Table of Contents
Design contact times for flocculation range from 15 or 20 minutes to an hour or more, and flocculation requires careful attention to the mixing velocity and amount of mix energy. To prevent floc from tearing apart or shearing, the mixing velocity and energy are usually tapered off as the size of floc increases.
How do you remove flocculation?
After flocculation is complete, the large solid masses can be removed from the wastewater stream. This is done either through settling where the floc drops to the bottom for removal or through the use of filters which capture the floc in the filter material.
What does flocculation not remove?
Suspended particles cannot be removed completely by plain settling. Large, heavy particles settle out readily, but smaller and lighter particles settle very slowly or in some cases do not settle at all. Aluminum sulfate (alum) is the most common coagulant used for water purification.
What affects flocculation?
Several factors can affect flocculation, primarily poly- mer type, ionic strength, water pH, slurry solids, flocculant dilution, shear, molecular weight, and pro- cess conditions.
What strategies would you use to minimize particle flocculation?
Mixing intensity and shear optimization is a successful strategy to prevent floc breakage. Breaking flocs defeats the purpose of flocculation, increases filtration times, and should be avoided.
What is the importance 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.
Can you use too much flocculant?
Flocculant is aluminum sulfate, which is designed to clump with the particles you’re trying to remove. But if you add too much, the flocculant will start to agglomerate with itself instead of those particles. These flocculant clumps will not drop to the pool floor and can clog up your filter.
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.
What is the difference between flocculant and coagulant?
Flocculants differ from coagulants in that they are often polymers, whereas coagulants are typically salts. Generally speaking, anionic flocculants are used to catch mineral particles while cationic flocculants can capture organic particles.
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.
What chemical is used for flocculation?
Coagulants such as alum (Al2(SO4)3-14H2O), iron salts (ferric chloride (FeCl36H2O), ferric sulfate (Fe2(SO4)3) and ferrous sulfate (FeSO47H2O)), lime (Ca(OH)2) and organic polyelectrolytes are used as flocculation aids during wastewater treatment.
What is flocculant made of?
One of the most common flocculants used in water purification today is aluminum sulfate (also known as alum); its chemical composition is shown in Figure 3. Figure 3. The chemical structure of aluminum sulfate (alum). Aluminum sulfate is a white, solid (powder) with a chemical formula of Al2(SO4)3.
What is flocculation test?
A Flocculation Test Procedure is used to determine how much Flocculants need be added to solids in suspension (slurry or pulp) to cause the individual particles to collect in the form of flocs. Flocculation, i.e. aggregation through the use of long-chain organic polymers that bridge between adjoining particles.
What is the principle of flocculation?
Coagulation – flocculation is physico-chemical process that facilitates the agglomeration of fine particles (colloids) contained in water to form a floc that can be easily filtered from water. Effluent (waste water) must be treated before it is discharged or before the water is re-used.
Does flocculation increase particle size?
During the initial stage of flocculation primary particles form microflocs, such as doublets, triplets, etc. As the process continues these microflocs group into larger aggregates or macroflocs. For a given volume concentration the particle number concentration increases with decrease in particle size.
What can be the best method to coagulate a colloidal particle?
Coagulation is achieved by various mechanisms such as interparticle bridging, charge neutralization, ionic layer compression and sweep coagulation, which reduces the zeta potential and subsequently reduces the repulsive forces between colloidal particles.
What causes flocculation to occur?
In dispersed clay slurries, flocculation occurs after mechanical agitation ceases and the dispersed clay platelets spontaneously form flocs because of attractions between negative face charges and positive edge charges.
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 flocculating ion?
Coagulation or precipitation:-it is a process of aggregating together the colloidal particle so as to change them into large sized particles which ultimately settles as a precipitate. The ion which is responsible for neutralization of charge on the colloidal particles is called the coagulating ion or Flocculating ion.
Will rain mess up flocculant?
If it’s set to rain during the treatment postpone it. The rain hitting the water would be enough to disturb the process.
How long should flocculant sit?
Flocculant, although fast-acting, will still need around 8-16 hours to work its magic. It’s easiest to do this overnight.
How do I make my pool water crystal clear?
So the best way to have a crystal clear pool is prevention. Keep the chemical levels within the ideal ranges. Check the flow meter to be sure the pool is circulating water at a proper flow rate. Brush the walls and floor weekly. Keep a preventative amount of algaecide in the pool.
What are the side effects of alum?
If experienced, these tend to have a Severe expression i fluid accumulation around the eye. throat swelling. a feeling of throat tightness. a skin ulcer. hives. a shallow ulcer on the skin. fainting. puffy face from water retention.
Does alum increase 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.
How much alum do I put in my water?
Make an alum solution by adding 7.5 grams of alum to one liter of tap water.
