A method is disclosed for treating aqueous feed by dissolved gas flotation. The aqueous feed originates from industrial processing of fibrous material, where the aqueous feed includes an aqueous phase and solid particulate material suspended in the aqueous phase. The method includes bringing a flocculant in contact with the aqueous feed, flocculating suspended solid particulate material into flocs and contacting formed flocs with gas bubbles and inducing their flotation in a flotation basin. The flocculant includes a polymer composition having a charge density of at the most 1.7 meq/g dry and the polymer composition includes a cationic synthetic first polymer having a charge density at least 1.0 meq/g dry at pH 2.8, and at least one second polymer obtained by polymerization of (meth)acrylamide, the second polymer being polymerized in presence of the cationic first polymer, where the first polymer has a higher charge density than the second polymer.

The purpose of the present invention is to provide a method which is for producing pulp fibers for cellulose nanofiberization from pulp fibers of used sanitary products, and which can produce pulp fibers for cellulose nanofiberization that have low lignin content and a low distribution thereof and that have excellent cellulose nanofiberization properties. This method is described below. The method is characterized by involving: a step for supplying, from a mixed solution supply port (32) to a treatment tank (31), a mixed solution (51) which contains superabsorbent polymers and pulp fibers derived from used sanitary products; a step for supplying an ozone-containing gas (53) from an ozone-containing gas supply port (43) to a treatment solution (52) inside of the treatment tank (31); a step in which, by raising the ozone-containing gas (53) while lowering the superabsorbent polymers and pulp fibers in the treatment tank (31), the ozone-containing gas (53) is brought into contact with the superabsorbent polymers and the pulp fibers, and pulp fibers for cellulose nanofiberization are formed from the pulp fibers; and a step for discharging the treatment solution (52) from a treatment solution discharge port (33), wherein the pulp fibers for cellulose nanofiberization have a lignin content of less than or equal to 0.1 mass %.

The purpose of the present invention is to provide a method which is for producing pulp fibers for cellulose nanofiberization from pulp fibers of used sanitary products, and which can produce pulp fibers for cellulose nanofiberization that have low lignin content and a low distribution thereof and that have excellent cellulose nanofiberization properties. This method is described below. The method is characterized by involving: a step for supplying, from a mixed solution supply port (32) to a treatment tank (31), a mixed solution (51) which contains superabsorbent polymers and pulp fibers derived from used sanitary products; a step for supplying an ozone-containing gas (53) from an ozone-containing gas supply port (43) to a treatment solution (52) inside of the treatment tank (31); a step in which, by raising the ozone-containing gas (53) while lowering the superabsorbent polymers and pulp fibers in the treatment tank (31), the ozone-containing gas (53) is brought into contact with the superabsorbent polymers and the pulp fibers, and pulp fibers for cellulose nanofiberization are formed from the pulp fibers; and a step for discharging the treatment solution (52) from a treatment solution discharge port (33), wherein the pulp fibers for cellulose nanofiberization have a lignin content of less than or equal to 0.1 mass %.

The present invention relates generally to the field of waste processing. The method comprises separating waste into at least two parts, comprising: (i) mainly food waste (fines) and (ii) mainly paper and other recyclable material (overs). The overs are pulped and washed to obtain a cellulose-rich biomass and the fines are optionally processed separately to recover a cellulose-rich biomass and the cellulose-rich biomass from both the fines and the overs may be combined.

The present invention relates generally to the field of waste processing. The method comprises separating waste into at least two parts, comprising: (i) mainly food waste (fines) and (ii) mainly paper and other recyclable material (overs). The overs are pulped and washed to obtain a cellulose-rich biomass and the fines are optionally processed separately to recover a cellulose-rich biomass and the cellulose-rich biomass from both the fines and the overs may be combined.

The present invention provides a novel method and composition for enhancing the efficiency of starch adsorption (i.e., starch trapping) from starch-containing furnishes comprising high content of recycled fibers for use in paper making processes such as pulp, paper, or board production. A novel polymer coagulation system is disclosed in which two quick inversion cationic emulsion polymers (starch trapping polymers A and B) are co-mixed at optimal blend ratios to meet specific recycled fiber and process water requirements for different recycled fiber plants and added to furnishes prior to formation of paper or board in a paper machine. Co-mixed solutions of starch trapping polymers A and B provide synergistic enhancements in (i) starch trapping efficiency and (ii) starch retention in the produced paper or board over equivalent dosage levels of singly administered polymer A, polymer B, or conventional starch trapping products, without over-flocculation or formation of stickies.

A method for manufacturing bleached pulp from a feedstock that includes recycled paper. The method includes steps of: (1) impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1; (2) cooking the impregnated material to remove at least a portion of the lignin within the impregnated material, thereby yielding a cooked pulp; and (3) bleaching the cooked pulp.

A disperser apparatus includes: a first disperser assembly configured to rotate around an axis; and a second disperser assembly facing the first disperser assembly. The first and second disperser assemblies each have a plurality of disperser-refiner plate segments annularly arranged. Each of the disperser-refiner plate segments includes a substrate having teeth extending from the substrate and arranged in rows disposed at radial intervals defining a dispersion section. Each tooth has a tooth height; and walls; and edges at junctions of adjacent walls. Each of the disperser-refiner plate segments further includes a refining section of refiner bars extending from the substrate, wherein adjacent refiner bars and the substrate define a groove between the adjacent refiner bars; and a plurality transition bars disposed between radially outermost teeth and the refining section.

A disperser apparatus includes: a first disperser assembly configured to rotate around an axis; and a second disperser assembly facing the first disperser assembly. The first and second disperser assemblies each have a plurality of disperser-refiner plate segments annularly arranged. Each of the disperser-refiner plate segments includes a substrate having teeth extending from the substrate and arranged in rows disposed at radial intervals defining a dispersion section. Each tooth has a tooth height; and walls; and edges at junctions of adjacent walls. Each of the disperser-refiner plate segments further includes a refining section of refiner bars extending from the substrate, wherein adjacent refiner bars and the substrate define a groove between the adjacent refiner bars; and a plurality transition bars disposed between radially outermost teeth and the refining section.

The present invention aims to provide a technique for easily and rapidly sorting printed materials suitable as raw materials of recycled paper.

Printed materials that are hard to recycle as waste paper can be identified by irradiating the surface of the printed materials with light and measuring the reflected light. Specifically, good quality recycled paper can be made efficiently from printed materials by removing printed materials having an absorption band around 1720 cm.sup.−1, around 1260 cm.sup.−1, around 1160 cm.sup.−1, or around 700 cm.sup.−1 from waste paper raw materials when the printed materials are irradiated with light on their surface.