Anaerobic Digestion From the Laboratory to the Field: An Experimental Study Into the Scalability of Anaerobic Digestion

Anaerobic digestion (AD) is a unique organic waste treatment method that improves sanitation and environmental quality through pollution control, while providing organic fertilizer in the form of a liquid digestate and renewable energy in the form of clean-burning biogas. In designing AD systems efficiency is key. It can be costly in terms of time, money, and resources to dial-in systems once the full-scale has been constructed and is operational. For these reasons, bench-scale laboratory experimentation is an essential component of AD research and development. In order for bench-scale research to be applicable, a strong correlation between results obtained in the lab and actual performance of large-scale anaerobic digesters must exist. In this study, 100 mL, 1 L, and 10 L digesters treating equine waste were tested to determine the accuracy of scaling between digester sizes. Digesters were compared by the cumulative and daily biogas production, methane content, volatile solids-destruction, and pH of the digestate. Based on these results, a strong correlation was found between the yield of biogas and the digester sizes, showing that the scalability of AD is tenable, but that there is a scaling effect that must be taken into account.