1.0
Introduction and Objective
1.1
Introduction
Jar test is a small-scale test used for treatment of chemicals in water or waste water
treatment. It is used to treat excessive of turbidity and algal growth in water. It is also done by
varying the amount of treatment chemicals or also known as catalyst and other parameters
such as pH and mixing rate of the treatment. It stimulates the process of coagulation and
flocculation in real water treatment. The real purpose of this jar test is to help determining the
optimum amount of certain conditions to run a full-scale water treatment process.
Coagulation is a process where the destabilization of the given colloidal suspension or
solution is taking place. (Bratby, n.d.) The process is achieved through the use of appropriate
treatment chemicals, in which could be, aluminum or iron salts, which serves the process as
the coagulant agents. Flocculation, on the other hand, is referred to the induction of
destabilized particles in order to come together to make contact and hereby form large
agglomerates which can be separated easier by the pull of gravitational settings. (Coagulation
and Flocculation Process Fundamentals, n.d.) This process usually happens after
coagulation, the water with the charged colloids is then linked into the flocculation process
tank.
Turbidity is a measure of the degree to which the water loses its transparency due to
the presence of suspended particulates. (“Turbidity,” n.d.) As the total suspended solids in the
water increases, the murkier the sample will be which in the end resulted to high turbidity.
Thus, this turbidity is the main parameter to be analyse to determine purity of treated water.
In this experiment, three sets of test run are done to determine the optimum dosage
of coagulant, optimum dosage of flocculant and optimum pH level. From this data, the proper
coagulant and flocculant dosage needed in full-scale process could determine.
1.2
Objectives

To perform jar testing on the sample water

To determine the optimum coagulant dosage, flocculant dosage and pH value
for heavy metals removal in sample water

