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UNIVERSITI PUTRA MALAYSIA
TREATMENT OF SYNTHETIC WASTEWATER USING HORIZONTAL SUBSURFACE FLOW CONSTRUCTED WETLAND
SANAZ SARAFRAZ
FK 2008 94
TREATMENT OF SYNTHETIC WASTEWATER USING HORIZONTAL
SUBSURFACE FLOW CONSTRUCTED WETLAND
By
SANAZ SARAFRAZ
GS16334
Thesis Submitted to the School of Graduate Studies, University Putra Malaysia, in Fulfilment of the Requirement for the Degree of Master of Science
September 2008
ii
Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science
TREATMENT OF SYNTHETIC WASTEWATER USING HORIZONTAL
SUBSURFACE FLOW CONSTRUCTED WETLAND
By
SANAZ SARAFRAZ
September 2008
Chairman: Associate Professor Dr. Thamer Ahmed Mohamed, PhD
Faculty: Engineering
Constructed wetland is an effective wastewater treatment technology which is used
in worldwide. Nevertheless, the effectiveness of using this wastewater treatment is
depending on the selection of the type of design used and other factors. This research
was conduced to test the influence of media and vegetation subsurface flow
constructed wetlands, designed based on the first-order plug flow kinetics. In this
study, four horizontal subsurface flow wetlands (HSSF), each with dimensions of 1.3
m (L) × 0.5 m (W) ×0.4 m (D), were constructed at the Research Station of Tehran
University, located in Karaj, Iran. The study was carried out from April to
September, 2007. Gravel and zeoilte were used in this study as substrate. Gravel-
beds with and without plants, and gravel-beds mixed with 10% zeolite, with and
without plants were examined to investigate the feasibility of treating synthetic
wastewater which was specially produced and modified to imitate agricultural
wastewater. The average synthetic influent wastewater contained approximately 100
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mg l-1 Nitrate (NO3-N), 10 mg l-1 total Phosphorous, 10 mg l-1 Zn (II), 2 mg l-1 Pb (II)
and 1 mg l-1 Cd (II), while the macrophytes selected were Phragmites Australis and
Juncus Inflexus in combine with each other. Water discharge was 65 l / day for each
cell, and retention time (HRT) was 1.4 d. The influent and effluent Zn, Pb, Cd, P and
NO3-N concentrations were monitored and analyzed every 15 days to assess the
performance of the wetland units for removal efficiencies based on the statistical
analyses. Two intermediate samples were also collected from each cell to evaluate
the values of pollutant concentrations, the parameters along the units, and the effect
of the HRT. At the end of the study, plants were harvested and analyzed for the
same factors (NO3, P, Zn, Pb and Cd).
The results derived indicated that the system had acceptable and optimal pollutant
removal efficiency, and that both plants were found tolerant under the tested
conditions. The wetland system could achieve the NO3-N removal of 79.19% in
vegetated cell with gravel and 10% zeolite as substrate, and 86.58% in an
unvegetated cell with gravel and 10% zeolite as substrate, and 82.39% in vegetated
cell with gravel as substrate, and finally 87.94% in unvegetated cell with gravel as
substrate. As for the P removal, the efficiencies of 93.12%, 89.47%, 81.76% and
76.65% were respectively achieved for the vegetated cell with gravel and zeolite as
substrate, the vegetated cell with gravel as substrate, unvegetated cell with gravel and
zeolite as substrate, and unvegetated cell with gravel as substrate. The outflow
concentrations of Pb and Cd were found to be under the detection limit; however, as
for Zn, the removal efficiencies of 99.9%, 99.76%, 99.71% and 99.52% were
concluded for the vegetated cell with gravel and zeolite, unvegetated cell with gravel
and zeolite, vegetated cell with gravel, and unvegetated cell with gravel, respectively.
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Keywords:
Constructed Wetland, Nitrate-Nitrogen, Phosphorus, Wastewater, Zeolite, Zn
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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains
RAWATAN AIR KUMBAHAN SINTETIK MENGGUNAKAN ALIRAN
MENDATAR PERMUKAAN BAWAH TANAH LEMBAP
Oleh
SANAZ SARAFRAZ
September 2008
Pengerusi: Profesor Madya Dr. Thamer Ahmed Mohamed, PhD
Fakulti: Kejuruteraan
Pembinaan kawasan tanah lembab adalah teknik yang sangat berkesan untuk rawatan
air kumbahan dan telah digunakan dengan meluas diseluruh dunia.
