Synergistic effect in anaerobic co-digestion of rice straw and dairy manure - a batch kinetic study

ABSTRACT

Methane yield of seven co-digestion mixture proportions (1:0, 5:1, 3:1, 1:1, 1:3, 1:5, and 0:1) of rice straw and dairy manure was investigated at a total solids (TS) loading of 8%. Methane yield was improved by 50–57% and 9–10% with co-digestion at mixture proportions of 1:1,1:3 and 1:5 compared to mono digestion of rice straw and dairy manure, respectively. The modified Gompertz model accounted well for the kinetic behavior of methane yield with an R² of 0.99 and Root Mean Square Error of 0.06–1.70. It was observed that the co-digestion caused a reduction in lag phase time and improvement in the maximum methane production rate. The positive synergistic effects are a result of nutrient balance with the co-digestion of dairy manure and rice straw.

KEYWORDS:

• Anaerobic co-digestion
• biogas
• methane
• rice straw
• dairy manure

Acknowledgments

The authors wish to thank Department of Biotechnology, Ministry of Science & Technology Government of India for funding this work and Department of Civil Engineering, National Institute of Technology, Warangal, India for providing support to carry out present work. The authors also wish to thank Dr. M. Raja Vishwanathan, Assistant Professor, Department of Humanities & Social Science, NIT Warangal for proof reading.

Additional information

Funding

This work was supported by the Department of Biotechnology, Ministry of Science and Technology [BT/PR6328/GBD/27/387/2012].