constructed wetlands as an appropriate treatment of landfill leachate

153 Pages·2011·2.42 MB·English

CONSTRUCTED WETLANDS AS AN
APPROPRIATE TREATMENT OF
LANDFILL LEACHATE
by
Elizabeth Colomb Bricken
Submitted as the dissertation component (which counts for fifty percent
of the degree) in partial fulfillment of the academic requirements for the
degree of
Masters of Science
in the School of Life and Environmental Science
University of Natal
Durban, South Africa
September 2003
ii
ABSTRACT
One of the main environmental problems associated with the disposal of waste on land is the
release of liquid emissions from the site. This wastewater, known as leachate, is a product of
the biodecomposition of the waste and filtrates from the landfill once the moisture saturation
of the fill has been reached. The chemical composition of leachate is variable over time and
between sites. Regardless of these variables, the main pollutants of concern in the leach ate
are ammonia and organics, both of which can cause environmental degradation in relatively
low concentrations. Worldwide and in South Africa, leachate has either been directly
released into the environment or into the local domestic sewage system. As more has been
learned about the human and environmental health risks associated with these disposal
methods, there has been a new focus in waste management toward treating the leach ate at
the source as part of the broader focus of sustainable landfilling. One of the treatment
options being used is constructed wetlands (CW) due to the physical and chemical
transformation mechanisms in these biological systems. This treatment process has been
demonstrated to be effective as a final polishing treatment for leachate, and it is considered
a technology appropriate in the South African context. Therefore the aim of dissertation is to
ascertain the use of constructed wetlands as an appropriate treatment option for untreated
methanogenic landfill leachate by determining the efficiency of ammonia and organic
removal in a pilot-scale vegetated submerged bed (VSB) constructed wetland (CW) planted
with Phragmites austra/is. During the 22-week treatability trial the VSB achieved an
ammonia concentration removal efficiency of 91 % and mass removal efficiency of 87%.
Despite this substantial reduction of ammonia, the VSB was unable to achieve the required
discharge standard. There were erratic fluctuations in both the treatment efficiencies for
COD and BOO, and the results show no evidence of constant reduction of organics during
the treatability trials. This is due to the refractory nature and the low biodegradability of the
organics that remain in methanogenic leachate as suggested by the low BOO to COD ratio.
Due to the low biodegradability of the organics, a biological treatment system, such as a
VSB, will not be able to reliably meet the required discharge standards. Other passive
treatment options or a combination of systems need to be explored in order to both satisfy
legislative requirements and be appropriate in the South African context.
iii
DEDICATION
This dissertation, like my life, is dedicated to the Glory and Love of God to whom I will be
forever thankful for welcoming His prodigal daughter back home and for giving purpose to
my life.
I was pushed back and about to fall,
but the Lord helped me.
The Lord is my strength and my song;
He has become my salvation
You are my God and I will give You thanks.
You are my God and I will exalt You.
-Psalm 118:13-14, 28
iv
PREFACE
The experimental work described in this dissertation was carried out in the School of Life &
Environmental Sciences, University of Natal, Durban, South Africa, from January 2003 to
August 2003 under the supervision of Professor Gerry Garland and Dr. Cristina Trois.
These studies represent original work by the author and have not otherwise been submitted
in any form for any degree or diploma to any tertiary institution. Where use has been made
of the work of others it is duly acknowledge in the text.
Elizabeth Colomb Bricken
September 2003
v
ACKNOWLEDGEMENTS
The desire to experience part of Africa has always pulled on my spirit, but I would not have
been able to fulfill this dream in such a meaningful way without the Ambassadorial
Scholarship from the Rotary Foundation. I am indebted them and to the Tullahoma Noon
Rotary Club and the Rotary District 6780 in Tennessee for selecting me to represent them as
their Ambassador of Goodwill. Thank you for allowing me to be a part of your mission to
further international understanding.
I arrived in South Africa knowing no one but was greeted at the airport by what was to be my
surrogate African family. So to Sihawu, Nonhlanhla, Lindani and Sabelo Ngubane -
ngiyabonga kakhulu! I will never be able to thank you enough for welcoming into your home
and allowing me to be part of your family.
My thanks goes out to Kebreab Habte and Mark Griffith for letting the geo-parasite share
your space. I am grateful for the friendship and the chance to learn as much about South
African and Eritrean culture as I did my dissertation!
Many thanks to Dr. Cristina Trois and Prof. Gerry Garland for helping me navigate through
the academic bureaucracy and the world of landfills and leachate.
To Christoph Nzuzu, Blessing Ncube, Albert Khuzwayo and the rest of the guys at the
Bisasar Road La ndfill , thanks for all your assistance with my project and making working at a
landfill a rather enjoyable experience.
