UNIVERSITI TUN HUSSEIN ONN MALAYSIA
STATUS CONFIRMATION FOR MASTER’S THESIS ELECTROKINETIC-ASSISTED PHYTOREMEDIATION OF HEAVY METAL
IN RIVERBANK SOIL
ACADEMIC SESSION : 2015/2016 I, SUHAILLY BINTI JAMARI, agree to allow this Master’s Thesis to be kept at the Library under the following terms: 1. This Master’s Thesis is the property of the Universiti Tun Hussein Onn Malaysia. 2. The library has the right to make copies for educational purpose only. 3. The library is allowed to make copies of this report for educational exchange between higher
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Approved by,
(WRITER’S SIGNATURE) (SUPERVISOR’S SIGNATURE) ASSOC. PROF. DR.ZAIDI BIN EMBONG
Permanent Address: D16, KAMPUNG PARIT RAJA AHMAD,
83500 PARIT SULONG, BATU PAHAT,
JOHOR DARUL TAKZIM.
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ELECTROKINETIC-ASSISTED PHYTOREMEDIATION OF HEAVY METAL IN
RIVERBANK SOIL
SUHAILLY BINTI JAMARI
A thesis submitted in
fulfillment of the requirement for the award of the Degree of
Master of Science
Faculty of Science, Technology and Human Development
Universiti Tun Hussein Onn Malaysia
JUNE 2016
ii
I hereby declare that the work in this thesis is my own except for quotations and
summaries which have been duly acknowledged
Student : ...........................................................
SUHAILLY BINTI JAMARI
Date : ...........................................................
Supervisor : ...........................................................
ASSOC. PROF. DR. ZAIDI BIN EMBONG
iii
For my beloved family
Muhammad Syazwan bin Shariffudin Sasidharan
Muhammad Zhariff Zhakwan bin Muhammad Syazwan
Muhammad Zhariff Zhafran bin Muhammad Syazwan
Saodah binti Sapuan
Shariffudin Sasidharan bin Abdullah
Rohana binti Haron
And all my family members
iv
ACKNOWLEDGEMENT
Bismillahirrahmanirrahim
The whole journey of this study was conducted to prove that EK technique does
contribute to the improvement of phytoremediation method. In 2012, the study was
started by selecting the suitable sampling site and collecting soil samples at the Sedi
River with the endless support of my supervisor; Associate Professor Dr. Zaidi bin
Embong, and fieldwork assistant; Mr. Mohd. Hanafi bin Mokhtar. Despite of his
disability, Associate Professor Dr. Zaidi bin Embong tirelessly taught and guided me on
how the study should be done.
The whole year of 2013 was spent on conducting the EK assisted phytoremedition
study and in year 2014, the treated soil and plant samples were completely analyzed. The
challenges in sample analysis process were to meticulously prepare the samples prior to
analysis which sometimes took almost ten times of repetitions. The limited number of
analyses equipments versus high number of students using it was also delaying the lab
work. There was one time where the sample analysis process was delayed for almost two
months due to equipment malfunction. Year 2015 was spent on analyzing the data and
results obtained from the sample analysis processes. After all blood, sweat and tears, the
findings of this study were compiled in this thesis. Therefore, I would like to express my
earnest gratitude to my supervisor, Assoc. Prof. Dr. Zaidi bin Embong for his way of
guidance, supervision and support throughout my research. My appreciation also goes to
Mr. Mohd. Hanafi bin Mokhtar for assisting me in fieldwork tasks. I would also like to
extend my appreciation to:
- Physics Laboratory 3 (FSTPi) staff; Mr. Asrul and Mr. Iskandar
- RECESS staff; Mdm Salina Sani, Mr. Amir Zaki and Mr. Mudzaffar Syah
v
- Environmental Analysis Laboratory (FKAAS) staff; Mdm Nadiah, Mdm
Fazliana and Mr. Redzuan
- Materials Science Laboratory (FKMP) staff; Mr. Tarmizi and Mr. Anuar
- RECESS postgraduates members
My family occupies a special place in this acknowledgement. I find no words to
express my appreciation to my dearest husband and sons; Muhammad Syazwan bin
Shariffudin Sasidharan, Muhammad Zhariff Zhakwan bin Muhammad Syazwan and
Muhammad Zhariff Zhafran bin Muhammad Syazwan for their love, patience and
everlasting support, together with my mother, my parents in laws and all my family
members.
Not to forget, I would like to express my gratitude to the government as this work
was funded by the Ministry of Higher Education of Malaysia under the Exploratory
Research Grant Scheme Vot. E008 entitled “Electrokinetic-assisted Phytoremediation of
Heavy Metal in Riverbank Soil”.
To finish, I thank Allah for His grace, mercy and love that I could be at this point
of my life. I am aware that although I have been far from Him for so many times, but He
has always been with me. Thank you Allah.
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ABSTRACT
Electrokinetic (EK)-assisted phytoremediation is one of the environmental remediation
methods that have a big potential in enhancing the ability of plant heavy metal uptake in
soils. This study was conducted to investigate the difference in heavy metal composition
concentration of riverbank soil and the change of soil pH between pre and post
phytoremediation and EK assisted phytoremediation treatment. The selected
phytoremediation plant is Dieffenbachia ‘Tropic Rain”. The phytoremediation plant
treatment was fertilized with organic and chemical fertilizer while the EK
phytoremediation plant was induced with EK system (a pair of EK electrodes connected
to a direct current (DC) power supply with a magnitude of 6 V/cm-1 electric field) for 4
hours/day. The soil and plant samples from pre and post treatments were analyzed using
and X-ray Fluorescence Spectrometer (XRF), Scanning Electron Microscope / Energy
Dispersive X-ray Spectroscopy (SEM/EDX) and Inductively Coupled Plasma Mass
Spectrometer (ICP-MS). After 12 months of EK assisted phytoremediation treatment, the
soil pH near the cathode increase 48.8% from pH 4.32 to pH 6.43 while in anode region
the pH decrease 28% from pH 4.32 to pH 3.11. The element concentrations in cathode
region for most elements of interest (Ni, Cu, Zn, As and Pb) were higher than anode and
middle region with the highest is (47.3 ± 0.6) ppm Pb. The elemental concentration of Ni,
Cu, Zn, As and Pb by EK assisted phytoremediation plants were slightly higher than the
elements absorbed by the phytoremediation treated plants alone in the “chemical” and
“organic” slots with the highest is (7.98 ± 0.68) ppb Zn. This showed that the EK assisted
remediation treatment has increased the plant’s absorption during the phytoremediation
process.
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ABSTRAK
Pemulihan fito berelektrokinetik (pemuliharaan fito EK) adalah salah satu langkah
pemulihan alam sekitar yang mempunyai potensi yang besar untuk meningkatkan
keupayaan penyerapan logam berat oleh pokok dalam proses pemuliharaan tanah. Kajian
ini dijalankan untuk mengkaji kepekatan komposisi logam berat di dalam tanah tebing
sungai dan perubahan dalam pH tanah menggunakan teknik pemuliharaan fito dan teknik
pemulihan fito EK. Pokok yang dipilih untuk kajian ini adalah Dieffenbachia ‘Tropic
Rain”. Untuk teknik pemulihan fito, pokok dibajai dengan baja organik dan kimia
manakala teknik pemulihan fito EK dibekalkan dengan sistem EK yang mengandungi
sepasang elektrod yang disambung kepada punca kuasa arus terus (DC) dengan medan
elektrik sebanyak 6 V/cm-1 selama 4 jam sehari. Sampel tanah dan pokok dianalisa
menggunakan Spektrometer Pendafluor Sinar-X (XRF), Mikroskop Imbasan Elektron /
Spektrometer Sinar-X Sebaran Tenaga (SEM/EDX) dan Spektrometer Jisim Terganding
Plasma Beraruh (ICP-MS). Selepas 12 bulan rawatan pemulihan fito EK, pH tanah
kawasan katod meningkat 48.8% daripada pH 4.32 ke pH 6.43. pH tanah di kawasan
anod menurun 28% daripada pH 4.32 ke pH 3.11. Kepekatan unsur Ni, Cu, Zn, As dan
Pb di katod lebih tinggi berbanding anod dan kawasan tengah dengan kepekatan tertinggi
ialah (47.3 ± 0.6) ppm Pb. Kepekatan unsur Ni, Cu, Zn, As dan Pb yang terserap di dalam
pokok yang di rawat dengan teknik pemulihan fito EK didapati lebih tinggi daripada
unsur di pokok dengan rawatan teknik pemulihan fito sahaja (di dalam slot “kimia” dan
“organik”) dengan nilai paling tinggi adalah (7.98 ± 0.68) ppb Zn. Hal ini menunjukkan
bahawa teknik pemulihan fito EK berjaya membantu penyerapan unsur oleh pokok
semasa proses pemulihan fito.
