with lime pretreatment. Sulfuric acid should not be used
been added, the pH is often changed significantly. In
most cases, the pH must be returned to a neutral or a
for pH adjustment of systems where the resulting
increase in sulfate salts can cause scaling in the
slightly acid level. Adjustment chemicals to lower the
pH include carbon dioxide, sulfuric acid, and
desalination system. Fluoride removal will be hindered,
if the pH is reduced below 7.0.
hydrochloric acid. Carbon dioxide should not be used
c. Scale inhibition. The formation of scale
for pH adjustment of lime addition systems because of
the previously mentioned scaling problem associated
Source. American Institute of Chemical Engineers
Figure 5-2. Approximate concentration factor limits for calcium sulfate in sea water.