Brown and Caldwell Home Page
Technical Papers RECENT PAPERS    ALL PAPERS

Brown and Caldwell engineers and scientists are technical and thought leaders in the environmental sector. Meet the people who have been advancing innovation for more than 70 years.
Author      Title/Abstract      


Gas Transfer from Air Diffusers
Author: Erica L. Schierholz, John S. Gulliver, Steven C. Wilhelms, Heather E. Henneman
Date: 3/106
Paper published as part of a Masters program.

The bubble and surface volumetric mass transfer coefficients for oxygen, kLab and kLas, are separately determined for 179 aeration tests, with diffuser depths ranging from 225 to 32m, using the DeMoyer et al. (2003. Impact of bubble and free surface oxygen transfer on diffused aeration systems, Water Res 37, 1890-1904) mass transfer model. Two empirical characterization equations are developed for kLab and kLas, correlating the coefficients to air flow, Qa, diffuser depth, hd, cross-sectional area, Acs, and volumne, V. The characterization equations indicate that the bubble transfer coefficient, kLab, increases with increasing gas flow rate and depth, and decreases with increasing water volume. For fine bubble diffusers, kLab is approximately six times greater than kLab for coarse bubble diffusers. The surface transfer coefficient kLAx, increases with increasing gas flow rate and diffuser depth. The characterization equations make it possible to predict the gas transfer that will occur across bubble interfaces and across the free surface with bubble plume at depths up to 32m and with variable air discharge in deep tanks and reservoirs.

This library contains published materials for which copyrights may be owned by entities other than Brown and Caldwell, but which are stored for limited uses by BC employees. Technical papers authored by BC employees generally may be printed and shared electronically with clients and prospective clients outside BC. Technical papers cannot be sold, and technical papers shared outside BC must have proper attribution of the original sponsoring organization or conference where the paper was presented. This attribution is embedded in each technical paper file when it is loaded into this library. Published articles from magazines or trade journals which are stored in this library are FOR INTERNAL USE ONLY and SHOULD NOT be distributed to clients or others outside BC, without express permission of the copyright owner. For questions regarding copyrights associated with any document in this library, or questions regarding copyrights in general, contact the Legal Department.