Comparative Study on the Efficacy of Biogas Production from Mixture of Animal Waste and Pistia stratioles (Water Lettuce)

Abstract

Biogas was produced from the mixture of Sheep dung and Water lettuce (Pistia stratioles) in the ratio of 2:1 and 1:2 over a period of 77 days. Proximate analysis was done to determine the physicochemical parameters of each dried sample. Daily temperature of the laboratory, initial and final pH of the digesters containing slurry was recorded. This work was done to investigate the production of biogas from the mixture of sheep dung and water lettuce in order to improve the biogas production. Proximate analysis was done according to the methods described by Khanadainal and Malidi (1981) and AOAC (1990). Sheep dung and water lettuce were mixed in the ratio of 2:1 and 1:2 each in 900g empty milk tin and mixed with water to form slurry. Initial pH of each slurry was determined by inserting a digital pH meter. Final pH was determined after digestion. The gas was collected through a pipe connected to the digester which was inserted into a measuring cylinder filled with water and inverted in a container with water. Physical parameters determined for both sheep dung and water lettuce respectively include: Moisture (11% and 8.5%), Volatile Solid (6.2% and 8.7%) and Ash (19.5% and 44.5%). Initial and final pH of each digester was (7.30 and 7.20), and (6.67 and 6.38) for 2:1 and 1:2 ratio respectively. A total biogas of 17983.33cm³ and 8546.67cm³ were recorded by 2:1 and 1:2 ratio of sheep dung and water lettuce respectively. The production temperature ranged from 28°C to 36°C. Nature of substrates affects biogas production as revealed in this research.