cel-report

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Faculty of Engineering
School of Chemical and Environmental Engineering
H83CEL- Chemical Engineering Laboratory
Flocculation
Supervisor:
Dr. Chong Mei Fong
Prepared by:
Adnaan Abbas Malak
UNIMKL-012117
Group Members:
Jack Maxwell
Low minh ge
Ong sze yinh
Khiarul Aamir

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Table of Contents
1. SUMMARY.............................................................................................................................................3
2. SAFETY ASSESMENT ..............................................................................................................................4
3. INTRODUCTION.....................................................................................................................................6
4. AIMS AND OBJECTIVES......................................................................................................................7
5. LITERATURE REVIEW.........................................................................................................................8
5.1 Principles of flocculation and coagulation:.......................................................................................8
....................................................................................................................... Error! Bookmark not defined.
5.2 Factors affecting Coagulation and flocculation: .............................................................................10
Comments: the data obtained from the literature uses waste water of different contents, with
experiment repeated more than ................................................................................................................13
5.3 Use of PACl as effective coagulant:.................................................................................................13
6. EXPERIMENTAL PLANNING & DEVELOPMENT................................................................................18
7. METHODS........................................................................................................................................20
7.1 MATERIALS & APPRATUS REQUIRED: .............................................................................................20
7.2 PREPARATION OF RAW WATER: .....................................................................................................21
7.3 Preparation of 1 M Ca (OH)2 Solution: ...........................................................................................21
7.4 Preparation of 0.15 M Polyaluminium Chloride: ............................................................................22
7.5 Experimental Procedures................................................................................................................23
7.5.1 Set 1: Variation of PAC dosage....................................................................................................23
7.5.2 Set 2: Variation of pH (optimum dosage of PAC)........................................................................23
7.5.3 Set 3: Variation of settling time ..................................................................................................24
7.5.4 Set 4: Variation of stirring speed ................................................................................................24
7.6 TESTING METHODS:........................................................................................................................25
8. RESULTS & DISCUSSION:.....................................................................................................................28
9. ERRORS AND UNCERTANITIES: ...........................................................................................................37
10. Conclusion, recommendation and future works ............................................................................39
11. REFERENCES....................................................................................................................................40
12. APPENDIX:.......................................................................................................................................44

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1. SUMMARY
This Lab report is compiled to carry out the study of the efficient removal of
turbidity, color, aluminum, and TSS from river water by varying coagulant dosage,
pH , settling time and stirring speed of the flocculator. An optimum dosage of
0.1mL of PACl was selected with optimum pH 7.12 , settling time as 1.5 hrs and
optimum stirring speed of 250 RPM. Lovibond flocculator along with HACH
spectrophotometer and colorimeter were used in the experiment. A literature
review was also conducted to compare the experimental results with that of
literature. Experimental results obtained for pH and coagulant dosage don’t
agree with the literature study. Also the results obtained for stirring speed and
settling time agrees with the theory stated in literature review and further details
are discussed in section 8 and 9 of the report. Finally errors and uncertainties
experienced during the experiment were discussed; along with recommendation
and future works so that to improve our results the next time when this
experiment is performed.

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2. SAFETY ASSESMENT
Hazard and Operability Study Report
Project Title HAZOP FOR JAR TEST
Line of Study Flocculator and experimental procedure
Study Team
Process
Parameter
Guideword Deviation Likelihood
Ranking
(Low=1-
High =5)
Possible
Causes
Consequences Action
required
Safeguard Recomm
endatio-
n
Impeller
Speed
High High Speed 4 Malfunction
of
controller
Scratches in
beaker
Breakage of
beaker
Overflow of
liquid
Breakage of
impeller
Turn off
and re-
calibrate
controller
Check
calibration
every few
months
Write
calibrati-
on
procedu-
re
Low Low Speed 3 Malfunction
of
controller
Insufficient
mixing
Turn off
and re-
calibrate
controller
Check
calibration
every few
months
Write
calibrat-
ion
procedu-
re
Sample
level
High High level 3 Raw water
container
opening too
large
Overflow of
fluid
Corrosive
materials spill
Beaker
becomes too
heavy to
move
Liquid on floor
causing
slipping
Clean
surfaces
Use
chemical
for
cleaning if
solution is
acidic
Use a
funnel
More
people
controlling
the tilt of
the
container
Wear PPE
at all
times
Use of
smaller
raw
water
Containe
-rs
Smaller
opening
on
containe
-r

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Lime
preparation
heat
High High
temperature
4 Too much
solid added
Breakage of
beaker due to
rapid
temperature
change
Injury due to
burning
Set vessel
down and
leave to
cool
Use
emergency
shower if
skin
contact is
made
Wear PPE
Do not
hold
beaker
Measure
amount of
reagent
required
before
addition
Use
alternati
ve
material
Use
thicker
reaction
vessel
Lime liquid
level
High High level 4 Too much
liquid
added
Overflow of
hazardous
material
Spillage
causing
corrosion
Slipping due
to wet
surfaces
Clean
spillage
Use
chemicals
to
neutralize
Use
emergency
shower if
skin
contact is
made
Wear PPE
Monitor
filling
Use a
funnel
Prepare
over a
sink
Larger
vessel
opening
Aim to
fill vessel
to lower
height

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3. INTRODUCTION
Water is a major essential to sustain life. Hence, a satisfactory constant supply of
adequate, safe and accessible must be available to everyone. It is very essential to
improving access to safe drinking-water as it can result in tangible benefits to
health and social welfare. Every effort should be made to achieve a drinking-
water quality as safe as possible. The raw water is collected from Sungai Sering
Ulu Kelang. The composition of the water is shown in Table 4 under section 8 of
the report. in addition to the contents mentioned in table 4, waste water also
contains NOM (Natural organic material) which is derived from decaying organic
matter and dead organisms and can impart color, taste and odour to the water (Yi
Geng, 2005).
The important aspect of water and wastewater treatment process is the
coagulation and flocculation process which is widely used due to its simplicity and
cost effectiveness. This process is carried out because surface water generally
contains a wide variety of colloidal particles that may impart turbidity and color to
the water (Benefield et al., 1982). These particles are very small to be settled by
gravity or to be filtered through common filtration media. In addition, colloidal
suspension is quite stable in surface water due to its electrical surface charge (Yi
Geng, 2005) for this reason coagulants are used to destabilize the colloidal
particles and carry out the separation. The principles of coagulation and
flocculation are discussed in detail in section 5. The purpose of the experiment is
efficient removal of turbidity, aluminum, color and TSS (Total Suspended solids)
by changing the parameters which are pH, coagulant dosage, settling time and
stirring speed of lovibond flocculator. The lovibond flocculator consists of 6
impellers or spindles which are cleaned before and after every experiment. The
coagulant used is PACl (polyaluminium chloride) and the equipment used to
perform turbidity, color, aluminum and TSS test are HACH spectrophotometer
and a colorimeter.

