Effects of temperature and carbon-nitrogen (C/N) ratio on the performance of anaerobic co-digestion of dairy manure, chicken manure and rice straw: focusing on ammonia inhibition

PLoS One. 2014 May 9;9(5):e97265. doi: 10.1371/journal.pone.0097265. eCollection 2014.

Abstract

Anaerobic digestion is a promising alternative to disposal organic waste and co-digestion of mixed organic wastes has recently attracted more interest. This study investigated the effects of temperature and carbon-nitrogen (C/N) ratio on the performance of anaerobic co-digestion of dairy manure (DM), chicken manure (CM) and rice straw (RS). We found that increased temperature improved the methane potential, but the rate was reduced from mesophilic (30∼40°C) to thermophilic conditions (50∼60°C), due to the accumulation of ammonium nitrogen and free ammonia and the occurrence of ammonia inhibition. Significant ammonia inhibition was observed with a C/N ratio of 15 at 35°C and at a C/N ratio of 20 at 55°C. The increase of C/N ratios reduced the negative effects of ammonia and maximum methane potentials were achieved with C/N ratios of 25 and 30 at 35°C and 55°C, respectively. When temperature increased, an increase was required in the feed C/N ratio, in order to reduce the risk of ammonia inhibition. Our results revealed an interactive effect between temperature and C/N on digestion performance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ammonia / metabolism*
  • Animals
  • Bacteria, Anaerobic / metabolism*
  • Biofuels*
  • Carbon / metabolism
  • Cattle
  • Chickens
  • Manure / microbiology*
  • Methane / biosynthesis*
  • Nitrogen / metabolism
  • Oryza
  • Plant Stems / microbiology
  • Temperature
  • Waste Disposal, Fluid / methods*

Substances

  • Biofuels
  • Manure
  • Carbon
  • Ammonia
  • Nitrogen
  • Methane

Grants and funding

This work was supported by science and technology support projects ‘the biological technology integration and demonstration of high yield biogas digestion from the mix ingredients’ (2011 BAD15B03) from Ministry of Science and Technology Department of the People’s Republic of China and Research Fund for the Doctoral Program of Higher Education of Northwest A & F University, China(2013BSJJ057). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.