[Digestion] Analytical Data on Feedstocks

[M. Charles Gould]

I work with farmers in West Michigan on manure management issues, and 
for the past several years have focused a lot of my time on anaerobic 
digestion as a component of a sustainable manure management plan. The 
increased numbers of biodiesel and ethanol plants in Michigan have 
presented the opportunity for dairy and swine farmers with digesters 
to use glycerin (a biodesiel by-product) and syrup stillage (an 
ethanol by-product) with manure to increase gas production. The 
mixing of these feedstocks has caught the eye of the Michigan 
Department of Environmental Quality (MDEQ). Because there are no 
regulations per se that deal with anaerobic digesters and products 
coming from anaerobic digesters, the MDEQ is feeling threatened and 
has given us a huge list of VOCs, SVOCs and metals to test for in 
order to get a solid waste exemption. The agriculture community has 
been down this road before in terms of exorbitant analytical testing 
required by the MDEQ, most recently with composting manure and animal 
mortalities. We want to avoid as much hassle as possible. Both myself 
and a colleague from the Michigan Department of Agriculture have 
mined the web for information and have talked with people we thought 
may have analytical data to show what is in the feedstocks and what 
is in the solid and liquid digestate after digestion. We are coming 
up empty for the most part, so I am asking you, an international 
audience, for some help. Can you direct me to published analytical 
data that shows the VOC, SVOC and metals content of feedstocks (such 
as glycerin, syrup stillage, food processing residuals, etc.) prior 
to going in a digester and the VOC, SVOC and metals content of both 
the liquid and solid digestate after digestion where various 
feedstock were added to manure?

Thank you for considering my request, and I look forward to your response!

Charles Gould
Grand Haven, MI
USA