Thermophilic Anaerobic Digestion of Pig Dung with Snail Shell Additive Supplementation for Enhanced Biogas Production

Abstract

The study investigated the thermophilic anaerobic digestion of pig dung with snail shell as additive for enhanced biogas production. Pig dung and additive was weighed and mixed with distilled water in a 500 ml round-bottom flask. The flask containing the slurry was connected to a Soxhlet extractor workstation, and was placed in a heating mantle. When heat was applied, the gas was conveyed through the thimble to the shell and tube heat exchanger, where the gas was condensed. The results show that the optimal conditions for biogas production were additive dosage at 3.5 g, pig dung/ water ratio at 0.16 g/ml, time at 60 mins and temperature at 70⁰C, under these conditions the biogas yield was 24.45 %. CCD of RSM was applied to enhance process optimization and predict the optimal outcome. The model demonstrated significant results, with a p-value of less than 0.0001. The R² of 0.9835, ANOVA results indicate that the model effectively describes the anaerobic digestion of pig dung for biogas production. The produced biogas contains 66.9% methane and 27.2% CO2 by volume with other constituents present as shown by gas chromatography and FTIR, therefore, the feedstocks used in this study have the potential to support the efficient and sustainable operation and production of biogas plants on a large scale.