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4. AIMS AND OBJECTIVES
The objective of the experiment is to investigate the removal efficiency of total
suspended solid, color intensity, turbidity and aluminum content by varying the
following parameters in the production of drinking water:
 Coagulant dosage
 pH value
 settling time
 stirring speed
The target of the experiment is to fulfill the standard of drinking water as below:
 Total suspended solid : 90 mg/l
 Color intensity :15 TCU; where 1 TCU=1 PtCo
 Turbidity : 5 NTU ; where 1 NTU = 1 FAU
 Aluminum content : 0.2mg/l
 pH level : 6.5-9.0
The following data for Color, Turbidity, Aluminum content and pH level is taken
from (Ministry of Health Malaysia, 2010). The value for TSS (Total Suspended
Solid) is taken from using Utah’s standard (US EPA office of water, 2003).

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5. LITERATURE REVIEW
The purpose of the literature review is to present an overview of the concept and
principle of coagulation and flocculation processes. Certain important factors
affecting coagulation and flocculation are discussed in detailed in this section.
Also a detailed study on PACl used as a coagulant in water treatment is also
discussed here.
5.1 Principles of flocculation and coagulation:
Coagulation is the “electrochemical process of aggregating small particles into
larger particles or flocs that settle rapidly due to increased weight. In this process
coagulants are added to turbid water in order to destabilize particles and reduce
the repulsion forces. Destabilization increases the tendency of particles to
coalesce, resulting in heavier agglomerated particles. The heavier particle then
settles out of solution. Whereas flocculation refers to the process by this
destabilized particles actually conglomerate into larger aggregates so that they
can be separated from the waste water.
In simple terms flocculation is a physical process of prompting particle contacts to
enhance aggregation for destabilized particles. This physical process of collisions
between destabilized particles, in flocculation units are achieved by three
separate mechanisms (Weber, 1972):
 Brownian diffusion or perikinetic flocculation due to the continuous
bombardment by surrounding water molecules
 Fluid shear or orthokinetic flocculation due to velocity differences or
gradients in either laminar or turbulent fluid fields
 Differential sedimentation due to gravities of particles, as faster settling
particles overtake and collide with slower settling particles.
This mechanism of flocculation depends on the size of the particles present in
suspension. Perikinetic flocculation or fluid share dominates the latter when
particles are approximately of 1um and it promotes further aggregation by stirring

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and settling (Benefield et al., 1982). Further details on stirring speed (fluid share)
and sedimentation is discussed later in the report.
One of the common theories for coagulation used is charge neutralization where
the flocculant and the adsorption site are of opposite sites which leads to
neutralization. In most cases, hydrophobic colloidal particles in waste water are
negatively charged and thus inorganic flocculants and cationic poly-electrolytes
are preferable. The flocculation could occur simply as a result of reduced
charged at surface and hence a decreased electrical force between colloidal
particles, which allows the formation of van der wall forces between colloidal and
fine suspended materials to form microfloc (Chong, john robinson and chai siah
lee).
A jar test is carried out which is a common laboratory coagulation test. Before
treatment can begin a coagulant must be first selected. The selection of coagulant
is further discussed in detail in this section. Use of lime is also encouraged in
some of the jar test to maintain the pH at approximately 7.0. If the waste water is
acidic the lime addition which is Ca (OH) 2 leads towards neutralization of acid
before colloid removal can take place. A bench-scale jar test is used containing a
series of standard beakers and a stirrer for mixing. The purpose of a jar test is to
determine optimal pH, coagulant dosage, stirring speed and settling time.

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Figure 1: Picture of Levibond flocculator
5.2 Factors affecting Coagulation and flocculation:
Alkalinity/pH: Alkalinity is the acid neutralizing capacity of water, and is a general
indication of water’s buffering capacity (D.J.Pernitsky, 2003). The salts used for
coagulation form certain ions in solution that are responsible for coagulation
process. But however the ions produced depend upon the pH of the water
sample. pH that is too low may not allow the coagulation process to proceed
while high pH can cause coagulated particles to disperse (ROSEMOUNT Analytical,
2009) .
Hatfield found the optimum pH range for color removal to be 6.1 to 6.3, but it
worth to be noted that the value for maximum floc formations depends upon the
anion present in the solution, such as SO42-, Cl-, etc. (Hatfield, W.D., J Am 6
Water Works Assoc, 11, 554 (1924)).
In another document the functionality of coagulation has been found to reduce
after a pH in the region 7-9 (Greville, 1997; Uyak and Toroz 2007; Al Mubaddal et
al. 2009, Dwyer et al., 2009).
From (G.Seyrig and W.Shan , 2007) we can see on those graphs that the pH which
allows the best either color and turbidity removal is around 6.5. At this pH the
color removal is more than 76% when the turbidity removal is around 73%.

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However according to Malaysian standards the pH for a drinking water should be
in the range of 6.5-9.0.
Coagulant Dosage: There is a range of optimum dosages for a coagulant at which
maximum settling and removal of suspended particles is most efficiently and
effectively achieved. Below this range will destabilize the particles. Above this
range the coagulant serves as a chemical coating of the colloids which in turn re-
stabilizes the particles (KIM LUU, 2000) .In water treatment practice the required
coagulant dose generally falls within the range 2-8 mg·L-1 as metal ion. In
wastewater treatment practice coagulant concentrations up to 40 mg·L-1 (as
metal ion) have been used (Casey 1997). So the coagulant dose really depends on
the required treatment extent and the purpose of treatment.
From (G.Seyrig and W.Shan , 2007) The decreasing of the river water color seems
to be the more efficient (with a bit less than 80% removal) with a higher alum
concentration ranging between 120 and 200 mg/L.
Though different literature states different optimum dosage value but optimal
coagulant dosage is highly related to source of raw water used. Therefore it has to
be determined experimentally by reducing turbidity, color, aluminum content and
TSS.
Stirring speed and settling time: Once the flocks are made then it all comes to
the factors effecting sedimentation. One of the factors involved is the degree of
agitation of the suspension. Gentle stirring may lead to accelerated settling if the
suspension behaves as non-Newtonian fluid in which the apparent viscosity is a
function of the rate of shear. The change in viscosity can probably be attributed to
the re-orientation of the particles (Coulson and Richardson, Vol 3). Mixing or
stirring disperses precipitating agents, coagulant and coagulant aids throughout
the wastewater to ensure rapid reaction and settling of precipitates possible. The
extent to which mixing or stirring can be done depends on number of factors like:
amount of energy supplied, mixing residence time and turbulence effect which in
turn depends on size and shape of mixing tanks. There are two types of mixing

