C. having NaCl concentration of 0 g/L is flown into an inner side of one open end of the hollow fiber type semipermeable membrane and discharged from another open end at 10 kPa or less, the permeation flow rate is 30 to 70 L/m.sup.2/day. An inner diameter thereof is 50 to 200 ?m; and the hollow ratio thereof is 24 to 42%.

A hollow fiber type semipermeable membrane which achieves both water permeability and selectivity in high level and performs efficient treatment using small membrane area utilizing the concentration difference from high concentration liquid having high osmotic pressure. The hollow fiber type semipermeable membrane is characterized in that, when an aqueous solution of 25? C. having NaCl concentration of 35 g/L and pressure of 1.0 MPa is flown into an outer side of the hollow fiber type semipermeable membrane having length of about 70 cm while freshwater of 25? C. having NaCl concentration of 0 g/L is flown into an inner side of one open end of the hollow fiber type semipermeable membrane and discharged from another open end at 10 kPa or less, the permeation flow rate is 30 to 70 L/m.sup.2/day. An inner diameter thereof is 50 to 200 ?m; and the hollow ratio thereof is 24 to 42%.