Time-Variations of Transfer Efficiency and Headloss for Fine-Pore Membrane Diffusers in Aeration Systems
Abstract:Fine-pore diffusers are the most common aeration systems in municipal wastewater treatment. Punched polymeric membranes are often used in fine-pore aeration due to their advantageous initial performance. These membranes are subject to fouling and scaling, resulting in increased headloss and reduced oxygen transfer efficiency, both contributing to increase plant energy costs. This paper describes and discusses the change in material properties for polymeric fine-pore diffusers, comparing new and used membranes. Three different diffuser technologies were tested and sample diffusers from two wastewater treatment facilities were analyzed. The polymeric membranes analyzed in this paper were composed of ethylene-propylene-diene (EPDM), polyurethane, and silicon. Transfer efficiency is consistently lower with longer times in operation, as older, dilated orifices produce larger bubbles, which are unfavorable to mass transfer. At the same time, headloss increases with time in operation, since membranes increase in rigidity and hardness, and fouling and scaling phenomena occur at the orifice opening. Evidence here reported shows the change in polymer properties and our laboratory test results correlate these changes with the decrease of oxygen transfer efficiency.
Document Type: Research Article
Publication date: October 1, 2007
More about this publication?
- Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed. WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access.
- Subscribe to this Title
- Membership Information
- About WEF Proceedings
- WEFTEC Conference Information
- ingentaconnect is not responsible for the content or availability of external websites