Toward the complete utilization of rice straw: Methane fermentation and lignin recovery by a combinational process involving mechanical milling, supporting material and nanofiltration.
Rice straw was mechanically milled using a process consuming 1.9MJ/kg-biomass, and 10g/L of unmilled or milled rice straw was used as the carbon source for methane fermentation in a digester containing carbon fiber textile as the supporting material. Milling increased methane production from 226 to 419mL/L/day at an organic loading rate of 2180mg-dichromate chemical oxygen demand/L/day, corresponding to 260mLCH4/gVS. Storage of the fermentation effluent at room temperature decreased the weight of the milled rice straw residue from 3.81 to 1.00g/L. The supernatant of the effluent was subjected to nanofiltration. The black concentrates deposited on the nanofiltration membranes contained 53.0-57.9% lignin. Solution nuclear magnetic resonance showed that lignin aromatic components such as p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) were retained primarily, and major lignin interunit structures such as the β-O-4-H/G unit were absent. This combinational process will aid the complete utilization of rice straw.
Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
Kengo
K
Sasaki
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Mami
M
Okamoto
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan.
Tomokazu
T
Shirai
Institute for Frontier Science Initiative, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan.
Yota
Y
Tsuge
Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
Ayami
A
Fujino
Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
Daisuke
D
Sasaki
Environmental Chemistry Sector, Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-shi, Chiba-ken 270-1194, Japan.
Masahiko
M
Morita
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan; Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
Fumio
F
Matsuda
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan; Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehirocho, Tsurumi-ku, Yokohama 230-0045, Japan; Graduate School of Bioagricultural Sciences and School of Agricultural Sciences, Nagoya University, 1 Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Jun
J
Kikuchi
Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo 657-8501, Japan; RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan. Electronic address: akondo@kobe-u.ac.jp.
Akihiko
A
Kondo
D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D005285:Fermentation; D008031:Lignin / Q000302:isolation & purification / Q000378:metabolism; D008697:Methane / Q000737:chemistry*; D012275:Oryza / Q000737:chemistry* / Q000378:metabolism
D008031:Lignin; D008697:Methane
Mechanical milling; Methane fermentation; Nanofiltration; Nuclear magnetic resonance; Rice straw