UTILIZATION OF CASSAVA PROCESSING WASTE AS A VIABLE AND SUSTAINABLE STRATEGY FOR
MEETING CASSAVA PROCESSING ENERGY NEEDS: CASE STUDY FROM IBADAN CITY, NIGERIA
A.O. Coker*1 C.G. Achi1 and M.K.C. Sridhar2
1 Department of Civil Engineering, Faculty of Technology, University of Ibadan
2 Department of Environmental Health Sciences, Faculty of Public Health, University of Ibadan
*Corresponding author: [email protected]
Abstract
Improper management of solid wastes and problems of pollution have been the bane of life of
many urban community residents in Nigeria. Waste generation is an inevitable fact of living.
With increase in population and industrial activities come the increase in waste generation. One
of such industries is the agro-food processing industries. In Nigeria, cassava is a food item
predominantly processed, being a starchy staple food crop which can be converted into myriads
of edible and industrial raw materials.
Recognising the importance of cassava food crop and its growing production rate in Ibadan,
south-western Nigeria, this study focused on evaluating the cassava production activities in six
selected cassava processing sites in the city. The cassava roots delivery rates, the waste
generation rates, waste composition, cassava processing energy needs and the attitudes of the
people towards cassava waste management were some of the issues investigated.
Results showed that the percentage and composition of solid waste (Peels and bagasse) and
liquid waste generated during cassava processing depends on the nature of the final product
and this varied also according to market demand of products. Fufu (cooked cassava paste after
fermentation) produced more liquid waste and baggase than cassava starch and garri (toasted
cassava granules). Fufu was produced more frequently than other products due to its much-
reduced production cost and high market demand as compared to other products. It was found
out that all of the solid wastes produced were organic in nature and can be recycled, recovered
and reused. Between 25 – 30% of the cassava peels and bagasse were utilized as feedstock for
livestock (goat and pigs) while the remaining 70 – 75% of cassava peels, bagasse and waste
effluent were discharged indiscriminately into nearby bushes and water bodies. The only source
of energy for processing fufu and garri is firewood which is usually obtained from cutting down
forest trees.
The study came up with a low-cost, sustainable strategy to provide an alternative renewable
energy source to firewood which will also ensure a proper solid waste management for the
cassava processing industries.
Keywords: Cassava waste, rural regions, sustainable development, renewable energy, Nigeria
1.0 Introduction
The provision of food to meet the world’s growing population has become a global concern in
recent times. Researchers and policy makers have explored and continued to exploit various
ways of providing the best crop-growing conditions and also the most efficient agricultural
food harvesting and processing techniques to meet this growing need for food. Fertile soils and
conducive crop-growing climate are some of the natural factors that promote food production.
Most developing Sub Saharan African countries are endowed with these natural factors and as
such are known to support the growth and production of so many food crops.
One of such crops is Cassava (Manihot esculenta), a starchy staple food crop, which is regarded
as a primary food security crop in Africa due to its resistance to drought and diseases. Cassava
provides a reliable and inexpensive source of carbohydrate for people in Sub-Saharan Africa,
especially in Nigeria where its production, processing and consumption is most predominant
and significant on a global scale (Westby, 2008)
Cassava roots can be processed into myriads of food items and raw materials for industries.
During cassava conversion processes for food such as garri (toasted cassava granules) or fufu
(cooked cassava paste after fermentation), energy and water needs are considered to be vital.
In rural regions of most developing countries, firewoods are usually employed as a heat energy
source for toasting garri and cooking fufu. The sole dependence on firewood for cooking and
toasting cassava products has consistently put pressure on the use of forest trees. This
dependence promotes felling of trees to meet up with the increasing cassava processing rate
and energy demand for cassava production and processing and consequently this practice can
be linked to deforestation.