To determine the turbidity reduction of sample water after applying optimum operating
condition
2.0
Procedure
1)
1 litre of synthetic wastewater was filled up into 6 beakers.
2)
The pH and turbidity of the synthetic wastewater was checked and recorded.
3)
5 of the 6 beakers was injected with alum in an increasing order, means that every
beaker has more alum than the one before it, starting with 0.5 mL until 2.5 mL.
4)
Then, the 5 beakers that was injected with alum, was injected again with polymer
solution with the same amount into each beaker, which is 1.0 mL polymer.
5)
The sixth beaker was not injected with alum and polymer as the beaker is used for
comparison in the end of the experiment.
6)
The pH was remained consistent for every beaker.
7)
All the beakers was set into the jar test machine accordingly, and the machine was
switched on while the stirrer was set to 200 rpm for the duration of 1 minute.
8)
After that, the stirrer was slowed down to 20 rpm for 4 minutes.
9)
Next, the stirrer was stopped and the floc was let to settle down for 10 minutes.
10) Finally, all of the beakers was checked and recorded for their turbidity and pH.
11) Step 1 to 10 was repeated with the optimum alum dosage injected (the lowest
turbidity result) and constant pH for every beaker, except that the polymer solution
injected was in an increasing order, starting from 0.5 mL until 2.5 mL.
12) Step 1 to 10 was repeated again, with the optimum alum and polymer solution
dosage injected (the lowest turbidity result) for every beaker, except that the pH
was manipulated in an increasing order, starting from 5.45 until 9.17, by injecting
1% of NaOH and 1% of H2SO4 solutions into the beakers.
3.0
Result
Table 3.1: Set 1 readings for Optimum Coagulant Dosage
Jar
Coagulant
dosage
(ml)
Flocculants
dosage
(ml)
Initial pH
Final pH
Initial
turbidity
(NTU)
Final
turbidity
(NTU)
1
2
3
4
5
6 (Control)
0.5
1.0
1.5
2.0
2.5
0.0
1.0
1.0
1.0
1.0
1.0
0.0
7.74
7.20
7.74
6.83
7.74
6.66
7.74
6.49
7.74
6.19
7.74
7.74
293.00
293.00
293.00
293.00
293.00
293.00
77.00
47.70
33.20
21.60
5.32
249.00
Table 3.2: Set 2 readings for Optimum Flocculants Dosage
Jar
Coagulant
dosage
(ml)
Flocculants
dosage
(ml)
Initial pH
Final pH
Initial
turbidity
(NTU)
Final
turbidity
(NTU)
1
2
3
4
5
6 (Control)
2.5
2.5
2.5
2.5
2.5
0.0
0.5
1.0
1.5
2.0
2.5
0.0
7.74
6.41
7.74
6.31
7.74
6.13
7.74
6.01
7.74
5.94
7.74
6.71
293.00
293.00
293.00
293.00
293.00
293.00
6.77
3.67
3.55
4.18
3.35
281.00
Table 3.3: Set 3 readings for Optimum pH value
Jar
Coagulant
dosage
(ml)
Flocculants
dosage
(ml)
Initial pH
Final pH
Initial
turbidity
(NTU)
Final
turbidity
(NTU)
1
2
3
4
5
6 (Control)
2.5
2.5
2.5
2.5
2.5
0.0
2.5
2.5
2.5
2.5
2.5
0.0
5.45
4.10
6.68
5.10
7.38
5.48
8.57
5.80
9.17
6.00
7.74
7.30
293
293
293
293
293
293.00
3.88
5.69
9.89
21.3
11.1
293.00
Table 3.4: Optimum Experiment Condition
Coagulant Dosage (ml)
Flocculants Dosage (ml)
pH Value
Initial
Turbidity (NTU)
Final
Turbidity reduction (%)
4.0
2.50
2.50
5.45
293.00
3.88
98.68 %
Discussion
The main objective of this experiment is to determine the optimum operating
conditions; the coagulant dosage, flocculant dosage and pH value, for heavy metals
removal in sample water through jar test. Therefore, the percentage of turbidity reduction with
optimum operating conditions can be calculated.
In this experiment, four sets of jar test are conducted in order to determine the optimum
coagulant dosage, flocculant dosage and pH value for heavy metals removal in sample water.
The last set of jar test is to determine percentage of turbidity reduction under optimum
operating conditions which are determined from the previous sets of jar test. The first and
second set of jar testing varies the coagulant dosage and flocculant dosage being added to
each beaker respectively. Meanwhile, the third set of jar test varies the pH of each beaker by
either adding 1% H2SO4 solution to increase the acidity or 1% NaOH solution to increase the
alkalinity. The fourth set of jar test is injected with the amount of optimum chemical dosage
and optimum pH. However, none of the chemicals is added in Jar 6 as it sets as control in this
experiment. Moreover, for each set, the initial turbidity reading is taken for each jar; Jar 1, 2,
3, 4, 5 and 6. After adding the chemicals with the assigned dosage, and applying rapid and
slow mixing, the final turbidity is measured by using turbidity meter. The jar with lowest turbidity
reading means that the jar has been injected with optimum dose of coagulant or flocculant,
and has been set to the optimum pH.
Table 3.1, 3.2 and 3.3 displays that the raw water turbidity for every jar in each set is
293.00 NTU. From Table 3.1, the turbidity reduced to 249.00, 77.00, 47.70, 33.20, 21.60 and
5.32 NTU corresponding to 0, 0.5, 1.0, 1.5, 2.0 and 2.5 mL of 1% alum doses respectively.
The lowest turbidity measured is 5.32 NTU, from Jar 5 with 2.5 mL of 1% alum added.
Meanwhile, from Table 3.2, the turbidity reduced to 281.00, 6.77, 3.67, 3.55, 4.18 and 3.35
