Ebonyi State is popularly known for rice production
(Abakaliki rice) in Nigeria and thus has large reserves of rice
husks from rice mills which are randomly and strategically
located in various towns. These large reserves of rice husks
are only utilised as cooking fuels (on a low scale) and source
of income for some poor rural dwellers who scavenge those
rice husk hills to earn a living. Waste from agricultural,
municipal, industrial and household are also common in the
study area but these wastes are not presently utilised in a
sustainable manner [8]. It has been shown that about 227,500
tons of fresh animal wastes is produced on daily basis in
Nigeria [9], implying that Nigeria can produce 6.8 million m3
gas/day since 1kg of fresh animal wastes yields up to 0.03 m3
gas. Ogwueleka [10] noted that the waste density of municipal
solid waste in Nigeria ranged from 280 to 370 kg/m3
with the
waste generation rates in the range 0.44 to 0.66 kg/capita/day.
The generation rate of solid waste in the capital cities of some
South-east States of Nigeria (Ebonyi and Imo) is in the range
9.580 to 9.74 x 10-3 m3
[6, 11]. Biogas production from wastes
is commonly achieved through anaerobic digestion. Biogas
67 P. A. Nwofe and P. E. Agbo: Enhancement of Biogas Yield from Cow Dung and Rice Husk Using Guano as Nitrogen Source
can be utilised as fuels both in low (household, village,
community) and large scale (industry) or as fertilisers [12-15].
The use of suitable nitrogen supplement or other parameters to
enhance biogas yield has been a subject of research for years.
Some authors [16, 17] have used different
supplement/parameters in this regard.