|
These are inorganic ions
dissolved in the feed-water and removed through the various
desalting processes. These ions include such ions as Na+, CA++, K+,
Mg++, Br-, Cl-, NO3-, SO4=, and PO4-3. Ion chromatography is the
only suitable method for low level analysis of these ions. Anions
and cations are normally analyzed as a part of an ion scan.
Heavy Metals
Heavy metals such as Fe, Cu, Ni, Zn, and Co are the most frequently
analyzed in purified water. However, Aluminum analysis is gaining
popularity as many cases of Reverse Osmosis membrane fouling are
being ascribed to this city water treatment chemical. Ion
chromatography or graphite furnace atomic absorption spectroscopy
are the methods of choice. AA spectroscopy, although quite
sensitive, is subject to a fair amount of background contamination.
ICP-mass spectrometry has gain favor in the past few years but is
subject to interferences also. Its’ major utility is in determining
cationic contaminants in process chemicals and waste streams.
|
Contaminant |
Problem |
Cause |
Possible Cure |
|
Ions |
high levels |
flow rates too high |
reduce flow
new
resin |
|
Metals |
high levels |
flow meters
Housings |
remove
reduce
ozone
reduce
UV's |
|
|
