International Journal of Scientific & Engineering Research, Volume 6, Issue 1, January-2015 1255
ISSN 2229-5518
IJSER © 2015
http://www.ijser.org
The Effect of Temperature on the Rate of
Digestion and Biogas Production using
Cow Dung, Cow Pea, Cassava Peeling.
Ukpai, P. A., Agbo, P. E and Nnabuchi, M. N.
Department of Industrial Physics, Ebonyi State University Abakaliki.
E-mail: ukpaipatricia@gmail.com
ABSTRACT: Biogas production from 3-batch biogas plant containing different ratio of mixture of Cow dung,
Cassava and cowpea peeling was studied for a period of one month. The ambient and slurry temperature were
taken into consideration. Different regression models were used to describe the biogas cumulative production
from the plants and the effect of temperature on the volume of gas produced. The study showed that for increase
in gas production, a temperature of between 32-40OC is favourable and optimum. Our result revealed that gas
production is dependent on temperature of operation of the digester and the nature of waste used.
Keywords: Temperature, Slurry, Cassava peeling, Cow dung,Cowpea peeling, Biogas Plant
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I NTRODUCTI ON
The current energy demand and consumer’s buying capacity calls for alternative energy
sources. Biogas technology is one of the reliable alternative energy source. The
development of biogas has helped in reducing the rate of deforestation; improve health and
sanitation in rural areas, while the residue which is used as fertilizer has increase agricultural
production [1]. Gas produced by the digester in an anaerobic decomposition is called biogas;
Biogas is methane–rich gas that is produced from the anaerobic digestion of cellulosic
matter. It is denser than air and has a density of 1.2kg/L at atmospheric pressure. This gas
is produced from a three-phase process namely; hydrolysis, acid forming and methane
forming phase. This gas is composed of methane(50-70)%, carbon dioxide(30-40)% and
traces of other gases such as carbon (11) oxide(Co), Nitrogen gas(N
2
), Water
vapour(H
2
O
(g)
), Ammonia(NH
3
) and hydrogen sulphide(H
2
S), [8]. Temperature is one of the
most factors that affect the production of gas, it has been observed that the ideal
temperature for anaerobic digestion is 35
o
C. As the temperature increases, some bacteria
begin to die and biogas production decreases. It is also a waste management technique
because the anaerobic treatment process eliminates the harmful micro – organisms [15]. It
is a cheap source of energy because the feedstock is usually waste materials and ensures
energy independence; as a unit can meet the needs of a family or community. Gas yield
from the digester may not be steady which therefore makes it unreliable thereby
necessitating storage. Another advantage of methane is that unlike other fuels, it does not
give off poisonous carbon monoxide when burnt, so it is safer to use in the home than other
gases for cooking and heating [7]. Due to the changes in temperature there is low pressure
gas production system and as such cannot be bottled for use outside the site of production
thereby restricting the technology only to the site of production [4]. Temperature is an
important parameter in biogas production, due to its effect on the enzymatic activities of the
micro–organism responsible for the bioconversion of substrates into gas. The operating
temperature ranges of particular bacterial types are at the psychophilic (below 20
0
C) ,
mesophilic (20
0
C – 40
0
C) and thermophilic (40
0
C - 65
0
C) temperature. At a physchophilic
temperature range, the Bioconversion is slow and incomplete, and requires longer retention
time. For the case of mesophilic, the temperature corresponds to the ambient temperature
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