Cattle manure for biogas production. Does ensiling and wheat straw addition enhance preservation of biomass and methane potential?

ABSTRACT

The effects of ensiling and open-air storage on the conservation of cattle manure were investigated for 120 days at laboratory scale. The impact of co-ensiling with wheat straw was assessed as well. Up to 74% of methane potential was lost during aerobic storage. Negligible energetic losses and ammonia emissions occurred during the first month of anaerobic preservation. However, inadequate chemical properties of fresh cattle manure hindered silage stabilization for extended periods, leading to 46% methane losses after 4 months. Co-ensiling of cattle manure with wheat straw enhanced biomass acidification, inducing a conservation of more than 86% of the methane potential after 4 months. Wheat straw addition suppressed ammonia production and limited the risks of losses through liquid effluent. The current study proves that long-term conservation of cattle manure can be achieved if correct management practices are used, which will undoubtedly improve the performance of biogas plants with this raw material.

Highlights

• Ensiling enhanced biomass and methane conservation of cattle manure

• Ammonia emissions during storage are minimized through ensiling

• Co-ensiling with wheat straw stabilized biomass at elevated pH value

• Wheat straw addition minimized risk of losses through effluent production

• Silage with wheat straw conserved at least 86% of methane potential after 4 months

KEYWORDS:

• Cattle manure
• storage
• ensiling
• anaerobic digestion
• methane potential

Acknowledgements

Rúben Teixeira Franco held a doctoral fellowship from the Rhône-Alpes region. This work was undertaken within the SAM project (Stockage Avant Méthanisation – Storage Before AD) funded by ADEME (# 1506C0038). The authors thank the DEEP laboratory team, including David Lebouil, Hervé Perier-Camby, Nathalie Dumont and Richard Poncet, for the support given during the tests. We are grateful to Franck Barra for his permanent availability for discussion and raw material supply. Mathilde Hardier and SUEZ are also acknowledged for the inoculum provided for the BMP tests.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the SAM project (Stockage Avant Méthanisation – Storage Before AD) funded by ADEME [grant number # 1506C0038].