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
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The Forest Estate in Nigeria
is estimated at about 10 million hectares, with about 20 % in reserve and also
vegetation types ranging from mangrove swamp, lowland rainforest and savanna
(Olaleye, 1999). In the past, Nigeria was endowed with abundant timber
resources but because of excessive exploitation of these resources the country
has less than 10 % of her land area under high forest. One element that has
added enormously to the rapid deletion of the country’s timber resources is
wastage of wood during log processing. No matter how perfect and modernized an
adopted technology in a sawmill may be, wood wastes will be generated. Although
the complete utilization of the whole tree harvested from the forest should be
the ultimate goal of every forest industry, waste would continuously be
produced.
Foremost among the
wood based industries where wood wastes are generated are sawmills, carpentry
workshops, furniture mills and furniture workshops. Wood wastes generation in
the particle board and pulp and paper mills are comparatively reduced. Lucas
(1984) distinguished between inevitable and avoidable wood wastes. Even when
the Kerf is low and the mill workers are efficient, unavoidable wastes cannot
be avoided. Sawdust, inconvertible slabs, and strips are among them. Unwanted
waste is produced by a lack of (i) log pre-inspection and (ii) saw maintenance.
They include sub-standard timber which were inaccurately manufactured because
of faults in the circular resaw machine. Wood-based industrial operations in
Nigeria that generate one type of wood waste or the other include timber
logging, sawmilling, wood-b9ased panel products manufacturing (i.e. plywood,
fibre board and particleboard), furniture/joinery making, paper making, match
making, wood seasoning and the manufacture of various wooden items such as tool
handles, sport goods, weaving equipment and wooden toys. Also, there are allied
industries that make use of forest products for various purposes such as
building, mining, packaging, leather tanning and others and these produce various
grades of wood wastes.
Sambo (2009)
estimated that Nigeria has sawdust resources of 1.8 million tonnes. As the
demand for wood and its products grows, so does the volume of trash generated.
These wastes are burned in the open air in the lack of adequate disposal
measures. As a result, one of the most pressing environmental issues
confronting the industry today is how to appropriately dispose of the waste
generated everyday by the ever-increasing activities of timber operators. Waste
generation is an unavoidable part of life; it cannot be abolished, but only
controlled (Odewunmi, 2002). Similarly, wood wastes generation is inevitable
either during felling of trees for log production in the forest or diverse
sawing processes of logs/planks at the mills. Saw dusts, wood off cuts, trimmings,
edges, wood barks, simple shavings, wood rejections, cut slabs, and strips are
examples of wood residues created during milling and re-sawing activities, and
their origin may be traced back to the 18th century (Akachuku, 2000). Locally,
these residues are often used as filling material, poultry/animal bedding
material, mulch, raw material for particle board making, and cooking fuel.
Timber markets are
largely wood processing firms that have made major contributions to the
economic growth of numerous societies since their inception. The number of
timber markets in the country is increasing due to the high demand for wood and
wood products. Because of the low installed technology and inadequate
processing machines and other accessories, large quantities of wood wastes are
generated regularly in these sawmills (Ero, 1998). The amount of wood wastes
generated in these sawmills is immense and with the combination of the disposal
problems in the area, these wood wastes pose serious environmental problems in
Nigeria. Wood waste recycling is a technology adopted to minimize the loss of
the useful potentials of wood. There are so many uses wood wastes can be put
into which will ensure maximizing in full, the useful potentials of wood. The
major aim of timber management is to ensure overall utilization of logs.
Planned efforts for the profitable utilization of the various groups of wastes
represent the package referred to as management strategies. Timber supply
sustainability concept negates wastages of harvested timbers in whatever form.
Wastes in the form of sawdust, bark, trimmings, off-cuts, rejects (dumped sawn
boards, arising from rot and decay) and slabs will always be generated in
sawmills and other forest industries.
