Table of Contents

Chapter1 Introduction to Biogas
1.1 Biogas Origin & Nomenclature ／ 1
1.2 International Biogas History ／ 2
1.3 Biogas Digester Development in China ／ 7
1.3.1 First Stage—Luo Guorui Biodigester ／ 7
1.3.2 Second Stage—Long—distance， Big and Deep Digester ／ 7
1.3.3 Third Stage—Round， Small and Shallow Digester ／ 8
1.3.4 Fourth Stage～Mini—size and High—efficiency Digester ／ 8
1.3.5 Fifth Stage—Commercialized Fiberglass Digester ／ 9
1.4 Biogas Characteristics ／ 9
1.4.1 Biogas Components ／ 9
1.4.2 Biogas Terminologies ／ 10
1.4.2.1 Total Solids （TS） ／ 10
1.4.2.2 Volatile Solids （VS） ／ 10
1.4.2.3 Hydraulic Retention Time （HRT） ／ 11
1.4.2.4 Gas Production Rate （GPS） ／ 11
1.4.2.5 Organic Space Loading Rate （OLR） ／ 12
1.4.2.6 Gas Production Rate of Materials （GPRM） ／ 13
1.4.2.7 Biochemical Oxygen Demand （BOD） ／ 14
1.4.2.8 Chemical Oxygen Demand （COD） ／ 14
1.4.2.9 The Relationship of the Biogas Parameters ／ 15
Chapter2 Biochemistry and Microbiology of Biogas Fermentation
2.1 Three Steps of Biogas Fermentation ／ 17
2.2 Microbes in Three—step of Biogas Fermentation ／ 19
2.2.1 Biogas Microbes in Nature ／ 19
2.2.2 Groups and Actions of Non—methane—producing Microbes ／ 20
2.2.2.1 Variety of Non—methane—producing Microbes ／ 21
2.2.2.2 Amount of Non—methane—producing Microbes ／ 23
2.3 Estimation and Calculation of the Amount of Methane Produced
from Organic Compounds ／ 24
2.4 Anaerobic Digestive Process of Complex Organic Compounds ／ 26
2.4.1 The Degradation of Carbohydrates ／ 26
2.4.1.1 Anaerobic Degradation of Glucose ／ 26
2.4.1.2 Anaerobic Degradation of Cellulose ／ 27
2.4.1.3 The Metabolism of Semi—cellulose， Pectin—gel， Starch，and Cellulose under Anaerobic Conditions ／ 29
2.4.2 Metabolism of Lipids ／ 29
2.4.3 Metabolism of Protein ／ 30
2.5 Fermentative Bacteria ／ 31
2.5.1 Cellulose—splitting Bacteria ／ 31
2.5.2 Semi—cellulose—splitting Bacteria ／ 32
2.5.3 Starch—splitting Bacteria ／ 32
2.5.4 Protein—splitting Bacteria ／ 32
2.5.5 Fat—splitting Bacteria ／ 33
2.6 The Obligate H2—producing Acetogenic Bacteria ／ 33
2.7 Hydrogen—producing Acetogenic Bacteria in Aqua of Biogas Fermentation ／ 36
2.7.1 Hydrogen—Producing Acetogenic Bacteria in Biogas Fermentation Liquid ／ 36
2.7.2 Other Specific Bacteria ／ 36
2.8 Methane—producing Bacteria and Their Classification ／ 37
2.8.1 Classification and Identification of Methane—producing Bacteria ／ 37
2.8.1.1 Characteristics of Methane—producing Bacteria ／ 37
2.8.1.2 The Third Fashion of Life ／ 38
2.8.1.3 Morphology and Classification of Methane—producing Bacteria ／ 39
2.8.2 Metabolic Substrates of Methane—producing Bacteria ／ 44
2.8.3 Theory of Methane Formation ／ 45
2.8.3.1 Theory of Carbon Dioxide Reduction ／ 45
2.8.3.2 Theory of Methyl Group Directly Convert to Methane ／ 45
2.8.3.3 Barker's Hypothesis ／ 45
2.8.4 Methane Formation Metabolized by Acetate and Formate ／ 46
2.8.5 Methane Original ／ 47
2.9 Relationship Between Different Biogas Microbes ／ 47
Chapter3 Technology of Biogas Fermentation
3.1 Strict Anaerobic Environment ／ 50
3.2 Temperature ／ 51
3.3 pH Value ／ 53
3.4 Feedstock for Biogas Fermentation ／ 54
3.4.1 Properties and Classification of Feedstock ／ 54
3.4.1.1 Nitrogen—rich Raw Material ／ 54
3.4.1.2 Carbon—rich Raw Material ／ 54
3.4.2 Properties of Common Feedstock in Gas Production ／ 55
3.4.2.1 Rate of Gas Production of Feedstock ／ 56
3.4.2.2 Speed of Gas Production ／ 56
3.4.3 Proportion of Feedstock ／ 57
3.4.3.1 Ratio of Carbon and Nitrogen （C／N） ／ 57
3.4.3.2 Manure： Straw Ratio ／ 58
3.5 Concentration ／ 59
3.6 Seeding Materials ／ 62
3.6.1 Function of Seeding Materials ／ 62
3.6.2 Enrichment and Culture of Seeding Materials ／ 63
3.6.3 Source of Seeding Materials ／ 63
3.6.4 Amount of Seeding Material ／ 64
3.7 Management ／ 64
3.7.1 Supplement of Fresh Raw Materials ／ 64
3.7.2 Frequent Stirring ／ 64
3.7.3 Keep Fermentative Temperature ／ 65
3.7.4 Frequent Check of Biogas Devices ／ 65
3.7.5 Discharging Digesters ／ 65
3.7.6 Fermentation Inhibitors ／ 65
3.7.7 Safety & Biogas Appliances ／ 66
3.8 Inspection and Maintenance of the Biogas Digester ／ 69
3.8.1 Leak Test of the Biogas Digester ／ 69
3.8.1.1 Test Methods ／ 69
3.8.1.2 Air Leakage Standard ／ 70
