Lecture on: "Bioenergy from Waste: Methane Generation During Thermophilic Co-digestion"
“Bioenergy from Waste:
Methane Generation During Thermophilic Co-digestion”
by
Heidi Gough, PhD, PE
University of Washington, Department of Civil and Environmental Engineering
11:15 Am
Monday – 7th May 2012
Salaheldin Auditorium
ABSTRACT
Recent attention to carbon-neutral biofuels has revived interest in co-digestion for methane generation. During co-digestion, two waste products are blended to enhance methane production. At wastewater treatment facilities, energy-rich organic wastes may be co-digested with sludge using established anaerobic digester infrastructure. However, changes to organic loadings are known to induce digester processes instability – particularly for thermophilic digesters. To examine this problem, thermophilic (55°C) co-digestion was studied for two food-industry wastes in semi-continuous laboratory digesters, and the wastes’ biochemical methane potential (BMP) were tested. Wastes with high chemical oxygen demand (COD) were selected as feed stocks allowing input of potential energy to reactors without substantially altering volumetric loadings. Methane generation increased while reactor pH and volatile solids remained stable. Lag periods observed prior to methane stimulation suggested that acclimation of the microbial community may be critical to performance during co-digestion. COD mass balances in the experimental and control reactors indicated that all of the COD from the co-digested wastes was converted to methane
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