whole process of reverse osmosis.

1. GOVERNMENT ENGINEERING
COLLEGE,VALSAD
SUBJECT: REVERSE OSMOSIS
GUIDE BY:
SANDIP BHATT
PREPARED BY:
DAKHARA NIRMAL
(160190113009)
ENVIRONMENTAL ENGINEERING DEPARTMENT

2. OVERVIEW:
• Osmosis
• Reverse Osmosis Definition
• RO Fundamentals
• Reverse Osmosis Membrane
• Parameters Affecting RO Systems
• Air Gap Faucets
• RO Maintenance
• Troubleshooting
• Quick connect fittings

3. OSMOSIS:
• Osmosis is a natural phenomenon that provides water to all animal and
vegetable cells to support life.
• Water moves from a high concentration of water (less sugar/salt dissolved
in it) to a low concentration of water (more salt/sugar dissolved in it)
across a semi-permeable membrane
• This means that water can cross a selectively permeable membrane from
a dilute solution (less dissolved in it) to a concentrated solution (more
dissolved in it)

4. NET MOVWMENT WATER MOLECULES
•A semi-permeable membrane is a membrane which will allow only
certain molecules or ions to pass through
• Osmosis is very important in biology as it provides the primary means
by which water is transported in and out of cells

5. OSMOSIS : WORKING PROCESS
• Feed water flows into RO unit with the force of line pressure
• Water is forced through membrane by cross flow filtration
• Cross flow filtration is most commonly used in RO as it allows
membrane to continually clean itself
• Membrane then either rejects or repels contaminants
• Two exit streams generated: waste & product stream
• Waste stream consists of: A concentrate (reject) stream which carries
contaminants (compounds too large to pass through membrane)
• Permeate stream consists of: Product water which has been forced
through the membrane & is virtually free of TDS

6. REVERSE OSMOSIS:
• RO is a form of filtration using osmosis in reverse
• Water passes from a more concentrated solution to a less
concentrated solution
• To accomplish this a force or pressure MUST be applied
• RO requires 1 psi of pressure for every 100 ppm of TDS
• RO is used to remove dissolved solids from water but it can
also improve taste, odor & color of water
• RO membranes have the capability to remove particles as
small as ions i.e. magnesium ions or sodium ions
• RO membrane will reject most compounds based largely on
size
• Dissolved ions, such as salts, carry an electric charge and will
also be rejected by membrane

7. SCHEMETIC
DIAGRAM:

8. RO FUNDAMENTALS:
FEED WATER: Main flow of impure water to be treated;
PRODUCT WATER:Portion of fee d water which passes through membrane
as permeate
REJECT WATER: Portion of feed water which did not pass through
membrane; carries impurities to drain
MODULE: Combination of spiral round membrane element &
pressure vessel

9. RO
MEMBRANE:
•Membrane is the work-horse of an reverse osmosis system
• When choosing an RO system you must do so wisely – taking into account
water quality is very important
• Two main types of membranes:
1. CTA membrane:• Cellulose acetate/triacetate
blend• Provides lowest cost per gallon of
water• Resists chlorine but has a lower flow rate limit in
applications of high water consumption
2. TFC membrane:• Thin film/thin layer
composite• Can handle high flow, has a high rejection rate & can
handle high water consumption
• Cannot handle chlorine concentrations; water must be
carbon pre- filtered

10. MEMBRANE
COMPARISON:CHARACTERISTI
CS
CTA MEMBRANE TFC MEMBRANE
1. Advantages Chlorine Tolerant pH Tolerant
Low Price High Rejection &
Flow
2.
Disadvantage
s
pH Intolerant Chlorine Intolerant
Medium Rejection High Price
3. Municipal Water Low Temperature &

11. PARAMETERS THAT AFFECT
RO:Water Temperature:RO system ratings are based on 770F/ 250C water
temperaturei.e. : RO system rated at 20 GPD (gallons per day) at
340F/10C will only produce 6 GPD
Feed Water
Pressure:
A lack in water pressure (less than 40 PSI) will reduce
product water; this can be helped with the aid of a
booster pump
Contaminants in
Feed Water:
Large particles, iron concentration or high levels of
hardness in feedwater can cause clogging of the
membrane can decrease its life
Microorganisms: RO membranes can filter out bacteria, depending on the
bacteria size, however this may cause fouling of the
membrane as bacteria can begin to grow through pores
of membrane causing BACTERIA CREEP – RO systems
should not be installed on non-potable

12. RO SYSTEMS CAN REMOVE THE FOLLOWING CONTAMINANTS
• Dissolved solids = TDS (salts & minerals) – UP TO 2000 ppm
• Most Heavy metals (lead, mercury,
silver)
• Most radioactive elements
• RO systems may not be capable of removing
nitrates to recommended levels

13. RO TREATED WATER:
• RO systems will remove up to 97% (depending on
parameters) of salts in water bringing it closer to a level of
‘pure water’• The purer the water, the more aggressive it will be with
materials it comes in contact with feed water
• THEREFORE RO can be slightly corrosive
• It’s recommended NEVER to use copper piping on RO water

14. TYPICAL CONSUMER RO SYSTEM:
PREFILTER
TANKTo
Drain
RO MEMBRANEPOSTFILTER
AIR GAP FAUCET

15. AIR-GAP FAUCETS:
• ‘Air gap’ faucet is a plumbing device designed to provide a siphon break
for an under-sink reverse osmosis unit
• It is a valve used to isolate one part of a water system
from the drain
• Air gaps are designed to prevent backflow by incorporating a “backflow
prevention” method called an ‘air gap’
• Some plumbing codes do enforce the use of an Air
Gap faucet
• Purpose of an air gap faucet is to assure that no water from a
stopped-up sink can possibly be forced backward into your reverse
osmosis system unit via its drain connection

16. RO SYSTEM
MAINTENANCE:When to Replace Pre-
filters:
• Every 6 months for normal installations.
• After a Boil Water Advisory (BWA)
When to Replace Post-filters:• Every 6 months, depending on water conditio
• Noticeable decrease in water production
indicates that the pre-filter should be
changed.• After microbiological contamination,
such as in a Boil Water Advisory
(BWA)

17. When to Replace the Membrane:
• Typically, every 18 months to 3 years
• Test using a TDS (total dissolved solids) meter. Replace a
membrane below 80% TDS reduction.
• This will depend on influent water quality, usage, pre & post
filter maintenance• Maintain filters, lengthen life of membrane!!!

18. TROUBLESHOOTIN
G:No Permeate Water: • Membrane
Fouling• Pre-filter Fouling
• Inadequate Pressure
Slow Flow at the
Faucet:
• Air Charge
• Tank not
filling• Installation of tank,
tubing length
• Inadequate
Pressure

19. QUICK CONNECT
FITTINGS:• RO systems cannot be installed using copper piping as product
water is slightly aggressive
• Plastic tubing is most commonly used in RO installations
• Pipe connections are accomplished using Quick Connect Fittings
• Quick Connect fittings do NOT need any
additional special tools
• Simply cut tube square & insert into
QC fitting to accomplish a secure
connection

20. THANK YOU