How does Reverse
Osmosis work?
is
the
brand name given to a ultrapure reclaimed water.
It is produced after treated waste water (sewage)
is further purified using a 3-step process using
advanced
membrane
technologies
like
microfiltration and reverse osmosis, and a final
disinfection of the product water using ultraviolet
light.
To understand how "reverse osmosis" purifies
water, it is probably best to start with normal
osmosis.
Osmosis is a physical force. It is the "movement
of a solvent through a semipermeable membrane
into a solution of higher solute concentration that
tends to equalize the concentrations of solute on the
two sides of the membrane."
This 3-step purification process has enabled the
Public Utilities Board (PUB) to produce
consistently good quality NEWater.




NEWater is cleaner than potable PUB
water in its colour
NEWater is cleaner than potable PUB
water in its clarity
NEWater is cleaner than potable PUB
water in its level of organic substances
NEWater is cleaner than potable PUB
water in its bacteria count
NEWater is cleaner than potable PUB water
Now, for reverse osmosis:
Reverse osmosis (RO), water is forced
through a semipermeable membrane in the
opposite direction of the natural osmotic flow. The
process requires that a pressure in excess of the
osmotic pressure is applied to the solution that has
more solute concentration.
In
In most cases, the membrane is designed to allow
only water to pass through this dense layer while
preventing the passage of solutes (such as salt
ions) and is thus termed a semipermeable
membrane. The rejected impurities from the
concentrated side are washed away in the reject
water.
Next, let’s us look in detail
how pre-treated waste water
is purified through the
process of reverse osmosis to
get
NEWater
NEWATer …
turn overleaf to read more…
NEWater is the product from a multiple barrier
water reclamation process.



The first stage of the NEWater production
process: The first barrier is where the used
water is treated to globally recognised
standards in the Water Reclamation Plants
using the conventional wastewater treatment
process. The second barrier is the process
called Microfiltration where the treated used
water is passed through membranes to filter
out
suspended
solids,
disease-causing
bacteria, some viruses and protozoan cysts.
The 1st stage begins here where the filtered
water that goes through the membrane
contains only dissolved salts and organic
molecules.
The second stage: The third barrier is the
process called Reverse Osmosis (RO) where a
semipermeable membrane is used. The semipermeable membrane has very small pores
which only allow very small molecules like
water molecules to pass through but not
contaminants such as bacteria, viruses, heavy
metals, disinfection by-products, etc. This is
the 2nd stage. Hence, this RO water is free
from viruses and bacteria and contains very
low levels of salts and organic matters. At
this stage, the water is already of a high grade
water quality.
The third stage: The fourth barrier is where
ultraviolet or UV disinfection is used to
ensure that all organisms are inactivated, a
further safety backup to the RO in order to
ensure that the product water is pure.
With the addition of some alkaline chemicals to
restore the acid-alkali or pH balance, the
NEWater is now ready to be piped off to its wide
range of applications.
Factors affecting the Process Performance,


The water treatment systems must be well
maintained to ensure good performance. Eg.
screening of solids within the water to prevent
fouling of the membranes, thus reducing the
risk of damage to the high-pressure pump
components.
The performance of the system depends on
factors such as membrane type, flow control,
feed water quality, temperature and pressure.
Also only part of the water entering the unit is
useable, this is called the percentage recovery.
This is affected by the factors listed above.
For example the amount of treated water
produced can decrease by about 1-2% for
every 1 degree Celsius below the optimum
temperature.
Interesting Question :
Reverse
Osmosis
Untreated water
Is NEWater safe for human consumption? If so,
why can't we introduce NEWater straight into the
taps of our homes?
Ultra-clean & safe to drink
NEWater
Do you know that …
Singapore's Four National Taps refer to
the
4
sources
of
water
supply.
Yes, NEWater is safe for human
consumption. Unfortunately,
NEWater through the process of
purification, has been stripped
of those natural trace minerals
that our body needs.
Thankful to the following info:
<http://science.howstuffworks.com/reverse-osmosis.htm
www.accepta.com/industry_water...
en.wikipedia.org/wiki/Reverse_osmosis
www.pub.gov.sg/newater
The 1st 'tap' refers to the supply from our
local water catchments and reservoirs.
The 2nd 'tap' refers to the import of water
from the state of Johor in Malaysia under
two Water Agreement expiring in year
2011 & 2061. Our 4th 'tap' is seawater
desalination through which freshwater is
obtained .
Last, but not least, our third 'tap' ,
NEWater, recycles
osmosis technology
supply.
water via reverse
to reclaim water.er