Table of Contents
Flocculation is a physical process in which the fine solids produced by coagulation are brought together into larger particles using controlled low levels of shear. This may be done in either static (Fig. 7.1) or dynamic mixers. Figure 7.1.
What is chemical flocculation?
In colloid chemistry, flocculation refers to the process by which fine particulates are caused to clump together into a floc. The floc may then float to the top of the liquid (creaming), settle to the bottom of the liquid (sedimentation), or be readily filtered from the liquid.
What is the process of 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.
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.
Why alum is used in wastewater treatment?
Iron free Aluminum Sulfate (Alum) is most widely used in municipal drinking water and wastewater treatment systems. In potable water applications, alum functions as an excellent primary coagulant. Through charge neutralization and flocculation in raw water, alum removes: Turbidity.
What is the principle of coagulation?
Coagulation and flocculation are related terms describing the process of preparing colloidal materials for removing by sedimentation. Coagulation is the process used to reduce the energy forces present around particles that tend to keep them from joining together to form a larger mass.
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.
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 are the chemicals used for coagulation?
Traditional chemical coagulation uses aluminum and iron coagulants. The most common aluminum coagulants are aluminum sulfate, aluminum chloride, and sodium aluminate. Iron coagulants include ferric sulfate, ferrous sulfate, ferric chloride, and ferric chloride sulfate [4].
Can you add too much flocculant?
Adding too much flocculant can cause its own issues. Flocculant is aluminum sulfate, which is designed to clump with the particles you’re trying to remove. But if you add too much, the flocculant will start to agglomerate with itself instead of those particles.
What are the side effects of alum?
Side effects of Alum The excessive amount of alum intake may cause breathing difficulty, facial puffiness, pricking sensation & small ulcers on the skin, chest/throat tightness, and burns rarely seen in some cases.
What is coagulant and flocculant?
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. Coagulation and flocculation occurs in successive steps, allowing particle collision and growth of floc.
How do you make a flocculant solution?
Prepare your coagulant–flocculant solution by adding one quarter teaspoon of alum powder to about three teaspoons of tap water. (You might have to heat the solution in the microwave to get the powder dissolved.) Stir the solution until all the alum powder is dissolved.
What is flocculation reaction?
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).
Does flocculant affect pH?
Because flocculants can affect the pH level, you’ll want to start out with it at about 7.0 so you can make sure your sanitizer keeps working at maximum efficiency.
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)
Is flocculant harmful to humans?
Corrosive Product, contact with eyes or skin can cause burns; ingestion or inhalation can cause internal damage, if this occurs immediate medical assistance is required. Contact with skin: irritation. Contact with eyes: irritation. Swallowing: irritation to mucosal and digestive tract corrosion.
How fast does flocculant work?
How Long Does It Take to Work? The beauty of flocculants is that they work fast. Your pool can be cleaned in 24 hours, whereas with a clarifier, it takes a few days for the filter to do its job. The drawback, however, is that you have to vacuum the dirt out from the pool floor by yourself.
Is Salt a flocculant?
5.1. Inorganic salts of multivalent metals are effective flocculants. The multivalent metal cations in these salts neutralize the cell surface charge and bridge cells together to facilitate flocculation [15, 66].
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.
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. Flocculation is synonymous with agglomeration and coagulation.
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.
Why does pH affect coagulation?
Since pH values affect the surface charges and forms of the coagulants and impurities to be removed, controlling the level of pH would significantly improve the coagulation process. Therefore, not only coagulant dosage, but also pH value should be optimized to maximize the removal of impurities present in raw water.
Is coagulation a chemical process?
Coagulation is a chemical process that involves neutralization of charge whereas flocculation is a physical process and does not involve neutralization of charge.
Does flocculant kill algae?
There are two major chemical treatments for algae: flocculant and chlorine. Flocculant, or floc, is a chemical and mechanical process that works fast but requires work on your part. Then, you must turn it off to give the algae time to settle. If you use chlorine shock, you should run the filter almost continuously.
