The invention relates to the use of a composition for the antimicrobial and/or antioxidative treatment of biofilms in water-containing liquids, comprising: (a) a micelle-forming solubilizate which comprises at least one plant extract, at least one emulsifier with an HLB number of 8 to 18, and water, and (b) at least one biodegradable antimicrobial agent selected from the group consisting of peroxides, including peroxycarboxylic acids and H
