Graphene Facilitates Biomethane Production from Protein-Derived Glycine in Anaerobic Digestion

Richen Lin; Chen Deng; Jun Cheng; Ao Xia; Piet N L Lens; Stephen A Jackson; Alan D W Dobson; Jerry D Murphy

doi:10.1016/j.isci.2018.11.030

Graphene Facilitates Biomethane Production from Protein-Derived Glycine in Anaerobic Digestion

iScience. 2018 Dec 21:10:158-170. doi: 10.1016/j.isci.2018.11.030. Epub 2018 Nov 22.

Authors

Richen Lin¹, Chen Deng², Jun Cheng³, Ao Xia⁴, Piet N L Lens⁵, Stephen A Jackson⁶, Alan D W Dobson⁶, Jerry D Murphy²

Affiliations

¹ MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland; School of Engineering, University College Cork, Cork, Ireland. Electronic address: richen.lin@ucc.ie.
² MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland; School of Engineering, University College Cork, Cork, Ireland.
³ State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou 310027, China.
⁴ Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, Ministry of Education, Chongqing 400044, China.
⁵ National University of Ireland Galway, University Road, Galway, Ireland.
⁶ MaREI Centre, Environmental Research Institute, University College Cork, Cork, Ireland; School of Microbiology, University College Cork, Cork, Ireland.

Abstract

Interspecies electron transfer is a fundamental factor determining the efficiency of anaerobic digestion (AD), which involves syntrophy between fermentative bacteria and methanogens. Direct interspecies electron transfer (DIET) induced by conductive materials can optimize this process offering a significant improvement over indirect electron transfer. Herein, conductive graphene was applied in the AD of protein-derived glycine to establish DIET. The electron-producing reaction via DIET is thermodynamically more favorable and exhibits a more negative Gibbs free energy value (-60.0 kJ/mol) than indirect hydrogen transfer (-33.4 kJ/mol). The Gompertz model indicated that the kinetic parameters exhibited linear correlations with graphene addition from 0.25 to 1.0 g/L, leading to the highest increase in peak biomethane production rate of 28%. Sedimentibacter (7.8% in abundance) and archaea Methanobacterium (71.1%) and Methanosarcina (11.3%) might be responsible for DIET. This research can open up DIET to a range of protein-rich substrates, such as algae.

Keywords: Chemical Engineering; Environmental Chemical Engineering; Microbial Biotechnology; Nanomaterials.