viii
CONTENTS
TITLE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT vi
ABSTRAK vii
CONTENTS viii
LIST OF TABLES xii
LIST OF FIGURES xiv
LIST OF SYMBOLS AND ABREVIATIONS xviii
LIST OF EQUATIONS xx
LIST OF APPENDIXES xxi
CHAPTER 1 INTRODUCTION 1
1.1 Background of the Study 1
1.2 Problems Statement 3
1.3 Aim and Objectives of the Study 4
1.4 Scope of Study 5
1.5 Significance of Study 6
1.6 Structure of Thesis 6
CHAPTER 2 LITERATURE REVIEW 8
2.1 Introduction 8
2.2 The Issues of River Contamination Worldwide 9
2.3 The Issues of River Contamination in Malaysia 17
2.4 Remediation Techniques on Heavy Metals-Contaminated Soil
And Sediment 19
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2.4.1 Amendment 20
2.4.2 Sandcap 21
2.4.3 Washing 22
2.5 Phytoremediation 23
2.5.1 Techniques of phytoremediation 24
2.5.2 Mechanism of ion movement from soil to root 26
2.5.3 Ion absorption by plants 27
2.5.4 Hyperaccumulator 29
2.5.5 Phytoremediation plant candidate 31
2.6 Electrokinetics remediation 34
2.6.1 Electrokinetics transport processes 34
2.6.2 Physico-chemical processes in electrokinetics
remediation 36
2.7 Electrokinetic-Assisted Phytoremediation 39
2.8 Summary of Chapter 45
CHAPTER 3 METHODOLOGY OF RESEARCH 47
3.1 Introduction 47
3.2 Sampling Site Determination 48
3.2.1 Three potential sites 48
3.2.1.1 Sedi River, Yong Peng 49
3.2.1.2 Sembrong River, Kampung Sawah Sagil 50
3.2.1.3 Batu Pahat River, Batu Pahat 50
3.2.2 The equipments for sampling site determination 51
3.2.2.1 Ludlum Model 19 MicroR survey meter 52
3.2.2.2 Soil pH and Moisture Tester (DM-15) Takemura
Japan Test 53
3.2.3 Soil sample assessment and site determination 53
3.3 Soil Sample Collection 55
3.4 Phytoremediation Plant Candidate 57
3.5 Phytoremediation Reactor 57
3.6 Electrokinetics (EK) Set-up 60
x
3.6.1 The equipment for electrokinetic (EK) set-up 61
3.6.1.1 DC power supply (GW Instek
model GPR-11H30D) 62
3.7 Phytoremediation Observation 62
3.8 Sample Preparation 63
3.8.1 Sample for soil pH analysis 63
3.8.2 Sample for soil elemental composition analysis 63
3.8.3 Sample for plant elemental composition analysis 67
3.8.4 The equipments for sample preparation 71
3.8.4.1 Fritsch Planetary Mono Mill Pulverisette 6 71
3.8.4.2 Breitlander Laboratory Press PE-MAN 72
3.8.4.3 Favorit Stirring Hotplate HS0707V2 74
3.9 Sample Analysis 74
3.9.1 Soil pH analysis 75
3.9.2 Soil elemental composition analysis 75
3.9.2.1 XRF analysis for soil sample 76
3.9.2.2 SEM/EDX analysis for soil sample 77
3.9.3 Plant elemental composition analysis 78
3.9.3.1 SEM/EDX analysis for plant sample 78
3.9.3.2 ICP-MS analysis for plant sample 79
3.9.4 The equipments for sample analysis 80
3.9.4.1 Lutron Pen pH Meter Model PH-222 80
3.9.4.2 Bruker AXS S4 Pioneer 81
3.9.4.3 EDX spectrometer model JEOL JSM-6380-LA 82
3.9.4.4 ICP-MS (Perkin-Elmer Sciex model ELAN
9000) 83
3.10 Data Analysis 84
3.11 Summary of Chapter 84
CHAPTER 4 RESULTS AND ANALYSIS 86
4.1 Introduction 86
4.2 The changes of riverbank soil pH 87
xi
4.2.1 Comparison of soil pH between pre and post
phytoremediation and post EK assisted phytoremediation
treatments 88
4.3 Heavy metals mobility in riverbank soil 91
4.3.1 XRF analysis for soil samplesof pre and post
phytoremediation and post EK assisted
phytoremediaton treatment 91
4.3.2 SEM/EDX analysis for soil samples of pre and post
phytoremediation and post EK assisted
phytoremediaton treatment 98
4.3.3 Comparison between XRF and SEM/EDX
analyses on riverbank soil samples 104
4.4 The absorption of heavy metals by phytoremediation plants 110
4.4.1 SEM/EDX analysis for plant powder samples of pre and
post phytoremediation and post EK assisted
phytoremediaton treatment 110
4.4.2 ICP-MS analysis for plant samples of pre and post
phytoremediation and post EK assisted
phytoremediaton treatment 116
4.4.3 Comparison between SEM/EDX and ICP-MS
analyses on phytoremediation plant samples 121
4.5 Summary of Chapter 126
CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 127
5.1 Conclusions 127
5.2 Recommendations 128
REFERENCES 130
VITA 139
APPENDIX 140
xii
LIST OF TABLES
Table 1.1: Summary of some different remediation process 4
Table 2.1: Anthropogenic sources of several heavy metals in the environment 9
Table 2.2: Harmful effects of several heavy metals on human health 15
Table 2.3: Summary of the different techniques of phytoremediation process 25
Table 2.4: Several hyperaccumulator plant species and their metal-
accumulating capacities 30
Table 2.5: Summary of laboratory studies of EK assisted phytoremediation 45
Table 3.1: Site coordinates, soil and river water pH and environmental radiation
dose-rate readings 54
Table 3.2: Elemental composition data of the three sites using XRF analysis 55
Table 4.1: Soil pH for pre and post phytoremediation and post EK assisted
phytoremediation treatment 88
Table 4.2: Soil elemental concentration of Ni, Cu, Zn, As and Pb for pre
and post phytoremediation and post EK assisted phytoremediation
treatment by XRF analysis 92
Table 4.3: Soil elemental concentration of Ni, Cu, Zn, As and Pb for pre and
post phytoremediation and post EK assisted phytoremediation treatment
by SEM/EDX analysis 99
Table 4.4: Plant elemental concentration of Ni, Cu, Zn, As and Pb for pre
and post phytoremediation and post EK assisted phytoremediation
treatment by SEM/EDX analysis 111
Table 4.5: Plant elemental concentration of Ni, Cu, Zn and Pb for pre
and post phytoremediation and post EK assisted phytoremediation
xiii
treatment by ICP-MS analysis 117
xiv
LIST OF FIGURES
Figure 1.1: Heavy metal contamination in river system 2
Figure 1.2: The transport mechanism of heavy metal in the environment 3
Figure 2.1: Typical macroinvertebrates in different substrata 12
Figure 2.2: Heavy metals accumulation route 14
Figure 2.3: One of Minamata disease effect 17
Figure 2.4: The sample collection of Pahang River water for potential bauxite
mining pollution 18
Figure 2.5: The work of sand cap remediation technique 21
Figure 2.6: Typical process diagram of soil washing remediation technique 22
Figure 2.7: Techniques of phytoremediation process 24
Figure 2.8: Cross section of a plant root. Site of passive uptake is the apparent
free space which is outside the Casparian strip in the cortex 27
Figure 2.9: Diagram of a plant cell. Active uptake occurs at the plasmalemma 28
Figure 2.10: The plants use in the phytoremediation techniques : Dumb cane
(Dieffenbachia ‘Tropic Rain’) 32
Figure 2.11: Application of EK in the contaminated soil 35
Figure 2.12: EK assisted phytoremediation system 39
