Solar Thermophilic Anaerobic Reactor

248 Pages·2003·1.95 MB·English

Solar Thermophilic Anaerobic Reactor (STAR) for
Renewable Energy Production
Hamed El-Mouafy Hamed El-Mashad
Promotoren:
Prof. dr. ir. G. P.A. Bot
Hoogleraar in de technische natuurkunde
Prof. dr. ir. G. Lettinga
Hoogleraar in de anaërobe zuiveringstechnologie en hergebruik van afvalstoffen
Co-promotoren:
Dr. ir. G. Zeeman
Universitair docent bij de sectie Milieutechnologie van het Departement Agrotechnologie en
Voedingswetenschappen
Dr. ir. W. K.P. van Loon
Universitair docent bij de leerstoelgroep meet-regel- en systeemtechniek
Samenstelling promotiecommissie:
Prof.dr. B.K. Ahring The Technical University, Denmark
Prof.dr.ir. W.H. Rulkens Wageningen Universiteit, Nederland
Dr.ir. A.F.M. van Velsen Haskoning B.V., Nederland
Dr. ir. W.G.J. van Helden ECN, Nederland
Solar Thermophilic Anaerobic Reactor (STAR) for
Renewable Energy Production
Hamed El-Mouafy Hamed El-Mashad
Proefschrift
ter verkrijging van de graad van doctor
op gezag van de rector magnificus
van Wageningen Universiteit,
prof. dr. ir. L. Speelman,
in het openbaar te verdedigen
op donderdag 18 december 2003
des namiddags te half twee in de aula
Author: El-Mashad, H.M.
Title: Solar Thermophilic Anaerobic Reactor (STAR) for Renewable Energy Production
Thesis Wageningen University, Wageningen, the Netherlands- with summary in Dutch
Publication year: 2003
ISBN: 90-5808-953-3
Keywords: solar energy, thermophilic anaerobic digestion, biogas, temperature fluctuation,
ammonia inhibition, hydrolysis, agricultural wastes, cattle manure, rice straw, emergy
To my parents, Fayz,
Malaka and Mohamed
ABSTRACT
El-Mashad, H.M. (2003). Solar thermophilic anaerobic reactor (STAR) for renewable
energy production. Ph.D. Thesis, Wageningen University, Wageningen, The Netherlands.
Liquid and solid cattle manures are major waste streams in Egypt. The main objective
of this research was maximising the net energy production from these wastes by using a solar
energy heating system. High concentration of ammonia can strongly affect the gross methane
production via inhibition of methanogenesis and reduced hydrolysis. The latter is only limited
addressed so far in literature and therefore taken as a second objective of this study.
To be able to design a solar thermophilic anaerobic reactor (STAR) and its pumping
system, the effect of temperature on the rheological properties of liquid cattle manure was
measured experimentally. The effect of temperature and temperature fluctuations on the
performance of completely stirred tank reactor (CSTR) systems operated at 50oC and 60oC
treating liquid cattle manure was studied also experimentally. The temperature fluctuations of
the reactor content in a STAR system, designed without extra equipment for heating during
the night, shown to be in a range, which will not significantly affect the biological activity in
the reactor.
Simulations were carried out to study the effect of the interaction between different
reactor volumes and different insulation materials on the net thermal energy production from
the STAR system at Egyptian climatic conditions. Using a flat plate solar collector, with
areas equal to the reactor’s cross section area, improves the efficiency for large reactors only
slightly, while for small reactors a large improvement is achieved.
The feasibility of a non-mixed accumulation system (AC) for treatment of solid
manure was studied experimentally at 40 and 50oC and filling time of 60 days using a 10%
(V/V) inoculum placed on the reactor bottom. The results showed a distinct stratification of
intermediates along the reactor height. Leachate recirculation and distribution of the
inoculum with the feed could improve the system performance: higher methane production
with less stratification extent. The results of a mechanistic model, describing the biological
process in AC system including the dispersion of intermediates and bacteria species between
the system layers showed a very well agreement with the experimental data of the methane
production.
Finally, a design of a STAR for solid cattle wastes was studied in a model. The
simulation results show that a minimum reactor temperature of 44.5 during summer and
47.6oC during winter could be achieved for a well-insulated reactor with an aspect ratio of
0.6.
The effect of different ammonia concentrations on the hydrolysis constant (k ) of
h
liquid cattle manure was also studied experimentally at 50 and 60oC. Negative linear relations
between k and both total and free ammonia concentrations were found at each studied
h
temperature.
From a literature review it becomes clear that next to animal manure rice straw is an
important waste stream from the Egyptian agriculture. Combined composting of digested
manure mixed with rice straw could produce an attractive organic fertiliser.
Based on emergy analysis of the system, the STAR concept can be recommended
from the sustainability point of view.
