COMPARATIVE STUDY OF EFFLUENT FROM ANAEROBIC DIGESTERS FOR HUMAN AND

94 Pages·2012·1.25 MB·English

COMPARATIVE STUDY OF EFFLUENT FROM ANAEROBIC DIGESTERS FOR
HUMAN AND FRUIT WASTE

by
Abdul-Aziz Issah (B.Sc. Agriculture Technology)

A thesis submitted to the Department of Agricultural Engineering
Kwame Nkrumah University of Science and Technology
in partial fulfillment of the requirements for the degree
of

MASTER OF SCIENCE
IN
AGRO-ENVIRONMENTAL ENGINEERING

College of Engineering

AUGUST, 2011
DELCLARATION
I, Abdul Aziz Issah hereby declare that this submission is my own work for the award
of M.Sc. Agro-Environmental Engineering and that to the best of my knowledge, it
contains no material previously published by another person or group of people or
material that has been accepted for the award of any other degree by the university,
except where due acknowledgement has been made in the text.

Abdul-Aziz Issah (PG3769009) ……………………. 19TH August, 2011
Student Name and ID Signature Date

Certified by:

Dr. Elias .D. Aklaku …………………… 19TH August, 2011
Principal Supervisor Signature Date

Certified by

Prof. Ebenezer Mensah ………………………. 19TH August, 2011
Head of Department Signature Date
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ABSTRACT
The study examined comparatively the levels of macronutrients, pollution monitoring
parameters, metals and pathogenic indicator organisms from effluent of two anaerobic
digesters for human waste and fruit waste with respect to the influent. Both digesters
were operated within mesophilic conditions at very short hydraulic retention time.
Laboratory analysis of these parameters (macronutrients, pollution monitoring
indicators and pathogenic indicator organisms) was therefore important to ensure that
utilisation of the effluent was environmentally friendly and acceptable to farmers, the
food industry, consumers, the environmental protection agency and the World Health
Organisation (WHO). Results of this study found that, pH and macronutrients (NH -
4
N, P O and K O) were higher in the effluent than in the influent for both human and
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fruit waste. For instance, ammonium-N was about 25.1% higher in the effluent with
respect to the influent for human waste and 19.1% higher in the effluent of fruit
waste. Total Solids (TS), Volatile Solids (VS), BOD and COD were lower in the
effluent than in the influent for both wastes (human and fruit wastes). Reduction of
51.6% Total Coliforms (TC), 53.4% Faecal Coliform (FC) and 58.9% E. coli were
found in the digested effluent of fruit waste. 62.8% TC, 64.4% FC and 60.6% E.coli
were found in the digested effluent of the human excreta. Heavy metals in the
respective effluents were within tolerable limits that are acceptable to the Ghana
Environmental Protection Agency (GEPA). The results of this study therefore join
other studies to show that the process of anaerobic digestion causes reduction in
pollution indicators, destruction of pathogenic organisms and increases the
availability of macronutrients.
Keywords: Anaerobic digestion, Influent, Effluent, Macronutrients, Metals,
Pathogens, Pollution indicators.
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ACKNOWLEGEMENT
I am most grateful to the Almighty God for the successful completion of this thesis.
My deepest gratitude to my principal supervisor, Dr. E.D. Aklaku for proposing this
topic and his invaluable support and fatherly care offered me throughout the entire
work.

My profound thanks and appreciation goes to the entire staff of the department of
Agricultural Engineering, KNUST for their encouragement throughout my post
graduate study. I equally thank the staff of Soil Research Institute (SRI) of the
Council for Scientific and Industrial Research (CSIR), Kumasi and the Water
Research Institute (WRI) of CSIR, Tamale for making their laboratories available to
me. To all those who taught me especially Prof. Ato Bart-Plange and Prof. Ebenezer
Mensah, I say may God bless you.

