A laboratory simulation of municipal solid waste biodegradation in landfill bioreactors

Xuan Hoang Nguyen

Dissertation

BEITRÄGE ZU ABFALLWIRTSCHAFT / ALTLASTEN · BAND 85

A Laboratory Simulation of Municipal
Solid Waste Biodegradation in Landfill
Bioreactors



Beiträge zu Abfallwirtschaft/Altlasten
Schriftenreihe des Institutes für Abfallwirtschaft und Altlasten
Technische Universität Dresden
__________________________________________________

Band 85

Dissertation
A Laboratory Simulation of Municipal
Solid Waste Biodegradation in Landfill
Bioreactors


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Dissertation
A Laboratory Simulation of Municipal
Solid Waste Biodegradation in Landfill
Bioreactors
Xuan Hoang Nguyen

Herausgeber
Prof. Dr.-Ing. habil. Dr. h. c. B. Bilitewski
Prof. Dr. rer. nat. Dr. h. c. P. Werner
Beiträge zu Abfallwirtschaft/Altlasten
Schriftenreihe des Institutes für

Abfallwirtschaft und Altlasten
Technische Universität Dresden
Band 85
ISBN: 978-3-934253-78-0
2011
1. Auflage


„A

Laboratory Simulation of Municipal
Solid Waste Biodegradation in Landfill
Bioreactors“

genehmigte Dissertation
zur Erlangung des akademischen Grades
Doktor der Ingenieurwissenschaften
Dr.- Ing.
vorgelegt
an der Fakultät für Forst-, Geo- und Hydrowissenschaften
der Technischen Universität Dresden

MSc. Xuan Hoang Nguyen

Promotionskommission:
Vorsitzender:

Prof. Dr. P. Krebs (Technische Universität Dresden)

Gutachter / Prüfer:

Gutachter:
Prüfer:

Prof. Dr. B. Bilitewski (Technische Universität Dresden)
Assoc. Prof. Dr. C. H. Nguyen (Cantho University, Vietnam)
Prof. Dr. C. Dornack (Brandenburgische Technische
Universität Cottbus)

Tag der mündlichen Prüfung und Verteidigung:

19. September 2011


Preface

Mr. MSc. Nguyen Xuan Hoang has written his thesis about the biodegradation of co-disposed
waste funded with a scholarship by the World Bank. He is teaching in the University of Can
Tho in the Mekong Delta of Vietnam.
MSc. Nguyen Xuan Hoang took up a very important subject for Vietnam, but also for the
surrounding countries with a similar climate and state of waste management. The waste
management of Vietnam is despite of advanced laws and regulations in an early stage.
Landfill and dumping is the predominant waste disposal option without considering the longterm implication for the environmental and the drinking water resource.
He used electroplating sludge disposed together with household waste to determine the
emission of heavy metal.
MSc. Nguyen Xuan Hoang did en excellent work in Dresden. He was able to establish a
complex and time demanding research on landfill bodies with Vietnamese waste.
He succeeded to find important results for the international landfill research. I wish this
dissertation a number of interested readers.
Dresden September 2011

Prof. Dr.-Ing. habil. Dr. h.c. Bernd Bilitewski



Acknowledgements

Acknowledgements

The work presented in this doctoral dissertation was conducted at the Institute of Waste
Management and Contaminated Site Treatment (IAA) at Technische Universität Dresden
(TUD) from October 2008 to May 2011. This PhD study was financially supported by
scholarship grants from the Training and Research Innovation Grant (TRIG) project
(World Bank). All experimental implementation was funded by the IAA and the FORUM
für Abfallwirtschaft und Altlasten e. V.
I do realize that this dissertation could not have been completely finished without the full
support from the people around me. Therefore, I would like to express my thanks to those
who made this dissertation possible.
First of all, I would like to express my special gratitude to my supervisor, Prof. Dr.-Ing.
habil. Dr.h.c. Bernd Bilitewski, for his supervision, advice, guidance during the time I
worked at IAA, as well as giving me the chance to carry out such an interesting topic of
research. He has not only provided funds for research but also provided me valuable
scientific support and encouragement. He showed me the way to think in right direction
and the way to approach scientific problems in Germany and Europe. Without this valuable
support from him, it would have been extremely difficult to make this work possible.
I am deeply impressed my sincere gratitude and thanks to Dr. Alexander Janz who worked
as my co-supervisor since very beginning of the experimental establishment. He has not
only contributed his expertise on lysimeters but also took time for guidance and discussion
on all problems that occurred during my experimental operation. I am also thanking him
for sparing his valuable time and going through my work with useful discussions and
valuable suggestions together with a sense of humor, enthusiasm and a gracious behavior

