Contact

Prof. Dr.-Ing. Dr. h. c. Uwe Hampel

Head
Experimental Thermal Fluid Dynamics
u.hampel@hzdr.de
Phone: +49 351 260 2772

Efficient gas dispersion systems

The established technique of gas dispersions in municipal waste water treatment facilities are pressurized air diffusers with perforated flexible membranes that are mounted at the bottom of the basins. This commercial technique has a relatively low standard oxygen transfer efficiency (SOTE) in the order of 40-60 % (Wang et al. 2010), where the initial bubble size distribution, the gas bubble residence time and the gas hold up are the limiting factors. By the injection of submillimeter gas bubbles the oxygen mass transfer from the gas to the liquid phase and SOTE would be enhanced by the increased phase contact area and the extended bubble residence time. Moreover, the biological degradation process should be stabilized.

Results

Development and validation of novel gas dispersion systems for enhanced energy efficiency is the main goal of the project SEBAK (MKULNV, project number 17-04.02.01-9a/2014). Fundamental experiments are being conducted to study the generation process of gas bubbles at flexible and rigid orifices for different sparger plate materials. Moreover, continuous and dynamic flow regimes are investigated. Results of laboratory studies reveal that significantly smaller gas bubbles are generated by micro-perforated stainless steel plates compared to commercial rubber membrane spargers (Mohseni et al. 2017).

Gas bubble generation at a micro perforated stainless steel plate(left), Comparison of Sauter mean diameter of gas bubbles from stainless steel plate and commercial rubber membranes(right)

Concepts of gas dispersion systems are developed based on the established knowledge base. Experimental validation is performed in ad hoc laboratory setups and an especially designed pilot rig. An innovative stainless steel sparger developed by IWEB GmbH was tested and it is showing significantly higher efficiency compared to commercial rubber membrane spargers.

Experimental rig in the lab(left), Aerator efficiency of stainless steel spargers compared to commercial rubber membrane spargers measured in clean water(right)

Partners

IWEB Institut für Wasser & Energie Bochum GmbH
SOWAG Süd-Oberlausitzer Wasserversorgungs- und Abwasserentsorgungsgesellschaft mbH
Stadtentwässerung Dresden GmbH

Funded by

NRW Förderlogo

Literature

Wang, L. K., Shammas, N. K., Hung, Y.-T.
Advanced biological treatment processes
Springer Science & Business Media (2010)
Mohseni, E., Herrmann-Heber, R., Reinecke, S.F., Hampel, U.
Bubble Generation by Solid Membrane Spargers for Activated Sludge Wastewater Treatment Application
Proceedings of 9th Eastern European Young Water Professionals Conference IWA YWP, 24.-27. Mai 2017, Budapest, Ungarn (2017)