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Bioenergy is considered a sustainable substitute to fossil-fuel resources and the development of a prudent combination of renewable and innovative conversion technologies are essential for the valorization and effective conversion of biowaste to value-added commodities. Here, a negative pressure-induced carbonization process was proposed for the valorization of lignin-enriched biowaste precursor to bio-oil and environmental materials (biochar) at various temperatures. The high heating values (HHV) of the as-prepared biochars from the lignin enriched precursor under negative pressure (low-medium vacuum) were within 25.9-31.5 MJ/kg, which matched satisfactorily to the commercial charcoal. Whereas, the bio-oils produced from the lignin enriched precursor under vacuum conditions was a blend of complex aromatic and straight-chain hydro-carbons, including aldehyde, ketone, phenol, and furans, exhibiting ability as potential heating-oil with HHV within 21.2-28.2 MJ/kg. Moreover, the biochars produced under vacuum environments at higher temperature showed greater stability (22.5-35.9%) than those produced under N2 atmosphere.

A vacuum fixed bed reactor was applied to pyrolyze lignite, biomass (rice husk) and their blend with high temperature (900 °C) and low heating rate (10 °C/min). Pyrolytic products were kept in the vacuum reactor during the whole pyrolysis process, guaranteeing a long contact time (more than 2 h) for their interactions. Remarkable synergetic effects were observed. Addition of biomass obviously influenced the tar and char yields, gas volume yield, gas composition, char structure and tar composition during co-pyrolysis. It was highly possible that char gasification, gaseous phase interactions, and secondary tar cracking were facilitated when lignite and biomass were co-pyrolyzed.

Implementing a circular economy aimed at reusing resources is becoming increasingly important for industry. Microalgae fit within a circular economy by being able to bioremediate nutrient waste and as a source of biomass for several commercial applications. Here, we report a novel validation of a circular economy concept using microalgae at a relevant industrial scale with a new two-phase process. During the first phase biomass was grown autotrophically, biomass was then concentrated using membrane technology for the second phase where mixotrophic conditions were applied to boost growth further. Microalgae cultures were able to grow (13.8 g/L), uptake and bioremediate nutrients (Nitrogen > 134 mg/L/day) from an anaerobic digestion side-stream (digestate), obtaining high quality microalgae biomass (>45% protein content) suitable for use as animal feed, closing the circular economy loop for industrial applications.

Influence of different pretreated sludge for electricity generation in microbial fuel cells (MFCs) was investigated in this study. Pre-treatment has shown significant improvement in MFC electricity productivity especially from microwave treated sludge. Higher COD reduction in the MFC has been revealed from microwave treated sludge with 55% for total and 85% for soluble COD, respectively. Nonetheless, longer ozonation treatment did not give additional advantage compared to the raw sludge. On the other hand, samples from anodes were analyzed using the 16S rRNA gene-based pyrosequencing technique for microbial community analysis. There was substantial difference in community compositions among MFCs fed with different pretreated sludge. Bacteroidetes was the abundant bacterial phylum dominated in anodes of higher productivity MFCs. These results demonstrate that using waste sludge as the substrate in MFCs could achieve both sludge reduction and electricity generation, and proper pre-treatment of sludge could improve the overall process performance.

Due to rapid deactivation of catalysts, the effective conversion of biomass with oxygen-rich and hydrogen-deficient characteristics to transportation fuels and high-valued chemicals via catalytic pyrolysis remains a challenge for commercialization. Hydrogen-rich plastic is used as feedstock co-fed with biomass to improve the catalytic pyrolysis process. The present work aims to investigate the co-pyrolysis process of cellulose and polyethylene (PE) over MgO by TG combined with photoionization time-of-flight mass spectrometry (PI-TOF-MS), which features on-line detection of catalytic pyrolysis products in real time. The MgO catalyst could improve the pyrolysis of cellulose and enhance the CC bond breaking of PE, respectively. During catalytic co-pyrolysis, the yields from olefins and furan as well as its derivatives can be enhanced obviously. Further, the formation of additional aromatics can be observed due to the Diels-Alder reaction. This work shows TG coupled to PI-TOF-MS is a powerful setup to study and optimize catalytic co-pyrolysis process.

The Fe(III)/Fe(II) couple can play a significant role in the abiotic reduction of 2-nitrophenol (2-NP) at the cathode chamber of a microbial fuel cell (MFC). Experimental results demonstrate that Fe(II) addition to the cathode chamber contributes to a significant increase in the reaction rate of 2-NP removal and the power performance of MFC. Observed pseudo first-order rate constants and power densities are heavily dependent on the identity of the Fe(II)-complexing ligands. The Fe(II) complex coordinated with citrate results in the highest rate constant up to 0.12 h(-1) as compared to other organically complexed iron species including Fe(II)-EDTA, Fe(II)-acetate and Fe(II)-oxalate, and iron species uncomplexed with any organic ligands. In addition, the presence of Fe(II)-citrate species leads to a maximum volumetric power density of 1.0 W m(-3), which is the highest value among those obtained with other iron species for the similar MFC system.

The effect of γ-irradiation pretreatment was compared with other pretreatment methods including ionic liquids (ILs), 1% HCl, 1% H2SO4, acidic aqueous Ils (AA-ILs), on the bioconversion efficiency of microcrystalline cellulose (MCC) for bioethanol production. The efficiency of MCC pretreatment followed with simultaneous saccharification and fermentation (SSF) was firstly evaluated according to the variations of the irradiation-derived compounds and structure of MCC, as well as yeast growth curve and bioethanol yield. Results showed that the appropriate irradiation dose (891 kGy used in our work) could eliminate the negative effect of toxic irradiation-derived compounds on SSF for ethanol bioconversion with the yield value of 67%. Analyses of SEM, FT-IR, reducing sugar and bioethanol yield showed that the efficiency of pretreatment on MCC was ILs ≈ irradiation pretreatment > AA-ILs pretreatment > 1% HCl pretreatment > 1% H2SO4 pretreatment.

Investigations were launched under atmospheres of different N2/CO2 ratios for thermo-degradation of lignocellulosic biomass and its chlorinated derivative that typically contains 10 wt.% poly(vinyl chloride) (PVC) over thermogravimetric analysis. Two degradation stages were found where CO2 was inert in stage one but changed to be reactive in stage two. Lignocellulosics were less reactive than their chlorinated derivatives. Non-isothermal thermogravimetric data were used for evaluating kinetics using Ozawa-Flynn-Wall and Vyazovkin methods. The values of apparent activation energy in stage one were 200-250 kJ/mol with less variance but varied greatly in stage two for different scenarios concerning CO2 proportion and PVC presence. These values were used to determine the reaction mechanism of each stage by master-plots method. Most processes were kinetically characterized by diffusion and reaction order models. The results afford a theoretical groundwork for the resourceful utilization of lignocellulosics derived from municipal activities and the development of their thermochemical conversion systems.