The study of physico-chemical characteristics of water and their
effect on the surrounding environment, are often treated as a special
case because the complexity of relations between ions.
These equilibria are unstable due to changes of temperature and
concentrations of dissolved gases (escape or dissolution), which
brings new reactions and consequences on the environment in contact
In particular, problems of treatment of aggressivity (water), of
inlay or corrosion, are generated by changes in physico-chemical
equilibria and bring technical problems for the collection,
conveyance and distribution of water.
Note: the study of these problems almost always leads us to what we
can call the "calcocarbonic equilibrium."
Fixed aggressiveness to equilibrium.
The target is to remove carbon dioxide (CO2) from
aggressive water, and if necessary increase the alkalinity (TAC) and
/ or Hardness (TH) of these so-called "aggressive" water.
For protection of piping distribution network, we seek to meet
following quality objectives:
- TAC (Alkalinity) neighbor TH calcium, with a minimum value of
about 8 °F (80 mg/L as CaCO3)
- pH slightly higher than the equilibrium pH
- pH 8.2 or less to maintain a water disinfecting power
In general, treatment should promote a neighbor TH /TAC, and an
index Larson less than 1 to limit corrosion of pipes.
Three types of treatment are possible:
* Reminder: aggressive CO2 (with respect to carbonates)
is the fraction of dissolved free CO2 in excess of
carbonate ion / bicarbonate [CO3] /
[HCO3] and CO2 which is in association
with balance of these ions.
Possibly >> see> this page (pdf
file) to the balance.
Aeration treatment (removal of carbon
Physical method, used only if CO 2 is high and for which amounts of
neutralizing reagents are prohibitive.
- runoff by waterfalls
- injecting air into the liquid mass
runoff or spray on materials in contact tower.
Reminder: only carbon dioxide decreases, this operation leaves TAC
(Alkalinity) and TH unchanged.
to the Hydro-Land website )
Treatment by neutralization.
A chemical process, which allows the CO2 removal per
neutralization with a basic reagent ( x-OH-).
Main simplified reaction: CO2 + x-OH-
>>> x (HCO3-)
Possible main practices:
Reagents which act only on the Hardness (not CO2
(use your browser)