Locally abundant wastes have been investigated to establish
the possibility of utilising them as alternative source of energy,
thus the effect of different nitrogen sources (poultry droppings
and guano) on the biogas yield from cow dungs from N'dama
species and rice husk has been reported. The results show that
the use of guano as nitrogen supplement is more promising
than poultry droppings. A maximum biogas production rate of
85 mL/day and 60 mL/day were obtained for guano
supplement in RH and CD respectively while poultry
droppings in both feedstocks gave lower biogas yield. The
other parameters: initial PH, water dilution, nitrogen source
(guano and poultry droppings) and trace metals also affected
the digester performance. Our findings show that a feed to
water dilution ratio of 1:6 w/v yielded maximum cumulative
biogas of 450 mL/day for RH and 350 mL/day for CD. At
initial pH of 7.0 for both feedstocks, Ni2+ (100 ppm) for rice
husk, and Zn2+ (100 ppm) for cow dung gave the best biogas
yield while Fe2+ show no effect in RH and CD respectively.
All the parameters tested increased the biogas yield without
affecting the methane content. The findings reported herein
could serve as a useful guide for further research to optimise
the conditions needed to improve biogas yield from locally
available and abundant wastes