as well.
Also, I would like to express my sincere thank towards Dr. Stephan Mattesteig who helped
me a lot in the discussion and testing of biogas measurement. Besides that, he was also
guiding me for a site establishment and measurements of the biogas in composting sites.
My sincere appreciation goes to Dr. Catalin Stefan for taking his valuable time to review
on my work and helping me improve the structure, the grammatical translation of the
dissertation.

i


Acknowledgements
I want to express my sincere thank to Dr. Christoph Wünsch who has kindly contributed in
many administrative issues, especially in the German version of the abstract and main
conclusions. My deep thanks go to Dr. Daniel Schingnitz who has been helping me a lot
since last year especially in the communication with the German speaking technical staff.
I would like to thank to Mrs. Dagmar Gerbet, Mr. Martin Katzschner, and Mrs. Jacqueline
Rohde who analyzed my samples during the experiments. I would also thank to Mr. Gerd
Schmieder who took time to do all technical assistant for testing of the lysimeters as well
as in the process of freeze sampling. I also express my sincere thanks to all my colleagues
in the IAA for their encouragement and kind assistance throughout the work. The warm
support of all my friends enabled me to complete this thesis and have a wonderful time
along the way.
I want to send my thanks and best regards to all my colleagues in the Department of
Environmental Engineering, College of Environment and Natural Resources for their
sharing and undertaking my assignments at Cantho University. My special thanks to Mr.
Le Hoang Viet who is the Head of Department and Vice Dean of College for his
encouragements and supports.
My deepest gratitude goes to my family, to my parents and all my brothers and sister, who
always supported and encouraged me so much in my life from Vietnam. With love,

kindness and care, they have always been supportive for me pursuing my study and
dreams.
At last but not least, I would like to thank my beloved family, my wife Phuong Y. Lam and
our joyful daughter Quynh L.V. Nguyen and son Khang H. Nguyen, who are powerful
source of inspiration and energy for my life. They always bring a smile on my face and a
peace in my heart. To them, this work is dedicated.
Xuan Hoang Nguyen

ii


Abstract
Abstract
The landfills in Vietnam consist predominantly of open dumpsites and only a few
engineered landfills. The unsorted municipal solid waste (MSW) disposed includes
domestic, industrial, treatment sludge, healthcare and even mixed hazardous or nonhazardous wastes. Some of these sources can provide a high potential in heavy metals
(HMs) leaching which has not been fully defined and studied yet.
Lysimeter testing has been carried out for high organic MSW with/without electroplating
sludge (ES) containing HMs in order to study the anaerobic biodegradability and its
potential emissions, the HMs release and its long-term leaching behaviour, and the
inhibitory factors. For that reason, many physical - chemical parameters were measured in
addition to HMs (copper, nickel, zinc, iron, manganese, lead, chromium and cadmium)
contents from the input, transformable, and output materials.
Anaerobic degradation of high organic MSW was found strongly inhibited under low pH
environment and in the presence of high organic acids. The pH value was stable in the
range of 4.4 – 5.2 for more than one year (68 weeks). The organic acids were present in
high range (6,067 – 14,363 mg/l) until the 28th week and have significantly inhibited the
entire anaerobic system for both methanogenic and acidogenic microbes’ activities leading
to a low methane production and biogas yield.
Micro-aeration has been applied as an effective method to rescue the living of anaerobic

microorganisms. COD, organic acids, pH, and to a high extend the sulphates were
definitely affected by micro-aeration. However, interval operation between micro-aeration
phases should be long enough for the reclamation of microbes in their acclimation.
As a result, the biogas yield obtained was about 29-52 l/kg DM, in which the methane
content was about 2.3 – 5.4 l/kg DM. HMs were found to be slightly affected by microaeration especially Mn, Fe, and Cr whose concentration was increasing during the short
micro-aeration phase (1 week) and decreasing in end-phase aeration (1 month).
All HMs contained in the leachate were present in much lower concentrations than the
inhibitory levels published in the literatures. The inhibition/decay noted in the lysimeters
containing ES can be hypothetical explained by the total concentration of HMs. The
release of HMs was significantly delayed and therefore it presents a long-term leaching
potential of these harmful substances.
It is needed more scientific research regarding real landfill waste in Vietnam in lab. scale
lysimeters and also real test as well as more study in the leaching of HMs in the later
phases or aeration.

