Abstract:
Biogas production is one of the technologies that can overcome the problems related to
energy Crisis. Therefore, this research was conducted to investigate the biogas production
potential of Xanthium strumarium leaves in combination with goat manure in anaerobic
condition. Completely randomized experimental design was used under mesophilic condition
(38ºC). Five batch fermentation treatments (T1=100% goat manure, T2=75% goat
manure:25% Xanthium strumarium, T3=50% goat manure:50% Xanthium strumarium,
T4=25% goat manure:75% Xanthium strumarium and T5=100% Xanthium strumarium) was
used with triplicate in total solid content adjusted to 8% in 0.5 plastic bottle digester for 30
days of fermentation period. In all treatments, Physico-chemical parameters such as total
solids (TS), volatile solids (VS), organic carbon, total nitrogen, carbon to nitrogen ratio and
pH were measured and were significantly varied before and after anaerobic digestion
(P<0.05). The pH of all digesters significantly varied after anaerobic digestion. After
anaerobic digestion, %TS, % OC, and %VS significantly decreased in all treatments.
However, highest reduction was recorded in T4=75% Xanthium strumarium: 25% goat
manure. Before anaerobic digestion, carbon to nitrogen ratio (C: N) of all treatments were
found in between the recommended range 20:1 to 30:1 which was a suitable condition for
methanogenic bacteria to reproduce and produce optimum biogas. Daily biogas production
was observed in all mix ratios of each treatment from the first day of the experiment and after
the 12th day of fermentation, biogas yield decreased gradually in all digesters and eventually
dropped to zero around the 30th day of fermentation. The daily biogas production was
subsequently measured by water displacement method and summed up to get the cumulative
biogas yield over the entire incubation period. The highest cumulative biogas production
(1317.5 mL) was recorded in a mix ratio of 75% Xanthium strumarium and 25% goat manure
substrates than other treatments, suggesting this mix ratio of the two substrates is an optimal
mix ratio to enhance biogas production potential in an anaerobic condition.
