CIVIL ENGINEERING DEPARTMENT

WATER AND WASTE WATER ENGINEERING

LABORATORY

EXPERIMENT 1

“JAR TEST”

GROUP MEMBERS

NO NAME NO. MATRIX

1 AMIRUDDIN BIN NASHARUDDIN 14DKA13F1058

2 MUHAMMAD ZULFADHLI BIN NGADIRIN 14DKA13F1008

3 MUHAMMAD ANIFF BIN NASARRUDIN 14DKA12F2037

4 MUHAMMAD ARIFF AMIRUDDIN BIN ABD

RAHMAN

14DKA13F1004

5 ABDUL AZIM BIN ABDUL RAZAK 14DKA13F1014

OBJECTIVE

To determine the optimal coagulant does which will produce the highest

removal of a given water turbidity.

APPARATUS

1 Jar test apparatus with six rotating paddles blade

image

2 Six (6) beakers image

3 pH meter image

4 Turbidity meter image

5 Pipette image

REAGENT

1. Aluminium sulphate (alum) with a known concentration or anionic/cationic coagulant such as ferrous sulphate and ferric chloride.

THEORY

Raw water and waste water is normally turbid containing solid particles of

varying sizes. Particles with sizes greater than 50 µm settle fairly rapidly. The settling

velocities of colloidal particle of sizes less than 50 µm are very slow. Thus, these

particles are an courage to collide leading to coalescence of particle to from flocs

particles, which are bigger and heavier. These particle will higher setting velocities

and easily settle out. Colloidal particles do not agglomerate by itself due to the

presence of repulsive surface forces. A process is needed to suppress these forces

so as to allow flocs formation. This process is called coagulation process.

It is actually the addiction of chemical coagulant to the raw water or waste

water. Coagulant that are normally used are salts of aluminium namely aluminium

sulphate and ferric salts namely ferrous sulphate and ferric chloride. The next

process that follows the coagulation process is flocculation. It is the process that

promotes particles collision due to gentle agitation resulting in agglomeration of

smaller non-settle able particles into flocs (bigger particles) which settles easily to

produce clarified water. Addition of coagulant aid such as synthetic polymer will

accelerate settling.

PROCEDURES

1. Select any coagulant aid from the bench.

2. Prepare samples of waste water into six different beakers with one litre each

and label the beakers.

3. Add in coagulant aid with different dosage and one control sample.

4. Run the experiment.

5. Observe the result.

RESULT AND CALCULATION

JAR TEST 1 (Set the coagulant does)

Initial turbidity: 16 NTU

Initial pH: 8.34 23ºc

pH adjustment (base) : _______mg/L of _________

pH adjustment (acid) : _______mg/L of _________

Coagulant concentration : __________mg/L

Jar No 1 2 3 4 5 6

pH 7.96 7.63 7.43 7.18 6.98 8.05

Coagulant

dose (mg/L)

1 2 3 4 5 Control

Agitate

(minute)

10 10 10 10 10 None

Fast (rpm) 40 40 40 40 40 None

Slow (rpm) - - - - - None

Setting depth

(mm)

1.7 2.1 2.8 3.5 4 1

Turbidity

(NTU)

1 1 11 0 2 21

Floc formation

(final 10

minutes)

Size

B

Size

C

Size

D

Size

E

Size

F

Size

A

Floc formation can be recorded by referring to the measurement scale as depicted in figure 1.

Figure 1 : Scale for measurement of floc sizes

DATA ANALYSIS

1. Compare the level of turbidity in each sample.

2. With the aid of a graph, show the relationship between pH and turbidity with respect to coagulant dosage.

3. From the graph, get the optimum value for pH and coagulant dose of the coagulation process.

4. Explain the implication of using different dosage of aluminium sulphate in the treatment process.

DISCUSSION

1. By using aluminium sulphate, the mechanism is:

Al³ + 3H2O Al(OH)3 + 3H

2. How the coagulant works?

3. Name three types of acid and base which are suitable for pH neutralization.

4. What the benefits of using coagulant aids?

5. In what way the dosage of aluminium sulphate in the treatment process can be reduced?

6. Instead of Al2(SO4)3, name another three coagulant that can be best used as coagulant aid.

CONCLUSION