Evaluation of Copper-Contaminated Marginal Land for the Cultivation of Vetiver Grass (Chrysopogon zizanioides) as a Lignocellulosic Feedstock and its Impact on Downstream Bioethanol Production

Abstract

Metal-contaminated soil could be sustainably used for biofuel feedstock production if the harvested biomass is amenable to bioethanol production. A 60-day greenhouse experiment was performed to evaluate (1) the potential of vetiver grass to phytostabilize soil contaminated with copper (Cu), and (2) the impact of Cu exposure on its lignocellulosic composition and downstream bioethanol production. Dilute acid pretreatment, enzymatic hydrolysis, and fermentation parameters were optimized sequentially for vetiver grass using response surface methodology (RSM). Results indicate that the lignocellulosic composition of vetiver grown on Cu-rich soil was favorably altered with a significant decrease in lignin and increase in hemicellulose and cellulose content. Hydrolysates produced from Cu exposed biomass achieved a significantly greater ethanol yield and volumetric productivity compared to those of the control biomass. Upon pretreatment, the hemicellulosic hydrolysate showed an increase in total sugars per liter by 204.7% of the predicted yield. After fermentation, 110% of the predicted ethanol yield was obtained for the vetiver grown on Cu-contaminated soil. By contrast, for vetiver grown on uncontaminated soil a 62.3% of theoretical ethanol yield was achieved, indicating that vetiver has the potential to serve the dual purpose of phytoremediation and biofuel feedstock generation on contaminated sites.

Phytomanagement of Metal(loid)-Contaminated Soils: Options, Efficiency and Value

“…Trees growing at brownfield and landfill sites can exhibit higher lignin content than those cultivated in uncontaminated soils due to abiotic stresses, e.g., drought-stress, leading to lower glucose yield (Edgar et al, 2021). In contrast, vetiver plants exposed to Cu excess can display a decrease in lignin and an increase in hemicellulose and cellulose contents, leading to a higher production rate of bioethanol (Geiger et al, 2019).…”

Impact of heavy metal ions on the simultaneous saccharification and fermentation of formosan alder biomass to form lactic acid

“…The fermentation efficiency of the heavy metal containing biomass was higher than the control biomass. Geiger et al (2019) indicated that hydrolysates produced from Cu exposed biomass achieved a significantly greater ethanol yield and volumetric productivity compared to those of the control biomass. Wu et al (2020) also showed that the Cd-accumulated biomass showed greatly enhanced enzymatic saccharification and bioethanol production by significantly increasing cellulose accessibility and lignocellulose porosity.…”

“…Previous studies have shown that the biomass harvested after phytoremediation could be utilized for bioethanol production (Ko et al 2017;Geiger et al 2019;Wu et al 2020). Ko et al (2017) found that the enzymatic hydrolysis efficiency for Zn-polluted biomass was 90% of the unpolluted biomass, while it was 77% for Cd, and approximately the same for Cr.…”

Energy-Saving Strategies and their Energy Analysis and Exergy Analysis for In Situ Thermal Remediation System of Polluted-Soil

“…At present, there are many studies on soil contamination, mainly about remediation methods, such as thermal desorption, chemical oxidation, phytoremediation etc. [19][20][21][22][23][24][25], assessment of contaminated soil [26], the process of soil contamination [27], areas for contaminated soil remediation, etc. [28].…”