Characterizing the Spatial Variation in Particle Aggregation Due

A study was performed to investigate the impact of turbulent heterogeneity on aggregation and breakup in a flocculation reactor. The influence of the average characteristic velocity gradient (G), particle concentration, and coagulation mechanism on the flocculation performance was also investigated. Experiments were performed in a bench-scale reactor with a low-shear axial-flow impeller using a photometric dispersion analyzer (PDA) to examine the state of aggregation. Results indicated that floc growth increased while the floc size and variance in the floc size distribution decreased as G increased. In addition, floc growth, size, and floc size variance increased when the particle concentration of the water was increased and when moving from a charge neutralization mechanism to a sweep floc mechanism. Lastly, floc growth, size, and variance were found to vary spatially at low G values in the reactor with floc size and growth larger in the bulk region and the variance larger in the impeller discharge region. CHARACTERIZING THE SPATIAL VARIATION IN PARTICLE AGGREGATION DUE TO HETEROGENEOUS TURBULENCE IN A FLOCCULATION REACTOR by DANIEL CORY HOPKINS A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science CIVIL ENGINEERING Raleigh 2002