NTU corresponding to 0, 0.5, 1.0, 1.5, 2.0 and 2.5 mL of 1% polymer doses respectively. The
lowest turbidity reading recorded in Table 3.2 is 3.35 NTU which is also from Jar 5 with 5 mL
of 1% polymer dosage. Apart from that, Table 3.3 shows that turbidity reduced to 3.88, 5.69,
9.89, 21.3, 11.1, 293.00 NTU corresponding to pH of 5.45, 6.68, 7.38, 8.57, 9.17 and 7.74
respectively. The lowest turbidity measured is 3.88 NTU which is the pH of 5.45. In overall, it
is found that 2.5 mL is optimum dose for coagulant and flocculant along with pH 5.45 as the
optimum pH. This shows that a higher dose is not necessarily to get higher treatment
efficiency. Therefore, optimum operating condition is determined since low or over dosage
may reduce the efficiency of turbidity reduction. Besides that, Klimiuk et al. (1999) states that
coagulation performance increases as it goes toward more acidic. This is due to
hydroxocomplexes of a positive surface charged are formed. The negative hydrocomplexes
will be formed more as the hydroxyl ion concentration is high which it will provide great
electrokinetic attraction (Klimiuk et al., 1999).
Finally, as display from Table 3.4, the turbidity reduced to 3.38 NTU under optimum
coagulant and flocculant dosage, and optimum pH value. Table 3.4 also highlights the
percentage of turbidity reduction under stated optimum operating condition is 98.68 %.
However, from Table 3.3, the lowest turbidity after reduction is 3.35 NTU which is lower than
3.38 NTU under optimum operating condition. This is not align with the expectation as the final
turbidity under optimum operating condition is supposedly to reduce some more. Hence, there
is few error that may has occur while conducting the experiment.
The possible source of error may be the inaccuracy of pH readings during the last set
of jar test especially to Jar 1. This is because too much 1% NaOH solution has been added
until it reached pH 12, which later requires addition of 1% H2SO4 solution to set the pH below
6. Comparing to other jars, Jar 1 has slightly more chemicals being added which may become
of the factors that disturb the sedimentation process. Hence, the final turbidity measured is
slightly higher than what it is expected.
5.0
Conclusion and Recommendation
In conclusion, the optimal alum dosage needed to be injected into the synthetic
wastewater was 2.5 mL, while the lowest turbidity achieved after it settles down was 5.32 NTU.
Other than that, the favourable polymer solution dosage needed to be injected into the
synthetic wastewater was 2.5 mL and the lowest turbidity achieved by the wastewater was
3.35 NTU. Plus, the most suitable pH condition needed for the wastewater to achieve the
lowest turbidity was 5.45 and the turbidity value was 3.88 NTU. Finally, the percentage of
turbidity reduction under stated optimum operating condition was 98.68%.
For recommendation, in order to minimize the chance of errors occurring, a really small
syringe or a dropper must be used when injecting 1% NaOH and 1% H2SO4 into the
wastewater. This is because the pH of the wastewater can be easily changed by providing
even a small amount of the NaOH and H2SO4. Therefore, carefully injecting these solutions is
a way to control the changes of pH value.
6.0
References
Bratby, J. (n.d.). COAGULATION and FLOCCULATION With an emphasis on water and
wastewater treatment. Retrieved from https://www.ircwash.org/sites/default/files/25380CO-1277.pdf
Coagulation
and
Flocculation
Process
Fundamentals.
(n.d.).
Retrieved
from
https://www.mrwa.com/WaterWorksMnl/Chapter 12 Coagulation.pdf
Klimiuk, E., Filipkowska, U., & Korzeniowska, A. (1999). Effects of pH and coagulant dosage
on effectiveness of coagulation of reactive dyes from model wastewater by
polyaluminium chloride (PAC). Polish Journal of Environmental Studies, 8, 73-80
Turbidity. (n.d.). Retrieved March 14, 2019, from https://www.lenntech.com/turbidity.htm
7.0
Appendix
A. Sample of calculation
i.
Calculating turbidity reduction in percentage (%):
Initial tubidity − Final turbidity
× 100%
Initial turbidity
=
293 − 3.88
× 100% = 𝟗𝟖. 𝟔𝟖%
293
B. Laboratory Exercise
1) Why jar test must be done according to the condition of the real plant?
Because real plants or industrial activities are the main contributor to effluent
discharge into the river. Therefore, jar test needs to be done according to the
condition to these effluents discharged. By using the obtained optimal coagulant
dosage, flocculant dosage and pH, the best turbidity can be achieved whenever
treating the wastewater, according to their conditions.
2) Name few of the coagulants.
Organic Coagulants
Inorganic Coagulants

PolyAmines

Aluminum Sulfate (Alum)

PolyDADMACs

Aluminium Chloride

Melamine

Polyaluminum Chloride (PAC)

Formaldehydes

Aluminum Chlorohydrate (ACH)

Tannins

Ferric Sulfate
3) What is DOE (Department of Environment) Standard A and Standard B of Iron
according to Environmental Act of Malaysia (1974)?
Iron (Fe)
Standard A
Standard B
1.0 mg/L
5.0 mg/L
C. Jotter note