Walaubagaimanapun keberkesanan penggunaan teknik ini bergantung kepada
pemilihan jenis rekabentuk dan beberapa factor lain. Penyelidikan ini telah
dijalankan untuk menguji kesan jenis media dan tumbuhan keatas 4 jenis aliran
mendatar bawah tanah bagi rekabentuk tanah lembab berdasarkan first order plug
flow kinetics. Dalam kajian ini, 4 jenis aliran rekabentuk aliran mendatar bawah
tanah untuk tanah lembab (HSSF), 1.3 m (L) x 0.5 m (W) x 0.4 m (D), telah dibina di
Pusat Penyelidikan, Tehran University yang terletak di Karaj, Iran. Kajian ini telah
dijalankan bermula dari bulan April hingga September 2007. Didalam kajian ini batu
kelikir dan zeoilte telah digunakan sebagai lapisan bawah. Lapisan batu kelikir
dengan tumbuhan dan tanpa tumbuhan, dan juga lapisan batu kelikir yang dicampur
dengan 10% zeolite dengan tumbuhan dan tanpa tumbuhan telah dikaji untuk
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mengkaji kemungkinan merawat air kumbahan sintetik yang dibuat dan diubahsuai
khusus supaya serupa dengan cirri-ciri air kumbahan pertanian. Purata sisa air
kumbahan mengandungi lebih kurang 100 mg 1-1 Nitrat (No3-N), 10 mg 1-1 jumlah
Phosphorous, 10 mg 1-1 Zn (II), 2 mg 1-1 Pb (II) dan 1 mg 1-1 Cd (II), sementara
macrophytes yang dipilih adalah Phyragmites Australis dan Juncus Inflexus
digabungkan bersama. Luahan air adalah 781 d-1 untuk setiap sel dan masa tahanan
hidraulik (HRT) adalah 1.2 d. Kepekatan luahan masuk dan keluar Zn, Pb, Cd, P dan
NO3-N diperhatikan dan dianalisa setiap 15d untuk mengakses pencapaian
kecekapan setiap unit tanah lembab berdasarkan analisa statistik. Dua sampel
perantaraan juga dikutip untuk setiap sel bagi dinilai kadar kepekatan bahan enap
cemar, parameter-parameter unit dan kesan masa tahanan hidraulik (HRT).
Dipenghujung kajian tumbuh-tumbuhan dituai dan analisa keatas NO3, P Zn, Pb dan
Cd dilakukan.
Keputusan yang diperolehi menunjukkan sistem mempunyai tahap penerimaan dan
tahap kecekapan penyingkiran bahan enap cemar yang optimum dan kedua-dua
tumbuh-tumbuhan didapati mampu bertahan dibawah keadaan dimana kajian
dijalankan. Sistem tanah lembab tersebut mampu mencapai tahap penyingkiran NO3-
N sehingga 79.9% dalam sel berbatu kelikir yang ditumbuhi tumbuh-tumbuhan, 10%
zeolite sebagai lapisan strata bawah dan 86.58% dalam sel berbatu kelikir tanpa
tumbuh-tumbuhan serta 10% zeolite sebagai lapisan strata bawah dan 87.94% dalam
keadaan tanpa tumbuh-tumbuhan dengan batu kelikir sebagai lapisan strata bawah.
Tahap penyingkiran P pula ialah 93.12%, 89.47%, 81.76% dan 76.65% masing-
masing diperolehi dari sel dengn tumbuh-tumbuhan dengan batu kelikir dan zeolite
sebagai lapisan strata bawah, sel dengan tumbuh-tumbuhan dan batu kelikir sebagai
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lapisan strata bawah, sel tanpa tumbuh-tumbuhan dengan bati kelikir dan zeolite
sebagai lapisan strata bawah dan sel tanpa tumbuh-tumbuhan dengan batu kelikir
sebagai lapisan strata bawah. Kepekatan luahan Pb dan Cd pula didapati dibawah
tahap yang boleh dikesan, bagaimanapun bagi Zn, tahap kecekapan penyingkiran
sebanyak 99.9%, 99.7%, 99.71% dan 99.52% dapat disimpulkan untuk keadaan sel
masing-masing dengan tumbuh-tumbuhan dengan batu kelikir dan zeolite, sel tanpa
tubuh-tumbuhan dengn batu kelikir dan zeolite, sel dengan tumbuh-tumbuhan
dengan batu kelikir, dan sel tanah tumbuh-tumbuhan dengan batu kelikir.
Kata Kunci:
Tanah lembab yang dibina, Nitrat-Nitrogen, Phosfur, Air kumbahan, Zeolite, Zn
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DEDICATION
I wish to dedicate this thesis to my beloved country, Iran
And
To my parents, Manouchehr Sarafraz and Afsaneh Parhami
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ACKNOWLEDGEMENTS
I am ever grateful to God, the Creator and the Guardian, and to whom I owe my very
existence.
