Enhanced Anaerobic Biogas Production From Wheat Straw by Herbal-Extraction Process Residues Supplementation.

Yonglan Xi,Yang Liu,Qingbo Xiao,Xiangping Kong,Dong Guo,Xiaomei Ye,Jing Du

doi:10.3389/fbioe.2021.623594

Abstract

Trace metals are essential constituents of cofactors and enzymes and that their addition to anaerobic digesters increases methane production. Many trace elements are contained in herbal-extraction process residues (HPR). The present study concerns the effect of six kinds of HPR [Danshen root (Dr), Astragalus membranaceus (Am), Isatis root (Ir), Angelica sinensis (As), and Pseudo-ginseng (Pg)] that were used as additives, respectively, in the anaerobic digestion of wheat straw on biogas and methane production. The ratios of HPR residues/wheat straw [based on total solids (TS), of wheat straw] were 3, 5, and 10%, respectively. The digesters were at 37 ± 1°C of water bath during 30 days of anaerobic digestion. The results showed that HPR had significant effects on the anaerobic co-digestion. The highest biogas productivity was achieved when treated with 10% Pseudo-ginseng residues (PGR), which yielded 337 ml/g TS of biogas and 178 ml/g TS of methane. Cumulative production of biogas and methane increased by 28 and 37% compared to the production achieved in the control. These results suggest that PGR is an effective HPR to enhance the production of methane.

Highlights

Methane production through anaerobic digestion of biomass has been considered as an attractive and potential method to obtain renewable biofuel due to its great environmental, societal, and economic benefits (Zhang et al, 2014; Rasapoor et al, 2020)
Cumulative Production of Biogas and Methane Is Affected by the Addition of Different Ratios of herbal-extraction process residues (HPR)
When 10% Pg was added in the digester, the highest biogas production was achieved, which increased 28% in comparison to the control

Summary

Introduction

Methane production through anaerobic digestion of biomass has been considered as an attractive and potential method to obtain renewable biofuel due to its great environmental, societal, and economic benefits (Zhang et al, 2014; Rasapoor et al, 2020). Anaerobic digestion (AD) is a naturally occurring phenomenon in which organic matter is decomposed by an assortment of microbes in an oxygen-free environment to produce biogas, composed primarily of methane (CH4) and carbon dioxide (CO2) (Frigon and Guiot, 2010; Esposito et al, 2012; Kumar and Samadder, 2020). China is a major agricultural country rich in the resources of biomass. Wheat straw as agricultural residues is considered an abundant renewable resource. The total annual production of wheat straw in China was 109 million metric tons in 2007 (Yang et al, 2010). The anaerobic digestion used in dealing with wheat straw is an attractive practice in which both pollution control and energy recovery can be achieved (Solé-Bund et al, 2017)

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Results