BIOGAS PRODUCTION FROM Xanthium strumarium L. LEAVES CO DIGESTED WITH GOAT MANURE IN A

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.