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rapid or flash. The main objective is to mix one substance completely into
another. ( Aquacultural engineering, 2002)
Also stated in (Aquacultural engineering,2002) that the lower mixing speed may
improve the removal of turbidity at low concentrations due to reduced shearing
of the floc during initial formation. Also at high stirring speeds velocity gradients
tend to be high which in turn promotes particle contacts for aggregation (Yi Heng,
2005).
For settling time after the coagulation process is done then it depends upon the
sedimentation rate of the particles and also the velocity gradients existing in the
fluid which can affect the velocity of settling particles. If the process is at steady
state particles will settle quickly and there will be only minor changes for
prolonged settling time (Coulson and Richardson).
Turbidity: It is caused by suspended colloidal particles, such as slit, clay
microscopic organisms, soluble colored organic compounds, finely divided organic
or inorganic matter (Benefield et al, 1982). Higher turbidity water containing
higher amount of particles generally requires higher dosages of coagulant. It is
one of the most commonly used parameters for the testing of drinking water
quality. As the number of particles increase a higher intensity of light is scattered
and a higher turbidity value is obtained. The European standards do not appear
to address turbidity, however, the World Health Organization, establishes that the
turbidity of drinking water should not be more than 5 NTU, and should ideally be
below 1 NTU (LENNTECH, 1998-2015). Malaysian drinking water standards state a
maximum value of 5 NTU.
Color: It can be caused by any suspended particle in waste water. But according
to (Beneield, 1982) it is caused by colloidal forms of iron and manganese or more
commonly by NOM. According to (A.S.Greville, 1997) The choice of chemicals
must be one that will create a water in which the color will be least stable (usually
at a pH between 5.5 and 7.0), the alkalinity will be preserved for turbidity

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precipitation, and the finished water will be neither corrosive or scaling.
According to Malaysia standards the maximum allowable limit for drinking water
is 15 TCU.
Comments: Based on the literature review both turbidity and pH don’t fall in the
range if Malaysia water drinking standards are ignored. This can be due to the
fact that optimum dosage, pH varies widely depending on the wastewater used.
One limitation of our experiment is that detailed analysis of wastewater
contents is not carried out, for which it makes it difficult to compare my results
with the literature.
5.3 Use of PACl as effective coagulant:
1) This literature has been taken form “I water wiki”. The commonly used
metal coagulants are aluminium and iron based. The aluminium coagulants
include: include aluminum sulfate, aluminum chloride and sodium aluminate.
The iron coagulants include ferric sulfate, ferrous sulfate, ferric chloride and
ferric chloride sulfate. Themain advantage of using these coagulants is because
of their ability to form multi-charged polynuclear complexes with enhanced
adsorption characteristics. There have been great improvements in
development of pre-hydrolyzed inorganic coagulants. These include aluminum
chlorohydrate, polyaluminum chloride, polyaluminum sulfate chloride,
polyaluminum silicate chloride and forms of polyaluminum chloride with
organic polymers. These polymers can work efficiently over a wide range of pH
and raw water temperatures. They are less sensitive to low water
temperatures; lower dosages are required to achieve water treatment goals;
less chemical residuals are produced; and lower chloride or sulfate residuals
are produced, resulting in lower final water TDS. They also produce lower
metal residuals.

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2) Based on another paper written by (Peter Gebbie, 2001) carries out a study
based on PACL coagulants for water treatment. Two main aluminum based
coagulants are widely used Alum and PACL. Alum (aluminum sulfate is
commonly used but has a number of disadvantages :
 limited coagulation pH range: 5.5 to 6.5,
 ¨ supplemental addition of alkalinity to the raw water is often required to
achieve the optimum coagulation pH, particularly for soft, coloured surface
waters that are common in Australia,
 ¨ residual aluminum levels in the treated water can often exceed
acceptable limits, and
 ¨ Alum floc produced is particularly fragile. This is especially important if a
coagulant is required to maximize color removal in a microfiltration-based
water treatment process.
Alum reacts in water to produce aluminum hydroxide and as a by-product
sulphuric acid is also formed. The metal hydroxide precipitates out of
solution and entraps neutralized charged dirt particles (turbidity), as well as
coagulating soluble color and organics by adsorption. The sulphuric acid
produced reacts with alkalinity in the raw water to produce carbon dioxide,
thus depressing the pH.
Polyaluminium coagulants have a general formula (Aln (OH) mCl (3n-m)) x
and have a polymeric structure, which is totally soluble in water.
Characteristics like polymerized chain, molecular weight and number of
ionic charges is determined by the degree of polymerization. However in on
application bases there is little difference between the performance of ACH
and PACl in water treatment applications, even though ACH is more
hydrated. Following are the advantages of Polyaluminium coagulants:
 Have higher basicity due to the ratio of hydroxyl to aluminum ions in the
hydrated complex

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 They are effective over a broader pH range compared to alum and they
work satisfactorily between range of 5.0-8.0
 Another important advantage of using polyaluminium coagulants in water
treatment processes is the reduced concentration of sulphate added to the
treated water.
 low levels of residual aluminum in the treated water can be achieved,
typically 0.01-0.05 mg/L,
 ¨ PACl and ACH work extremely well at low raw water temperatures. Flocs
formed from alum at low temperatures settle very slowly, whereas flocs
formed from polyaluminium coagulants tend to settle equally well at low
and at normal water temperatures,
 ¨ less sludge is produced compared to alum at an equivalent dose, lower
doses are required to give equivalent results to alum. For example, a dose
of 12 mg/L
 PACl (as 100%) was required for treatment of a coloured, low turbidity
water (Otway region, Victoria) compared to similar performance obtained
when using an alum dose of 55 mg/L, and
 ¨ the increase in chloride in the treated water is much lower than the
sulphate increase from alum, resulting in lower overall increases in the TDS
of the treated water.
Following are the examples illustrated from the paper which shows the
results of using PACL and alum as coagulants by different water treatment
companies
DAYLESFORD
Table 1: Raw water analysis, Wombat Reservoir at Daylesford
ION (mg/L) CaCO3
CALCIUM 1.8 4.5
MAGNESIUM 2.3 9.5

