Investigating the use of charcoal to improve biogas production from pig litter

Abstract

With the increasing population in the country and all over the world, there is an increase in the demand of energy supplied. Fossil fuels being non-renewable and non-environmental friendly, other alternatives for fossil fuels are being sought for worldwide. One such of alternatives is the biogas energy. In Uganda where majority of the population lives in rural areas and survives on agriculture, biogas energy is utilized but unfortunately still inefficient. This study thus investigates the use of charcoal additive in improving the biogas production from pig manure. In this study anaerobic digestion was carried for a period of 25 days for setups carrying pig litter alone and pig litter with varying percentages of the charcoal additive. Percentages of 2% charcoal of the substrate, 5% charcoal of the substrate, and 10% charcoal of the substrate. The charcoal and pig litter samples were prepared, characterised, and fed in digesters of 5 litres capacity in size. Sodium hydroxide was used to remove carbon dioxide from the biogas produced. In the data collected, the setup with charcoal additives charcoal of the substrate produced the more biogas as compared to the setup without charcoal. This was chalked down to charcoal stimulating bacterial activity and increasing the surface area for adhesion inside the digester. Charcoal was also known to provide a favourable pH for anaerobic digestion. Between the set-up with 5% charcoal of the substrate and 10% charcoal of the substrate, it was expected for the latter to produce more biogas but it was found to not be the case. This was perceived to be due to more carbon dioxide formation compared to biogas production.