This study was undertaken because the literature
on enhanced softening, specifically with
respect to the role of magnesium in removing
natural organic matter (NOM), has been limited.
In evaluating the fundamental chemistry of precipitate
characteristics and their effect on NOM
removal, this research showed that NOM removal
before magnesium hydroxide precipitation occurs
from adsorption onto calcium carbonate (and
mixed magnesium-calcium carbonate) precipitates
as they form and possibly also through direct
precipitations as a magnesium fulvate or humate.
The authors identify three potential strategies
that softening plants can use to enhance NOM
removal and reduce disinfection byproduct formation.
Some facilities might be able to operate at
a slightly higher lime dose, avoiding magnesium
hydroxide precipitation while achieving slightly
greater removal of total organic carbon. Depending
on source water characteristics, plants could
enhance NOM removal by adding magnesium. If
NOM removal is to be maximized, soda ash (if
required) should be added in the second stage of a
two-stage softening process. Includes 37 references, tables, figures.
| Edition : | Vol. 101 - No. 4 |
| File Size : | 1
file
, 750 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 04/01/2009 |
