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CE474 Lab 2 Spring 2014
JAR TEST
Coagulation and Flocculation
Josue Amigon
Date Due: March 31, 2014
Department of Civil Engineering at the City College(CCNY) of the
City University of New York.
Email: [email protected]
The City College of New York
140th Street & Convent Avenue
New York, New York 10031
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Contents
Table of Content Page No.
Abstract ... 3
1.0
Objective: .............. 3
2.0
Introduction .. 3
3.0Procedure .. 4
3.1 Detailed Procedure............ 4
3.2 Equipment and Materials.. 5
3.2 Analysis Procedure .. 5
4.0 Results 6
5.0 Conclusion . 8
6.0 References .. 9Appendix A 9
L ist of Tables
Table 1: Initial: pH, Alkalinity and Turbidity ... 6
Table 2: Final Data: pH, Alkalinity, and Turbidity .... 9
L ist of F iguresFigure 1: pH versus Alum dose .. .. 7Figure 2:
Alkalinity versus Alum dose ..... 7
Figure 3: Turbidity versus Alum dose .. 8
Abstract
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It is important to measure the turbidity of water because people
a certain level of
acceptance on how cloudy is the water and because there is some
standards for domestic water
supplies. The Jar Test simulates the coagulation, flocculation
and settling in one experiment todetermine the optimum dose to
reduce the turbidity to acceptable levels. The two most
commonly used coagulants are aluminum and ferric iron in this
experiment the aluminum
coagulant will be used. The water sample being test is composed
of tap water, clay and sodiumbicarbonate. The alkalinity and pH
were of main concern but after the test the results showedthey were
within the acceptable range. The residual turbidity curve was
plotted to determine the
optimum dose, and it was determined that the dose is 60 mg/mL of
alum coagulant to remove the
turbidity, color and bacteria. The type of source water will
have a large impact on how often jartests are performed.
1.0 Objective
The purpose of this experiment is to gain practical experience
in the laboratory,
strengthen the importance of testing parameters for waste and
determining the turbidity.
2.0 Introduction
Coagulation/flocculation is the process of binding small
particles in the water together
into larger, heavier clumps which settle out relatively quickly.
The larger particles are known as
floc. Properly formed floc will settle out of water quickly in
the sedimentation basin, removing
the majority of the water's turbidity. The assurance of water
quality is a critical part of the
engineers role in solving the problems of concern to people. The
interest in quality applies to
both the potable water supply, and wastewater management before
release into the environment.
Several parameters both physical and chemical can be used to
gauge water quality including
aesthetic properties (appearance, odor, taste), chemical profile
(acidity, alkalinity, and
presence/absence of chemical compounds as pollutants), and
concentrations of microorganisms.
Four of these metrics are of interest in this laboratory: the
chemical properties of pH and
alkalinity, and the physical parameters of turbidity.
Through a series of steps including filtration and coagulation
we can determine the
turbidity of the waste water sample. Turbidity is the cloudiness
of water due to colloidal
particles, and is measured by gauging interference to the
passage of light through the water. The
acidity of water is commonly expressed as the negative log of
the molar concentration of
hydrogen ions (H+), or pH, which can be easily measured with a
commercial meter. It is
measured in the laboratory through titration of the water in
question with a strong acid, using a
visual pH indicator to identify when the solution reaches a
certain acidity. The complete
processes for all tests conducted are discussed in the
Procedures section of this report.
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Measurement of wastewater quality is important not only in
finding the impact of release,
but in determining the efficiency of the treatment system. For
example, data can be collected
from both primary influent (raw wastewater) and effluent
(treated outflow) and compared to
determine the effect of the treatment process on a sample.
Although equivalent parameters are
not compared directly in this laboratory for influent and
effluent, a general comparison can be
made, particularly in aesthetic properties. The limits of
sensitivity of the equipment available in
the lab make direct comparison difficult given the limited scope
of this experiment.
The Procedure section of this report outlines the experimental
process for each test, and details
the analysis methodology. The Results and Discussion of this
report presents findings in tables
and figures.