iii


Zusammenfassung
Zusammenfassung
In vietnamesischen Deponien, die in erster Linie aus offenen Ablagerungen und teilweise
aus geordneten Deponien bestehen, wurden unbehandelte Abfälle, hautsächlich
Siedlungsabfällen, Industrieabfälle, Aufbereitungsschlämme, Krankenhausabfälle und
sogar Sonderabfälle abgelagert. Einige Abfallfraktionen können hohe Potenziale an
Schwermetallen enthalten, die über das Sickerwasser ausgetragen werden. Die Mengen
und Konzentrationen der Schwermetalle in Deponiesickerwässern vietnamesischer
Deponien ist bislang nicht definiert und ermittelt wurden.
Lysimetertests wurden mit Restabfällen aus organischen Material, gemeinsam mit und
ohne schwermetallbelasteten Galvanisierschlämmen durchgeführt, um den anaeroben
Bioabbau und die einhergehenden Emissionen, das Langzeitverhalten der

Schwermetallfreisetzung und die Inhibitationsfaktoren zu ermitteln. Aus diesem Grund
wurden unterschiedliche physikalisch-chemische Parameter sowie die Schwermetallgehalte
(Kupfer, Nickel, Zink, Eisen, Magnesium, Blei, Chrom und Kadmium) des
Eingangsmaterials, der Zwischenprodukte und des Ausgangsmaterials gemessen und
analysiert.
Der anaerobe Abbau der hoch organischen Abfallfraktion wird stark durch niedrige pHWerte und organische Säuren gehemmt. Der pH-Wert ist über mehr als einem Jahr (68
weeks) im Bereich zwischen 4,4 und 5,2 stabil geblieben. Die Konzentration der
organischen Säuren lagen im Bereich zwischen 6.067 und 14.363 mg/l, bis in der 28ten
Woche das gesamte anaerobe System erheblich gehemmt wurde und sowohl die
methanogenen als auch die acetogenen mikrobiellen Aktivitäten zurückgingen. Dies führte
im Ergebnis zu einer verminderten Methanproduktion und Biogasausbeute.
Als effektive Methode zur Rettung der anaeroben Mikroorganismen erwies sich die
Mikrobelüftung des Systems. Es stellte sich heraus, dass die Mikrobelüftung Einfluss auf
den CSB, die organische Säuren, den pH-Wert und speziell auf die Sulphate hat. Die
Interwalle zwischen den Phasen der Mikrobelüftungen sollte jedoch lang genug sein um
die Reaktivierung der Mikroorganismen und deren Akklimatisierung zu gewährleisten.
Als Ergebnis lässt sich eine Biogasausbeute von 29 bis 52 l/kg TS, mit einem Metangehalt
von 2,3 bis 5,4 l/kg TS erzielen. Die Schwermetallfreisetzung wird durch die
Mikrobelüftung leicht beeinflusst. Speziell bei Mn, Fe und Chrom stieg diese während der
kurzen Mikrobelüftung (eine Woche) an und ging während der Endbelüftung (ein Monat)
zurück.
Die Schwermetallgehalte im Sickerwasser waren deutlich geringer als die in der Literatur
angegebenen Niveaus der Inhibitierung. Die Inhibitierung/der Abbau in den mit
Galvanisierschlamm beaufschlagten Lysimetern kann hypotetisch mit der Konzentration an
Schwermetallen erklärt werden. Die Freisetzung der Schwermetalle erfolgt deutlich
verspätet, was zu einem Langzeitauslaugpotenzial dieser gesundheitsschädlichen
Substanzen führt.
Die Ergebnisse zeigen, dass weitere wissenschaftliche Forschungen im Bereich
Deponierung von vietnamesischen Abfällen in Lysimetern im Labormaßstab, als auch
direkt in Deponien durchgeführt werden sollten. Des Weiteren sind Untersuchungen zu

