Investigation of a robust pretreatment technique based on ultrasound-assisted, cost-effective ionic liquid for enhancing saccharification and bioethanol production from wheat straw.

Application of cost-effective pretreatment of wheat straw is an important stage for massive bioethanol production. A new approach is aimed to enhance the pretreatment of wheat straw by using low-cost ionic liquid [TEA][HSO4] coupled with ultrasound irradiation. The pretreatment was conducted both at room temperature and at 130 °C with a high biomass loading rate of 20% and 20% wt water assisted by ultrasound at 100 W-24 kHz for 15 and 30 min. Wheat straw pretreated at 130 °C for 15 and 30 min had high delignification rates of 67.8% and 74.9%, respectively, and hemicellulose removal rates of 47.0% and 52.2%. Moreover, this pretreatment resulted in producing total reducing sugars of 24.5 and 32.1 mg/mL in enzymatic saccharification, respectively, which corresponds to saccharification yields of 67.7% and 79.8% with commercial cellulase enzyme CelluMax for 72 h. The ethanol generation rates of 38.9 and 42.0 g/L were attained for pretreated samples for 15 and 30 min, equivalent to the yields of 76.1% and 82.2% of the maximum theoretical yield following 48 h of fermentation. This demonstration provided a cheap and promising pretreatment technology in terms of efficiency and shortening the pretreatment time based on applying low-cost ionic liquid and efficient ultrasound pretreatment techniques, which facilitated the feasibility of this approach and could further develop the future of biorefinery.

Simultaneous Investigation of Three Effective Parameters of Substrate, Microorganism Type and Reactor Design on Power Generation in a Dual-Chamber Microbial Fuel Cells.

BACKGROUND: The use of Microbial Fuel Cells (MFCs) has been expanded in recent years due to their ability in producing bioelectricity and treating wastewater simultaneously. However, there are still some obstacles to use MFC on an industrial scale. Regardless of the restriction of electrodes applied in the electron transferring process, there are also some other factors having strong roles in reducing the power density of MFCs. OBJECTIVES: In this paper, the effect of three categories of limiting factors such as kinds of microorganisms (Saccharomyces cerevisiae and Shewanella sp.), substrate type (Glucose and acetate), and features reactor components have been investigated on the power density generation. Simultaneous investigation of these parameters and demonstration of which parameters would induce more power density can help to improve the scale­up of MFCs. MATERIALS AND METHODS: Two types of MFCs with different designs were constructed and inoculated with pure cultures of Saccharomyces cerevisiae PTCC 5269 and Shewanella sp. The OCV (Open Circuit Voltage) and polarization curves of MFCs were measured when the quasi­steady­state condition was observed. RESULTS: Based on results, utilizing acetate in the presence of both microorganisms led to approximately 60% higher power density compared to glucose. The comparison of maximum power densities of different reactor designs indicated an approximately 17-70 % increase of power generation. However, the resultant shows modification of reactor design even when other parameters are not optimal can increase power density more than three times. CONCLUSION: Actually, reactor design has the most important role in the power density with the MFC while the effects of substrate and microorganism parameters are not inappreciable.

Energy performance evaluation of ultrasonic pretreatment of organic solid waste in a pilot-scale digester.

It has been proven that ultrasonic pretreatment (UP) has positive effect on biogas generation from previous lab-scale studies. However, that is not always the case in larger scale processes. The purpose of this study was to evaluate the effectiveness of UP to biogas generation in terms of anaerobic digestion process and energy efficiency. Parameters including total solids (TS) and ultrasonic treatment operational parameters of organic solid waste (OSW) resulted from our past lab scale UP studies were applied in this study. OSW with 6-10% TS was treated using a lab-scale ultrasonic processor using various power densities (0.2-0.6 W/mL) at different time periods up to 30 min. Results of lab scale confirmed that OSW with 6% TS sonicated with 0.2 W/mL power density in 30 min gave the best outcome for the pilot scale experiment. To simulate the condition of an actual scale, in addition to energy analysis, two different organic loading rates (OLR), namely 500 and 1500 gVS/m3day were examined. The pilot digester was fed with OSW with or without the pretreatment based on the aforementioned specifications. The results showed that UP effectively improves biogas generation in terms of quantity and quality (CH4/CO2). Furthermore, it decreases the time to reach the maximum cumulative biogas volume comparing to the untreated feed. The key achievement of this research has confirmed that although the relative increase in the energy gain by the influence of UP was more remarkable under the 500 gVS/m3day OLR, energy analysis showed a better energy gain and energy benefit as well as jumping in biogas yield up to 80% for UP treated OSW under 1500 gVS/m3day OLR.

