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Biorefinery, an example of a multiple products system, integrates biomass conversion processes and equipment to produce fuels, power and chemicals from biomass. This study focuses on technical design, economic and environmental analysis of a lignocellulosic feedstock (LCF) biorefinery producing ethanol, succinic acid, acetic acid and electricity. As the potential worldwide demand of succinic acid and its derivatives can reach 30 million tons per year, succinic acid is a promising high-value product if production cost and market price are substantially lowered. The results of the economic analysis show that the designed refinery has great potentials compared to the single-output ethanol plant; even when the price of succinic acid is lowered or the capital investment doubled. In terms of eco-efficiency, the LCF biorefinery shows better environmental performances mainly in global warming potential due to CO(2) fixation during acid fermentation. The overall evaluation of the eco-efficiency depends on the importance attached to each impact category.

α-Galactosidases are important industrial enzymes for hemicellulosic biomass degradation or modification. In this study, six novel extracellular α-galactosidases from Penicillium subrubescens were produced in Pichia pastoris and characterized. All α-galactosidases exhibited high affinity to pNPαGal, and only AglE was not active towards galacto-oligomers. Especially AglB and AglD released high amounts of galactose from guar gum, carob galactomannan and locust bean, but combining α-galactosidases with an endomannanase dramatically improved galactose release. Structural comparisons to other α-galactosidases and homology modelling showed high sequence similarities, albeit significant differences in mechanisms of productive binding, including discrimination between various galactosides. To our knowledge, this is the first study of such an extensive repertoire of extracellular fungal α-galactosidases, to demonstrate their potential for degradation of galactomannan-rich biomass. These findings contribute to understanding the differences within glycoside hydrolase families, to facilitate the development of new strategies to generate tailor-made enzymes for new industrial bioprocesses.

The removal of antibiotics from wastewater has attracted much attention. In this research, an intimately coupled autarkical electrosorption (ES)-microbial fuel cell (MFC) system was developed for real-time removal of the antibiotic oxytetracycline (OTC) from wastewater. The removal efficiency was founded to be up to 98.8% at an OTC concentration of 2 mg/L with 3 g/L sodium acetate (NaAC) as co-substrate and 3 MFCs as power supply. The removal efficiencies increased in the ES unit and decreased in the MFC unit with increasing treating time. The adsorption of OTC on activated carbon fibers (ACFs) in the ES unit proceeds via chemical adsorption resulting from electrostatic attraction and cation exchange. The OTC degradation pathways in the MFC unit were proposed by identifying the intermediates with HPLC-MS/MS. The ACFs in the ES unit were proven to be recyclable and the coupled ES-MFC system is applicable for the removal of antibiotics from wastewater.

Anammox in the water line of a waste water treatment plant (WWTP) saves energy for aeration and allows for recovering biogas from organic material. Main challenges for applying the anammox process in the water line are related to the low temperature of <20°C, causing a significant drop in the specific anammox activity. The aim of this research was to enrich a cold-adapted anammox species, with a high specific activity. This was achieved in a 4.2L reactor operated at 10°C, fed with 61 mg (NH4+NO2)-N/L and inoculated with activated sludge from two selected municipal WWTPs. Candidatus Brocadia fulgida was the dominant species in the enriched biomass, with a specific activity was 30-44 mg N/(g VS d). This is two times higher than previously reported at 10°C, which is beneficial for full scale application. Biomass yield was 0.046 g biomass/g N converted, similar to that at higher temperatures.

Pervaporation can be applied in ethanol production from lignocellulosic biomass. Hydrophobic pervaporation, using a commercial PDMS membrane, was employed to concentrate the ethanol produced by fermentation of lignocellulosic hydrolysate. To our knowledge, this is the first report describing this. Pervaporation carried out with three different lignocellulosic fermentation broths reduced the membrane performance by 17-20% as compared to a base case containing only 3 wt.% ethanol in water. The membrane fouling caused by these fermentation broths was irreversible. Solutions containing model lignocellulosic components were tested during pervaporation at the same conditions. A total flux decrease of 12-15%, as compared to the base case, was observed for each component except for furfural. Catechol was found to be most fouling component whereas furfural permeated through the membrane and increased the total flux. The membrane selectivity increased in the presence of fermentation broth but remained unchanged for all selected components.

Xylitol is widely used in the food and pharmaceutical industries as a valuable commodity product. Biotechnological production of xylitol from lignocellulosic biomass by microorganisms is a promising alternative option to chemical synthesis or bioconversion from D-xylose. In this study, four metabolic mutants of Aspergillus niger were constructed and evaluated for xylitol accumulation from D-xylose and lignocellulosic biomass. All mutants had strongly increased xylitol production from pure D-xylose, beechwood xylan, wheat bran and cotton seed hulls compared to the reference strain, but not from several other feed stocks. The triple mutant ΔladAΔxdhAΔsdhA showed the best performance in xylitol production from wheat bran and cotton seed hulls. This study demonstrated the large potential of A. niger for xylitol production directly from lignocellulosic biomass by metabolic engineering.

Traditional pulp convective drying (CD) is time-consuming and energy-intensive. This study aimed to assess the drying performance of pulp using ultrasound-assisted drying (UAD) and compared it with CD to intensify moisture separation. UAD was found to be fast and efficient with high effective moisture diffusivity of 2.77 × 10-10 ∼ 3.20 × 10-10 m2/s, low activation energy of 20.2 kJ/mol, and short drying time of 21.0 ∼ 16.5 min. It demonstrated that applying ultrasound could promote moisture separation with 26 %∼42 % reductions in drying time and 42 %∼22 % savings in energy consumption. The constant rate period was not presented and no significant differences in drying rates were observed when the moisture ratio was below 0.43 under the investigated conditions. The kinetics modeling results indicated that the Page model was the best to predict the pulp drying kinetics for both methods. It may lead to an alternative efficient approach for decarbonizing the drying process in pulp and paper production.