Auslaugprozessen von Schwermetallen in den späteren Phasen der Belüftung zu
realisieren.
iv


Table of contents
Table of contents
Acknowledgements ............................................................................................................... i
Abstract ...............................................................................................................................iii
Zusammenfassung .............................................................................................................. iv
List of tables ......................................................................................................................viii
Lists of figures..................................................................................................................... ix
List of abbreviations........................................................................................................... xi
1

2

INTRODUCTION ....................................................................................................... 1
1.1

Background............................................................................................................ 1

1.2

State of the art of landfill research with lysimeters ............................................... 3

1.3

Objectives of the research...................................................................................... 4

1.4

Outline of the dissertation ..................................................................................... 4

LITERATURE REVIEW ........................................................................................... 7
2.1

Municipal solid waste definition and characteristics............................................. 7

2.1.1

MSW definition ............................................................................................. 7

2.1.2

Waste generation and composition in developing countries ......................... 7

2.1.3

Landfilling ..................................................................................................... 9

2.2

Biodegradation processes of MSW ..................................................................... 11

2.2.1

Aerobic process ........................................................................................... 11

2.2.2

Anaerobic fermentation process .................................................................. 12

2.3

Landfill operation process ................................................................................... 13

2.3.1

Landfill types............................................................................................... 13

2.3.2

Biochemical process in landfills.................................................................. 14

2.3.3

Water balance .............................................................................................. 19

2.4

Problems associated with landfill ........................................................................ 19

2.4.1

Leachate....................................................................................................... 20

2.4.2

Landfill gas .................................................................................................. 21

2.4.3

Environmental factors affecting the biodegradable process........................ 22

2.5

Landfill simulation reactor development............................................................. 25

v


Table of contents
3

MATERIALS AND METHODS.............................................................................. 27
3.1

Introduction ......................................................................................................... 27

3.2

Material preparation ............................................................................................ 27

3.2.1

Municipal solid waste.................................................................................. 27

3.2.2

Hazardous waste components...................................................................... 29

3.3

Experimental setup .............................................................................................. 29

3.3.1

Reactor design ............................................................................................. 29

3.3.2

Experimental process design and operation ................................................ 31

3.4

3.4.1

Leachate and gas sampling .......................................................................... 32

3.4.2

Analytical methods ...................................................................................... 33

3.5

4

Sampling and analytical methods ........................................................................ 32

Basic parameter calculations ............................................................................... 35

3.5.1

Total solids and volatile solids .................................................................... 35

3.5.2

Organic matter removal efficiency .............................................................. 35

3.5.3

Development of acceleration factor............................................................. 36

3.5.4

Carbon mass balance ................................................................................... 37

DECOMPOSITION OF HIGH ORGANIC MUNICIPAL SOLID WASTE

LANDFILL ........................................................................................................................ 39
4.1
4.1.1

Leachate emission and quality..................................................................... 39

4.1.2

Biogas production........................................................................................ 52

4.2

Micro-aeration – an effective method to reduce inhibition ................................. 55

4.2.1

Effects of micro-aeration on the biodegradability....................................... 55

4.2.2

Aeration effect on biogas production .......................................................... 62

4.3
5

Anaerobic decomposition of high organic MSW ................................................ 39

Concluding remarks............................................................................................. 65

LEACHING OF HEAVY METALS IN HIGH ORGANIC MUNICIPAL SOLID

WASTE LANDFILL ......................................................................................................... 67
5.1

Introduction ......................................................................................................... 67

5.2

Influence of HMs on the anaerobic biodegradability .......................................... 68

5.2.1

Influence of HMs on leachate quality ......................................................... 68

5.2.2

Effect of HMs on biogas production ........................................................... 73
vi


Table of contents
5.3

6

Leaching of HMs from high municipal solid waste landfill................................ 76

5.3.1

Leaching of HMs in anaerobic biodegradability ......................................... 76

5.3.2

Mass balance of HMs .................................................................................. 82

5.3.3

Leaching of heavy metals with micro-aeration effect ................................. 84

5.4

Heavy metals distribution in deep waste horizon................................................ 88

5.5

Concluding remarks............................................................................................. 92