Figure 2.13: Schematic diagram of the electrodic phytoremediation system 40
Figure 2.14: A photo of ryegrass plant 41
Figure 2.15: A photo of (a) rapeseed (Brassica napus), and (b) tobacco
(Nicotiana tabacum) 42
Figure 2.16: The schematic diagram of the pot experiment 43
xv
Figure 2.17: The schematic diagram of lead removal from contaminated soil by
electrokinetic-assisted phytoremediation system 44
Figure 3.1: Three location of sampling sites; (i) Sedi River, (ii) Sembrong River,
(iii) Batu Pahat River 49
Figure 3.2: Google Streetview image of Sedi River from Jalan Besar, Yong Peng 49
Figure 3.3: Soil sampling work at Sembrong River, Kampung Sawah Sagil 50
Figure 3.4: Soil sampling work at Batu Pahat River, Batu Pahat 51
Figure 3.5: The portable Ludlum Model 19 MicroR Meter (left) and Soil pH
and Moisture Tester (DM-15) Takemura Japan Test (right) 52
Figure 3.6: The background radiation dose-rate measurement 52
Figure 3.7: The soil pH measurement using pH meter 53
Figure 3.8: The sampling site at Sedi River 55
Figure 3.9: Soil sample collection at the riverbank 56
Figure 3.10: The collected riverbank soil samples using clay pots 56
Figure 3.11: The phytoremediation reactor 57
Figure 3.12: A schematic design of phytoremediation reactor : (a) side view
of the reactor and (b) top view of the reactor. 58
Figure 3.13: The sequence order of the slot on the phytoremediation reactor 59
Figure 3.14: Two types of fertilizers used in this study; a) chemical (inorganic)
fertilizer, and b) organic fertilizer 60
Figure 3.15: The EK set-up 61
Figure 3.16: The DC power supply (GW Instek model GPR-11H30D) 62
Figure 3.17: The oven (model Memmert) 64
Figure 3.18: (a) The collected soil sample from cell, (b) The oven dried soil sample 64
Figure 3.19: The Fritsch Planetary Mono Mill Pulverisette 6 65
Figure 3.20: The ground soil sample in the grinding bowl 65
Figure 3.21: Endecotts Lab Test Sieve 50 µm 66
Figure 3.22: The Breitlander Laboratory Press PE-MAN and die sets 67
Figure 3.23: The pellets of soil samples for XRF analysis 67
Figure 3.24: The decontaminated plant samples; a) organic plant sample,
b) EK assisted phytoremediation plant sample, and c) chemical
xvi
plant sample 68
Figure 3.25: The samples heated on hot plate for nitric-perchloric acid digestion 70
Figure 3.26: Whatman Filter Paper No. 5 71
Figure 3.27: The working principle of the grinder 72
Figure 3.28: The Breitlander Laboratory Press PE-MAN 73
Figure 3.29: Die sets for Breitlander Laboratory Press PE-MAN 73
Figure 3.30: Favorit Stirring Hotplate HS0707V2 74
Figure 3.31: The pH measurement using Lutron Pen pH Meter Model PH-222 75
Figure 3.32: The XRF spectrometer (Bruker AXS S4 Pioneer) 76
Figure 3.33: a) Carbon conductive tape, b) The sample on stub for SEM/EDX
analysis 77
Figure 3.34: Typical EDX spectrum of soil sample 78
Figure 3.35: The ICP-MS (Perkin-Elmer Sciex model ELAN 9000) spectrometer 79
Figure 3.36: Lutron Pen pH Meter Model PH-222 80
Figure 3.37: Bruker AXS S4 Pioneer 81
Figure 3.38: EDX spectrometer model JEOL JSM-6380-LA 82
Figure 3.39: The ICP-MS schematic 83
Figure 4.1: The trend of soil pH for pre and post phytoremediation and post EK
assisted phytoremediation treatment 90
Figure 4.2: Soil elemental concentration of; (a) Ni, (b) Cu, (c) Zn, (d) As and
(e) Pb for pre and post phytoremediation and post EK assisted
phytoremediation treatment by XRF Analysis 94
Figure 4.3: Soil elemental concentration of; (a) Ni, (b) Cu, (c) Zn, (d) As and
(e) Pb for pre and post phytoremediation and post EK assisted
phytoremediation treatment by SEM/EDX Analysis 101
Figure 4.4: Comparison between elemental concentrations of; (a) Ni, (b) Cu, (c) Zn,
(d) As and (e) Pb by XRF and SEM/EDX analyses on riverbank soil
samples 105
Figure 4.5: Plant elemental concentration of; (a) Ni, (b) Cu, (c) Zn, (d) As and
(e) Pb for pre and post phytoremediation and post EK assisted
phytoremediation treatment by SEM/EDX Analysis 112
xvii
Figure 4.6: Plant elemental concentration of; (a) Ni, (b) Cu, (c) Zn, (d) Pb for
pre and post phytoremediation and post EK assisted
phytoremediation treatment by ICP-MS Analysis 119
Figure 4.7: Comparison between elemental concentrations of; (a) Ni, (b) Cu,
(c) Zn and (d) Pb by SEM/EDX and ICP-MS analyses on
phytoremediation plant samples 122
xviii
LIST OF SYMBOLS AND ABREVIATIONS
EK electrokinetics
XRF X-ray Fluorescence
SEM/EDX Scanning Electron Microscopy / Energy Dispersive X-ray
ICP-MS Inductively Coupled Plasma Mass Spectrometer
Ni Nickel
Cu Copper
Zn Zinc
As Arsenic
Pb Plumbum/lead
Z Atomic number
EDTA ethylenediamine tetracetic acid
EGTA ethylene glycol-bis-[2-aminoethylether]-N,N,N,N, tetracetic acid
EDDS SS-ethylene diaminedisuccinic acid
C carbon
H hydrogen
O oxygen
RECESS, UTHM Research Centre for Soft Soil, Universiti Tun Hussein Onn Malaysia
FKAAS, UTHM Faculty of Civil and Environmental Engineering, Universiti Tun
Hussein Onn Malaysia
HNO3 nitric acid
H2SO4 sulphuric acid
HClO4 perchloric acid
H2O2 hydrogen peroxide
xix
Si Silicon
Hg Mercury
Se Selenium
ppm parts per million
ppb parts per billion
xx
LIST OF EQUATIONS
NO. EQUATION PAGE
2.1 2H2O ↔ 4H+ + O2 + 4e- 36
2.2 4H2O + 4e- ↔ 4OH- + 2H2 36
3.1 T-test =
−−
1nSµχ
84
3.2 χ =
Σ
nx
84
3.3 S2 = ∑ −
−)( 2
11 χxn or S2 = ∑ − )( 21 χxn 84
xxi
LIST OF APPENDIXES
APPENDIX TITLE PAGE
A X-ray Micro-Analysis of Trace Elements (Ni, Cu, Zn)
Composition in Riverbank Soil by Electrokinetic-
Assisted Phytoremediation 140
B Elemental Composition Study of Heavy Metal (Ni, Cu, Zn) in
Riverbank Soil by Electrokinetic-Assisted Phytoremediation using
XRF and SEM/EDX 146
C XRF And EDX Analysis of Trace Element In River Bank Soil
By The Effect of Electrokinetic-Assisted Phytoremediation 153
D DC power supply (GW Instek model GPR-11H30D) 159
E Fritsch Planetary Mono Mill Pulverisette 6 182
F Breitlander Laboratory Press PE-MAN 190
G Lutron Pen pH Meter Model PH-222 192
H ICP-MS (Perkin-Elmer Sciex model ELAN 9000) 194
CHAPTER 1
INTRODUCTION
1.1 Background of the Study
Nowadays, heavy metals originating from anthropogenic activities are frequently detected in
sediments and water columns of river/lake, which cause a considerable number of the world’s
rivers/lakes severely contaminated. There are two classifications of heavy metal which are
essential and non-essential to the biological systems of living organism. Essential heavy
metals are necessary biological function of living organism while non-essential heavy metals
have no importance in living organisms (Ali, Khan &Sajad, 2013).
