STANDARDS FOR POTABLE WATER :
Suspended
Solids < 500 ppm
Turbidity
< 10 ppm
B-Coli—NIL
M.P.N.
– one number in 100 ml
Hardness
<100 ppm="">100>
Chloride<250 ppm="<!--250--">250>
Iron
and Manganese < 0.3 ppm
PH=
6.5 to 8
Lead<
0.1 ppm
Arsenic<
0.05 ppm
Sulphate
< 250 ppm
Carbonate
Alkalinity < 120 ppm
Dissolved
Oxygen = 5 to 6 ppm
B.O.D—NIL
Any
parameter above the limits as mentioned above will require treatment .
TABLE OF WATER PROBLEMS AND SOLUTIONS
:
Problem
|
Process
|
How it Works
|
Equipment Used
|
Turbidity
- cloudy water that will clear if left to set for a few minutes
|
Filtration
|
Mechanically
traps particles between pores of media
|
Filter
tank and media with automatic
backwashing head. Media will vary depending on application
|
Turbidity
- cloudy water that will not clear
if left to set for a few minutes.
|
Flocculation
|
Chemicals
are added that will grow large particles that will settle out and then can be
mechanically removed by filtration
|
|
Low
pH - Blue-green staining-pin hole leaks in pipes caused by corrosive water
|
Acid Neutralisation
|
There
are two ways to do this:
1.
Dissolves sacrificial media (limestone) to raise pH and at the same time
increases the hardness.
2.
A pump injects a solution that raises the pH. The solution is usually made by
dissolving soda ash (baking soda) or potash (baking soda with potassium
instead of sodium)
|
Filter with AN (acid neutralizer)
for technique #1 and solution
feed pump for technique #2.
|
Gas
and VOC removal. Not for hydrogen sulfide removal. Radon at less than
5000pCi/L
|
Adsorption
|
Gases
attach themselves to the surface of the activated carbon. The carbon must
eventually be replaced
|
Filter with GAC (granular
activated carbon)
|
Iron,
manganese and hydrogen sulfide- Staining and Odor problems. hydrogen sulfide
has an odor that is usually egg like. The staining can be any color from
orange to brown to black
|
Oxidation
Filtration
|
The
material being removed is first oxidized . The
oxidation causes a precipitate
to be formed. The precipitated material is filtered. For instance, to remove
iron the oxidation causes the dissolved iron to turn to rust and make the
water cloudy red. Once the iron has rusted, it is a particle that can be
mechanically filtered.
|
Air injection systems
use air for the oxidation process and chlorine systems use chlorine for the
oxidation process. Air is introduced by a venturi and chlorine maybe introduce
by either a solution feed pump or a dry pellet down the well chlorinator. The
filter maybe any of the mechanical filters mentioned above.
|
Hardness,
iron, manganese, tannins - Hardness causes scaling. Iron and manganese stains
will have colors ranging from orange to black. Tannins will make the water
tea colored.
|
Ion Exchange
|
The
system simply replaces the material that is to be removed with one that is
more desirable. The total amount of material in the water does not change,
only the kind of material. The materials that are usually introduced into the
water are either sodium or potassium. Chloride ions will be added only when
an anion resin is used.
|
Water
Conditioner (softener) with either cation or anion resin. The anion will only
be used when there is a tannin problem. See our Technetic water softener
|
TDS,
salt, nitrates, gross alpha
|
Reverse Osmosis (RO)
|
RO
uses pressure to force water through a plastic membrane leaving the minerals
behind where they are flushed down the drain. Although this is not
filtration, many people visualize this as filtration on the atomic level
because molecules are being separated from one another. RO is usually done at
the point of use (POU) and only for the water that will be used to drink or
cook with.
|
Reverse osmosis system at
either the point of use (POU) or point of entry (POE).
|
Radon
|
AERATION
|
Aeration
drives the radon gas off by bubbling air through the water. The agitation
caused by the air removes the gas in a similar fashion to shaking a soda to
make it fizz.
|
Shallow tray aeration from NEEP
.
|
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