3.8.2 Biogas Digester Maintenance ／ 70
3.9 Technique Types of Biogas Fermentation ／ 71
3.9.1 According to Feeding Pathway ／ 71
3.9.1.1 Batch Fermentation ／ 71
3.9.1.2 Semi—continuous Fermentation ／ 71
3.9.1.3 Continuous Fermentation ／ 71
3.9.2 According to Digesting Device—type ／ 72
3.9.3 According to Fermentative Mold of Action ／ 72
3.9.4 According to State of Feedstock ／ 73
3.9.5 According to Fermentation Temperature ／ 73
3.9.6 According to Different Stage Fermentation ／ 73
3.10 Different Types of Fermentative Digesters ／ 74
3.10.1 Conventional Digester ／ 74
3.10.2 High Rate Digester ／ 75
3.10.3 Anaerobic Contact Digester ／ 75
3.10.4 Anaerobic Filter （AF） ／ 75
3.10.5 Up—flow Anaerobic Sludge Bed （UASB） ／ 76
3.10.6 Anaerobic Bed ／ 77
3.10.7 Two—phase Anaerobic Digester ／ 77
3.10.8 Dry Fermentation ／ 78
3.10.9 Plug—flow Anaerobic Digester ／ 79
3.10.10 Pipeline—type Anaerobic Digester ／ 79
Chapter4 Large—medium Scale Biogas Project
4.1 Partition of Large—medium Scale Biogas Project ／ 80
4.1.1 Partition by Volume Size ／ 81
4.1.2 Classifications by Different Types of Organic Wastes ／ 82
4.1.2.1 Livestock Farm Biogas Project ／ 82
4.1.2.2 Biogas Project of Industrial Waste ／ 82
4.1.2.3 Biogas Project of Municipal Sewage Purification ／ 83
4.1.3 Materials Characteristics ／ 84
4.1.4 Characteristics of Biogas Project ／ 84
4.1.4.1 Anaerobic Digestion Technology Advantages ／ 84
4.1.4.2 Anaerobic and Aerobic Bio—technology Comparison ／ 85
4.2 Process and Type of Biogas Project ／ 86
4.2.1 Anaerobic Contact Process ／ 86
4.2.2 Anaerobic Filter （AF） ／ 87
4.2.2.1 The Choice of Filter ／ 88
4.2.2.2 Filter Height of Anaerobic Filter ／ 88
4.2.2.3 The Actual Effect of Anaerobic Filter ／ 88
4.2.3 Upflow Anaerobic Sludge Blanket （UASB） ／ 89
4.2.3.1 Operational Principle of UASB Reactor ／ 91
4.2.3.2 UASB Reactor Startup ／ 91
4.2.3.3 Application of UASB Reactor ／ 92
4.2.3.4 Attentions of UASB Application ／ 96
4.2.4 Anaerobic Fluidized Bed （AFB） and the Anaerobic Attached
Film Expanded Bed （AAFEB） ／ 97
4.2.5 Expanded Granular Sludge Bed （EGSB） ／ 98
4.2.6 Internal Circulation Anaerobic Reactors （IC Reactor） ／ 99
4.2.7 Upflow Anaerobic Sludge Bed—filter Technology （UBF） ／ 101
4.2.8 Upflow Anaerobic Solid Reactor （USR） ／ 101
4.2.9 Anaerobic Rotating Biological Contactor （ARBC） ／ 102
4.2.10 Anaerobic Baffled Reactor （ABR） ／ 102
4.3 The Design and Management of Biogas Engineering ／ 104
4.3.1 The Design of Biogas Engineering ／ 104
4.3.1.1 General Requirements ／ 104
4.3.1.2 The Volume Determination of Anaerobic Digestion Plant ／ 104
4.3.1.3 Ancillary Equipment of Large—medium Scale Biogas Engineering ／ 105
4.3.2 The Startup of Biogas Engineering ／ 105
4.3.2.1 Preparations ／ 105
4.3.2.2 Sludge Inoculation ／ 105
4.3.3 Operation and Management of Biogas Engineering ／ 106
4.3.3.1 Operation and Management of Biogas Engineering ／ 106
4.3.3.2 Maintenance of Large Biogas Engineering ／ 106
……
Chapter5 Engineering of Domestic Sewage Treatmentin Towns and Non—hazardous Treatment
Chapter6 Introduction and Background to Compre—hensive Utilization of Biogas System
Chapter7 Utilization of Biogas
Chapter8 Utilization of Bio—slurryin China
Chapter9 Characteristics of Bio—slurry
Chapter10 Various Kinds of Utilizations of Bio—slurry
Chapter11 Effect Evaluationon the Utilization of Bio—slurry
Chapter12 Commercialized Household Biogas Digester Made of Glass Fiber Reinforced Plastic
Chapter13 The Practices of Fiberglass Bio—digester

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Preface

Biogas technology plays a unique role in the treatment processes of organic solid disposal and waste water, and it is an effective way of reusing of organic wastes, such as energy recovery from wastes. Over the past 100 years, the theoretical deve- lopment of biogas technology has brought about numerous techniques in a wide prospect. More than 40 years of application in China, household biogas digesters play an important role in solving problems concerning rural and agricultural sus- tainable development in developing countries (e.g. making up for shortage of rural energy). From the perspective of energy development, biogas technology, as