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Flocculation is a process whereby small particles in suspension are caused to aggregate, giving large clusters (flocs) that are much more easily separated than the original particles. The process is in widespread use in many industrial applications.
What is meant by flocculation?
Flocculation is a process by which a chemical coagulant added to the water acts to facilitate bonding between particles, creating larger aggregates which are easier to separate. The method is widely used in water treatment plants and can also be applied to sample processing for monitoring applications.
Why is flocculation necessary for suspension?
The addition of the flocculating agent, at some critical concentration, negates the surface charge on the suspended particles and allows the formation of floccules or clusters as particles are held loosely together by weak van der Waals forces.
How is flocculation achieved in suspension?
Deflocculated suspensions of coarse powders tend to cake as the individual particles settle out and form compact, cohesive sediments. Controlled flocculation of bismuth subnitrate suspensions was achieved by the addition of small amounts of bentonite.
What is flocculation and Deflocculation?
The key difference between flocculation and deflocculation is that flocculation is the formation of flocs by the clumping of fine particles, whereas deflocculation is the dispersion of flocs to form a stable colloid. Flocculation refers to the formation of clumps from fine particles in a colloid.
What is an example of flocculation?
Flocculation and coagulation treatment chemicals are used in effluent wastewater water treatment processes for solids removal, water clarification, lime softening, sludge thickening, and solids dewatering. Examples of ChemTreat coagulation products include aluminum salts, iron salts, and polyelectrolytes.
Where is flocculation used?
Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water.
What chemicals are used in flocculation?
Chemicals (coagulants) are added to the water to bring the nonsettling particles together into larger, heavier masses of solids called floc. Aluminum sulfate (alum) is the most common coagulant used for water purification. Other chemicals, such as ferric sulfate or sodium aluminate, may also be used.
What is the difference between flocculant and coagulant?
Flocculants differ from coagulants in that they are often polymers, whereas coagulants are typically salts. Generally speaking, anionic flocculants are used to catch mineral particles while cationic flocculants can capture organic particles.
How can flocculation be prevented?
When particles of a suspension come close together they can form aggregates called flocculates which will settle more rapidly. To prevent that we often coat the particle with a charged surfactant. The charge (Zeta potential) acts to keep the particles separate and prevent flocculation.
What can be used as a flocculant?
The following natural products are used as flocculants: Chitosan. Isinglass. Moringa oleifera seeds (Horseradish Tree) Gelatin. Strychnos potatorum seeds (Nirmali nut tree) Guar gum. Alginates (brown seaweed extracts).
What are the suspending agents?
A suspending agent is a liquid in which a solid substance can be held in suspension. If the tablet is dissolved in a suspending agent, this will help suspend any insoluble components in the liquid. A suspending agent is a liquid in which a solid substance can be held in suspension.
How suspension are formed?
A suspension is defined as a heterogeneous mixture in which the solid particles are spread throughout the liquid without dissolving in it. If we take a glass full of water and mix mud in it, it will form a heterogeneous mixture.
What causes flocculation?
In dispersed clay slurries, flocculation occurs after mechanical agitation ceases and the dispersed clay platelets spontaneously form flocs because of attractions between negative face charges and positive edge charges.
What are the advantages of suspension?
The following advantages can be obtained by formulating API as a suspension dosage form. Suspensions are a useful drug delivery system for therapeutic agents that have a low solubility. Pharmaceutical suspensions may be formulated to mask the unpleasant/ bitter taste of drug.
What is flocculation value?
Flocculation value is defined as the minimum concentration required of an electrolyte to cause the coagulation or flocculation of a solution. Flocculation value is inversely proportional to the coagulating power of the ion.
Is alum a coagulant or flocculant?
To accomplish this, the water is treated with aluminum sulfate, commonly called alum, which serves as a flocculant. Raw water often holds tiny suspended particles that are very difficult for a filter to catch. Alum causes them to clump together so that they can settle out of the water or be easily trapped by a filter.
Which coagulant is used for sewage treatment?
Ferric chloride is widely used for sewage treatment and Alum is widely used for water treatment.
What happens flocculation?
Flocculation is a two-step particle aggregation process in which a large number of small particles form a small number large flocs. Small particles usually carry negative surface charges that hinder aggregation and settling (1a). Coagulant chemicals can adsorb to the particles and balance the charges.
Is Lime a coagulant?
Lime (Ca(OH)2 or CaO): Lime, or calcium hydroxide, is predominantly used to adjust pH, but as a softener, it can also be used as a coagulant aid. The lime bonds with the other particles and increases the size/weight of the flocs which then increases the speed with which they settle out of the water.
How often can you use flocculant?
You can reuse a clarifier after 5-7 days, but if you’re constantly seeing cloudy water, there may be other problems. Adding too much flocculant can cause its own issues.
Is flocculant and clarifier the same thing?
The main difference between the flocculant and pool clarifier is where the clumped particles go. You can also leave the pool filter off overnight while the pool floc goes to work, which is one less thing to do. Flocculant also works much faster than the pool clarifier.
Why alum is commonly used coagulant?
To induce coagulation, a coagulant (typically a metallic salt) with the opposite charge is added to the water to overcome the repulsive charge and “destabilize” the suspension. For example, the colloidal particles are negatively charged and alum is added as a coagulant to create positively charged ions.