PREDICTION OF LONG TERM EMISSIONS OF ANAEROBIC MUNICIPAL

SOLID WASTE IN LANDFILL SIMULATION REACTOR...................................... 95

7

6.1

Introduction ......................................................................................................... 95

6.2

Carbon mass balance ........................................................................................... 95

6.3

Long term emissions of MSW............................................................................. 98

6.3.1

Liquid-solid ratio and acceleration coefficient............................................ 98

6.3.2

Long-term prediction based hydraulic coefficient relation ......................... 99

6.4

Acid buffering capacity and long-term leaching behavior of HMs................... 102

6.5

Concluding remarks........................................................................................... 104

CONCLUSIONS AND OUTLOOK ...................................................................... 105
7.1

Conclusions ....................................................................................................... 105

7.2

OUTLOOK........................................................................................................ 108

References ........................................................................................................................ 111
List of Annexes

vii


List of tables
List of tables
Table 2-1 MSW generation rate of major Asian cities.......................................................... 8
Table 2-2 Composition of MSW in Asia cities ..................................................................... 9

Table 2-3 Types and classification of landfill in Germany and in Asian countries ........... 14
Table 2-4 Typical parameters analyzed from leachate in municipal landfill ...................... 20
Table 2-5 Typical landfill gas composition......................................................................... 22
Table 2-6 Factors influence the efficiency of degradation in a landfill system .................. 23
Table 2-7 Effects of free ammonia on anaerobic processes ................................................ 24
Table 3-1 Composition of experimental MSW ................................................................... 28
Table 3-2 Characteristics of HMs of the input of MSW and of electroplating sludge........ 29
Table 3-3 Experimental formulas used in the experiments ................................................. 31
Table 4-1 Micro-aeration and end-phase aeration in the experiment.................................. 55
Table 4-2 Aeration effect on BOD, COD, organic acids and SO42- in LSR1 and LSR2..... 59
Table 4-3 Production and yield of biogas and methane ...................................................... 65
Table 5-1 Total amount of HMs in input electroplating sludge and in LSRs ..................... 67
Table 5-2 Cumulative COD and organic acids during observed period in LSRs................ 70
Table 5-3 Production rate and yield of biogas and methane in LSR3 and LSR4................ 75
Table 5-4 HMs content in input materials in comparison to criteria................................... 77
Table 5-5 Comparison of HMs leaching to the typical range and upper limit .................... 81
Table 5-6 Total discharge of HMs in lysimeters with ES added......................................... 83
Table 5-7 Micro-aeration and end-phase aeration application in LSR3 and LSR4............. 85
Table 5-8 Discharge rate of HMs by micro-aeration/end-phase aeration (%) .................... 87
Table 5-9 Concentration of HMs remaining in residues ..................................................... 91
Table 6-1 L/S ratio in all experiment .................................................................................. 99
Table 6-2 ANC4.0 of the samples and time until leaching ............................................... 103

viii


List of figures
Lists of figures
Figure 2-1 Predominant landfilling figures in European countries ..................................... 10
Figure 2-2 MSW treatment percentage in some developing countries ............................... 11

