Determination Of Wood Species Utilized In Selected Sawmills, Waste Volumes And Preference For Domestic Energy In Abia State, Nigeria

ABSTRACT

Waste generation is a concomitant aspect of living; it cannot be banished but can only be managed. Wood Species utilized in selected sawmills, volume of wood wastes and its preference for domestic energy in Abia State was carried in Timber markets of Aba North, Umuahia North and Bende Local Government areas of Abia State. The processed wood species were identified and their abundance determined; the number and volume of logs and also that of the converted lumber were determined and then the volume of wood wastes generated in the timber sawmills were evaluated. Menhinick’s Index (D) was used to calculate the proportional abundance of the processed wood species. The findings show that across the three local government areas, wood species encountered were not abundantly diversed in their sources of origin which is the forest. The sawmills had their indices values less than 1. Measurements of diameter at large end of log, diameter at mid-point of log, diameter at small end of log, length of sawn lumber, breadth and thickness of sawn lumber were taken for a period of six (6) days per week for twenty four (24) weeks. The overall mean values of number of logs converted per week in the three selected LGAs are Aba North (177.07), Umuahia North (183.90), Bende (150.43) while the overall mean volume of logs converted per week in the selected LGAs were Aba North (34.11m³), Umuahia North (33.32 m³), Bende (21.57 m³); the overall mean number of converted lumber per week in the three selected LGAs were Aba North (1124.72), Umuahia North (1045.68), Bende (705.23);the overall mean values of the volume of converted lumber per week were Aba North (26.36), Umuahia North (21.90), Bende (16.65). Correlation analysis revealed a significant negative correlation between volume of wood waste generated per week and volume of sawn timber processed among the surveyed sawmills (F17, 67 = 2.564, P = 0.003) and the locations (F2,97 = 5.557, P = 0.005). Also, there was a positive correlation between volume of wood wastes and volume of logs. The results showed that wood wastes species commonly used in the study areas are Gmelina (Gmelina arborea) with the highest percentage of preference of 17.36%. This was followed by Teak (Tectonia grandis) with a preference value of 13.22%. The people also preferred Ceiba (Ceiba pentandra) wood wastes, with a value of 9.92%, and Obeche (Triplochiton scleroxylon), having a percentage value of 6.17% followed by Ekki (Lophira alata) and Iroko (Milicia excelsa) with a value of 4.10%. Other wood waste species are also preferred in various insignificant percentages. The Chi-square (x²) statistical analysis shows that at 5% level of probability (p<0.05), the wood wastes species used in the study locations were not significantly different. Furthermore, alternative sources of energy should be encouraged and also the public should be advised on the need to participate in afforestation programmes because of the indiscriminate exploitation of the forest.