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A
jar test is carried out to determine the treatability of raw water supplies at this
company. Following are the results obtained:
Table 2: treated water quality Predicted Using WaterQual, Wombat Reservoir
COAGULANT LSI CCPP TDS SO4
(AS ION)
ALUM -2.2 -8.2 94 21.0
PACl -2.2 -7.9 67 1.5
TIDAL RIVER
The raw water supplied at Tidal River is derived from a small weir and off
take. The volume of the weir and areas relatively small and therefore substantial
changes to the raw water can occur during rainfall. Initially liquid alum and casting
soda were used in the treatment regime. The water was found difficult to be
treated and in an attempt to improve plant performance, PACL was used.
Table 3: Predicted performance of ALUM vs. PACl at Tidal River (at 15o
C)
COAGULANT DOSE
(mg/L)
ALKALI AND
DOSE (mg/L)
Pre Post
pH CCPP LSI $/ML
ALUM (as
100%)
50 NaOH
18.0
0 6.6 -28.7 -3.1 174
PACl as
(100%)
17.5 5.0 0 6.8 -21.1 -2.8 150
SODIUM 9.0 19.6
POTASSIUM 0.7 0.9
ALKALINITY 19.0 16.3
CHLORIDE 11.7 16.5
SULPHATE 1.5 1.6

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Both PACL and ACH provide significant advantage over alum including:
 Reduced chemical cost
 lower residual aluminum levels in the treated water,
 improved treated water quality including lower TDS and sulphate levels
and possibly higher CCPP values, and
 Lower sludge production.
Comments : As for the consideration of the use of coagulant is considered;
satisfactory results are obtained from the experiment which are shown in Table
5 – Table 8. If carefully observed that values obtained for Color, TSS, turbidity
and aluminum is all below the range for a standard drinking water which to a
large extent agrees with the literature and also the range of pH for which is used
varies roughly from 6.9-9.02 after PACl addition which agrees with ( Peter
Gabbie, 2001) where it is specified from 6.0-8.0 and for our experiment it only
crosses 8 in SET 2 for reasons mentioned above. However from our experiment
it cannot be stated that it is better than ALUM or any other coagulants because
comparison wasn’t made for which it can be a part for future works.

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6. EXPERIMENTAL PLANNING & DEVELOPMENT
A Gantt chart is used to display the activities for experimental planning carried
out during the spring semester. A Gantt chart is a type of bar chart, displaying
project activities as bars measured against a horizontal time scale.
Table 4: experiment schedule from the start till the end
1 Preparation stage Sat 17/1/15 Wed 4/3/15
1.1 Literature research Sat 17/1/15 Sat 24/1/15
1.2 Decide on objective
and parameters to test
on
Mon 26/1/15 Wed 28/1/15
1.3 Draft of experimental
procedure
Thu 29/1/15 Tue 3/2/15
1.4 Prepare Risk
Assessment
Mon 2/2/15 Fri 6/2/15
2 Get HIRACH approval Mon 9/2/15 Wed 4/3/15
2.1 Prepare experimental
proposal
Tue 10/2/15 Tue 17/2/15
2.2 Get proposal approved
by dr. Chong
Wed 18/2/15 Sun 1/3/15
2.3
Collect Water Sample Wed 25/2/15 Thu 26/2/15
2.4 Collect Chemicals and
apparatus
Mon 2/3/15 Wed 4/3/15
3 Experimental stage Wed 4/3/15 Thu 19/3/15
3.1 Carry out Experiment
Set 1
Wed 4/3/15 Fri 6/3/15
Set 2
Mon 9/3/15 Wed 11/3/15
Set 3
Thu 12/3/15 Mon 16/3/15
Set 4
Tue 17/3/15 Thu 19/3/15
4
Report Writing Stage Fri 3/4/15 Mon 20/4/15
4.1 Analyse Results Fri 3/4/15 Tue 7/4/15
4.2 Write on discussion Thu 9/4/15 Mon 13/4/15
4.3 Write on uncertainty
and error
Tue 14/4/15 Fri 17/4/15

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Based on the above activity schedule a Gantt chart was drawn which is shown
below.
Figure 2 : Gantt chart
4.4 Write on conclusion Thu 9/4/15 Wed 15/4/15
4.5 Compiling Report Thu 16/4/15 Fri 17/4/15
4.6 Report Submitted Mon 20/4/15 Mon 20/4/15

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7. METHODS
7.1 MATERIALS & APPRATUS REQUIRED:
 40 L of raw water
 1.5 L beakers
 Coagulant dosage
 pH value
 150 mL beakers
 Electronic weigh balance
 Spatula
 Glass rod
 200 mL volumetric flask
 250 mL volumetric flask
 Funnel
 Stopper
 Stop watch
 pH meter
 syringe
 HACH spectrophotometer
 Sample cells
 Double- manometer pump
 Conical flask
 Filter papers
 Flocculator
 Deionized water
 Ascorbic acid powder
 AluVer 3 (Aluminum reagent powder)
 Bleaching 3 reagent powder

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7.2 PREPARATION OF RAW WATER:
1. 40 L of raw water will be collected by the security guard from Sungai Sering Ulu
Kelang.
2. The raw water will be enclosed tightly in a large plastic container to prevent
leakage.
3. The raw water will be shaken and mix thoroughly before the experiment to
ensure a homogeneous mixture is obtained.
4. The raw water will be poured into a bucket before transferring into beakers to
reduce spillage due to the choking effect from the big plastic container.
5. Clean 1.5 L beakers labeled ‘control’ and 1 to 5 will be filled with 1 L of raw
water each.
7.3 Preparation of 1 M Ca (OH)2 Solution:
1. Gloves and goggles should be worn when preparing dilute Ca (OH) 2 solution
with water because the reaction is highly exothermic.
2. A clean and dry 100 mL beaker will be placed on an electronic weigh balance
and set the reading to zero.
3. Use a dry spatula to transfer 18.53 g of Ca (OH) 2 solid into the beaker.
4. Distilled water will be added into the beaker and stirred with a glass rod to fully
dissolve the Ca (OH)2 solid.
5. The solution will be left to cool down for 15 minutes as dissolving Ca (OH)2 in
water is exothermic.
6. The solution will be poured slowly into a 250 mL volumetric flask using a funnel
to avoid spillage.
7. Rinse the beaker and glass rod thoroughly with distilled water and pour the
rinsing water into the volumetric flask.

