It is easy to get carried away with Figure 2. It cannot be over emphasized that BMP analysis indicates the potential of substrates to produce methane under perfect laboratory conditions. It does not say how the substrate will behave in an actual digester. A co-digestion product may be toxic in higher doses than the small amount used in the BMP test.
If VS, COD, and BMP analyses reveal that a substrate is a good co-digestion product, then it is wise to determine maximum feeding rate of the material using an Anaerobic Toxicity Assay. Also, it is a good idea to pilot test – simulate the digest-er using a smaller reactor – before making any major changes to a digestion system.