Liquid acrolein, whose hazardous properties make handling difficult, is used to dose aqueous systems with acrolein in a biocidally effective concentration. Disclosed are agents which increase the ease and safety of acrolein handling and which are characterized by a content of 30 to 95% by weight acrolein and 5 to 70% by weight inorganic carrier materials. Silicas are the preferred carrier materials. The powdery or highly viscous mixture of substances will preferably exist in molded form and is additionally provided with a cladding that is impermeable to acrolein vapor. In dosing the aqueous systems, the agents are introduced directly in the water whereupon the acrolein is released.
Stretches of flowing water are doped with acrolein for the purpose of preventing excessive growth of plants and algae. In order to avoid transport of acrolein, acrolein is produced at the site where it is required by deacetalation of an acrolein acetal in the presence of an aqueous mineral acid. No electrical energy is necessary for this process. An acrolein acetal and an aqueous mineral acid solution are delivered from compression-proof storage tanks into a mixing chamber by the application of pressure from a pressure cylinder. The mixture is passed through a deacetalation reactor unit which includes a tubular reactor part and a container-shaped reactor part.