In most developed
countries, most wood-based industries utilize almost all the parts of the wood
transported into the industry. The heat energy required in the industry is
derived from the wood (Scotland, 2002). Most of the wood wastes are utilized
for wealth creation by recycling them to produce pulp for kraft paper,
resin-bonded particleboard, cement-bonded particle board, fibreboard, livestock
feed, compost formulation, packaging of fragile products such as china clay,
manufacture of industrial chemicals such as acetic acid, oxalic and methanol
(Akande and Badejo, 2000), production of mushroom (Adejoye and Fasidi, 2009),
chemicals (Balat et al., 2009),
enzymes, wood briquettes for use as fuel (Adegoke, 2006), charcoal
(Dionco-Adetayo, 2001), electricity and liquid biofuels especially methanol and
ethanol. Wood waste is generated by a variety of industries and is included in
the municipal garbage stream. Wood waste can be classified into several
fractions, ranging from untreated pre-consumer offcuts to treated wood
including preservatives and a variety of post-consumer trash (Oluoti et al., 2015).
The primary wood processing
businesses in Nigeria, such as sawmills, plywood mills, pulp and paper
facilities produce wood products on a huge scale. However, there are a great
number of small-scale wood enterprises that produce wooden products. Round-wood
in Nigeria is mostly sourced from the country's natural high forest zone,
including Cross River, Edo, Delta, Ogun, Ondo, Ekiti, Osun, and Oyo States
(Bello and Mijinyawa, 2010). Because of the increased demand for wood and wood
products, the country's number of individual timber sawmills is growing.
Because of the low installed technology and inadequate processing machines and
other accessories, large quantities of wood wastes are produced regularly in
these sawmills (Ero, 1998). The amount of wood wastes generated in these
sawmills is immense and with the combination of the disposal problems in the
area, these wood wastes pose serious environmental problems in Nigeria. Burning
wood wastes has become problematic because it releases high levels of carbon
dioxide, a greenhouse gas, which contributes to global warning. Particulate
materials from burning wood wastes may add to the improvement of smog in the
air. Such pollution poses serious threats to the environment. This necessitates
the prerequisite for environmental friendly technologies for the recycling of
wood wastes (Croan, 2000).
Over the years, many
sawmills have regarded wood waste as an inconvenient byproduct of the
sawmilling process, resulting in its disposal in landfills or incineration in
Wigwam burners or similar devices. However, both have recently become
contentious environmental issues and, combined with the rising cost of energy,
sawmill owners have been forced to seriously consider the merits of using the
residues as an alternative fuel source. This has also coincided with the
increase in demand for residues as furnish for paper-pulp and panel board
manufacture, due to the rising cost and increased competition for solid wood
(FAO, 2002).
Unlike most other businesses, the
forest industries have the advantage of being able to utilise their waste to
assist satisfy their energy requirements. The available residues can meet the
majority of the thermal energy requirements in mechanical wood processing. The
sawmill industry has the potential to generate both a surplus of heat and
electricity, which could be used to support other energy-deficient conversion
processes in an integrated complex producing, for example, lumber, plywood, and
particleboard, or, in rural areas, to supply energy for the needs of the
surrounding community (FAO, 2002).
Industries, electric power producers,
and commercial businesses use a significant volume of the wood and wood waste
fuel consumed in Nigeria. The wood and paper products industries use wood waste
to generate steam and power, which saves money by lowering the amount of other
fuels and electricity required. Some coal-burning power plants burn wood chips
to reduce sulfur dioxide emissions.
In most developed countries, most
wood-based industries utilize almost all the parts of the wood transported into
the industry. The heat energy needed in the industry is derived from the wood
(Scotland, 2002). Most of the wood wastes are also recycled to produce pulp for
kraft paper, resin-bonded particleboard, chemicals, livestock feed, compost
etc. The presence of hemicellulose in wood makes it a reliable source of
ethanol for industrial activities. In addition, in these developed countries,
there is growing market for wood wastes because of the particle size of wood
wastes, which enabled them to be used in most industrial processes, including
environmental protection as well as arable crop production (KPPC, 2004).
