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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.

Wang X, Lu X, Li F, Yang G - PLoS ONE (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, People's Republic of China.

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.

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Changes of methane potential with different C/N ratios in the mixture of dairy manure (DM), chicken manure (CM), and rice straw (RS) in anaerobic co-digestion at 35°C and 55°C.The dotted lines were fitting curves for both temperatures. Values are presented as the mean ±standard error of three replicates (n = 3). Vertical bars represent LSD at the 5% level.
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pone-0097265-g004: Changes of methane potential with different C/N ratios in the mixture of dairy manure (DM), chicken manure (CM), and rice straw (RS) in anaerobic co-digestion at 35°C and 55°C.The dotted lines were fitting curves for both temperatures. Values are presented as the mean ±standard error of three replicates (n = 3). Vertical bars represent LSD at the 5% level.

Mentions: Methane potential increased first and then decreased with increases of C/N ratios. The highest methane potential was observed with a C/N ratio of 25 at 35°C with 272 mL g−1VS and with a C/N ratio of 30 at 50°C with 286 mL g−1VS, respectively (Fig. 4). The quadratic models for methane potential in terms of the C/N ratio as a variable were significant and the equations at 35°C (1) and 55°C (2) were expressed as follows:


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.

Wang X, Lu X, Li F, Yang G - PLoS ONE (2014)

Changes of methane potential with different C/N ratios in the mixture of dairy manure (DM), chicken manure (CM), and rice straw (RS) in anaerobic co-digestion at 35°C and 55°C.The dotted lines were fitting curves for both temperatures. Values are presented as the mean ±standard error of three replicates (n = 3). Vertical bars represent LSD at the 5% level.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016299&req=5

pone-0097265-g004: Changes of methane potential with different C/N ratios in the mixture of dairy manure (DM), chicken manure (CM), and rice straw (RS) in anaerobic co-digestion at 35°C and 55°C.The dotted lines were fitting curves for both temperatures. Values are presented as the mean ±standard error of three replicates (n = 3). Vertical bars represent LSD at the 5% level.
Mentions: Methane potential increased first and then decreased with increases of C/N ratios. The highest methane potential was observed with a C/N ratio of 25 at 35°C with 272 mL g−1VS and with a C/N ratio of 30 at 50°C with 286 mL g−1VS, respectively (Fig. 4). The quadratic models for methane potential in terms of the C/N ratio as a variable were significant and the equations at 35°C (1) and 55°C (2) were expressed as follows:

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: College of Agronomy, Northwest A&F University, Yangling, Shaanxi, People's Republic of China.

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.

Show MeSH
Related in: MedlinePlus