Low-temperature torrefaction assisted with solid-state KOH/urea pretreatment for accelerated methane production in wheat straw anaerobic digestion

Zhijiang Shao; Pitchaimari Gnanasekar; Nicole Tratnik; Nicolas R Tanguy; Xiaohui Guo; Mingqiang Zhu; Ling Qiu; Ning Yan; Heyu Chen

doi:10.1016/j.biortech.2023.128940

Low-temperature torrefaction assisted with solid-state KOH/urea pretreatment for accelerated methane production in wheat straw anaerobic digestion

Bioresour Technol. 2023 Jun:377:128940. doi: 10.1016/j.biortech.2023.128940. Epub 2023 Mar 21.

Authors

Zhijiang Shao¹, Pitchaimari Gnanasekar², Nicole Tratnik³, Nicolas R Tanguy⁴, Xiaohui Guo¹, Mingqiang Zhu¹, Ling Qiu¹, Ning Yan⁵, Heyu Chen⁶

Affiliations

¹ College of Mechanical and Electronic Engineering, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi 712100, China; Northwest Research Center of Rural Renewable Energy Exploitation and Utilization of M.O.A, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi 712100, China.
² Department of Chemical and Biomedical Engineering, National High Magnetic Field Laboratory, FAMU-FSU College of Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310, USA.
³ Graduate Department of Forestry, University of Toronto, 33 Willcocks Street, M5S 3B3, Canada.
⁴ Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, Coyoacán, CDMX 04510, México.
⁵ Graduate Department of Forestry, University of Toronto, 33 Willcocks Street, M5S 3B3, Canada; Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, M5S 3E5, Canada.
⁶ College of Mechanical and Electronic Engineering, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi 712100, China; Northwest Research Center of Rural Renewable Energy Exploitation and Utilization of M.O.A, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi 712100, China. Electronic address: [email protected].

PMID: 36958681
DOI: 10.1016/j.biortech.2023.128940

Abstract

Low-temperature torrefaction assisted with solid-state KOH/urea applied onto wheat straw was proposed to break down the lignocellulosic material to enhance biomethane production in anaerobic digestion (AD). The optimization of key parameters applying the Box-Behnken design and response surface methodology showed that an addition of 0.1 g/g_straw KOH/urea at 180 °C while torrefying for 30 min was the optimal condition for producing biomethane. Results indicate that co-applying KOH and urea in torrefaction synergistically enhanced the biodegradability of straw by effectively removing lignin and largely retaining cellulose, giving rise to a 41 % increase in the cumulative methane production compared to untreated straw (213 mL/g-volatile solids (VS_raw)) from batch AD. Additionally, the nitrogen- and potassium-rich digestates helped to improve soil fertility, thus achieving a zero-waste discharge. This study demonstrated the feasibility of using solid-state KOH/urea assisted low-temperature torrefaction as an effective pretreatment method to promote methane production during AD.

Keywords: Agricultural wastes; Alkaline pretreatment; Biogas; Response surface methodology.

MeSH terms

Anaerobiosis
Biofuels
Methane
Temperature
Triticum*
Urea*

Substances

Urea
Methane
Biofuels