Besides energy demand and water consumption, waste generation is a key environmental issue
in all food processing industries (EC, 2006) including cassava processing industries. The
continuous growth and thriving of cassava processing businesses in most developing sub-
Saharan African countries has resulted in the generation of large amounts of cassava processing
residues. Three main types of residues are generated during the industrial processing of
cassava: peels, bagasse (solid) and wastewater (liquid). These wastes are poor in protein
content, but are carbohydrate-rich residues and are generated in large amounts during the
production of ‘garri’ and cassava flour (which generates more solid residues) and starch (which
generates more liquid residues) from the tubers. The cost of treatment and disposal of these
wastes constitute a huge financial burden to the cassava processing industries in rural regions
of developing countries. As a result of this challenge, the rural cassava processors resort to
indiscriminate disposal of cassava processing wastes into the environment and water bodies
without any form of treatment. These wastes are known to have high levels of Chemical
Oxygen Demand, Biochemical Oxygen Demand and are often laden with suspended solids that
are considered to be toxic (Plevin and Donnelly, 2004, Barros et al, 2012). The disposal of
these toxic wastes without prior treatment leads to the alteration of the receiving water bodies
and ecological systems.
From the foregoing, there is a need for a better management and utilization of these waste
residues. Due to their rich organic nature, cassava residues can serve as ideal substrate for
microbial processes in the production of different products. Attempts have been made by
various researchers to produce products such as organic acid, flavour and aroma compounds,
methane and hydrogen gas, enzymes, ethanol, lactic acid, bio surfactant,
polyhydroxyalkanoate, essential oils, xathan gum and fertilizer from cassava bagasse, peels
and wastewater (Siddhartha et al, 2012). The use of cassava residues as feedstock for methane
(bioenergy) production could be a viable alternative to firewood.
It is against this backdrop that this study seeks to explore the potentials for utilizing an
integrated cassava production and waste management strategy, through cassava solid waste
reuse and bioenergy recovery, targeted at the cassava processors in the resource-limited sub-
Saharan African region, where cassava production is predominant.
2.0 Potential of producing bio-energy from cassava wastes and other biomasses in
Nigeria
2.1. Cassava roots production in Africa and Nigeria: some basic statistics
According to FAO (2006) estimates, world annual production of cassava roots stood at
approximately 226 million Metric Tonnes (MT), out of which 54% (122 million MT) are
produced in Africa. In this specific context, West African countries produce the majority of
cassava roots: 63 million MT, equal to 52% of the total African cassava production, followed
by Eastern Africa countries with a production of approximately 31 million MT (or 25% of
Africa’s total).
As shown in the table below, with a yearly production of approximately 45 million MT, equal
to 37% of the total cassava produced in Africa, Nigeria is the first African largest producer.
Table 1: Key Figures on Cassava Production in Africa
Cassava Production in the World
Geographic area MT %
World 226,337,396 100
Africa 122,088,128 54
Asia 67,011,365 27
Latin America & Caribean 37,041,521 16
Others 196,382 1
Cassava Production in Africa
Geographic area MT %
Africa 122,088,128 100
Western Africa 63,261,251 52
Eastern Africa 30,757,886 25
Middle Africa 28,057,653 23
Northern Africa 11,338 0
Major Cassava Production Countries in WCA
Country MT %
Africa 122,088,128 100
Nigeria 45, 721,000 37
DRC 14,974,470 12
Ghana 9,638,000 8
Benin 2,524,234 2
Ivory Coast 2,200,000 2
Congo 1,000,000 1
Source: FAOStat 2006
In Nigeria, the cassava-growing belt falls within three agro-ecological zones of the southeast,
southwest and the central areas. (FAO, 2005).
In most part of these zones, cassava is traditionally cultivated by smallholder farmers; in the same
way, its processing is usually done by small-scale processing units, scattered all over cassava
production areas.
In Ibadan (South-western Nigeria) for instance, as elsewhere in Nigeria, small farmers (mainly
males) are mainly responsible for growing cassava, which is a year-round crop.
Traditionally, the bulk of cassava products are processed by women at village level, working
independently or organised into informal groups or co-operatives. At this level of production, the
major products are garri, fufu, starch and lafun (dried cassava meal after fermentation)
Plate 1: Women Processing Cassava at Moniya, Ibadan
Cassava conversion processes
The flow charts below (figures 1 and 2) depict the processes involved in the production of Garri
or attieke, and starch respectively.
Fig 1 Flow chart of garri and attieke processing
Source FAO 2001
Fig 2 Flow chart for the conversion of Cassava to starch
Source FAO 2001
Solid waste is usually generated by all forms of cassava processing. For instance, solid waste
from cassava starch processing is divided into three categories: (i) Peelings from initial
processing, (ii) Fibrous by-products from crushing and sieving (pulp waste) and (iii) Starch
residues after starch settling. The weight of solid waste produced is usually between 10 –
25 % of the total weight of cassava root before peeling.
