Physico-Chemical Alternatives in Lignocellulosic Materials in Relation to the Kind of Component for Fermenting Purposes

Abstract

The complete bioconversion of the carbohydrate fraction is of great importance for a lignocellulosic-based biorefinery. However, due to the structure of the lignocellulosic materials, and depending basically on the main parameters within the pretreatment steps, numerous byproducts are generated and they act as inhibitors in the fermentation operations. In this sense, the impact of inhibitory compounds derived from lignocellulosic materials is one of the major challenges for a sustainable biomass-to-biofuel and -bioproduct industry. In order to minimise the negative effects of these compounds, numerous methodologies have been tested including physical, chemical, and biological processes. The main physical and chemical treatments have been studied in this work in relation to the lignocellulosic material and the inhibitor in order to point out the best mechanisms for fermenting purposes. In addition, special attention has been made in the case of lignocellulosic hydrolysates obtained by chemical processes with SO2, due to the complex matrix of these materials and the increase in these methodologies in future biorefinery markets. Recommendations of different detoxification methods have been given.

Detoxification of a Lignocellulosic Waste from a Pulp Mill to Enhance Its Fermentation Prospects

“…The fact that SSL detoxification is completely necessary was already discussed by Coz et al [26]. Discussion of Figure 5b was possible assuming total and individual inhibitor losses obtained in this work for overliming, exchange resins and adsorption.…”

“…LS have adhesive and dispersant properties which make them feasible for fabrication of composite boards. As pointed out by Coz et al [26], it is more difficult to separate the sugar substrate from the rest of the inhibitors, mainly because the lignosulfonates act as glue in the mixture.…”

“…In recent years, many publications have studied a single detoxification technique coupled with a specific fermentation scenario [2,9,16,19,23,35]. Other papers have studied the combination of detoxification techniques experimentally [10,17,18,20,21,36,37] or from a theoretical viewpoint [26,31,38,39]. Nonetheless, the present research is the first paper working with spent sulfite liquor which compares different detoxification techniques showing which one of them would be adequate to produce seven different fermentation and value-added products (ethanol, bacterial cellulose, xylitol, polyhydroxyalkanoate (PHA), acetone-butanol-ethanol (ABE), succinic acid and polyhydroxybutyrate (PHB).…”

Effect of Enzymatic Beech Fagus Sylvatica Wood Hydrolysate on Chlorella Biomass, Fatty Acid and Pigment Production

“…In our previous study [13], neutralized beech wood diluted acid hydrolysate at a 12% loading partially inhibited Chlorella growth, when compared to a synthetic organic carbon-based medium. In the literature, lignocellulosic hydrolysates contain a range of compounds that inhibit the metabolism of yeast [26,27], and can also negatively affect microalgae growth [10]. In the present study, neutralized enzymatic beech wood hydrolysate at 10% loading (TGP-Enz10) also inhibited Chlorella growth.…”

Controllable synthesis of monoacrylate‐modified adsorption resins and enhancing adsorption toward fermentation inhibitors from rice straw hydrolysate

“…To eradicate the adverse effects of these compounds and maximize the levels of sugars in the fermentation media, different physical methods, vacuum evaporation, liquid–liquid extraction, membranes operation, as well as adsorption have been tested for purification of lignocellulosic hydrolysate . Vacuum evaporation is used to remove the amounts of inhibitors that are associated with volatile compounds, while nonvolatile fraction is still present .…”