Anaerobic co-digestion of forage radish and dairy manure in complete mix digesters

Bioresour Technol. 2015 Feb:178:230-237. doi: 10.1016/j.biortech.2014.09.036. Epub 2014 Sep 16.

Abstract

Pilot-scale digesters (850 L) were used to quantify CH4 and H2S production when using forage radish cover crops as a co-digestion feedstock in dairy manure-based digesters. During two trials, triplicate mixed digesters were operated in batch mode with manure-only or radish+manure (27% and 13% radish by wet weight in Trial 1 and 2, respectively). Co-digestion increased CH4 production by 11% and 39% in Trial 1 and 2, respectively. As H2S production rapidly declined in the radish+manure digesters, CH4 production increased reaching high levels of CH4 (⩾67%) in the biogas. Over time, radish co-digestion lowered the H2S concentration in the biogas (0.20%) beyond that of manure-only digestion (0.34-0.40%), although cumulative H2S production in the radish+manure digesters was higher than manure-only. Extrapolated to a farm-scale (200 cows) continuous mixed digester, co-digesting with radish could generate 3150 m(3) CH4/month, providing a farmer additional revenue up to $3125/month in electricity sales.

Keywords: Anaerobic digestion; Biogas; Cover crops; Hydrogen sulfide; Methane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaerobiosis
  • Animals
  • Bioreactors
  • Cattle
  • Dairying*
  • Hydrogen Sulfide / analysis
  • Hydrogen-Ion Concentration
  • Manure / analysis*
  • Methane / biosynthesis
  • Nitrogen / analysis
  • Phosphorus / analysis
  • Raphanus / chemistry*
  • Refuse Disposal / instrumentation*
  • Refuse Disposal / methods*
  • Sulfur / analysis
  • Waste Disposal, Fluid

Substances

  • Manure
  • Phosphorus
  • Sulfur
  • Nitrogen
  • Methane
  • Hydrogen Sulfide