Sawmills, by their
very nature, generate much waste: sawdust, wood off-cuts, wood barks, plain
shavings, wood rejects, etc. In the absence of adequate disposal techniques,
these wastes are burned in the open air, deposited along stream and river
banks, or left to decay in any available place (Popoola et al., 2013). According to Sambo (2009), the amount of sawdust
produced in Nigeria ranges between 1.8 and 5.2 million tonnes per year. As the
demand for wood and its products grows, so, too, does the volume of trash
generated. Hence, one of the environmental problems facing cities and towns
today is not properly disposing the wastes being generated daily by the
ever-increasing activities of the sawmills (Babayemi and Dauda, 2010). If there
is a system failure or a complete lack of true and efficient waste management,
varieties of unpleasant situations become prevalent due to excess accumulation
of wood wastes, and may include flooding as a result of drains and waterways
being blocked during the raining season. They are also barriers in mills for
wood workers due to the exceptional accumulation of wastes over time, affecting
work rate negatively and eventually resulting to a reduction in output. As the
demand for wood and its products grows, so does the volume of trash generated.
These wastes are burned in the open air in the lack of adequate disposal
measures. Hence, one of the most serious environmental issues confronting the
industry today is how to properly dispose of the waste generated on a daily
basis by the ever-increasing activities of timber operators (Odewunmi, 2002). The
amount of wood waste produced from Timber industries has now become a problem
to the local environment. Even if some of the waste is used as domestic
firewood for household requirements and brick manufacturing enterprises, a
large portion of the wood waste in sawmills remains unused and must be disposed
of. Most industries just burn and/or dump garbage at the sites to clean up the
plant area. The open dumping and burning of wood waste eventually results in
the release of hazardous gases. These wastes cause numerous problems. They harm
the urban environment, impair its aesthetic value, emit foul odors during
rainstorms, and pollute the air with smoke when rubbish is burned
uncontrollably. When they are not properly disposed of, they also represent a
health risk. Worms and insects use them as breeding grounds. They also create a
hazardous working environment for people who operate in the region due to the
accumulation of debris over time.
Wood waste contribute
positively to electricity generation, large proportion of educational centres,
public, industrial and commercial buildings, homes etc have installed woodchip or wood pellet
heating systems. As a cost of fossil fuels continues to climb, and
environmental laws get tougher (and taxes higher), it is expected that using
wood wastes to heat buildings will become ever more popular. Wood waste is
generated by a variety of industries and is included in the municipal garbage
stream. Wood waste can be classified into several fractions, ranging from
untreated pre-consumer offcuts to treated wood including preservatives and a
variety of post-consumer waste.
Large capacity facilities, such as
sawmills, plywood mills, and pulp and paper plants, are typical of Nigeria's
major wood processing sectors. There are, nevertheless, a great number of
small-scale wood firms producing wooden products such as furniture, as well as
many cabinet builders and carpenters. Round-wood in Nigeria is primarily
sourced from the country's natural high forest zone, including the southern states
of Cross River, Edo, Delta, Ogun, Ondo, Ekiti, Osun, and Oyo (Bello and
Mijinyawa, 2010).
Industry, electric power producers,
and commercial businesses use most of the wood and wood waste fuel consumed in
Nigeria. The wood and paper products business uses wood waste to generate steam
and power, which saves money by reducing the amount of other fuels and
electricity needed. Some coal-burning power plants burn wood chips to reduce
sulfur dioxide emissions.
In most developed countries, most wood-based
industries utilize almost all the parts of the wood transported into the
industry. The heat energy needed in the industry is derived from the wood
(Scotland, 2002). Most of the wood wastes are also recycled to produce pulp for
kraft paper, resin-bonded particleboard, chemicals, livestock feed, compost
etc. The presence of hemicellulose in wood makes it a reliable source of
ethanol for industrial activities. In addition, in these developed countries,
there is growing market for wood wastes because of the particle size of wood
wastes, which enabled them to be used in most industrial processes, including
environmental protection as well as arable crop production (KPPC, 2004). Sawmills,
by their very nature, generate much waste: sawdust, wood off-cuts, wood barks,
plain shavings, wood rejects, etc. In the absence of appropriate disposal
procedures, these wastes are burnt in the open air, dumped along the bank of
streams and rivers or left on any available space to rot (Popoola et al., 2013). According to Sambo
(2009), the amount of sawdust produced in Nigeria ranges between 1.8 and 5.2
million tonnes per year. As the demand for wood and its products grows, so,
too, does the volume of waste generated. Hence, one of the environmental
problems facing cities and towns today is not properly disposing the wastes
being generated daily by the ever-increasing activities of the sawmills
(Babayemi and Dauda, 2010).
