Improved filtering medium and use of the said filtering medium for pollution removal from lagoons

摘要

Filtering medium based on activated carbon, characterized in that it comprises three superposed layers, respectively an inner layer and two top and bottom outer layers, the inner layer consisting of 80 to 95% by dry weight of activated carbon, the balance for 100% consisting of organic and/or inorganic chemical fibres, the bottom layer comprising at least 30% by dry weight of organic chemical fibres having OH functional groups and optionally inorganic fibres, the possible balance for 100% consisting, where appropriate, of activated carbon and/or of a material having a density below 0.9, all or some of the OH functional groups having reacted with a grafting reagent RX, where R is a suitable hydrophobic group in order to be able to be in the liquid state at a temperature of at least 200°C at atmospheric pressure and in order to be able to react on the OH functional groups at least under certain reaction conditions, while producing covalent grafting of hydrophobic groups R onto the OH functional groups with formation of a volatile compound HX under the reaction conditions, the top layer comprising from 5 to 25% by dry weight of activated carbon, the balance for 100% consisting of organic and/or inorganic chemical fibres.