Water Soluble Polymers For Industrial Water Treatment Applications/البوليمرات وانواعها واستخداماتها

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[left][u][b]Water Soluble Polymers For Industrial Water Treatment Applications

Presented By
General.dr
Bahaa badr

ORGANIC COAGULANTS

Organic polymeric flocculants have been used in water purification processes for several decades as
coagulant aids or floc builders, after the addition of inorganic coagulants like alum and iron salts.

The application of polymers as primary coagulants in cleaning up low quality natural waters for drinking
water production by direct filtration and weighted flocculation is discussed.

Presently, the whole or partial replacement of inorganic coagulant by cationic polyelectrolyte can
improve drinking water treatment processes.

The areas of application for organic coagulants include the following:
- clarification by settling
- flotation - clarification
- clarification by direct filtration

Organic Coagulation Advantages

Treatment Process Optimization

l An increase in the solid-liquid separation rate

l Low consumption of reagent compared with inorganic salts

l A smaller sludge volume is produced (no metal hydroxide precipitate is formed
)
l Extended filter runs are obtained in direct filtration

l The process is less pH dependent

l There is a reduction in usage of other treatment chemicals

l The treated water has a lower dissolved salt level

l Elimination of monocellular algae

Two main types of cationic polyelectrolyte are commonly used in water treatment
:

- polyAMINE

- polyDADMAC

The coagulants should provide a very high cationic charge to neutralize the negative charges of the
colloids and therefore initiate the floc formation.

Their molecular weight should be very low to insure a good diffusion of the charges around the
particleS.

Due to their low viscosity they can be readily mixed in the effluent.

POLYAMINES

Quaternary polyamines -poly ( 2 hydroxy propyl N,N dimethyl ammonium chloride)- are manufactured
by a ring-opening condensation polymerization of epichlorohydrin and a secondary amine, such
as dimethylamine, at high temperatures in concentrated aqueous solution.

Molecular weights can be varied from 10,000 up to 500,000 by controling the sequence of addition
of the monomers to the reaction vessel.

The structure of the resultant polymer differs from the other
polyelectrolytes, so that the cationic charges are situated along the backbone chain, and not as
pendant side groups.

Industrial polymers produced this way present the following characteristics:

l Molecular weight from 10,000 to 500,000

l Liquid form, active content from 40 to 50 %

l Cationic site on the main chain

l Viscosity, at 50 %, from 40 to 20,000 centipoises

l Chlorine stability

l Compatibility with mineral coagulants

l Long shelf life

POLYDADMAC

DADMAC (Diallyl dimethyl Ammonium Chloride) is synthesized from allyl chloride and dimethylamine.

In common with other monomers containing allyl groups, DADMAC forms a relatively
stable allyl radical during vinyl polymerization.

It limits, the molecular weight of the polymer.

l Usable with or without preliminary dilution

Industrial polymers produced this way present the following characteristics:

l Molecular weight from 10,000 to 3,000,000

l Liquid form, active content from 20 to 50 %

l Cationic site on the secondary chain

l Viscosity, at 40 %, from 1,000 to 22,000 centipoises

l Chlorine stability

l Compatibility with mineral coagulants

l Long shelf life

l Usable with or without preliminary dilution

Water Soluble Polymers For Industrial Water Treatment Applications

Presented By
General.dr
Bahaa badr

ORGANIC FLOCCULANTS

(Potable Water Grade) flocculants are used in conjunction with coagulants to increase
the settling speed.

After the destabilization of the colloidal suspension by coagulant, the flocculant
with its high molecular weight encourages fast settlement, according to Stokes’ law.

For drinking water, anionic ( 0 to 50 %) and low cationic (< 15 %) products with high molecular weight
have been used with success.

Stable colloidal suspension
Primary coagulant
organic and/or mineral
Coagulation stage
unstable colloid
microfloc formation
Secondary coagulant/flocculant
organic polymer
Flocculation stage
large flocs
Settling of suspension

During the coagulation/flocculation process, the organic or mineral coagulant quantity is limited to the necessary
quantity for destabilization of colloids and does not require excessive amounts to produce a suspension which will
settle.

Anionic and Non-ionic Polymers

Non-ionic polymers are Acrylamide homopolymers.

Anionic polymers are differentiated by a functional group. Two monomers are used: Acrylamide and Acrylic acid.

Non-ionic
These polymers are manufactured by polymerization
of acrylamide monomer
12
FLOPAMTM PWG Series
Stable colloidal suspension
Primary coagulant
organic and/or mineral
Coagulation stage
unstable colloid
microfloc formation
Secondary coagulant/flocculant
organic polymer
Flocculation stage
large flocs
Settling of suspension
During the coagulation/flocculation process, the organic or mineral coagulant quantity is limited to the necessary
quantity for destabilization of colloids and does not require excessive amounts to produce a suspension which will
settle.

Acrylamide Non-ionic polymer

- Molecular weight from 5 to 15 million

Anionic

These polymers are manufactured by copolymerisation of acrylamide and sodium acrylate

Polymer characteristics :

- Molecular weight from 5 to 22 million

- Easily absorbed by mineral matter

Cationic Polymers

Cationic polymers are manufactured by copolymerization of acrylamide and trimethyl ammonium ethyl acrylate
chloride (methyl chloride ADAM).
.

Polymer characteristics:

- Molecular weight from 3 to 15 million

- Easily absorbed by organic matter (humic and fulvic acids) and some mineral matter (silica)

» البوليمرات المستخدمة فى معالجة الصرف الصناعى السائل/ Ill. WATER SOLUBLE WASTE TREATMENT POLYMERS
» Industrial Wastewater Treatment/طرق المعالجة الكيميائية للصرف الصناعى وكل مشاكله
» البوليمرات المستخدمة كمجلطات وفلوكات ومروقات لمعالجة الصرف الصناعى/Polymers for Coagulation, Flocculation and Dewatering of Solids and Sludge
» water impurities in boiler water treatment/الشوائب فى مياه الغلايات
» AN INTRODUCTION TO CHEMICAL CLEANING OF INDUSTRIAL WATER SYSTEMS/طرق التنظيف الكيميائى لاجهزة معالجة المياه