TABLE OF CONTENTS

Title page i

Declaration ii

Certification iii

Dedication iv

Acknowledgements v

Table of Contents vi

List of Tables ix

List of Figures x

List of Plates xi

Abstract xii

CHAPTER 1: INTRODUCTION

1.1 Background of the Study 1

1.2 Statement of Problem 13

1.3 Objectives of Study 13

1.4 Significance of the study 14

1.5 Scope of the Study 16

CHAPTER 2: LITERATURE REVIEW

2.1 The Potential Use of Wood Residue for Energy Generation 23

2.2 Utilization of Wood Waste for Energy Generation 25

2.3 Sources of Wood Wastes 27

2.4 Forest Residues 33

2.5 Mill-Site Generated Wood Waste 36

2.6 Integrated Production 39

2.7 Alternative Uses of Residues 40

2.8 Uses of Wood Waste 41

2.8.1 Fuel production 41

2.8.2 Briquettes 41

2.8.3 Pellets 42

2.8.4 Wood chips 42

2.8.5 Charcoal 42

2.8.6 Bark utilization 42

2.8.7 On-site energy generation 43

2.9 Heat Generation and Incineration 43

2.10 Strict Heat Generation 43

2.11 Heat and Power Generation 44

2.12 Problems of Wood Waste to the Environment 44

2.13 Management of Sawmill Wastes in Nigeria 47

2.14 Wood Wastes Management Strategies 53

2.15 Management Options for Wood Wastes 55

2.15.1 Briquette production 55

2.15.2 Hard board 56

2.15.3 Particle board 56

2.15.4 Fibre board 57

2.15.5 Absorbents and landscape uses 57

2.16 Prospects for Optimizing Wood Waste Utilization in Nigeria 58

2.17 Classification of Wood Waste 59

2.18 Characterization of Wood Waste 60

2.19 Environmental Challenges of Wood Disposal 61

2.20 Prospects of Wood Waste Gasification for Power Production 64

2.21 Wood Waste Energy in Foreign Countries 64

CHAPTER 3: MATERIALS AND METHODS

3.1 Study Area 69

3.2 Sources of Data 73

3.3 Sampling Technique/Research Design 73

3.4 Data Collection 74

3.5 Experimental Procedure 75

3.5.1 Identification and estimation of the processed wood species abundance 75

3.5.2 Determination of log volume 76

3.5.3 Determination of lumber volume 76

3.5.4 Wood waste volume computation 77

3.5.5 Sawmill conversion efficiency 77

3.5.6 To compare the use of wood wastes of different tree species for energy 77

3.6 Data Analysis and Experimental Design 78

CHAPTER 4: RESULTS AND DISCUSSION

4.1 Identification of the Processed Wood Species in the Mills 79

4.2 Determination of the Identified Wood Species Abundance in the Mills 82

4.2.1 Estimation of the wood species abundance using Menhinick’s index 91

4.3 Determination of the Number and Volume of Logs in the Study Areas 94

4.3.1 Determination of the number of the logs in the study areas 94

4.3.2 Determination of the volume of logs in the study area 100

4.3.2.1 Determination of log volume converted in the sawmills 105

4.4 Determination of the Number and Volume of Converted Lumber in the

Study Areas 106

4.4.1 Determination of the number of sawn lumber converted in the study areas 106

4.4.1.1 Determination of number of lumber converted in the sawmills 111

4.4.2 Determination of the volume of sawn lumber converted in the study areas 112

4.4.2.1 Determination of lumber volume 117

4.5 Determination of the Volume Wood Wastes 118

4.5.1 Determination of the volume of wood wastes in the study area 118

4.5.2 Wood waste volume computation 123

4.5.3 Determination of the percentage volume of wood wastes in the study area 125

4.6 Conversion Efficiency of the Sawmill 131

4.6.1 Determination of conversion efficiency of the sawmill 131

4.6.2 Sawmill efficiency 136

4.7 Comparison of the Use of Wood Waste for Energy 145

4.7.1 Demographic data of respondents 145

4.7.2 Comparison of wood species wastes preference and reasons for

preference 147

CHAPTER 5: CONCLUSION AND RECOMMENDATIONS

5.1 Conclusion 150

5.2 Recommendations 151

5.3 Contribution to Knowledge 152

5.4 Suggestion for Further Research 152

REFERENCES 153

APPENDIX 166

QUESTIONNAIRE 167
LIST OF TABLES

2.1: Sources of wood residue 28

2.2: Several outlet areas 40

4.1.1: Wood species identified in all the selected sawmills across the

three local government areas 80

4.2.1: Number of wood frequencies encountered in the sawmills of Aba

North Local Government Area 85

4.2.2: Number of wood frequencies encountered in the sawmills of

Umuahia North Local Government Area 88

4.2.3: Number of wood frequencies encountered in the sawmills of

Bende Local Government Area 90

4.2.4: Menhinick’s Index values across the various sawmills in the three

local government areas 93

4.3.1: Number of logs converted per week in the three selected LGAs of

Abia State 96

4.3.2: Volume of logs converted per week in the three selected LGAs

of Abia State 102

4.4.1: Number of converted lumber per week in the three (3) selected

LGAs of Abia State 108

4.4.2: Volume of converted lumber per week in the three selected

LGAs of Abia State 114

4.5.1: Volume of wood waste generated per week in the three (3)

selected LGAs of Abia State 120

4.5.2: Percentage volume of wood waste generated per week in the

three selected LGAs of Abia State 127

4.6.1: Conversion efficiency of the sawmills in the three selected

LGAs of Abia State 133

4.7: Categorical description of sawmill operations across three Local Government Areas in Abia State 142

4.8 The relationship between volumes of logs and volumes of sawn

timber for the purpose of predicting the wood wastes 144

4.9.1: Demographic data of the respondents 146

4.9.2: Comparison of wood species wastes preference and reasons for preference 149

LIST OF FIGURES

3.1: Map of Abia State indicating the study locations 72

4.1: Mean value of the number of logs converted in the three study areas 98

4.2: Differences in the number of logs converted per week in sawmills located

in Abia State 99

4.3: Mean values of the volume of logs converted in the three study areas 104

4.4: Volumes of logs converted per week in sawmills located in Abia State 105

4.5: Mean values of the number of sawn lumber in the three study areas 110

4.6: Variation in the number of sawn timber per week in sawmills located in

Abia State 111

4.7: Mean values of the volume of sawn lumber in the three study areas 116

4.8: Distribution of volumes of sawn timber per week in sawmills located in

Abia State 117

4.9: Mean values of the volume of wood wastes in the three study areas 122

4.10: Differences in the volumes of wood waste generated per week in sawmills

located in Abia State 123

4.11: Relationship between the volume of wood waste and volumes of sawn

timber in sawmills located in Abia State 124

4.12: Mean values of the percentage volume of wood wastes in the three study

areas 129

4.13: Differences in the percentage volume of wood waste generated per week

in sawmills located in Abia State 130

4.14: Variation in sawmill efficiency in sawmills located in Abia State 137

4.15: Mean values of the sawmill efficiency in the three study areas 138

4.16: Variations in the impact of sawmill efficiency on percentage wood waste

generated per week across sawmills in the surveyed locations 139

4.17: Differences in conversion ratio in sawmills located in Abia State 140

4.18: The impacts of volume of log converted and volume of sawn timber on

volume of wood waste generated across locations and sawmills in Abia

State 144

LIST OF PLATES

2.1: Saw dust waste produced by vertical band saw 27

2.2: Pictorial diagram of a heap of Sawmill 33

2.3: Pictorial diagram of a heap of Offcuts 35

2.4: Wood Shavings gotten from wood conversion 53

2.5: Harvesting of some of the tree species used 63

2.6: Logs ready to be measured before conversion 65

2.7: Wood chips 66

2.8: Wood shavings 66

2.9: Wood bark 67

2.10: Sawdust 67

2.11: Wood offcuts 68