Paper details

Title:

Digestion of Grass Silage and Dairy Slurry at Batch and Continuous Scale

Author(s):

Wall, D.M., O'Kiely, P., Murphy, J.D.

Document(s):

Abstract:

The predominant crop feedstock for anaerobic digestion in Germany and Austria is maize. Ireland, with a temperate climate, is more suited to the production of grass and can achieve high yields (upto 16 t DM ha­1). Grassland accounts for over 90% of agricultural land in Ireland. Irish agriculture is dominated by beef and milk production. Thus there is significant potential to produce biomethane from the co­digestion of grass silage and slurry. Mono­digestion of grass silage has been reported to give difficulties due to a deficiency in essential trace elements during long term operation. A comprehensive analysis of the digestion of grass silage and its co­digestion with dairy slurry has been undertaken in laboratory studies at both batch and continuous scale. The results illustrate that larger proportions of grass in the substrate mix correspond to higher specific methane yields. It was also shown that effluent liquor return improved the performance of the continuous digestion of grass silage in mono­and co­digestion, facilitating operation at higher organic loading rates. It is suggested that hydraulic retention time can be the limiting factor in the loading rate of grass based digesters.

Keywords:

agricultural residues, anaerobic digestion, methane, grass

Topic:

Biomass Conversion Technologies for Heating, Cooling and Electricity

Subtopic:

Anaerobic digestion for biogas production

Event:

22nd European Biomass Conference and Exhibition

Session:

2CO.5.3

Pages:

493 - 497

ISBN:

978-88-89407-52-3

Paper DOI:

10.5071/22ndEUBCE2014-2CO.5.3

Price:

FREE