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8. Distilled water will be added into the volumetric flask carefully until the bottom
of the meniscus is level with the horizontal line on the neck of the flask.
9. The flask will be stoppered and by holding the stopper into the neck of the
flask, carefully turn the flask upside down multiple times to ensure thorough
mixing of the solution.
10. The volumetric flask will be labeled as ‘1M Ca (OH) 2 solution’.
7.4 Preparation of 0.15 M Polyaluminium Chloride:
1. A clean and dry 200 mL beaker will be prepared and placed on an electronic
weigh balance and set the reading to zero.
2. Use a dry spatula to transfer 6.54 g of Polyaluminium Chloride (PAC) powder
into the beaker.
3. Distilled water will be added into the beaker and stirred with a glass rod to fully
dissolve the PAC powder.
4. The solution will be poured slowly into a 250 mL volumetric flask using a funnel
to avoid spillage.
5. Rinse the beaker and glass rod thoroughly with distilled water and pour the
rinsing water into the volumetric flask.
6. Distilled water will be added into the volumetric flask carefully until the bottom
of the meniscus is level with the horizontal line on the neck of the flask.
7. The flask will be stoppered and by holding the stopper into the neck of the
flask, carefully turn the flask upside down multiple times to ensure thorough
mixing of the solution.
8. The volumetric flask will be labeled as ‘0.15 M PAC solution’.

23 | P a g e
7.5 Experimental Procedures
7.5.1 Set 1: Variation of PAC dosage
1. Place the samples prepared under the stirrers of Lovibond Flocculator.
2. Lower down the stirrer manually and make sure the stirring blade do not
contact with wall of the beaker.
3. Set the speed of stirring at 150 rpm and start stirring. Add the PAC stock
solution to beakers labeled 1 to 5 with dosage 0.1, 0.2, 0.3, 0.4 and 0.5mL
respectively. No PAC is added to the “control” beaker.
4. Start the stopwatch right after PAC is added to all beakers.
5. Use pH meter to measure the pH in each beakers and record the values.
6. Reduce the stirring speed of the stirring blade to 100rpm after 5 minutes.
7. Stop the stirrer after 15 minutes of stirring and allow the samples to settle for
15 minutes.
8. Use a syringe to collect about a 750mL supernatant from each beaker (the
beaker can be tilted and try to avoid getting solids into the needle).
9. Carry out experiment to test for its turbidity, color, total suspended solid and
aluminum content. Record all the readings.
10. Choose the sample with least turbidity and its corresponding coagulant
dosage as the optimal coagulant dosage.
11. Plot graph of coagulant dosage vs. color, turbidity, aluminum and TSS
7.5.2 Set 2: Variation of pH (optimum dosage of PAC)
1. Repeat the experiment of Set 1 from steps 1 to 9.
2. Increase the pH of the samples in beakers 1 to 5 to pH 7.36, 8.1, 8.5, 9.04 and
9.02 respectively by adding calcium hydroxide.

24 | P a g e
3. Instead of adding the PAC dosage differently in each beaker in step 4, add the
optimum dosage of PAC found in experiment Set 1 to beakers 1 to 5.
4. Measure and record the pH of the samples after adding PAC.
5. Based on the results of the parameters tested, choose the optimum pH for the
sample.
6. Plot graph of pH vs. color, turbidity, aluminum and TSS
7.5.3 Set 3: Variation of settling time
1. Repeat the experiment of Set 1 from steps 1 to 9.
2. Adjust the pH of the samples in beakers 1 to 5 to the optimum pH found in
Set 2.
3. Instead of adding the PAC dosage differently in each beaker in step 4, add the
optimum dosage of PAC found in experiment Set 1 to beakers 1 to 5.
4. Instead of allowing all the samples to settle for 15 minutes in step 7, change the
settling time of beakers 1 to 5 to 0.5, 1, 1.5, 2.0 and 2.5 hrs. respectively.
5. Record all the experimental results obtained.
6. Plot graph of settling time vs. color, turbidity, aluminum and TSS
7.5.4 Set 4: Variation of stirring speed
1. Adjust the pH for each beaker up to 7 before adding 0.1mL of PACl
2. Start the stop watch and set the desired stirring speed time for 35 min
3. Put the beakers one by one with varying speeds of 150, 200, 250, 300 RPM;
not all at once. 35 min for each desired speed.

25 | P a g e
4. Then let the particles in beaker settle down for 1.5 hrs after every 35 min of
mixing
5. Observe the behavior of solids in samples and records all the experimental
results obtained.
6. Plot graph of stirring speed vs. color, turbidity, Aluminum and TSS
7.6 TESTING METHODS:
Color
1. Stored program: 120
2. Preparing blank
-Prepare 100mL deionized water
-Pour the 50mL into filter paper
-Turn on vacuum and throw the deionized water away
-Pour the remaining deionized water into filter paper
-Turn on vacuum
-Blank is prepared (10mL)
3. Preparing sample
-Prepare 50mL of sample
-Pour into filter paper
-Sample is prepared (10mL)
4. Line of cell faces right
Aluminum
2. Fill the centrifuge tube (50mL) with sample
-Put ascorbic acid and invert it to dissolve the powder
-Add aluminum reagent powder and keep inverting it for 1 min
3. Preparing blank
-Pour 10mL into the cell
-Add bleaching powder

26 | P a g e
-Shake vigorously
-Leave it for 15 minutes
4. Preparing sample
-Pour 10mL into the cell
Turbidity
2. Prepare 1 blank of deionized water and 1 sample with 10mL each.
Total Suspended Solid (TSS)
2. Prepare 1 blank of deionized water and 1 sample with 10mL each
Figure 3: HACH spectrophotometer used for color and aluminum test

27 | P a g e
Figure 4: HACH Colorimeter used for TSS and turbidity test

28 | P a g e
8. RESULTS & DISCUSSION:
Table 5: Data obtained for a blank solution
TSS 24 mg/L
Turbidity 34 FAU
Color 190 PtCo
Al 0.017 mg/L
The values obtained for the blank as shown in table… are way above the required
values of standard drinking water which was expected as this water was not
treated.
SET 1:
Table 6: data obtained for set 1
PAC (ml) pH before adding PAC TSS (mg/L) Turbidity (FAU) Al (mg/L) Color(PtCo)
0.1 7 0 0 0.026 4
0.2 6.9 2 1 0.028 12
0.3 6.9 1 1 0.03 11
0.4 6.9 1 1 0.035 8
0.5 6.9 1 1 0.051 14
From graph 1 the trend observed for the aluminum is that the concentration is
increasing with increase in dosage. The coagulant added is an aluminum based
coagulant which leads to an increase in the aluminum content. It can also be
noted from the graph that TSS increases until it reaches a maximum point and
then starts decreasing gradually and then remains constant. The sudden rise of
TSS initially suggest that coagulant added is not enough to carry out the charge

