Biogas Production by Co-Digestion of Goat Manure with Three Crop Residues
Citation: Zhang T, Liu L, Song Z, Ren G, Feng Y, et al. (
Biogas Production by Co-Digestion of Goat Manure with Three Crop Residues
Tong Zhang 0
Linlin Liu 0
Zilin Song 0
Guangxin Ren 0
Yongzhong Feng 0
Xinhui Han 0
Gaihe Yang 0
Chenyu Du, University of Nottingham, United Kingdom
0 1 College of Forestry and the Research Center of Recycle Agricultural Engineering and Technology of Shaanxi Province, Northwest A&F University , Yangling, Shaanxi , People's Republic of China, 2 College of Agronomy and the Research Center of Recycle Agricultural Engineering and Technology of Shaanxi Province, Northwest A&F University , Yangling, Shaanxi , People's Republic of China
Goat manure (GM) is an excellent raw material for anaerobic digestion because of its high total nitrogen content and fermentation stability. Several comparative assays were conducted on the anaerobic co-digestion of GM with three crop residues (CRs), namely, wheat straw (WS), corn stalks (CS) and rice straw (RS), under different mixing ratios. All digesters were implemented simultaneously under mesophilic temperature at 3561 uC with a total solid concentration of 8%. Result showed that the combination of GM with CS or RS significantly improved biogas production at all carbon-to-nitrogen (C/N) ratios. GM/CS (30:70), GM/CS (70:30), GM/RS (30:70) and GM/RS (50:50) produced the highest biogas yields from different cosubstrates (14840, 16023, 15608 and 15698 mL, respectively) after 55 d of fermentation. Biogas yields of GM/WS 30:70 (C/N 35.61), GM/CS 70:30 (C/N 21.19) and GM/RS 50:50 (C/N 26.23) were 1.62, 2.11 and 1.83 times higher than that of CRs, respectively. These values were determined to be the optimal C/N ratios for co-digestion. However, compared with treatments of GM/CS and GM/RS treatments, biogas generated from GM/WS was only slightly higher than the single digestion of GM or WS. This result was caused by the high total carbon content (35.83%) and lignin content (24.34%) in WS, which inhibited biodegradation.
-
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" (2011BAD15B03) from Ministry of Science and Technology Department of the Peoples Republic of China, and the
Fundamental Research Funds for the Central Universities (QM2012002) from Ministry of Education of the Peoples Republic of China. The funders had no role in
study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
China is one of the largest agricultural countries in the world.
The production of net available crop residues (CRs) in China is
estimated to be over 800 million t/yr [1], which ranks first in the
world. The use of agricultural waste as a major component of
renewable energy is suitable for improving energy security and
decreasing environmental disruption caused by carbon emissions
[2,3]. Wheat straw (WS), rice straw (RS) and corn stalks (CS) are
the top three agricultural wastes in China and account for 80.5%
of the total output (15.7%, 24.2% and 40.6%, respectively) [1].
Thus, studying the energy generation potential of these three
wastes is important.
Anaerobic digestion (AD) is a biological process that produces
biogas from bio-degradable wastes by bacteria under poor or no
oxygen conditions. In the past two decades, AD has been applied
as an effective technology for solving the energy shortage and
environmental pollution problems of biotechnology industries and
residential activities caused by heating and electricity generation
[4,5,6].
CRs and animal manure have recently been used together to
produce biogas by AD. Compared with the single digestion of
feedstock, the co-digestion of CRs and animal manures increases
the rate of biogas production because of the greater balance
between carbon and nitrogen [7] and improves AD efficiency [8].
Annual goat manure (GM) yield in China is approximately
3.216108 t followed by dairy manure, swine manure and chicken
manure [9]. The total nitrogen (TN) contents of fresh GM (1.01%)
and chicken manure (1.03%) are significantly higher than those of
dairy manure (0.35%) and swine manure (0.24%) [10]. High TN
content is beneficial to co-digestion with CRs because it decreases
the carbon-to-nitrogen (C/N) ratios of single CRs substrates. GM
is also insensitive to acidification during anaerobic fermentation
[11,12]. Hence, GM is an excellent raw material for AD. Although
various raw materials, such as agricultural waste, animal manures,
sewage sludge and food waste have been reported as potentially
feasible for co-digestion [7,13,14,15,16,17,18,19,20], the suitable
mixing ratios of multi-component substrates between GM and
various CRs are largely unknown.
We investigated the biogas-producing efficiency of anaerobic
co-digestion influenced by different GM and CR mixing r (...truncated)