Anthropogenic activities are including mining, smelting, electroplating, agriculture
and etc. The contaminationcaused by the industrial and agricultural activities has been
emphasized in studies around the world due to the adverse biological effects on the health of
the aquatic environment. The effects are including aquatic life mortality and
immobilization.Figure 1.1 shows the heavy metal contamination in the river due to
anthropogenic activities. The fishes are dead due to high concentration of heavy metals in the
river water. Clearly, with this condition of river, it could be concluded that it is not safe for
human consumption.
The buildup of potentially toxic metals carries a huge risk to the beneficial uses and
sustainability of the natural resources such as water, plants and aquatic animals (Duan et
al.,2009; Ezemonye, Ogeleka, &Okieimen, 2009; Sultan &Shazili, 2010) and furthermore
could risk the life of human being. The migration of particle-reactive heavy metals from
riverbank sediment into bottom sediment through water diffusion may quickly adsorb onto
2
suspended matter and ultimately move to bottom sediment. In aquatic environment, heavy
metal is usually distributed as follows: water-soluble species, colloids, suspended forms and
sedimentary phases. However, heavy metals could not be removed by natural processes of
decomposition like organic pollutants does (Penget al., 2008).
Figure 1.1: Heavy metal contamination in river system(Glennie& Cox, 2014)
As heavy metals usually possess significant toxicity to aquatic organisms and affect
human health through food chain, therefore, riverbank soil /riverbank sediment remediation
need to be considered as the priority in order to reduce or prevent the heavy metal migration
into the river stream system.To clean up the heavy metal contamination in riverbank sediment
system, various techniques of remediation are able to be applied on the sites depending on the
condition and severity of the contamination level.
Some of the techniques are sand cap remediation technique, electrochemical
technique, excavation and bioremediation technique, just to name a few. However, an
extensive eco-technological technique such as phytoremediation can be a potential
remediation options for the existing areas of land disposed dredged sediments and for the
future treatment of the large volumes of contaminated dredged sediments. Figure 1.2 shows
the transport mechanism of heavy metal in the environment.
3
Figure 1.2: The transport mechanism of heavy metal in the environment(Sagasiki
Environmental Developments Co.,Ltd, 2002 )
1.2 Problems Statement
Contamination of inorganic metal in river, estuarine and marine sediment by anthropogenic
activities are frequently detected and risking the aquatic life. This irresponsibility act could
also threaten the life of human being. Besides mortality, heavy metal contamination could let
human being end up with various health problems such as dysfunctional of physical abilities,
mental problem and permanent handicap.Salem, Eweida, and Farag (2000) found the
relationship between high heavy metals concentration in drinking water and health problem in
human being in their study in Great Cairo Cities. The consumed heavy metals contaminated
drinking water lead to renal failure, hair loss, liver cirrhosis, and chronic anemia.
Realized with the seriousness of these issues, researchers all over the world has
conducted experiments and studies on how to restore or remediate the contaminated site to its
original condition, or at least to reduce the dreadful condition to a better state. The types of
remediation techniques were implemented depends on many factors such as the suitability of
the technique with the contaminated site, the types of heavy metal to be remediate, the cost
4
needed to conduct the study and many more. Table 1.1 summarized some of the common
remediation technique for heavy metal contamination.
Table 1.1: Summary of somedifferent remediation process(Peng, et al., 2008)
Phytoremediation is a developing innovative technique which uses living green plants
for reduction and/or removal of contaminants from contaminated soil, water, sediments, and
air. The main advantage of phytoremediation is it is low expense and can be used for in situ
application in large scales. As the plant could not rapidly absorb the increased soluble heavy
metals in riverbank sediment solution in a short time, another remediation technique needs to
be combined with this technique to improve the heavy metal absorption by the plant (Ali et
al., 2013; Anjum et al., 2013; Raskin& Ensley, 2000).
Therefore, a suitable remediation technique needs to be developed to control the risk
of heavy metals leaching into river stream system, as well as to decrease the heavy metal
mobility in sediment and uptake by marine life. This could be achieved by applying a new
remediation technique which uses a combination of phyto- and electrokinetic (EK) -
remediation, known as “EK AssistedPhytoremediation”. This new remediation technique will
also provide an alternative eco-technological technique to prevent the heavy metal in
riverbank soil from leaching into the river stream which can accumulate in sediment.
1.3 Aim and Objectivesof the Study
Remediation process Description
Amendments Decrease metal mobility and bioavailability by precipitation or sorption
Washing Heavy metals are shifted from the dredged sediment to washing solution such as acid washing, chelating agents or surfactant
Sand cap
Capping the contaminated sediment with sandy material, such as clean sediment, sand or gravel to decrease the direct contact between water and the contaminated sediment
Electrochemical remediation
Application of low DC current to electrodes which inserted to sediment and decontaminates the area
Phytoremediation The use of plant to detoxify contaminants
5
This study was conducted with the aim to reduce the heavy metal contamination in the river
system through EK-assisted phytoremediation technique. By applying this technique to the
riverbank of river, the problem of heavy metal leaching into the river systems could be control
thus reducing the mobility of heavy metal in sediment and uptake by marine life. There are
several things to be monitored during the study which are the change of soil pH and the
concentration of heavy metal in soil and plant for pre and post treatment. Thus, the following
objectives are to be achieved in order to fulfill the aim of the study;
a) To investigate and analyze the changes on the riverbank soil pH influencedbyEK
assisted phytoremediation treatment.
b) To study and analyze the improvement of heavy metal mobility in the riverbank soil
with the assistance of EK technique.
c) To compareand critically analyze the increase of heavy metal absorption in
Dieffenbachia ‘Tropic Rain’ between EK assisted phytoremediation treatment and
ordinaryphytoremediation treatment.
1.4 Scope of Study
This study was conducted as a response to the increase of heavy metal contamination in the
environment not only in Malaysia but up to worldwide level. It focuses on the physico-
chemical changes in the ex-situ phytoremediation of the riverbank soil with the aim to reduce
the heavy metal leaching into the river system and decreasing the heavy metal mobility in
sediment. Initially, three soil samples from three potential sampling sites in the area of Batu
Pahat rivers were collected. They are Sedi River, Yong Peng, Batu Pahat River, Batu Pahat
and Sembrong River, Kampung Sawah Sagilin which they have a close proximity to industrial
factories, residential area and agricultural activities.
Assessment of heavy metal concentration by X-Ray Fluoresence (XRF) analysis were
conducted on those samples. The selected sampling site, which is Sedi River, Yong Peng, was
determined from the assessment by which sample has the highest concentration of heavy
metal among all. The phytoremediation technique was conducted on the collected Sedi River
soil samples and assisted by EK techniques in order to improve the heavy metal absorption
capability by the phytoremediation plant; Dieffenbachia ‘Tropic Rain’ in the contaminated
6
riverbank soil environments. Dieffenbachia ‘Tropic Rain’ is selected as the phytoremediation
plant because they are abundant and grows well with no signs of deterioration in the sampling
area.
The study was conducted for 12 months duration. In this study, the soil and plant
composition were examined using various types of chemical analytical methods such as X-
Ray Fluoresence (XRF), Scanning Electron Microscopy/Energy Dispersive X-ray
spectroscopy (SEM/EDX) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). It
is expected that this studycan lead to the establishment of noble eco-technology remediation
technique which provides a “phytoremediation barrier” along the riverbank that capablein
reducing the heavy metal mobility into the river stream.
