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Flocculation is the separation of a solution, commonly the removal of sediment from a fluid. The term is derived from floc, which means flakes of material; and when a solution has been flocculated, the sediment has formed into larger aggregated flakes, making them easier to see and remove.
What is flocculation process?
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.
What is flocculation example?
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.
What happens in flocculation tank?
The flocculation tank has wooden paddle-type mixers that slowly rotate on a horizontal motor-driven shaft. After flocculation the water flows into the sedimentation tanks. Some small water-treatment plants combine coagulation and sedimentation in a single prefabricated steel unit called a solids-contact tank.
What is flocculation used for?
Coagulation and flocculation are used to separate the suspended solids portion from the water. Suspended particles vary in source, charge, particle size, shape, and density. Correct application of coagulation and flocculation depends upon these factors.
What is flocculation of soil?
Definition. Flocculation – process during which particles, for example, of a soil, dispersed in a solution contact and adhere each another, forming clusters, flocks, flakes, or clumps of a larger size. The term originates from the word “floc,” which is the flake of precipitate that comes out of solution.
What causes flocculation to occur?
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 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.
What is the best coagulant?
Chemical Coagulants Used In Water Treatment Aluminum Sulfate (Alum) – One of the most commonly used water treatment chemicals in the world. Aluminum Chloride – A second choice to Alum as it is more expensive, hazardous and corrosive. Polyaluminum Chloride (PAC) & Aluminum Chlorohydrate (ACH).
How is chloride removed from wastewater?
At high concentrations, chloride can harm fish and plant life. But there’s no easy and affordable way to remove chloride in wastewater. It would require reverse osmosis, the same process used to produce water for laboratory use, which is technically difficult as well as costly.
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 chemical is used for flocculation?
Coagulants such as alum (Al2(SO4)3-14H2O), iron salts (ferric chloride (FeCl36H2O), ferric sulfate (Fe2(SO4)3) and ferrous sulfate (FeSO47H2O)), lime (Ca(OH)2) and organic polyelectrolytes are used as flocculation aids during wastewater treatment.
What makes a good flocculant?
Polymers are useful as flocculants because they are robust molecules and sometimes carry charges. Because they are so large, small particles can get trapped in the curves of the polymer causing them to accumulate a mass heavy enough to prevent their retention in solution.
What do you mean by controlled flocculation?
Controlled flocculation (caused by additives): additive molecules cause the pigment particles to form a network; no direct pigment-pigment contact. Such “controlled” flocculates can be destroyed by low shear forces.
What is difference between flocculation and coagulation?
Coagulation: Particles that aggregate with themselves e.g. by the influence of a change in pH. Flocculation: Particles that aggregate by the use of polymers that binds them together. Coagulation and flocculation are well-known techniques within wastewater treatment.
What are the common coagulants?
The commonly used metal coagulants fall into two general categories: those based on aluminum and those based on iron. The aluminum coagulants include aluminum sulfate, aluminum chloride and sodium aluminate. The iron coagulants include ferric sulfate, ferrous sulfate, ferric chloride and ferric chloride sulfate.
What is difference between 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 flocculation degree?
Degree of flocculation (β) It is the ratio of the sedimentation volume of the. flocculated suspension ,F , to the sedimentation volume. of the deflocculated suspension, F∞ ß = F / F∞
Can chlorination remove impurities in water?
Chlorine will first react with inorganic impurities (dissolved iron, bromine, ammonia, etc.) before reacting with the organic compounds (dissolved organic material, bacteria, viruses, etc.). The iron precipitate, in its insoluble state, can be removed by filtration process within the water treatment centre.
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.
Is Redisperse difficult?
In a deflocculated system the dispersed particles remain as discrete units. Because the rate of sedimentation depends on the size of each unit, settling will be slow. The slow rate of settling prevents the entrapment of liquid within the sediment, which thus becomes compacted and can be very difficult to redisperse.
Why is flocculation important for treating water?
Coagulation and flocculation are both critical processes to separate and remove suspended solids in water and wastewater treatment. These processes improve the clarity of the water to reduce turbidity.
How does a coagulant work?
Coagulants work by creating a chemical reaction, eliminating negative charges that cause particles to repel each other. The action of these bubbles forces clots or flocs of particles to the water surface where they can be skimmed off. Dissolved air flotation is an alternative to sedimentation.
What is flocculation simple?
Definition. 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.