3.0 Procedure
3.1 Detailed Procedure
The procedure of the experiment was given, and the experiment
was conducted by meand other students. The experiment was explained
to us byProfessor Vasil Diyamandoglu and
conducted at the Environmental Engineering Laboratory of the
City College of New York. One
sample water is being experimented which is composed of a
mixture of tap water, clay and
sodium bicarbonate. The Coagulant that is being used for this
experiment is an aluminum sulfate
known as Alum. The beakers are then filled will the waste water
sample of 1000 mL each. Thedose is assigned to each beaker to
obtain an optimum dose for an acceptable turbidity level. The
initial pH of the waste water sample is measured using a pH
meter. The initial alkalinity levelsare also measured by titration.
A 100 mL sample is placed in a beaker and put a few drops of
color indicator that will turn dark blue at first but as
theTitrant 0.02N H2SO4 is poured into the
beaker until the color changes into a light purple color then
stop and measure the amount of
titrant poured the color change means that the pH is at 4.3. The
Alum dose is poured into thebeakers which is mixed will the
stirrers. The samples are mixed at approx. 100 rpm for 1minute,
then decrease the speed to approx. 30 rpm and Allow the sample
to mix for a period of 10
minutes. Observe any changes in the suspended matte in the
sample. At the end of the mixing
period, turn off the stirrer, let the flocs settle (at least 20
minutes) and carefully remove the
supernatant from each beaker and determine the turbidity in each
of the samples with theturbidimeter. This type of meter does not
measure all of the deflected light, only that which is
deflected at a right angle (90 ) from the sample and light
source. Determine the pH of eachtreated water sample with the pH
meter. Also measure the final alkalinity of the treated sample
the same as before.
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3.2 Materials and Equipment1. Phipps & Bird Six-Place
Stirrer
2. 1 or 2-liter beakers
3. Aluminum sulfate (alum) solution
4.
Hach turbidimeter5. pH meter
6. Pipettes/syringes
7. Burettes
8. Erlenmeyer Flasks
9. 0.02 N H2SO4 titrant
10. Water sample
11. Volumetric flasks
12. Methyl orange (MO) indicator
13. Beakers
3.3 Analysis Procedure
Equations
Volume of Alum solution added to beakers
() ()
Alkalinity(as CaCO3mg/L), equivalent weight CaCO3= 50 mg/meq
( )
(2)
For the water sample being composed of tap water, clay and
sodium bicarbonate, a turbidity,
alkalinity and pH analysis will be conducted using the
procedure. Since many values are
required to find the parameters accurately a statistical
analysis is required. The mean and the
standard deviation would have to be calculated to find the best
solution. The volume of Alum to
be added to each beaker knowing the dose will be calculated
using equation 1. The pH will be
determined using a pH meter and the alkalinity will be
determined using equation 2. After the
final turbidity is found the residual turbidity will be plotted,
the pH will also be plotted and the
Alkalinity will also be plotted. Then the optimum dose for
turbidity will be determined from the
curve of the turbidity curve.
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4.0 Results
Table 1 shows the initial conditions of the raw water with its
initial pH, alkalinity, and turbidity,and taking their mean since
many values were calculated. Table 2 shows the final results
after
introducing the assigned Alum dose into each jar showing the
residual pH, alkalinity and
turbidity that is in appendix A. To better understand the
results they were plotted versus the
Alum dose. Figure 1 shows the pH of the sample water. The range
of adequate coagulation pH
is from 5 to 8 which is the within range of the pH curve, it is
also acceptable because as the alum
dose increases the pH of the sample should
decrease(Davis,pg274). Figure 2 shows the residual
alkalinity of the sample water and as shown the results are
acceptable because the alkalinity will
go down as the alum dose is increased. Figure 3 shows the
turbidity, and as seen it is difficult to
determine the optimum dose because the stages 1, 2, and 3 that a
turbidity curve has are
combined together, and you just see a small drop in turbidity
and then it rises, and goes into the
final stage 4 where it decreases. The optimum dose could be 60
mg/mL of alum.