1.5 Significance of Study
River contamination is currently one of the major issues that need to be solved promptly. As
there are various types of remediation techniques for contaminated soil and river, the results
or findings of this study could give a better understanding on the concept of EK assisted
phytoremediation treatment. The implementation of EK assisted phytoremediation treatment
using tropical plant; Dieffenbachia ‘Tropic Rain’ could fulfill the aim to reduce the heavy
metal concentration in riverbank contaminated soil and establish a new retarding mechanism
of heavy metal ion mobility from the riverbank soil to the river stream. By reducing the heavy
metal leaching into the river system, the water quality of the river is able to be improved and
safer for human consumption. It is not only beneficial to human, but also to other living
organism and aquatic life.
1.6 Structure of Thesis
There are a total offive chapters consisted in this thesis including this introductory chapter.
They are introduction, literature review, methodology of research, results and analysis and
conclusions and recommendations chapters. The summary of each chapters are described as
follow:
a) Chapter 1: Introduction
7
This chapter gives details on the background of the study, problem statements,
research aims and objectives, scope of the study and the contribution of this
study.Some highlighted issuesof heavy metal contamination in environment are also
included in this chapter.
b) Chapter 2: Literature Review
This chapterpinpointed the international and national issues of heavy metal
contamination in the environment, especially the river contamination issues. The
history of remediation methods implemented to overcome the problem of
environmental contamination is also reviewed. Lastly, the focus of the review is on
EK-assisted phytoremediation technique which is conducted in this study and listed
the relevant history of EK-assisted phytoremediation experiments to the study.
c) Chapter 3: Methodology of Research
The chapter described how the study was conducted. The process of determining
Sedi River as the sampling site, the sample collection process andthe construction of
phytoremediation reactor was explained in detail. Moving further into the chapter,
the discussion was about thesoil and plant sample preparation which include the
process of turning the soil sample into powder and pellet form and preserving plant
sample by acid digestion method. The sample analysis process whichwereperformed
in this study using XRF spectrometer, SEM/EDX spectrometer and ICP-MS
spectrometer. The descriptions of all equipments utilized in this study were also
discussed.
d) Chapter 4: Results and Analysis
This chapter focuseson the obtained results from the phytoremediation and EK
assisted phytoremediation treatments based on the soil pH as well as soil and plant
elemental concentrations data analysis and discussing the early conclusions from the
findings.The soils were analyzed by means of XRF and SEM/EDX and plant
samples were analyzed using SEM/EDX and ICP-MS.
e) Chapter 5: Conclusions
This chapter provides conclusions of the study and determining whether the results
that were obtained in Chapter 4 achieving the three objectives of the study.
8
Limitations and recommendations of future work are also described as to improve
the future study.
CHAPTER 2
LITERATURE REVIEW
2.1 Introduction
The need for implementing a meticulous literature review is very crucial in any research. In
this chapter, the focal points of the discussion in the early sections are concerning the
enhancement of environmental contamination issues from year to year. This chapter is
critically discusesthis serious issue which does not only occur in Malaysia but up to
worldwide level.The source of the contamination; heavy metals, are discussed in the sections
and pinpoint the route of heavy metals pathway to the environment. The heavy metals
contamination issue does not only affected the environment, but also threatening human life.
Thus, the effects of heavy metals contamination to the water column of river, aquatic life and
most importantly human are also discussed in the chapter.
The chapter discussesfurther on the remediation methods employed by the authorities
and environmental professionals to overcome the crisis. There are various remediation
techniques to be employed depending on the condition of the contamination, location site of
the contamination, types of contaminants involved and the suitability of the method to the
solve the particular contamination issue. In this chapter, it illustrated and discussed some
remediation methods, including the one that was selected for this research; electrokinetic
(EK)-assisted phytoremediation method which have more advantages than the other method
9
and more suitable to be applied in this study. The explanation of the selected method is
discussed further in the last sections.
2.2 The Issues of River Contamination Worldwide
Heavy metalsmigrateinto the ecosystem from natural and anthropogenic sources(Ali, et al.,
2013). Anthropogenic sources of heavy metal from agriculture, mining, smelting,
electroplating, and other industrial activities have resulted in the accumulation of detrimental
concentration of metal such as As, Cd, Cr, Cu, Ni, Pb and Zn in soil (Raskin & Ensley, 2000).
Heavy metals are classified as essential and non-essential in terms of their role in biological
systems. Essential heavy metals such as Fe, Mn, Cu, Zn and Ni are necessary and needed for
vital physiological and biological function of living organismwhile non-essential heavy
metals such as Cd, Pb, As, Hg and Cr are not needed by living organisms (Ali, et al., 2013).
Table 2.1 listed the anthropogenic sources of several heavy metals in the environment.
Table 2.1: Anthropogenic sources of several heavy metals in the environment(Ali, et al.,
2013)
Heavy metal Sources As Pesticides and wood preservatives
Cd Paints and pigments, plastic stabilizers, electroplating, incineration of cadmium-containing plastics, phosphate fertilizers
Cr Tanneries, steel industries, fly ash Cu Pesticides, fertilizers
Hg Release from Au–Ag mining and coal combustion, medical waste
Ni Industrial effluents, kitchen appliances, surgical instruments, steel alloys, automobile batteries
Pb Aerial emission from combustion of leaded petrol, battery manufacture, herbicides and insecticides
The migration of particle-reactive heavy metals from the riverbank sediment into the
bottom sediment through water diffusion may quickly adsorb onto the suspended matter and
ultimately move to the bottom sediment. In aquatic environment, heavy metal is usually
spread out as follows: water-soluble species, colloids, suspended forms and sedimentary
10
phases(Peng, et al., 2008). Heavy metals may chemically or physically interact with the
natural compound, which changes their forms of existence in the environment. In general,
they may react with particular species, change oxidation states and precipitate (Dube, et al.,
2000). Heavy metals may be bound or absorbed by particular natural substances, which may
increase or decrease their mobility.
The transport mechanism of heavy metals through soil has long presented great
interest to both environmental and soil scientists because of the possibility of groundwater
contamination through metal leaching. In general many soils contain a wide range of heavy
metals with varying concentration ranges depending on the surrounding geological
environment and anthropogenic and natural activities occurring or once occurred. Therefore,
in this research, there are five elements of interest to be studied which is Ni, Cu, Zn, As and
Pb. These metals are commonly present in soil essentially or non-essentially and explain
further as follow:
a) Copper, Cu is a transition metal in rosy-pink color with an atomic number of 29 and
an atomic weight of 63.54. Pure Cu is ductile with a melting point of 1083oC. Cu
majorly presents in the divalent oxidation state (Cu2+) in aqueous solution while some
exist as univalent compounds and complexes of Cu in nature (Wright & Welbourn,
2002). Its sorption reactions are pH dependence. pH stands for potential of hydrogen
(H+). It represents the negative log of the hydrogen ion (H+) concentration on the scale
from 0 to 14, with 7.0 indicates that the medium is in neutral state, less than 7.0 is
classified as “acidic” and greater than 7.0 is “ alkaline” (Jones, 2012). Cuis typically
dissolved well in acidic to neutral medium rather than in alkaline state. Thus, Cu is
fairly soluble in water(Wright & Welbourn, 2002). Anthropogenic activities such as
agricultural and waste disposal activity have deposited pesticides, fertilizer and
sewage sludge which mobilize Cu into the environment and contaminating soils and
water bodies (Khan, Ahmad, & Rahman, 2007).The mobility of Cu in soils is also pH-
dependence where it associates with the soil properties; Cu is highly mobile in acid
medium, fairly mobile in oxidising conditions and a very limited mobility in alkaline
conditions (Wright & Welbourn, 2002).