Industry, electric power producers, and commercial
businesses use most of the wood and wood waste fuel consumed in Nigeria. The
wood and paper products business uses wood waste to generate steam and power,
which saves money by reducing the amount of other fuels and electricity needed.
To reduce sulfur dioxide emissions, certain coal-fired power stations burn wood
chips.
Sawmill is a key wood processing business that has made substantial
contributions to the economic growth of not only Nigeria, but the globe at
large, since its inception. The sawmill is currently a significant employer of
labor in the nations where it operates. Sawmill industries contribute
approximately 2 % of the world's total Gross Domestic Product (GDP) (World
Bank, 2006). In developing nations such as Nigeria, the sawmill industry
currently contributes around 2.7 % of Gross Domestic Product (G.D.P) and is
growing at a quicker rate (Awake, 2003). Sawmill has continued to serve other
wood-based sectors both locally and globally.
Thus, sawmills are an
essential economic force for growth, particularly in developing nations with
abundant forest resources, such as Nigeria. The majority of Nigeria's sawmill
industry are located in the country's wood-producing rain forest areas. Lagos,
Ekiti, Osun, Cross River, Ondo, Oyo, Imo, Edo, Delta, and Ogun State have the
highest concentration of sawmills, accounting for more than 90% of the
country's saw milling activities (RMRDC, 2003).
Sawmills, by definition,
generate a lot of waste: sawdust, wood off-cuts, wood barks, plain shavings,
wood rejections, and so on. In the absence of adequate disposal techniques,
these wastes are burned in the open air, deposited along stream and river
banks, or left to decay in any available place (Popoola et al., 2013). Sambo (2009) estimates that the quantity of sawdust
produced in Nigeria is about 1.8 million tonnes per annum, While Francescato et al. (2008) reports that the
corresponding figure for wood waste is 5.2 million. As the demand for wood and
its products grows, so, too, does the volume of waste generated. Therefore, one
of the environmental problems facing cities and towns today is the proper
disposal of the wastes being generated daily by the ever-increasing activities
of the sawmills (Babayemi and Dauda, 2010).
Meanwhile, the huge quantity of wood
waste produced (by sawmills and other wood industries) in and around Nigerian
cities and towns poses environmental and health challenges. Wood wastes can
however be developed directly as fuel by public and private power facilities in
dedicated power systems. Utilizing biomass waste as an energy source (fuel)
converts environmentally detrimental materials (such as residues from
agricultural lands, forests and wood processing industries) into fuel
materials. Considering emerging global trends, the current desire for
mitigating climatic changes, and the push to empower consumers in both
developing and developed worlds magnify the need for a less-centralized
generation, transmission and distribution of energy (Umar, 2004). If developed
well, studies and projections have shown that several Renewable Energy
Technologies (RET) would be in a position to compete with fossil fuels by 2025.
Moreover, a better and well-managed energy investment and local production of
RET in developing countries, coupled with an enhanced focus on Research and
Development (R&D) for RET and energy efficiency are highly essential if
this goal is to be achieved (Olesen and Kvetay, 2001). In general terms,
renewable energy resources, if fully harnessed, could serve as a strategy of
reducing poverty significantly, as well as enhancing sustainable development in
Nigeria (Nnaji et al., 2010).
The huge quantity of wood wastes
generated by sawmills and other wood industries in and around Nigerian pose
environmental and health challenges. These wastes can however be exploited directly
as fuel by public and private power facilities in dedicated power systems.
Utilizing biomass waste as an energy source (fuel) converts environmentally
detrimental materials (such as residues from agricultural lands, forests and
wood processing industries) into fuel materials. Considering emerging global
trends, the current desire for mitigating climatic changes, and the push to
empower consumers in both developing and developed worlds magnify the need for
a less-centralized generation, transmission and distribution of energy (Umar,
2004). If developed well, studies and projections have shown that several
Renewable Energy Technologies (RET) would be in a position to compete with
fossil fuels by 2025.
