How R.O. System works and comparison between different methods of water filteration.

1. Presented By:
Shah Utsav & Soni Nikita
Department of Textile Processing Technology
Dr. S. & S. S. Ghandhy College of Engg. & Tech.,
Majura Gate, Surat.
REVERSE OSMOSIS
“An ideal system of water softening”
1

2.  In early days simple forms of membranes are
used.
 Like sieves & cheesecloth membranes.
 Earlier separation & membranes are based on
particle size.
 But, now membrane technology have focused on
differences in solution and diffusion rates also.
2

3. General representation of a membrane separation process
3

4. Different Membrane-based processes
 Micro-filtration
operates on a particle size range of 0.10 µm to
0.15 µm.
 Ultra-filtration
operates on a particle size range of 0.15 µm to
5xl0-2 µm
 Nano-filtration
operates on a particle size range of 5xl0-2 µm to
5x10-3 µm
 Reverse osmosis
operates on a particle size range of 5xl0-3 µm to
10-4 µm.
4

5. 5

6. 6
Other Filtration processes Reverse Osmosis
separation is made by a
sieving mechanism
separation is made by a
osmosis mechanism
membrane passes smaller
particles and retains larger
ones
membrane passes only
solvent and retains the
solute
used to separate the
suspended particles
used to separate the
dissolved solid particles as
well as suspended solids
6

7. Why Reverse Osmosis….?
➢Water being a universal solvent & contains one or more
group of impurities.
➢The term water purification refers to leaving all kinds of
impurities behind.
➢There are number of methods for water purification.
➢These methods removed one impurity or a selected group
of impurities from treated water.
➢Only three scientifically recognized methods of water
purification:
(1)Reverse osmosis[RO]
(2)Freeze-thawing
(3)Distillation
7

8. ➢By the RO process:
(1) 93 to 99% reduction
of Pb+2,(PO4)-3,Ag+,
Zn+2, SO4
-2,Cr+6,
Fe+2,Mg+2 ions.
(2) 90 to 98% reduction
of SO2
-,Na+ ions.
(3) 85 to 95% reduction
of NO3
- ions.
(4) 70 to 80% reduction
of arsenic.
(5) Also remove
microbiological
contaminants like
viruses and bacteria.
8

9. Osmosis:
➢Osmosis is the natural tendency to balance the
chemical potential of liquid on both sides of the
membrane.
➢Flow always moves from lower to highly
concentrated side.
➢The concentration difference of liquid is
responsible for movement of flow.
➢The semi-permeable membrane does not
allow different particles from it but allows only
pure solvent to move.
9

10. Reverse Osmosis:
➢It is a process in which high pressure greater than
natural osmotic pressure is applied on the high
concentration side of the membrane.
➢Additional high pressure forcing the water to travel
through the membrane from higher to lower
concentrated chamber.
➢Thus, reverse osmosis is ‘reversing’ the natural
tendency of water flow.
➢That is why it is called Reverse Osmosis.
➢suspended as well as dissolved impurities are not
passes through ultra-fine pore size membrane.
10

11. 11

12. 12

13. Membrane
• A membrane is a selective barrier for
separation process.
• Purification of fluid is done by
combination of membrane and diffusion
mechanisms.
• Membranes can separate particles and
molecules as per particle size and
molecular weights.
13

15. Features of the RO Membrane
 It is of thin film of polymeric material having several
wound.
 High water permeability and a highly impermeable to
impurities.
 Must be stable over a wide range of pH and
temperature.
 Resistant to attack by chemicals like free chlorine and
by bacteria.
 Feed water quality, pretreatment conditions and
stability of operation are affect the Efficiency.
 The pore size for R.O membrane is around 0.0001
microns.
15

16. 16

17. Types of Reverse Osmosis Membranes:
(1) Cellulosic
(2) Fully aromatic polyamide
(3) Thin film composite
17

18. INDUSTRIAL WATER
PURIFICATION
RURAL WELL WATER
PURIFICATION
MUNICIPAL WATER
PURIFICATION
MEDICAL DEVICE
MANUFACTURING
SEA WATER
DESALINATION
WASTE WATER
RECYCLING
BRACKISH WELL WATER
DESALINATION
CAR-WASHES
"SPOT-FREE RINSE"
FOOD PRODUCTS
And
COSMETIC PRODUCTS
REVERSE OSMOSIS APPLICATIONS
LABORATORY
WATER PURIFICATION
BOTTLED DRINKING
WATER PRODUCTION
PHARMACEUTICAL
WATER PURIFICATION
Reverse
Osmosis
Applications
18 18

19. Important Parameters
• The following parameters are consider:
1. Osmotic and operating pressure
2. Concentrate disposal
3. Filtrate recovery
 If the operating pressure is low then net filtrate flow
rate across the membrane would be minimal or equal
to zero.
 Thus operating pressure is set at higher value in order
to maintain economical filtrate flow rate.
19

20. Single Pass RO & Double Pass RO System
(1 stage & 2 stage)
 In 1 stage RO system, feed enters RO system as one
stream and leaves as concentrate and permeate.
 In 2 stage, concentrate from 1st becomes the feed
water to the 2nd stage. Permeate water from 1st stage
is collected and mixed with permeate water from 2nd
stage.
20

21. Double Pass RO
Single Pass RO
21

22.  Pre-Filter
 Carbon Filter
 Sediment Filter
 Reverse Osmosis
Membrane
 Post Filter
 Automatic Shut Off Valve
(SOV)
 Check Valve
 Storage Tank
 Drain line
 Pump & Motor
Drinking Water R.O. System
22

23. Industrial R.O. System
23

24. Limitations
✓ It required carbon pre-filters because chlorine and
Volatile Organic Chemicals (VOC’s) are smaller than
water molecules & can’t be filtered by RO membrane.
✓ RO systems can produced only 15 gallon/day purified
water. So, this process is fairly slow.
✓ The maintenance of RO system must be done regularly.
✓ The RO membrane should be replaced every 2-3 years.
✓ Due to high pressure requirement RO is usually not
applicable for concentrated solutions.
✓ The RO process usually cannot be applied without
pretreatment.
24

25. For your kind attention…..!
25