PARTICLE BEHAVIOR IN DEEP-BED FILTRATION .1. RIPENING AND BREAKTHROUGH

Laboratory-scale filtration experiments were conducted using sedimenta tion basin effluent from a local lime-softening water treatment plant. An electronic particle counter was used to observe changes in the par ticle size distribution of the filtrate as a function of filter depth and time under a variety of filter operating conditions. The experimen ts were conducted for an extended period (up to 48 h) to observe the e ffects of both ripening and breakthrough over the duration of a typica l water treatment plant filter cycle. The results indicate that ripeni ng and breakthrough are not distinct stages but occur simultaneously f or different-size particles. The effects of media size and filtration velocity were investigated, and simple normalizations were developed.