this presentation gives an overview of various membrane separation process

1. Membrane Processes and
Applications in Industrial Water
and Wastewater Treatment

2. General Definition
 Membrane Processes include a broad range
of seperation processes from filtration to
ultrafiltration and reverse osmosis.

3. Types of Membrane processes
 Microfiltration (MF)
 Ultrafiltration (UF)
 Nanofiltration (NF)
 Reverse Osmosis (RO)
 Dialysis / Electrodialysis (ED)

4. Examples for Applications of
Membrane Processes
 Desalting seawater
 Treating brackish groundwater
 Water softening
 Waste water recovery
 Removing color, odor, and other organic
contaminants

5. Process Configuration - General
Concentrate
Product
Feed
Influent to the
membrane module:
Feed water / feed stream
Liquid that passes through the
semi-permeable membrane:
permeate / product stream /
permeating stream
Semi-permeable membrane
Liquid containing the retained constituents:
Concentrate / retentate / reject / retained phase /
waste stream

6. A membrane is a film.
 A semi-permeable membrane is a
VERY THIN film that allows some
types of matter to pass through
while leaving others behind.

7. Membrane Types
ED MF UF NF RO
Retained
Water,
TSS,
microbes
uncharged
molecules
Larger
particles
Larger
molecules
Higher
charged
ions
almost
everything
Transported Dissolved
salts
Dissolved
salts,
small
particles
Small
molecules
and ions
Mono-
valent ions,
small
molecules
Very small
uncharged
molecules

8. Ultrafiltration
Primarily a concentration process
Pumping energy is required to force liquid through the
membrane
Relatively large size particles (MW 10000 – 40000<) are
retained and concentrated
Potential use in the recycling of metal containing alkaline
cleaner wastes and paints (concentrate)
Reduction of metals in industrial wastes

9. Ultrafiltration
 Does not change the chemistry of water.
For example to obtain potable water from surface
water, which is chemically clean, but contains algea
and bacteria, UF can be used.
Same water quality with coagulation / flocculaltion
 Removes turbidity
UF removes larger organics, colloids, bacteria while
allowing most ions and small organics to permeate
the porous structure.
Larger pore size  Requires much lower differential
operating pressure.

10. Ultrafiltration
 Cross flow or transverse flow
 Any membrane configuration
 Use re-circulation for high TSS
 Operating pressures ~ 50 psi
 Uses back flush to loosen fouling
 Excellent pretreatment for RO or Post
treatment for ED.

11. UF can replace several
conventional processes

12. Ultrafiltration
May be considered as pre-treatment before R/O to
prevent clogging of membranes.
Applications in industrial wastes:
Metal industry  Seperation of water-oil emulsions
Automotive painting industry  to seperate dye from
washing water
Pharmaceutical industry  Seperation of enzymes
Food industry  Cheese waste

13. Reverse Osmosis -
a Natural Process
 Reverse osmosis is a water purification process
that uses a semi-permeable membrane (synthetic
lining) to filter out unwanted molecules and large
particles such as contaminants and sediments like
chlorine, salt, and dirt from drinking water.
In addition to removing contaminants and
sediments, reverse osmosis can also remove
microorganisms – which you certainly do not want
to drink.

14. Osmosis
 osmosis is the process by which
water passes through a semi-
permeable membrane from a less
concentrated solution into a more
concentrated one.
 In other words, the pure water
passes through the filter to the
contaminated water in order to
equalize the concentrations.
 This movement generates osmotic
pressure.

15.  In reverse osmosis, an applied
pressure is used to overcome the
osmotic pressure and push the
water from high concentration of
contaminants to low
concentration of contaminants.
 This means it’s being forced in
reverse and the contaminated
water is trying to move into the
pure water, but because it must
pass through a filter first, the
contaminants get trapped and
only the pure water passes
through; resulting in the cleanest
possible drinking water – which
is exactly what we want

17.  Reverse osmosis typically involves four stages of filtration:
a sediment filter, pre-carbon block, reverse osmosis
membrane, and post-carbon filter.
 The sediment filter removes the largest particles, like dirt,
sand, and rust to prevent clogging of the subsequent filters.
 The pre-carbon filter uses activated carbon to prevent
anything larger than a spec of flour from passing through as
well as attracting and bonding with positively charged ions
to prevent chemical compounds, like chlorine and
chloramines, from passing through to the third filter.
 The reverse osmosis membrane then removes molecules
heavier than water, such as sodium, high levels of lead,
dissolved minerals, and fluoride.
 Finally, the post-carbon filter polishes the water

18. One Stage - Elements in Parallel

19. Two Staged System - 2:1 array

20. Reverse Osmosis
 Spiral wound or hollow fine fiber
 Pretreatment is critical to success
 Operating pressures from 150 - 1000 psi
 Removes >95-99% TDS
 Concentrate Stream is 15-25% of flow
with 4 to 6 times the TDS.

21. Freezing
 When waste water freezes, it can be purified
through the formation of a cleaner layer of ice.
 The clean layer of ice can be removed from the
rest of the waste water, and the remaining waste
water is more concentrated.
 The new energy-efficient method of purification
is based on the natural freezing process of water:
energy is required only for breaking the ice and
transporting it from the waste water pool.

22.  In practice, this method could be used by
leaving waste water from mines to freeze in
special pools under the open sky, after which the
cleaner part could be removed by breaking the
ice.
 After that the ice would be taken away using a
machine designed for that purpose to another
pool where the treated waste water would be
recycled, or undergo further treatment using
membrane filtration, for example, for the needs
of various processes.
 Recycling water from the industrial process
would reduce the amount of fresh water that is
used.

23. Elutriation
 Elutriation is a process for
separating particles based
on their size, shape and
density, using a stream of
gas or liquid flowing in a
direction usually opposite
to the direction of
sedimentation.
 This method is mainly used
for particles smaller than 1
μm.

24. Removal of Colour, Odour and Taste
 Potable water supplies and manufacturing or
processing of food and drinks demand water that is free
from tastes, colour and odour.
 Phenols combine with chorine and form cholorophenol
( medicinal taste).
 Dissolved gases and algae also cause taste and odour
problems.
 Chlorine, KMnO4 and ozone are strong oxidizing
agents and capable of removing odour and taste most
popular is breakpoint chlorination.

25.  Algae can be controlled by copper sulphate or other
herbicides.
 Chlorine, chlorine dioxide and ozone also remove
colour, odour and taste.
 In general, taste, odour and colour can be removed by
adsorption on activated carbon.
 10 to 50 mg/l of dosage in flocculation basins or
filters.
 As it is costly, its use is limited to food and beverages.
 Activated carbon is regenerated by heating to 1000 0 C.

26.  Screenshot 2022-08-02 at 9.25.25 AM

28. Ozonation

29. Removal of Iron and Manganese
 Iron and Manganese are like brothers and mostly live
together.
 Fe and Mn are soluble only in the absence of dissolved
oxygen and at low pH values of below 6.5.
 Iron is mostly available water as ferrous carbonate
FeH2(CO3)2.
 After oxidation or aeration it turns into an insoluble ferric
form that can be removed by settlement and filtration.
 Thus iron is removed by aeration of water and pH
adjustment to above 6.5.
 For removal of Manganese, pH should be higher than for
removal of Iron.
 Oxygen required for oxidation is supplemented by KMnO4,
Zeolite regenerated with KMnO4 or a normal sand fiiler
remove manganese