Table of Contents
Is flocculation a chemical 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 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 is flocculation number?
Flocculation is a two-step particle aggregation process in which a large number of small particles form a small number large flocs. Step 1: Coagulation. Small particles usually carry negative surface charges that hinder aggregation and settling (1a).
What is flocculation a result of?
Flocculation (except in polymer science) Process of contact and adhesion whereby dispersed molecules or particles are held together by weak physical interactions ultimately leading to phase separation by the formation of precipitates of larger than colloidal size. Note 1: Agglomeration is a reversible process.
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.
What is the principle of flocculation?
Flocculation refers to the process used to bring the coagulated particles together so that they can combine to form larger, settleable, and filterable masses of particles called floc. Zeta potential is defined and its role in coagulation described.
What is the difference between flocculant and coagulant?
Coagulation is a chemical process. Flocculation is a physical process. Coagulants such as inorganic salts of aluminum or iron that neutralize the suspended particles are added during coagulation. Flocculant such as an organic polymer that involves in bridging and strengthening the flocs is added.
What two chemicals are commonly used as water coagulants?
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.
Is FeCl3 a coagulant?
Ferric chloride (FeCl3) is the most common iron salt used to achieve coagulation. Its reactions in the coagulation process are similar to those of alum, but its relative solubility and pH range differ significantly from those of alum. Both alum and ferric chloride can be used to generate inorganic polymeric coagulants.
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.
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.
How do you pick a flocculant?
How to choose flocculant? the molecular structure:the molecular structure of flocculant depends on the dewatering performance be required. the molecular weight::The choice of molecular weight depends on the types of dewatering equipment, and molecular weight are also said the length of the polymer chain.
What is the 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.
Is polymer a coagulant or flocculant?
Depending on the charge and chemical composition of your wastewater, flocculants can either be used on their own or in combination with coagulants. Flocculants differ from coagulants in that they are often polymers, whereas coagulants are typically salts.
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 are the side effects of alum?
If experienced, these tend to have a Severe expression i fluid accumulation around the eye. throat swelling. a feeling of throat tightness. a skin ulcer. hives. a shallow ulcer on the skin. fainting. puffy face from water retention.
What is the pH of alum?
Alum is most commonly delivered as a liquid concentration, having a solids level of 8.3% as Al2O3 or about 50% as hydrate. Alum solutions are acidic. For instance, a 1% solution has a pH of around 3. Ionic species present in alum solutions are highly dependent on the degree of reaction with hydroxyl ions.
Is alum positive or negative?
For example, the colloidal particles are negatively charged and alum is added as a coagulant to create positively charged ions. Once the repulsive charges have been neutralized (since opposite charges attract), van der Waals force will cause the particles to cling together (agglomerate) and form micro floc.
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 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.
What is the meaning of a flocculant?
flocculant. / (ˈflɒkjʊlənt) / noun. a substance added to a suspension to enhance aggregation of the suspended particles.
Is gypsum a flocculant?
Gypsum can coagulate or bridge clay particles, which accelerates settling. Flocculants should be used to prevent damage to sensitive water resources such as ponds, lakes and trout streams or whenever turbidity control is required. The best thing to do is a jar or bucket test using slightly varying rates of gypsum.
What is the best coagulant?
The best coagulant is therefore a pre-hydrolysed species with a high basicity. PACl has been found to be very suitable for lime softening applications.
What is flocculant and coagulant?
Coagulation and flocculation are two separate processes, used in succession, to overcome the forces stabilising the suspended particles. While coagulation neutralises the charges on the particles, flocculation enables them to bind together, making them bigger, so that they can be more easily separated from the liquid.
