Particle size distributions in treatment processes: Theory and practice

The removal of particles from water and wastewater streams is essential and is usually accomplished through flocculation, sedimentation, and filtration. Understanding particle removal requires understanding of particle heterodispersity, especially with respect to size. A joint mathematical and experimental approach to studying changes in size distributions in these processes has proven quite insightful. Recommendations for analysts and manufacturers of particle size distribution analyzers based on mathematical principles are elucidated. Flocculation modelling is quite advanced and can be used predictively under certain well defined conditions, but a full description of changes in the size distribution is not available for all conditions encountered. Insights from flocculation modelling in the last ten years might make significant design and operational differences in the next ten years. Filtration modelling is not as advanced, inasmuch as filtration is a far more complex treatment process, but size distribution measurements have increased understanding enormously, and modelling has enabled design and operational changes in common practice to be understood. (C) 1997 IAWQ. Published by Elsevier Science Ltd.