[Ryan]

May a pose an alternative to that question… What is the most sustainable solution to digestate management?

From my perspective, that is land application as a fertilizer / soil amendment. This may not be feasible for all situations where further processing is needed to turn the material into something that could be bags and sold like compost. But in many situation, especially for on farm systems, that it the most desirable use. In someways an AD system is just borrowing the nutrients to control the production and capture of CH4, and those nutrients are still highly valuable for use as a fertilizer.