Animal Production Research Advances, 5(3): 198-201, 2009
www.tapasinstitute.org/journals/apra
©
Tapas Institute of Scientific Research and Development, 2009
DETERMINATION OF THE BIOGAS YIELDING POTENTIALS OF CATTLE
DUNG AND CATTLE EGRET DROPPING
U. A. Birnin-Yauri1,2, F. A. Atiku2, A. U. Itodo2, M. M. Ambursa2, A. A. Gebe2 and M. M. Goronyo
1
Department of Pure and Applied Chemistry, Usmanu Danfodiyo University, Sokoto
2
Department of Pure and Applied Chemistry, Kebbi State University of Science and Technology,
Aliero, Nigeria
Corresponding author: U. A. Birnin-Yauri; E-mail: bubakaabu@yahoo.com
ABSTRACT
Anaerobic fermentation of cattle dung and cattle egret droppings was carried out to determine their
biogas yielding capacities. Two digesters labeled A and B were used. Digester A contained 50 g
cattle dung and 500 ml of water and digester B contained 50 g cattle egret dropping and 500 ml of
water (i.e. 0.1 gcm-3 slurry concentration). The retention time was 10 weeks (70 days). The
fermentation temperature varied from 27 to 330C. The pH also varied from 6.8 to 8.2. The total
biogas yield (TBY) over the 70 days was 6.779 liters for digester A and 4.494 liters for digester B.
Analyses of physicochemical properties that had bearing on the digesters biogas production
capacity was also carried out. The N., P and K analysis on the samples showed greater contents in
undigested sample of A and contrarily, greater contents in digested sample of B.
Keywords: Cattle dung, egret droppings, biogas yield, digester
INTRODUCTION
Fossil fuels such as firewood, petroleum, coal and natural gas have been used for decades to meet
the energy requirement of man. Fossil fuels are however associated with negative environmental
hazards such as flooding, erosion, desertification through deforestation, reduced biodiversity and
global warming (Munack et al., 2001). Again, these conventional sources of energy supply
otherwise known as non-renewable energy sources are threatening to run-out in the foreseeable
future (Sambo, 1981). It has been widely reported that not less than ten major oil fields from the
20 largest world oil producers are already experiencing decline in oil reserves. A recent data
published revealed that a total of 29 major world oil producing countries are already experiencing
declining oil reserves from year 2005 to 2007 (EIA, 2007). However, Nigeria’s oil reserves could dry
up in the next 50 years.
Many have attributed the decline in Nigerian production to violence by the armed militant groups in
the Niger Delta reion that habours most of the Nigerian oil reserves (Carmen, 2008). This has
caused the country’s oil output to shrink dramatically over the last three years (Sabon birnin,
2008). There is therefore, the need to search for alternative energy sources to supplement the
fossil fuels for the future betterment of the Nigerian economy. Thus, a recent development
emerged providing a clean energy resource in the area of renewable energy.
Research studies have reported investigations into the biogas yielding potentials of cattle dung on
which many works have been done (Smith et al., 1979; Fernando and Dangoggo, 1986; Garba,
and Sambo, 1992; Garba, 1996; Abubakar, 1999; Dangoggo, 2000) and cattle egret (Bubulcus ibis)
dropping.
Biogas is a low cost form of secondary biofuel derived from renewable resources such as animal
wastes, plants and human wastes. The gas is generated by the anaerobic fermentation of biomass.
The energy generated is environmentally friendly and could be used for heating, cooking and
electricity production (Birnin-Yauri, 2005). The anaerobic process of generating biogas consists of
three distinct stages namely hydrolysis, acetogenesis and methanogesis. Hydrolysis involves
breaking down of large macromolecules of sugar, amino acid and fatty acid by bacteria under
anaerobic condition. Acetogenesis involves conversion of sugar into short-chain acid (mainly acetic
acid) by acetogenic bacteria and methanogenesis is carried out by methanogenic bacteria that
convert the acid into methane (Farina et al., 1988; Markl, 2001).
In this study, the anaerobic fermentation of cattle dung and cattle egret droppings was carried out
to determine their biogas yielding capacities.
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Birnin-Yauri et al.: the biogas yielding potentials of cattle dung and egret dropping
MATERIALS AND METHODS
Two kilograms each of fresh samples of cattle dung and egret dropping were collected from Birnin
– Yauri, Kebbi State, Nigeria. The samples were sun dried with intermittent mixing for a week.
Using pestle and mortar, the samples were reduced to fine powder and stored in separate
polythene bags. Fifty gram each of the powdered samples was weighed and kept in a separate
containers labeled A and B. Slurry samples of A and B were thereafter prepared by mixing 50 g of
each sample with 500 ml of water to give a 0.10 gcm-3 slurry concentration. After 30 minutes, the
pH of each slurry was measured and recorded.