There are a few things that I never expected when I arrived in South Africa, and one of them
was hearing the familiar music from Appalachia. I was pleasantly surprised when I found
four others around Durban who also love the sound of bluegrass. To each of the members
of the Bandits, Bryan Eaton, Jack Todd, Cara Malan, and Craig Martens, thanks for all the
pickin' and grinnin' and for lettin' me sing wid ya.
And finally, to my parents, Rush and Belinda Bricken, and my siblings, Benjamin, Bradford
and Blair Bricken, I truly cannot find words strong enough to thank you for all you continue to
give me. I would not have had the courage to venture out without the knowledge of your love
and your prayers. God has blessed me with you and I am so thankful.
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TABLE OF CONTENTS
Title Page
Abstract ii
Dedication iii
Preface iv
Acknowledgements v
Table of Contents vi
List of Tables x
List of Figures xi
List of Plates xii
Chapter One -Introduction
1.1 Overview of Landfills and Leachate
1.2 Leachate Treatment in South Africa 2
1.3 Long-term solution to landfill leach ate 3
1.4 Aim and Objectives 4
Chapter Two - Landfills and Leachate
2.1 Overview of Landfills and Leachate 5
2.1.1 Landfills in Waste Management 5
2.1.2 Leachate 6
2.2 Leachate Generation 7
2.2.1 Climatic conditions 8
2.2.2 Geohydrology 9
2.2.3 Hydraulic properties and self-generating factors 9
2.2.4 Water Balance and Leachate Generation 10
2.3 The Effect of Waste Decomposition on Leachate 10
2.3.1 Aerobic Degradation Phase (Phase 1) 11
2.3.2 Acetogenic Phase (Phase 11) 12
2.3.3 Anaerobic Transitory Phase (Phase Ill) 13
2.3.4 Methanogenic Phase (Phase IV) 14
2.3.5 Final Aerobic Phase (Phase V) 14
2.3.6 General Leachate Characteristics 15
2.4 Factors that effect leachate composition 16
2.4.1 Factors that effect degradation 16
2.4.2 Landfill Managements Effect on Leachate Composition 17
2.5 Constituents in Leachate and Their Environmental and Health Impacts 18
2.5.1 Nitrogen 20
2.5.2 Ammonia 21
2.5.3 Nitrate/Nitrite 23
2.5.4 Organic Nitrogen 24
2.5.5 Organics 24
vii
2.5.6 Phosphorus. 26
2.5.7 Alkalinity 27
2.5.8 pH 27
2.5.9 Electric Conductivity 28
2.6 Treatment and Management Options for Landfill Leachate 28
2.6.1 Chemical treatment methods 29
2.6.1.1 Coagulation and Flocculation 29
2.6.1.2 Ozonation 30
2.6.1.3 Carbon Absorption 30
2.6.1.4 Chemical oxidation 31
2.6.2 Physical separations 31
2.6.2.1 Filtration 31
2.6.2.2 Evaporation 32
2.6.2.3 Air stripping 32
2.6.3 Biological Treatment 33
2.6.3.1 Attached Growth -Aerobic Treatment 33
2.6.3.2 Non-Attached Growth Aerobic Treatment 34
2.6.3.3 Anaerobic biological treatment 34
2.6.4 Management Options 35
2.6.4.1 Discharge to the sewer 35
2.6.4.2 Recirculation back into the landfill 35
2.6.4.3 Land treatment via spray irrigation 35
2.7 Landfill Management 36
2.7.1 Uncontrolled release 37
2.7.2 Encapsulation 38
2.7.3 Containment and collection 39
2.7.4 Controlled attenuation 39
2.7.5 Flushing bioreactor 40
2.7.6 Landfill management and leach ate treatment 41
Chapter Three - Legislative Framework
3.1 Introduction 42
3.2 Connection of Regulations to Leachate Treatment 43
3.3 Reason for legislation 44
3.4 Landfill and Leachate Legislation in South Africa 44
3.4.1 Landfill Legislation 44
3.4.2 Water Quality and Effluent Legislation 47
3.5 Environmental Policy 48
3.6 Sustainable Development and Sustainability 48
3.6.1 Sustainable Landfilling? 49
3.6.2 Concerns with the Technical Definition of Sustainable Landfilling 51
3.7 Policy versus Legislation 52
3.7.1 Pollution over the Short or Long Term 52
3.7.2 Current requirements and their effect on closure/ aftercare 53
3.7.3 Concerns with the Determination for Aftercare 54
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Chapter Four - Constructed Wetlands
4.1 Introduction to Constructed Wetlands 56
4.1.1 Advantages and Disadvantages of CW 57
4.1.2 Efficiency 58
4.2 Types of Constructed Wetlands 58
4.2.1 Free Water Surface (FWS) Constructed Wetlands 59
4.2.2 Vegetative Submerged Bed (VSB) constructed wetlands 59
