AWWA JAW10213

This paper presents a method for evaluating the various modes involved in particle removal from water by means of deep-bed filtration. Based on backwashing kinetics, this method takes into account the mechanisms associated with particle attachment (with and without alum treatment), particle agglomeration, and particle detachment. Experiments consisted of tests carried out on filter beds of sand, glass, and anthracite. Three filter grain sizes and two filtration rates were used. Several alum doses were added to a kaolinite suspension to produce suspended particles with different sizes and zeta potentials. Data indicate that the attachment force acting during formation of an agglomerate depends on size rather than zeta potential. Includes 6 references, tables, figures.