Renewable Energy Production from cassava wastes
Bio-methanation (biogas production) is a renewable energy technology where organic
materials e.g. animal manure, night soil, agricultural residues, Municipal Solid Waste
landfills and industrial effluents, are biologically fermented in the absence of oxygen to
produce flammable gas consisting predominantly methane (CH4) and carbon dioxide (CO2).
(Sridhar et al 2003). Combustible gases produced can be stored and turned into energy by
means of an electrical generator.
Literature is replete with various studies on the conversion of cassava peels mixed with other
substrates to generate biogas. Although biogas generation rates vary according to the kind of
substrate used and the ratio of mixture. For instance, Ofoefula et al, (2009) investigated
biogas production from blends of cassava peels mixed with some animal waste. The result
showed that the low biogas yield and slow onset of gas production / flammability of digested
cassava peels can be enhanced significantly when combined with animal wastes. The blend
with cow dung and poultry droppings had the fastest onset of gas flammability while that
with swine dung had the highest cumulative volume of gas production. Hence, he concluded
that cassava peels which is considered a nuisance can be converted to a useful source of
energy by combining it with these or any other animal wastes.
In a documented research (Eze, 2010) it has been demonstrated that anaerobic fermentation
is an environmentally friendly technology that could be used to generate biogas from cassava
peels. (Adelekan and Bamgboye, 2009) established the possibility of generating biogas from
cassava peels mixed in selected ratios with major livestock wastes. This was demonstrated
using a mix of cassava peels with poultry, piggery and cattle waste at different ratios, the mix
with piggery waste at the ratio of 1:1 produced the highest biogas yield.
Cuzin et al, (1992a).carried out anaerobic digestion of raw cassava peels using a 128 L plug
flow digester. The results showed that a biogas yield of 0.661 m3 per l kg volatile solids (VS)
was obtained. Energy-saving calculations showed that a bioreactor of 88 m3 is sufficient to
produce the methane necessary for drying one ton of cassava meal.
3.0 .Material and methods
Study Locations
Six cassava processing sites were visited in Ibadan, South western Nigeria to assess their
cassava processing operations. The sites are as follows: Moniya, Eleyele 1, Eleyele 2, Ojoo,
Agbowo, Egbeda.
Study Design
The methodology adopted to carry out this study includes the implementation of:
(i) field visits in Ibadan for collecting primary and secondary data from small and
medium-sized cassava industries,
(ii) face-to-face meetings with local cassava producers and processors, and assessment
of current practices
(iii) Assessment of daily cassava delivery and production rates
(iv) Characterization of cassava processing waste
The sites were randomly selected within Ibadan Metropolis. This was done so as to capture the
true picture of the current cassava processing scenario in Ibadan.
During data collection from the sites the following methods were employed.
1.) Key Informant Interview
2.) Direct Personal Observation
The following data were collected and used to make comparison as regards management and
waste disposal practices
1. Name/ Location of the cassava processing site
2. Operations and major cassava products
3. Challenges faced by the workers
4. Number of the workers and Scale of the processing system
5. Cassava processing rate
6. The volume of cassava wastewater effluent produced per unit Kg of cassava
7. The weight of solid waste produced per unit Kg of cassava
8. The amount and volume of solid and liquid waste produced respectively in a cassava
processing site
9. Comparative cost analysis of processing garri and fufu
10. Solid waste disposal method employed
The major products from cassava processing at these selected site are: Garri (Yoruba & Igbo
customary types), Fufu, and Lafun.
Conversion Processes
Cassava conversions processes involves all the processes employed to achieve a desired food
product from cassava tuber. The processes are as follows;
Garri Processing
Cassava tubers Peeling Washing Crushing Squeezing Sieving Frying
Fufu Processing
Cassava tubers Peeling Washing Fermentation Sifting Collection of sediments of
fermented cassava pulp and removal of excess water Cooking and subsequent pounding.
Lafun Processing
Cassava tubers Soak for a day for cyanide removal & slight fermentation peeling
Washing Crushing store in bags for 4days to allow for draining and further fermentation
Sun drying Crushing of dried crumbs into fine flour particles Prepare like semovita or
wheat meal.
Table 2 below shows the general practice recorded in six (6) randomly selected cassava
processing sites.
