COAGULATION OF TURBID WATER
USING NATURAL MATERIAL: CACTUS
YEOH KAR CHUAN
1i1NEfiSfii MAIAYSiA SABAH
DISSERTATION SUBMITTED IN PARTIAL
FULFILMENT OF THE REQUIREMENT FOR THE
DEGREE OF BACHELOR OF SCIENCE WITH HONOURS
INDUSTRIAL CHEMISTRY PROGRAMME
SCHOOL OF SCIENCE AND TECHNOLOGY
UNIVERSITI MALAYSIA SABAH
APRIL, 2007
UNIVER. 3IT1 MALAYSIA SABAfi
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-ATATAN: ' Potong yang tidak bakcnaan. "" lika tcsis ini SUUT atau TERHAD, sila Iampirkan vim dariptada pihak berkwn/organisasa
' I+erkenaan dcngan menyaakan sekali sebab dan tempoh tesis ini perlu dikdaskan scbagai SUUT dan TF. RNAD.
© Tesis dimaksudkan sebagai tesis bagi Ijayah Doktor Falsa. 'ah dan Sarjana sot: an penyelidikan, atau disertasi bagi pcngajian tac=ra kcrja kvrsus dan Ixsyelidikan, atau Laporan Projck Sarjana Muds (LPSM).
(Mcngandungi makiumat yang berdujah kescLinatan atau SULIT kepwtingan Malaysia scpecti yang tamaktub di dalam
AKTA RAHSIA RASMi 1972)
TERHAD (Vicngandungi maklumat TERHAD yang tclah ditentukan oleh organisasi/bsdan di nuaa peayclidikan dijalankan)
TIDAK TERIf^D
I
DECLARATION
I hereby declare that this dissertation is based on my original work, except for quotations
and summaries each of which have been fully acknowledged.
ellý
ý YEOH KAR CHUAN
APRIL 2007
HS2004-2395
VERIFICATION
NAME: YEOH KAR CHUAN
TITLE: COAGULATION OF TURBID WATER USING NATURAL MATERIAL: CACTUS
r,
I Y_ý
(PROF. MADYA DR. MARCUS JOPONY)
()o (DR. MD. LUTFOR RAHMAN)
574'007
(PFOF MADYA DR SHARIFF A. K. OMANG)
APRIL, 2007
ACKNOWLEDGEMENT
I would like to express my gratitude especially to my project supervisor, Prof. Madya Dr.
Marcus Jopony for his guidance, supervisions, advises and patiences along the period of
this research. 1 am grateful to Mr Sani for his kindness and willingness to lend a helping
hand especially towards the lab equipment to make my project a successful one.
I am very thankful for the support given by my family. To all my fellow friends
who are there to help and willing to share information and ideas in the joint effort to
complete the dissertation, thank you all so much!
ABSTRACT
The ability of cactus (Opunnu frcus indica) as natural coagulant for treatment of turbid
water was tested according to jar test. Kaolin was used to produce the synthetic turbid
water. The experiment variables were coagulant dosage, initial turbidity value and pH. For comparison, a similar study was carried out using a conventional coagulant,
aluminium sulphate. Coagulation using cactus attained a maximum of turbidity removal
efficiency of 74.9% for initial turbidity of 60.5 NTU compared to 73.1% by alum. The
optimum dosage for cactus and alum was 0.03g and 0.2g respectively. As the cactus dosage increased, turbidity removal efficiency dropped until 58.2% compared to alum
which remained constant at about 72.2°/ö. As the initial turbidity increased, turbidity
removal efficiency for cactus decreased but increased for alum. The optimum initial
turbidity for both cactus and alum was 41 NTU and 81.5 NTU, respectively. Effect of pH
varies for both alum and cactus. The optimum pH for cactus was 2 at 0.015g and 0.03g
dosage while for alum is 6 at 0.2g dosage. As the pH increased, turbidity removal
efficiency for cactus decreased but remained uncertain for alum.