29 | P a g e
neutralization process, due to which the coagulant added also becomes the part
of suspended solids. Further increase in coagulant dosage aids in the coagulation
process and brings the TSS down. 0.1 mL of PACl dosage which is equivalent to
2.6mg is selected as optimum dosage.
Graph 1: Effect of varying PACl dosage on TSS and Aluminum
Graph 2: Effect of varying PACl dosage on Color and Turbidity
0
0.01
0.02
0.03
0.04
0.05
0.06
0
0.5
1
1.5
2
2.5
0 0.2 0.4 0.6
Aluminium
(mg/L)
TotalSuspendedSolids
(mg/L)
PACl Dosage
(mL)
TSS
Aluminium
0
0.2
0.4
0.6
0.8
1
1.2
0
2
4
6
8
10
12
14
16
0 0.1 0.2 0.3 0.4 0.5 0.6
Turbidity
(FAU)
Colour
(PtCo)
PAC Dosage
(mL)
Colour
Turbidity

30 | P a g e
From Graph 2 the trend observed for color is unusual. It increases up to a
maximum point then decreases to a minimum point and shoots up again. The
color factor can be due to present of NOM (Natural organic material) that has not
settled since the color is caused by the dissolved species. On the other hand,
turbidity can be also another factor which increases the color of water which is in
turn caused by the particles in suspension, which may differ in size form colloidal
to aid dispersion and they reduce the clarity of water (Reynolds and Richards ,
1996) ( G.Seyrig and W.Shan , 2007 ). It is also observed that as PACl dosage
increases turbidity linearly increases then reaches a steady state value. One of
the trends observed from (A.F.Ashery, K.Radwan and M.L. Gar Al-Alm Rashed;
2010) is that the trend for tubudity decreases exponentially and becomes
constant with increase in alum dosage. The trend observed from our results
definitely does not match the one observed from the literature and this can be
due to the presence of suspended solids in the supernatant.
SET 2:
Table 7: Data obtained for set 2
PACl
(ml)
pH before adding
PAC l pH after adding PAC l TSS (mg/L) Turbidity (FAU) Al (mg/L) Color (PtCo)
0.1 7.36 7.18 0 0 0.02 0
0.1 8.1 7.91 1 1 0.026 2
0.1 8.5 8.27 1 1 0.044 9
0.1 9.04 8.85 1 1 0.018 3
0.1 9.44 9.02 1 1 0.036 5

31 | P a g e
Graph 3: Effect of varying pH on TSS and Al
Graph 4: Effect of varying pH on Turbidity and Color
From graph 3 it is observed that TSS linearly increases with pH and then reaches a
constant. For aluminum the graph shows a zig-zag trend which basically means it
doesn’t have any trend. A similar trend for turbidity is observed in graph 4 which
is similar to that of TSS in graph 3. Also a similar trend is observed for color in
graph 4 which is in turn similar to that of aluminum in graph3. The similarity
observed for TSS and turbidity is because measurement of turbidity is done by the
diffusion of scattered light which is caused by undissolved particles. This degree of
diffusion depends on: type of particles, size of particles, concentration (number of
particles), type and shape of particles, etc. (John Daly ,2007). The similar trend of
0
0.01
0.02
0.03
0.04
0.05
0
0.2
0.4
0.6
0.8
1
1.2
7 7.5 8 8.5 9 9.5 10
Aluminium
(mg/L)
(mg/L)
pH before adding PAC
TSS
Aluminium
0
0.2
0.4
0.6
0.8
1
1.2
0
1
2
3
4
5
6
7
8
9
10
7 7.5 8 8.5 9 9.5 10
Turbidity
(FAU)
Colour
(PtCo)
pH before adding PAC
Colour
Turbidity

32 | P a g e
TSS and turbidity pretty much says for itself that turbidity is affected by TSS and
TSS is in turn affected by pH which affects the coagulation process as stated in
literature review. Similarly color is also caused by dissolved organic matter e.g.
(humic and fulvic acids ). From this explanation it is quite obvious that zig zag
trend of aluminum affects the color change and also if observed the zig zag
pattern or trend shows that the value is different at every pH and is changing
which can be because with different pHs the color is different, is that the color-
producing substances in water behave inconsistently. pH adjustment may cause a
change in the ionization of the color molecule with corresponding effects on bond
lengths and configurations and thus light absorption (Gregoire Seyrig, Wenqian
Shan, 2007). Also if compared to the literature review the pH at which maximum
removal of turbidity occurs is usually between 6-6.5 and for our experiment the
pH variation itself starts from 7.0. But the drinking water standards in Malaysia
allow the pH level to be in a range of 6.5-9.0. So selecting pH 7.0 is the right
choice.
SET 3:
Table 8: Data obtained for set 3
PACl (ml) Settling Time (Hr) pH before adding PACl
pH after adding
PACl TSS (mg/L)
Turbidity
(mg/L)
0.1 0.5 7.12 6.87 2 2
0.1 1 7.22 7.09 2 1
0.1 1.5 7.12 7.02 0 0
0.1 2 7.12 7.09 2 4
0.1 2.5 7.1 7.09 1 2
Aluminum
(mg/L) Color (mg/L)
0.028 14
,0.021 9
0.028 5
0.026 4
0.025 2

33 | P a g e
Graph 5: Effect of settling time on TSS and Al
Graph 6: Effect of settling time on Color and turbidity
From graph 5 it is observed that with settling time both aluminum and TSS show a
similar trend. 1.5 hrs is selected as the optimum settling time for our experiment.
Aluminum content is maximum but TSS is minimum at that value. As shown in
table 1 that raw water already contains 0.017mg/L of aluminum in it. Adding PACl
just adds the amount of Al content already present to a higher value which then
gives a maximum value at 1.5 hrs. But as settling time is an increased aluminum
content decrease due to coagulation process leading to formation of flocks which
0
0.005
0.01
0.015
0.02
0.025
0.03
0
0.5
1
1.5
2
2.5
0 0.5 1 1.5 2 2.5 3
Aluminium
(mg/L)
(mg/L)
Settling Time
(Hours)
TSS
Aluminium
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0
2
4
6
8
10
12
14
16
0 0.5 1 1.5 2 2.5 3
Turbidity
(FAU)
Colour
(PtCo)
Settling Time
(Hours)
Colour
Turbidity

