DETERMINATION OF PARTICLE COLLISION EFFICIENCIES FOR FLOCCULANT TRANSPORT MODELS

The object of this study is to investigate the data needs for accurate estimation of particle collision efficiencies (alpha). Batch floccula tion and vertical flocculent settling studies were conducted on aquati c sediment particles in the size range of 2-80 mu m in diameter. Dynam ic particle-size distribution data sets were generated using a 256-cat egory binary-collision-based flocculent settling model and subsequentl y compressed into 128, 64, 32, 16, 8, and 4 logarithmically varying pa rticle-diameter categories. A previously developed parameter-estimatio n framework was used to estimate alpha values from the compressed data sets. Variability in the alpha estimates indicates that it is not an artifact of the experimental data. The residual function value after 2 0 estimation iterations increased with the discretization levels, indi cating shallower residual function slopes. Parameter estimation accura cy was unaffected by the levels of data sparsity considered, Increased random noise resulted in consistently lower estimated collision effic iencies. Rate of convergence was unaffected by random noise but decrea sed with data sparsity levels. Particle water column residence times w ere significantly overestimated using four category distributions.