Which method comes before sedimentation?
Methods of plain sedimentation (i.e. horizontal, radial and inclined sedimentation) are preceded by a slow mixing process called flocculation.
What is flocculation and sedimentation?
In conventional coagulation-flocculation-sedimentation, a coagulant is added to the source water to create an attraction among the suspended particles. The mixture is slowly stirred to induce particles to clump together into “flocs.” The water is then moved into a quiet sedimentation basin to settle out the solids.
Is flocculation and sedimentation the same?
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.
What comes first flocculation or coagulation?
Coagulation and flocculation occurs in successive steps, allowing particle collision and growth of floc. This is then followed by sedimentation (see Sedimentation Chapter). If coagulation is incomplete, flocculation step will be unsuccessful, and if flocculation is incomplete, sedimentation will be unsuccessful.
What is flocculation in water treatment?
Flocculation is the separation of a solution, commonly the removal of sediment from a fluid. The term is derived from floc, which means flakes of material; and when a solution has been flocculated, the sediment has formed into larger aggregated flakes, making them easier to see and remove.
How does coagulation and flocculation work?
Coagulation and flocculation occur in successive steps intended to overcome the forces stabilising the suspended particles, allowing particle collision and growth of flocs, which then can be settled and removed (by sedimentation) or filtered out of the water.
What is flocculation process?
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.
Why is flocculation important?
Applying flocculation ensures a high flux over filtration units as well as efficient and cost effective separation of cell material from supernatant. Used water can contain significant amounts of suspended particulate matter, which often takes long to sediment.
Why is flocculation necessary for suspension?
Since the particles are linked together only loosely, they will not cake and may be easily redispersed by shaking the suspension. As we can see from Stoke’s Law, if we apply flocculation as a means of preventing caking, then we will increase the particle diameter, and thus increase the rate of sedimentation.
What is the process of flocculation?
4 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 the flocculation process?
How long does it take for flocculation to occur?
Once the floc has reached its optimum size and strength, the water is ready for the separation process ( sedimentation, floatation or filtration). Design contact times for flocculation range from 15 or 20 minutes to an hour or more. Flocculation mechanism scheme. Source: SNF FLOERGER (n.y.)
What is pre-sedimentation and how does it work?
Pre-sedimentation (pre-sed) is an effective water treatment method, often utilized with source waters that have high solids, turbidity, and/or organics during certain times of the year, such as spring runoff. The pre-sed process helps reduce these materials from the raw water to more acceptable levels.
What factors affect the rate of flocculation?
Other factors can influence flocculation including changes in pH, temperature, and the chemical medium. A from 6 to 8. Add a base colloid at pH 6 Floc at pH 8 Figure 3: Adjusting the pH leads to flocculation. Water treatment plants use various ways to flocculate the particles in water.
What is co-coagulation -flocculation?
Coagulation -flocculation is a chemical water treatment technique typically applied prior to sedimentation and filtration (e.g. rapid sand filtration) to enhance the ability of a treatment process to remove particles.