Table of Contents
The jar test involves exposing same volume samples of the water to be treated to different doses of the coagulant and then simultaneously mixing the samples at a constant rapid mixing time. The microfloc formed after coagulation further undergoes flocculation and is allowed to settle.
How does a coagulant work?
Coagulants work by creating a chemical reaction, eliminating negative charges that cause particles to repel each other. The action of these bubbles forces clots or flocs of particles to the water surface where they can be skimmed off. Dissolved air flotation is an alternative to sedimentation.
What is coagulation in jar test?
A laboratory procedure that simulates coagulation/flocculation with differing chemical doses. The purpose of the procedure is to estimate the minimum coagulant dose required to achieve certain water quality goals.
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.
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.
Is coagulation reversible?
Coagulation is irreversible, the proteins cannot be turned back into their liquid form.
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.
What is coagulant and give its function?
Water treatment coagulants are comprised of positively charged molecules that, when added to the water and mixed, accomplish this charge neutralization. Inorganic, organic, or a combination of both coagulant types are typically used to treat water for suspended solids removal.
What is the most commonly used coagulant in water treatment?
1. Alum (aluminum sulfate), Al2(SO4)3. Still, the most common coagulant in the United States, it is often used in conjunction with cationic polymers.
What is coagulant example?
Examples of primary coagulants are metallic salts, such as aluminum sulfate (referred to as alum), ferric sulfate, and ferric chloride. Cationic polymers may also be used as primary coagulants.
Is gypsum a flocculant?
Gypsum can coagulate or bridge clay particles, which accelerates settling. Flocculants should be used to prevent damage to sensitive water resources such as ponds, lakes and trout streams or whenever turbidity control is required. The best thing to do is a jar or bucket test using slightly varying rates of gypsum.
What are the similarities and differences between flocculation and coagulation?
Coagulation is a chemical process and flocculation is a physical process, In coagulation, the process involves the utilization of a coagulant that has the ability to destabilize the charged particles which are not settleable whilst flocculation involves a similar destabilization process that is achieved through Dec 10, 2017
What is jar test used for?
Jar test is a pilot-scale laboratory test that simulates coagulation or flocculation with differing chemical doses. The purpose of the jar test is to estimate the minimum coagulant dose required to achieve certain water quality goals.
What happens when coagulant is added to water?
Once added to water, the inorganic coagulants form aluminium or iron precipitates. These absorb impurities in the water as they fall, serving to clean the water. This process is known as the ‘sweep-floc’ mechanism.
How is jar test calculated?
0.1 gram and dissolve in 1000 ml distilled water. Calculate the volume of a 1 % Ferric Chloride solution that would be added to get the dosage required. A jar test indicates that the required amount of phosphorus removal can be achieved using a dosage of 3 ml of a 1% ferric chloride solution in a liter of wastewater.
What is meant by flocculant?
A flocculant is a compound or agent which is added to a vessel to make particles stick together and form larger particles. Flocculants are added to encourage floc formation and enhance settling and compression rates. Flocculation involves the addition of a flocculant that causes the particles to stick together.
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.
What is the most common used coagulant?
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 do you use flocculant?
How do you use a swimming pool flocculant? Turn on your filter. Again, you need a sand or DE filter to capture the large particles and recirculate your pool water. Balance the pH. Check other pool chemistry. Clean your pool filter. Add the flocculant. Run your pump for 2 hours. Let the pool sit for 8 hours. Vacuum your pool.
What are the two objectives of jar tests?
The objectives of the jar test experiment are to estimate the optimum concentration of aluminum sulfate for the removal of suspended matter and to investigate the change in alkalinity as a result of aluminum sulfate addition.
What makes a good coagulant?
The best coagulant is therefore a pre-hydrolysed species with a high basicity. PACl has been found to be very suitable for lime softening applications. The advantage of a low basicity coagulant is even more pronounced in full softening applications, and the non-sulphated PACl is the coagulant of choice.
What is coagulation process?
Coagulation is the chemical water treatment process used to remove solids from water, by manipulating electrostatic charges of particles suspended in water. This process introduces small, highly charged molecules into water to destabilize the charges on particles, colloids, or oily materials in suspension.
What are the common coagulants used?
The commonly used metal coagulants fall into two general categories: those based on aluminum and those based on iron. The aluminum coagulants include aluminum sulfate, aluminum chloride and sodium aluminate. The iron coagulants include ferric sulfate, ferrous sulfate, ferric chloride and ferric chloride sulfate.
Which coagulant is used in the jar test?
The following jar test procedure uses alum (aluminum sulfate) a chemical for coagula- tion/flocculation in water treatment, and a typical six-gang jar tester. The results of this procedure can help optimize the performance of the plant.