Moreover, a better and well-managed
energy investment and local production of RET in developing countries, coupled
with an enhanced focus on Research and Development(R & D) for RET and
energy efficiency are highly essential if this goal is to be achieved (Olesen
and Kvetay, 2001). Forests in Nigeria are made up of many forest resources with
timber as the major interest to Nigerian forest consumers (Adewole and Onilude,
2011; Rotowa et al., 2017). Wood
gathered for both residential and commercial use from natural and conserved
areas accounts for a significant portion of forestry in Nigeria. Sawmilling is
described as the process of transforming round wood from the forest into lumber
through the use of various processing devices (Kukogho et al., 2011; Izekor et al.,
2016). Over the last few decades, the sawmilling business in Nigeria has played
an essential part in the wood products sectors (Ogunwusi and Jolaoso, 2012).
The forestry industry is seen as underperforming in
terms of resource management and the competitive wood processing industry (Ogle
and Nhantumbo, 2006). The high ratio of forest loss in Africa is a major
problem. Between 1990 and 2000, the continent lost about 5.2 million ha of
forest, accounting for about 56 percent of the global reduction in forest
cover. Although other natural resources have been utilized, the rate of timber
collection has increased dramatically since the turn of the century. In central
and west Africa, the tropical rain forest has been an imperative foundation of
timber, and other valuable non-timber product (Keegan, 2011). The increased
demand of timber and method of extraction has caused severe depletion of forest
resources. Since 1990, an estimated 420 million hectares of forest have been
destroyed due to deforestation. In the period 2010-2020, Africa had the largest
yearly rate of net forest loss, at 3.9 million ha (FAO, 2020). The
ever-increasing demand for wood-based products, combined with the continuous
harvesting of logs for various domestic and industrial applications, has
resulted in a reduction in the forms and sizes of logs available for conversion
in forests, resulting in smaller sizes of marketable lumber generated by
sawmills. To address this rising demand, appropriate sawmilling procedures that
promote a high lumber recovery rate are required (Olufemi et al., 2012). Numerous research projects have thus been undertaken
with the goal of boosting lumber recovery efficiency during log conversion in
order to properly utilize this very scarce forest resource. Lumber recovery
ratio refers to the volume of lumber generated during conversion in relation to
the volume of log converted; and is widely used as a strategy of assessing the
efficiency of sawmills. In Nigeria, the lumber recovery efficiencies of
sawmills have been estimated to range between 45–50 %, with 50–55 % of wastes
generated in form of sawdust, edgings, slabs and shavings (Egbewole et al., 2011; Omoniyi and Fatoki, 2013).
The recovery efficiency has become increasingly significant with increasing
logs price and transportation cost, and decreasing volume of standing timbers.
Subsequently, the technological improvement of wood products industries has
steadily increased the recovery efficiency. The lumber recovery efficiency of
sawmill may be predisposed by many variables such as unconventional way of log
conversion, sawing machines, log diameter and length (In Yang et al., 2007). The loss of timber
resources beyond sustainable limit is a serious issue in Nigeria. Consequently,
the need for a study on assessment of wood wastes for domestic energy
utilization in sawmills of Abia State, Nigeria so as to reduce the severe
degradation and wastage of forest resources.
1.2 STATEMENT OF THE PROBLEM
Nigeria's
energy supply is primarily fossil-based. The unequal distribution of oil
wealth, which resulted to agitation for self-determination and resource
control, has contributed to the sabotage of oil installations. However, a
recent study has shown that combined with the use of micro-grids, the 1.8
million tonnes per year of wood waste produced by the lumber industries in
Nigeria could help ease the situation with the supply of 1.3 TWh of
electricity. Nigeria
is the world's sixth largest producer of oil, with exports of crude forming the
backbone of its economy. The Niger Delta region is home to most of the Nigerian
oil wells, but the area has failed so far to enjoy the benefits of such huge
revenues.
Most basic amenities are
nowhere to be found when compared with other parts of the country. The
situation has led to agitation, with oil pipelines being vandalized, as well as
sabotage and abductions. The disruption caused has led to many power stations
losing their supply of natural gas, dramatically decreasing and even completely
halting power generation.
Considering the
non-renewable nature of fossil energy, coupled with never ending agitation for
resource control in the Niger Delta regions, the solution to power problems in
Nigeria may be a new renewable option.