Introducing an attractive method for total biomimetic creation of a synthetic biodegradable bioactive bone scaffold based on statistical experimental design.

A new total biomimetic technique based on both the water uptake and degradation processes is introduced in this study to provide an interesting procedure to fabricate a bioactive and biodegradable synthetic scaffold, which has a good mechanical and structural properties. The optimization of effective parameters to scaffold fabrication was done by response surface methodology/central composite design (CCD). With this method, a synthetic scaffold was fabricated which has a uniform and open-interconnected porous structure with the largest pore size of 100-200µm. The obtained compressive ultimate strength of ~35MPa and compression modulus of 58MPa are similar to some of the trabecular bone. The pore morphology, size, and distribution of the scaffold were characterized using a scanning electron microscope and mercury porosimeter. Fourier transform infrared spectroscopy, EDAX and X-ray diffraction analyses were used to determine the chemical composition, Ca/P element ratio of mineralized microparticles, and the crystal structure of the scaffolds, respectively. The optimum biodegradable synthetic scaffold based on its raw materials of polypropylene fumarate, hydroxyethyl methacrylate and nano bioactive glass (PPF/HEMA/nanoBG) as 70/30wt/wt%, 20wt%, and 1.5wt/wt% (PHB.732/1.5) with desired porosity, pore size, and geometry were created by 4weeks immersion in SBF. This scaffold showed considerable biocompatibility in the ranging from 86 to 101% for the indirect and direct contact tests and good osteoblast cell attachment when studied with the bone-like cells.

Nickel oxide/carbon nanotube/polyaniline nanocomposite as bifunctional anode catalyst for high-performance Shewanella-based dual-chamber microbial fuel cell.

A novel nickel oxide/carbon nanotube/polyaniline (NCP) nanocomposite has been prepared and used to modify the electrocatalytic properties of carbon cloth anode in fabricating dual-chamber MFC. The prepared nanocomposite was characterized by scanning electron microscopy, X-ray diffraction, and fourier transform infrared spectroscopy. The carbon cloth coated with the NCP nanocomposite showed the enhanced electrochemical performance as compared to bare carbon cloth anode. The electrochemical properties of the fabricated MFC with the modified anode have been investigated by linear sweep voltammetry and electrochemical impedance spectroscopy. The maximum power density of the MFC using the novel NCP nanocomposite-carbon cloth anode increased by 61.88% compared to that of the bare carbon cloth anode. In comparison to the bare carbon cloth anode, the new composite anode showed 26.8% enhancement of current density output which it can be due to the enhancement of the charge transfer capability.

Variable optimization for biopulping of agricultural residues by Ceriporiopsis subvermispora.

Ceriporiopsis subvermispora was used for biochemical pulping of agricultural residues and the results were compared with chemical pulping. Independent variables were screened by Plackett-Burman and optimized by full factorial experimental designs. Biological treatment of rice, wheat and barley straw samples resulted in decrease of the kappa number of these straws by 34%, 21% and 19%, respectively, as compared with controlled samples. The tensile strength and burst factor of hand sheets produced from rice straw were increased by 51% and 33% as compared with the control straws. The tensile strength and burst factor of hand sheets produced from wheat straws were improved by 67% and 36%, these variables for barely straws were 36.7% and 45%, respectively. Although the delignification of wheat and barley straws are not as efficient as chemical process, but the quality of papers produced by biochemical pulping of straws were excellent.