b) Zinc, Znis a relatively malleable, bluish-white chemical element with an atomic
number of 30. It has an atomic weight of 65.39,a melting point of 419.6oC, a boiling
11
point of 907oC anda density of 7.133 g cm-3(Anjum, et al., 2013).Zn is commonly
found in divalent oxidation state (Zn2+) and is composed of five stable isotopes. In
certain soils, Zn encompasses a high concentration level while in natural water, it
forms a fairly weak complex (hydrated Zn2+ at pH between 4 and 7)(Wright &
Welbourn, 2002).
c) Nickel, Ni is a soft, silvery-white metal with an atomic number of 28. Due to its high
ductility, fair strength and hardness and good thermal conductivity, Ni is easily
fabricated with steel–making procedure. Ni is a transition metal under group VIIIa. Its
prevalent valence states are 0 and +2 but majorly found as Ni2+ species. Pristine
streams, rivers and lakes contain a range of 0.2 – 10 mg L-1 total dissolved Ni, surface
water near Ni mines and smelters contain up to 6.4 mg L-1 while seawater contains
approximately 1.5 mg L-1(Wright & Welbourn, 2002). Interventions of Ni in
environment;particularly in water bodies are frequently due to industrial effluent; ghee
and oil, surgical instrument, steel alloys and automobile batteries industries (Tariq,
Ali, & Shah, 2006)
d) Arsenic, As is a chemical element with an atomic number 33, an atomic mass of 74.92
and a specific density of 5.73(Wright & Welbourn, 2002). As present in various
minerals, typically hand in hand with sulfur and other metals and also in a form of a
pure elemental crystal. Chemicals and glasses manufacturing and smelting process of
Cu, Zn and Pb had liberated As into the environment. The manufacturing of As-
contained pesticides releases As in a form of arsine gas. As in water bodies lead to
contamination of shellfish, cod and haddock(Anjum, et al., 2013). Other sources of As
in environment are paints, rat poisoning, fungicides and wood
preservatives(Thangavel & Subbhuraam, 2004).
e) Lead, Pb is a bright luster, bluish-white metal with an atomic number of 82 and an
atomic weight of 207. Pb is commonly used in metal product manufacturing due to its
high melting point (327.5oC) and its resistance towards corrosion. Pb exists naturally
in trace amount at an average of 20 ppm in Earth’s crust. It mobilized by the process
of weathering and volcanic emission and ultimately mobile by anthropogenic activities
(Wright & Welbourn, 2002). The typical state of Pb is inorganic compound state of
Pb(II). It can also being found as Pb(IV) which formed covalent compounds of
12
tetraalkylPb (tetraethyl Pb), used as an additive octane enhancer for gasoline for
years.Industry fields most commonly utilize Pb in battery manufacturing and they can
produce up to 2.5 million tons of Pb every year (Wright & Welbourn, 2002). Pb is
distributed in soils from natural geological sources and airborne particles; mostly
resulted from gasoline combustion. The smaller the Pb particle size is, the farther it is
being scattered, thus contaminating a widersurface area. As Pb compounds are rather
insoluble and extremely immobile in soils and sediments, the discharges from
industrial activities that are being channeled into the river streams tend to settle down
rapidly into the bed sediments. This state of affair may affect sediment-dwelling
organisms and worst; enter the food chain by this route (Khan et al., 2007; Wright
&Welbourn, 2002).
Contamination of inorganic metal in the river, estuarine and marine sediment by
anthropogenic activities have been frequently detected and have drawn massive attention to
researchers around the world due to the risk effects caused to the aquatic life. Freshwater and
streambed sediments are the primary refuge for aquatic life. Many species of aquatic life such
as invertebrates make algae and bacteria as their source of food. Some of them feed on leaves
and organic matters which enters the river. Vertebrates like fish gain food and energy from
freshwater benthic macroinvertebrates. Macroinvertebrates are animal with no backbones
which are larger than 0.5 mm. They play an essential role in aquatic ecosystems as they leave
behind nutrient when they die which are reusable by other animals and aquatic plants in the
food chain (Duan et al, 2009). Figure 2.1 shows a photo of typical microinvertebrates in
different substrata.
13
Figure 2.1: Typical macroinvertebrates in different substrata(Duan et al, 2009)
Shrimp is one of the benthic community members in Niger Delta ecological zone of
Nigeria and most rivers in the world. They are among the most sensitive invertebrates when it
comes to contaminants exposure. It was proved in a study conducted by Ezemonyeet al.(2009)
which evaluated the toxic effects of an industrial detergent (Neatex) on shrimp for10 daysof
exposure. At the end of the study, they found that the exposure of various concentration of
Neatex to the shrimps had resulted immobilization and mortality. The surviving organisms
frequently moved out of the sediment and swam erratically in the overlying water as a sign of
stress.As a conclusion, the surfactant-containing chemicals discharge into the water column;
whether it is accidentally or intentionally discharge,could possibly jeopardize environmental
sustainability of this ecologically important benthic species (Ezemonye et al., 2009).
In 2006 to 2007, Yi et al. (2008) have investigated the concentration of heavy metals
(Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate in the middle
and lower reaches of the Yangtze River. The Yangtze River basin is severely contaminated
with 14.2 billion tons of waste water were discharged into it annually. Most of the waste
water is from industry and mining enterprises and the sewage of nearby cities where 80% of it
were discharged without proper treatment.In the study, they found that the heavy metal
concentration in sediment were higher than in the water by 100 to 10,000 times. On the other
hand, the concentrations of heavy metals in fish and invertebrate tissues were intermediate
between the sediment and the water samples.
The heavy metals concentration wasdistributed in the following order: bottom material
>demersal fish and benthic fauna > middle-lower layer fish > upper-middle layer fish >
water.Fish living near the river bed and making benthic invertebrates as their food source
possess a higher concentrations of heavy metals compared to fish living in the upper or
middle zones of the water column. The levels of Cu, Zn and Fe in fish were higher than Hg,
Pb, Cd, Cr, and As. This indicates that the fish are absorbing more necessary trace elements
(Cu, Zn and Fe) compared to the non-essentials elements.Heavy metals are accumulated
through the food chain via the following route: sediment - zoobenthos – benthonic sarcophagi
– human (Yi et al., 2008); as shown in Figure 2.2.
14
Figure 2.2: Heavy metals accumulation route (Yi et al, 2008)
The significance of the riverine, estuarine and marine sediment contamination by
inorganic metals has been emphasized in studies around the world due to the adverse
biological effects on the health of the aquatic environment. Contaminants originating from
urban, industrial and agricultural activities, atmospheric deposition and from natural
geological sources may accumulate in sediments up to several times the background
concentrations and may serve as the potential storage (> 90% of the heavy metal loads) for
both the inorganic and organic contaminants (Calmano, Hong, & Forstner, 1993). Therefore,
the buildup of potentially toxic metals carries a huge risk to the beneficial uses and
sustainability of the natural resources such as water, plants and aquatic animals.
Besides being the habitat for aquatic life, river is required in domestic, industrial and
agricultural applications. It is also one of the potable watersources in the world and a part of
an essential basicnecessity for healthy living. In Nigeria which has a population of about 170
million people, water pollution has been a great challenge as industrialization causes heavy
metals concentration to exceed the permissible limits. The concentration of heavy metals like
mercury, lead, cadmium, iron, cobalt, manganese, chromium, nickel, zinc, and copper often
exceed the maximum permissible limit recommended by standard organization of Nigeria and
World Health Organization. It is no longer safe for human consumption as it could lead to
various health impacts and mortality (Izah, Chakrabarty and Srivastav, 2016).
A study was conducted by Salem et al. (2000) on the relationship of heavy metals in
drinking water and their impact on human health. The drinking water samples were collected
from various areas from the Great Cairo Cities such as Heliopolice, El-Zaitoon, El-Mataria,
15
El-Salam, and El-Marg areas.The collected samples were from residential tap water of
patients who lived in these areas and diagnosed with renal failure, liver cirrhosis, hair loss,
and chronic anemia diseases. These samples were analyzed byusing ICP spectrometer (Perkin
Elmer ICP-400) and the method of Sam and Stanley 1963 was implemented to analyze urine
samples from all these patients to detect the possible presence of heavy metals in their urine.