Assessment of the amount of waste produced
For the purpose of this experiment, two heaps were purchased so as to determine unit weight
of cassava and peels and also quantity of water used for cassava conversion processes into garri
and fufu.
Cost of one heap of cassava as measured by the farmers is 660 Naira (3.5 USD)
During the processing of cassava tubers >10% of the tubers result in peelings whereas 3.25%
pulp is produced
These common features were recorded in all the sites visited.
1. All the sites were located close to a stream or flowing river. This usually serves as a
final disposal point for the waste effluents.
2. No strict measures have been put in place for the management of solid and waste
effluent and as such are disposed indiscriminately or dumped without check, the vast
majority of cassava peels resulting from the processing of this root is either
abandoned nearby the processing sites, used as land fill or burnt. Between 20-25%
of cassava peels and fibrous waste (bagasse), are sun dried (after having being
washed, to remove dirtiness, and drained) and fed to pigs and goats
3. All the cassava processors depend solely on firewood as the only source of energy
for cooking and toasting cassava products
Table 2: General cassava processing and waste disposal practice in six different sites in
Ibadan
Site/para
meters
Qu
an
tity
o
f C
ass
av
a
sup
pli
ed
da
ily
(to
nn
es)
No
. o
f W
ork
ers
Fin
al
Pro
du
ct
So
lid
w
ast
e (p
eels
) d
isp
osa
l p
ract
ice
Fib
rou
s w
ast
e d
isp
osa
l p
ract
ice
Ca
ssa
va
wa
stew
ate
r d
isp
osa
l p
ract
ice
Pro
xim
ity
to r
iver
/ s
trea
m
wei
gh
t o
f p
eels
pro
du
ced
da
ily
Vo
lum
e o
f ca
ssa
va
wa
stew
ate
r
pro
du
ced
da
ily
(li
tres
)
Eleyele 1
(Temidire
)
6 – 8 200 –
250
Garri,
fufu &
starch
Peels
sold to
goat
rearers,
10 – 25
%
disposed
as waste
Disposed
of as
waste in
nearby
bushes
Discharg
ed inside
drains
and
waterwa
ys
leading
to
nearby
streams
Appro
x
200met
ers
1464 –
2049kg
>5712
Eleyele 2
(Ologuner
u road,
besides
kappan
filling
station)
1 – 2 20 –
30
Garri
& fufu
“
“
“
100m 244 –
512 kg
>1428
Ojoo
Barracks
4 – 5 70 –
80
Garri
& fufu
“
“
“
150m 976 –
1281kg
>3570
Moniya 3 – 5 40 –
50
Garri,
fufu,
starch
and
lafun
“
“
“
200m 732 –
1281
kg
>3570
Agbowo 4 – 5 80 –
100
Fufu
only
“
“
“
50m 976 –
1281
kg
>3570
Egbeda/N
ew ife
Road
7 – 9 500 –
550
Garri
fufu,
lafun
and
starch
“
25 % is
used as
pig feed,
the rest
are
disposed
in
nearby
bushes
“
100m 1708 –
2305.
kg
>6426
Plate 2: Cassava waste dumpsite
Plate 3: Typical cassava waste dumpsite
Identified Challenges and Energy needs in a cassava processing industry
According to the observations made, garri is fried in shallow cast-iron pans, or in the more
traditional areas in earthenware pans, over an open wood fire. The sieved cassava mash is
spread thinly in the pan in 2-3kg batches. A piece of calabash is often used to press the mash
against the hot surface of the pan but it must be scraped quickly and stirred constantly to keep
the material moving to prevent it burning until frying is completed when it reaches a
temperature of 80° to 85°C. The rapid heating partially gelatinises the gari which is dried during
the operation of frying. The process takes 30-35 minutes, with the moisture content of the final
product reduced to about 18% (Muchnik and Vivier 1984, Bencini 1991). During the frying
process, women are forced to lean on the roasting pans to turn around gari, thus inhaling the
smoke from the wood fire.
