A jar test was done for ferric chloride (Table 1.0) and alum (Table 2.0) by vary

Question

A jar test was done for ferric chloride (Table 1.0) and alum (Table 2.0) by varying the
pH.
(i) Identify the optimum pH and describe the type of coagulation that will occur
at optimum pH.
(ii) Explain the highest turbidity observed for each coagulant.
Table 1.0 Jar test results for ferric chloride addition
Jar # 1 2 3 4 5 6
pH 5.5 6 6.5 7 7.5 8
FeCl3 (mg/L) 50 50 50 50 50 50
Turbidity (NTU) 40 10 15 20 22 23
Table 2.0 Jar test results for alum addition
Jar # 1 2 3 4 5 6
pH 5.5 6 6.5 7 7.5 8
Alum (mg/L) 50 50 50 50 50 50
Turbidity (NTU) 50 45 40 10 20 30

Explanation / Answer

(a)

In general , the pH value of coagulation value we treat water with alum should be ranging from 5.5 - 8 so from above question the optimum pH is 6.5

For addition of ferric salts the value should be ranging from5.5-11 so we can take it as for given question 7   

(b)

Turbidity purly depends on total disolved salts 40 and 50 for ferric chloride and alum respectively

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.