34 | P a g e
settles down with time. But now after 1.5 hrs both content of TSS and turbidity
(in graph 6) increases; whereas color decreases with time. Such inconsistency in
TSS and turbidity can be because the flocs might fall apart a period of time. The
mechanism of PAC coagulation is charge neutralization. Flocs from this are often
loosely packed and fragile (Lee et al., 2014).
SET 4:
Table 9: Data obtained from set 4
PACl
(ml) Settling Time (Hr) Stirring Speed pH before adding PACl pH after adding PACl TSS (mg/L)
0.1 1.5 150 7.36 7.15 0
0.1 1.5 200 7.33 7.1 1
0.1 1.5 250 7.31 7.08 0
0.1 1.5 300 7.3 7.15 1
Turbidity (FAU) Al (mg/L) Color (Pt/Co)
1 0.009 8
1 0.023 4
0 0.013 6
1 0.023 14

35 | P a g e
Graph 7: Effect of impeller speed on TSS and Al
Graph 8: effect of impeller speed on Color and Turbidity
From graph 7 it is observed that both aluminum and TSS follow the same trend
where TSS and aluminum content is maximum at RPM of 250 and it is minimum at
RPM of 250. A similar trend is followed by turbidity where it is minimum at 250
RPM but color shows a different trend than the rest of the graphs. The color
content increases with increase in RPM and it is minimum at 200 RPM. But there
is a similarity between all the 4 graphs which is that the slope for all the graphs
0
0.005
0.01
0.015
0.02
0.025
0
0.2
0.4
0.6
0.8
1
1.2
140 190 240 290 340
Aluminium
(mg/L)
(mg/L)
Impeller Speed
(RPM)
TSS
Aluminium
0
0.2
0.4
0.6
0.8
1
1.2
0
2
4
6
8
10
12
14
16
140 190 240 290 340
Turbidity
(FAU)
Colour
(PtCo)
Impeller Speed
(RPM)
Colour
Turbidity

36 | P a g e
increases after 250 RPM whereas for color it increases after 200 RPM. The rise in
the trend TSS and aluminum suggest that there was inappropriate mixing. Even
though there is only a slight variation of turbidity and TSS. These results varied
because of the fact that the device measured in only whole numbers. The trend of
the increasing slope after a certain speed for all the graph suggest that the
increased in impeller speeds have caused shearing stress (as stated in the
literature) on the molecule causing re-stabilization of colloids which remains in
suspension then. Another consideration which can be made is the presence of
turbulent eddies which would have dissipated a considerable amount of energy,
leading to break up of the flocs. As discussed in literature review that high
velocity gradients results in greater aggregation but as it is observed from graph 8
that after a impeller speed of let’s say 200 RPM the trend increases for color again
which tells us that speed below or above an optimal RPM would cause a decrease
in flocculation effectiveness due to the kinetic energy and potential energy of the
particles hitting so hard that they break up the floc. 250 RPM is selected as
optimal stirring speed for the process which comparatively than the other three
speeds has lower values for all the 4 dependent variables.

37 | P a g e
9. ERRORS AND UNCERTANITIES:
One of the important factors which were not considered was temperature. There
are some unusual trends observed in turbidity for which reasons are specified in
the discussion part but temperature plays an important role as well; which was
not considered in our experiment. Slight reduction in color removal was detected
at lower temperatures by some researchers; other researchers found that the
temperature had no impact on the reduction of color (Braul et al., 2001; Knocke
et al, 1986; Hansen and Cleasby 1990). But turbidity is sensitive to temperature
which also affects the particle counts during coagulation (Braul et al, 2001). This
might be the reason for the fluctuation in our results. Also its effect on the
kinetics of hydrolysis reaction, particle flocculation, and coagulant dosage is
ignored.
As it seen in graph 4 in Result and Discussion section both color and aluminum (in
graph 3) shows peaks and a trough at pH 8.5 and 9. This trend is explained in
discussion section but another error which might affect the results is the over
dosage of PACl in the process. No experiment was carried out with a dosage of
less than 2.6mg/L to know the changes. This argument can also be supported by
the fact that throughout the experiment for set 2, set 3 and set 4 pH values were
taken before and after addition of PACl (shown in Table 3, 4 and 5) with negligible
change observed which suggest that the pH didn’t affect coagulant process so it
might be because of over dosage that affected the results.
Values of turbidity, TSS, Al and color obtained might not be true because the
supernatant which was collected from the experiment for set 3 and 4 were not
immediately tested. The samples were left for 3-4 days uncovered without any
paraffin sheets or any other sort of cover. This might result in settling of particles
when it is not required or might be a change in chemical composition of
supernatant. Some uncertainties observed during the experiment like; the

38 | P a g e
formation of a visible scum on the surface of the water. This might have shoot up
the values for turbidity and TSS.
Also an error later in the experimental procedure is realized after the experiment
was done. That is set 4 should have been carried out before set 3 . As written in
experimental procedure in section 7 of the report that 35 min were allotted to
each stirring speed and then additional 1.5 hrs was then allotted for each stirring
speed. Due to which the flocks would eventually have settle, along with number
of suspended colloids (Greville, 1997). This also means that with sufficient settling
time, the removal efficiency by stirring speed is difficult to investigate.
Final source of error is the accumulation of human error and random error.
Parallax error might have been when taking supernatant by pipette; even the
pipette used is not accurate as well. Scratches in sample cell, inaccurate readings
of volume, and inappropriate mixing of solutions for testing are some of the
random errors which might have resulted in strange results.

39 | P a g e
10. Conclusion, recommendation and future works
To conclude the report the values observed for all the sets were mostly within the
specified range for drinking water which also means that turbidity, color,
aluminums and TSS were efficiently removed which was the main aim of the
experiment. If compared to the literature review for set 1 it didn’t follow the
trend for turbidity or color which is stated as in literature. For set 2 the pH values
varied and the optimal pH selected was again not within the range as specified in
the literature. For settling time and stirring speed as such literature data or values
were not discussed but the theory predicted in literature was somewhat
applicable to our situation.
To mitigate the errors and to undo the mistakes occurred following are the
recommendations and future work which should be taken into account:
 Temperature should be investigated in the experiment with proper
literature studied
 More than one coagulants should be used in the experiment to investigate
the effective of each individual for water treatment
 A range of stock solutions should be prepared and results should be carried
out accordingly to get proper trends and results
 Additional jar test with different natural raw water should be conducted to
verify the observation in this study.
 Water turbidity and settled coagulation flocs were tested and analyzed in
this study. Further study should be extended to suspended flocs to find a
direct relationship between water turbidity and suspended flocs
 Test for BOD (biological oxygen demand), DOC (dissolved organic carbon)
and other minerals should be carried out to further purify water.

