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Note: Also see
our Nominal Rejection Characteristics for
membrane rejections of common contaminants.
Are Lead and Arsenic Removed by Thin Film Reverse Osmosis Membranes?
What are the rejection rates?
There is not
a list of rejection rates for these heavy metals, but we can give you
some general guidelines. However, we recommend that you run the
experiments under your unique set of conditions and ions/counterions.
Rejection of lead by thin film RO membranes has been reported to be
quite high, >99%.
The rejection of arsenic depends on its oxidation state. The +3 acid,
arsenious, is not rejected particularly well in neutral solutions, 70 to
90%, but is well rejected as the pH approaches or exceeds the pKa of
9.2. The +5 arsenic acid is well rejected in neutral solution.
How efficient is reverse osmosis system in
screening out volatile chemical? such as MTBE, MTM, etc?
Reverse
Osmosis does not effectively remove these chemicals. In fact, such
chemicals can damage membrane elements.
In water showing 5400 ppb iron, 440 ppb zinc,
and 270 ppb aluminum, would a manganese-greensand filter have any effect
on the zinc and aluminum levels?
No. The levels of zinc and
aluminum will be unaffected by the manganese greensand filter. Reverse
osmosis will remove these metals, but a 2-pass RO system is
recommended .
Can I remove hydrochloric and phosphoric
acid from water using RO?
No. This is not a good
application for RO.
Can Water containing Hydrocarbons in ppb
levels (like benzene and other aromatic , aliphatic hydrocarbons) be
treated by Membrane Technology?
No. Hydrocarbons are not
removed by membranes.
What effect does hydrogen
sulfite and/or manganese have on RO membranes? If any, what levels
would the membranes tolerate?
Hydrogen
Sulfide would have no effect on the membranes, and is not removed by the
membranes.
Manganese will foul the
membranes and can cause fouling at levels in excess of 0.2 ppm in water.
Nano-filtration shows negative
rejection of Nitrates and very low rejection of Chlorides. Is this
correct?
Yes, This is
typical of nanofiltration membrane performance.
Is it possible to remove
formaldehyde from water by using RO? If so, which membrane would
you recommend?
Membranes cannot be used to
remove formaldehyde from water.
Can I remove TCE
(trichloroethylene) from water using RO Membranes?
No. You will need a
specially designed carbon system for this application.
Will Microfiltration remove
Fluoride?
No,
Micro filtration will NOT remove Fluoride. However, reverse osmosis
has been used to reduce Fluoride content by 90-98%.
Can I remove nitrates from our
well water when using an RO unit?
Nitrate
removal when using reverse osmosis membranes is about 80%. So if you
currently have 40 ppm of nitrate, then your levels after treatment
should be around 8 ppm.
Can I remove Boron with your
R.O.?
Boron is
removed at an average of 50-70% using a thin film reverse osmosis
membrane. Please refer to the attached chart for additional information
on membrane rejection.
We are facing a problem with
scaling due to hard water, what would you suggest to solve the problem?
You may
consider using a water softener.
Do RO membranes reject antimony, arsenic, lead, and thallium?
Some general guidelines are given below, but need to be verified by
pilot testing for each situation.
Rejection of lead by thin film RO membranes has been reported to be
quite high, >99%.
The rejection of arsenic depends on its oxidation state. The +3 acid,
arsenious, is not rejected particularly well in neutral solutions, 70 to
90%, but is well rejected as the pH approaches or exceeds 9.2. The +5
arsenic acid is well rejected in neutral solution.
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