Biogas Yield from Mesophilic to Thermophilic Digesters Using Cocoa Shell as Substrate

Abstract

Biogas is a clean and environmentally friendly renewable energy source that can be used as an alternative solution to reduce dependence on fossil energy in the future. This research was conducted to determine the effect of temperature variation on biogas yield from substrate of cocoa shell using cow manure as an inoculum. A batch system digester in a laboratory scale size was designed under different temperature operation of mesophilic to thermophilic temperature conditions. Initial characterization of cocoa shell was carried out to calculate the total solid and the amount of substrate feeding to a digester. Heating temperature variations used in the investigations were 40^oC, 45^oC and 50^oC for digester I, II and III respectively and digester IV, Vat environment temperature for comparison. In digesters I, II and III the substrate is stirred with an interval of 6 hours for 1 minute to avoid the formation of deposits and crust. The results of the study showed that the digester II was the most ideal temperature forcellulose degradation processproducing biogas accumulation pressures of 2.54 bar and specific volumes of 368.56 L / kg TS with the highest methane content of 56.8%.