Figure 2-3 Three phases of anaerobic processing of organic matters ................................. 13
Figure 2-4 Detail of the major stages of waste degradation in landfills.............................. 16
Figure 2-5 Changing of leachate and gas in a landfill......................................................... 17
Figure 3-1 MSW composition in Ho Chi Minh city............................................................ 28
Figure 3-2 Sketch of landfill simulation reactor (LSR)....................................................... 30
Figure 3-3 Design of experimental LSR system ................................................................. 32
Figure 4-1 Distribution of pH and temperature in LSR1 and LSR2 .................................. 40
Figure 4-2 Redox potential in LSR1 and LSR 2 ................................................................. 41
Figure 4-3 Concentrations of COD, BOD5 in the leachate of LSR1 and LSR2.................. 43
Figure 4-4 Distribution of BOD/COD ratio in the leachate of LSR1 and LSR2 ................ 45
Figure 4-5 Organic acids in the leachate of LSR1 and LSR2 ............................................. 46
Figure 4-6 TKN and NH4 emissions in the leachate during experiment ............................. 49
Figure 4-7 NH4_N/COD ratio in LSR1 and LSR2 .............................................................. 50
Figure 4-8 Sulphate and COD/SO42- ratio in the LSR1 and LSR2...................................... 52
Figure 4-9 Landfill gas production in LSR1 and LSR2 ...................................................... 53
Figure 4-10 Biogas production in LSR1 and LSR2 ............................................................ 54
Figure 4-11 pH and temperature in LSR1 and LSR2 .......................................................... 56
Figure 4-12 Redox potential in LSR1 and LSR2 during experimental period.................... 58
Figure 4-13 Emissions of BOD5 and COD in LSR1 and LSR2 by micro-aeration............. 59
Figure 4-14 Organic acids emission in LSR1 and LSR2 by aeration.................................. 60
Figure 4-15 Aeration effect on sulphate in LSR1 and LSR2 .............................................. 61
Figure 4-16 Aeration effect on biogas production in LSR1 ................................................ 62
Figure 4-17 Aeration effect on biogas production in LSR2 ................................................ 62
Figure 4-18 Biogas yield in LSR1 and LSR2...................................................................... 63
Figure 5-1 pH, COD and organic acid changes during experimental period ...................... 68
Figure 5-2 Sulphate reduction in LSR3 and LSR4.............................................................. 72
Figure 5-3 Biogas production in LSR3 ............................................................................... 74
Figure 5-4 Biogas production in LSR4 ............................................................................... 74
Figure 5-5 Biogas yields in LSR3 and LSR4 ...................................................................... 76
Figure 5-6 HMs release in LSR1 and LSR2........................................................................ 78

Figure 5-7 HMs leaching in LSR3 ...................................................................................... 79
ix


List of figures
Figure 5-8 HMs leaching in LSR4 ...................................................................................... 80
Figure 5-9 HMs balance in LSR1 and LSR2 without ES.................................................... 83
Figure 5-10 HMs balance in LSR3 and LSR4 with ES....................................................... 84
Figure 5-11 Comparison of HMs discharge in LSR3 and LSR4......................................... 86
Figure 5-12 Distribution of HMs in LSR3 by deep waste horizon ..................................... 88
Figure 5-13 Distribution of HMs in LSR4 by deep horizon ............................................... 90
Figure 5-14 Adsorption of HMs on the residues in LSR3 and LSR4. ................................ 92
Figure 6-1 Cumulative TOC discharge via leachate and biogas ......................................... 96
Figure 6-2 The organic carbon components in experiment................................................. 96
Figure 6-3 Carbon balance in LSRs .................................................................................... 98
Figure 6-4 Long-term emission of COD, TKN and TOC in lysimeter without sludge..... 101
Figure 6-5 Long-term emission of COD, TKN and TOC in lysimeter with 6% sludge ... 101
Figure 6-6 Long-term emission of COD, TKN and TOC in lysimeter with 12% sludge . 102

x


List of abbreviations
List of abbreviations

AOX

adsorbable organic halogens

ANC

acid neutralization capacity

BMBF

German Federal Ministry of Education and Research

DM

dry matter

FA

free ammonia

FRG

The Federal Republic of Germany

GDR

The German Democratic Republic

L/S

liquid – solid ratio

LSRs

landfill simulation reactors (lysimeters)

MONRE

Vietnamese Ministry of Natural Resources and Environment

MPB

methane-production bacteria

MSW

municipal solid waste

ODA

Official Development Assistance

OFMSW

organic fraction of municipal solid waste

OM

organic matter

QCVN

Vietnam National Technical Regulation

RP

redox potential

SPT

Standard Pressure and Temperature

SRB

sulphate-reducing bacteria

SWM

solid waste management

TN

total nitrogen

TOC

total organic carbon

TVS

total volatile solid

URENCOs

Urban Environment Companies

xi


xii


1. Introduction

1

1.1

INTRODUCTION

Background

Solid waste management (SWM) is an integral part of the urban environment and planning
meant to ensure a safe and healthy human environment. Rapid economic growth caused by
industrialization of the developing Asian countries such as Vietnam has created serious
problems of waste disposal due to uncontrolled and unmonitored urbanization (ISWA &

