Abstract: The invention relates to a method for increasing the benefit from starch in pulped, preferably repulped cellulosic material at paper or paperboard manufacturing comprising the steps of (a) pulping a cellulosic material containing a starch; (b) treating the cellulosic material containing the starch with one or more biocides, preferably in the thick stock area; and (h) adding an ionic polymer and preferably, an auxiliary ionic polymer to the cellulosic material; wherein the ionic polymer and the optionally added auxiliary ionic polymer preferably have a different average molecular weight and preferably a different ionicity, wherein the ionicity is the molar content of ionic monomer units relative to the total amount of monomer units.

Abstract: According to the invention, the content of peracid, in the presence of hydrogen peroxide, in a solution 2 in which the molar ratio between the concentration of hydrogen peroxide and the concentration of peracid is not higher than 100, is adjusted by means of a process according to which it is drawn by means of a pump 3 into the suction circuits of two pumps 5, 6 which operate at the same flow rate and may draw simultaneously a dilution and/or pH control liquid 9, pump 5 feeding the reference vat 7 of a two-beam photometer and pump 6 feeding its measuring vat 8, and the flow rates of the pumps 3, 5, 6 being adjusted so that the concentration of peracid in the measuring flow 10 is lower than about 100 ppm by weight, an excess of iodide 11 is added to the measuring flow 10 which exits from the pump 6 by means of a pump 13, a measuring unit 14 to which are connected the cells of the photometer compares the intensity of the iodine color formed in the measuring vat 8 to the reference in the reference vat 7 and tran

Abstract: The content of peracid, in the presence of hydrogen peroxide,in a solution 2 in which the molar ratio between the concentration of hydrogen peroxide and the concentration of peracid is not higher than 100, is adjusted by means of a process according to which the solution is drawn by a pump 3 into the suction circuits of two pumps 5, 6, which operate at the same flow rate and may draw simultaneously a dilution and /or pH control liquid 9. Pump 5 feeds the reference vat 7 of a two-beam photometer and pump 6 feeds the measuring vat 8, and the flow rates of the pumps 3, 5 and 6 are adjusted so that the concentration of peracid in the measuring flow 10 is lower than about 100 ppm by weight. An excess of iodide 11 is added to the measuring flow 10 which exits from the pump 6 by a pump 13 and measuring unit 14, to which are connected the cells of the photometer.