PROSES PENGGUMPALAN PADA AIR NERUN DF'11 GA, 1' MF'. N000'; 1: 4AAN BA IIAN SEMULAJADI: KAKTUS
A BSTRA k
Keupuvuun kuktu. c (Opuntia /icuc tndre"u) untuk hertinduk . cehugur . culuh . cutu huhun
pengguntpul . cemululadr Jtu/t dengan menggunukun 'Iur test' untuk ruwutun air keruh.
Kaolin ditamhah sehugat kekeruhan. Proses penggumpulun kuktuc drku/t dengan
menggunakun Jar tester : Antara juktor yang dikaji termusuk umuun huhun penggumpal, kekeruhan awal dun pH. Alum digunakan . cehugui contoh huhun pe ngguntpul yang hiu. cu digunakan untuk tujuan perhundingan. Proses pengt, ºumpulun kaktuc mencupur sehanvuk
, 4.9% keherkesunun penvtngkrran kekeruhan hag, kekeruhun uwul 60.5 N7'l / Jr mama iu humptr
. cerupu dengan alum . cehunvak 73.1 % bagi mengu. /i jaktor umuun penggumpal.
Hunvu (1.03g kaktuc digunakan jika dthandrng dengun 0.2g alum di munu tu uduluh
amaun yang optimum bagi penggumpal "Id. cmg-ma. cing. Apuhilu amaun hahan
penggumpul hertamhah, keherke. canun penvrngkiran kekeruhan menurun . cehinggu 58.2%
manukula hagi alum, ia kekal sebanvak 72.2%. Apuhila kekeruhan awal hertumhuh,
keherke. cunun penvrngkrran kekeruhan herkurang bagi kuktuc tetupr hertumhah hug, ulu'M
Kekeruhan uwa/ optimum bagi kakluc ta/ah a/ N77 / manukalu hagi alum la/uh 81.5 NT( I.
pH optimum hugi kuktuc ia/ah 2 hagi amaun huhun penggumpul . cehanvak 0-015g Jan
0.03g manakala pH optimum bagi alum ialah 6 bagi amaun huhun penggumpal . cehunvak
0.2g. ApahNa pH herlamhuh, keherke. canun penvmgkirun kekeruhun menurun bagi kuktuc
tetupi tidak tentu hagi alum.
vi l
CONTENTS
TITLE OF THESIS
DECLARATION
VERIFICATION
ACKNOWLEDGEMENT
ABSTRACT
ABSTRAK
CONTENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF PHOTOS
LIST OF APPENDIX
LIST OF SYMBOL & ABBREVIATIONS
CHAPTER 1 INTRODUCTION
1.1 Overview
1.2 Cactus
1.3 Objectives of study 1.4 Scope of study
CHAPTER 2 LITERATURE REVIEW
2.1 Water Turbidity
2.2 Sedimentation Process
2.3 Chemistry of Coagulation Process
2.3.1 General Mechanism
2.3.2 Double Layer Compression Mechanism
2.3.3 Enmeshment Mechanism
2.3.4 Adsorption and Charge Neutralization Mehcanism
2.3.5 Adsorption and Interparticle Bridging
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XI
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2.4 Type of Coagulants
2.4.1 Inorganic Coagulants
2.4.2 Synthetic Organic Polymer Coagulants
2.4.3 Natural Occurring Coagulants
2.5 Characteristic of Coagulation Process
2.5.1 Jar Test
2.5.2 Effect of Dosage
2.5.3 Effect of pH 2.5.4 Effect of alkalinity 2.5.5 Effect of temperature
CHAPTER 3 METHODOLOGY
3.1 Turbid Water Samples
3.1.1 Kaolin Suspension
3.1.2 River Water Samples
3.2 Natural Coagulant-Sample and Its Preparation
3.3 Coagulation Experiments
3.3.1 Effect of Coagulant Dose
3.3.2 Effect of Initial Turbidities
3.3.3 Effect of pH
3.4 Measurement of Turbidity
CHAPTER 4 RESULTS AND DISCUSSION
4.1 Effect of Coagulant Dosage
4.2 Effect of Initial Turbidity
4.3 Effect of pH
CHAPTERS CONCLUSION AND FUTURE WORKS
5.1 Conclusions
5.2 Future Works
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RF: FF: RF: 1('FS
APPENDIX
x
LIST OF TABLES
Page
Table 3.1 Summary of the experiment design to test the effect of coagulant dose 29
Table 3.2 Summary of the experiment design to test the effect of initial turbidities 30
Table 3.3 Summary of the experiment design to test the effect of pH 32
XI
LIST OF FIGURES