a zero- CO2-emission-technology, generates energy with decomposed organic wastes which can cause environmental pollution, and doesn't emit CO2 in atmosphere. Rural biogas application has provided remarkable benefits concerning society, ecology, energy and economy, and the comprehensive utilization of biogas and its residue has formed different ecological agriculture modes such as the "four in one" mode in north of China and "pig-biogas-fruits" mode in south of China, and these modes reflect the reasonable connotation of sustainable agriculture, which is future way of agriculture development in developing countries. At present, rural household biogas digester popularizes rapidly, and many government agencies, international organizations and NGOs in the world have been devoted to construction of biogas in developing countries. In 2007, Netherlands government raised 2 billion euros in the world to install 2 million rural household biogas digesters in Africa, and then, Asian Bank established a plan of promoting 0.15 million household biogas digester in 15 countries of Asia (in this plan, Asian Bank provide 1/3 subsidy funds and 1/3 loans).
Facing the fossil fuels crisis and environment deterioration, biogas, as a kind of renewable energy, has been attached to great importance in many developed countries. In Europe, large biogas projects develop rapidly, and its scale becomes bigger over time, and the ratio of biogas in the energy consumption is rising. Large and medium-size biogas projects are widely used to treat different pollutants (e.g. livestock and poultry breeding waste water, industry organic waste water, kitchen waste, sewage and domestic waste) to realize pollution control, energy recovery, resource utilization. In nature, organic material is decomposed through two bioche- mical ways, i.e. anaerobic and aerobic processes. Compared to aerobic technology, anaerobic process has many advantages such as: ① anaerobic fermentation can withstand the high concentration of organic load; ② energy consumption of this process is only 1/10 of the aerobic process; ③ the amount of sludge of this process is far less than the aerobic treatment; ④ this kind of fermentation can bring economic profits (resulting from biogas and organic fertilizer) as well as environ- mental benefit. Therefore, anaerobic digestion technology has been widely used to treat high concentration organic waste water and waste, and promote the develop- ment of high yield, high quality, highly effective, ecology and safety agriculture.
By anaerobic digestion, pathogenic bacteria and eggs in organic waste can be killed, and biogas slurry (as a kind of efficient and safety organic fertilizer) can be produced, and refractory pesticides such as DDT can be effectively degraded. Generally, Biogas technology and engineering can: ① convert excrement to resources, promote the sustainable development of animal husbandry; ② develop green agriculture by using biogas fermentation residues as fertilizer; ③ realize energy recovery; ④ treat waste water, recycle irrigation and realize zero discharge.
This book is a systematical summary of author's practice of nearly 30 years and 5 years training materials that were prepared for biogas technology international training workshops which were supported consecutively by Ministry of Science and Technology of China and Yunnan Provincial Science and Technology Department from 2008 to 2012. Based on a large number of domestic and foreign literatures, this book tries to build the systematical theory, show detailed technology and process, and display latest research results. So, this book has readability and practicability.
In the process of writing, the authors got the care and help from leaders and colleagues, the understanding and support from family. The publication of this book also condensed the hard work of chemical industry press editors. So, by the publication of this book, I want to express my heartfelt thanks for all people and units above.
Because of our limitations, the omissions are inevitable, sincerely welcome criticisms from relevant experts and readers.

Wudi Zhang
On February 26, 2016