The result of the study reveals that the contamination of drinking water supply to this
area is due to industrial wastes and agricultural activities. These anthropogenic activities
released hazardous and toxic materials in the groundwater thus contaminating the drinking
water supply. The study also shows that there are connections between the disease and the
contaminated drinking water. The disease of renal failure is related with drinking Pb- and Cd-
contaminated water supply, liver cirrhosis with Cu- and Mo-contaminated drinking water, hair
loss to Ni and Cr, and chronic anemia to Cu and Cd (Salem et al., 2000). Therefore, it is
proved that the presence of high level heavy metals in human drinks could threaten the health
of human being. Beside the above mentioned elements, there are several other harmful effects
caused by various heavy metals towards human’s health which are listed in Table 2.2.
Table 2.2: Harmful effects of several heavy metals on human health(Ali, et al., 2013)
Heavy metal Harmful effects
As As (as arsenate) is an analogue of phosphate and thus interferes with essential cellular processes such as oxidative phosphorylation and ATP synthesis
Cd Carcinogenic, mutagenic, and teratogenic; endocrine disruptor; interferes with calcium regulation in biological systems; causes renal failure and chronic anemia
Cr Causes hair loss
Cu Elevated levels have been found to cause brain and kidney damage, liver cirrhosis and chronic anemia, stomach and intestinal irritation
Hg
Anxiety, autoimmune diseases, depression, difficulty with balance, drowsiness, fatigue, hair loss, insomnia, irritability, memory loss, recurrent infections, restlessness, vision disturbances, tremors, temper outbursts, ulcers and damage to brain, kidney and lungs
Ni
Allergic dermatitis known as nickel itch; inhalation can cause cancer of the lungs, nose, and sinuses; cancers of the throat and stomach have also been attributed to its inhalation; hematotoxic, immunotoxic, neurotoxic, genotoxic, reproductive toxic, pulmonary toxic, nephrotoxic, and hepatotoxic; causes hair loss
16
Table 2.2 (continued): Harmful effects of several heavy metals on human health(Ali, et al.,
2013)
Heavy metal Harmful effects
Pb
Its poisoning causes problems in children such as impaired development, reduced intelligence, loss of shortterm memory, learning disabilities and coordination problems; causes renal failure; increased risk for development of cardiovascular disease.
Zn Over dosage can cause dizziness and fatigue.
Japan is one of the leading countries in industrialization and urbanization. During
1950s to1960s, Japan experienced a rapid economic growth and economic development
becomes the top priority. They hardly pay attention to environmental including water
resources. Industrial waste waterwas discharged into the river without proper treatment
resulting mercury contamination spread in the Minamata Bay. This irresponsible act resulted a
strange disease suffered by the community of Minamata. It was first found on a 7-year-old
little girl in late 1950s. She was diagnosed to suffer cerebral palsy at one private clinic, when
she was said to be malnourished by a municipal hospital pediatric department few days before
and diagnosed as infantile paralysis by another private clinic they visited five days before that.
The same mysterious symptoms were later suffered by several other patients in the
neighborhood and also to cats in this patients’ house. The cat started to be listless and curled
up. It staggers around in its cage a bit. Mild paralysis of the hind legs was observedwhen the
cat was allowed to walk outside. The cat’s symptoms progressed until one day, it ran around
in circles, gradually weakened, become completely listless, and lost all appetite. This
unknown disease with unknown cause was once called as “strange disease” back then and in
May 1956, it was called as “Minamata disease”. Now after 60 years of Minamata disease
outbreak, Japan still pay a high price on its economic growth and ignorance towards the
environment as there are still many patients suffering from the disease(Sugiyama, 2015).
Figure 2.3 shows on of the Minamata disease effect.
17
Figure 2.3: One of Minamata disease effect (Trust, 2010)
2.3 The Issues of River Contamination in Malaysia
Rivers in Malaysia have made immense contributions to the overall development of this
country. They have provided power generation, water for domestic, agricultural and industrial
consumption and have served as means of transportation and communication for the people.
Malaysia is gifted with rainfall and water resources. It is estimated that 566 billion m3 of
water running-off into the river system with an average rainfall of 3,000 mm each year
(Weng, 2005). In Malaysia, the major source of fresh water contributes some 97 per cent of
total water supply (Gasim, et al.,2009). The water is needed for drinking water supply,
sanitation, agriculture, industrialization, urbanization, fisheries, transportation, and recreation
and to produce hydroelectric power. The demand for water increases about 4% yearly and it is
estimated that about 20 billion per meter square (b/m3) of water is needed by the year
2020(Environment, 2005).
In Malaysia, like other countries in the world, the level of metal pollution in
freshwater bodies, especially the rivers, is no longer within safe limits for human
consumption. In year 2002, the Department of Environment (DOE) reported that industries
such as textile, metal finishing and electroplating, food and beverages, and animal feed could
not achieve more than 65% compliance. Some industries were operating either without
effluent treatment system (ETP) or with inefficient ETP. These industries had difficulties in
complying with parameters such as nickel, copper, lead, zinc and iron(Environment, 2002).As
a result, there is a gradual increase of heavy metal concentrations in sediment and water in
18
rivers which has reached alarming proportions. Statistics published by the Department Of
Environment for year 2004 revealed 8 per cent of our rivers to be polluted, 44 per cent
slightly polluted and the remaining 48 per cent to be clean (Kailasam, 2011). This indicates
that river basins in Malaysia are facing serious environmental problems.Figure 2.4 shows the
collection of Pahang River water sample to determine the level of bauxite.
Figure 2.4: The sample collection of Pahang River water for potential bauxite mining
pollution (Edward, 2016)
The trace metals in such waters may undergo rapid changes; affecting the rate of
uptake or release by sediments, thus influencing living organisms via the water sediment
chain. The levels of heavy metal concentration in river sediment in Malaysia have been
reported by other researchers. In the south region of Malaysia, the monitoring of heavy metal
concentration in Johor Strait (Danga Station and Pendas Station) has been polluted for
decades by chemicals or effluent from factories along the river. As observed through the years
of 1991, 2006, and 2009, the concentration of Zn in the Danga area was 31.428 ppm in 1991,
0.243 ppm in 2006 and 0.339 in 2009 while the concentration of Zn for the Pendas area were
16.092 ppm in 1991 to 0.753 ppm in 2009. The concentration of Cd in Danga Station ranged
from 0.0001 ppm in 2006 to 0.059 ppm in 1991 and up to 0.107 ppm in 2009. Pb
concentration for Danga Station in 2006 was 0.773 ppm, and 2.253 ppm in 2009, which
19
exceeded the required permissible level of 0.1 mg L−1 for Pb concentrations (Hadibarata, et
al., 2012).
It was also reported that the sediment inSkudai River, Johor Bahrucontains various
types of heavy metal such as As, Pb, Cr, Cu, Cd, Ni, Hg Sr, Y, Nb, Mo and Zn with the
concentration of most elements were in range of 1 ppm (parts per million) to 300 ppm
(Embong, 1998; Thanapalasingam, 2005). For the XRF analysis of Skudai River sediment,
the concentration of Zn, As and Pb have been found in the range of 210ppm -310 ppm, 10
ppm -40 ppm and 20 ppm- 50 ppm respectively (Embong, 1998). Meanwhile, in the east coast
region of Malaysia, it was reported that there were about 31elements (Al, Fe, K, Na, Mg, Ca,
Mn, Ba, Cr, Zr, Ni, Sr, Zn, Y, Li, Cu, Mo, Nb, Th, Co, Ga, W, Ta, Be, Ti, Ge, Se, Bi, Te, Sc
and Re) in Terengganu River basin which ranges from 0.05 μg/kg to 40.01 mg/kg(Sultan &
Shazili, 2010).
