Table of Contents
Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water.
What is water flocculation?
Flocculation is a water treatment process where solids form larger clusters, or flocs, to be removed from water. This process can happen spontaneously, or with the help of chemical agents. It is a common method of stormwater treatment, wastewater treatment, and in the purification of drinking water.
What is the purpose of flocculation in water purification?
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 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 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.
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 chemicals are flocculants?
A flocculants are usually organic chemicals added to wastewater to enhance flocculation, such chemicals are alum, aluminium chlorohydrate, aluminium sulphate etc.
How is flocculation done?
Surface chemistry 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.
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 is the purpose of flocculant?
Flocculants are substances that promote the agglomeration of fine particles present in a solution, creating a floc, which then floats to the surface (flotation) or settles to the bottom (sedimentation). This can then be more easily removed from the liquid.
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.
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 value?
The phenomenon of the precipitation of a colloidal solution by the addition of the excess of an electrolyte is called coagulation or flocculation. The minimum concentration of an electrolyte which is required to cause the coagulation or flocculation of a sol is known as flocculation value.
Is flocculation physical or chemical?
Flocculation, in physical chemistry, separation of solid particles from a liquid to form loose aggregations or soft flakes. These flocculates are easily disrupted, being held together only by a force analogous to the surface tension of a liquid.
What is meant by flocculation?
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. The process is in widespread use in many industrial applications.
Why is coagulant added to water?
Coagulant aid Chemicals (typically synthentic polymers) added to water to enhance the coagulation process. if an excess of alum is added so that the dosed water pH is less than 5.0, then the metal ions (Al3+) will directly ˜eutralize the negatively charged organic compounds and colloids in the raw water. 1.
Which gas is released when alum is added to water?
Explanation: Carbon dioxide gas is released when alum is added to water, which is corrosive to metals.
What happens when alum is added to water?
On contact with the water, the liquid alum forms a fluffy aluminum hydroxide precipitate called floc. Aluminum hydroxide (the principle ingredient of common antacids such as Maalox) binds with the phosphorus to form an aluminum phosphate compound.
Which are two chemicals used to purify water?
Chlorine and ozone are two chemicals used to purify water.
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.
Can you drink flocculant?
In addition, coagulants and flocculants are expensive, which is why you want to avoid adding more than are necessary to the water; drinking water treatment plants use “jar tests” to identify the optimal coagulant and flocculant concentrations. Do not drink any of your water samples—even if they appear clear.
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.
Does alum affect pH?
Ionic species present in alum solutions are highly dependent on the degree of reaction with hydroxyl ions. It is tempting to say that “the composition is pH-dependent.” However, in the vicinity of pH=4.3 the composition of alum solutions changes a great deal with very little change in pH.
Does pH affect coagulation?
Coagulation pH is an important factor that affects the enhanced coagulation. An on-line laser scatter instrument was used to record the development of floc sizes during the coagulation period. For PFSS, pH exerted great influence on floc growth rates but little influence on formed floc sizes.
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.
