The PRO2 air membrane tube diffusers in this product series are high quality products from the NORRES stable, being mainly used for intermittent, compressed air aeration, nitrification and denitrification. Note that the membrane material exhibits very good resistance to municipal wastewater, in accordance to the latest version of the DWA-M advisory leaflet. Last but not least, if you have any questions about this product or if you are seeking the advice of a professional, you should contact NORRES.