A differential density soft sanitary tissue paper web having from about 2% to about 56.5% by weight of the differential density soft sanitary tissue paper web of a softwood pulp fiber mixture, and from about 43.5% to about 99.9% by weight of the dry fiber basis of the differential density soft sanitary tissue paper web of a hardwood pulp fiber mixture is provided. The softwood pulp fiber mixture has: 1) from about 0% to about 56.4% by weight of the dry fiber basis of softwood pulp fiber; 2) from about 0.05% to about 3.0% by weight of the dry fiber basis of strengthening additive. The hardwood pulp fiber mixture comprises: 1) from about 43.4% to about 99.4% by weight of the dry fiber basis of hardwood pulp fibers; and, 2) from about 0.05% to about 20.0% by weight of the dry fiber basis of cellulose nano-filaments.

A system and method of forming a molded pulp product that involves separately collecting, from a paper-making process, waste water containing short fibers at a first fiber consistency, waste water as dilution water containing fibers at a second fiber consistency that is lower than the first fiber consistency, and water containing long fibers, the long fibers having a length that is greater than a length of the short fibers, blending the waste water containing short fibers and the water containing long fibers to obtain a pulp slurry, and molding the pulp slurry into a molded pulp product at a pulp molding machine. In an embodiment, filtrate removed during the molding of the molded pulp product has a BOD measurement that is 95% less than a BOD measurement of the pulp slurry, where the BOD measurements are obtained using the EPA 405.1, SM5210B Test Method.

A system and method of forming a molded pulp product that involves separately collecting, from a paper-making process, waste water containing short fibers at a first fiber consistency, waste water as dilution water containing fibers at a second fiber consistency that is lower than the first fiber consistency, and water containing long fibers, the long fibers having a length that is greater than a length of the short fibers, blending the waste water containing short fibers and the water containing long fibers to obtain a pulp slurry, and molding the pulp slurry into a molded pulp product at a pulp molding machine. In an embodiment, filtrate removed during the molding of the molded pulp product has a BOD measurement that is 95% less than a BOD measurement of the pulp slurry, where the BOD measurements are obtained using the EPA 405.1, SM5210B Test Method.

A process for making an absorbent towel paper web is disclosed. The process provides the steps of: (a) providing a papermaking furnish, (b) forming a wet fibrous web having a differential density from the paper making furnish; and, (c) drying the differential density wet fibrous web to not more than about 10% by weight moisture. Step a) provides: i) from about 20.1% to about 99.9% by weight of a softwood pulp fiber mixture; and, ii) from greater than 0% to about 79.9% by weight of a hardwood pulp fiber mixture. Step i) provides u) from about 20.0% to about 99.8% by weight of softwood pulp fiber; and, v) from about 0.05% to about 5.0% by weight of strengthening additive. Step ii) provides w) from about 0.05% to about 79.4% by weight of hardwood pulp fibers; and, x) from about 0.05% to about 20.0% by weight of cellulose nano-filaments.

A process for making an absorbent towel paper web is disclosed. The process provides the steps of: (a) providing a papermaking furnish, (b) forming a wet fibrous web having a differential density from the paper making furnish; and, (c) drying the differential density wet fibrous web to not more than about 10% by weight moisture. Step a) provides: i) from about 20.1% to about 99.9% by weight of a softwood pulp fiber mixture; and, ii) from greater than 0% to about 79.9% by weight of a hardwood pulp fiber mixture. Step i) provides u) from about 20.0% to about 99.8% by weight of softwood pulp fiber; and, v) from about 0.05% to about 5.0% by weight of strengthening additive. Step ii) provides w) from about 0.05% to about 79.4% by weight of hardwood pulp fibers; and, x) from about 0.05% to about 20.0% by weight of cellulose nano-filaments.

The object of the invention is a filter paper characterized in that it includes between 70% and 100% by weight of cellulose fibers, wherein between 50% and 75% by weight of the fibers are long fibers, understanding by this fibers that have an average length greater than 2 mm, and between 25% and 50% by weight of the fibers are short fibers, understanding by this fibers that have an average length of less than 2 mm; between 0.1% and 5.0% by weight of sodium carboxymethyl cellulose; and wherein the weight of the filter paper per unit area is between 25 and 55 g/m.sup.2, measured according to UNE-EN ISO 536:2013 standard; the density thereof varies between 0.100 and 0.500 g/cm.sup.3, measured according to UNE-EN ISO 534:2012 standard in a single sheet; and the porosity of the filter paper is between 1500 and 8500 ml/min.Math.cm.sup.2.Math.kPa, measured according to UNE-EN ISO 2965:2019 standard. The paper filter including said filter paper is also an object of the invention.

The object of the invention is a filter paper characterized in that it includes between 70% and 100% by weight of cellulose fibers, wherein between 50% and 75% by weight of the fibers are long fibers, understanding by this fibers that have an average length greater than 2 mm, and between 25% and 50% by weight of the fibers are short fibers, understanding by this fibers that have an average length of less than 2 mm; between 0.1% and 5.0% by weight of sodium carboxymethyl cellulose; and wherein the weight of the filter paper per unit area is between 25 and 55 g/m.sup.2, measured according to UNE-EN ISO 536:2013 standard; the density thereof varies between 0.100 and 0.500 g/cm.sup.3, measured according to UNE-EN ISO 534:2012 standard in a single sheet; and the porosity of the filter paper is between 1500 and 8500 ml/min.Math.cm.sup.2.Math.kPa, measured according to UNE-EN ISO 2965:2019 standard. The paper filter including said filter paper is also an object of the invention.

A system and method of forming a molded pulp product that involves separately collecting, from a paper-making process, waste water containing short fibers at a first fiber consistency, waste water as dilution water containing fibers at a second fiber consistency that is lower than the first fiber consistency, and water containing long fibers, the long fibers having a length that is greater than a length of the short fibers, blending the waste water containing short fibers and the water containing long fibers to obtain a pulp slurry, and molding the pulp slurry into a molded pulp product at a pulp molding machine. In an embodiment, filtrate removed during the molding of the molded pulp product has a BOD measurement that is 95% less than a BOD measurement of the pulp slurry, where the BOD measurements are obtained using the EPA 405.1, SM5210B Test Method.

A system and method of forming a molded pulp product that involves separately collecting, from a paper-making process, waste water containing short fibers at a first fiber consistency, waste water as dilution water containing fibers at a second fiber consistency that is lower than the first fiber consistency, and water containing long fibers, the long fibers having a length that is greater than a length of the short fibers, blending the waste water containing short fibers and the water containing long fibers to obtain a pulp slurry, and molding the pulp slurry into a molded pulp product at a pulp molding machine. In an embodiment, filtrate removed during the molding of the molded pulp product has a BOD measurement that is 95% less than a BOD measurement of the pulp slurry, where the BOD measurements are obtained using the EPA 405.1, SM5210B Test Method.

A process for making absorbent towel paper webs is provided. The process comprises the steps of (a) providing a papermaking furnish having from about 45% to about 90% by weight of the dry fiber basis of the tissue towel paper web of a refined softwood pulp fiber mixture having from about 20.0% to about 88.5% by weight of softwood pulp fiber and from about 0.05% to about 5.0% by weight of strengthening additive and from about 10% to about 55% by weight of the dry fiber basis of the absorbent towel paper web of a hardwood pulp fiber mixture having from about 9.9% to about 54.9% by weight of hardwood pulp fibers and from about 0.05% to about 20.0% by weight cellulose nanofilaments; (b) forming a wet fibrous web from the paper making furnish; and, (c) drying the web until the web contains not more than about 10% by weight moisture.