Reverse osmosis (RO) is widely applied in the industry, to remove salts and other substances from process water. Bacterial growth on RO membranes can greatly reduce the efficiency of this process, thus large amounts of chemicals (usually known as “biocides”) are dosed in the water, to prevent the proliferation of bacteria. Many biocides are oxidizers, and their contact with RO membranes shall be avoided. For this reason, a tradeoff has to be achieved between the efficiency of the chemical treatment and the prevention of damages caused by such substances. A new application case is available, illustrating how ALVIM Biofilm Sensors allow to detect bacterial growth in membrane processes, to check and optimize chemical treatments.