8. Introduction
Membrane
The membrane, typically a synthetic material less
than 1 mm thick, is semipermeable—meaning
that it is highly permeable to some components
in the feed stream and less permeable (or
impermeable) to others. During operation,
permeable components pass through the
membrane and impermeable components are
retained on the feed side. As a result, the
product stream is relatively free of impermeable
constituents and the waste stream is
concentrated in impermeable constituents.
9. Introduction
• Membrane processes are modern physicochemical separation
techniques that use differences in permeability (of water
constituents) as a separation mechanism. During membrane
treatment, water is pumped against the surface of a
membrane, resulting in the production of product and waste
streams.
10. Introduction
Terminology in Membrane Separation Processes
• Feed: Volume or mass of solution enters membrane modules
(m3/sec)
• Flux: Number of moles, volume, or mass of a solution passing per
unit of time through a unit of membrane surface area (m3/m2.sec,
LMH)
13. Introduction Phase 1 is usually considered as
the feed or upstream side phase
while phase 2 is considered the
permeate or downstream side.
Separation is achieved because the
membrane can transport one
component from the feed mixture
more readily than any other
component or component.
However, it should be realized that,
in general, a membrane is not a
perfect (or ideal) semipermeable
barrier.
16. Introduction:
Advantages
Relatively Low-cost process
Producing effluents with very high quality
Flexible; can be used in the separation, concentration, and purification of
a huge variety of materials across a wide range of industries.
No phase change is involved; feed and product streams remain in liquid
form.
The processes can function effectively at low temperatures.
Processes are relatively simple to scale up.
Membranes can be manufactured in a uniform and highly precise manner.
17. Introduction: Limitation
Membrane fouling:
accumulation of pollutants inside
pores and on membrane surface
causing flux decline and
requiring modules replacement,
increasing energy, additional
cost, chemicals,…etc
Modeling & design:
Good theoretical frameworks,
are not feasible to predict the
performance from its structure,
nor the flux & flux decline from
knowledge of feed.
◦ Overcome by interpretation &
extrapolation of pilot plant data
Energy requirement
Based on the type of driving
force, increase the total cost
Materials
Not available