I am also grateful to all friends who in diverse ways supported me throughout my
education. Special thanks to Mr. Salifu Tayari (Bolgatanga Polytechnic), Mr.
Nantomah Kassim (Zamse Senior High School, Bolgatanga), Mr. Inusah Abdul-Majid
(Vodafone Ghana),Mr. Abubakari Mudasiru and Mr. Salifu Abdul-Rahman for their
encouragement and financial support.

Finally, I thank my parents Mr. Ibrahim Issah and Mrs. Nantomah Khadija for taking
the pain in educating me.
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TABLE OF CONTENTS
DELCLARATION................................................................................................... ii
ABSTRACT ............................................................................................................ iii
ACKNOWLEGEMENT......................................................................................... iv
TABLE OF CONTENTS ........................................................................................ v
LIST OF TABLES .................................................................................................. xi
LIST OF FIGURES .............................................................................................. xiii
CHAPTER ONE ...................................................................................................... 1
1. INTRODUCTION ............................................................................................... 1
1.1 Background ......................................................................................................... 1
1.2 Problem Statement ............................................................................................... 4
1.3 Objective(s) ......................................................................................................... 5
1.3.1 General Objective(s) ......................................................................................... 5
1.3.2 Specific objectives ............................................................................................ 6
1.4 Scope and Delimitations ...................................................................................... 6
CHAPTER TWO ..................................................................................................... 7
2. LITERATURE REVIEW .................................................................................... 7
2.1 Introduction ......................................................................................................... 7
2.2 Basic definitions .................................................................................................. 7
2.3 General Description of AD Process ...................................................................... 9
2.3.1 Hydrolysis ...................................................................................................... 10
2.3.2 Acidogenesis................................................................................................... 11
2.3.3 Acetogenesis ................................................................................................... 11
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2.3.4 Methanogenesis .............................................................................................. 11
2.4 Process Control Parameters of AD ..................................................................... 12
2.4.1 Operational parameters/sludge characteristics ................................................. 13
2.4.1.1 Total solids (TS)/dry matter ......................................................................... 13
2.4.1.2 Organic Dry Matter (ODM) ......................................................................... 14
2.4.1.3 Organic Loading Rate (OLR) ....................................................................... 14
2.4.1.4 Hydraulic Retention Time (HRT) ................................................................. 14
2.4.1.5 Agitation/mixing .......................................................................................... 15
2.4.2 Environmental parameters ............................................................................... 15
2.4.2.1 C: N ratio/Nutrients ...................................................................................... 15
2.4.2.2 Temperature range ....................................................................................... 16
2.4.2.3 pH ................................................................................................................ 16
2.4.2.4 Ammonia ..................................................................................................... 17
2.5 Products of Anaerobic Digestion ........................................................................ 17
2.5.1 Biogas ............................................................................................................. 18
2.5.2 Biogas Effluent (Digestate): Macronutrients and pollution indicators .............. 18
2.5.2.1 TN and NH -N ............................................................................................. 20
4
2.5.2.2 Total P O .................................................................................................... 21
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2.5.2.3 pH ................................................................................................................ 21
2.5.2.4 TS or Organic Dry Matter (ODM) ................................................................ 22
2.5.2.5 Biochemical Oxygen Demand (BOD) .......................................................... 22
2.5.2. 6 Chemical Oxygen Demand.......................................................................... 23
2.5.2.7 Electrical Conductivity (EC) ........................................................................ 23
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2.5.2.8 C/N ratio of digestate ................................................................................... 24
2.6 Heavy metals ..................................................................................................... 24
2.7 Pathogenic Indicator Organisms ......................................................................... 25
2.8 Advantages and Disadvantages of AD ............................................................... 28
Advantages .............................................................................................................. 28
Disadvantages ......................................................................................................... 28
CHAPTER THREE ............................................................................................... 29
3. MATERIALS AND METHODS ....................................................................... 29
3.1 Introduction ....................................................................................................... 29
3.2 Study Area ......................................................................................................... 29
