A 100 g of each feedstock (CD and RH) was included in
conical asks and then mixed with varying quantities of
nitrogen sources (poultry droppings and guano). The poultry
droppings were sourced from poultry farms while the bat
droppings were obtained from aged-buildings roofed with
corrugated iron sheets in the rural areas of Ebonyi State. The
controls had the same quantity of feedstock without nitrogen source. A feed to poultry droppings/guano ratio of 2.5:1 (w/w)
was formed by mixing a 100 g of CD and RH respectively
with 40g of poultry droppings/guano in different digesters.
The fermentation process in each case was induced by adding
350 mL of water to the same volume of cow rumen as before.
The hydraulic retention time was 30 days while the incubation
temperature was maintained at 31±1oC.
Concentrations of Fe3SO4, ZnSO4 and NiCl2 in the range
40-250 ppm were added to each digester containing 55 g of
CD and RH respectively, to investigate the effect of the heavy
metal on the biogas production rate. In particular, 250 mL of
each solution was added to the digesters. The control in each
case had 250 mL of water included only. Fermentation was
induced by innoculating each digester with a 55 mL of freshly
strained cow rumen liquor.