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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 chemical is used for flocculation?
Aluminum sulfate or alum (Al2(SO4)3), ferric chloride (FeCl3) and ferric sulfate (Fe(SO4)3) are the most widely used flocculants [1, 70]. These flocculants have a long history of use in removing colloidal particles from water and wastewater [15, 17].
What is added during coagulation in water treatment process?
The coagulation process involves adding iron or aluminum salts, such as aluminum sulphate, ferric sulphate, ferric chloride or polymers, to the water. These chemicals are called coagulants, and have a positive charge. The larger particles, or floc, are heavy and quickly settle to the bottom of the water supply.
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.
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 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 is the difference between flocculant and coagulant?
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 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.
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 effect 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.
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.
What does flocculant water do?
Flocculants improve filtration, leading to an improved cleaning and disinfection of the water. It is the process in which all of the smallest particles that aren’t visible to the naked eye clump together into a big enough group that they can then be removed from your water by the filter.
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.
What chemicals are used in 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].
What are the similarities and differences between flocculation and coagulation?
Flocculation is synonymous with agglomeration and coagulation / coalescence. Basically, coagulation is a process of addition of coagulant to destabilize a stabilized charged particle. Meanwhile, flocculation is a mixing technique that promotes agglomeration and assists in the settling of particles.
What is the most used coagulant?
Iron and aluminium salts are the most widely used coagulants but salts of other metals such as titanium and zirconium have been found to be highly effective as well.
Does alum kill germs in water?
Alum precipitates the insoluble materials in the water and kills or lowers the total bacterial content of the water.
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.
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 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 chemicals are used to treat water?
The most commonly used chemicals for water treatment process are:
- Algicide.
- Chlorine.
- Chlorine dioxide.
- Muriatic acid.
- Soda ash or Sodium bicarbonate.
Is polymer a coagulant or flocculant?
Polymers (long-chained, high-molecular-weight, organic chemicals) are becoming more widely used. These can be used as coagulant aids along with the regular inorganic coagulants. Anionic (negatively charged) polymers are often used with metal coagulants.
Which coagulant is best?
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 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.
Which are two chemicals used to purify water?
Chlorine and ozone are two chemicals used to purify water.
