The present description relates to a method for preparing a biocide enriched in oxygen-centred free radicals through UV radiation, a biocide enriched in oxygen- centred free radicals thus obtained, a method for sterilizing waters, a method for controlling the colonisation of micro-organisms in treated waters, as well as a method for controlling and/or for controlling and preventing the colonisation on the surfaces of submerged structures by aquatic filtering organisms that use said biocide enriched in oxygen-centred free radicals and plants suitable for implementing said methods.
