In most water treatment plants, coagulation involves precipitation, i.e., the formation of new
solids from added chemicals. These plants add iron or aluminum salts in the "sweep floc" regime
to form solid hydroxides, or they employ precipitative softening to form calcium carbonate (and,
perhaps, magnesium hydroxide). This precipitation is vital to the removal of dissolved
constituents (e.g., arsenic and natural organic matter by adsorption) and particles (including
microorganisms). Ultimate removal of these constituents relies primarily on the resultant particle
size distribution (PSD) fed to downstream particle removal processes (i.e., sedimentation or
flotation and granular media or membrane filtration). The current understanding of how
precipitation changes the PSD is only qualitative. The goal of this work is to create and
experimentally verify a mathematical model capable of quantitatively predicting how PSDs
change due to simultaneous precipitation and flocculation. Experiments are being performed
with calcium carbonate to emulate softening and aluminum hydroxide to emulate alum sweepfloc
coagulation. Includes 13 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 460 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 06/01/2006 |
