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

BORACIYG PENGESAiIAN STATUS TFSIS@

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(Hi1RUF BESAR) mcngak-u mcmbenarkan tcsis (LPS/Sujaru/Dok(oc Fakafah)" ini disimpaa di Perpustakun Uaivctsiti Malaysia Sabah datglsn syarat-syarat kegunaan scpcrti batkut:

I. Tests adalab baktnitik Univcniti Malaysia Sabah. 2.1Scrpustaksan Universiti Malaysia Sabah dibeaartian membuat saliaan uatuk tujuan pestSajiaa sabaja. 3. Pcrpustakaaa dibcnarkan membuat saliasn tcsis ini scbagai bahan pcrtukatan antan iastitusi peagajian

tinggi. o rf, 'ýi: ý'i dhAN

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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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X111

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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

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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

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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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