Mechanism of clarification of colloidal suspension using composite dry powdered flocculant
Flocculation is a widely used process for particle removal in water/wastewater treatment. Clarification method by using composite flocculants in powder form has been proposed in the literature. Such composite flocculants are conveniently used in the flocculation process of small volume suspensions...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier Inc.
2016
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/50153/ http://irep.iium.edu.my/50153/ http://irep.iium.edu.my/50153/ http://irep.iium.edu.my/50153/1/Published.pdf |
| Summary: | Flocculation is a widely used process for particle removal in water/wastewater treatment. Clarification
method by using composite flocculants in powder form has been proposed in the literature. Such composite
flocculants are conveniently used in the flocculation process of small volume suspensions. In this
study, fundamental aspects of the clarification mechanism of the composite dry powdered flocculant
are investigated. 1.00 mg/mL suspension of polymethyl methacrylate particle (PMMA, 0.15 m in diameter)
is used as a colloidal material. A model composite flocculant comprising an inorganic flocculant
(aluminum sulfate), anionic polymer flocculant (copolymer of acrylic acid and acrylic amide), and a flocculation
aid (calcium carbonate) is studied. The effects of each component on turbidity removal are
examined. It is clarified that the order of addition, the state of polymer flocculant (powdered form or
liquid form), and combination of components (polymer flocculant with/without aid particles) are critical
for turbidity removal with combined use of flocculation aid, inorganic flocculant and polymer flocculant.
When the composite dry powdered flocculant is added to a colloidal suspension, the inorganic flocculant
dissolves immediately. The polymer flocculant particles disperse well in the suspension with the help of
flocculation aid particles and dissolve moderately. The ions from inorganic flocculant result in formation
of microflocs composed of both PMMA and flocculation aid particles. Flocculation aid particles play an
important role;i.e.they accelerate flocculation of PMMA particles and attenuate the ability ofthe polymer
flocculant particles to produce undissolved lumps.
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