Effectiveness of Biogas Production from Slaughter Waste using Two Mixing Ratios (Waste: Water Ratio of 1:1 and 1:2)

Biogas technology is widely used as a better alternative in the handling of waste in many societies in the world. This paper looks at the yield and the composition of biogas produced from slaughter waste using these two mixing ratios with a retention period of forty days. The study revealed that the 1:1 ratio gave 27.92 liters of Biogas per kilogram of waste, while the 1:2 gave 31.46 liters of Biogas per kilogram of waste. Analysis of the Biogas also revealed that for the 1:1 ratio, the composition of the Biogas was 67% methane, 30.7% carbon dioxide, 0.7% Hydrogen sulphide and 1.6% Oxygen. For the 1:2 ratio, the composition was 70.5% methane, 27.2% carbon dioxide, 0.6% Hydrogen sulphide and 1.7% Oxygen. The study therefore concludes that the 1:2 ratio was a better option for mixing waste and water when producing Biogas from slaughter waste. Keywords: Biogas, Retention period, Slaughter waste, Methane, Carbon dioxide, Hydrogen sulphide, Oxygen

Substrate-induced pH changes and process stability of anaerobic digestion of shea waste

Shea butter extraction involves the generation of waste of environmental concern. To help find a solution to the management of this waste, and to search for an alternative source of energy, this study was carried out to investigate the potential of shea waste in generating methane gas through anaerobic digestion. At high concentrations, volatile fatty acids produce a low pH, which may inhibit hydrolysis, thereby affecting the stability of the anaerobic digestion process. The influence of pH changes on process stability (or otherwise) was also investigated. The study involved two fermentation processes: mono-fermentation and co-fermentation involving a mix of shea waste and cattle dung. The mono-fermentation investigations comprised six treatments - three organic dry matter concentrations of 7%, 5% and 3%, combined with two hydraulic retention times of 30 and 60 days. The co-fermentation investigations comprised three treatments of shea waste and cattle manure mix in proportions (by volume) of 50:50, 75:25 and 90:10. The results showed that changes in pH were a good parameter for indicating process instability. The results also showed that monofermentation of shea waste was not a viable option in anaerobic digestion for biogas production, whilst only the substrate with 50% cattle manure in the co-fermentation trials showed process stability, producing biogas with adequate methane content

Substrate-Induced pH Changes and Process Stability of Anaerobic Digestion of Shea Waste

Shea butter extraction involves the generation of waste of environmental concern. To help find a solution to the management of this waste, and to search for an alternative source of energy, this study was carried out to investigate the potential of shea waste in generating methane gas through anaerobic digestion. At high concentrations, volatile fatty acids produce a low pH, which may inhibit hydrolysis, thereby affecting the stability of the anaerobic digestion process. The influence of pH changes on process stability (or otherwise) was also investigated. The study involved two fermentation processes: mono-fermentation and co-fermentation involving a mix of shea waste and cattle dung. The mono-fermentation investigations comprised six treatments - three organic dry matter concentrations of 7%, 5% and 3%, combined with two hydraulic retention times of 30 and 60 days. The co-fermentation investigations comprised three treatments of shea waste and cattle manure mix in proportions (by volume) of 50:50, 75:25 and 90:10. The results showed that changes in pH were a good parameter for indicating process instability. The results also showed that monofermentation of shea waste was not a viable option in anaerobic digestion for biogas production, whilst only the substrate with 50% cattle manure in the co-fermentation trials showed process stability, producing biogas with adequate methane content