Can you write the different ‘Coagulants’used for ‘Coagulation and Flocculation’?What is the relationship between ‘gpg and mg/l’? Why ‘Alkalinity’is needed in ‘Coagulationprocess’?How can you find the ‘Optimal Dose’and the ‘Best Coagulant’ for ‘Coagulation Process’? Discuss, compare and justify each part.

   Can you write the different ‘Coagulants’used for ‘Coagulation and Flocculation’?What is the relationship between ‘gpg and mg/l’? Why ‘Alkalinity’is needed in ‘Coagulationprocess’?How can you find the ‘Optimal Dose’and the ‘Best Coagulant’ for ‘Coagulation Process’? Discuss, compare and justify each part.                                                    

Answer:       

Coagulants:

1.     Organic Coagulants:

·        Polyamines

·        Melamine

·        Formaldehydes

·        Tannins

Inorganic Coagulants:

·        Aluminum Sulfate

·        Aluminum Chloride

·        Ferric Sulfate

·        Ferric chloride

Relationship:

1       gpg (grain per gallon) = 17.1 mg/l 

Alkaline particles improve the settlement of impurities: 

We can find the Optimal Dose and the Best Coagulant for Coagulation process through ‘Jar Test’.

·        Optimal Dose:

It is important to select the optimal coagulant dose because excessive coagulant overdosing can lead into high treatment cost and could be dangerous for health. In water treatment plant, optimal dose of coagulant is generally evaluated by Jar Test method.Limitation of this test is that it is time consuming, expensive, and the accuracy of results depends upon the experience of the plant operator.

·        Best Coagulant:

                         The choice of coagulant depends upon the types of suspended solid particle to be removed and also the coast of chemical. But the final section of the best coagulant is made by Jar Test method.