Table 1: Initial pH, Turbidity and Alkalinity
Test No Alum dose Initial pH Initial Turbidity Initial
Alkalinity
Group1 0 7.76 45 150
Group2 0 7.99 40.4 150
Group3 0 8.22 40 140
Group4 0 7.96 41.5 138Group5 0 7.6 24 122
Group6 0 8.02 23 145.12
Mean 0 7.925 35.65 140.85
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Figure 1: Residual pH of the sample water
Figure 2: Residual Alkalinity of sample water
0
1
2
3
4
5
6
7
8
9
0 20 40 60 80 100 120 140
ResidualpH
Alum Dose(mg/mL)
pH
Acidity
0
20
40
60
80
100
120
140
160
0 20 40 60 80 100 120 140
ResidualAlkalinity(mg
/mL)
Alum Dose(mg/mL)
Alkalinity
Alkalinity
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Figure 3: Residual turbidity of water sample
5.0 ConclusionThe Jar test is an important method in finding the
optimum coagulant dose, we analyze
the residual turbidity, alkalinity, and pH of the water sample.
The Alum dose caused an increase
in particle size to increase the collision which is a complex
large precipitate known as flocs.This removes the turbidity, color
and bacteria which is important for drinking waters, during the
experiment small amounts of flocs formed, but it increased as
the dose increased(Davis, pg 271).
As given before the Alkalinity and the pH decreased as the alum
dose increased, which is a main
concern as an engineer. The consumption of alkalinity is the
result of alum addition, and wemust make sure there is residual
alkalinity in the water following the jar test. The optimum
dose
was determined to be 5 mg/mL of alum and a good option is to cut
out a section in between the60 mg/mL and do the test again with
smaller increments.
0
5
10
15
20
25
30
35
40
45
0 20 40 60 80 100 120
Residualturbidity(NTU)
Alum dose(mg/mL)
Turbidity
Turbidity
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6.0 References
(Davis)-Introduction to Environmental Engineering by Mackenzie
L. Davis and David A.Cornwell
Appendix A: Raw data
Table 1: Initial pH, Turbidity and Alkalinity
Test No Alum dose Initial pH Initial Turbidity Initial
Alkalinity
Group1 0 7.76 45 150
Group2 0 7.99 40.4 150
Group3 0 8.22 40 140
Group4 0 7.96 41.5 138
Group5 0 7.6 24 122
Group6 0 8.02 23 145.12
Mean 0 7.925 35.65 140.85
Table 2: Residual pH, Turbidity, and Alkalinity
Alum
Dose(mg/L)
Volume of
Alum
added(mL) Sample volume
Total Volume 0.2
H2SO4 Final pH
Final
Alkalinity
Final
Turbidity
0 0 100 14.5 8.06 145 40.72 0.2 100 13.9 7.53 139 32.9
5 0.5 100 13.7 7.2 137 28.3
6 0.6 100 13.4 7.64 134 32
8 0.8 100 12.6 7.3 126 37.2
10 1 100 12.2 7.35 122 41.5
10 1 100 13.7 7.84 137 36.7
12 1.2 100 13.1 7.65 131 32.6
15 1.5 100 13 7.61 130 31.3
20 2 100 12.8 7.57 128 24.4
25 2.5 100 12.3 7.46 123 2430 3 100 12 7.18 120 17.1
10 1 100 13.4 8.3 134 33.1
15 1.5 100 13 7.9 130 25.5
20 2 100 12.4 7.7 124 22.5
25 2.5 100 12.6 7.6 126 17.2
40 4 100 12.4 7.44 124 7.96
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60 6 100 11.6 7.24 116 2.47
40 4 100 10.1 7.42 101 14
50 5 100 9.8 7.28 98 8.48
60 6 100 9.2 7.24 92 5.56
70 7 100 8.8 7.22 88 5.12
80 8 100 8.4 7.05 84 5.09
90 9 100 7.8 7.04 78 4.66
5 0.5 100 11.2 7.56 112 23.5
15 1.5 100 10.6 7.37 106 19.1
30 3 100 10.25 7.34 102.5 11.6
60 6 100 8.7 6.98 87 3.29
90 9 100 7.9 6.95 79 2.2
120 12 100 6.8 6.62 68 1.95
5 0.5 80 9.7 7.61 121.25 10.9
8 0.8 80 9.4 7.53 117.5 9.88
12 1.2 80 9.3 7.47 116.25 6.96
15 1.5 80 8.9 7.41 111.25 6.43
20 2 80 8.5 7.38 106.25 6.04
25 2.5 80 8.4 7.2 105 3.22
