Authors: Edzwald James K
Publish Date: 1995/02/01
Volume: 31, Issue: 3-4, Pages: 1-23
Abstract
Principles of dissolved air flotation DAF discussed include bubble formation and size bubbleparticle interactions measures of supplied air and modeling of the reaction and clarification zones of the flotation tank Favorable flotation conditions for bubble attachment or adhesion to particles requires a reduction in the charge of particles and production of hydrophobic particles or hydrophobic spots on particle surfaces A conceptual model for the bubbleparticle reaction zone based on the single collector collision efficiency is summarized and discussed An alternative modeling approach is considered Clarification or separation zone modeling is based on particlebubble agglomerate rise velocities The application of DAF in drinking water treatment is addressed beginning with summaries of design and operating parameters for several countries DAF should not be considered as a separate process but integrated into the design and operation of the overall treatment plant This concept shows that flocculation ahead of DAF has different requirements regarding floc size and strength compared to sedimentation The efficiency of DAF in removing particles and reducing particle loads to filters needs to be integrated into DAF plant design The impact on filtration performance is illustrated Finally fundamental and applied research needs are addressed
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