Efficient anaerobic mono-digestion of N-rich slaughterhouse waste: influence of ammonia, temperature and trace elements

Bioresour Technol. 2014 Dec:174:222-32. doi: 10.1016/j.biortech.2014.10.023. Epub 2014 Oct 13.

Abstract

Three mono-digestion experiments treating slaughterhouse waste with high TKN concentration (∼11g/kg) were applied in lab-scale at mesophilic and psychrophilic conditions to study the impact of high ammonia concentrations and additives. Precipitation of sulphur by addition of ferrous chloride did not influence process behaviour, whereas supplementation of trace elements significantly improved process stability by reducing volatile fatty acid concentration towards zero. The limit of NH4-N concentration causing a rise of VFAs to 19,000mg/l and reduction of methane by 25% was found between 7.7 and 9.1g/kg which correspond to NH3 concentrations of 830-1060mg/l. Psychrophilic operation (25°C) lowered inhibitory NH3 concentration to 140mg/l, but process performance was stable only at low OLR of 0.4kgVS/m(3)d. Robust performance at highest possible NH4-N concentration (7.7g/kg), low VFA accumulation and satisfying methane yield of about 280Nm(3)/t COD was observed at OLR of 2.5kgVS/m(3)d at 37°C.

Keywords: Ammonia inhibition; Anaerobic mono-digestion; Ferrous chloride; Slaughterhouse waste; Trace elements.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abattoirs*
  • Ammonia / pharmacology*
  • Anaerobiosis / drug effects
  • Animals
  • Cattle
  • Ferrous Compounds / pharmacology
  • Hydrogen-Ion Concentration
  • Methane / analysis
  • Nitrogen / analysis*
  • Organic Chemicals / analysis
  • Refuse Disposal / methods*
  • Solid Waste / analysis*
  • Sus scrofa
  • Temperature*
  • Time Factors
  • Trace Elements / pharmacology*

Substances

  • Ferrous Compounds
  • Organic Chemicals
  • Solid Waste
  • Trace Elements
  • Ammonia
  • Nitrogen
  • Methane
  • ferrous chloride