4.2.3 The Choice of Constructed Wetland Types 60
4.3 CW Hydrology and Hydrological Design Characteristics 61
4.3.1 Hydrological Balance 61
4.3.2 Hydraulic Residence (or Retention) Time (HRT) 62
4.3.3 Precipitation and Evapotranspiration Impacts 64
4.3.4 Water Level Estimation (Flow modeling) 65
4.4 Constructed Wetland Design Parameters 67
4.4.1 Sizing of the VSB Using Pollutant Loading Criteria 68
4.4.2 VSB Bedding Media and Layout 69
4.4.3 Vegetation 71
4.4.4 The Biotic Element In and Around CW 73
4.4.5 Environmental Consideration in Design 74
4.5 Pollution Removal Mechanism in Subsurface CW 75
4.5.1 Organic Matter 76
4.5.2 Nitrogen 76
4.5.3 Other Pollutants 78
4.5.4 Debate over the Oxygen in System 80
4.6 Constructed Wetlands as Appropriate Leachate Treatment 80
4.6.1 Affordability 81
4.6.2 Operability 82
4.6.3 Reliability 83
4.6.4 Appropriate Treatment in the South African Context 83
Chapter Five - Study Site and Experimental Procedures
5.1 Study Site 85
5.1.1 Bisasar Road Landfill 85
5.1.2 Initial Biological Treatment Research 87
5.2 Summary of Design 89
5.2.1 Planted Macrophyte Vegetation 93
5.2.2 Modifications from the Initial Experimental Study 94
5.2.3 Local climatic conditions and modeling 94
5.3 Operations 96
5.4 Sampling 96
5.5 Testing 97
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Chapter Six - Results of the VSB Treatability Trials
6.1 Presentation of the Data 98
6.2 Hydraulic Balance 98
6.3 Characteristics of the Influent 100
6.4 Influent and Effluent Concentrations 101
6.4.1 Ammonia 101
6.4.2 Nitrate/Nitrite 102
6.4.3 COD 103
6.4.4 BOO 103
6.5 Mass of Influent and Effluent 104
6.5.1 Ammonia 104
6.5.2 Nitrate and Nitrite 105
6.5.3 COD 105
6.5.4 BOO 106
6.6 Ratio of BOO to COD 107
6.7 Removal Efficiencies 108
6.7.1 Ammonia 108
6.7.2 Nitrate/Nitrite 109
6.7.3 COD 110
6.7.4 BOO 111
6.8 Changes in Other Constituents 112
6.9 Notable Qualitative Observations 112
6.10 Summary of the Results 114
6.11 Maintenance of the VSB 114
Chapter Seven - Conclusions
7.1 Overall Conclusions 116
7.2 Study Limitations 116
7.3 Treatment performance 117
7.3.1 Nitrogen 117
7.3.2 Organics 118
7.4 Full-scale Recommendations 118
7.5 Future Research 119
References 121
Appendix A 134
Appendix B 137
Appendix C 138
Appendix 0 140
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LIST OF TABLES
2.3.1 General characteristics of acetogenic and methanogenic leachates. 15
2.5.1 Chemical composition of MSW landfill leachates 19
Discharge limit values applicable to discharge of wastewater into a water
3.4.1
resource 37
A comparison between the focus of short-term and long-term environmental
3.7.1
concerns. 54
4.4.3 Environmental conditions for the survival of specific macrophytes 70
4.4.4 Characteristics of Animals Found in Constructed Wetlands 74
Analytical techniques used to measure the amount of aggregate organic
4.5.1
matter in waste water 77
Comparison of three methanogenic leachates from municipal solid waste
5.1.1
landfill sites 86
Design summary and overall layout of the Vegetative Submerged Bed
5.2.1
(VSB) Constructed Wetland (CW) 90
A comparison of the previously treated leachate used in the 2001 study
5.2.2
(Olufsen 2003) and the raw methanogenic leach ate used in this 2003 study 94
Total average monthly precipitation and predicted evapotranspiration values
5.2.3
for the Durban area 95
Listing of the dates within each batch of leach ate and a comparison
6.1.1
between actual date and day in the trial. 98
6.3.1 Concentration of the VSB CW influent 100
6.8.1 Concentrations of the influent, at sampling pipe #1 and the effluent 112
Areas excluded from General Authorization for discharges to water
A1
resources 134
A2 Listed Water Resources 134
B1 Class-A-Pan Data 137
C1 Durban, South Africa rainfall data during the treatability trials 138
C2 Phragmites australis evapotranspiration data 138
Results of the analysis of the chemical concentrations in the influent. The
01
breaks in the data represent a new batch of leachate 140
02 Results of the analysis of the chemical concentrations in the effluent 141