Plate 4: Women frying garri and cooking fufu using firewood
Plate 5: Bundles of firewood waiting to be used
During roasting operations, the challenge of maintaining a uniform heating using firewood was
observed. Smouldering of firewood exposes workers (mostly women) to toxic fumes.The
major issue being the pressure put on forest tress amidst the growing cassava production rates,
sole dependence on forest woods and current issues and trends as regards the global climate
change and the need to discourage deforestation. These are some of the issues that have
necessitated the search for alternative heating methods
Conclusion
In Nigeria, the problem of poor infrastructural facilities, especially of energy has been
identified among many other challenges currently facing subsistence cassava farmers. In order
to prevent environmental impacts arising from the huge waste streams generated during
cassava processing, various agricultural wastes should be gathered and converted to useful
products.
Based on the current assessment of cassava production rate and waste generation in Ibadan
city, there is a significant potential of utilizing cassava waste as a sustainable energy source for
heating and electrification of the cassava processing environment. The daily supply of cassava
waste (< 1 tonne) is sufficient to maintain a steady supply of substrates for biogas production
to meet up with basic energy demands. Furthermore, use of cassava wastes as substrate for
producing biogas would decrease the potential damages to forests as it reduces the overall
amount of firewood employed to produce heat (for cooking or other purposes).
Apart from the already stated energy need for heating, the bioenergy recovered could be used
to power generators, which will be used to light up the processing environment during dark
working hours. It would also provide a more convenient means of supplying water to the
cassava processors from wells. Most cassava processing industries usually suffer from scarcity
of water supply. In most cases, when water is available in wells, the women involved in cassava
processing would have to go through the drudgery of drawing water from these deep wells.
A sustainable supply of energy from the conversion of cassava waste would go a long way in
meeting these demands and make life easier for the rural farmers.
Reference
Adelekan B.A and Bamgboye, A.I. (2009) Comparison of biogas productivity of cassava peels
mixed in selected ratios with major livestock waste types’ African Journal of
Agricultural Research Vol. 4 (7), pp. 571-577, July 2009
Barros, F.F.C, Ana Paula Dionísio, Júnio Cota Silva,and Gláucia Maria Pastore (2012)
Potential Uses of Cassava Wastewater in Biotechnological Processes. In Colleen
M. Pace. Ed Agriculture Issues and Policies: Cassava Farming, Uses and
Economic Impact. NOVA Science publishers Inc. New York. ISBN 978-1-61209-
655-1 (eBook) Chapter 2, page 33-54
Cuzin N, Farinet JL, Segretain C, Labat M (1992a). Methanogenic Fermentation of Cassava
peel using a pilot plug flow digester. Biores. Technol. 41: 259-264.
EC (2006) IPPC Reference Document on Best Available Techniques in the Food, Drink and
Milk Industries, Seville, European Commission, available at: http://ec.europa.eu/
environment/ippc/brefs/fdm_bref_0806.pdf (last visited January 2008).
Eze, J.I (2010) ‘Converting Cassava (Manihot spp) Waste from Gari Processing Industry to
Energy and Bio-Fertilizer’ Global Journal of Researches in Engineering Vol.10
Issue 4, September 2010 pp 113-117
FAO (2006) Food And Agriculture Organization Of The United Nations web page accessed at
http://faostat.fao.org/site/567/DesktopDefault.aspx?PageID=567#ancor
Ofoefule, A.U.and Uzodinma, E.O. (2009) Biogas production from blends of cassava
(Manihot utilissima) peels with some animal wastes. International Journal of
Physical Sciences Vol. 4 (7), pp. 398-402, July, 2009
Plevin R and Donnelly D (2004). Converting waste to energy and profit; tapioca starch power
in Thailand. Renewable Energy World. September-October Edition, 74-81.
Siddhartha G.V.A.O. Costa, Marcia Nitscke and Jonas Contiero (2012) Biotechnological
Potential of Cassava Residues: Peel, Bagasse and Wastewater. In Colleen M. Pace.
Ed Agriculture Issues and Policies: Cassava Farming, Uses and Economic Impact.
NOVA Science publishers Inc. New York. ISBN 978-1-62081-698-1 (eBook)
Chapter 4, page 79-98
Sridhar, M.K.C., Coker, A.O., Aikhomu, S.E., Ifedayo, A.O. and Itodo, I.P. (2003): Biogas
production from organic waste: Nigeria efforts. The Nigerian Field, Volume 68
part 2, page 112-123
Westby, A. (2008). Cassava Utilization, Storage and Small-scale Processing. In R. Hillock, J.
Thresh, & A. C. Bellotti, eds., Cassava Biology, Production and Utilization. CABI
Publishing
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