Biomass resources such as
municipal solid waste and animal waste, agricultural crops and residues, as
well as forestry resources, are common in Nigeria. Given that they are widely
available, especially wood waste, there is a large potential for their use in
producing biofuel.
1.3 OBJECTIVES OF STUDY
The
aim of the study is to determine of wood species
utilized in selected sawmills, waste volumes and preference for domestic energy
in Abia State, Nigeria.
The specific objectives of
the study are:
i.
to identify the processed wood species and determine their abundance.
ii.
to determine the number and volume of logs in the study area
iii.
to determine the number and volume of produced timber in the study
areas.
iv.
to determine the volume of wood wastes generated in the timber sawmills.
v.
to determine the conversion efficiency of the various mills.
vi.
to determine the preference status of the wood wastes of the tree
species for domestic energy.
1.4 SIGNIFICANCE OF THE STUDY
Sawmills, by their
very nature, generate considerable amount of wood wastes - sawdust, off-cuts,
wood barks, plain shavings and rejects.
Estimates of the amount of sawdust generated in Nigeria range from
around 1.8 million tonnes to 5.2 million tonnes per annum (Sambo, 2009). As the
demand for wood and its products increases, the bulk of wastes generate
increases too. Therefore, one of the environmental problems facing cities and
towns today is the proper disposal of wastes generated by these sawmills (Aina,
2006).
In the absence of
appropriate disposal procedures, these wastes are burnt in the open air, dumped
along the bank of streams and rivers or left on any available space to rot. The
absence of good management strategies of these wood wastes causes improper
disposal into the environment resulting to environmental problems. Abandonment
of wood wastes at the mills causes aesthetic destruction while neglect along
the road side destroys air quality. This practice could cause respiratory
problem in human beings (UNESCO, 2000). The open air combustion of saw dust
often causes air pollution with the release of Carbondioxide (CO2),
smoke, Nitrodioxode (NO2) etc and loss of potentially useful energy
into the environment. Many sawmills especially those located at the banks of
rivers particularly in Ogun, Lagos, Edo, Delta, Bayelsa, and Rivers states
often dispose waste wood into water bodies. Arimoro et al. (2007) reported that sawn wood waste negatively affect
aquatic life of such rivers.
Meanwhile, the capacity of
wood waste produced in and around Nigeria cities and towns poses environmental
and health challenges. It can however be exploited straightly as fuel by public
and private power facilities; moreso that the rapid demand for energy due to
increasing population and technology advancement has led to sharp inflation of
fuels’ prices in Nigeria. This has stimulated the need to search for
alternatives to the cost and dwindling fossil fuel deposits. Among the energy
alternative that could be examined are renewable sources of energy from woody
biomass which is considered to offer a more environmental friendly and cheaper
solution to the energy supply problem in the country.
Furthermore, due to
inadequate management and utilization methods of these renewable energy
sources, they are usually discarded into the environment with attendant
environmental hazards. Also, the practices employed in the utilization and
disposal of wood waste contradict sustainable solid waste management which
encourages the efficient utilization of materials in a manner that reduces
amount of waste production and the management of waste in a way that meets the
economic, social and environmental goals of sustainable development (Pianosi,
2012).
According to International Institute for Sustainable
Development (IISD) (2016), sustainable development is a development that satisfies
the need of the present generation without jeopardizing the ability of future
generations to meet their needs. Thus, to guarantee sustainable and economic
management of wood waste produced in Abia State, Nigeria, wood waste must cease
to be regarded simply as a disposal material, but rather as a valuable economic
resource, with prospects for energy generation. This study seeks to assess the
utilization potentials of wood wastes produced from sawmills in Abia State for
energy. The study will particularly evaluate the availability, quantity,
frequency and economics of wood waste (sawdust) generated from sawmills in Abia
State.
1.5 SCOPE OF THE STUDY
The study was carried out at sawmills
in Aba North, Umuahia North
and Bende Local Government Areas of Abia State, Nigeria. Extensive
questionnaire administration will also involve respondents from the study areas
of the State.
The parameters studied include the
abundance of the processed wood species, number and volume of converted logs,
number and volume of produced lumber, amount of generated wood wastes from the
mills, conversion efficiency of the mills and the comparison of the use of wood
wastes of different species for energy. The wood wastes to be examined in this
study is sawdust.
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