Comparison of two laboratory methods for the determination of biomethane potential of organic feedstocks

• Two standardized methods were used to determine the biomethane potential of ten feedstocks that could be used in an anerobic digestion system.
• When BMP analysis for each feedstock was compared for each method, the majority of the feedstocks showed different results between methods.
• This study shows the varying results for the same feedstocks and highlights the importance of selecting an experienced testing laboratory.
• This is the first study to compare these BMP methods and shows how cautious one must be in comparing results between methods or testing facilities.

The increased interest in anaerobic digestion systems has led to the increased need for laboratories to conduct biomethane potential (BMP) to determine the possible usefulness of various feedstocks. There is currently no standard method, but two well established methods have emerged as standardized methods for BMP testing. These two methods are the Automated Methane Potential Testing System, or AMPTS and the German DIN standard method using eudiometers. While these are widely-used, there have been no comparison of how these systems relate to each other in terms of BMP results for identical feedstocks. This study compared the BMP results for ten feedstocks using both the AMPTS and DIN methods to see if the results can be directly related. Results suggest that the methods provide different BMP results for 8 of the ten tested feedstock (p < 0.05). Each method has advantages in terms of using it for BMPs, but overall results suggest that users of these methods should be aware of method differences when comparing results between methods or labs. For those interested in determining BMPs for larger-scale projects they should choose a testing facility that has experience with both methods and understands the differences in results between methods. While both methods can provide valuable information, it is important to be cautious in interpreting the results of these methods when compared to each other and likely the many in-house methods that various labs have developed.