Table of Contents
In water treatment, coagulants are used to remove a wide variety of hazardous materials from water, ranging from organic matter and pathogens, to inorganics and toxic materials, like arsenic, chemical phosphorous and fluoride.
What is the purpose of coagulation?
Coagulation is a process used to neutralise charges and form a gelatinous mass to trap (or bridge) particles thus forming a mass large enough to settle or be trapped in the filter.
What is coagulant and give its function?
Coagulants are a substance which cause particles in a liquid to curdle and clot together. Particles stay suspended in water rather than settling because they carry surface electrical charges that mutually repel each other.
What is the process of coagulation in water?
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.
What is natural coagulant?
Natural coagulant is a naturally occurred; plants based coagulant that can be used in coagulation-flocculation process of wastewater treatment for reducing turbidity.
What are the characteristics of good coagulant?
There are three key properties of a coagulant :
- Trivalent cation : As indicated in the last section, the colloids most commonly found in natural waters are negatively charged, hence a cation is required to neutralize the charge.
- Nontoxic : This requirement is obvious for the production of a safe water.
What are the types of anticoagulants?
There are three main types of anticoagulant medications:
- Vitamin K antagonists.
- Direct Oral Anticoagulants (DOACs)
- Low molecular weight heparins (LMWH)
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 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 are the types of coagulation?
Types of coagulation tests
- Complete blood count (CBC) Your doctor may order a complete blood count (CBC) as part of your routine physical.
- Factor V assay. This test measures Factor V, a substance involved in clotting.
- Fibrinogen level.
- Prothrombin time (PT or PT-INR)
- Platelet count.
- Thrombin time.
- Bleeding time.
What are the factors affecting coagulation?
Many factors effect of colloidal matter such as, nature of coagulant, retention time, concentration of coagulant and the physical properties such as temperature, pH and others.
Which one is a good coagulant?
Aluminum and iron salts are the most commonly used inorganic coagulants in the wastewater treatment settings. These include based aluminum metals (aluminum chloride, aluminum sulfate, sodium aluminate) and iron based metals (ferrous sulfate, ferric sulfate, ferric chloride) [13, 17, 18].
What are the common coagulants used?
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.
Why alum is used as coagulant?
When alum is added to water, it reacts with the water and results in positively charged ions. Coagulation removes colloids and suspended solids from the water. These particles have a negative charge, so the positively charged coagulant chemicals neutralize them during coagulation.
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.
What is coagulant made of?
The most common coagulants are salts of aluminum or trivalent iron, with aluminum being more commonly used.
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 much coagulant is added?
Typical coagulant dosage ranges from 0.5 to 20 ppm. Inorganic coagulants generally require a higher dose than polymeric coagulants. The best technique for determining the proper dosage of coagulant is to feed the product in-line and measure the SDI in the filter effluent as a function of coagulation feed rate.
What is meant by coagulation of water?
In coagulation, we add a chemical such as alum which produces positive charges to neutralize the negative charges on the particles. The coagulation process involves the addition of the chemical (e.g. alum) and then a rapid mixing to dissolve the chemical and distribute it evenly throughout the water.
What is coagulant explain with example?
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.
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.
How does pH value affect coagulation process?
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 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 is a coagulant medication?
Coagulation modifiers are drugs that act on the blood coagulation pathway in different places to prevent or promote blood clot formation. Anticoagulants and antiplatelet drugs are used to prevent blood clot formation.