UNEP, 2002). The problem is further aggravated by the lack of financial as well as human
resources trained in SWM practices in the sphere of collection, transportation, processing
and final disposal. The waste generated in the developing countries is seemed to be similar
in composition, the variation between regions being dictated by the climatic, cultural, and
industrial, infrastructural and legal factors (AIT, 2004).
Vietnam produces over 15 millions tons solid waste each year from various sources. There
are more than 80 percent (12.8 millions tons/yr) from municipal sources, including
households, restaurants, markets, and businesses. Like other developing countries in

Southeast and South Asia, opened and controlled dumps are the predominant form of waste
disposal in Vietnam. Almost all the municipal solid waste (MSW) is disposed of into
landfills, which can be considered as a sole treatment method for MSW in the last decades
(MONRE, 2004)
Among 91 large landfills in the whole country, there are only 17 sanitary landfills, mostly
funded under Official Development Assistance (ODA) programs (MONRE, 2004). Most
hazardous healthcare and industrial waste is mixed with municipal waste at collection
sources with total amount of about 160,000 tons, of which 130,000 tons came from
industrial sources and 64% of them came from the South of Vietnam. The remainder was
generated by the healthcare sector (21,000 tons/yr) and agriculture (8,600 tons/yr). Few
data are available regarding collection and disposal practices at healthcare and industrial
facilities. Industrial waste in Vietnam amounts approximately 25% of MSW but varies
depending on province/region and its degree of industrialization (MONRE, 2004).
Waste handling in Vietnam is mainly carried out by the Urban Environment Companies
(URENCOs), which are responsible for the collection and disposal of municipal waste,
including domestic, institutional, and in most cases industrial and healthcare waste.
Although in theory the industries and hospitals should be responsible for their waste - and
1


1. Introduction
the government’s role should be developing, implementing, and enforcing regulations such arrangements are not yet in place in Vietnam (MONRE, 2004).
A recent inventory of hazardous waste in the country indicated that the main industrial
sectors generating hazardous wastes are electrical mechanics, food processing, chemicals,
mechanical, and metallurgy. The large portion of hazardous waste was found in
mechanical industries (47.4%), electric – electronic industries (76.8%), chemical industries
(69.3%), and textile, leather and dying industries (46.5%) (Nguyen, 2009). These sources
of hazard are potentially increasing the concentration of heavy metals (HMs) in landfill
bodies, which can strongly affect the surface and ground water resources around the
landfill. However, it seems to be no sufficient studies on landfill operation process as well

as the effect of HMs emissions from landfill.
Moreover, the concept of landfill simulation reactors (lysimeters), which is specially
applied to study the biodegradation process inside the landfill’s body, seems to be new for
the waste management in Vietnam. Thus, the present research project “A laboratory
simulation of municipal solid waste biodegradation in bioreactor landfill” for Vietnam
MSW was reasonably carried out.
This entire project study is carried out within two years in the laboratory of the Institute of
Waste Management and Contaminated Site Treatment in Pirna, Germany. The
investigations included anaerobic decomposition of MSW and the influence of HMs on the
anaerobic degradation and their long term leaching. In the study, input MSW was collected
in Dresden and prepared to reproduce exactly the waste composition in Vietnam. This can
be regarded as representative of the typical waste in landfill site in Vietnam. The hazardous
waste source is electroplating sludge (ES), which was collected from the electroplating
industry “Nehlsen-Plump Ost GmbH Industrie- und Gewerbegebiet” in Dresden.
As a result, this research tends to answer some typical questions:
1. Which long-term contaminants can be expected from the landfill sites in Vietnam?
2. Which quantities of leaching pollutants are expected from disposal sites with codisposal of hazardous industrial waste (ES)?
3. What are the effects of different meteorological boundary conditions and
characteristics of landfill (precipitation, high ground water, high organic waste, height
of landfill, etc,) on the emissions?

