How Does Flocculation Work In Water Treatment

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 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 purpose of coagulation and flocculation in water treatment?

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.

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 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 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.

What are the 4 steps of water treatment?

These include: (1) Collection ; (2) Screening and Straining ; (3) Chemical Addition ; (4) Coagulation and Flocculation ; (5) Sedimentation and Clarification ; (6) Filtration ; (7) Disinfection ; (8) Storage ; (9) and finally Distribution. Let’s examine these steps in more detail.

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.

What are the 3 stages of water treatment?

The three stages of wastewater treatment are known as primary, secondary and tertiary. Each stage purifies water to a higher level.

How do flocculating agents work?

Flocculating agents are chemical additives that cause suspended solids to form aggregates called flocs. They act by shrinking the ionic double layer, or neutralizing the surface charge of suspended particles, or bridging between particles.

What is the most important step in water treatment?

It is, however, an important primary step in the water treatment process, because coagulation removes many of the particles, such as dissolved organic carbon, that make water difficult to disinfect. Because coagulation removes some of the dissolved substances, less chlorine must be added to disinfect the water.

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 first step in the water treatment process?

Coagulation and flocculation are often the first steps in water treatment. Chemicals with a positive charge are added to the water. The positive charge of these chemicals neutralizes the negative charge of dirt and other dissolved particles in the water.

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.

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.

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 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 primary treatment of water?

Primary treatment removes material that will either float or readily settle out by gravity. It includes the physical processes of screening, comminution, grit removal, and sedimentation.

What are the types of water treatment?

Processes

Chemical. Tanks with sand filters to remove precipitated iron (not working at the time)
Physical. Sedimentation for solids separation that is the removal of suspended solids trapped in the floc.
Physio-chemical.
Biological.
Desalination.
Portable Water Purification.
Boiler water treatment.
Cooling water treatment.

How is water treated steps?

Water treatment

Sedimentation – the water is stored in a large tank or a reservoir.
Filtration – the water is sprayed onto specially-prepared layers of sand and gravel.
Chlorination – chlorine gas is injected into the water to sterilise it.

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 are the three main stages of water treatment?

There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment.

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].

How is chloride removed from wastewater?

At high concentrations, chloride can harm fish and plant life. But there’s no easy and affordable way to remove chloride in wastewater. It would require reverse osmosis, the same process used to produce water for laboratory use, which is technically difficult as well as costly.

Why is flocculation important?

Used water can contain significant amounts of suspended particulate matter, which often takes long to sediment. Flocculation expedites sedimentation and ensures efficient solid/liquid separation.