Methane emissions from digestate at an agricultural biogas plant.
Methane (CH4) emissions were measured over two years at an earthen storage containing digestate from a mesophilic biodigester in Ontario, Canada. The digester processed dairy manure and co-substrates from the food industry, and destroyed 62% of the influent volatile solids (VS). Annual average emissions were 19gCH4m(-3)d(-1) and 0.27gCH4kg(-1)VSd(-1). About 76% of annual emissions occurred from June to October. Annual cumulative emissions from digestate corresponded to 12% of the CH4 produced within the digester. A key contributor to CH4 emissions was the sludge layer in storage, which contained as much VS as the annual discharge from the digester. These findings suggest that digestate management provides an opportunity to further enhance the benefits of biogas (i.e. reducing CH4 emissions compared to undigested liquid manure, and producing renewable energy). Potential best practices for future study include complete storage emptying, solid-liquid separation, and storage covering.
Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada.
Hambaliou
H
Baldé
Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada. Electronic address: Andrew.VanderZaag@agr.gc.ca.
Andrew C
AC
VanderZaag
Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada.
Stephen D
SD
Burtt
School of Environmental Sciences, University of Guelph, Ontario, Canada.
Claudia
C
Wagner-Riddle
Ontario Ministry of Agriculture Food and Rural Affairs, Kemptville, ON, Canada.
Anna
A
Crolla
Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada.
Raymond L
RL
Desjardins
Environment Canada, Gatineau, Quebec, Canada.
Douglas J
DJ
MacDonald
D000383:Agriculture; D000393:Air Pollutants / Q000032:analysis*; D056804:Biofuels; D001709:Biotechnology / Q000379:methods*; D002245:Carbon Dioxide / Q000032:analysis; D003612:Dairying; D000072480:Farms; D019649:Food Industry; D008372:Manure; D008697:Methane / Q000032:analysis*; D009864:Ontario
D000393:Air Pollutants; D056804:Biofuels; D008372:Manure; D002245:Carbon Dioxide; D008697:Methane
Anaerobic digestion; Backward Lagrangian Stochastic; Biogas plant; Digestate; Methane