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Flocculation is the process of formation of solid aggregates from small particles. Precipitation is the process of formation of an insoluble solid mass. The main difference between flocculation and precipitation is that flocculation forms floccules whereas precipitation forms precipitates.
What is the difference 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 do you mean by flocculation?
Flocculation is a two-step particle aggregation process in which a large number of small particles form a small number large flocs. Step 1: Coagulation. Small particles usually carry negative surface charges that hinder aggregation and settling (1a).
What is precipitation in water treatment?
Abstract. Chemical precipitation in water and wastewater treatment is the change in form of materials dissolved in water into solid particles. Chemical precipitation is used to remove ionic constituents from water by the addition of counter-ions to reduce the solubility.
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.
What precipitate is formed in Alum coagulation?
In this case, aluminum hydroxide (Al(OH)2) precipitates forming a “sweepfloc” that tends to capture suspended solids as it settles out of suspension. The pH of the water plays an important role when alum is used for coagulation because the solubility of the aluminum species in water is pH dependent.
What is precipitation in water cycle?
Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It is the primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth. Most precipitation falls as rain.
Why is coagulation and flocculation important?
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. Coagulation and flocculation occurs in successive steps, allowing particle collision and growth of floc.
What happens if agitation rate in flocculation phase is too high?
Stirring too fast can break large particles apart, while stirring too slowly can prevent particles from clumping enough. A wide variety of flocculation- mixing mechanisms have been used in water treatment.
What is precipitation and coagulation?
The process of precipitation/coagulation/flocculation transforms dissolved contaminants into insoluble solids, assisting in the contaminant’s subsequent removal from the liquid phase through sedimentation or filtration. The process usually uses pH adjustment, addition of a chemical precipitant and flocculation.
What is flocculation of soil?
Definition. Flocculation – process during which particles, for example, of a soil, dispersed in a solution contact and adhere each another, forming clusters, flocks, flakes, or clumps of a larger size. Flocculation is synonymous with agglomeration and coagulation.
What are the side effects of alum?
Side effects of Alum The excessive amount of alum intake may cause breathing difficulty, facial puffiness, pricking sensation & small ulcers on the skin, chest/throat tightness, and burns rarely seen in some cases.
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.
What is the most common form of solid precipitation?
Snow is the most common form of solid precipitation. Snow consists of particles of ice.
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.
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.
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.
What precipitation means?
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzling, rain, sleet, snow, ice pellets, graupel and hail. Short, intense periods of rain in scattered locations are called showers.
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 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 are precipitates used in everyday life?
Examples Of Precipitation Reaction In Everyday Life Precipitation reaction can be used in wastewater treatment. When a contaminant forms an insoluble solid, then we can use this reaction to precipitate out the contaminated ions.
What is the purpose 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 chemicals are flocculants?
A flocculants are usually organic chemicals added to wastewater to enhance flocculation, such chemicals are alum, aluminium chlorohydrate, aluminium sulphate etc.
What is flocculant for?
Used in a wide range of industries and applications, flocculants help to remove suspended solids from wastewater by aggregating contaminants into flakes or “flocs” that float to the surface of the water or settle at the bottom. They can also be used for lime softening, sludge thickening, and solids dehydration.