40 | P a g e
11. REFERENCES
 Yi Geng (2005). Application of Flocs Analysis for Coagulation
Optimization at the split lake water treatment plant
at:http://www.collectionscanada.gc.ca/obj/s4/f2/dsk3/MW
U/TC-MWU-189.pdf. [Accessed 16 April 2015].
 Safaa.N.hassan (2011). The effect of settlement time on
reducing coagulant doasage in water treatment plants.
Avalilable at
http://www.jes.sohag.edu.eg/VOL.%20VII/4.pdf. [Accessed
20 April 2015]
 Emerson Process Management. (2009). Coagulation and
Flocculation. Available:
http://www.neilstoolbox.com/bibliography-
creator/reference-website.htm. [Accessed 15th April
2015.].
 Dr.Adil Al –Hemiri and Tahseen Hameed Al-Taey. (2008).
The Effect of Temperature and pH on the Removal /
Recovery of ZN++ from Solution by Chemical Coagulation.
Iraqi Journal of Chemical and Petroleum Engineering. 9 (-),
1-6.
HEM TRADE. (2014). Color Removal in Pulp and Paper
Effluent Using Inorganic Coagulants. Available:
http://www.generalchemical.com/assets/pdf/Color_Remov
al_in_Pulp_and_Paper_Effluent.pdf. [Accessed 19th April
2015.].
 KIM LUU (2000). STUDY OF COAGULATION AND SETTLING
PROCESSES FOR IMPLEMENTATION IN NEPAL.

41 | P a g e
MASSACHUSETTS at
http://web.mit.edu/watsan/Docs/Student%20Theses/Nepa
l/Luu2000.pdf. [Acessed 15 April 2015]
 S.D.Freese, K. Hodgson and D.J. Noziac (2004). FACTORS
AFFECTING COAGULATION WITH POLYELECTROLYTES: ARE
THESE QUANTIFIABLE. Cape Town. Document
Transformation Technologies at
http://www.ewisa.co.za/literature/files/031.pdf. [Accessed
18th
April 2015].
 J. R. Backhurst, J. H. Harker and J. F. Richardson. (2005).
Sedimentation. In: J. F. Richardson and J. H. Harker Coulson
and Richardson's Chemical Engineering Volume 2- Particle
Technology and Separation Processes (5th edition). 5th ed.
Oxford: Butterworth-Heinemann. 237-267.
 IWA WATER WIKI. (-). Coagulation and Flocculation in
Water and Wastewater Treatment. Available:
http://www.iwawaterwiki.org/xwiki/bin/view/Articles/Coag
ulationandFlocculationinWaterandWastewaterTreatment.
[Accessed 18th April 2015].
 D.J.Pernitsky (2003). COAGULATION 101.Calgary at
https://awwoa.ab.ca/pdfs/Coagulation%20101.pdf.
[Accessed 18th
April 2015].
 James M. Ebelinga, , , Philip L. Sibrellb, Sarah R. Ogdena,
Steven T. Summerfelta. (2003). Evaluation of chemical
coagulation–flocculation aids for the removal of suspended

42 | P a g e
solids and phosphorus from intensive recirculating
aquaculture effluent discharge. Aquacultural Engineering.
29 (1-2), 23-42.
 John Daly. (2007). What is Turbidity?. Available:
http://www.isanorcal.org/download/tech2007_presentatio
ns/turbidity.pdf. [Accessed 17th April 2015].
 Minisry of Health Malaysia. (-). Drinking Water Quality
Standard. Available: http://kmam.moh.gov.my/public-
user/drinking-water-quality-standard.html. [Accessed 20th
April 2015].
 U.S. EPA Science Advisory Board Consultation. (2003).
DEVELOPING WATER QUALITY CRITERIA FOR SUSPENDED
AND BEDDED SEDIMENTS (SABS). ,20.
 Peter Gebbie. (2001). USING POLYALUMINIUM
COAGULANTS IN WATER TREATMENT. 64th Annual Water
Industry Engineers and Operators’ Conference. 40-47.
 Ahamed Fadel Ashery, Kamal Radwan, and Mohamed I. Gar
Al-Alm Rashed. (2010). The effect of pH control on turbidity
and NOM removal in conventional water
treatment. Fifteenth International Water Technology
Conference, IWTC. 1-14.
 Anthony S. Greville.. (1997). How to Select a Chemical
Coagulant and Flocculant. Easy Treat Environmental. - (-), 1-
10.

43 | P a g e
 Grégoire Seyrig , Wenqian Shan. (2007). COAGULATION
AND FLOCCULATION: COLOR REMOVAL. 1-14.
 Chai SiahLee, JohnRobinson, MeiFongChong. (2014). A
reviewonapplicationofflocculantsin wastewatertreatment.
ProcessSafetyandEnvironmentalProtection. 1-20.
 Lenntech. (1998). EU's drinking water standards. Available:
http://www.lenntech.com/applications/drinking/standards
/eu-s-drinking-water-standards.htm. Last accessed 20th
April 2015.

44 | P a g e
12. APPENDIX:
Preparation of 1M Ca(OH)2 solution:
Molar weight of Ca(OH)2 = 74.1 g/mol
Concentration of Ca(OH)2 needed = 1 M
Volume of Ca(OH)2 solution needed = 250mL = 0.25 L
Number of mole of Ca(OH)2 = (0.25 L) x (1 mol/L) = 0.25 mol
Weight of Ca(OH)2 needed = (74.1 g/mol) x (0.25 mol) = 18.53 g
Preparation of 0.15M Polyaluminium Chloride:
Molar weight of PAC = 174.45 g/mol
Concentration of PAC needed = 0.15 M
Volume of PAC solution needed = 250ml = 0.25 L
Number of mole of PAC = (0.25 L) x (0.15 mol/L) = 0.0375 mol
Weight of PAC needed = (174.45 g/mol) x (0.0375 mol) = 6.54 g
Wt% of PAC solution = 6.54g / 250g = 2.6%

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