A multiple staged digestion system capable of digesting drylot manures is currently under development. The system is currently being validated at the pilot scale with three 1.5 cubic meter batch reactors. The system shows promise with various animal manure wastes as well as other common waste products. The first stage of the process is a dry digestion leachbed process in which the hydrolysis of solid waste products is optimized. The liquid leachate produced by the first stage is then transferred to a storage tank where the leachate is accumulated before use in the last stage. The last stage is optimized for methanogenesis and consists of a high rate methane reactor.
What Have We Learned?
This configuration of system components lends itself to a variety of potential advantages for regional digestion of animal wastes. Wastes of various solids contents can be segregated into the appropriate reactors, with high solids wastes placed in the first stage, moderate solids in the second stage, and primarily soluble wastes can be sent straight to the last stage. This inherent substrate flexibility could enable the construction of regional digesters capable of treating a wide array of wastes. As the solid wastes are dry digested dewatering at the end of the process is less challenging and leads the production of a high nutrient content soil amendment.
Future Plans
Plans are currently in the works to begin scaling this pilot system to build a 100-500kw on farm digester system.
Author
Lucas Loetscher lloetscher@gmail.com Colorado State University
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