IWRA Proceedings

AbstractTraditionally, water treatment plant includes general processes such as: coagulation, flocculation, sedimentation, filtration and disinfection. Optimal choice of operating parameters for each of these processes is the most challenging task of any design. Unfortunately, all of the processes are very dynamic and strongly dependent on fluctuable quality of raw water. In consequence, optimal working parameters guaranteeing relatively low cost and high removal efficiency also should be dynamically adjusted in time. Complex mathematical models indicate the dependence of the processes on many parameters. Particle size distribution is one of the most important for all of them. Significant development of the particle size distribution (PSD) measuring methods was observed during last years. Simple and quick “on-line” PSD measurement is possible today. Particle size distribution enables more detailed water treatment processes analysis than still commonly used turbidity. The research was carried out in a treatment plant supplied with water from the Dlubnia river, which is one of the several supplying Krakow. Flocculation, sedimentation and filtration were analyzed based on particle size distribution curves. Refractive indexes were adequately selected. After flocculation, the concentration of particles between 1 and 30 microns increased in comparison with other fractions. After sedimentation particles bigger than 10 microns relatively decreased, and particles smaller than one micron and bigger than 100 microns relatively increased. During depth filtration volume of particles bigger than one micron were removed relatively better than the rest of the particles. The total volumetric suspension concentration slightly increased after flocculation and visibly decreased after sedimentation and then significantly decreased after filtration. A theoretical interpretation of the results was proposed.