PARTICLE-SIZE DISTRIBUTIONS IN TREATMENT PROCESSES - THEORY AND PRACTICE

The removal of particles from water and wastewater streams is essentia l and is usually accomplished through flocculation, sedimentation, and filtration. Understanding particle removal requires understanding of particle heterodispersity, especially with respect to size. A joint ma thematical and experimental approach to studying changes in size distr ibutions in these processes has proven quite insightful. Recommendatio ns for analysts and manufacturers of particle size distribution analyz ers based on mathematical principles are elucidated. Flocculation mode lling is quite advanced and can be used predictively under certain wel l defined conditions, but a full description of changes in the size di stribution is not available for all conditions encountered. Insights f rom flocculation modelling in the last ten years might make significan t design and operational differences in the next ten years. Filtration modelling is not as advanced, inasmuch as filtration is a far more co mplex treatment process, but size distribution measurements have incre ased understanding enormously, and modelling has enabled design and op erational changes in common practice to be understood. (C) 1997 IAWQ. Published by Elsevier Science Ltd.