3.2.1 Location, size and demography of the study areas ........................................... 30
3.2.2 The Environment: sanitation and waste management ...................................... 30
3.2.3 Vegetation and Climate ................................................................................... 31
3.3 Materials ............................................................................................................ 32
3.4 Methods ............................................................................................................. 33
3.4.1 Digester start up and acclimatization ............................................................... 33
3.4.2. Preparation of sampling containers ................................................................. 34
3.4.3 Sampling procedure and sample pre-treatment prior to analysis ...................... 34
3.5 Analytical Methods ............................................................................................ 35
3.5.1 Analysis of macronutrients .............................................................................. 35
3.5.1.1 Determination of TKN ................................................................................. 35
3.5.1.2 Determination of ammonium nitrogen (NH -N) ........................................... 36
4
3.5.1.3 Determination of total P O .......................................................................... 37
2 5
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3.5.1.4 Determination of orthophosphate (PO -P) .................................................... 37
4
3.5.1.5 Determination of Potassium ......................................................................... 38
3.5.2 Pollution monitoring indicators ....................................................................... 38
3.5.2.1 Total solids .................................................................................................. 39
3.5.2.2 Volatile solids .............................................................................................. 39
3.5.2.3 Chemical Oxygen Demand (COD) ............................................................... 39
3.5.2.4 Biochemical Oxygen Demand (BOD) .......................................................... 40
3.5.2.5 pH ................................................................................................................ 40
3.5.2.6 Conductivity ................................................................................................ 41
3.6 Analytical method of heavy metals (Cd, Cu, Pb and Zn) .................................... 41
3.7 Analytical procedures for sanitary parameters (pathogenic indicator organisms) 42
3.7.1 Determination of TC and E. coli...................................................................... 43
3.7.2 Determination of FC ....................................................................................... 44
3.7.3 Determination of Salmonella species............................................................... 44
3.8 Statistical Analysis............................................................................................. 45
CHAPTER FOUR ................................................................................................. 46
4. RESULTS AND DISCUSSION ......................................................................... 46
4.1 Macronutrients Level in Terms of TN, NH -N, P O , K O ................................. 46
4 2 5 2
4.1.1 TN, NH -N ..................................................................................................... 47
4
4.1.2 Total and Orthophosphate (P O ) .................................................................... 48
2 5
4.1.3 Total K O ....................................................................................................... 49
2
4.2 Pollution Monitoring Indicators ......................................................................... 50
4.2.1 Total Solids (TS)............................................................................................. 51
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4.2.2 Volatile Solids (VS) or Organic Dry Matter (ODM) ........................................ 52
4.2.3 Chemical Oxygen Demand (COD) .................................................................. 53
4.2.4 Biochemical Oxygen Demand (BOD) ............................................................. 54
4.2.5 Turbidity ......................................................................................................... 55
4.2.6 pH................................................................................................................... 55
4.2.7 Conductivity ................................................................................................... 56
4.3 Heavy Metals (Cd, Pb and Zn). .......................................................................... 56
4.4 Pathogenic Indicator Organisms ......................................................................... 58
4.4.1 Total Coliforms (TC) ...................................................................................... 59
4.4.2 Fecal Coliform (FC) ........................................................................................ 60
4.4.3 Escherichia coli ............................................................................................... 61
4.4.4 Salmonella Species ......................................................................................... 62
CHAPTER FIVE ................................................................................................... 64
5. CONCLUSION AND RECOMMENDATION ................................................. 64
5.1 Conclusion ......................................................................................................... 64
5.2 Recommendations.............................................................................................. 65
REFERENCES ...................................................................................................... 66
APPENDIX ............................................................................................................ 77
Appendix 1: Reagents for TKN analysis: ................................................................. 77
Appendix 2: Reagents for NH -N ............................................................................ 77
4
Appendix 3: Reagents for Total Phosphorus ............................................................ 77
Appendix 4: Reagent for Potassium ......................................................................... 78
Appendix5 Calibration of pH meter with buffer solution......................................... 78
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Appendix 6: Means of the twin biogas plant at Ashaiman ........................................ 79
Appendix 7: Effluent storage compartment of the twin digester in Ashaiman, covered
with roofing sheets to prevent ammonia loss to the atmosphere ........................... 80

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