Figure 2.1 Electrochemical properties of a colloidal particle Figure 2.2 Different dosages to treat synthetic water with different initial turbidity Figure 2.3 Effect of pH on removal of turbidity in Periyar River water Figure 2.4 The effect of alkalinity on the final turbidity using doses of
Prosopisjuliflora
Figure 2.5 Different coagulant dosages to treat synthetic water in different
temperature
Figure 4.1 Effect of altering the dosage of cactus (initial turbidity=60.5 NTU) Figure 4.2 Turbidity removal efficiency at different cactus dosage
(Initial Turbidity=60.5NTU)
Figure 4.3 Effect of altering the dosage of alum (Initial turbidity=85 NTU)
Figure 4.4 Turbidity removal efficiency at different alum dosage
(Initial Turbidity-- 85 NTU)
Figure 4.5 Effect of altering the initial turbidity using cactus coagulant Figure 4.6 Turbidity removal efficiency of cactus at different initial turbidity Figure 4.7 Effect of altering the initial turbidities using alum coagulant
Figure 4.8 Turbidity removal efficiency of cactus at different initial turbidity
Figure 4.9 Effect of altering the pH using 0.015g and 0.030g cactus
(Initial turbidity=59NTU)
Figure 4.10 Turbidity removal efficiency of cactus at different pH
Figure 4.11 Effect of altering the pH using 0.2g alum (Initial turbidity=85NTU)
Figure 4.12 Turbidity removal efficiency of alum at different pH
Page
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J(ii
LIST OF PHOTOS
Photo 3.1 Kaolin suspension Photo 3.2 Water sample Photo3.3 Opuntra jicus indica
Photo 3.4 Dried Grinded Cactus
Photo 3.5 Jar tester apparatus (Phipps and Birds Model 300)
Photo 3.6 pH meter Photo 3.7 Turbidity meter
Page
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LIST OF APPENDIX
Appendix A The raw data of coagulation using cactus and alum
Appendix B Calculation methodology for turbidity removal efficiency Appendix C Calculation methodology for preparing acid
Appendix D Calculation methodology for preparing alkali
Appendix E List of contaminants in its different level, potential health effects
and the source of the contaminants.
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XIV
LIST OF SYMBOL AND ABBREVIATIONS
NTU
FTU
JTU
rpm
g
mg
m
mm
AM L
mg/1
mV °C
N
q
Nephelometric Turbidity Unit
Jackson Turbidity Unit
Formazin Turbidity Unit
Round per minute Gram
Milligram
Metre
Milimetre
Micrometer
Litre
Zeta potential Concentration in milligram per litre
milivolt Degree celcius Electrophoretic velocity, cm/s
Viscosity of the medium
E Dielectric constant on the medium
x applied potential per unit length of cell
CHAPTER I
INTRODUCTION
1.1 Overview
The presence of suspensions solids pollutant can cause the raw water to have h gh
turbidity. In order to achieve such water standard, water treatment plants carry out a series
of processes. The process specifically is to remove suspended solids or to reduce the
water turbidity which is also known as sedimentation (Bryant et al., 1992). According to
WHO guidelines and standard, treated water for human consumption should have a
turbidity value that is less than 5NTU (WHO, 1984).
Typically, coagulant is used to speed up the sedimentation. The effect of a
coagulant depends on several factors. These factors include type of coagulant, dosage of
coagulant (Diaz et al., 1999), pH (Droste, 1997) and initial turbidity (Zhang et al., 2005).
Conventionally, inorganic coagulants such as aluminium sulfate, aluminium chloride and
ferric chloride are used. Under certain conditions, synthetic organic polymer coagulants
are used.