It is a pleasure to thank the people who made this thesis possible.
Firstly I would like to thank my Iranian supervisor Dr. Abdolmajid Liaghat, head of
Irrigation and Reclamation Department of Tehran University, for providing the
opportunity to go on my research in my country, Iran. He always found time to speak
with me offering guidance, support and encouragement in light of his busy schedule.
I would like to gratefully acknowledge the supervision of Dr. Thamer Ahmed
Mohammad during this work. I also thank Prof. Megat Johari as my co-supervisor. I
wanted to specially thank them for being agreed with continuing my research in Iran
and making all necessary supports.
I would like to say a big 'thank-you' to the people of Malaysia whom helped me not
feeling homesick and alone. With their kind and calm faces and many nice places they
gave me a reason to miss Malaysia.
I wish to thank my best friends, Sara, Nooshin and Samaneh, for helping me get
through the difficult times, and for all the emotional support and nice moments we
had in Malaysia together.
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I wish to thank my my brother, Yashar and my sister, Sepideh for providing a loving
environment for me.
Most importantly, I wish to thank my parents. They bore me, raised me, supported
me, taught me, and loved me. To them I dedicate this thesis.
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I certify that an Examination Committee has met on 25th September 2008 to conduct the final examination of Sanaz Sarafraz on her Master of Science thesis entitled “Treatment of synthetic wastewater using horizontal subsurface flow constructed wetland” in accordance with Universiti Pertanian Malaysia (higher degree) act 1980 and Universiti Pertanian Malaysia (higher degree) Regulations 1981. The Committee recommends that the student be awarded the Master of Science. Members of the Examination Committee were as follows: Bujang Kim Huat Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Azni Idris Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Abdul Halim Ghazali Associate Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Hamidi Abdul Aziz Professor Campus of engineering Universiti Sains Malaysia (External Examiner) HASANAH MOHD. GHAZALI, PhD
Professor and Deputy Dean School of Graduate Studies
Universiti Putra Malaysia
Date:
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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of supervisory committee were as follows: Thamer Ahmed Mohamed, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman)
Megat Johari Megat Mohd. Noor, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Member)
HASANA MOHD. GHAZALI, PhD Professor and Dean
School of Graduate Studies Universiti Putra Malaysia
Date: 18 December 2008
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DECLARATION
I declare that the thesis is based on my original work except for quotations and citations which have been duly acknowledged. I also declare that it has not been previously and is not concurrently submitted for any other degree at UPM or at any other institutions.
……………………..
SANAZ SARAFRAZ
Date: 12 March 2009
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TABLE OF CONTENTS
ABSTRACT II
ABSTRAK V
DEDICATION VIII
ACKNOWLEDGEMENTS IX
DECLARATION XIII
TABLE OF CONTENTS XIV
LIST OF TABLES XVII
LIST OF FIGURES XVIII
LIST OF ABBREVIATIONS XX
CHAPTER I 1
INTRODUCTION 1
1.1 General 1
1.2 Statement of the problem 2
1.3 Objectives of the Study 4
CHAPTER II 5
LITERATURE REVIEW 5
2.1 Natural Wetlands 5
2.2 Constructed Wetlands (CW) 6
2.3 The Functions of Wetland 8
2.4 Advantages of Constructed Wetlands 9
2.5 Limitations of Constructed Wetlands 10
2.6 The Types of Constructed Wetlands 11 2.6.1 Free Water Surface Wetlands (FWS) 11
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2.6.2 Subsurface Flow Wetlands (SSF) 11 2.6.3 The Differences of the FWS and SSF 13
2.7 Wetland Vegetation 14 2.7.1 General 14 2.7.2 Free Floating Macrophytes 15 2.7.3 Submerged Macrophytes 16 2.7.4 Emergent Macrophytes 17
2.8 Wetland Substrate 21 2.8.1 General 21 2.8.2 Soil 21 2.8.3 Sand and Gravel 22 2.8.4 Zeolite 23
2.9 Wetland Micro-organisms 24
2.10 Wastewater 25
2.11 Removal Mechanisms in CWs 28 2.11.1 Nitrogen Removal 28 2.11.2 Phosphorus Removal 35 2.11.3 Heavy Metal Removal 37 2.11.4 BOD Removal 40