Contents
CHAPTER 1 GENERAL INTRODUCTION 1
1.1. Problem statement and fields of interest 2
1.2. The objectives 3
1.3. Overview this dissertation 3
CHAPTER 2 REUSE POTENTIAL OF AGRICULTURAL WASTES IN SEMI-ARID
REGIONS: EGYPT AS A CASE STUDY 5
2.1. Introduction 6
2.2. Agricultural wastes in Egypt 8
2.2.1. Crop residues 8
2.2.2. Animal manure production 9
2.3. General technologies for biomass conversion 9
2.3.1. Combustion 11
2.3.2. Gasification 11
2.4. Reuse of rice straw 12
2.4.1. Rice straw composition 12
2.4.2. Rice straw combustion 13
2.4.3. Combustion systems and their efficiencies 13
2.4.4. Problems with rice straw combustion and gasification 15
2.4.5. Biomethanation of rice straw 17
2.4.6. Composting of rice straw 17
2.4.7. Rice straw incorporation in soils 18
2.5. Reuse of manure 18
2.5.1. Manure composition 19
2.5.2. Biomethanation of manure 20
2.5.3. Manure composting 20
2.6. A framework of biomethanation and composting for rice straw and manure 21
2.7. Conclusion and future perspective 23
CHAPTER 3 LITERATURE REVIEW 25
3.0. Introduction to the Chapter 26
3.1. Anaerobic Digestion Process: A General Overview 27
3.1.1. Background 27
3.1.2. Chemical; physical and thermal properties of cattle manure 28
3.1.3. The digestion process 29
3.1.4. Kinetics and modelling of the anaerobic digestion process 30
3.1.5. Anaerobic digestion systems for animal wastes 31
3.1.6. Factors affecting the process performance/stability 33
3.1.7. Gas handling and utilisation 36
3.1.8. Effluent utilisation as fertilisers 36
3.1.9. Application of solar energy for heating biogas units 37
3.2. Ammonia and Anaerobic Digestion Process: A Review 38
3.2.1. Introduction 38
3.2.2. Positive effect of ammonia presence 39
3.2.3. Negative effects of ammonia (i.e. inhibition/toxicity) 42
3.2.4. Adaptation of microflora 46
3.2.5. Mechanisms of ammonia inhibition 50
3.2.6. Kinetics and modelling 54
3.2.7. Ammonia mitigation 56
3.2.8. Post treatment 58
3.2.9. Conclusions and future perspectives 58
Nomenclature 59
CHAPTER 4 DIGESTION OF LIQUID COW MANURE 61
4.0. Introduction to the Chapter 62
4.1. Rheological Properties of Dairy Cattle Manure 63
4.1.1. Introduction 63
4.1.2. Materials and methods 64
4.1.3. Results and discussion 65
4.1.4. Conclusions 69
4.2. Effect of Temperature and Temperature Fluctuation on Thermophilic Anaerobic
Digestion of Cattle Manure 70
4.2.1. Introduction 70
4.2.2. Materials and methods 72
4.2.3. Data processing 75
4.2.4. Results and discussion 76
4.2.5. General discussion 87
4.2.6. Conclusions 88
4.3. Effect of Ammonia on Thermophilic Anaerobic Hydrolysis of Dairy Cattle Manure 89
4.3.1. Introduction 89
4.3.2. Materials and methods 90
4.3.3. Data processing 92
4.3.4. Results and discussion 94
4.3.5. Final discussion and conclusions 101
4.4. A Model of Solar Energy Utilisation in the Anaerobic Digestion of Cattle Manure 102
4.4. 1. Introduction 102
4.4. 2. Materials and methods of the experimental work 103
4.4. 3. Modelling 105
4.4. 4. Results and discussion 108
4.4. 5. Conclusions 112
4.5. Design of A Solar Thermophilic Anaerobic Reactor (STAR) for Small Animal Farms 114
4.5.1. Introduction 114
4.5.2. Measurements 115
4.5.3. Mathematical model of the studied systems 116
4.5. 4. Results and discussion 124
4.5.5.Conclusions 132
Nomenclature 133
CHAPTER 5 DIGESTION OF SOLID COW MANURE 135
5. 0. Introduction to the Chapter 136
5.1. Anaerobic Digestion of Solid Animal Waste in An Accumulation System at
Mesophilic and Thermophilic Conditions, Start Up 137
5.1.1. Introduction 137
5.1.2. Materials and methods 138
5.1.3. Results and discussion 141
5.1.4. Conclusions 148
5.2. Effect of Inoculum Addition Modes and Leachate Recirculation on Anaerobic
Digestion of Solid Cattle Manure in an Accumulation System 150
5.2.1. Introduction 150
5.2.2. Materials and methods 151
5.2.3. Results and discussion 154
5.2.4. General discussion 159
5.2.5. Conclusions 161
5.3. A Model for Anaerobic Digestion of Solid Cattle Wastes in a Stratified Thermophilic
Accumulation System 162
5.3.1. Introduction 162
5.3.2. Material and methods 163
5.3.3. Modelling 164
5.3.4. Results and discussion 170
5.3.5. General discussion and conclusion 176
Notation 177
5.4. Design of A Layered Accumulation System for Thermophilic Anaerobic Digestion of
Solid Manure Heated with Solar Energy
178
5.4.1. Introduction 178
5.4.2. Methodology 179
5.4.3. Results and discussion 184
5.4.4. General discussion 189
5.4.5. Conclusions 190
Notation 191
CHAPTER 6 GENERAL DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS 193
6.1. Reuse potential of agricultural wastes in Egypt 194
6.2. Effect of ammonia 194
6.3. Treatment of liquid manure: Effect of temperature and solar energy incorporation 195
6.4. Treatment of solid manure: Effect of temperature and solar energy incorporation 197
6.5. System evaluation: EMergy analysis of the STAR 199
6.6. Practical application 200
6.7. Recommendations and most important conclusions 203
REFERENCES 205
APPENDICES 223
Appendix A: Some symbols used in EMERGY analysis 224
Appendix B: Some calculations of EMERGY analysis 225
ENGLISH SUMMERY 228
DUTCH SUMMERY 232
ACKNOWLEDGEMENTS 236
CURRICULUM VITAE 237