Method of treating surfaces

A method of treating at least one surface, comprising a step in which said at least one surface is contacted with an aqueous solution obtained by mixing in water an aqueous formulation comprising at least one biosurfactant and at least one organic acid, wherein the weight ratio between said at least one biosurfactant and said at least one organic acid is between 1:1000 and 10:1, in an amount such that said aqueous solution comprises said at least one biosurfactant in an amount between 0.0001 and 10% by weight and said at least one organic acid in an amount between 0.001 and 10% by weight;

• said at least one biosurfactant being selected from glycolipids, lipopeptides, lipoproteins, phospholipids and polymeric biosurfactants, from the group consisting of sophorolipids, rhamnolipids, trehalolipids, cellobiose lipids, surfactin, viscosin, lichenysin, iturin, fengycin, emulsan, biodispersan, alasan, liposan;
• said at least one organic acid being selected from citric acid, lactic acid, acetic acid, malic acid, maleic acid, formic acid, caprylic acid, methanesulfonic acid, tartaric acid, succinic acid, and polyaspartic acid;
• wherein said at least one surface is the internal surface of a plant fed with water from a water distribution system;
• wherein said method comprises a step of preventing formation of biofilm on said internal surface or of disintegrating the biofilm present on said internal surface, said step being a cleansing step;
• wherein said cleansing step comprises circulating said aqueous solution inside the plant, in contact with said at least one surface;
• and
• wherein said plant is an open system, wherein water coming from said water distribution system flow through the plant and then flows out from the plane without recirculating inside the plant.