Abstract: A silica fouling inhibition method for a reverse osmosis membrane system is provided, in which an acrylic acid-based polymer and/or a maleic acid-based polymer; and a combined chlorine-based oxidizing agent and/or a combined bromine-based oxidizing agent are allowed to be present in water to be treated. A silica fouling inhibitor for a reverse osmosis membrane system is provided, the silica fouling inhibitor includes: a copolymer of acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid and/or a terpolymer of acrylic acid, acrylamide methylpropanesulfonic acid, and N-substituted acrylamide; and a combined chlorine-based oxidizing agent and/or a combined bromine-based oxidizing agent.

Abstract: A method for preventing microorganism fouling in a water system containing a reducing agent, said microorganism fouling prevention method for a water system being characterized by adding a stabilized chlorine-based oxidizing agent composed of a chlorine-based oxidizing agent and a sulfamic acid compound, with the ratio of the sulfamic acid compound relative to 1 mol effective chlorine of the chlorine-based oxidizing agent being 1-1.5 mol, and/or a stabilized bromine-based oxidizing agent composed of a bromine-based oxidizing agent and a sulfamic acid compound, with the ratio of the sulfamic acid compound relative to 1 mol effective chlorine conversion amount of the bromine-based oxidizing agent being 1-1.5 mol, to the water system, such that the addition concentration of the stabilized chlorine-based oxidizing agent and/or the stabilized bromine-based oxidizing agent relative to the reducing agent concentration in the water system is 2.5 times or more by molar ratio.

Abstract: An antibody separation method including a step of applying a solution containing an antibody to a column filled with an antibody adsorption material containing an insoluble porous carrier and an Fc-binding protein immobilized on the carrier and adsorbing the antibody onto the antibody adsorption material; and a step of applying a buffer solution to the column and eluting the antibody adsorbed onto the antibody adsorption material with a pH gradient, wherein the pH gradient is a step gradient in which a pH of the buffer solution is lowered in steps, and wherein the magnitude of pH decrease is 0.1 or more and less than 1.