2.12 Constructed Wetlands Design 41 2.12.1 General Design 41 2.12.2 The Design Model for the BOD Removal in Subsurface Flow CWs 44 2.12.3 The Design Model for the TSS Removal in Subsurface Flow CWs 44 2.12.4 The Design Model for the Nitrate Removal in Subsurface Flow CWs 45
CHAPTER III 47
MATERIALS AND METHODS 47
3.1 Description of the Site 47
3.2 Design 48 3.2.1 Type of Wetland 48 3.2.2 Wetland Size 48 3.2.3 Aspect Ratio and Slope 49 3.2.4 Inlet and Outlet 49 (c) 54 Figure 3.9 The perspective view of the wetland cell 55 3.2.5 Liners 55 3.2.6 Substrate 55 3.2.7 Vegetation 56 3.2.8 Construction Procedure 57 3.2.9 Wastewater 61
3.3 Methods 63
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3.3.1 Constructed Wetland and Its Variations 63 3.3.2 Wastewater Inflow 65 3.3.3 Wastewater Sampling 67 3.4 Statistical Analysis 68
CHAPTER IV 69
RESULTS AND DISCUSSION 69
4.1 The Overall Performance of the SSF 69
4.2 The NO3-N Concentrations in Inflow and Outflow Wastewater 75
4.3 P Concentrations in Inflow and Outflow Wastewater 80
4.4 Heavy Metals Concentrations in Inflow and Outflow Wastewater 83
4.5 Variations along the SSF CW Length 87 4.5.1 The Variation of NO3-N 88 4.5.2 The Variation of P 90 4.5.3 The Variation of Heavy Metals 92
4.6 NO3, P, Zn, Pb and Cd Concentrations in Substrate 94
4.7 The Concentrations of NO3, P, Zn, Pb and Cd in Plants 96
CHAPTER VI 100
CONCLUSIONS 100
5.1 Conclusions 100
5.2 Recommendations 103
REFRENCES 105
APPENDICES 116
BIODATA OF THE AUTHOR 135
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LIST OF TABLES
Table Page 2.1 Wastewater Characteristics (Metcalf and Eddy, 2005) 27
2.2 Nitrogen transformations in constructed wetlands (Vymazal, 2007) 30
3.1 Karaj fields wastewater characteristics 61
3.2 influent concentrations of artificial wastewater 62
4.1 Meteorological data during the operation period 69
4.2 The Total Concentrations of the Inflow and Outflow, 72
Together with Standard Deviation (S.D.), Range and Removal Efficiency
4.3 T-test Confidence Interval for the Comparison of 75
Mean Values of Inflow and Outflow
4.4 Mean, S.D., Range and Removal (%) of Treatment Values 87
along the Length of the Cells
4.5 Pollutants in the Substrate of Cells 94
4.6 The Amount of Biomass Accumulated in each Cell 96
4.7 The Concentrations and Percentages of Nutrients 97
and Heavy Metals in Plants
4.8 Studied Elements Accumulated in the Plants of each Cell 99
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LIST OF FIGURES
Figure Page 2.1 The Schematic of Constructed Wetland 12
3.1 Wetland Cell 49
3.2 Control Structure (left) and the float (right) 50
3.3 Inlet Zone 51
3.4 Wastewater Container 51
3.5 Outlet Zone 52
3.6 Riser 52
3.7 Pizometers 53
3.8 Plan and Section View of the Wetland Cell 54
3.9 Perspective View of the Wetland Cell 55
3.10 Phragmites Australis (left) and Juncus Inflexus (right) 56
3.11 Akhtarabad Reed-bed 57
3.12 The allocation of the cell 57
3.13 The arrangement of the cell 58
3.14 Substrate Design Stage 59
3.15 Plant Transplanting 59
3.16 The side layout of the wetland 60
3.17 The layout and compartments of CWs 63
3.18 Schematic Plan of the System 64
3.19 Sampling Points in the Cells 67
4.1 Cell’s Contents 70
4.2 A Wetland Cell in the Beginning and at the End of the Operation Period 71
4.3 An opposite View of the CWs at the End of the Operation 71
4.4 Removal Efficiency of NO3-N, P and Zn in A, B, C and D Cells 73
4.5 NO3-N Removal Efficiency 76
4.6 Inflow and Outflow Concentration of NO3-N during the Operation Period 77
4.7 NO3-N Outflow Concentrations in each Cell during the Study Period 78
4.8 P Removal Efficiency 80
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4.9 Inflow and Outflow Concentration of P during the Operation Period 81
4.10 P Outflow Concentrations in each Cell during the Study Period 82
4.11 Zn Removal Efficiency 84
4.12 Inflow and Outflow Concentration of Zn during the Operation Period 85
4.13 Zn Outflow Concentrations in each Cell during the Study Period 86
4.14 Changes in NO3-N Mean Concentration along the Length of the Cells 88
4.15 Changes in NO3-N Concentration along the Length of the Cells. 89
4.16 Changes in P Mean Concentration along the Length of the Cells 91
4.17 Changes in P Concentration along the Length of the Cells in each 91
Sampling Time at 3 Points
4.18 Changes in Zn Mean Concentration along the Length of the Cells 92
4.19 Changes in Zn Concentration along the Length of the Cells in each 93
Sampling Time at 3 Points
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LIST OF ABBREVIATIONS
Abbreviations
BOD
Cd
CW
d
D
EPA
ET
FWS
HLR
HRT
