A recycled pulp that is reusable sanitary products is efficiently manufactured by recovering pulp fiber from used sanitary products containing the pulp fiber and a polymer absorbent. The method of the present invention comprises: a step applying a mechanical force to the used sanitary products in an aqueous solution containing a polyvalent metal ion or an acidic aqueous solution with a pH of 2.5 or lower and thus degrading the used sanitary products into the pulp fiber and other materials; a step separating the pulp fiber from the mixture of the pulp fiber and other materials that has been formed in the degradation step; and a step treating the pulp fiber thus separated with an ozone-containing aqueous solution with a pH of 2.5 or lower.

A containerboard can include a plurality of first fibers having a length weighted average fiber length that is greater than 0.5 mm, a plurality of second fibers having a length weighted average fiber length that is less than 2.0 mm, and a plurality of SEPF. The fiber length of the first fibers may be greater than the fiber length of the second fibers. The SEPF may include an average hydrodynamic specific surface area of at least 4.5 square meters per gram (m.sup.2/g) and comprise less than 10%, by weight, of the containerboard.

The presently disclosed subject matter relates to an industrial system for processing various plant materials to produce marketable materials. Particularly, the system integrates subcritical water extraction technology and includes a pre-processing module and a two-stage extractor (processing module) with constant control of temperature, pressure, and/or residence time. In some embodiments, the final product of the disclosed system can include feedstock constituents for biofuel production (sugars and/or oil), biochar, raw materials for various industries (such as pulp for manufacturing paper or cellulose for use in various industries). The disclosed system can be modular or non-modular, stationary or mobile, and can include prefabricated elements with programmed automatic or manual operation so that it can be easily moved and/or assembled on site.

The presently disclosed subject matter relates to an industrial system for processing various plant materials to produce marketable materials. Particularly, the system integrates subcritical water extraction technology and includes a pre-processing module and a two-stage extractor (processing module) with constant control of temperature, pressure, and/or residence time. In some embodiments, the final product of the disclosed system can include feedstock constituents for biofuel production (sugars and/or oil), biochar, raw materials for various industries (such as pulp for manufacturing paper or cellulose for use in various industries). The disclosed system can be modular or non-modular, stationary or mobile, and can include prefabricated elements with programmed automatic or manual operation so that it can be easily moved and/or assembled on site.

A bale of sheets made of waste/recycle cellulose fibers and cellulose ester (CE) staple fibers can be fed to a hydropulper. The CE staple fibers have: i. a denier per filament (DPF) of less than 3, or ii. a cut length of less than 6 mm, or iii. crimping, or iv. a combination of any two or more of (i)-(iii). The bales can be fed and dropped in as entire bales to a hydropulper, or a blend tank directly or indirectly in fluid communication with a hydropulper, using the same feed system employed for feeding cellulose to the hydopulper and avoiding having to defiberize by pulling or drawing fibers from a box container into a hydropulper. The waste/recycle cellulose fibers and CE staple fibers can be co-refined prior to making the bale of sheets.

A disperser-refiner plate segment includes a refining section disposed radially outward from a dispersion section. Teeth in the dispersion section have a height that exceeds a height of refining bars in the refining section.

A disperser-refiner plate segment includes a refining section disposed radially outward from a dispersion section. Teeth in the dispersion section have a height that exceeds a height of refining bars in the refining section.

Some variations provide a process for producing a nanocellulose material, comprising: providing a biomass feedstock comprising a bleached or unbleached pulp material; fractionating the feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material. The process is preferably co-located with, or adjacent to, a mill that generates the pulp material. There are several advantages of a bolt-on AVAP® nanocellulose plant to an existing pulp mill, as disclosed herein.

Some variations provide a process for producing a nanocellulose material, comprising: providing a biomass feedstock comprising a bleached or unbleached pulp material; fractionating the feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material. The process is preferably co-located with, or adjacent to, a mill that generates the pulp material. There are several advantages of a bolt-on AVAP® nanocellulose plant to an existing pulp mill, as disclosed herein.

Methods and systems of the present invention use mixed textile feedstock, which may include post-consumer waste garments, scrap fabric and/or other textile materials as a raw feed material to produce isolated cellulose and other isolated molecules having desirable properties that can be used and be used in the textile and apparel industries, and in other industries. A multi-stage process is provided, in which mixed textile feed material is subjected to one or more pretreatment stages, followed by at least two pulping treatments for isolating cellulose molecules and other molecular constituents, such as polyester. The isolated cellulose and polyester molecules may be used in a variety of downstream applications. In one application, isolated cellulose and polyester molecules are extruded to provide regenerated cellulose fibers and regenerated polyester fibers having desirable (and selectable) properties that are usable in various industrial applications, including textile production.