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Differing Effects of Glycerin on Anaerobic Co-digestion of Mixed Substrates in Bench-Scale Assays and Sub Pilot-Scale Reactors
Agricultural and Biosystems Engineering Conference Proceedings and Presentations
  • Steven Thomas Sell, Iowa State University
  • D. Raj Raman, Iowa State University
  • Robert Burns, University of Tennessee–Knoxville
  • Robert P. Anex, University of Wisconsin–Madison
Document Type
Conference Proceeding
2011 ASABE Annual International Meeting
Publication Date
(38.2526647, -85.7584557)
Bench-scale methods such as Biochemical Methane Potential (BMP) assays and Anaerobic Toxicity Assays (ATAs) are useful tools in evaluating potential feedstocks for anaerobic digestion. The BMP method provides a preliminary indication of substrate biodegradability and methane production, while the ATAs provide an indication of substrate toxicity to anaerobic microbial consortia. Previous research using small (<20 >L) reactors indicated that co-digestion of manures with small amounts of glycerin (ca. 1 – 2 %) can double methane production, but toxicity can result if glycerin exceeds 2% (volumetric basis). This paper investigated the relationship between bench-scale methods (BMPs and ATAs) and sub pilot-scale digester results, using glycerin as a test substrate mixed with a baseline feedstock (beef manure, corn processing wastewater, lagoon liquid, and short-fiber cardboard). The batch-fed, stirred ATAs indicated that glycerin was toxic to methane production at all inclusion levels. The batch-fed, stirred BMPs indicated no significant difference between methane production in the 0.0%to 4.0% addition levels; however at 8.0% addition, methane production tripled. The continuously fed, non-stirred, plug-flow sub pilot-scale reactors indicated toxicity effects in the 2.0% and 4.0% glycerin mixtures and no difference from the control in the 1.0% glycerin mixture. These results demonstrate the variations in scale performance of glycerin as a co-substrate and identify some serious challenges in extrapolating bench-scale assays to large-scale performance of mixed-waste anaerobic digestion systems.

This is an ASABE Meeting Presentation, Paper No. 1111519.

Copyright Owner
American Society of Agricultural and Biological Engineers
Citation Information
Steven Thomas Sell, D. Raj Raman, Robert Burns and Robert P. Anex. "Differing Effects of Glycerin on Anaerobic Co-digestion of Mixed Substrates in Bench-Scale Assays and Sub Pilot-Scale Reactors" Louisville, KY(2011)
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