Kt
Kg/g
L
mg
N
NO3-N
°C
P
Pb
pH
ppm
Meaning
5day Biochemical Oxygen Demand
Cadmium
Constructed Wetland
Day
Depth
Environmental Protection Agency
Evapotraspiration
Free Water Surface
Hydraulic Loading Rate
Hydraulic Retention Time
1st Order Rate Constant
Kilogram/gram
Length/Liter
Milligram
Nitrogen
Nitrate- Nitrogen
Degrees Celsius
Phosphorus
Lead
Acidity
Parts Per Million
xxi
PVC
RZE
SSF
TSS
TP
TKN
W
WW
Zn
Polyvinyl Chloride
Root Zone Effect
Subsurface Flow
Total Suspended Solids
Total Phosphorus
Total Kjeldahl Nitrogen
Wide
Wastewater
Zinc
CHAPTER I
INTRODUCTION
1.1 General
There are 80 countries and regions which are experiencing water stress all around the
world; out of which 30 countries are suffering water scarcity during a large part of the
year, and exploiting reserves which are being not sufficiently replaced (Gleick, 1993).
Iran is also going to experience water scarcity by 2025, based on the availability of
less than 1000 m3 of renewable water per person per year (Kivaisi, 2001). The
depletion of reserves and competition for water usage between the nations, as well as
among various sectors such as agriculture, industry and municipalities, has imposed
the major reasons leading to water scarcity.
Iran is a country with an area of 648,000 km², in which arid and semi-arid climate
has covered a great area of the lands. The average of its annual precipitation is about
240 mm, which is less than one third of the average precipitation of the world.
2
1.2 Statement of the problem
Due to the occurrence of draught in 2001, population growth, urbanization and
industrial development, the need for water use has been increased in Iran
(Hassanoghli, 2003).
On the contrary to the rising needs, the amount of renewable water resources has
been reduced in the last few years. Statistics shows that this amount was decreased
from 5500 m3 in 1960 to 2100 m3 in 1997, to 1750 m3 in 2005, and this is expected
to be only 1300 m3 in 2020 (Iran Statistical Centre, 2006).
The minimum acceptable renewable water resources demand for a standard life is
2000 m3 per year per capita (Bouwer, 1994). According to water usage amount and
the population increase, the water demand in Iran is expected to be 126×10 9 m3 in
the year 2010, and this will be 150×10 9 m3 in 2020 (Hassanoghli, 2003).
In addition to the natural scarcity of freshwater, the quality of the available freshwater
is also getting worse; this is due to pollution which is a result of water shortage.
Today, it is reported that more than 5 million people die each year throughout the
world from various illnesses because of drinking poor quality water (Kivaisi, 2001).
In Iran, pollution resulting from agricultural wastewater is increased, a scenario which
is harmful for both human being and environment. The main sources of agricultural
wastewater include silage leachate, manure runoff, pesticide runoff and farmyard
runoff. The recognitions of the impacts of these pollutants on the environment have
led to the improvement of wastewater treatment systems.
3
Agricultural and residential wastewaters contain high levels of nutrients and if not
treated, they can contaminate surface water and groundwater systems.
During the last two decades, various experiments have been taken to reduce the
nutrient transport from agricultural activities. The best identified management
practices are increasingly used to reduce the input of nutrients to the agricultural
fields and the leakage from the fields. At the same time, different water treatment
approaches such as wetlands are also used to decrease the transport of nutrients from
land to the sea (Johansson et al., 2004). The management for water usage and water
demand, using recycled water and wastewater, as well as using water and wastewater
treatment programs are some of these solutions.
The treatment of wastewater using constructed wetland is one of the treatment
systems which is used in many parts of the world. This system seems to have the
potential to be one of the solutions in discharging the huge amount of wastes and
getting access to safer drinking water.
Although CWs have not been widely adopted in Iran, they can be preferred system
for wastewater treatment due to the existence of many natural wetlands and
capability of many areas for constructing artificial wetlands to treat different kinds of
wastewaters. They are effective in treating pollutants by combining biological,
chemical and physical treatment processes (Crites, 1994).