Hostname: page-component-77f85d65b8-8v9h9 Total loading time: 0 Render date: 2026-03-27T11:36:40.896Z Has data issue: false hasContentIssue false

Thermophilic solid state anaerobic digestion of switchgrass for liquid digestate reuse and organic fertilizer production

Published online by Cambridge University Press:  11 April 2019

Jianjun Zang*
Affiliation:
State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing100193, China
Jason C. H. Shih
Affiliation:
Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC27695, USA
Jay J. Cheng
Affiliation:
Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC27695, USA
Zhimin Liu
Affiliation:
Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC27695, USA
Ying Liu
Affiliation:
Guangdong Engineering Research Centre for Marine Algal Biotechnology, Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen518060, China
Wenqing Lu
Affiliation:
State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing100193, China
*
Author for correspondence: Jianjun Zang, E-mail: zangjj@cau.edu.cn

Abstract

Two solid state anaerobic digesters (SSADs), 15 L each, were set up for co-digestion of switchgrass with primary digestate of a liquid anaerobic digester (LAD) and the recirculating leachate. Both the LAD and two SSADs were operated at 50°C. The results showed that the bioreactors were not started up stably until day 16 and day 47 for reactors A and B, respectively. The supplement of LAD digestate or injection of sodium hydroxide (NaOH) into the recirculating leachate readily reinitiated the biogas production to normal daily high rates of the two individual SSADs, one on day 16 and the other on day 47. In contrast to reactor A, there was a longer lag phase for bioreactor B, however, it showed 46.2% [77.9 vs 53.3 L kg−1 volatile solid (VS)] more cumulative biogas yields, and higher reduction rate of total solid, VS, cellulose and hemicellulose of 29.5, 31, 40.6 and 15%, respectively, which was likely due to optimized pH and NaOH pretreated switchgrass during start-up period. Methane contents of biogas increased gradually and stabilized at 50% for both reactors, indicating a normal operation of anaerobic digestion lasted for at least 100 days. The determined parameters of digested residues met China organic fertilizer standard (NY 525-2012) except for high moisture and low total nutrient contents. Therefore, the product of SSAD has the potential value of organic fertilizer. It is concluded that the LAD digestate can be reused as inoculums by co-digestion with agricultural residues for biogas and organic fertilizer production in SSAD.

Information

Type
Research Paper
Copyright
Copyright © Cambridge University Press 2019

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable