Toward the complete utilization of rice straw: Methane fermentation and lignin recovery by a combinational process involving mechanical milling, supporting material and nanofiltration. (September 2016)

• Record Type: Journal Article
• Authors: Sasaki, Kengo; Okamoto, Mami; Shirai, Tomokazu; Tsuge, Yota; Fujino, Ayami; Sasaki, Daisuke; Morita, Masahiko; Matsuda, Fumio; Kikuchi, Jun; Kondo, Akihiko
• Is Part Of: Bioresource technology. Volume 216(2016)
• Page Start: 830
• Page End: 837
• Publication Date: 2016-09
• Subjects: Rice straw -- Mechanical milling -- Methane fermentation -- Nanofiltration -- Nuclear magnetic resonance; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2016.06.029
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: The complete utilization of rice straw was aimed. Methane fermentation was performed in a bioreactor containing supporting material. Mechanical milling (1.9 MJ/kg-rice straw) increased methane production (3.5 MJ). Nanofiltration recovered lignin that was released from the residue. 2D NMR showed that lignin aromatic components were recovered. Abstract: Rice straw was mechanically milled using a process consuming 1.9 MJ/kg-biomass, and 10 g/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 419 mL/L/day at an organic loading rate of 2180 mg-dichromate chemical oxygen demand/L/day, corresponding to 260 mLCH4 /gVS . Storage of the fermentation effluent at room temperature decreased the weight of the milled rice straw residue from 3.81 to 1.00 g/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.