Digesters were prepared according to the method previously described by Birnin-Yauri (2005). For
the digestion proper, the methods reported by Dangoggo (2000) and Garba and Sambo (1992)
were adopted. Two clean cylindrical tins each having 600 cm3 capacity and labeled A and B. In the
middle of each lid, a hole was perforated and one terminal end of a P.V.C rubber tube (3mm in
diameter and 30 cm long) inserted in this hole and glued with gum. The corresponding slurries
were transferred into the labeled digesters A and B such that A contained cattle dung and B
contained egret dropping. The lid of each digester was replaced and glued airtight. Two retort
stands were arranged and one water trough filled with tap water was placed to each retort stand.
The pH of each slurry was recorded and the digesters sealed with gum to ensure that the digesters
were leak proof and air tight. The biogas yield was monitored at 24 hours intervals for for a period
of 70 days (7 weeks) after which it was terminated. The average ambient temperature over the
period was 32±2oC (Amamatu, 1995).
The proximate chemical compositions of the digested and undigested cattle dung and egret
dropping were determined according to the methods of AOAC (1990). The parameters determined
included, percentage moisture content (MC), percentage ash content (AC), percentage volatile
matter (vm) and carbon content (cc), percentage total solid (TS) and NPK analysis. In the
determining the nitrogen content of both the digested and undigested samples, the Kjeldahl
method was used (AOAC, 1990). Likewise, the principles of spectrophotometry and flame
photometry were employed in determining the contents of phosphorus and potassium respectively.
RESULTS AND DISCUSSION
The results on biogas produced and all the analysis conducted on the physical characteristics and
NPK contents of the samples are summarized in tables 1 and 2. Gas production commenced 3
hours after the setup was completed on the very first day. Digester A recorded 0.015 liters while B
recorded 0.004 liters. When the process was terminated after 7 weeks, digester A recorded the
highest gas yield (6.779 liters), while B recorded a total of 4.494 liters. Hence, cattle dung is a
better potential substrate than egret dropping as also observed in previous works (Smith et al.,
1979; Abubakar 1999; Birnin-Yauri, 2005).
Table 1: Weekly cumulative biogas produced in 70 days (10 weeks)
Week
Digester A (liters)
Digester B (liters)
1
2
3
4
5
6
7
8
9
10
Total
0.52
0.446
0.576
0.077
1.106
1.741
1.69
0.37
0.17
0.083
6.779
1.39
2.198
0.74
0.022
0.099
0.04
0.00
0.05
0.00
0.00
4.494
It could be seen from table 2, the moisture contents of the undigested samples is less than the
digested ones in A with a range of 1.12% only. While the range is 2.75% in B. Thus, in terms of
moisture contents, the Biogas production capacity of the two digesters should not differ much.
Moreover, the result of ash contents shows that the ash contents increases after anaerobic
digestion as can be seen in table 2, the ash contents for the digested samples is greater than the
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Birnin-Yauri et al.: the biogas yielding potentials of cattle dung and egret dropping
undigested ones. This could be as a result of anaerobic digestion which draws out carbon,
hydrogen and oxygen out of the substrates (Dangoggo, 2000; Birnin-Yauri, 2005).
Table 2: Result on physical characteristics and N.P.K contents
S/no
Parameter
Au
Ad
Bu
Bd
1
2
3
4
5
6
7
8
9
Moisture content
Ash content
volatile matter
Total solid
carbon content
Nitrogen
Phosphorus
Potassium
pH
4.98
9.33
85.69
95.02
49.70
1.12
0.25
10.28
7.5
6.10
32.20
61.70
93.90
35.79
1.05
0.59
5.60
8.2
2.60
10.30
87.1
97.4
50.52
1.65
0.40
15.00
6.8
5.35
27.00
67.65
94.65
39.24
1.72
0.61
10.28
7.0
Key: u = undigested sample d = digested sample.
However, the higher the volatile matter of a sample, the higher its biogas production capacity
(Garba, and Sambo, 1992). The result in table 2 shows that the volatile mater contents for the
undigested sample of cattle dung is greater than that of egret dropping. Thus produced more
biogas as can be seen from the biogas produced by cattle dung. The pH values for the undigested
and digested samples shown in table 2 above varied from 6.8 in B to 7.5 in A. But, the optimum pH
range for production of biogas is between 7.0 and 9.0, although gas production is satisfactory
between 6.8 and 7.6 (Garba, 1996).
The result of the N.P.K analysis shows that undigested sample of cattle dung contained high
composition than the digested one while the digested sample of egret dropping contained high
content than the undigested as can be seen in table 2. Thus, undigested sample of cattle dung is a
better fertilizer than digested sample of cattle dung and the digested sample of cattle egret
dropping is a better fertilizer than the undigested sample.
CONCLUSION AND RECOMMENDATION
The cattle dung and cattle egret dropping produced significantly large quantity of biogas, with
cattle dung being the most potential viable substrate for biogas production. The increase in the ash
content after digestion proved that biogas was generated and the calculated moisture contents
gave ranges which are favorable for optimum gas yield. The undigested cattle dung and digested
egret dropping are important fertilizers for farm applications.
The biogas yield of the cow dung and cattle egret dropping is enough to provide energy for
heating, cooking and even more so electricity generation by improving the technology for a large
scale production. The substrates also provide potential fertilizers for soil improvement and
promotion of plant growth.
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