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1. Introduction

1.2

State of the art of landfill research with lysimeters

The modern landfill research in Germany started with research programs during 1976 1991 funded by German Science Foundation. In this research, the landfill body was
considered as a black box in which the input – output streams were possibly measured and
evaluated. The landfill body itself was not fully understood even the outdoor lysimeters
were used and run over more than 20 years. The prognosis of the behaviour of the landfill
body over time was only limited. The results of this research nevertheless represented the
basis of construction regulations for landfills in Germany and Europe.
From 1993 to 1996, the joint research project “Landfill body” funded by the German
Ministry of Education and Research (BMBF) and carried out by four German technical
universities (Wuppertal, Aachen, Hamburg-Harburg and Dresden). The emphasis of the
investigations lay on the description of the behaviour of old waste landfill, its present
hazardous potential and long-term behaviour by accelerating the process via lysimeter
control. The waste composition and the practice of waste disposal in the former GDR was
to be described, as well as the resulting influence on the properties of the deposited waste,
the concentration of pollutants, the leaching results, the production of biogas, and the longterm emission potential in comparison with landfills in the old FRG. The basic requisite
was conformity with the laboratory stabilization test that was proven with the process in
the waste body of real landfills (Andreas and Bilitewski, 1999).
From 2000 to 2005, the two projects “The technology of low-pressure ventilation for insite stabilization of landfills and old deposits “and the “Aerobe in situ stabilization of old
landfills in Saxony reducing the time and costs for aftercare“ funded by the Saxony
Regional Authority for Environment and Geology (LfUG Sachsen), landfills were aerated
to finalize the stabilization process of an old landfill and stop leachate and gas emission
(Hantsch, Michalzik and Bilitewski, 2002). As result, lysimeters were developed with
aeration system.
The method of enhanced air supply (so-called aeration) of landfill waste by means of air
injection wells accelerates the biological decomposition of biodegradable organic
compounds. Thus, organic emissions can be significantly reduced and characterized by a
decreasing content of organic carbon (such as TOC, DOC, COD), and nitrogen compounds
(NH4-N) (Heyer and Stegmann, 1997). The advantages of an in-situ stabilization of the
landfill body involved a significant reduction of the after-care period, monitoring and
decontamination costs, less cost-intensive surface sealing with regard to reduce the landfill
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1. Introduction
emissions (Cossu et al., 2001; Ritzkowski et al., 2001). This project was developed the
prescription of rules how to realize landfills from the aftercare to the later phase of reuse.
Up to now, there has been no research on the behaviour of the landfill body done in
Vietnam. Most of the landfill studies were based on the investigation of landfill leachate
and gas on site. The landfill of Go Cat and Phuoc Hiep in Hochiminh city can be stated as
first landfills with a proper catchment system for the leachate and gas collection. The
leachate generation rate is about 800-1,000 m3/day and landfill gas generation rate is
approximately 500,000-700,000 m3/day in the landfills Go Cat and Phuoc Hiep in
Hochiminh city where MSW has not been separated at source (see annex A1) (Dan and
Viet, 2009).

1.3

Objectives of the research

The study focuses on the physical, chemical and biological processes occurring inside the
lysimeters as well as in the landfill body in reality. The inherent inhibitory factors such as
pH, organic acids, TKN and SO42- were studied, as well as the effect of HMs from ES on
the degradability of MSW landfill. The specific objectives are focused on:
-

To investigate the anaerobic degradability of high organic MSW via leachate and
biogas pathway.

-

To study the anaerobic degradability of co-disposal landfill of MSW and industrial

sludge containing HMs.

-

To study the influence of micro-aeration on the anaerobic degradability as an
enhancement method in declining of inhibition.

-

To estimate the leaching of HMs and its long-term behaviour in bio-degradability of
high organic MSW.

1.4

Outline of the dissertation

The dissertation comprises seven sections. Section 1 provides the introduction on the state
of the art of landfill research, objective of the dissertation and its outline. Section 2
presents the literature – state of knowledge of the study whereby anaerobic biodegradation
processes in landfill as well as the environmental factor affecting to the biodegradability.
The materials and methods are described in details in section 3. The main results of the
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1. Introduction
studies have been conduced and described in section 4, 5 and 6. Section 4 discusses about
the decomposition of high organic MSW landfill whereby the result of anaerobic processes
as well as the effect of micro-aeration has been carried out. Section 5 describes the
leaching of HMs in high organic MSW landfill via leachate. The prediction of long-term
emissions of anaerobic MSW in landfill simulation reactor has been estimated and

described in section 6. In there, the carbon mass balance and long-term emissions of MSW
based on the acceleration factor and long-term leaching behaviour of HMs with ANC are
taken into consideration. Section 7, the last section, summarizes the emphatic conclusions
resulted from the research.

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