2.4 Remediation Techniques on Heavy Metals-Contaminated Soil and Sediment
Heavy metal contaminated sites are unusable resources until it is restored to a safer level. As
the concentrations of heavy metals in the environment increase rapidly from year to year,
cleaning them up from the contaminated soil is very crucial in order to detract their impact on
the ecosystems. The sites could be restored for beneficial practice with sufficient site
remediation planning and proper management of remediation technologies.Remediation of
soil contamination can be achieved by(Yeung, 2009b):
a) In-situ removal of contaminants from the contaminated site for further off-site
treatment of the contaminants removed
b) Ex-situ removal of contaminants from the contaminated soil after the soil has been
excavated from the contaminated site
c) In-situcontainment of the contaminants with the toxicity of the contaminants remains
unchanged but the contaminants are isolated from human contacts for a predetermined
period of time
d) Excavation of the contaminated soil and transport it to an engineered containment
system for long-term isolation
20
e) In-situtransformation of the contaminants so that the mobility and/or the toxicity of the
contaminants are significantly reduced so as to reduce the risk of soil contamination to
public health and the environment
f) Any combinations of these remediation mechanisms.
There are various methods such as amendments, washing, sand cap, flotation, ultrasonic-
assisted extraction, electrochemical remediation, phytoremediation and many more were
employed on the contaminated sites with the aim of remediating the contaminated soil and
sediment. Remediation is not only implemented to restore the soil and sediment for beneficial
use only, but it is also done to reduce its potential harmful effects towards living organisms.
The descriptions of some remediation techniques are discussed as follow:
2.4.1 Amendment
Amendment is one of the remediation techniques applicable on contaminated soil and
sediment. It could possess high cation exchange capacity (CEC), lower metal mobility and
bioavailability in sediment by precipitation or sorption, and decreasing their solubility.
Minerals like apatite, zeolites, steel shot, or beringiteare inexpensive amendment
andfrequently used during in situ metal immobilization.Compared to the amendments used in
soil, the one that was used in sediment usually has higher sorption capacity, lower water
solubility, higher stability under reducing and oxidizing conditions and lower cost (Peng et
al., 2008).
Amendment technique on sediment remediation is usually using apatite. It usually
formulated in the form of Ca10–a−bNaaMgb(PO4)6−x(CO3)xF2+0.4x with isomorphic substitution
of carbonate for phosphate, F for hydroxy, and minor substitution of Ca2+ by Na+ and
Mg2+atoms(Peng et al., 2008). During the remediation process, metal are incorporated with
Ca2+ in the lattice through ion exchange. Phosphate iscorrespondingly released as apatite are
dissolute in the reaction and forming a new metal-phosphate solid phase (such as
Ca10−xPbx(PO4)6(OH)2). Through this process, apatite minerals are able to mobilize almost
all Pb, Mn, Co, Cu, Cd, Zn, Mg, Ba, U, and Th in sediment (Peng et al., 2008).
21
2.4.2 Sandcap
Sand cap is a remediation technique which utilizes sandy material such as clean sediment,
sand or gravel as a capping in order to decrease the direct contact area between the
contaminated sediments with water. With this technique, the mobile and the exchangeable
metals are transformed from the contaminated sediment into the clean cap and combined with
particles in more stable forms. The heavy metal concentration in water could be reduce for up
to 80% by placing the coarse-grained cap, provided if the thickness is approximately 50 cm
(Peng et al., 2008).
This inexpensive method is a good selection for contaminated sediment remediation to
reduce transfer rate of metal in sediment but has a small immobilization effect of heavy metal.
Thus, this method is usually coupled or assisted with some other kind of remediation
technique such as amendment (such as apatite, rock phosphate, lime or zeolite) to enhance its
effectiveness(Peng et al., 2008).Figure 2.5 shows the work of sand cap remediation technique.
Figure 2.5: The work of sand cap remediation technique (J. F. Brennan Co. Inc.
2013)
2.4.3 Washing
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A simple ex situ of sediment washing remediation technique involves adding washing water
to the dredged sediment and heavy metals are transferred to the wash solution. This method is
usually applied on sands, gravels, or weaker bound metals in the form of exchangeable,
hydroxides, carbonates and reducible oxides fraction. Several additives such as acid washing
(e.g. H2SO4 and HNO3), chelating agents (e.g. EDTA, DTPA and EDDS) or surfactants (e.g.
rhamnolipid) are utilized in order to improve the performance of sediment washing (Peng et
al., 2008).
As for soil washing, it could be used as a pretreatment process to reduce the volume
of feedstock for other remediation technology. Initially, the excavated soil was mechanically
screened to remove various oversize materials, and separated to generate coarse- and fine-
grained fractions of the contaminated soil. The separated soil was then treated by individual
fractions, i.e. soil washing and management of the residual generated. The extracting fluid
requires further treatment afterwards to remove and destroy the contaminants (Yeung,
2009b).Figure 2.6 shows a typical process diagram of soil washing remediation technique.
Figure 2.6: Typical process diagram of soil washing remediation technique (HBR
Limited, 2013)
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Some remediation technology such as soil washing requires the usage of chemical
solutions in decontaminating the polluted area. In watertight or low permeable soil area, the
possibility of insufficient reagent penetration through the soil has become the major limitation
of this remediation process. For some other processes such as stabilization, solidification and
vitrification, the texture and property of soil mass may change due to the extreme or intense
treatment implemented. The post treatment soils are sometime unfit for agriculture or natural
preserve purpose.
Besides removing or decontaminating pollutant from the soil, there are treatments that
choose to only stabilize the heavy metal in its particular area such as stabilization and
solidification, bioremediation and vitrification. However, this kind of remediation technique
has a potential of heavy metal mobility in future (Cameselle, Chirakkara, & Reddy, 2013).
Every remediation technology requires much energy usage besides its long term application
and high cost demand. Among all these frequently applied methods, phytoremediation
emerges to be a great green solution to the problems of heavy metals contamination in soil,
rivers and sediments due to its low expenses and suit to be applied in large scale of in situ
application.
2.5 Phytoremediation
The term “phytoremediation” is a combination of two words; a Greek word “phyto” means
“plant” and a Latin word “remedium” means “to correct or remove an evil” (Ali, et al., 2013).
Phytoremediation is the use of living green plants for in situ risk reduction and/or removal of
contaminants from contaminated soil, water, sediments, and air. Phytoremediation can be
defined as destruction, inactivation, or immobilization of pollutant in an undamaging form,
which is primarily mediated by photosynthetic plants (Terry & Banuelos, 2000). Specially
selected or engineered plants are employed in the process. Plants that suit to hold the role of a
phytoremediator should possess the ability to accumulate the target metal(s) in its above-
ground parts (shoots) and able to withstand the concentration of metal accumulated in its
tissues. In addition to that, a fast growth plant with highly effective (i.e. metal accumulating)
biomass and easily harvestable would also an ideal candidate for the phytoremediation
process (Kärenlampi, et al., 2000).
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2.5.1 Techniques of phytoremediation
Fundamental and applied research has unambiguously validated that selected plant species
own the genetic potential to remove, degrade, metabolize, or immobilize a wide range of
contaminants by different process based on the nature of their remediation process known as
phytoextraction, rhizofiltration, pythostabilisation, phytovolatilization, phytodegradationand
phytodesalination(Anjum, et al., 2013; Raskin & Ensley, 2000). Each technique demonstrates
different ways a plant could be utilized to remediate contaminant from its sources. Figure 2.7
illustrates the techniques of phytoremediation process.
Figure 2.7: Techniques of phytoremediation process(Cameselle et al., 2013)
The descriptions of each technique are summarized in Table 2.3. In this research, the
focus will be given to phytoextraction which is the use of metal-accumulating plants that can
transport, translocate and concentrate metals from the contaminated soil to the roots and
aboveground shoots (Raskin & Ensley, 2000; Terry & Banuelos, 2000). This remediation
technique is implemented to recover metals from contaminated soils using inedible crops
(Anjum, et al., 2013). A plant that is unattractive to animal is suitable for phytoextraction in
order to minimize the potential risk of transferring the metals to the higher trophic level of
terrestrial food chain. Most importantly, the plant used for phytoextraction should have high
metal tolerance and able to accumulate metal in a large amount (Thangavel & Subbhuraam,