|
Q. WHAT IS
REVERSE OSMOSIS (RO)?
Q. WHAT
IS AN RO SYSTEM?
Q. FACTORS
AFFECTING AN RO SYSTEM
Q. DOES AN
RO SYSTEM DISINFECT WATER?
Q. HOW
DOES AN RO SYSTEM KNOW WHEN TO PRODUCE WATER?
Q. WHAT
DOES A TYPICAL RO TAKE OUT OF WATER?
GLOSSARY OF TERMS
REVERSE OSMOSIS INFORMATION
Return
to top
WHAT IS REVERSE OSMOSIS (RO)?
Reverse osmosis (RO) is a water
treatment process that removes undesirable materials from water by using
pressure to force the water molecules through a semi-permeable membrane.
This process is called "Reverse" Osmosis because a concentrated
water solution (raw) is forced under pressure through a membrane to yield
a diluted water solution (treated) for consumption. This treated water
does not contain contaminants such as; chemicals, ionized salts, heavy
metals, collides and organic molecules. The RO reduces the molecules down
to a molecular weight of 100 and the rejection of dissolved salts is typically
95% to greater than 99%. Reverse Osmosis is the finest level of filtration
available.
Return
to top
WHAT IS AN RO SYSTEM?
A typical system consists
of:
-
One or more Pre-filters to remove
silt, iron, chlorine or other particulate matter.
-
A membrane to remove raw water
contaminates.
-
A pressure sensitive hydraulic on/off pressure valve to send pre-filtered
water to the membrane to make treated water for storage.
-
A small storage tank for treated water.
-
May includea post-filter to
polish stored water and to maximize its taste just prior to consumption.
Return to top
FACTORS AFFECTING AN RO SYSTEM
Permeate flux
and salt rejection are the key performance parameters of the reverse osmosis
process. They are mainly influenced by variable parameters such as; pressure,
temperature, recovery, and feed water salt concentration.
Pressure
Increased
feed water pressure will increase permeate flux and decrease the permeate
TDS. With excessive pressure the membrane may become deformed or compacted
and a decrease in product flow will result.
Temperature
Increased
temperature will increase permeate flux, which increases salt passage.
It is also important to note that every unit is rated for a product flow
temperature of 77°F (25°C). With a temperature decrease, the product flow
will decrease. On average the membranes lose about 2% production for every
degree below 77°F.
Recovery
The
recovery is the ratio of the permeate flow to the feed flow. When recovery
is increased, the permeate flux will decrease and the salt passage will
increase.
Feed
water Concentration
Increased
TDS or salt concentrations will decrease permeate flux and increase salt
passage. This can also lead to surface coating or fouling by the salt.
Return
to top
DOES
A RO SYSTEM DISINFECT WATER?
While
the membrane used in an RO system will physically screen out and remove
many microorganisms in water, including pathogenic bacteria, the system
must not be relied upon to make a biologically questionable water supply
safe and potable for consumption. Membrane imperfections or faulty water
seals in the system could allow untreated water to pass through and over
time bacteria could grow on or through the membrane. Be sure the
raw water source for your RO system is safe and potable for consumption
by having a sample tested by a certified water testing facility. If you
want guaranteed disinfected water Nature’s Beverage sells a RO System
that has a UV generator unit that system water passes through before going
to an RO faucet.
Return
to top
HOW
DOES AN RO SYSTEM KNOW WHEN TO PRODUCE WATER?
A
standard RO System has a hydraulic on/off pressure valve which is
controlled by source water pressure to send pre-filtered water to the
membrane to make water for storage.
When
water pressure in the storage tank builds up to 90% of the incoming line
pressure, the standard hydraulic on/off pressure valve shuts off the flow
of water to the system, stopping treated water production. When you open
the RO faucet, system pressure drops as treated water exits the tank.
The standard hydraulic on/off pressure valve turns on when the tank pressure
is less than the source water pressure and treated water is produced through
the RO system. The cycle repeats itself.
Return
to top
|
WHAT
DOES A TYPICAL RO TAKE OUT OF WATER?
| CHEMICALS |
REDUCES
BY
|
|
OTHER
COMTAMINENTS
|
REDUCES
BY |
| THMs (chloroform) |
95% |
|
barium |
97% |
| benzene |
83% |
|
bicarbonate |
94% |
| carbon tetrachloride |
87% |
|
cadmium |
97% |
| p-dichlorobenzene |
93% |
|
calcium |
97% |
| TCE (trichloroethylene) |
98% |
|
chromate |
92% |
| 1, 1-dichloroethylene |
86% |
|
copper |
97% |
| 1, 1, 1-trichloroethane |
93% |
|
detergents |
97% |
| 1, 2-dichloropropene |
95% |
|
fluoride |
90% |
| cis-1,3-dichloropropene |
95% |
|
lead |
97% |
| chlorobenzene |
95% |
|
magnesium |
97% |
| ethylbenzene |
95% |
|
nickel |
97% |
| hexachlorobutadiene |
95% |
|
nitrates |
80% |
| ortho-xylene |
95% |
|
total dissolved solids |
95% |
| PCE (tetrachloroethylene |
95% |
|
potassium |
92% |
| toluene |
95% |
|
radium |
97% |
| trans-1, 2-dichloroethene |
95% |
|
selenium |
97% |
| 1, 1, 2, 2-tetrachloroethane |
95% |
|
silicate |
96% |
| 1, 2-dichlorobenzene |
95% |
|
silver |
85% |
| 1, 2-dichloropropane |
95% |
|
sodium |
92% |
| 1, 1-dichloroethane |
95% |
|
strontium |
97% |
| chlorine |
99% |
|
sulfate |
97% |
| EDB |
99% |
|
PCB's |
97% |
| DBCP |
99% |
|
insecticides |
97% |
| Atrazine |
97% |
|
herbicides |
97% |
|
Return
to top
GLOSSARY
OF TERMS
| Absorbate: |
Material
to be removed from solution.
|
| Absorbent: |
Material
on which absorption will occur.
|
| Air Gap: |
A
clear vertical space between the end of the RO drainline and the
flood level rim of the house sanitary drain system connection point.
|
| Concentrate/Reject: |
The
portion of water that does not pass through the membrane and goes
to the drain.
|
| Feed Water: |
An
incoming water source to the RO system.
|
| Flux: |
The
rate of transfer of fluid, particles, or energy across a given surface.
|
| GAC: |
Granular Activated Carbon is regarded
as one of the most effective water treatment materials in absorbing
many types of soluble organic materials found in water. |
|
| Membrane: |
A
thin layer that forms a barrier, selective to the passage of chemicals.
|
| Permeate: |
Portion
of the raw source water, which passes through the membrane. RO system
treated water for consumption.
|
| Reverse Osmosis: |
The
movement of raw source water through a semi-permeable membrane when
pressure is applied to yield treated water.
|
| Surface Area: |
The
surface of a material available for absorption to take place.
|
|
Thin
FilmComposite
(TFC):
|
Thin
membrane bonded to an anisotropic support layer. Synthetic fabric
supports this composite. Thin film offers highest degree of selectivity,
flux, and chemical stability.
|
| Total Dissolved Solids (TDS): |
Total
amount of dissolved solids/salts in raw/treated
(TDS)
water.
|
| Ultraviolet (UV) Light: |
Radiation
(Light) having a wavelength between 100-3900 angstroms.
|
| UV Germicidal Light: |
UV light that peaks at 2,537 angstrom wavelength and
is in a wavelength that lies between 200-300 nanometers which kills
all disease causing micro organisms. |
Return
to top
|
