Double Revolving field theory-how the rotor develops torque
Membrane process for water treatment
1. Microfiltration
• Microfiltration is an inexpensive membrane separation process for water
treatment.
• The membranes of microfiltration process are made of polypropylene, nylon,
acetonitrile, etc.
• Microfiltration used to
Reduce turbidity of water
Reduce suspended substance from water
Reduce bacteria from water
2. Advantages
• Can reduce amount of treatment
chemicals.
• Can reduce amount of micro-organism
present in water
• Reduce labour requirement.
• Treatment cost is lower than
conventional treatment.
Microfiltration
Disadvantages
• May need pre-treatment to prevent
fouling, scale formation.
• May required replacement of
membrane in each 3-5 year
• Scale formation may causes serious
problem.
• Flux rate may decline with time
• May require residual handling and
disposal of concentrate.
3. Application area
• Aerobic biological treatment
• Anaerobic biological treatment
• Membrane aeration biological treatment
• Pre-treatment for effective disinfection
• Pre-treatment for reverse osmosis and nanofiltration
Microfiltration
4. • Is a similar process to microfiltration
• The ultrafiltration membrane has small pore size which reject dissolve compound
with higher molecular weight such as colloids, protein and carbohydrates.
• But the membrane cannot remove salt or sugar.
• Used in industrial application for the production of high-purity process rinse
water.
Ultrafiltration
5. • Can reject particles as small as 1nm
• Used for removal of selected constituent from waste water.
• Both inorganic, organic compound, bacteria and viruses are removed
• Membrane used in nanofiltration are made of polyamide fibres, polyvinyl acetate,
cellulose acetate.
Nanofiltration
6. Reverse osmosis
• Reverse osmosis (RO) is a water purification
process that uses a partially permeable membrane
to separate ions, unwanted molecules and larger
particles from drinking water.
• RO is a process by which a solvent passes
through a porous membrane in the direction
opposite to that for natural osmosis when
subjected to a hydrostatic pressure greater than
the osmotic pressure.
7. Working mechanism
• In reverse osmosis process, two solution having different concentration (having
different chemical potential) are separated by semipermeable membrane.
• Fresh water will trends to diffuse through membrane from higher concentration side
to lower concentration side due to applied pressure which is higher than the osmotic
pressure.
Reverse osmosis cont.….
