Reverse OsmosisGroup 1
Abhishek PatilPiyush Hatwalne
Naman Shukla
Various Filtration Processes
Fundamental Equation Regarding Reverse Osmosis
• The basic and far most important equation is π = CRT
Where π : Osmotic pressure.
C : Concentration of the solute. R : Gas constant. T : Temperature.
Flow Governing Equations
Water Transport:Qw = ( ∆P - ∆Posm) * Kw * S/d
Salt Transport:Qs = ∆C * Ks * S/d
Salinity: Cp = Qs/Qw
Industrial Application - Desalination
Desalination Techniques Overview
• Electrodialysis.
• Multiple-effect distillation.
• Multi-stage flash distillation.
Performance limiting factors of reverse osmosis plant
• Concentration Polarization
– Caused due to particulate matter accumulating near the membrane
• Membrane Deterioration
– Fouling• caused by deposition of organic matter on membrane
– scaling • caused due to deposition of inorganic salts on membrane pores
Module DesignThere are two major types• Hollow fiber module
– The water flows from outside the fiber while permeate is processed inside the lumen.
• Spiral wound module(SWM)– The SWM consist of several flat sheet membranes that are glued together to form a
membrane pocket.
Internal staging design
Desalination plants based on RO membrane technology are usually multiple stage processes. There are three basic plant designs for straight-through operation and a selection of a proper design will depend on plant capacity and production requirements
Pretreatment of feed water
• Chlorination
• pH Adjustment
• Anti-Scaling
• Dechlorination
Post TreatmentUntreated permeate from reverse osmosis plants does not conform with drinking water standards. It is often corrosive due to lack of TDS. Rehardening of water is done to make water potable.
Advantages and Disadvantages of R.O.
Advantages Disadvantages
Energy Requirement is low compared to other thermal Processes
Pre-treatment is always required before reverse osmosis
RO systems can be installed on very small household basis, where other systems are not portable
Low Chemical Compatibility-highly sensitive to pH cannot be used with even traces of oxidants like Cl2
Very High Salt rejection rate (>99%) Not compatible with micro organisms which have acetate attacking enzymes
Excellent rejection of Microorganisms and organic compounds
Suitable membrane should posses following properties:-
● High permeability to water.
● High impermeability to solutes.
● Ability to withstand high pressure without failure.
● Resistant to physical, chemical, and biological attacks.
● Tolerant of pH and temperature changes.
● Economical, to decrease the operating cost.
Examples:-• Cellulose membrane.• Polyamide.
Suitable Membrane Materials
Scope For Future Research
• Membranes
• Energy Recovery
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