2
Due to health and economic reasons, there is a growing interest for the use of
natural coagulants. Examples of natural coagulants are starch, starch derivatives, proteins,
algae, chitosan, tannins, strychnos polatorum, moringa olifeira and tamarindis indica
seeds (Droste, 1997). Natural coagulants are preferred in some aspects because of its
abundance source, low price, innocuity, multifunction and biodegradation (Zhang et al.,
2006).
1.2 Cactus
This plant belongs to the Cactaceae family. Cactus is normally found in North America,
South America and West Indies and it is able to adapt to the extreme and environment
and display a wide range of anatomical and physiological features which conserve water.
Cactus can be a source of food in the form of pear-shaped berries which can be process
into jam and jellies (Anderson, 2001). The species of cactus that is used for this research
is known as opuntia ficus indica or cactus latifaria (Diaz et al., 1999). Previous studies by
Zhang et al., 2005 stated that the potential of cactus as a coagulant is due to its contents in
terms of nutrition and medicinal components such as proteins, amylase, malic acid, resin,
vitamins and cellulose. It is shown that cactus has the similar properties of Moringa
oleifera (Zhang et al., 2005).
3
1.3 Objectives of study
The objectives of this study are:
a) To determine the effect of dosage of coagulant towards cactus coagulation of
turbid water
b) To determine the effect of initial turbidity towards cactus coagulation
c) To determine the effect of pH towards cactus coagulation
d) To compare cactus with conventional coagulant namely alum
1.4 Scope of study
The main focus of the research is the potential of the natural coagulants namely cactus to
function like any other conventional coagulants such as alum and iron derivatives that are
available. In this study, jar test experiments will be carried out to investigate the
coagulant ability of cactus under varying dosage, initial turbidity and pH conditions. The
test water to be used is kaolinite suspension.
('HAPTER 2
LITERATURE REVIEW
2.1 Water Turbidity
Impurities in water often cause the water to appear turbid or be coloured. Impurities
include suspended and colloidal materials and soluble substances (Culp et al., 1986).
Turbidity is a result of the scattering and absorption of light by suspended solids (Droste,
1997).
Turbidity is determined by the optical property that causes light to be scattered,
adsorbed or reflected rather than transmitted in a straight line through or into a liquid. In
the nephelometric method, the intensity of scattered light in a sample is compared with
the intensity of light scattered by a standard reference solution under the same condition.
The higher the intensity of scattered light, the higher the turbidity. Light dispersing units
are used for low turbidity water such as potable water and light scattering units are used
for water containing more turbidity (Alley , 2000). According to the Rayleigh's law, it is
observed that size and concentration of particles are able to influence the measurement of
the turbidity (Droste, 1997).
5
The units in measuring the turbidity include Nephelometric Turbidity Unit (NTU),
Jackson Turbidity Unit (JTU) and Formazin Turbidity Unit (FTU). A turbidity meter is
used to measure the turbidity. Turbidity level which is above 1.0 NTU is associated with
significant increases in total coliform densities (Droste, 1997). According to the Surface
Water Treatment Rule (SWTR), the maximum allowable treated drinking water turbidity
is established at 5.0 NTU (Bryant et al., 1992).
2.2 Sedimentation Process
Sedimentation is used to remove settleable solids from liquids (Alley, 2000). It is a
process that involves exposing the water to relatively quiescent conditions that will allow
the removal of solids from water by gravity settling (Droste, 1997). The rate of
sedimentation can be determined by using Stokes'law (Eckenfelder, 2000).
2
Vs= 18
(P, -Pz) N
where,
v, = rate of sedimentation in cm/s
g=acceleration due to gravity
d= particle diameter in cm
p, =density of the particle in g/cm3
p2=density of the fluid in g/cm3
p=viscosity of fluid in poises
(2.1)
6
According to the equation, the rate of sedimentation, v, will increase with the
increase of the particle or aggregate size, d. The rate of sedimentation can be enhanced
using coagulants. Coagulants will gather the suspended particles to form a bigger
aggregate to ease the process of sedimentation.
2.3 Chemistry of Coagulation Process
Coagulation is defined as an irreversible combination or aggregation of semi solid
particles, such as fats or proteins, to form a clot or mass (Sax &Lewis, 1987). In another
word, coagulation is a process of gathering the suspended matter in untreated water for
the purpose of settling and prepared the water for filtration process.
