Abstract
In this study the effect of nitrogen (N) supplementation in the fungal pretreatment of willow sawdust (WSD) via the white rot fungus Abortiporus biennis (A. biennis) was studied in terms of the fractionation of lignocellulosic biomass and biochemical methane potential (BMP). Thus, different external nitrogen sources (yeast extract (YE), urea (UR), and ammonium nitrate (AN)) at different ratios (N/C of 1/250 and 1/50) were added and the effect of the above parameters on the chemical composition of WSD during solid-state fermentation (SSF) experiments with A. biennis was assessed and compared to the experiment of fungal pretreatment without N supplementation (N/C was 1/500, control experiment). The results indicated that the addition of an external nitrogen source did not facilitate delignification, regardless of the type of nitrogen source and the ratio of N/C used. On the other hand, enhanced cellulose uptake was observed. Samples of the 28th day of cultivation, with and without N supplementation, were used for BMP tests, where a reduction in methane yield was observed, compared to the control experiment. In addition, a combination of fungal with alkali (20% NaOH w/w dry mass) pretreatment was performed in order to assess the effect of combined pretreatment on the lignocellulosic content and the BMP.
Highlights
Biofuel production has become an imperative need for future energy use due to the rapid depletion of the fossil fuels, and climate change, such as global warming and environmental pollution
The combination of two different pretreatment steps led to a 116.61% increase of biochemical methane potential (BMP) compared to the raw willow sawdust (WSD)
A combination of fungal with alkali pretreatment led to high lignin and holocellulose degradation, which was mainly due to the alkali pretreatment
Summary
Biofuel production has become an imperative need for future energy use due to the rapid depletion of the fossil fuels, and climate change, such as global warming and environmental pollution. Anaerobic digestion (AD) of lignocellulosic residues towards biogas production seems to be the most promising process for biofuels generation [1]. Its advantage compared to other biofuels is that methane gas could be used directly for heat and electricity. Lignocellulosic biomass is renewable, widely available, rich in complex carbohydrates (55%–75% in total solids (TS)), and not competitive with food or feed crops [2]. The biotransformation to methane is not an easy task, due to the complex structure of lignocellulose (cellulose is embedded in an amorphous matrix of hemicellulose and lignin) and the low biodegradability of lignin under anaerobic conditions [2]. A variety of physical, chemical, and biological pretreatment methods have been proposed so far, in order to break down the lignin seal and to enhance AD efficiency and biogas production [3]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
