Fermentative Conversion of Two-Step Pre-Treated Lignocellulosic Biomass to Hydrogen

Abstract

Fermentative hydrogen production via dark fermentation with the application of lignocellulosic biomass requires a multistep pre-treatment procedure, due to the complexed structure of the raw material. Hence, the comparison of the hydrogen productivity potential of different lignocellulosic materials (LCMs) in relation to the lignocellulosic biomass composition is often considered as an interesting field of research. In this study, several types of biomass, representing woods, cereals and grass were processed by means of mechanical pre-treatment and alkaline and enzymatic hydrolysis. Hydrolysates were used in fermentative hydrogen production via dark fermentation process with Enterobacter aerogenes (model organism). The differences in the hydrogen productivity regarding different materials hydrolysates were analyzed using chemometric methods with respect to a wide dataset collected throughout this study. Hydrogen formation, as expected, was positively correlated with glucose concentration and total reducing sugars amount (YTRS) in enzymatic hydrolysates of LCMs, and negatively correlated with concentrations of enzymatic inhibitors i.e., HMF, furfural and total phenolic compounds in alkaline-hydrolysates LCMs, respectively. Interestingly, high hydrogen productivity was positively correlated with lignin content in raw LCMs and smaller mass loss of LCM after pre-treatment step. Besides results of chemometric analysis, the presented data analysis seems to confirm that the structure and chemical composition of lignin and hemicellulose present in the lignocellulosic material is more important to design the process of its bioconversion than the proportion between the cellulose, hemicellulose and lignin content in this material. For analyzed LCMs we found remarkable higher potential of hydrogen production via bioconversion process of woods i.e., beech (24.01 mL H2/g biomass), energetic poplar (23.41 mL H2/g biomass) or energetic willow (25.44 mL H2/g biomass) than for cereals i.e., triticale (17.82 mL H2/g biomass) and corn (14.37 mL H2/g biomass) or for meadow grass (7.22 mL H2/g biomass).

Management of Dark Fermentation Broth via Bio Refining and Photo Fermentation

“…The coupling of dark fermentation with mentioned processes may increase the hydrogen efficiency and decrease the COD of the remaining medium [15,26,28]. Considering the hydrogen formed during biological processes may be contaminated with NH 3 , CO 2 , CH 4 , H 2 S, a gaseous stream purification must be concerned.…”

“…On the other hand, the process parameters require optimization. Therefore, based on original research [9,10,28,31,32], model broths were prepared. The initial dark fermentation broth was composed of a sterile minimal medium Buffered Peptone Water (Biomaxima, Gdańsk, Poland) and lignocellulosic biomass hydrolysates, as the sole carbon source for hydrogen-generating anaerobic microorganisms; i.e., Enterobacter aerogenes ATCC 13048 [10].…”

Multi-Step Exploitation of Raw Arundo donax L. for the Selective Synthesis of Second-Generation Sugars by Chemical and Biological Route

“…For this reason, Arundo donax L. is widely used as a substrate for the synthesis of important platform-chemicals, biofuels, and second-generation sugars [14,16,25,27,35,[46][47][48]. In particular, the interest towards the synthesis of xylose and glucose is continuously growing, due to their promising applications in both chemical and biological processes to produce alcohols, acids, oils, hydrocarbons, hydrogen, and other valuable products [1,15,22,34,46,47,[49][50][51][52][53][54][55]. However, up to now, only a few works discussed the employment of acid solid catalysts for the conversion of Arundo donax L. to value-added products, performing the reaction in the presence of ionic liquids as solvents, which have some criticisms related to their high viscosity, toxicity and cost, which strongly limit the sustainability of this approach.…”

Biohydrogen Production From Biomass Sources: Metabolic Pathways and Economic Analysis

“…The dark fermentation method involves converting complex matter into simpler products through hydrolysis (Kucharska et al, 2019), for instance, complex carbohydrates into reducing sugars. These simple compounds then go through acidification instigated by enzymes.…”