Coagulation process is employed for the removal of waste materials in suspended
or colloidal form. Conventional physical treatment process cannot remove these particles
as it does not settle out on standing due to its size range of I nm to 0. I nm (E: ckenfelder,
2000). In this finely dispersed condition, the colloidal particles are able to remain stable
because the particles are so small that the Brownian movements, caused by the collision
of the water molecules with the colloids, dominate over the influence of the gravity.
Besides that, the electric repulsive forces results from the surface charge of colloids are
able to prevent the coagulation of the particles (Henze et al., 1995).
7
By adding the coagulant, the particles will aggregate which results the
destabilization of the colloids. This happens in 2 separate and distinct phases. First, in
order for the particles to be destabilized, repulsion force between the particles must be
overcome. This is follow by the contact between the destabilized particles that must be
induced to ensure that the aggregation can occur. The destabilization step can be achieves
further by blending in rapid mix tanks (Culp et al., 1986).
Colloids present in the wastewater consist of 2 types which is the hydrophobic and
hydrophilic. Hydrophilic colloids such as proteins have a strong tendency to bind or
absorb water with the functional groups such as the amino group (-Ntl2), hydroxyl group
(-OH) and also organic acid group (-COON) serves as the hydrophilic property of the
organic colloids. The binding or absorption of water occurs through the production of so
called hydrogen bindings. It will cause the hydrophilic particles remain enclosed by a
water jacket which follows the particles in their movements. The water jacket is termed as
bound water (Henze et at., 1995). The absorbed water will retard the flocculation and
normally requires special treatment to achieve effective coagulation (Eckenfelder, 2000).
The hydrophobic colloids such as clays have no affinity at all for the liquid medium and
also lack the stability in the presence of electrolytes. It is readily susceptible to
coagulation (Eckenfelder, 2000). The hydrophobic particles do not have the water jacket.
8
2.3.1 General Mechanism
The theory to explain the coagulation process of colloidal systems is based on the
presence of physical factors such as electrical double layers that surrounds the colloidal
particles in the solution and counterion adsorption. A reduction in the electric potential
(zeta potential) between the fixed layer of counterions and the bulk of the liquid is
required in the destabilization (Culp et al., 1986).
Colloids with its electrical properties are able to prevents agglomeration and
settling by create a repelling force. Stabilizing ions are strongly absorbed to an inner fixed
layer that provides a particle charge that varies with the valence and number of adsorbed
ions (Eckenfelder, 2000). The charges on the colloids must be counterbalanced by ions of
opposite charge in the solution that are arranged in an electrical double layer in order for
electroneutrality to exist. The effective thickness of the double layer is influenced greatly
by the ionic concentration and slightly affected by the size of the colloid. The electrical
potential created by the surface charges will attract counterions toward the colloidal
particles. The center of the closest counterions is separated from the surface charge by a
layer of thickness which represents the Stem layer. The electrical potential drops linerarly
along this layer. Beyond the Stern layer, the electrical potential decreases exponentially
with distance from the particle in the diffuse layer (Culp et al., 1986). Figure 2.1 shows
the electrochemical properties of a colloidal particle (Eckenfelder, 2000).
9
compact layer diffuse layer
0) 0
-7v .r ý ý
a
EH
G
6
Outer Helmholtz Plane Inner Helmholtz Plane
-am. X
Figure 2.1 Electrochemical properties of a colloidal particle
Although the magnitude of the charge on the colloid can't be measured directly,
the value of the potential at some distance from the colloid can be computed (Culp et al.,
1886). The zeta potential, ý is defined as the potential drop between the slipping plane and
the body of solution and is related to the particle charge and thickness of the double layer
where else the thickness of the double layer is also inversely proportional to the
concentration and valence of nonspecific electrolytes (Eckenfelder, 2000). Normally, the
electrophoretic mobility of the colloidal particles is used by observing the particle
mobility through the microscope in order to compute the zeta potential (Culp et al., 1986).
The following equation is the common form of zeta potential equation, where zeta
potential, ý can be obtained:
46
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