Is your anaerobic digestion system wet or dry? How categorizing anaerobic digester systems helps you understand features, constraints, and end products
An earlier blog post in this series discussed the many different parameters associated with anaerobic digesters (AD), and today I want to discuss how understanding the parameters that categorize the AD system provides an understanding of operational features, development constraints, as well as the end-products produced by the system.
Really the starting point or main differentiator is whether the AD is a wet or dry system. Another way to say it would be whether the system is considered pumpable (wet) or stackable (dry). You can go for wet/pumpable systems if your feedstock is in a form that can be pumped through a pipe into a tank for mixing. Manure, wastewater sludge or processed food waste that already has a high water content are good examples. With a feedstock that is high in solids, material is added to a chamber and percolate is used to start the process. A good example of a feedstock that might use a stackable/dry process is residential or commercial source separated organics.
Now, within these categories there are different ranges of wet or dry, tied to total solids (TS) content. Within the wet category there is a low solids (LS) and a high solids (HS) subcategory and within the dry there is only a HS subcategory, illustrated by the graphic shown.
Either of these two main, top tier categories can be broken down further as single or multi-stage or mesophylic or thermophylic to more elaborately “categorize” an AD system. You will hear many of these terms from the technology providers when describing their system offerings. Get familiar with the terms, but remember the first question to ask is, “Is this AD system a wet or dry system?
If you want to learn more about these categories and what they mean in practice, check out a recent presentation I gave on categorizing AD systems, called Anaerobic Digester System Selection for Organics.
Categories: Organics, Solid Waste
Posted By Prentiss Shaw, PE at 12:49 PM | No Comments on Is your anaerobic digestion system wet or dry? How categorizing anaerobic digester systems helps you understand features, constraints, and end products
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